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29-12-2009, 11:50 AM
Post: #1
six stroke engine
hey guys any one hv any information about the six stroke engines then please reply..........
30-12-2009, 06:00 PM
Post: #2
RE: six stroke engine
One of the most difficult challenges in engine technology today is the urgent
need to increase engine thermal efficiency. The four strokes employed are intake stroke, compression stroke, expansion stroke, and exhaust stroke. In addition to these four strokes,this invention adds a secondary process having two additional strokes for scavenging the combustion chamber with fresh air. This additional two stroke scavenging process employs a fresh air intake stroke and a fresh air exhaust stroke to expel remaining gases.

Working of the apparatus
The overall cycle of thi sengine comprises the four strokes of a normal four stroke internal combustion engine including an intake stroke, compression stroke, expansion stroke and exhaust stroke;in which output power is generated, and a second scavenging process having two strokes, which is performed after these four strokes.The new two strokes introduced does the following:
1)intake stroke which introduces only air into the combustion chamber
2)exhaust stroke in which the remaining burnt gas in the combustion chamber is scavenged which otherwise, during the subsequent compression stroke inhibits the propagation of flame through the charge mixture due to residual gases.
In this apparatus, the cam shaft of the IC Engine is provided with an additional lobe on each cam which is rotated at a rate of one-third that of the crankshaft so that one complete cycle of the first process and second process is performed on every three revolutions of the crankshaft.Thus we have the intake cam and th eexhaust cam. The intake stroke of the first process and intake air stroke of the second scavenging process is achieved by separate lobes of the intake cam.And the exhaust stroke of the first process and the exhaust air stroke of the scavenging process are performed by separate lobes of the exhaust cam. The intake charge is recieved through i carburetor . the carburetor has two tracts:
1) primary tract through which air/fuel mixture is supplied during the intake stroke,

2)secondary tract through which fresh air is supplied during the air intake stroke of the second process.The operation of this tract is done by a solenoid valve responsive to the rotation of the cam shaft which controls the operation of the secondary tract to supply fresh air to the combustion chamber. This is accomplished through the use of an air flow controlling piston which controls the amount of air flow through the secondary fresh air flow passage in response to the temperature of the engine. Temp of engine is constantly tracked by temperature sensing washer installed under the spark plug. Due to this control mechanism, as the temperature of the engine increases, the amount of air flow through the engine is increased to cool the combustion chamber.

full report with detailed drawings download:

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03-03-2010, 04:56 PM
Post: #3
RE: six stroke engine

.doc  Six Stroke Engine.doc (Size: 655.5 KB / Downloads: 2670)

.ppt  Six Stroke Engine.ppt (Size: 487.5 KB / Downloads: 3441)

ABSTRACT
The quest for an engine which having the same or more power with higher fuel efficiency than the existing ones has started before many years. As a result of all these researches a new engine concept is formed, which is a six stroke engine. Lot of research works are conducting on this topic nowadays and already six types of six stroke engines were discovered yet. Of these the resent developed three six stroke engines, i.e., Beare head, Bruce crowers and Velozetaâ„¢s are undergoing tremendous research works.
During every cycle in a typical four stroke engine, piston moves up and down twice in the chamber, resulting in four total strokes and one of which is the power stroke that provides the torque to move the vehicle. But in a six stroke engine there are six strokes and out of these there are two power strokes. The automotive industry may soon be revolutionized by a new six-stroke design which adds a second power stroke, resulting in much more efficiency with less amount of pollution.

Presented By:
Eldhose Paul

INTRODUCTION
The term six stroke engine describes two different approaches in the internal combustion engine, developed since the 1990s, to improve its efficiency and reduce emissions
In the first approach, the engine captures the waste heat from the four stroke Otto cycle or Diesel cycle and uses it to get an additional power and exhaust stroke of the piston in the same cylinder. Designs either use steam or air as the working fluid for the additional power stroke. As well as extracting power, the additional stroke cools the engine and removes the need for a cooling system making the engine lighter and giving 40% increased efficiency over the normal Otto or Diesel Cycle. The pistons in this six stroke engine go up and down six times for each injection of fuel. These six stroke engines have 2 power strokes: one by fuel, one by steam or air. The currently notable six stroke engine designs in this class are the Crower's six stroke engine, invented by Bruce Crower of the U.S.A; the Bajulaz engine by the Bajulaz S A company, of Switzerland; and the Velozetaâ„¢s Six-stroke engine built by the College of Engineering, at Trivandrum in India.
The second approach to the six stroke engine uses a second opposed piston in each cylinder which moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine and also it increases the compression ratio. The currently notable six stroke engine designs in this class include two designs developed independently: the Beare Head engine, invented by Australian farmer Malcolm Beare, and the German Charge pump, invented by Helmut Kottmann.
SYMBOLS USED
1. TFC :- Total fuel consumption in Kg/Hr
2. SFC :- Specific fuel consumption in Kg/Kwhr
3. BP :- Brake power in Kw
4. TDC :- Top dead center
5. BDC :- Bottom dead center
6. IVO :- Inlet valve opening
7. IVC :- Inlet valve closing
8. EVO :- Exhaust valve opening
9. EVC :- Exhaust valve closing
10. N :- Engine speed at final drive shaft to the wheel in rpm
11. P :- Load in Kg
12. T :- Time for 10 cc fuel consumption
HISTORY OF SIX STROKE ENGINES
As mentioned earlier there are two approaches to study about six stroke engines, i.e., first and second. There are four types of engine comes under the first category of six stroke engines and two types of engine come under the second category.
First Category:-
The engines coming under this category are
1. Griffin six stroke engine:-
Griffin engine was the first six stroke engine developed in the world. It is developed by the engineer Samuel Griffin in 1883. In 1886 Scottish steam locomotive makers found a future in Griffinâ„¢s engine and they licensed the Griffin patents also marketed the engine under the name ËœKilmarnockâ„¢. They used this engine mainly for electric power generation. Only two known examples of a Griffin six-stroke engines survive today. One is in the Anson engine museum. The other was built in 1885 and for some years was in the Birmingham Museum of Science and Technology, but in 2007 it returned to Bath and the Museum of Bath at Work
2. Bajulaz six stroke engine:-
The Bajulaz Six Stroke Engine was invented in 1989 by the Bajulaz S A company, based in Geneva, Switzerland. The Bajulaz six stroke engine is similar to a regular combustion engine in design. There was however modifications to the cylinder head, with two supplementary fixed capacity chambers, a combustion chamber and an air preheating chamber above each cylinder. The combustion chamber receives a charge of heated air from the cylinder; the injection of fuel begins, at the same time it burns which increases the thermal efficiency compared to a burn in the cylinder. The high pressure achieved is then released into the cylinder to work the power or expansion stroke. Meanwhile a second chamber which blankets the combustion chamber has its air content heated to a high degree by heat passing through the cylinder wall. This heated and pressurized air is then used to power an additional stroke of the piston.
The advantages of the engine include reduction in fuel consumption by 40%, multi-fuel usage capability, and a dramatic reduction in pollution
3. Crower six stroke engine:-
This engine is invented by Bruce crower of California in USA in the year 2004. Bruce Crower is actually a race car mechanic with his own workshop. In his six-stroke engine, power is obtained in the third and sixth strokes. First four strokes of this engine are similar to a normal four stroke engine and power is delivered in the third stroke. Just prior to the fifth stroke, water is injected directly into the heated cylinder via the converted diesel engine's fuel injector pump. The injected water absorbs the heat produced in the cylinder and converts into superheated steam, which causes the water to expand to 1600 times its volume and forces the piston down for an additional stroke i.e. the second power stroke. The phase change from liquid to steam removes the excess heat of the engine.
As a substantial portion of engine heat now leaves the cylinder in the form of steam, no cooling system radiator is required. Energy that is dissipated in conventional arrangements by the radiation cooling system has been converted into additional power strokes. In Crower's prototype, the water for the steam cycle is consumed at a rate approximately equal to that of the fuel, but in production models, the steam will be recaptured in a condenser for re-use.
Second category:-
The engines coming under this category are
1. Beare Head six stroke engine:-
Malcolm Beare 47 year old Australian wheat farmer is the inventor of this six stroke engine. Actually the name six stroke engines was introduced by Malcolm Beare. Beare created an innovative hybrid engine, combining two-strokes in the top end with a four-stroke above the middle portion. So by adding this four plus two equals six, he derived the name six stroke engines.
Below the cylinder head gasket, everything is conventional, in his design. So one main advantage is that the Beare concept can be transplanted to existing engines without any redesigning or retooling the bottom end and cylinder. But the cylinder head and its poppet valves get thrown away in this design. To replace the camshaft and valves, Beare used a short-stroke upper crankshaft complete with piston, which is driven at half engine speed through the chain drive from the engine. This piston moves against the main piston in the cylinder and if the bottom piston comes four times upwards, upper piston will come downwards twice. The compression of charge takes place in between these two pistons. Much higher compression ratios can be obtained in this engine. Malcolm used on his first six-stroke, based on a Honda XL125 farm bike. Malcolm Beare claims his engine is 35% more economical at low revs/throttle openings than an equivalent conventional engine and 13% less thirsty at high rpm/full throttle.
2. Charge pump engine:-
In this engine, similar in design to the Beare head, a Ëœpiston chargerâ„¢ replaces the valve system. The piston charger charges the main cylinder and simultaneously regulates the inlet and the outlet aperture leading to no loss of air and fuel in the exhaust. In the main cylinder, combustion takes place every turn as in a two-stroke engine and lubrication as in a four-stroke engine. Fuel injection can take place in the piston charger, in the gas transfer channel or in the combustion chamber. It is also possible to charge two working cylinders with one piston charger. The combination of compact design for the combustion chamber together with no loss of air and fuel is claimed to give the engine more torque, more power and better fuel consumption. The benefit of less moving parts and design is claimed to lead to lower manufacturing costs. Good for hybrid technology and stationary engines. The engine is claimed to be suited to alternative fuels since there is no corrosion or deposits left on valves. The six strokes are: aspiration, pre-compression, gas transfer, compression, ignition and ejection.
VELOZETAâ„¢S SIX STROKE ENGINE
Mechanical Engineering students of the college of Engineering in Trivandrum, in the year 2006 made this six stroke engine as a part of their B.Tech project. After the completion of the course they formed the company Velozeta with the help of state and central government. They have got the patent of this engine also.
In Velozetaâ„¢s six stroke engine, a four-stroke Honda engine was experimentally altered to build the six stroke engine.The first four strokes of this engine are just like a conventional four stroke engine. The additional two strokes are for better scavenging and cooling of the engine which is provided by a secondary air induction system.
Theory:-
There is only a slight difference between Crowerâ„¢s six stroke engine and Velozetaâ„¢s six stroke engine. In the Crowerâ„¢s six stroke engine and this engine, the first four stokes are the same as a conventional four stroke engine. In Crowers engine during the fifth stroke water is injected into the cylinder and converted to steam which is used for expansion and the sixth stroke eliminates the expanded vapors through the exhaust manifold. But here the difference is that in the fifth stroke, instead of water, air from an air filter is sucked into the cylinder through a secondary air line provided at the exhaust manifold. In the sixth stroke, a mixture of this air and unburned gases are pushed out through the exhaust valve.
Engine parts modified:-
1) Camshaft / Crankshaft Sprockets
In the six stroke engine the crankshaft has 1080 degrees of rotation for 360 degree rotation of the camshaft per cycle. Hence their corresponding sprockets are having teeth in the ratio 3:1.In the original four stroke engine the teeth of the sprockets of the crankshaft and the camshaft were in 2:1 ratio. The 34 teeth sprocket of the four stroke engine camshaft was replaced by a 42 teeth sprocket in the six stroke engine. The camshaft sprockets were also replaced from 17 teeth to 14 teeth to convert the four stroke engine into six stroke engine.
2) Cam lobes
In the six stroke engine the 360 degrees of the cam has been divided into 60 degrees among the six strokes. The valve provided at the exhaust has to be kept open during the fourth, fifth and the sixth stroke. The cam has been made double lobed in order to avoid the hitting of the exhaust valve with the piston head. The profiles of the exhaust and the inlet cams have been shown in the figure 1.
Figure 1: cam lobes
3) Valve Timing
The valve timing of the four stroke Honda engine has been changed. The inlet valve opening (IVO) is 0° at TDC, same as that of the four stroke Honda activa engine. Inlet valve Closes (IVC) at 25° after BDC, same as that of the four stroke engine. Exhaust valve opens (EVO) 0° at BDC, which in the original engine was 25° before BDC. Velozeta reduced this 25° advanced opening of exhaust valve to extract maximum work per cycle. Exhaust valve closes 10 degree before TDC in order to prevent the loss of air fuel mixture through the exhaust valve. Two reed valves have been provided for the proper working of the engine.
4) Secondary Air Induction System
The secondary air induction system, supplies the air which is used during the fifth and sixth stroke. During the fifth stroke air from the air filter (fig24) is sucked into the cylinder through the secondary air induction line. The reed valve (fig22) opens to permit the air flow. During the sixth stroke, the air is removed through the exhaust manifold (fig 13). The reed valve (fig 23) opens and the reed valve (fig 22) closes during this stroke. The inlet valve remains closed during these strokes.
Working of velozeta six stroke engine:-
The detailed working of the six stroke engine has been explained by using figures 2-7, which give explanations regarding the each stroke. A detailed label of the engine parts has been given in page (4). The working of the engine is as follows. Also the detailed label of engine parts in the figures is given allow.
Detailed Label of Engine Parts:-
1. Rings
2. Inlet Manifold
3. Cylinder Head
4. Cam shaft
5. Cam Lob No.1
6. Inlet valve
7. Sprocket 42T
8. Rocker Arm
8.1. Inlet Rocker arm
8.2. Exhaust Rocker arm
9. Head Cover
10. Cam Lob no.3
11. Exhaust valve
12. Cam Lob No.2
13. Exhaust Manifold
14. Spark plug
15. Cylinder
16. Piston
17. Connecting rod
18. Timing Chain
19. Sprocket 14T
20. Crank
21. Secondary air induction unit
22. Reed valve (One way valve)
23. Reed valve (One way valve in Exhaust manifold)
24. Air filter
25. 42T sprocket holder
26. Bearing
First stroke (Figure 2):-
During the first stroke the inlet valve (6) opens and air-fuel mixture from carburetor is sucked into the cylinder through the inlet manifold (2).
Figure 2: First Stroke
Second stroke (Figure 3):-
During the second stroke, piston moves from BDC to TDC, both the inlet valve (6) and exhaust valve (11) are closed and the air-fuel mixture is compressed. The compression ratio of the modified engine is same as that of the original four stroke Honda engine 9:1.
Figure 3: Second Stroke
Third stroke (Figure 4):-
During the third stroke, power is obtained from the engine by igniting the compressed air- fuel mixture using a spark plug (14). Both valves remain closed. Piston moves from TDC to BDC.
Figure4: Third Stroke
Fourth stroke (Figure 5):-
During the fourth stroke, the exhaust valve (11) and the reed valve (23) opens to remove the burned gases from the engine cylinder. Piston moves from BDC to TDC.
Figure 5: Fourth Stroke
Fifth stroke (Figure 6):-
During the fifth stroke, the exhaust valve (11) remains open and the reed valve (23) closes. Fresh air from the air filter (24) enters the cylinder through the secondary air induction line (21) provided at the exhaust manifold (13). The reed valve (22) opens.
Figure 6: Fifth Stroke
Sixth stroke (Figure 7):-
During the sixth stroke, the exhaust valve (11) remains open. The air sucked into the cylinder during the fifth stroke is removed to the atmosphere through the exhaust manifold (13). The reed valve (23) opens and the reed valve (22) closes.
Figure 7: Sixth Stroke
Performance test results:-
Two tests i.e., Engine load test and Pollution, test was conducted on the six stroke engine and on the same four stroke engine from which the six stroke was developed.
Experimental Procedure:-
The same engine was altered as four stroke and six stroke to perform the experiments. Load test and pollution test were conducted. The load test was conducted using brake drum dynamometer. The final drive shaft from the engine to the wheel was used for loading during the experiment. The engines were tested for 320rpm and640rpm under the same loading conditions. The time for consumption of 10cc of the fuel was noted during the experiment. The % vol. of CO in exhaust gas during idling was tested to check the pollution level of the engines. The results of load test and pollution test have been tabulated in table (1) and table (2) respectively.
Load test results:-

