Six stroke engine

This presentation was created during a short seminar that was the part of B.Tech Program

1. GURKRISHAN SINGH 1508089 D4 ME A2 SIX STROKE ENGINES

2. 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. A six stroke engine has two power strokes as compared to one power stroke of the conventional four stroke engine . The concept of six stroke engine was developed in mid 20th century when pollution due to the conventional IC engine increased .

3. BRUSH CROWER TYPE SIX STROKE ENGINE The six stroke engine “Using water” was developed By Brush Crower in 2006 and he patented his product at the end of 2007. The engine captures heat, which is lost from conventional four stroke cycle and additional strokes use it to produce power by introducing water inside the super heated cylinder . The working principles of six stroke engine is based on the concept of four stroke engine but with some modification, another two strokes are added.

4. WORKING SUCTION STROKE The piston moves from top dead center to the Bottom dead center and creates vacuum pressure So the Air and fuel mixture is sucked in to the Cylinder .

5. COMPRESSION STROKE: The piston moves from Bottom dead center to top dead center and compresses the Mixture . The mixture is compressed To high temperature and pressure . POWER STROKE : At the end of compression stroke the fuel is ignited and burnt . The pressure inside the cylinder increases rapidly and it pusses the piston down and the power is transmitted from piston to wheel.

6. EXHAUST STROKE: The Burnt product is pushed through the exhaust valve by the upward movement of the piston . SECONDARY POWER STROKE: At the end of the exhaust stroke the cylinder Temperature becomes around 900-1000 C. At this stage water is injected by an Injector in the form of fine droplets. The water turns into Vapour increasing volume around 1600 times when it comes in contact with the superheated cylinder .

7. The water turns into vapour increasing volume around 1600 times when it comes in contact with the superheated cylinder. SECONDARY EXHAUST STROKE: In this stroke the water vapour is exhausted by the upward motion of the piston.

8. Valve timing diagram of 6-stroke engine IVO: Inlet Valve open EVO: Exhaust Valve Open IVC: Inlet Valve Close EVC: Exhaust Valve Close WC : Water Injection

9. Thermodynamic analysis of power strokes: Fuel power stroke:

10. Water injection 2 ND power stroke: In order to determine the engine parameters, in 2011 HONDA motors conducted the first simulation of the six stroke engine by using a modified Honda GC190 engine.

11. SIMULATION RESULTS POWER AND TORQUE V/S ENGINE SPEED

12. THERMODYNAMIC ANALYSIS AND COMPARISION WITH 4-STROKE ENGINE 1.Pressure And Volume Diagram :

13. ▪ Work obtained by six stroke is the sum of the both combustion work and vaporization work. So that the break mean effective pressure will increase . 2. Fuel Flow Rate: ▪ Amount of fuel supplied to the engine per unit time is the fuel flow rate. ▪ As the diagram shows the fuel flow rate of 6-stroke engine is 50% lesser than the conventional 4-stroke engine.

14. 3.Thermal Efficiency: ▪ The thermal efficiency of the engine is the power produced by the engine to the power available from fuel. ▪ The thermal efficiency of the four stroke engine lies between 20-30%, where as ▪ The thermal efficiency of six stroke engine lies between 40-50%.

15. BRAKE SPECIFIC FUEL CONSUMPTION: It is the ratio of fuel consumption per second to the brake power. As from the diagram the brake specific fuel consumption of 6-stroke engine is much lower than the conventional six stroke engine.

16. Engine Modifications 1.Fuel Tank: The Fuel tank in a six stroke engine has to be divided into two parts. One part will contain fuel and other part will contain water. The water used should be distilled and pure . 2.Materials Used For Engine Components: The engine components are subjected to thermal stresses developed due to injection of water into the superheated cylinder. The rapid temperature changes can cause micro cracking or fracture of the engine components due to continuous compression and expansion.

17. For this purpose the engine components are manufactured using thermal resistant alloys like: I. Silicon Carbide. ii . Zirconia . iii . Alumina-Tungsten Alloys. 3.Cam Shaft Design: ▪In traditional four stroke engines the angular speed of the camshaft is half of the crankshaft. The Cam rotates ones for every two revolutions of the cam . ▪In six stroke engine the camshaft has been designed to turn one revolution for every three revolutionof the crankshaft.

