How Car Parts Work: 6 stroke engine

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 (4^th stroke) is used to create an additional expansion stroke. Air or water can be used as the fuel for the 5^th 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 5^th and 6^th strokes respectively.

WORKING OF 6 STROKE ENGINES:

1^st 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.

2^nd 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.

3^rd 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.

4^th 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 5^th stroke.

5^th 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.

6^th 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 4^th 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 5^th and 6^th 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.

Types of 6 stroke engines

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