Table 1: Load Test
Pollution Test Results:-
Graphs:-
Graph-1: Bp Vs TFC & SFC at 320rpm
Graph-2: Bp Vs TFC & SFC at 640 rpm
Advantages of the Engine
Reduction in fuel consumption
Dramatic reduction in pollution normally up to 65%
Better scavenging and more extraction of work per cycle
Lower engine temperature - so , easy to maintain the optimum engine temperature level for better performance
Less friction “ so , less wear and tear
The six-stroke engine does not require any basic modification to the existing engines. All technological experience and production methods remain unaltered
Higher overall efficiency
CONCLUSION
The six stroke engine modification promises dramatic reduction of pollution and fuel consumption of an internal combustion engine. The fuel efficiency of the engine can be increased and also the valve timing can be effectively arranged to extract more work per cycle. Better scavenging is possible as air intake occurs during the fifth stroke and the exhaust during the sixth stroke. Due to more air intake, the cooling system is improved. It enables lower engine temperature and therefore increases in the overall efficiency.
REFERANCES
¢ http://www.autoweekapps/pbcs.dll/article...WEEKSISSUE
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Article%20The%20Beare%206%20Stroke%20Ducati%20-%20Alan%20Cathcart.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Beare%20Technology%20-%20Innovative%20Engine%20Design.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Construction%20of%20SixStroke%20Internal%20Combustion%20Motors.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Motorcycle%20engineering%20-%20sixstroke%20engine.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Motorcycle%20Pictures%20-%20The%20Beare%20Ducati%20Images.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Theory%20of%20Six%20Stroke%20Internal%20Combustion%20Enginewe.htm
¢ file:///H:/abc/BEARE-Six%20Stroke%20Engine/Theory%20of%20Six%20Stroke%20Internal%20Combustion%20Engine.htm
¢ http://www.velozeta
¢ http://www.newindpressNewsItems.aspID=IEO20060903112344&Topic=0&Title=Thiruvananthapuram&Page=O
¢ http://www.autocarindianew/Information.aspid=1263
¢ http://en.wikipediawiki/Six_stroke_engine
¢ http://en.wikipediawiki/Crower_six_stroke
15-03-2010, 10:43 PM
Post: #4
RE: six stroke engine
The six-stroke engine is a type of internal combustion engine based on the four-stroke engine, but with additional complexity to make it more efficient and reduce emissions. Two different types of six-stroke engine have been developed since the 1990s:

1. In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air. The currently notable designs in this class are the Crower six-stroke engine, invented by Bruce Crower of the U.S. ; the Bajulaz engine by the Bajulaz S.A. company of Switzerland; and the Velozeta Six-stroke engine built by the College of Engineering, at Trivandrum in India.
2. The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio. The currently notable designs in this class include two designs developed independently: the Beare Head engine, invented by Australian Malcolm Beare, and the German Charge pump, invented by Helmut KottmannGriffin six-stroke engine

In 1883, the Bath-based engineer Samuel Griffin was an established maker of steam and gas engines. He wished to produce an internal combustion engine, but without paying the licensing costs of the Otto patents. His solution was to develop a 'Patent slide valve' and a single-acting six-stroke engine using it.

By 1886, Scottish steam locomotive maker Dick, Kerr & Co. saw a future in large oil engines and licensed the Griffin patents. These were double acting, tandem engines and sold under the name "Kilmarnock". A major market for the Griffin engine was in electricity generation, where they developed a reputation for happily running light for long periods, then suddenly being able to take up a large demand for power. Their large heavy construction didn't suit them to mobile use, but they were capable of burning heavier and cheaper grades of oil.

The key principle of the "Griffin Simplex" was a heated exhaust-jacketed external vapouriser, into which the fuel was sprayed. The temperature was held around 550 °F (288 °C), sufficient to physically vapourise the oil but not to break it down chemically. This fractional distillation supported the use of heavy oil fuels, the unusable tars and asphalts separating out in the vapouriser.

Hot bulb ignition was used, which Griffin termed the 'Catathermic Igniter' , a small isolated cavity connected to the combustion chamber. The spray injector had an adjustable inner nozzle for the air supply, surrounded by an annular casing for the oil, both oil and air entering at 20 lbs sq in. pressure, and being regulated by a governor The Bajulaz six-stroke engine is similar to a regular combustion engine in design. There are however modifications to the cylinder head, with two supplementary fixed capacity chambers: a combustion chamber and an air preheating chamber above each cylinder. The combustion chamber receives a charge of heated air from the cylinder; the injection of fuel begins an isochoric burn which increases the thermal efficiency compared to a burn in the cylinder. The high pressure achieved is then released into the cylinder to work the power or expansion stroke. Meanwhile a second chamber which blankets the combustion chamber, has its air content heated to a high degree by heat passing through the cylinder wall. This heated and pressurized air is then used to power an additional stroke of the piston.

The advantages of the engine include reduction in fuel consumption by at least 40%, two expansion strokes in six strokes, multi-fuel usage capability, and a dramatic reduction in pollution
Velozeta six-stroke engine

In a Velozeta engine, during the exhaust stroke, fresh air is injected into the cylinder, which expands by heat and therefore forces the piston down for an additional stroke. The valve overlaps have been removed and the two additional strokes using air injection provide for better gas scavenging. The engine seems to show 40% reduction in fuel consumption and dramatic reduction in air pollution.[7] Its specific power is not much less than that of a four-stroke petrol engine.[7] The engine can run on a variety of fuels, ranging from petrol and diesel to LPG. An altered engine shows a 65% reduction in carbon monoxide pollution when compared with the four stroke engine from which it was developed.

The Velozeta engine features are:

* Reduction in fuel consumption
* Dramatic reduction in pollution
* Better scavenging and more extraction of work per cycle
* Lower working temperature makes it easy to maintain optimum engine temperature level for better performance
* The six-stroke engine does not require significant modification to existing engines.
* Better cooling due to additional air strokes, which mostly removes the need for a cooling system
* Lighter engine

Crower six stroke

In a six-stroke engine developed in the U.S. by Bruce Crower, fresh water is injected into the cylinder after the exhaust stroke, and is quickly turned to superheated steam, which causes the water to expand to 1600 times its volume and forces the piston down for an additional stroke. This design also claims to reduce fuel consumption by 40%. Maximum efficiency would theoretically be obtained by applying the design to a non-turbocharged diesel engine, where the high compression ratio would allow greater expansion of the steam.

The Crower six-stroke engine was invented in 2004 by 75 year old American inventor Bruce Crower who has applied for a patent on a design involving fresh water injection into the cylinders. As of May 2008, no patent has been awarded. Leonard Dyer invented the first six-stroke internal combustion water injection engine in 1915, which is very similar to Crower's design. [11] Crower's six-stroke engine features:

* No cooling system required
* Improves a typical engineâ„¢s fuel consumption
* Requires a supply of distilled water to act as the medium for the second power stroke.

Beare Head

The term "Six Stroke" was coined by the inventor of the Beare Head, Malcolm Beare. The technology combines a four stroke engine bottom end with an opposed piston in the cylinder head working at half the cyclical rate of the bottom piston. Functionally, the second piston replaces the valve mechanism of a conventional engine.
Piston charger engine

In this engine, similar in design to the Beare head, a "piston charger" replaces the valve system. The piston charger charges the main cylinder and simultaneously regulates the inlet and the outlet aperture leading to no loss of air and fuel in the exhaust.
In the main cylinder, combustion takes place every turn as in a two-stroke engine and lubrication as in a four-stroke engine. Fuel injection can take place in the piston charger, in the gas transfer channel or in the combustion chamber. It is also possible to charge two working cylinders with one piston charger. The combination of compact design for the combustion chamber together with no loss of air and fuel is claimed to give the engine more torque, more power and better fuel consumption. The benefit of less moving parts and design is claimed to lead to lower manufacturing costs. Good for hybrid technology and stationary engines. The engine is claimed to be suited to alternative fuels since there is no corrosion or deposits left on valves. The six strokes are: aspiration, precompression, gas transfer, compression, ignition and ejection. This is an invention of Helmut Kottmann from Germany, working 25 years at MAHLE GmbH piston and cylinder construction.

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09-05-2010, 01:24 AM
Post: #5
RE: six stroke engine

.pptx  6 STROKE DIESEL ENGINE (RAI).pptx (Size: 789.48 KB / Downloads: 797)

SIX STROKE DIESEL ENGINE


Presented By
PRASIDH. RAI. K
USN: 1JS06ME031
8th Semester
J.S.S. Academy of Technical Education
Department of Mechanical Engineering

INTRODUCTION

The six-stroke engine is a type of internal combustion engine based on the four-stroke engine.
First developed in early 1990â„¢s
Advancement is the Duel fuel six stroke diesel engine
More efficient & reduce emissions.



Approaches for six stroke engine design

First approach
There is two additional strokes by the main piston as fifth and sixth stroke
Second approach
It uses a second opposed piston which moves at half the cyclical rate of the main piston


BAJULAZ SIX STROKE ENGINE

1. Intake valve
2. Heating chamber valve
3. Combustion chamber valve
4. Exhaust valve
5. Cylinder
6. Combustion chamber
7. Air heating chamber
8. Wall of combustion chamber
9. Fuel injector
10. Heater plug


ADVANTAGES

Reduction in fuel consumption by at least 40%
Two expansions(work/Power stroke) in six strokes
Dramatic reduction in pollution ( up to 65%)
Higher overall efficiency
Lower engine temperature & noise level
Due to more air intake, the cooling system is improved
Better scavenging and more extraction of work per cycle
Less inertia due to lightness of moving parts



DISADVANTAGES

Brake power & indicated power per cycle per cylinder is comparatively lesser
Engine size increases due to many number of cylinders & additional components
Higher manufacturing cost of six stroke engine


APPLICATIONS

Automobiles, heavy goods, construction-site and farm vehicles.
motor-pumps, generator sets, stationary engines, etc....intended for agriculture and industry.
Motorboats



CONCLUSION

Drastically reducing fuel consumption (by 40%) and pollution (by 60-90%) without radically affecting performances
For the dual fuel six-stroke engine, soot & nitrous oxide was practically eliminated by a small amount of methanol in the second combustion process.
It enables lower engine temperature and therefore increases in the overall efficiency.

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18-05-2010, 02:33 PM
Post: #6
RE: six stroke engine

.doc  Six stroke engine.doc (Size: 892.5 KB / Downloads: 606)

1. INTRODUCTION

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression. Diesel engines have wide range of utilization for automobiles, locomotives & marines and co-generation systems. However, large problem is still related to undesirable emission.

The six-stroke engine is a type of internal combustion engine based on the four-stroke engine but with additional complexity to make it more efficient and reduce emissions. Two different types of six-stroke engine have been developed:

In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air. The currently notable designs in this class are the Crower Six-stroke engine invented by Bruce Crower of the U.S. ; the Bajulaz engine by the Bajulaz S.A. company of Switzerland; and the Velozeta Six-stroke engine built by the College of Engineering, at Trivandrum in India.

The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio. The currently notable designs in this class include two designs developed independently: the Beare Head engine, invented by Australian Malcolm Beare, and the German Charge pump, invented by Helmut Kottmann.

To improve exhaust emissions from diesel engines, a new concept of Six Stroke Engine has been proposed. This engine has a second com¬pression and combustion processes before exhaust pro¬cess.

Fig 1 Diesel engine sectional view Fig 2 Ideal Otto cycle



Fig 3 Pressure- Volume diagrams for dual cycle


As the fuel in one cycle was divided into two combus¬tion processes and the EGR (Exhaust Gas Recirculation) effect appeared in the sec¬ond combustion process, the decreased maximum cylinder temperature reduced Nitrous Oxide (NO) concentration in the exhaust gas. It was further confirmed that soot formed in the first combustion process was oxidized in the second combustion process .Therefore, a six¬ stroke diesel engine has significant possibilities to improve combustion process because of its more control¬lable factors relative to a conventional four-stroke engine.

Since the cylinder temperature before the second combustion process is high because of an increased temperature in the first combustion process, ignition delay in the second combustion process should be shortened. In addition, typically less desirable low cet¬ane number fuels might also be suitable for use in the second combustion process, because the long ignition delays of these fuels might be improved by increased cyl¬inder temperatures from the first combustion process.

Methanol was chosen as the fuel of the second combustion. The cetane number of methanol is low and it shows low ignitability. However, since methanol will form an oxidizing radical (OH) during combustion, it has the potential to reduce the soot produced in the first combustion process.




Fig 4 Comparison of 4 stroke and 6 stroke cycle





2. BAJULAZ SIX STROKE ENGINE

The majority of the actual internal combustion engines, operating on different cycles have one common feature, combustion occurring in the cylinder after each compression, resulting in gas expansion that acts directly on the piston (work) and limited to 180 degrees of crankshaft angle.

According to its mechanical design, the six-stroke engine with external and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: Combustion, does not occur within the cylinder within the cylinder but in the supplementary combustion chamber, does not act immediately on the piston, and itâ„¢s duration is independent from the 180 degrees of crankshaft rotation that occurs during the expansion of the combustion gases (work).

The combustion chamber is totally enclosed within the air-heating chamber. By heat exchange through the glowing combustion chamber walls, air pressure in the heating chamber increases and generate power for an a supplementary work stroke. Several advantages result from this, one very important being the increase in thermal efficiency. IN the contemporary internal combustion engine, the necessary cooling of the combustion chamber walls generates important calorific losses.

2.1 Analysis:

Six-stroke engine is mainly due to the radical hybridization of two- and four-stroke technology. The six-stroke engine is supplemented with two chambers, which allow parallel function and results a full eight-event cycle: two four-event-each cycles, an external combustion cycle and an internal combustion cycle. In the internal combustion there is direct contact between air and the working fluid, whereas there is no direct contact between air and the working fluid in the external combustion process. Those events that affect the motion of the crankshaft are called dynamic events and those, which do not effect are called static events.


Fig 5 Prototype of Six stroke engine internal view

1. Intake valve, 2.Heating chamber valve,
3.Combustion chamber valve, 4. Exhaust valve,
5.Cylinder, 6.Combustion chamber,
7. Air heating chamber, 8.Wall of combustion chamber,
9.Fuel injector and 10.Heater plug.




2.1.1 Analysis of events

Fig 6 Event 1: Pure air intake in the cylinder (dynamic event)

1. Intake valve.
2. Heating chamber valve
3. Combustion chamber valve.
4. Exhaust valve
5. Cylinder
6. Combustion chamber.
7. Air heating chamber.
8. Wall of combustion chamber.
9. Fuel injector.
10. Heater plug.



