A Seminar

On

SIX STROKE ENGINE

By

Mr.Saurabh Abhay Chaudhari

Guided By

DEPARTMENT OF MECHANICAL ENGINEERING

ALL INDIA SHRI SHIVAJI MEMORIAL SOCIETY’S COLLEGE OF

ENGINEERING, PUNE – 411001.

2015-2016

ALL INDIA SHRI SHIVAJI MEMORIAL SOCIETY’S COLLEGE OF

ENGINEERING, PUNE – 411001

DEPARTMENT OF MECHANICAL ENGINEERING

This is to certify that SAURABH ABHAY CHAUDHARI has successfully carried out the

seminar on “SIX STROKE ENGINE” during the academic year 2015-2016, for the partial

fulfilment for the award of degree of Mechanical Engineering (Sandwich) of the Savitribai Phule

Pune University.

ABSTRACT

The quest for an engine 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 conducted

on this topic nowadays and already six types of six stroke engines were discovered

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 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. 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.

In the present article a brief history and types of six stroke engine were dealt and the

advantages of the six stroke engine over other conventional engines were dealt using various

performance curves.

INTRODUCTION

The term six stroke engine describes two different approaches in the internal combustion engine,

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

Velozeta’s Six-stroke engine built by the students of an engineering college Trivendrum.

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.

HISTORY OF SIX STROKE ENGINES

Its concept was developed in 1880s.However the rapid research commenced only after

1990s. 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 Velozeta’s Six-stroke engine built by the students

of an engineering college Trivendrum.

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.

First Category:-

The engines coming under this category are:

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

Griffin’s engine and they licensed the Griffin patents also

marketed the engine under the name ‘Kilmarnock’. They used

this engine mainly for electric power generation.

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

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

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.

Charge pump 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, pre-

compression, gas transfer, compression, ignition and ejection.

DISCUSSION ON THEORY

According to the theory more torque is derived if the upper piston drive is advanced in relation

to the main crank. This would be so if all other factors remain constant. Advancing the upper

piston drive has detrimental effects on valve timing, combustion chamber volume and rate of

change in volume during the combustion period and total engine volume.

1. Valve Timing: The effect is to open the exhaust port earlier, reduce the amount of valve

overlap and close the intake port earlier. Opening the exhaust port earlier means that the

expansion stroke is effectively shortened and less energy is extracted. Reducing the

amount of overlap does not allow enough time for intake to clear the combustion

chamber and the exhaust extraction effect is reduced. The earlier intake port closing

reduces charge filling and volumetric efficiency.

2. Combustion chamber volume: It is effectively increased thus lowering compression

ratio. The rate of acceleration of expansion is faster in the earlier periods, contrary to

the ideal of a constant volume during combustion.

3. Total Engine Volume: The effect is to reduce change in volume during intake and

compression and increase expansion and exhaust, thus reducing volumetric efficiency

of intake.

If we do advance the timing we would have to compensate in the design of the

engine by

1) Reducing combustion chamber volume.

2) Raising exhaust port lower lip to provide later exhaust opening.

3) Lowering intake port lower lip to provide later intake closing.

4) Altering disc timing to allow exhaust port closing.

ENGINE PARTS MODIFIED

1) Cam shaft / Crank shaft 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. An extra cam is provided for the water injector as well.

3) Valve Timing:

The valve timing of the

four stroke Honda engine

has been changed. The inlet

valve opening (IVO) is 10°

at TDC, same as that of the

four stroke Honda activa

engine. Inlet valve Closes

(IVC) at 20° after BDC,

same as that of the four

stroke engine. Exhaust

valve opens (EVO) 10° 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 is sucked into the cylinder

through the secondary air induction line. The reed valve opens to permit the air flow.

During the sixth stroke, the air is removed through the exhaust manifold .The reed valve

opens and the reed valve closes during this stroke. The inlet valve remains closed

during these strokes.

5) Cam Follower Modification:

Cam follower modification the bottom shape of

regular follower has the flat pattern, which is

suitable with the normal camshaft for four stroke

engine. The shape of the follower must be roller

or spherical shape. In this case a spherical shape

is chosen as its contact area is less.

6) Water Injection System:

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 pump or by the

progressive cavity pump.

1. Water Metering Pump: A positive displacement pump capable of driving a

fixed quantity of water into the cylinder at regular intervals, independent of the

back pressure applied.

2. 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.

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. The working of the engine is as

follows. Also the detailed label of engine parts in the figures is given below.

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 ( 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.

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.

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.

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.

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.

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. 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.

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.

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.

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%, whereas the thermal efficiency of six stroke engine lies between 40

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 ratios 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.

Main advantages of the six-stroke engine:

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.

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.

3. 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 engine’s own

characteristics which will help to considerably lower HC, CO and NOx emissions.

Furthermore, its 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. Multifuel:

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. It’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.

Limitations of A 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.

Conclusion

Six stroke engine has many advantages like high thermal efficiency, low fuel consumption, high

break mean effective pressure, and 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.

References

1) Patent Number: 252642 Publishing Date: 1st June 2015.

2) 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.

3) 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

4) Publication number: US8291872 B2, Published June 2012.

5) International Journal of Advance Engineering and Research Development, Volume 2,

Issue 6, June-2015.

6) Speculative analysis for design considerations in six stroke IC Engine,

www.conferenceworld.in, Published-10th April 2016, ICRTESM-16.

7) Conklin a 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).