2. Content
▪ What is a six stroke engine???
▪ Different approaches in a six stroke engine.
▪ Working principle of a six stroke engine.
▪ Engine Modifications.
i. Fuel Tank.
ii. Material.
iii. Cam Shaft & Valve timing.
iv. Water Injector.
▪ Advantages.
▪ Drawbacks.
▪ Conclusions.
▪ References.
3. What Is A Six Stroke Engine???
▪ The SIX-STROKE engine is a type of internal combustion engine based on
conventional four stroke engines.
▪ It has some additional features to make it more energy efficient and to reduce
emissions.
▪ A six stroke engine has two power strokes as compared to one power stroke of
the conventional four stroke engine.
4. Working Principle
▪ A six stroke engine describes a number of different approaches in the internal
combustion engine to capture the waste heat from the four stroke Otto 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.
▪ In case of a 2 stroke or 4 stroke engine the cylinder head and cylinder walls
merely act as a parasite by absorbing useful heat energy. In case of a six stroke
engine this no longer happens because the cylinder head and cylinder walls act
as an integral part of the power generation cycle.
5.
6. First Stroke
▪ Piston Moves from TDC to BDC and
creates vacuum pressure in the cylinder.
Due to the vacuum pressure air fuel is
sucked into the cylinder via the inlet port.
Second Stroke
▪ Piston Moves from BDC to TDC and
compresses the mixture.
7. Third Stroke
▪ At the end of the compression stroke
the fuel is ignited and burnt. The
pressure and temperature in the
cylinder increases rapidly. The
increased temperature pushes the
piston downward.
Forth Stroke
▪ The burnt product is pushed out from
the exhaust valve by scavenging.
8. Fifth Stroke
▪ At the end of the exhaust stroke the
cylinder temperature becomes around
1000-1200 C.
▪ At this stage atomized water expansion
is injected into the cylinder.
▪ The water turns into vapor increasing its
volume around 1600 times. This causes
the piston to move from TDC to BDC.
Sixth Stroke
▪ The Piston is again reciprocated back
from BDC to TDC.
9. 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.
For this purpose the engine components are manufactured using thermal resistant alloys like:
i. Silicon Carbide.
ii. Zirconia.
iii. Alumina-Tungsten Alloys.
10. Engine Modifications
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
revolution of the crankshaft.
▪ The camshaft of 6-stroke engine contains three cams.
i. Intake Cam.
ii. Exhaust Cam.
iii. Water Injector Cam.
11. Engine Modifications
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.
12. Analysis and Testing
1. Pressure And Volume Diagram:
▪ 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.
13. Analysis and Testing
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. Analysis and Testing
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. 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.
16. Limitations Of Six Stroke Engine
1. Early engine starting problems.
2. Running Problems in cold regions.
3. Requirement Of neutral water.
4. Engine size increases due to additional components.
5. Higher manufacturing costs.
17. 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 eliminated by using heater or glow plug and coupling a dc
motor as prime mover to the engine. Nowadays research and experiments are
going on to modify the engine further and to make it suitable for practical purpose.
18. References
▪ Patent Number: 252642 Publishing Date: 1st June 2015.
▪ 15th International Conference on Applied Mechanics and Mechanical Engineering, 29-31 May,
2012,report by M. M. Gasim, L. G. Chui and K. A. Bin Anwar.
▪ http://www.ijedr.org/papers/IJEDR1402179.pdf (International Journal of engineering development
and research) ISSN:2321-9939, Vol.2, Issue 2, pp.2409-2416, June 2014. Unique Identification
Number IJEDR1402179
▪ Publication number:US8291872 B2, Published June 2012.
▪ International Journal of Advance Engineering and Research Development,Volume 2,Issue
6,June-2015.
▪ Speculative analysis for design considerations in six stroke IC Engine, www.conferenceworld.in,
Published-10th April 2016, ICRTESM-16.
▪ Conklina J. C. and Szybist J. P., "A Highly Efficient Six-Stroke Internal Combustion Engine Cycle
with Water Injection for In-Cylinder Exhaust Heat Recovery", Energy, Volume 35, Issue 4, pp.
1658-1664 (2010).