Fig 7 Event 2: Pure air compression in the heating chamber.

Event 3: Keeping pure air pressure in closed chamber where a maximum heat exchange occurs with the combustion chambers walls, without direct action on the crankshaft (static event).



Fig 8 Event 4: Expansion of the Super heat air in the cylinder work (dynamic Event).





Fig 9 Event 5: Re-compressions of pure heated air in the combustion chamber (dynamic event).


Events 6: fuel injection and combustion in closed combustion chamber, without direct action on the crankshaft (static event).


Fig 10 Events 7: Combustion gases expanding in the cylinder, work (dynamic event).


Fig 11 Events 8: Combustion gases exhaust (dynamic event).

Fig 12 Six-stroke engine cycle diagram:

2.1.2 External combustion cycle: (divided in 4 events):

No direct contact between the air and the heating source.

e1. (Event 1) Pure air intake in the cylinder (dynamic event).
e2. (Event 2) Compression of pure air in the heating chamber (dynamic event).
e3. (Event 3) Keeping pure air pressure in closed chamber where a maximum heat exchange occurs with the combustion chambers walls, without direct action on the crankshaft (static event).

e4. (Event 4) Expansion of the super heated air in the cylinder, work (dynamic event).

2.1.3 Internal combustion cycle: (divided in 4 events)

Direct contact between the air and the heating source.
I1. (Event 5) Re-compression of pure heated air in the combustion chamber (dynamic event)
I2. (Event 6) Fuel injection and combustion in closed combustion chamber, without direct action on the crankshaft (static event).
I3. (Event 7) Combustion gases expanding in the cylinder, work (dynamic event).
I4. (Event 8) Combustion gases exhaust (dynamic event).







2.2 Constructional details:

The sketches shows the cylinder head equipped with both chambers and four valves of which two are conventional (intake and exhaust). The two others are made of heavy-duty heat-resisting material. During the combustion and the air heating processes, the valves could open under the pressure within the chambers. To avoid this, a piston is installed on both valve shafts which compensate this pressure. Being a six-stroke cycle, the camshaft speed in one third of the crankshaft speed.

The combustion chambers walls are glowing when the engine is running. Their small thickness allows heat exchange with the air-heating chamber, which is surrounding the combustion chamber. The air-heating chamber is isolated from the cylinder head to reduce thermal loss.

Through heat transfer from the combustion chamber to the heating chamber, the work is distributed over two strokes, which results in less pressure on the piston and greater smoothness of operation. In addition, since the combustion chamber is isolated from the cylinder by its valves, the moving parts, especially the piston, are not subject to any excessive stress from the very high temperatures and pressures. They are also protected from explosive combustion or auto-ignition, which are observed on ignition of the air-fuel mixture in conventional gas or diesel engines.

The combustion and air-heating chambers have different compression ratio. The compression ratio is high for the heating chamber, which operates on an external cycle and is supplied solely with pure air. On the other hand, the compression ratio is low for the combustion chamber because of effectively increased volume, which operates on internal combustion cycle.

The combustion of all injected fuel is insured, first, by the supply of preheated pure air in the combustion chamber, then, by the glowing walls of the chamber, which acts as multiple spark plugs. In order to facilitate cold starts, the combustion chamber is fitted with a heater plug (glow plug). In contrast to a diesel engine, which requires a heavy construction, this multi-fuel engine, which can also use diesel fuel, may be built in a much lighter fashion than that of a gas engine, especially in the case of all moving parts.

Injection and combustion take place in the closed combustion chamber, therefore at a constant volume, over 360 degrees of crankshaft angle. This feature gives plenty of time for the fuel to burn ideally, and releases every potential calorie (first contribution to pollution reduction). The injection may be split up, with dual fuel using the SNDF system (Single Nozzle, Dual Fuel). The glowing walls of the combustion chamber will calcite the residues, which are deposited there during fuel combustion (second contribution to pollution reduction).

As well as regulating the intake and exhaust strokes, the valves of the heating and the combustion chambers allow significantly additional adjustments for improving efficiency and reducing noise.



2.3 Factors Contributing To the Increased Thermal Efficiency,
Reduced Fuel Consumption, and Pollutant Emission
1. The heat that is evacuated during the cooling of a conventional engineâ„¢s cylinder head is recovered in six-stroke engine by air-heating chamber surrounding the combustion chamber.
2. After intake, air is compressed in the heating chamber and heated through 720 degrees of crankshaft angle, 360 degrees of which in closed chamber (external combustion).
3. The transfer of heat from thin walls of the combustion chamber to the air heating chambers lowers the temperature, pressure of gases on expansion and exhaust (internal combustion).
4. Better combustion and expansion of gases that take place over 540 degrees of crankshaft rotation, 360° of which is in closed combustion chamber, and 180° for expansion.
5. Elimination of the exhaust gases crossing with fresh air on intake. In the six stroke-engines, intake takes place on the first stroke and exhaust on the fourth stroke.
6. Large reduction in cooling power. The water pump and fan outputs are reduced. Possibility to suppress the water cooler.
7. Less inertia due to the lightness of the moving parts.
8. Better filling of the cylinders on the intake due to the lower temperature of the cylinder walls and the piston head.
9. The glowing combustion chamber allows the finest burning of any fuel and calcinate the residues.
10. Distribution of the work: two expansions (power strokes) over six strokes, or a third more than the in a four-stroke engine.
Since the six-stroke engine has a third less intake and exhaust than a four stroke engine, the depression on the piston during intake and the back pressure during exhaust are reduced by a third. The gain in efficiency balances out the losses due to the passage of air through the combustion chamber and heating chamber valves, during compression of fresh and superheated air. Recovered in the six-stroke engine
By the air-heating chamber surrounding the combustion. Friction losses, theoretically higher in the six-stroke engine, are balanced by a better distribution of pressure on the moving parts due to the work being spread over two strokes and the elimination of the direct combustion.
3. DUAL FUEL SIX STROKE ENGINE

3.1 Working

The cycle of this engine consists of six strokes:
1. Intake stroke
2. First compression stroke
3. First combustion stroke
4. Second compression stroke
5. Second combustion stroke
6. Exhaust stroke


Fig 13 Concept of a Six-stroke diesel engine

3.1.1 Intake or Suction stroke

To start with the piston is at or very near to the T.D.C., the inlet valve is open and the exhaust valve is closed. A rotation is given to the crank by the energy from a flywheel or by a starter motor when the engine is just being started. As the piston moves from top to bottom dead centre the rarefaction is formed inside the cylinder i.e. the pressure in the cylinder is reduced to a value below atmospheric pressure. The pressure difference causes the fresh air to rush in and fill the space vacated by the piston. The admission of air continues until the inlet valve closes at B.D.C.

3.1.2 First Compression stroke

Both the valves are closed and the piston moves from bottom to top dead centre. The air is compressed up to compression ratio that depends upon type of engine. For diesel engines the compression ratio is 12-18 and pressure and temperature towards the end of compression are 35-40 kgf/cm2 and 600-700 0C

3.1.3 First combustion stroke

This stroke includes combustion of first fuel (most probably diesel) and expansion of product of combustion. The combustion of the charge commences when the piston approaches T.D.C.

Here the fuel in the form of fine spray is injected in the combustion space. The atomization of the fuel is accomplished by air supplied. The air entering the cylinder with fuel is so regulated that the pressure theoretically remains constant during burning process.

In airless injection process, the fuel in finely atomized form is injected in combustion chamber. When fuel vapors raises to self ignition temperature, the combustion of accumulated oil commences and there is sudden rise in pressure at approximately constant volume. The combustion of fresh fuel injected into the cylinder continues and this ignition is due to high temperature developed in engine cylinder. However this latter combustion occurs at approximately constant pressure.

Due to expansion of gases piston moves downwards. The reciprocating motion of piston is converted into rotary motion of crankshaft by connecting rod and crank. During expansion the pressure drop is due to increase in volume of gases and absorption of heat by cylinder walls.

3.1.4 Second compression stroke

Both the valves are closed and the piston moves from bottom to top dead centre. The combustion products from the first compression stroke are recompressed and utilized in the second combustion process before the exhaust stroke. In typical diesel engine combustion the combustion products still contains some oxygen.

3.1.5 Second combustion stroke

This stroke includes combustion of second fuel having low cetane (Cetane number of fuel is defined as percent volume of cetane (C16H34) in a mixture of cetane and alpha-methyl-naphthalene that produces the same delay period or ignition lag as the fuel being tested under same operating conditions on same engine). The combustion of the charge commences when the piston approaches to TDC.

The second fuel injected into recompressed burnt gas can be burnt in the second combustion process. In other words combustion process of the second fuel takes place in an internal full EGR (Exhaust Gas Recirculation) of the first combustion. This second combustion process was the special feature of the proposed Six Stroke DI Diesel Engine.

3.1.6 Exhaust stroke

The exhaust valve begins to open when the power stroke is about to complete. A pressure of 4-5 kgf/cm2 at this instant forces about 60% of burnt gases into the exhaust manifold at high speed. Much of the noise associated with automobile engine is due to high exhaust velocity. The remainder of burnt gases is cleared of the swept volume when the piston moves from TDC to BDC. During this stroke pressure inside the cylinder is slightly above the atmospheric value. Some of the burnt gases are however left in the clearance space. The exhaust valve closes shortly after TDC.

The inlet valve opens slightly before the end of exhaust stroke and cylinder is ready to receive the fresh air for new cycle. Since from the beginning of the intake stroke the piston has made six strokes through the cylinder (Three up And Three down). In the same period crank shaft has made three revolutions. Thus for six stroke cycle engine there are two power strokes for every three revolutions of crank shaft.















3.2 Performance analysis

3.2.1 Modification over four stroke diesel engine

This six-stroke diesel engine was made from a conventional four-stroke diesel engine with some modification. A sub-shaft was added to the engine, in order to drive a camshaft and injection pumps. The rota¬tion speed of the sub-shaft was reduced to 1/3 of the rotation of an output shaft. To obtain similar valve timings between a four-stroke and a six-stroke diesel engine, the cam profile of the six-stroke diesel engine was modified. In order to separate the fuels, to control each of the injec¬tion timings and to control each injection flow rate in the first and the second combustion processes, the six-stroke diesel engine was equipped with two injection pumps and two injection nozzles. The injection pumps were of the same type as is used in the four-stroke diesel engine.

The nozzle is located near the center of a piston cavity, and has four injection holes. For the six-stroke diesel engine, one extra nozzle was added on the cylinder head. This extra nozzle was of the same design as that of the four-stroke engine.

Fig 14 Volume “Angle diagram for six stroke engine

Diesel fuel for the first combustion process was injected through this extra nozzle, and methanol for the second combustion process was injected through the center noz¬zle. Here, we denoted the injection timing of the four¬ stroke diesel engine as Xi. The injection timings of the first and second combustion strokes for the six-stroke diesel engine are shown as Xi I and Xi II, respectively. Crank angle X was measured from the intake BDC. In the six-stroke engine, crank angle of the first combustion TDC is 180 degrees. The second combustion TDC is 540 degrees.

Specifications of the test engines are shown in Table 1. The conventional four-stroke diesel engine that was cho¬sen as the basis for these experiments was a single cylin¬der, air cooled engine with 82 mm bore and 78 mm stroke. The six-stroke engine has the same engine speci¬fications except for the valve timings. However, the volumetric efficiency of the six-stroke engine showed no significant difference from that of the four-stroke engine.

Characteristics of the six-stroke diesel engine were com¬pared with the conventional four-stroke diesel engine. In this paper, the engine speed (Ne) was fixed at 2,000 rpm. Cylinder and line pressure indicators were equipped on the cylinder head. NO concentration was measured by a chemiluminescence™s NO meter, and soot emission was measured by a Bosch smoke meter.

The physical and combustion properties of diesel fuel and methanol are shown in Table. 2. Since combustion heats of diesel fuel and methanol are different, injection flow rates of the first and the second combustion pro¬cesses are defined by the amount of combustion heat. Here, the supplied combustion heat for the first combus¬tion process is denoted by QI. The second combustion stroke is denoted by QII. The ratio of QII to Qt (Qt = QI+QII) supplied combustion heat per cycle) is defined as the heat allocation ratio aH: aH = QII = QII
QI +QII Qt




Table 1. Specifications of the test engine:
Four stoke Six stroke
Diesel Engine Diesel Engine
Engine type DI, Single cylinder, Air cooled, OHV
Bore x Stroke [mm] 82 x 78
Displacement [cc] 412
Top Clearance [mm] 0.9
Cavity Volume [cc] 16
Compression ratio 21
Intake Valve Open 100 BTDC 70 BTDC
Intake valve Close 1400 BTDC 1450 BTDC
Exhaust Valve Open 1350 ATDC 1400 ATDC
Exhaust Valve Close 120 ATDC 30 ATDC
Valve Overlap 220 100
Rated power 5.9 kW /3000rpm
Base Engine ----------------




Table 2. Physical and combustion properties of diesel fuel and methanol:
Diesel Fuel Methanol
Combustion heat [MJ/kg] 42.7 19.9
Cetane number 40-55 3.0
Density [kg/m2] 840 793
Theoretical air-fuel ratio 14.6 6.5




3.3 Performance of six stroke diesel engine
3.3.1 Comparison with four stroke diesel engine

A four-stroke engine has one intake stroke for every two engine rotations. For the six-stroke engine, however, the intake stroke took place once for every three engine rotations. In order to keep the combustion heat per unit time constant, the combustion heat supplied to one six-stroke cycle should be 3 or 2 times larger than that of the four-stroke engine.

There are many ways to compare performance between the four-stroke and six-stroke engines. For this paper, the authors have chosen to compare thermal efficiency or SFC at same output power. If the thermal efficiency was the same in both engines, the same output power would be produced by the fuels of equivalent heats of combus¬tion.

Therefore, in order to make valid comparison, fuels supplied per unit time were controlled at the same value for both engines and engine speeds were kept constant. In this section, fuel supplied for the engines was only a diesel fuel. Performance of the six-stroke engine was compared with that of the four-stroke engine under vari¬ous injection timings.


Detailed conditions for comparison of the four-stroke and six-stroke engines are listed in Table. 3. The heat allocation ratio of the six-stroke engine was set at aH = 0.5. Injection flow rate of fuel was Qt4 = 0.50 KJ/cycle for the four-stroke engine and Qt6 = 0.68 KJ/cycle for the six stroke engine. For six stroke engine, it meant that ¬the amount of 0.34KJ was supplied at each combustion process.



At the viewpoint of combustion heat, 0.75 KJ/cycle of heat should be supplied for the six stroke engine to make the equivalence heat condition. However diesel fuel of 0.68 KJ/cycle was supplied here because of difficulties associated with methanol injection.

Injection timing of the four-stroke engine was changed from 160 degrees (200BTDC) to 180 degrees (TDC). For six -stroke engine, the injection timing of the first com¬bustion process was fixed to 165 degrees (15°BTDC) or 174 degrees (6°BTDC), and the second injection timing was changed from 520 degrees (2000 BTDC) to 540 degrees (TDC).