18. ▪The camshaft of 6-stroke engine contains three cams. I. Intake Cam. ii . Exhaust Cam. iii . Water Injector Cam.

19. 4.Water Injector: ▪The water injection is done by the help of water injector which is operated by the cam. This thing can be done more effectively by the use of water metering. ▪Water metering pump is a positive displacement pump capable of driving a fixed quantity of water into the cylinder at regular intervals.

20. Progressive cavity pump: It is a screw pump positive displacement variant. In this the working fluid passes through series of discrete cavities as rotor is turned. The pump is to be synchronized with the output shaft of the engine with a reduction gear of 3:1 ratio.

21. Advantages Of Six Stroke Engine 1.Due to an additional power stroke efficiency of the engine increased. 2.Better scavenging and more extraction of work . 3.Reduction in fuel consumption by at least 40%. 4.No cooling system required like heat exchanger in case of Crower six stroke engine. 5.Reduction in pollutants like NOx, CO ,CO2,photochemical smog etc., up to 55%. 6.Increase in indicated thermal efficiency. 7.Minimize necessity of heat exchanger e.g. radiator.

22. Limitations Of Six Stroke Engine  Early engine starting problem: As the engine is not sufficiently hot at the starting the water injection stroke cannot be taken place. So a prime mover is used to run the engine for some cycle and after heating of the cylinder it is cut out.  Running problem in cold region: As the temperature in cold region is low there might be problem in case of water injection stroke as the cylinder temperature is low .  Requirement of neutral water: As the steam is generated in 2 nd power stroke, if the water is not neutralized it may react with the cylinder wall and with the piston top which results cavitation and distortion of the metal. It causes the uneven heat transfer between the water droplets and the cylinder wall which may decrease the performance of the engine. And it is difficult to carry neutral water all the times .

23. 4.Engine size increases due to additional components. 5.Higher manufacturing costs. Conclusion: Six stroke engine has many advantages like high thermal efficiency, low fuel consumption , high break mean effective pressure, low emission. However drawbacks like initial starting problem, availability of water are also associated. The starting problem can be Can be eliminated by using heater or glow plug and coupling a dc motor as prime mover to the engine. Now a days research and experiments are going on to modify the engine further and to make it for practical purpose.

24. BEARE HEAD SIX STROKE ENGINE Introduction:  Malcolm beare built an innovative hybrid design of the I C engine , by combining a two stroke with a four stroke engine.  The Beare Head is a new type of four stroke engine head design known as the “Beare Head ”.  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 ).

25. ABOUT ENGINE : 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.

26. FIGURE WISE EXPLANATION: 1. Fuel ignites with piston at the top dead center . 2. Rotary valve opens , allowing exhaust to escape. 3. Exhaust stroke begins when the piston is at bottom dead center. 4. Exhaust stroke ends, intake begins . Rotary valve cuts exhaust .intake of charge into cylinder due to Pressure difference. 5 . 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. 6. Top piston nearly closes complete inlet port and The Compression begins. 7. Combustion Chamber completely sealed and ready for the combustion. 8. 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 that 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.

27. Comparison Of Six Stroke Engine With Four Stroke Engine:

28. CONCLUSION: 1 . In a six stroke engine the energy absorption is less because of slower acceleration of reciprocating parts. 2 . It reduces the weight and complexity of the engines head by as much as 50%. Instead of using energy to drive the head. 3.Torque is increased by 35% and efficiency increased by the same. 4.Increased torque and power output.

29. Gallery UPPER CRANK WITH PISTON 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.

30. CYLINDER HEAD FROM BELOW CYLINDER HEAD UPPER VIEW

31. 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 .  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.

32. 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 .

33. Conclusion: 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 . 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 one piece . The bottom piston is a standard design and the Beare Head bolts directly onto the engine block replacing the overhead valves and standard head. 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.

34. 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 . Increased torque and power output. Better fuel economy and cleaner burning longer service intervals and considerably reduced tooling costs when compared with a conventional four stroke design .

35. References: 1. www.sixstroke.com 2. Excerpts from Beare technology. 3. High speed internal combustion engines by John B. Heywood. 4. http://www.jack-brabham-engines.com/ 5. http://www.autocarindia.com/new/Information.asp?id=1263 6. www.seminarsonly.com

36. THANKS