A 6 stroke engine is an improvement over the current 4
stroke engine used in automobiles. Consider a 4 stroke engine with 4
strokes (intake, compression, power and exhaust); a 6 stroke engine provides an extra power and exhaust strokes. The heat
of combustion which is leftover after the exhaust stroke (4th
stroke) is used to create an additional expansion stroke. Air or water can be
used as the fuel for the 5th stroke.
Working Principle of
6 Stroke Engines:
The principle of 6 stroke engines is to capture the waste
heat from the 4 stroke Otto cycle or Diesel cycle and utilizing the waste heat
to generate an additional power stroke and exhaust stroke. Air or water is used
as the working fluid for the additional power stroke.
Design of 6 stroke
engines:
The design is pretty much similar to a conventional 4 stroke
internal combustion engine. The piston moves up and down the combustion
chamber. Apart from the existing intake and exhaust valves, there are
additional air suction valve and air exhaust valve for the 5th and 6th
strokes respectively.
WORKING OF 6
STROKE ENGINES:
1st Stroke
(Intake stroke):
Consider a 6 stroke engine with Otto cycle; the intake valve
opens and air-fuel mixture is sucked into the combustion chamber due to the
piston movement from top dead centre (TDC) to bottom dead centre (BDC). The movement
of piston from TDC to BDC creates negative pressure in the cylinder, which
sucks in more air-fuel mixture.
2nd Stroke
(Compression stroke):
In the compression stroke, all 4 valves will remain closed.
The air-fuel mixture is trapped inside the combustion chamber. Now the piston
starts moving from BDC to TDC and compressed the air-fuel mixture inside the
combustion chamber.
3rd Stroke
(Power stroke):
Just before the piston reaches the TDC in the combustion
chamber, a spark plug ignites the compressed air-fuel mixture. This generates a
lot of heat and the piston is forced to move down from TDC to BDC. The
expansion of gases releases energy (horsepower) which is used to run the
vehicle. All 4 valves remain closed during this operation.
4th Stroke
(Exhaust stroke):
The exhaust valve opens and the movement of piston from BDC
to TDC pushes the exhaust gases out through the exhaust valve. Now we are quite
familiar with these 4 strokes in a conventional 4 stroke engine. We also are
aware of the fact that there is some leftover heat in the combustion chamber
after the exhaust stroke. The leftover heat is used in the 5th
stroke.
5th Stroke
(Air Suction):
Fresh air from the atmosphere is sucked in through the air
suction valve. The high temperature inside the combustion chamber heats the
fresh air and this leads to expansion of air which forces the piston to move
down from TDC to BDC to provide an additional power stroke. The air can also be
pre-heated before being sent into the combustion chamber. Pre-heated air will
result in better expansion.
6th Stroke
(Air Exhaust):
The air exhaust valve opens and as the piston moves up from
BDC to TDC, the expanded air is sent out through the exhaust. This provides
better gas scavenging.
In some cases, even water can be injected inside the
combustion chamber after 4th stroke. The water is converted into
steam due to heat and creates an auxiliary power stroke.
Advantages of 6
Stroke Engines:
·
Higher fuel economy up to 40%
·
No cooling system required as heat is carried
away during 5th and 6th stroke
·
Significant reduction in emissions
·
Two power strokes for 6 strokes
·
Can run on multiple fuels, including LPG
Types of 6 Stroke Engines:
There are several designs of 6 stroke engines that work on different concepts to generate an additional power stroke and exhaust stroke.
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ReplyDeletereading this article made me understand 6s cycle in its simplicity
ReplyDeleteThanks to provide this such nice information. you have done great work. Bp Auto Spares India
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