Fig 15 Valve timing diagram four stroke engine




Table 3. Detailed conditions of comparison between the four stroke and six stroke diesel engines and performance of engine

Engine Parameters Four Stroke
Diesel Engine Six Stroke
Diesel Engine
Engine Speed Ne [rpm] 2007 2016
Supplied combustion heat per cycle
Qt [KJ/cycle]
0.50
0.68
Supplied combustion heat per unit time Ht [KJ/s]
8.36
7.62
Intake air flow per cycle
Ma [mg/cycle]
358.7
371.4
Injection quantity per cycle
Mf [mg/cycle]
11.8
16

Excess air ratio
2.40
1.83
Intake air flow per unit time
Ma [g/cycle]
6.00
4.16
Injection quantity per unit time
Mf [g/sec]
0.197
0.179
Brake torque Tb [N-m] 15.52 15.28
Brake power Lb [KW] 3.26 3.24
BSFC. b [ g / KW-h] 217.9 520.3
IMEP Pi [Kgf / cm2] 5.94 4.37
Indicated torque Ti [N-m] 19.10 18.71
Indicated power Li [KW] 4.01 3.75
ISFC bi [g / KW-h ] 177.2 163.3

Indicated torque of the six-stroke engine is almost same level with that of the four-stroke engine under various injection timings. NO concentration in exhaust gas of the six-stroke engine was lower than that of the four-stroke engine. NO emissions from both engines were reduced by the retard of injection timing. The effect of retard in the second injection timing of the six-stroke engine was similar to that of the retard in the four-stroke engine.
For the six-stroke engine, from the comparison between Xi I = 165 degrees (15°BTDC) and Xi I = 174 degrees (6°BTDC), it seemed that the NO reduction effect appeared with the timing retard in the first combustion process.
Soot emission in the exhaust gas of the four-stroke engine was low level and it was not affected by the timing retard of injection. However, the level of soot emission from the six-stroke engine was strongly affected by the timing of the second injection. When the injection timing was advanced from 528 degrees (12° BTDC), it was con-firmed that the soot emission was lower than that of the four-stroke engine.

From numerical analysis, it was considered that the soot formed in the first combustion process was oxidized in the second combustion process. On the contrary, when the injection timing was retarded from 528 degrees (12° BTDC), soot emission increased with the timing retard. Then, it was considered that the increased part of the soot was formed in the second combustion process because an available period for combustion was shortened with the retard of injection timing.

Experimental conditions were Xi = Xi I = 170 degrees (100 BTDC) and XiII=530 degrees (100 BTDC). The heat allocation ratio of six stroke engine was aH=0.5.

The cylinder temperature and heat release rate were calculated from the cylinder pressure. The pattern of heat release rate in the first combustion stroke of the six-stroke engine was similar to that of the heat release rate of the four-stroke engine. It was the typ¬ical combustion pattern that contained a pre-mixed com¬bustion and diffusion combustion. On the other hand, since an increase of cylinder temperature in the second combustion process was caused by the compression of the burned gas formed in the first combustion stroke, a pre-mixed combustion in the second combustion process was suppressed by a short ignition delay.
The maximum cylinder temperature in the first combustion process was lower than that in the four-stroke engine. It was caused by smaller amount of fuel which was injected in the first combustion process. Considering these results, it was proved that NO concentration in the exhaust gas was reduced by the decrease of the maximum cylinder temperature in the first combustion process and EGR effect in the second combustion process.

The performance of these two engines could be compared by Table. 3. Since BSFC of the six-stroke engine obtained by the brake power suffered, SFC is compared with ISFC for the Xi = 163 degree (170 BTDC), ISFC of the four-stroke engine was 177.2 g/KW-h.

On the other hand, for the Xi I = 165 degrees (15° BTDC) and Xi II = 523 degrees (170 BTDC), I.S the six-stroke engine was 163.3 g/KW-h. i.e. ISFC of the six-stroke engine was slightly lower than that of the four-stroke engine.

It was considered that this advantage in ISFC was caused by a small cut-off ratio of constant pressure com¬bustion. Because, in the six-stroke engine proposed here, the fuel divided into two combustion processes resulted in a short combustion period of each combustion process. Furthermore, in the reduction of NO emission, the six-stroke engine was superior to the four-stroke engine.

3.3.2 Effect of heat allocation ratio

Injection conditions were Xi I = 170 degrees (1000 BTDC) and Xi II = 530 degrees (100 BTDC). Both fuels in the first and second combustion processes were diesel fuel. Total fuel at the combustion heat basis was Qt = 0.68 KJ/cycle. It meant a high load in this engine because the total excess air ratio was 1.83 as previously shown in Table 3.

The maximum value of the indicated torque appeared around aH = 0.5 NO concentration in exhaust gas was reduced by an increase of heat allocation ratio. In other words, NO emission decreased with an increase of the fuel of the second combustion process.

In the case of aH = 0.5, there is a relatively long ignition delay in the first combustion process and pre-mixed com¬bustion was the main combustion phenomena in it. NO of high concentration was formed in this pre-mixed combus¬tion process. On the other hand, in the case of aH = 1, diffusion combustion was the main combustion phenom¬ena and NO emission was low.

Soot emission in exhaust gas increased with an increase of heat allocation ratio. Since the injection flow rate in the second combustion process increased with an increase of the heat allocation ratio, the injection period increased with an increase of the heat allocation ratio. It caused the second combustion process to be long, and unburnt fuel that was the origin of soot remained after the second combustion process.

The heat release rates on aH = 0.15 and aH = 0.85. For aH =0.15, since injection flow rate in the first combustion process was high and injection period in it was long, the combustion period in the first combustion process became long as compared with case of aH = 0.85. On the other hand, for aH = 0.85, the combustion period in the second combustion process became long as compared with case of aH=0.15. It was also observed that the long combustion periods in both the first and second combustion were caused by the long dif¬fusion combustion. Further, diffusion combustion was the main combustion phenomena of the second combustion process.


When the heat allocation ratio was 0.85, the ratio of heat release rates between the first and second combustion should be 15: 85, however the actual ratio obtained from the figure was 46: 54. This inconsistency was caused from the drift of the base lines of the heat release dia¬grams. For aH = 0.15, the actual ratio of heat release rates was 73: 27 with the similar reason.

The cylinder temperature for the aH = 0.15 condition was higher than that of the aH = 0.85 condition. This could be explained as follows. In the first combustion stroke, since the injection flow rate of aH = 0.15 was higher than that of aH = 0.85, the combustion temperature for the aH = 0.15 condition was higher than that of aH = 0.85. In the second compression stroke, since the high temperature burned gas was re-compressed, the temperature of aH = 0.15 was also higher than that of aH = 0.85.

As a result, the temperature at the beginning of the second combustion stroke was high in aH = 0.15 condition as compared with aH = 0.85 condition. At the later stage of the second com¬bustion, however, the opposite relationship between these two temperatures were observed, because the injection flow rate of the second combustion process was low in aH = 0.15 condition.
The maximum temperatures in the first and second com¬bustion process decreased with an increase of the heat allocation ratio. Then, it could be concluded that the reduction of NO concentration with the heat allocation ratio, was caused by the decrease of the cylinder temperature.







3.4 Performance of the dual fuel six stroke diesel engine
3.4.1 Comparison with diesel fuel six stroke engine
Operating conditions of comparison between the diesel fuel and the dual fuel six-stroke engines are shown in Table. 4. Experimental conditions were Xi I= 170 degrees (100 BTDC), Xi II = 530 degrees (10o BTDC) and aH = 0.5.

In dual fuel six-stroke engine, diesel fuel and methanol were supplied into first and second combustion process, independently. Combustion heats supplied per one cycle of the diesel fuel and dual fuel six-stroke engines were same. The combustion heat supplied per one cycle was selected as Qt = 0.43 KJ/cycle under the middle load con¬dition. Performance of the dual fuel six-stroke engine was compared with the diesel fuel six-stroke engine under various injection timings in the second combustion pro¬cess. Indicated torques of both engines was revealed constant around 15 N-m. As a result, it could be concluded that states of combustion of the diesel fuel and the dual fuel six-stroke engines had similar contributions on the engine performance. NO emissions from the dual fuel six-stroke engine were lower than those of the diesel fuel six-stroke engine. This effect appeared prominently at the advanced injection timing of the second combustion. Further, NO concentrations of both engines were reduced by the injection timing retard in the second combustion.

Fig 16 Torque- Angle diagram for six stroke engine

Soot emission in the exhaust gas of the diesel fuel six¬ stroke engines increased with a retard of the injection tim¬ing in the second combustion. For the dual fuel six-stroke engine, the exhaust level of soot was very low under vari¬ous injection timings of the second combustion process. Soot was formed clearly by the combustion of diesel fuel in the first combustion process and it was oxidized in the second combustion process. Considering these results, it was possible to estimate that soot was almost oxidized by methanol combustion in the second combustion process. This estimation is supported by a dual fuel diesel engine operated with diesel fuel methanol.
The combustion heat supplied per one cycle was selected as Qt = 0.68 KJ/cycle under the high load condition. Indicated torques of both engines was also revealed constant around 20 N-m. NO concen¬tration had the same tendency as the cases of the middle load. Soot emission level of the diesel fuel six-stroke engine was high in this high load condition. For the dual fuel six-stroke engine, however, soot was very low under various injection timings of the second combustion pro¬cess.

The performance of these engines was compared in Table. 4. For the second combustion process, since com¬bustion heats of diesel fuel and methanol were different, injection quantities of both engines were different. BSFC and ISFC of the dual fuel six-stroke engine was sensibly higher than that of the diesel fuel engine. To compare the performance of these engines, injection quantity of both engines was defined by an amount of combustion heat, and SFC should be calculated from it. As a result, indicated specific heat consumption of the diesel fuel six-stroke engine was 5.59 MJ/KW-h, and that of the dual fuel six-stroke engine was 5.43 MJ/KW-h. For the high load conditions shown in Table. 5, the similar advantage of the dual fuel six-stroke engine was observed.







Table 4. Detailed conditions of comparison between the diesel fuel and dual fuel diesel engines and performance of engines under aH = 0.5 and middle load
Diesel Fuel Six Stroke Diesel Engine Dual Fuel Six Stroke
Diesel Engine
Engine Speed Ne [rpm] 2016 2003
Supplied combustion heat per cycle
Qt [KJ/cycle]
0.43

Injection quantity per cycle
(First Combustion Stroke)
Mf1 [mg/cycle] 5.0
(Diesel Fuel)

Injection quantity per cycle
(Second Combustion Stroke)
Mf2 [mg/cycle] 5.0
(Diesel Fuel) 10.7
(Methanol)
Excess air ratio 2.98 3.15
Brake torque Tb [N-m] 3.14 3.14
Brake power Lb [KW] 0.66 0.66
B.S.F.C. b [ g / KW-h] 610.9 952.9
I.M.E.P. Pi [Kgf / cm2] 3.43 3.53
Indicated torque Ti [N-m] 16.70 15.12
Indicated power Li [KW] 3.1 2.77
I.S.F.C. bi [g / KW-h ] 130.1 198.4
Indicated specific heat consumption
biâ„¢ [MJ /KW-h]
5.59
5.43


In order to confirm the advantage of dual fuel six-stroke engine, the performance of these engines was compared with four-stroke engine as shown in Table. 6. NO concen¬trations of the diesel fuel and the dual fuel six-stroke engines were improved with 85 - 90% as compared with that of the four-stroke engine. Soot emission of the diesel fuel six-stroke engine was much higher than that of the four-stroke engine. However, for the dual fuel six-stroke engine, soot level was very low.

Furthermore, the indi¬cated specific heat consumption of the diesel fuel and dual fuel six-stroke engine were lower than that of the four-stroke engine. Especially, for the dual fuel six-stroke engine, the indicated specific heat consumption was improved with 15% as compared with that of the four¬ stroke engine. From these results, it could be confirmed that the dual fuel six-stroke engine was superior to the diesel fuel six-stroke engine, and also it was superior to the four-stroke engine.






Table 6. Percentage improvements of exhaust emission and specific heat consumption
Four Stroke Diesel Engine Six Stroke Diesel Engine Dual Fuel Six Stroke Engine
NO [ppm]
( % improvement)
768 113
(85.3%) 90.5
(88.2%)
Soot [%]
(%improvement)
6.8 28.8
(- 323.5%) 0
(100%)
Indicated specific heat consumption biâ„¢ [MJ/KW-h]
(% improvement)
7.51
6.61
(12.0%)
6.37
(15.2%)




Table 5. Detailed conditions of comparison between the diesel fuel and dual fuel diesel engine and performance of engines under aH =0.5 and high load
Six Stroke Diesel Engine Dual Fuel Six Stroke Engine
Engine Speed Ne [rpm] 2016 2006
Supplied combustion heat per cycle
Qt [kJ/cycle]
0.68

Injection quantity per cycle
(First Combustion Stroke)
Mf1 [mg/cycle] 8.0
(Diesel Fuel)

Injection quantity per cycle
(Second Combustion Stroke)
Mf2 [mg/cycle] 8.0
(Diesel Fuel) 17.2
(Methanol)
Excess air ratio 1.86 1.93
Brake torque Tb [N-m] 6.18 6.08
Brake power Lb [kW] 1.52 1.5
B.S.F.C. b [ g / kW.h] 504.0 777.7
I.M.E.P. Pi [kgf / cm2] 4.56 4.75
Indicated torque Ti [N-m] 21.68 20.38
Indicated power Li [kW] 3.45 2.98
I.S.F.C. bi [g / kW.h ] 155.5 236.2
Indicated specific heat consumption
biâ„¢ [MJ /kW.h]
6.61
6.37








3.4.2 Effect of injection timing

Performance of the dual fuel six-stroke engine under various injection timings in the second combustion process was investigated on middle and high load. Experimental conditions were Xi I = 170 degrees (100 BTDC) and aH = 0.5.

Perfor¬mance of the dual fuel six-stroke engine under both load conditions had the similar tendency with the timing retard. NO concentrations in the high load condition were higher than those of the middle load condition. However, soot emission levels of both load conditions were extremely low under various injection timings of the sec¬ond combustion.


3.4.3 Effect of heat allocation ratio

Performance of the dual fuel six-stroke engine under various heat allo¬cation ratios was investigated on middle and high load. Injection conditions were Xi I = 170 degrees (100 BTDC) and Xi II = 530 degrees (100 BTDC). Since the combus¬tion heat of methanol was low, experimental range of heat allocation ratio was limited by the smooth operation of the engine. Only the range from aH = 0.25 to 0.75 (on Qt = 0.43 KJ/cycle), and from aH = 0 to 0.5 (on Qt = 0.68 KJ/cycle) could be tested. .

Indi¬cated torque increased with an increase of the heat allo¬cation ratio. NO concentration in exhaust gas was reduced with an increase of the heat allocation ratio. Soot was very low, irrespective of the methanol flow rate. Even if the load condition was high, it was concluded that soot was practically eliminated by a small amount of methanol in the second combustion process (8% of total fuel).

4. ADVANTAGES OF SIX STROKE OVER FOUR STROKE ENGINES

The six stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake stroke, the compression stroke and the Six stroke engine is fundamentally superior to the four stroke because the head is no longer parasitic but is a net contributor to “ and an integral part of “ the power generation within exhaust stroke. The compression ration can be increased because of the absent of hot spots and the rate of change in volume during the critical combustion period is less than in a Four stroke. The absence of valves within the combustion chamber allows considerable design freedom.

4.1 Main advantages of the duel fuel six-stroke engine:

4.1.1 Reduction in fuel consumption by at least 40%:

An operating efficiency of approximately 50%, hence the large reduction in specific consumption. the Operating efficiency of current petrol engine is of the order of 30%. The specific power of the six-stroke engine will not be less than that of a four-stroke petrol engine, the increase in thermal efficiency compensating for the issue due to the two additional strokes.

4.1.2 Two expansions (work) in six strokes:

Since the work cycles occur on two strokes (3600 out of 10800 ) or 8% more than in a four-stroke engine (1800 out of 720 ), the torque is much more even. This lead to very smooth operation at low speed without any significant effects on consumption and the emission of pollutants, the combustion not being affected by the engine speed. These advantages are very important in improving the performance of car in town traffic.

4.1.2 Dramatic reduction in pollution:

Chemical, noise and thermal pollution are reduced, on the one hand, in proportion to the reduction in specific consumption, and on the other, through the engineâ„¢s own characteristics which will help to considerably lower HC, CO and NOx emissions. Furthermore, itâ„¢s ability to run with fuels of vegetable origin and weakly pollutant gases under optimum conditions, gives it qualities which will allow it to match up to the strictest standards.

4.1.3 Multifuel:

Multifuel par excellence, it can use the most varied fuels, of any origin (fossil or vegetable), from diesel to L.P.G. or animal grease. The difference in inflammability or antiknock rating does not present any problem in combustion. Itâ„¢s light, standard petrol engine construction, and the low compression ration of the combustion chamber; do not exclude the use of diesel fuel. Methanol-petrol mixture is also recommended.









5. CONCLUSIONS

The performance of the dual fuel six-stroke engine was investigated. In this dual fuel engine, diesel fuel was sup¬plied into the first combustion process and methanol was supplied into the second combustion process where the burned gas in the first combustion process was re-com¬pressed. The results are summarized as follows.

1. Indicated specific fuel consumption (ISFC.) of the six-stroke engine proposed here is slightly lower than that of the four-stroke engine (about 9% improvement). NO and soot emissions from the six-stroke engine was improved as compared with four-stroke engine under advanced injection timings in the sec¬ond combustion stroke.
2. For the dual fuel six-stroke engine, the timing retard and an increase of heat allocation ratio in the second combustion stroke resulted in a decrease of the max¬imum temperatures in the combustion processes. It caused the reduction of NO emission.
3. For the dual fuel six-stroke engine, soot was practi¬cally eliminated by a small amount of methanol in the second combustion process.
4. From the comparison of the performance between the dual fuel six-stroke and the four-stroke engine, it was concluded that indicated specific heat consump¬tion of the dual fuel six-stroke engine was improved with 15% as compared with the four-stroke engine. NO concentration of the dual fuel six-stroke engine was improved with 90%. Furthermore, soot emission was very low in the dual fuel six-stroke engine.
5. As the fuel in one cycle was divided into two combus¬tion processes and the EGR effect appeared in the sec¬ond combustion process, the decreased maximum cylinder temperature reduced NO concentration in the exhaust gas It was further confirmed that soot formed in the first combustion process was oxidized in the second combustion process .Therefore, a six¬ stroke DI diesel engine has significant possibilities to improve combustion process because of its more control¬lable factors relative to a conventional four-stroke engine. Considering these results, it was confirmed that the dual fuel six-stroke engine was superior to the four-stroke engine.






6. REFERENCES

1. Tsunaki Hayasaki, Yuichirou Okamoto, Kenji Amagai and Masataka Arai
A Six-stroke DI Diesel Engine under Dual Fuel Operation SAE Paper No
1999-01-1500
2. S.Goto and K.Kontani, "A Dual Fuel Injector for Die¬sel Engines", SAE paper, No. 851584, 1985
3. Internal Combustion Engines A book by Mathur & Sharma.
4. Internal Combustion Engines Tata McGraw-hill publications,
Author V Ganesan






7. NOMENCLATURE
Ne : Engine speed
X : Crank angle
Xi : Injection timing of the four-stroke diesel engine
aH : Heat allocation ratio
Q : Supplied combustion heat
Qt : Supplied combustion heat per cycle
P : Cylinder pressure
V : Cylinder volume
Vs : Stroke volume
Pi : Indicated mean effective pressure (LM.E.P)
Ti : Indicated torque
Li : Indicated power
Tb : Brake torque
Lb : Brake power
Ht : Supplied combustion heat per unit time
Ma : Intake air flow per cycle
Ma' : Intake air flow per unit time
Mf : Injection quantity per cycle
Mi : Injection quantity per unit time
: Excess air ratio
b : Brake specific fuel consumption (B.S.F.C.)
bl : Indicated specific fuel consumption (I.S.F.C.)
bi' : Indicated specific heat consumption
SUBSCRIPTS
I: first combustion stroke
II: second combustion stroke
4: four-stroke diesel engine
6: six-stroke diesel engine

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18-06-2010, 06:45 PM
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RE: six stroke engine

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Presented By:
Bhojaraj.B.G
DEPARTMENT OF MECHANICAL ENGINEERING
G M INSTITUTE OF TECHNOLOGY
# 4, P B Road, Davangere “ 577 006
VISVESVARAYA TECHNOLOGICAL UNIVERSITY
BELGAUM “ 590 014


ABSTRACT

Two-stroke and four-stroke engines have ruled for over a hundred years. Australian farmer Malcolm beareâ„¢s ingenious six-stroke power plant has pots of potential waiting to be tapped, particularly for the booming motorcycle industry.
A new four stroke engine head design known as the Beare Head after its designer Malcolm Beare. The Beare Head uses a piston and ports very much like a two stroke engine to replace the over head valve system that is found in four stroke engines today. The four stroke block, pistons and crankshaft remain unaltered. This combination of two stroke and four stroke technology has given the engine its name “ the six stroke engine (2 + 4 = 6).
A number of prototype Beare Heads produced have been the subject of extensive testing and theoretical analysis. Key attributes of the Beare Head are: increased power, increased torque, fewer, lighter reciprocating parts, simpler manufacture.
The Pulse Fuel Injector and Nozzle have been tested. Unlike conventional fuel injectors, this technology uses compressed air to atomize liquid fuel and pre-mix it with air; this increases efficiency and reduces emissions in internal combustion engines.
The Pulse Fuel Injector and Nozzle again can be used together or separately and have wide applications, not o¬nly the automotive field but also in the area of gas turbines, aerospace and waste incineration.

1. INTRODUCTION

Malcolm Beare is 53 year old Australian wheat farmer is indeed an original thinker, in spite of a day job apparently so far removed from the world of mechanics. For the past 23 years, while working his 1300 hectare spread in the sun-drenched outback of South Australia, Malcolm has had plenty of time to reflect on various aspects of his alternative profession. The Beare Engine is a completely new development of the internal combustion engine.
Termed a six-stroke due to the radical hybridization of two- and four-stroke technology, the device achieves increased torque and power output, better fuel economy and cleaner burning with reduced emissions, longer service intervals, and considerably reduced tooling costs when compared with a conventional OHC four-stroke design.
A new four stroke engine head design known as the Beare Head after its designer Malcolm Beare. The Beare Head uses a piston and ports very much like a two stroke engine to replace the over head valve system that is found in four stroke engines today. The four stroke block, pistons and crankshaft remain unaltered. This combination of two stroke and four stroke technology has given the engine its name “ the six stroke engine (2 + 4 = 6).
The prototype six stroke engines already produced have been the subject of extensive testing and theoretical analysis. Key attributes of a six stroke engine include:
¢ Increased power
¢ Increased torque
¢ Fewer, lighter, reciprocating parts
¢ Simpler manufacture

2. THEORY

Actually retarding the upper piston drive has a positive outcome on power output and efficiency largely because it effectively increases compression ratio, reduces the rate of change in volume during the combustion period, opens the exhaust port later, increases the period of valve overlap thus utilizing the exhaust extraction effect and closes the intake port later. The negative effect of this is to increase the amount of energy input to the head, but this is more than compensated by the positive outcomes.
The Six stroke engine is fundamentally superior to the four strokes because the head is no longer parasitic but is a net contributor to - and an integral part of - the power generation within the engine. The Six strokes is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake stroke, the compression stroke, and the exhaust stroke. The compression ratio can be increased because of the absence of hot spots and the rate of change in volume during the critical combustion period is less than in a four stroke. The absence of valves within the combustion chamber allows considerable design freedom.
The reasons for this high torque output are:
(1) The reed valves keep gas velocity high at low throttle openings and prevent spit back through the carburetor.
(2) There is a gain in mechanical efficiency because the cylinder head is returning power to the main crank, unlike a conventional four stroke which suffers parasitic losses from the valve train.
(3) The compression pressure is maintained at low throttle settings because of the stratification of the intake charge keeping the fuel mixture swirling on the outside next to the spark plugs and retaining some exhaust towards the centre. The cranking compression pressure was the same as the standard bike, at 135 PSI.
(4) The effective change in volume of the expansion stroke is actually larger than either two- or four-strokes, which means that more energy is extracted during the combustion process.
3. HOW IT WORKS

Below the cylinder head gasket, everything is conventional, so one advantage is that the Beare concept can be transplanted on to existing engines without any need for redesigning or retooling the bottom end. But the cylinder head and its poppet valves get thrown away. To replace the camshaft and valves, Beare has retained the cam drive belt and fitted an ultra short-stroke upper crankshaft complete with piston, which the belt drives at half engine speed just as it previously drove the cam. This piston drives up and down in a sleeve, past inlet exhaust ports set into the cylinder wall, very much like on a two-stroke: these are all exposed during both inlet and exhaust strokes.
Continuing the two-stroke analogy, two 35mm Mikuni CV crabs mounted on each cylinder feed mixture into it via a reed-valve block, thus preventing exhaust gasses from escaping through the inlet. At the other end of the upper crankshaft is a two-stroke type rotary disc-valve that regulates timing, cutting off the exhaust flow at the appropriate time to stop the gasses returning into the cylinder, thus creating sub-atmospheric pressure during the inlet cycle. This being it's only function, the rotary valve is lightly loaded, reducing lubrication and sealing problems. It does need close tolerances though, which led to warping of the stainless steel disc Malcolm used on his first six-stroke, based on a Honda XL125 farm bike. Replacing the disc with a cast-iron one (on a Mk2 XT500-based version), cured this problem at the expense of extra weight. The Ducati uses hardened anodized aluminum discs, which work well.
During the compression and expansion strokes, the upper piston seals off both ports, leaving the pressure contained between the two pistons, with the lower one a conventional flat-top three-ring design, while the conical upper one (so shaped to aid gas flow during both inlet and exhaust cycles by guiding it towards the ports) has two rings - one compression, one oil. In the combustion phase, twin spark plugs provide ignition via the stock Ducati CDI and a pair of Harley coils - one per cylinder - and not only does the engine run on pure petrol (no need to add oil, because all required surfaces are positively lubricated, in spite of the application of two-stroke technology), it's also happy on low octane unleaded fuel. Obviously there are no valve seats to suffer from lack of lead, and Malcolm says the compression ratio can be increased significantly from the Ducati motors 10.6:1 quite safely because of the lack of hotspots, without problems with detonation. So now the claimed advantages of all this start to come to light - allowing a higher compression while still happy with low octane unleaded make this an efficient and cleaner engine. There are no poppet valves to float or bend (OK, OK - I know this was once a Desmo, but this is a much more cost-effective way of achieving this than expensively machining a set of closing rockers for all the valves in a cylinder head, quite apart from the unwanted inertia such a system still entails)
In turn, this implies a far higher safe rev limit for the six-stroke - 28,000rpm in theory, given the half-engine speed operation of the upper crankshaft, and the fact that GP reed-valve two-strokes peak at 14,000rpm. But Malcolm Beare says the rev limit, as on such two-strokes, depends only on what the main (conventional) crankshaft is able to bear, and he's arbitrarily limited the Ducati-based 6S-V2 to 9,000rpm for that reason, at which point he says (according to computer predictions) 86bhp is delivered at the rear wheel - there aren't too many dynojet rigs out in the Australian outback! Comparisons are hard to make, because of the difficulty of determining the exact cubic capacity of the 6S-V2's six-stroke engine: what began as an elderly Pantah V-twin now has a total 744cc's of compression/expansion volume, and 602cc of inlet/exhaust volume, and instead of absorbing about 10% of engine power in driving the camshafts, the cam belts now deliver about 9% net power to the main crankshaft after combustion via the upper, conical porting piston (see, Desmo power!).
But if you figure that a '97 model Ducati 900SS delivers 73bhp at the rear wheel in stock form, that's quite an impressive claimed power increase.
But there are other, much more significant apparent spin-off benefits from the Beare design. First of these is fuel economy: Malcolm Beare claims his engine is 35% more economical at low revs/throttle openings than an equivalent conventional engine and 13% less thirsty at high rpm/full throttle, in spite of the doubled-up crabs. That should mean fewer hydrocarbon and CO2 emissions, because you're using less fuel to achieve the same performance. Next there's improved torque at lower revs - on both his Yamaha and Ducat-based prototypes Bearer discovered the six-stroke version produced the same torque as a four-stroke 1,000rpm lower down the scale, as well as producing exponentially more torque as revs rose. But in a commercial application, perhaps the most attractive benefit is the reduced number of moving parts, compared to a four-stroke design, so the six should be cheaper to make. Not as few as a two-stroke, but what you appear to be getting here is improved performance and torque, coupled with the inherent advantages of a four-stroke, on the cheap. Finally, as the upper two-stroke piston is driven at half engine speed, it should have twice the life of the lower four-stroke one. Sounds promising...

4. PRINCIPLES OF BEARE HEAD COMBUSTION CYCLE

The following is an simplified description of the combustion process of the Beare Head, and is designed for non-technical types. The images will give automotive engineers clues as to how the process is implemented.

1. INTAKE

The intake stroke happens when the piston is on its downward path with the intake valve open. This action creates suction, drawing atomized fuel, in this case gasoline mixed with air, into the combustion chamber. This is exactly the same action when liquid is drawn into a syringe.
2. COMPRESSION
The compression stroke happens as the piston begins its upward stroke with all the valves in the closed position. This compresses the air-fuel mixture causing it to become more volatile, or explosive.

3. IGNITION

The power stroke begins at a critical moment, just as the air-fuel mixture is at its most compressed. A supercharged voltage is delivered to the spark plugs from the ignition coil, at which point it ignites the fuel mixture. The valves in the engine are still closed during this period. Thus the explosion forces the piston down to turn the engine's crankshaft, delivering the power via the gearbox and clutch to the driving wheels.
4. EXHAUST
The final of the four strokes, as you have not doubt guessed, is the exhaust stroke. The piston is now on its second upward path, and the exhaust valves are now opening, allowing the spent gases to exit the engine via the exhaust pipes. At the top of this stroke the exhaust valves close, the intake valves open, and the whole process repeats - quite rapidly.

5. SPECIFICATION OF SIX STROKE ENGINE

PROTOTYPE 5 - DUCATI BASED
Engine Type Air-cooled opposed-piston rotary- & reed-valve 90° V-twin
Bore x stroke
86 x 57 lower, 60 x 25 upper
Capacity 616cc intake, 575cc compression corrected, 643cc expansion corrected, 592cc exhaust.
616cc intake, 756cc compression, 732cc expansion, 592 cc exhaust
Measurements taken with upper crankshaft 20° retarded
Corrected measurements taken after ports are closed.
Compression ratio 10.6 : 1 (approx)
Fueling
4 x 35mm Mikuni CV carburetors

Ignition

Dual ignition, Ducati CDI & two H-D 12 volt coils
Power
40 bhp at the rear wheel at 5000rpm as tested after Sir Alan Cathcart's test ride. (Computer predicts 86bhp @9000rpm, 41 ft/lb @ 6000rpm)

Valve timing

Intake open 20° BBDC 520° close 60° ABDC 240°
Duration 440° (this is not a mistake)
Maximum port area at 20° ATDC
Exhaust open 40° BBDC 500° close 60° ATDC 60°
Duration 280°
Maximum port area at TDC 0°
Overlap 260° (also not a mistake)
The reed valves control the beginning of intake according to engine demand.
Transmission
Clutch: wet multiplate
Gearbox: 5-speed
Final drive: 520 chain
Frame
Garden gate style 1" square tube space frame
Suspension
41mm FZR Yamaha forks, 50 x 25 RHS steel swing arm, twin Koni dampers
Brakes
Front: twin ÃƒË 300mm floating discs with 4-piston calipers
Rear: single ÃƒË 220mm disc with opposed piston caliper
Tyres
Front 120/70 VR17, Rear 160/60 VR17
Wheelbase
1400mm
Rake/Trail
98mm/23°
Weight
153kg dry
6. COMPARISON OF SIX-STROKE ENGINE WITH FOUR-STROKE ENGINE
1. In a six stroke engine the energy absorption is less because of slower acceleration of reciprocating parts The piston speed of the upper piston is about a quarter of the main piston; therefore its service life should be at least twice that of the main piston.
2. In the Beare design, per single cylinder, the number of parts is 15 compared to a four stroke of approx 40 to 50 parts. Also, to reduce manufacturing costs the head and block can be machined in o¬ne piece.
3. The bottom piston is a standard design and the Beare Head bolts directly o¬nto the engine block, replacing the overhead valves and standard head.
4. It reduces the weight and complexity of the engines head by as much as 50%. Instead of using energy to drive the head, the head actually develops energy for conversion to power back through the timing chains of an engine.
5. Torque is increased by 35% and efficiency increased by the same. This can be achieved by simply unbolting an existing head of a four-stroke engine and then bolting on a Beare Head.
6. Increased torque and power output,
7. Better fuel economy and cleaner burning longer service intervals and considerably reduced tooling costs when compared with a conventional OHC four-stroke design.
¢ Volume-angle diagrams for 4-stroke and 6-stroke engine
The intake begins at 0 degrees on the X-axis. The effect of the additional volume changes that the upper piston has on the volume of the engine is all positive from a thermodynamic point of view. If the engine were a normal 4 stroke the cylinder capacity would be 340cc. Of note - maximum volume at the end of the intake stroke occurs at 173 degrees instead of 180 degrees- the change in volume is 308cc which is less than a 4 stroke (340cc)- yet the total volume at the end of the intake stroke is 415cc as opposed to 375cc for a conventional stroke.
This means that the extra volume is best swept by gas velocities and not mechanical movement, and therefore mechanical input energy is less. Also, maximum volume is before bottom dead centre 173 deg. Consequently valve timing, if the same as a 4 stroke is more radical and is of longer duration in relation to engine volume and hence volumetric efficiency is considerably improved.
The change in volume during the compression stroke is slightly greater than a 4 stroke after the ports are closed. The expansion stroke is much greater than a 4 stroke; both from T.D.C. to B.D.C. and from T.D.C. till the exhaust port is open. It is possible to leave the opening of the exhaust port later than in a 4 stroke because maximum volume is not reached until after B.D.C.-548 deg. Instead of 540 deg. Hence the 6 stroke system is better from a thermodynamic point of view because more energy is extracted from the expansion process.
During the critical combustion period the rate of change in volume in the 6 stroke is less than a 4 stroke. Minimum volume is not reached until after T.D.C., at 361 deg. This is because of the phasing of the upper piston. It is retarded in reaching its T.D.C. until 20 deg. after T. D.C. (380). This is much better from a thermodynamic view in that combustion occurs at a more constant volume; hence ignition timing is not as critical as in a 4 stroke. There is room in the combustion chamber for up to 4 spark plugs and two direct injectors if needed.
¢ Pressure volume diagrams for 4-stroke and 6-stroke
¢ TORQUE ANGLE DIAGRAMS
¢ PHASE CHANGE
¢ COMPARISON CHART

7. GALLERY

DISC VALVE
The piston is half way up on the exhaust stroke. When the piston reaches TDC with the ports fully open, the disk will begin to cut off the exhaust. The valve runs clockwise.
CYLINDER HEAD FROM BELOW
CYLINDER HEAD “UPPER VIEW
UPPER CRANK
UPPER CRANK WITH PISTON

8. THERMODYNAMIC ADVANTAGES

The intake begins at 0 degrees on the X-axis. The effect of the additional volume changes that the upper piston has on the volume of the engine is all positive from a thermodynamic point of view. If the engine were a normal 4 stroke the cylinder capacity would be 340cc. Of note - maximum volume at the end of the intake stroke occurs at 173 degrees instead of 180 degrees- the change in volume is 308cc which is less than a 4 stroke (340cc)- yet the total volume at the end of the intake stroke is 415cc as opposed to 375cc for a conventional stroke.
This means that the extra volume is best swept by gas velocities and not mechanical movement, and therefore mechanical input energy is less. Also, maximum volume is before bottom dead centre 173 deg. Consequently valve timing, if the same as a 4 stroke is more radical and is of longer duration in relation to engine volume and hence volumetric efficiency is considerably improved.
The change in volume during the compression stroke is slightly greater than a 4 stroke after the ports are closed. The expansion stroke is much greater than a 4 stroke; both from T.D.C. to B.D.C. and from T.D.C. till the exhaust port is open. It is possible to leave the opening of the exhaust port later than in a 4 stroke because maximum volume is not reached until after B.D.C.-548 deg. Instead of 540 deg. Hence the 6 stroke system is better from a thermodynamic point of view because more energy is extracted from the expansion process.
During the critical combustion period the rate of change in volume in the 6 stroke is less than a 4 stroke. Minimum volume is not reached until after T.D.C., at 361 deg. This is because of the phasing of the upper piston. It is retarded in reaching its T.D.C. until 20 deg. after T. D.C. (380). This is much better from a thermodynamic view in that combustion occurs at a more constant volume; hence ignition timing is not as critical as in a 4 stroke. There is room in the combustion chamber for up to 4 spark plugs and two direct injectors if needed.
The change in volume during the exhaust stroke is less than a 4 stroke. This means that the negative pumping work is less than a 4 stroke. Extractive gas velocity is very important. Easily accomplished at T.D.C. with a fully open exhaust port.
The design with 4 intake ports fed by 2 reed blocks per cylinder allows the use of several different intake manifold types:
(1) 4 separate manifolds fed by 4 carburetors or injector bodies, of various length and diameters or all equal length and diameter.
(2) 2 separate manifolds bifurcated to each cylinder so that each has its own carburetor or injector body, with various lengths and diameters.
(3) 2 separate manifolds bifurcated to each cylinder in turn, so that each cylinder is fed by 2 carburetors in turn even though the system has a total of 2 carburetors or injectors, with various length and diameter runners..
(4) 3 intake manifolds, with 3 carburetors or injector bodies, 1 bifurcated to each cylinder with long small diameter runners, the other 2 with short large diameter runners.
The design can cope with various runner diameters and lengths because the reed valves allow any positive pressure pulses to pass through and cancel any negative ones, as well as providing good secondary atomization. Hence at low revs the long thin runners are in tune and at higher revs the shorter fatter ones take over with no need to shut down the long thin ones or visa versa as would be necessary with a normal 4 stroke. Swirl is in one direction at low revs and moves to tumble when the flows are in balance reverting to swirl in the other direction as the short fat ones predominate. A good spread of torque is achieved.
9. CONCLUSION
a. In a six stroke engine the energy absorption is less because of slower acceleration of reciprocating parts The piston speed of the upper piston is about a quarter of the main piston; therefore its service life should be at least twice that of the main piston.
b. In the Bearer design, per single cylinder, the number of parts is 15 compared to a four stroke of approx 40 to 50 parts. Also, to reduce manufacturing costs the head and block can be machined in o¬ne piece.
c. The bottom piston is a standard design and the Bearer Head bolts directly o¬nto the engine block, replacing the overhead valves and standard head.
d. It reduces the weight and complexity of the engines head by as much as 50%. Instead of using energy to drive the head, the head actually develops energy for conversion to power back through the timing chains of an engine.
e. Torque is increased by 35% and efficiency increased by the same. This can be achieved by simply unbolting an existing head of a four-stroke engine and then bolting on a Bearer Head.
f. Increased torque and power output.
g. Better fuel economy and cleaner burning Longer service intervals and considerably reduced tooling costs when compared with a conventional OHC four-stroke design

10. REFERENCES

1. http://www.autocarindia.com
2. http://www.sixstroke.com
3. http://www.dynobike.com
4. http://www.delphi.com
5. http://www.engineersedge.com
6. http://www.mooter.com
7. http://www.howstuffworks.com
8. Popular Mechanics Magazine
9. Auto car India Magazine
10. Applied Thermodynamics by Rajput
11. Automobile Engineering by Dr. Kripal singh
12. Automobile engineering by G.Nagula
13. Mechanical Engineering science by K.R.Gopalakrishna
14. http://www.seminarprojects.com


CONTENTS


1. INTRODUCTION¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..1


2. THEORY¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦2


3. HOW IT WORKS¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..3


4. PRINCIPLES OF BEARE HEAD COMBUSTION CYCLE¦¦¦6


5. SPECIFICATION OF SIX STROKE ENGINE¦¦¦¦¦¦¦¦10

6. COMPARISON OF SIX-STROKE ENGINE WITH FOUR- STROKE ENGINE¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.......12


7. GALLERY¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.. 20

8. THERMODYNAMIC ADVANTAGES¦¦¦¦¦¦¦¦¦¦...23

9. CONCLUSION¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦25


10. REFERENCES¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..26

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24-06-2010, 11:55 AM
Post: #8
RE: six stroke engine
SIX STROKE ENGINES VELOZETA MODEL

Presented By,
SHAIK NIZAMUDDIN
03-06-6048
MECHANICAL 4/4


Introduction

Two different approaches of six stroke engines
First approach
There is two additional strokes by the main piston as fifth and sixth stroke
Second approach
It uses a second opposed piston which moves at half the cyclical rate of the main piston

History of six stroke engines

First Category
1. Griffin six stroke engine
2. Bajulaz six stroke engine
3. Crower six stroke engine
4. Velozeta six stroke engine
Second Category
1. Beare head six stroke engine
2. Charge pump engine




Velozetaâ„¢s six stroke engine

A four stroke Honda engine is altered to form the six stroke engine
First four strokes are same as a conventional four stroke engine
In the fifth stroke, air is sucked in to the cylinder
In the sixth stroke, a mixture of air and unburned gases leaves out.


Engine parts modified

1. Camshaft / Crankshaft Sprockets:-
Crank has 1080 degrees of rotation for 360 rotation of camshaft
Hence their corresponding sprockets are having teeth ratio 3:1
34 teeth sprocket of camshaft in the four stroke is replaced by 42 teeth sprocket
17 teeth crankshaft sprocket is replaced by 14 teeth sprocket


2.Cam lobes:-

360 degrees of cam has divided into 60 degrees among six strokes
Inlet valve is opened in the first stroke only and the exhaust valve, in the fourth, fifth and sixth strokes by the exhaust valve cam.
The exhaust valve cam is double lobed

3.Valve Timing:-

IVO at 0 degree at TDC
IVC at 25 degree after BDC
EVO at 0 degree at BDC which was 25 degree before BDC in the original engine
EVC at 10 degree before TDC
Air inlet reed valve is opened in the fifth stroke and then for the sixth stroke exhaust valve is opened

4.Secondary Air Induction System:-

It supplies air which is used in the fifth and sixth stroke
During the fifth stroke air is sucked into the cylinder through a reed valve provided on the secondary air induction line
In the sixth stroke a second reed valve at the exhaust manifold opens and removes the mixture of air and unburned gases

Working of the engine

First stroke:- During the first stroke the inlet valve (6) opens and air-fuel mixture from carburetor is sucked into the cylinder through the inlet manifold (2).




Second stroke:-

During the second stroke, piston moves from BDC to TDC, both the inlet valve (6) and exhaust valve (11) are closed and the air-fuel mixture is compressed. The compression ratio of the modified engine is same as that of the original four stroke Honda engine 9:1.
Third stroke:-


During the third stroke, power is obtained from the engine by igniting the compressed air- fuel mixture using a spark plug (14). Both valves remain closed. Piston moves from TDC to BDC.

Fourth stroke:-

During the fourth stroke, the exhaust valve (11) and the reed valve (23) opens to remove the burned gases from the engine cylinder. Piston moves from BDC to TDC.
Fifth stroke:-
During the fifth stroke, the exhaust valve (11) remains open and the reed valve (23) closes. Fresh air from the air filter (24) enters the cylinder through the secondary air induction line (21) provided at the exhaust manifold (13). The reed valve (22) opens.
Sixth stroke:-
During the sixth stroke, the exhaust valve (11) remains open. The air sucked into the cylinder during the fifth stroke is removed to the atmosphere through the exhaust manifold (13). The reed valve (23) opens and the reed valve (22) closes.

Advantages

Reduction in fuel consumption
Reduction in pollution normally up to 65%
Better scavenging and more extraction of work per cycle
Lower engine temperature - easy to maintain the optimum engine temperature level for better performance
The engine doesâ„¢t require any basic modification to the existing engines. All technological experience and production methods remain unaltered
Higher overall efficiency

Conclusion

The six stroke engine modification promises dramatic reduction of pollution and fuel consumption of an internal combustion engine. The fuel efficiency of the engine can be increased and also the valve timing can be effectively arranged to extract more work per cycle. Better scavenging is possible as air intake occurs during the fifth stroke and the exhaust during the sixth stroke. Due to more air intake, the cooling system is improved. It enables lower engine temperature and therefore increases in the overall efficiency.


Attached File(s)
.ppt  VELOZETA MODEL-Six Stroke Engine.ppt (Size: 786 KB / Downloads: 309)

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11-07-2010, 09:53 PM
Post: #9
RE: six stroke engine
more info abt six stroke engine
29-10-2010, 03:47 PM
Post: #10
RE: six stroke engine

.doc  SIX STROKE CYLINDER.doc (Size: 108.5 KB / Downloads: 192)
SIX STROKE ENGINE
BY

AHER MAYUR.A
ROLL NO:-43
T.Y.M.E-1
MET, BKC.
POLY.


ABSTRACT:

Uptil now, mainly three types of engines running on otto cycle were developed , namely 2-stroke, 4-stroke and the rotary engines. However rotary engines were not widely used due to its disadvantage. Thus, for over hundred years the basic working concept of 2 and 4 stroke engines has remained same with some minor improvements.
The latest breakthrough in this field is the concept of a “SIX – STROKE” engine. The brain-child of an ordinary Australian automobile enthusiast wheat farmer, may provide for a path to achieve greater output from the engine, in today’s world of fast depleting natural resources. His concept of a fusion of 2- stroke and a 4- stroke operations within the same cylinder of an engine is surely a promising one. This could be a stepping stone for researchers to carry out further developments in this extremely competitive field.
28-12-2010, 03:18 PM
Post: #11
RE: six stroke engine



.doc  6_stroke_engine.doc (Size: 797.5 KB / Downloads: 405)
ABSTRACT

The increasing demands for low emissions and low fuel consumption in modern combustion engines requires improved methods for combustion process. The Beare Head is a new type of six-stroke engine head design known as the “Beare Head” after its designer, Malcolm Beare. The Beare Head uses a piston and ports very much like a two stroke engine to replace the overhead valve system that is found in four stroke engines today. The four-stroke block, piston and crankshaft remain unaltered. This combination of two stroke and four-stroke technology has given the technology its name the “six stroke engine”.
Six Stroke engine, the name itself indicates a cycle of six strokes out of which two are useful power strokes. According to its mechanical design, the six-stroke engine with external and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: combustion and an air heating chamber, both independent from the cylinder. In this the cylinder and the combustion chamber are separated which gives more freedom for design analysis. Several advantages result from this, one very important being the increase in thermal efficiency.
It consists of two cycles of operations namely external combustion cycle and internal combustion cycle, each cycle having four events. In addition to the two valves in the four stroke engine two more valves are incorporated which are operated by a piston arrangement.
The Six Stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake stroke and the compression stroke. The main advantages of six stroke engine includes reduction in fuel consumption by 40%, two power strokes in the six stroke cycle, dramatic reduction in pollution, adaptability to multi fuel operation.Six stroke engine’s adoption by the automobile industry would have a tremendous impact on the environment and world economy.




INTRODUCTION:

The majority of the actual internal combustion engines, operating on different cycles have one common feature, combustion occurring in the cylinder after each compression, resulting in gas expansion that acts directly on the piston (work) and limited to 180 degrees of crankshaft angel.
According to its mechanical design, the six-stroke engine with external and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: Combustion, does not occur within the cylinder but in the supplementary combustion chamber, does not act immediately on the piston, and it’s duration is independent from the 180 degrees of crankshaft rotation that occurs during the expansion of the combustion gases (work).
The combustion chamber is totally enclosed within the air-heating chamber. By heat exchange through the glowing combustion chamber walls, air pressure in the heating chamber increases and generate power for an a supplementary work stroke. Several advantages result from this, one very important being the increase in thermal efficiency. IN the contemporary internal combustion engine, the necessary cooling of the combustion chamber walls generate important calorific losses.

ANALYSIS OF SIX STROKE ENGINE:

Six-stroke engine is mainly due to the radical hybridization of two- and four-stroke technology. The six-stroke engine is supplemented with two chambers, which allow parallel function and results a full eight-event cycle: two four-event-each cycles, an external combustion cycle and an internal combustion cycle. In the internal combustion there is direct contact between air and the working fluid, whereas there is no direct contact between air and the working fluid in the external combustion process. Those events that affect the motion of the crankshaft are called dynamic events and those, which do not effect are called static events.


07-01-2011, 09:26 PM
Post: #12
RE: six stroke engine
Introduction

We have heard about two and four stroke engines. Two stroke engines got its name from the fact that the required strokes are completed in one revolution. In short there is one power stroke in one revolution. In the case of four stroke engines the four strokes are completed in two revolutions, or there is a power stroke in two revolutions. Then how about a six stroke engine. The name of the engine has nothing to do with the number of revolutions or anything of that sort. This engine got its name due to its construction. A six stroke engine derived its name from the fact that it is a mixture of two and four stroke engine. This engine is a radical hybridization of two and four stroke engines. This engine combines the top portion of two stroke engine and the bottom rather the middle section of a four stroke engine.


.doc  6 stroke engines.doc (Size: 82.5 KB / Downloads: 225)

These types of engines have many advantages compared to OHC four stroke engines. They are as follows
1) Increased torque and power output
2) Better fuel economy
3) Cleaner burning with reduced emission
4) Longer service intervals
5) Reduced tooling costs

Six stoke engines were developed in the year 1998 by Malcolm Beare. This technology is under going tremendous research works for improving the six stroke or Beare technology as it is popularly known. This type of engine is not commonly available because of two main reasons
1. This technology is patented by Ducati
2. Research works are going on for improvement of this technology





Construction and Working

The six stroke engine basically works just like a four stroke engine. The major difference is in the construction. The major drawbacks of conventional engines were poppet valves, its basic problems being and - inertia, inhibiting flow especially the exhaust valve hot-spot in the combustion chamber. So a six stroke engine was simplified with the objective of improving efficiency and increasing performance compared to a conventional engine by overcoming the drawbacks of poppet valves, by means of a rotary valve application to four-stroke engine. Of course, a two-stroke doesn't suffer such problems as it had no poppet valves. So these drawbacks were resolved by he basic taking the components of a rotary disc induction two-stroke engine, and grafting them on to a four-stroke to produce the best of both worlds. Below the cylinder head gasket, everything is conventional, so one advantage is that the Beare concept can be transplanted on to existing engines without any need for redesigning or retooling the bottom end. But the cylinder head and its poppet valves get thrown away. To replace the camshaft and valves, Beare has retained the cam drive belt and fitted an ultra short-stroke upper crankshaft complete with piston, which the belt drives at half engine speed just as it previously drove the cam. This piston drives up and down in a sleeve, past inlet exhaust ports set into the cylinder wall, very much like on a two-stroke: these are all exposed during both inlet and exhaust strokes. This being it's only function, the rotary valve is lightly loaded, reducing lubrication and sealing problems. During the compression and expansion strokes, the upper piston seals off both ports, leaving the pressure contained between the two pistons, with the lower one a conventional flat-top three-ring design, while the conical upper one (so shaped to aid gas flow during both inlet and exhaust cycles by guiding it towards the ports) has two rings - one compression, one oil. In the combustion phase, twin spark plugs provide ignition via the stock Ducati CDI and a pair of Harley coils - one per cylinder - and not only does the engine run on pure petrol (no need to add oil, because all required surfaces are positively lubricated, in spite of the application of two-stroke technology), it's also happy on low octane unleaded fuel. Obviously there are no valve seats to suffer from lack of lead, and Malcolm says the compression ratio can be increased significantly from the Ducati motor's 10.6:1 quite safely because of the lack of hotspots, without problems with detonation.
So now the claimed advantages of all this start to come to light - allowing a higher compression while still happy with low octane unleaded make this an efficient and cleaner engine. There are no poppet valves to float or bend. This is a much more cost-effective way of achieving this than expensively machining a set of closing rockers for all the valves in a cylinder head, quite apart from the unwanted inertia such a system still entails. But there are other, much more significant apparent spin-off benefits from the Beare design. First of these is fuel economy: Malcolm Beare claims his engine is 35% more economical at low revs/throttle openings than an equivalent conventional engine and 13% less thirsty at high rpm/full throttle, in spite of the doubled-up carbs. That should mean fewer hydrocarbon and CO2 emissions, because you're using less fuel to achieve the same performance. Ducati-based prototypes Beare discovered the six-stroke version produced the same torque as a four-stroke 1,000rpm lower down the scale, as well as producing exponentially more torque as revs rose. But in a commercial application, perhaps the most attractive benefit is the reduced number of moving parts, compared to a four-stroke design, so the six should be cheaper to make. Not as few as a two-stroke, but what you appear to be getting here is improved performance and torque, coupled with the inherent advantages of a four-stroke, on the cheap. Finally, as the upper two-stroke piston is driven at half engine speed, it should have twice the life of the lower four-stroke one.





Thermodynamic Advantages of six stroke engines




Referring to the graph, the intake begins at 0 degrees on the X-axis. The effect of the additional volume changes that the upper piston has on the volume of the engine is all positive from a thermodynamic point of view. If the engine were a normal 4 stroke the cylinder capacity would be 340cc. Of note - maximum volume at the end of the intake stroke occurs at 173 degrees instead of 180 degrees- the change in volume is 308cc which is less than a 4 stroke (340cc)- yet the total volume at the end of the intake stroke is 415cc as opposed to 375cc for a conventional stroke.
This means that the extra volume is best swept by gas velocities and not mechanical movement, and therefore mechanical input energy is less. Also, maximum volume is before bottom dead centre 173 deg. Consequently valve timing, if the same as a 4 stroke, is more radical and is of longer duration in relation to engine volume and hence volumetric efficiency is considerably improved.
The change in volume during the compression stroke is slightly greater than a 4 stroke after the ports are closed. The expansion stroke is much greater than a 4 stroke; both from T.D.C. to B.D.C. and from T.D.C. till the exhaust port is open. It is possible to leave the opening of the exhaust port later than in a 4 stroke because maximum volume is not reached until after B.D.C.-548 deg. Instead of 540 deg. Hence the 6 stroke system is better from a thermodynamic point of view because more energy is extracted from the expansion process.
During the critical combustion period the rate of change in volume in the 6 stroke is less than a 4 stroke. Minimum volume is not reached until after T.D.C., at 361 deg. This is because of the phasing of the upper piston. It is retarded in reaching its T.D.C. until 20 deg. after T. D.C. (380). This is much better from a thermodynamic view in that combustion occurs at a more constant volume; hence ignition timing is not as critical as in a 4 stroke. There is room in the combustion chamber for up to 4 spark plugs and two direct injectors if needed.
The change in volume during the exhaust stroke is less than a 4 stroke. This means that the negative pumping work is less than a 4 stroke. Extractive gas velocity is very important. Easily accomplished at T.D.C. with a fully open exhaust port
The design can cope with various runner diameters and lengths because the reed valves allow any positive pressure pulses to pass through and cancel any negative ones, as well as providing good secondary atomisation. Hence at low revs the long thin runners are in tune and at higher revs the shorter fatter ones take over with no need to shut down the long thin ones or visa versa as would be necessary with a normal 4 stroke. Swirl is in one direction at low revs and moves to tumble when the flows are in balance reverting to swirl in the other direction as the short fat ones predominate. A good spread of torque is achieved.

Construction Issues
The mass of the reciprocating parts in the head is about the same as a 4 stroke but the accelerations are much slower so energy absorption is less. The piston speed of the upper piston is about a quarter of the main piston; therefore its service life should be at least twice that of the main piston. There are no service adjustments necessary. There are no valves to drop or get hit if a timing belt snaps and the effective rev limit is only what the main piston will stand. The design has similarities to the Atkins and Miller designs in that the expansion stroke is larger than the intake stroke.
Per single cylinder the number of parts in the Beare design head is fifteen compared to a single overhead cam 4 stroke of approx. 40 to 50 parts. The design also allows the production of a single piece engine (i.e. head cast with the block) further reducing machining and therefore costs.
The tips of the reed valves are positioned close to the intake port windows, thus achieving a similar result to variable cam timing. At low throttle & revs the petals only partly open and keep gas velocity high .At full throttle & high revs they fully open to allow maximum flow.
The exhaust disk does not touch anything and is only subject to sub-atmospheric pressure, not gas flow; and therefore its service life is practically infinite. The exhaust valve is a piston port.
The simplest layout for car engines is the flat 4 or V4, with internal central chain drive to the heads. This layout allows access to 3 sides of each cylinder, with exhaust discs each end of the motor and reed valve blocks both sides of each cylinder.
For in-line layouts the drive chain or belt is at the end with a row of exhaust disks down one side and a row of intake disks or reed blocks down the other side. A right angle drive is taken off the drive chain with a very light internal drive chain to the disks, or a direct drive is taken off the drive chain with light right angle drive at each disk.

Graphical comparison of Four stroke and Six stroke engines

Advantages

(1) The Six stroke engine is fundamentally superior to the 4- stroke because the head is no longer parasitic but is a net contributor to, and an integral part of the power generation within the engine.
(2) The Six stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.
(3) The compression ratio can be increased because of the absence of hot spots.
(4) The rate of change in volume during the critical combustion period is less than in a 4 stroke.
(5) The absence of valves within the combustion chamber allows design freedom.
(6) A one-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.
(7) The valving is desmodromic
(8) There are no valves to drop or bounce.
(9) The rev limit is only what the bottom end can stand.
(10) Gas flow on intake increase of 20%.
(11) No possibility of engine damage if the timing belt slips or snaps
(12) The reed valves are so close to the intake ports that their tips become the virtual port opening. This achieves variable port area & variable engine demand valve timing. The tips open late & small amounts with low throttle settings & open early & fully at full throttle
(13) Increased torque and power output
(14) Better fuel economy
(15) Cleaner burning and reduced emissions
(16) Longer service intervals
(17) Reduced tooling cost
(18) Low cost of manufacturing





(19) Low machining cost due to absence of valves
(20) Higher compression ratio
(21) Small size
(22) Less number of parts compared to four stroke engine
(23) High torque at low rpm
(24) 35% more economic at low throttle and 13% more economic at high throttle when compared to OHC four stroke engine


Conclusion

From the above given data it can be easily understood the Beare technology or six stroke engines are the technology for the future. The project is well patented and is undergoing heavy research works. Any product takes time to establish itself in the market. Six stroke engines with all the desired qualities of a two stroke and four stroke engines will be hitting the market soon. From the above given data it is clear that six stroke engines are better compared to two stroke and four stroke engines. It is sure that six stroke engines will surely be the main stay of automobiles in the near future.

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07-01-2011, 09:37 PM
Post: #13
RE: six stroke engine
SIX STROKE ENGINE
Mohamed Suhail
S7 ME
02107027

.ppt  SIX STROKE ENGINE.ppt (Size: 951.5 KB / Downloads: 311)

Introduction
A six stroke engine derived its name from the fact that it is a mixture of two and four stroke engine.
This engine is a radical hybridization of two and four stroke engine that the top portion of two stroke engine and the bottom rather the middle section of a four stroke engine.
Principles of Two Stroke
Two stroke engines got its name from the fact that the required strokes are completed in one revolution.
In short there is one power stroke in one revolution.
Principles of Four Stroke
In the case of four stroke engines, the four strokes are completed in two revolutions.
There is a single power stroke in two revolutions.
Concept of Six Stroke
This technology is also known as Beare Technology.
This engine got its name due to its construction.
This engine is a radical hybridization of two and four stroke engines.
These types of engines have many advantages compared to OHC four stroke engines.
Construction
The drawbacks of poppet valves in conventional engines is overcome by means of a rotary valve application to four-stroke engine.
To replace the camshaft and valves, Beare has retained the cam drive belt and fitted an ultra short-stroke upper crankshaft complete with piston, which the belt drives at half engine speed just as it previously drove the cam.
Construction
It consist the basic components of a rotary disc induction two-stroke engine.
It is grafted on to a four-stroke, to produce the best of both worlds.
Working
Working
The top piston drives up and down in a sleeve, past inlet exhaust ports set into the cylinder wall, very much like on a two-stroke.
During the compression and expansion strokes, the upper piston seals off both ports.
In the combustion phase, twin spark plugs provide ignition via the stock Ducati CDI and a pair of Harley coils - one per cylinder. (sixstroke small.avi, sixstroke.avi)
Thermodynamic Advantages
The Six stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.
Construction Issues
The mass of the reciprocating parts in the head is about the same as a 4 stroke.
The piston speed of the upper piston is about a quarter of the main piston; therefore its service life should be at least twice that of the main piston.
Per single cylinder the number of parts in the Beare design head is fifteen compared to a single overhead cam 4 stroke of approx. 40 to 50 parts.
Torque-Angle diagram
There’s improved torque at lower revs, which will surely help in the stop-and-go nature of congested Indian traffic.
The six-stroke version produced the same torque as the four-stroke conventional motor 1000rpm lower down the rev scale, as well as making exponentially more torque as revs rose.
Advantages
The compression ratio can be increased because of the absence of hot spots.
The absence of valves within the combustion chamber allows design freedom.
One-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.
There are no valves to drop or bounce.
Advantages
Gas flow on intake increase of 20%.
Possibility of engine damage if the timing belt slips or snaps.
Increased torque and power output.
Better fuel economy.
Cleaner burning and reduced emissions.
Longer service intervals.
Reduced tooling cost.
Low cost of manufacturing.
Low machining cost due to absence of valves.
Higher compression ratio.
Conclusion
The industry trend away from cheaper two-stroke power in favor of costlier but cleaner four-stroke engines in both Europe, Japan and South East Asia makes a concept like the Beare six-stroke, which offers the best of both worlds, project a strong case towards volume manufacture.
150cc six-stroke Taiwanese single-cylinder bike from Yingang is ready to roll.
24-02-2011, 12:20 PM
Post: #14
RE: six stroke engine
PRESENTED BY:
SATYA PRAKASH


.doc  TPP_Pages 1-4.doc (Size: 576 KB / Downloads: 165)
6 STROKE ENGINE
THE SIX-STROKE ENGINE WITH EXTERNAL AND INTERNAL COMBUSTION AND DOUBLE FLOW CONCEPT

ABSTRACT
One of the most difficult challenges in engine technology today is the urgent need to increase engine thermal efficiency. This paper presents the six-stroke engine with external and internal combustion and double flow concept in the development of high-efficiency engines for the 21st century.
The majority of I.C.engines, operating on different cycles have one common feature, combustion occurring in the cylinder after each compression, resulting in gas expansion that acts directly on the piston and limited to 180 degrees of crankshaft angle.
According to its mechanical design, the six-stroke engine is similar to the I.C.engine. It differs due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: a combustion and an air heating chamber, both independent from the cylinder. Combustion, doesn’t occur within the cylinder but in the supplementary combustion chamber, doesn’t act immediately on the piston, and its duration is independent from the 180 degrees of crankshaft rotation that occurs during the expansion of the combustion gases.
The combustion chamber is totally enclosed within the air-heating chamber. By heat exchange through the glowing combustion chamber walls, air pressure in the heating chamber increases and generate power for an a supplementary work stroke.
Key words: Six stroke engine, external and internal combustion, heating chamber
1. INTRODUCTION
One of the most difficult challenges in engine technology today is the urgent need
to increase engine thermal efficiency. Thermal management strategies and the choice of fuels will play crucial roles in the development of high-efficiency engines for the 21st century.
However, it was during the 19th century that the fundamental principles governing the efficiency of internal combustion engines were first posited. In 1862, Alphonse Beau de Rochas published his theory regarding the ideal operating cycle of the internal combustion engine.
He stated that the conditions necessary for maximum efficiency were:
(1) Maximum cylinder volume with minimum cooling surface;
(2) Maximum rapidity of expansion;
(3) Maximum pressure of the ignited charge and
(4) Maximum ratio of expansion.
Beau de Rochas' engine theory was first applied by Nikolaus Otto in 1876 to a four-stroke engine of Otto's own design. The four-stroke combustion cycle later became known as the "Otto cycle".
In the Otto cycle, the piston descends on the intake stroke, during which the inlet valve is held open. The valves in the cylinder head are usually of the poppet type. The fresh fuel/air charge is inducted into the cylinder by the partial vacuum created by the descent of the piston. The piston then ascends on the compression stroke with both valves closed and the charge is ignited by an electric spark as the end of the stroke is approached. The power stroke follows, with both valves still closed and gas pressure acting on the piston crown because of the expansion of the burned charge. The exhaust stroke then completes the cycle with the ascending piston forcing the spent products of combustion past the open exhaust valve. The cycle then repeats itself.
Each Otto cycle thereby requires four strokes of the piston- intake, compression, power and exhaust- and two revolutions of the crankshaft.
The disadvantage of the four-stroke cycle is that only half as many power strokes are 2 completed per revolution of the crankshaft as in the two-stroke cycle and only half as much power would be expected from an engine of given size at a given operating speed. The four-stroke cycle, however, provides more positive scavenging and charging of the cylinders with less loss of fresh charge to the exhaust than the two-stroke cycle. Modern Otto cycle engines, such as the standard gasoline engine, deviate from the Beau de Rochas principles in many respects, based in large part upon practical considerations related to engine materials and the low-octane fuel used by the engine.
The six-stroke with external and internal combustion and double flow concept engine described in this monograph is designed to overcome many of the limitations inherent in the Otto cycle and bring the engine's operating cycle closer to Beau de Rochas' ideal efficiency conditions.
24-02-2011, 12:41 PM
Post: #15
RE: six stroke engine
sir,
pls send me the full report of seminar on 6 stroke engine and ppt if any.
your's sincerely
amj
21-03-2011, 07:11 PM
Post: #16
RE: six stroke engine
i need pdf file, for six stroke engine
06-04-2011, 04:15 PM
Post: #17
RE: six stroke engine
need full report on 6 stroke engine with pictures n animations with ppt for this topic.
16-04-2011, 01:19 PM
Post: #18
RE: six stroke engine
please sent me full details for this project
12-05-2011, 04:48 PM
Post: #19
RE: six stroke engine

.docx  munnu final touch up.docx (Size: 743.59 KB / Downloads: 184)
Introduction:
The term six stroke engine describes two different approaches in the internal combustion engine developed since the 1990s to improve its energy and environmental efficiency
Some designs capture the waste heat from the four stroke Otto cycle or Diesel cycle and use it to power an additional power and exhaust stroke of the piston. Designs either use steam or air as the working fluid for the additional power stroke. As well as extracting power, the additional stroke cools the engine and removes the need for a cooling system making the engine lighter and giving 40% increased efficiency over the Otto Cycle or Diesel Cycle. The pistons in a six stroke engine go up and down six times for each injection of fuel.
These six stroke engines have 2 power strokes, one fuel, one steam or air.
Consider the following:
A 10% efficiency improvement in vehicle performance would save over $10 billion and reduce emissions of carbon dioxide by 140 million tons per year. A 20% efficiency improvement could reduce foreign oil used today by 1/3. Consumers would save billions of dollars in fuel cost. Reduction in emissions would be in the hundreds of millions of tons per year, and dependency on foreign oil would be drastically reduced.
Working of a basic DIESEL engine:
The cycle starts with the intake stroke, which begins when the piston is near top dead center. The intake valve is opened, creating a passage from the exterior of the engine (generally through an air filter assembly), through the intake port in the cylinder head and into the cylinder itself. As the piston moves toward bottom dead center, a partial vacuum develops, causing air to enter the cylinder. In the case of a turbocharged engine, the air is rammed into the cylinder at higher than atmospheric pressure. As the piston passes through bottom dead center, the intake valve closes, sealing the cylinder.
The compression stroke begins as the piston passes through bottom dead center and starts upward. Compression will continue until the piston approaches top dead center. The energy required for the compression stroke comes from the momentum of a flywheel on the crankshaft as well as (in multi-cylinder engines) other pistons in their power stroke.
The power stroke occurs as the piston reaches top dead center at the end of the compression stroke. At this time, fuel injection occurs, resulting in combustion and the production of useful work.
The final stroke is the exhaust stroke, which begins as the piston approaches bottom dead center following ignition. The exhaust valve in the cylinder head is opened and as the piston starts upward, the spent combustion gases are forced out of the cylinder. Near top dead center the intake valve will start to open before the exhaust valve is fully closed, a condition referred to as valve overlap. Overlap produces a flow of cooling intake air over the exhaust valve, prolonging its life. Following the completion of the exhaust stroke the cycle will begin anew
Study about the basic engine
Our AEROZETA is made out of a working four stroke diesel engine.
Features of our basic engine:
These are the features of the engine from which the AEROZETA has been built.
Displacement 1000cc
No. of cylinders 3
Type of fuel used Diesel
Type of ignition system compression ignition
Type of injection direct injection
Placement of camshaft overhead camshaft
Firing order 1-2-3
Drive of crank and cam Belt driven
No. of teeth on the crank gear 20
No. of teeth on the cam gear 40
Study about the CAMSHAFT of the basic engine:
Camshaft in an engine is essential to operate the valves of the engine. When the lobe of the cam hits the tappet of the valve, it is forced downwards through the valve guide present in the head of the engine.
The most important elements of the cam shaft are the timing gear and the construction and placement of lobes.
Construction of the timing gear:
The timing gear is made based on the requirement of the necessary gear ratio between the crank shaft and the cam shaft. For a typical four stroke engine the velocity ratio is 1:2 as the rotation of the cam shaft should be half the time of rotation of the crank shaft.
Study of Design of the cam profile of the basic 4 stroke engine:
According to the study made by our team members,
There is a raise of 10mm over 43º degrees of the cam rotation.
Dwell at the max height up to 3º- 4º degrees of the cam rotation.
There is a fall after the dwell up to the cam’s min radius, which ends when the cam completes 90º degrees of rotation.
19-08-2011, 06:13 PM
Post: #20
RE: six stroke engine
I HAVE 2 MAKE SEMINAR TOPIC ON SIX STROK ENGINE PLZ HELP ME OUT
20-08-2011, 09:57 AM
Post: #21
RE: six stroke engine
To get more information about the topic "six stroke engine " please refer the link below


http://www.seminarprojectsThread-six-stroke-engine?pid=55069#pid55069

http://www.seminarprojectsThread-six-stroke-engine

http://www.seminarprojectsThread-six-stroke-engine?page=2

http://www.seminarprojectsThread-six-stroke-engine?page=3
25-08-2011, 04:06 PM
Post: #22
RE: six stroke engine
i need a ful report along with ppt. kindly forward me.
26-08-2011, 10:20 AM
Post: #23
RE: six stroke engine
To get more information about the topic "six stroke engine " please refer the link below


http://www.seminarprojectsThread-six-stroke-engine?pid=55069#pid55069

http://www.seminarprojectsThread-six-stroke-engine

http://www.seminarprojectsThread-six-stroke-engine?page=2

http://www.seminarprojectsThread-six-stroke-engine?page=3
18-04-2012, 01:04 PM
Post: #24
RE: six stroke engine
six stroke engine



.doc  SUDHEER.doc (Size: 1.33 MB / Downloads: 82)


INTRODUCTION

The six-stroke engine is a type of internal combustion engine based on the four-stroke engine, but with additional complexity intended to make it more efficient and reduce emissions. Two types of six-stroke engine have been developed since the 1990s:
In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke.[1] The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air. The currently notable designs in this class are the Crower six-stroke engine, invented by Bruce Crower of the U.S. ; the Bajulaz engine by the Bajulaz S.A. company of Switzerland; and the Velozeta Six-stroke engine built by the College of Engineering, at Trivandrum in India.
The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio. The currently notable designs in this class include two designs developed independently: the Beare Head engine, invented by Australian Malcolm Beare, and the German Charge pump, invented by Helmut Kottmann.
IC Engine:

I.C.Engine is a device which uses chemical energy of fuel & it is transformed into thermal energy by combustion to produce mechanical work.
Classification of I.C.Engine :-

1) According type of fuel used
a)Petrol b)Diesel

2) According to type of ignition
a)Spark ignition b) Compression ignition

3) According to number of cylinder
a)Single cylinder b) Multi cylinder Engine

4) According to arrangement of cylinder
a)Vertical engine 2) Horizontal engine 3) Radial engine

5) According to number of stroke
a) 2 stroke engine b) 4 stroke engine


Two Stroke Engine:

It is called 2 stroke engine because of one revolution of crank OR 2 stroke of piston.It Consists of piston ,crank, connecting rod,inlet & outlet Port’s & etc....
The Major disadvantage of 2 stroke engine is that both inlet & outlet valve opens simultaneously ,so that burnt fuel , fresh air & fuel mixture burnt simultaneously therefore fresh air & fuel may be exhausted without doing any work & also this may leads to high pollution & this what reason why “GOVT OF INDIA” Banned manufacturing of 2 stroke engine.

Two Stroke Engine
The two stroke engine employs both the crankcase and the cylinder to achieve all the elements of the Otto cycle in only two strokes of the piston.

Intake

The fuel/air mixture is first drawn into the crankcase by the vacuum that is created during the upward stroke of the piston. The illustrated engine features a poppet intake valve; however, many engines use a rotary value incorporated into the crankshaft.
25-04-2012, 12:27 PM
Post: #25
RE: six stroke engine
six stroke engine


.doc  TECHNICALPAPERON.doc (Size: 708 KB / Downloads: 54)


INTRODUCTION:

The majority of the actual internal combustion engines, operating on different cycles have one common feature, combustion occurring in the cylinder after each compression, resulting in gas expansion that acts directly on the piston (work) and limited to 180 degrees of crankshaft angle.


ANALYSIS OF SIX STROKE ENGINE:

Six-stroke engine is mainly due to the radical hybridization of two- and four-stroke technology. The six-stroke engine is supplemented with two chambers, which allow parallel function and results a full eight-event cycle: two four-event-each cycles, an external combustion cycle and an internal combustion cycle. In the internal combustion there is direct contact between air and the working fluid, whereas there is no direct contact between air and the working fluid in the external combustion process. Those events that affect the motion of the crankshaft are called dynamic events and those, which do not effect are called static events.


Internal combustion cycle

Direct contact between the air and the heating source.
I1. (Event 5) Re-compression of pure heated air in the combustion chamber (dynamic event)
I2. (Event 6) Fuel injection and combustion in closed combustion chamber, without direct action on the crankshaft (static event).
I3. (Event 7) Combustion gases expanding in the cylinder, work (dynamic event).
I4. (Event 8) Combustion gases exhaust (dynamic event).

CONSTRUCTIONAL DETAILS:

The sketches shows the cylinder head equipped with both chambers and four valves of which two are conventional (intake and exhaust). The two others are made of heavy-duty heat-resisting material. During the combustion and the air heating processes, the valves could open under the pressure within the chambers. To avoid this, a piston is installed on both valve shafts which compensate this pressure. Being a six-stroke cycle, the camshaft speed in one third of the crankshaft speed.


ADVANTAGES OF SIX STROKE OVER FOUR STROKE ENGINES:

The six stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake stroke, the compression stroke and the Six stroke engine is fundamentally superior to the four stroke because the head is no longer parasitic but is a net contributor to – and an integral part of – the power generation within exhaust stroke. The compression ration can be increased because of the absent of hot spots and the rate of change in volume during the critical combustion period is less than in a Four stroke.


CONCLUSION:

There is, at this day, no wonder solution for the replacement of the internal combustion engine. Only improvements of the current technology can help it progress within reasonable time and financial limits. The six-stroke engine fits perfectly into this view. It’s adoption by the automobile industry would have a tremendous impact on the environment and world economy, assuming up to 40% reduction in fuel consumption and 60% to 90% in polluting emissions, depending on the type of the fuel being used.
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Marked Categories : 6 stroke, six stroke hybrid engine, 6 stroke engine advantage, application of 6 stroke engine, an inroduction to six stroke engine, ppt for six stroke petrol, velozeta ppt, 6 stroke engine pdf, ppt on 6 stroke diesel by wiki, 6 stroke engine, six stroke engine animation, how to build a six stroke engine, engine 6 stroke, four stroke engine animation ppt, bruce crowers six stroke engine, mechanical seminar on six stroke engine zip, six stroke engine pdf, dis advantages of six stroke engine papers, dis advantages ofsix stroke engine papers, velozeta six stroke engine, 6 stroke engine ppt, six strock engine seminar report, six stroke engine, six stroke engine diagram,

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