Many of us may know about two stroke or four stroke engine.Those who are from mechanical or automobile field must have to familiar with this term.Actually two stroke or four stroke is the cycle of any reciprocating engine.When only two stroke required to complete the reciprocating engine cycle then that engine is known as two stroke engine,and when four stroke required to complete the cycle then it is known as four stroke engine.
In four stroke engine the work is obtained only during one stroke out of these for a single cylinder engine or for every cylinder individually for multi cylinder engine.If you have any automobile vehicle or machine,then you better know the above terms.But ever you know,which are these strokes and how it perform? Interested to go deep in topic? Read below description.
This is first stroke of your engine.During this stroke the piston is moved downward from Top Dead Centre by means of crankshaft which is rotate by electric motor.This movement increases the size of combustion space thereby reducing the pressure inside the cylinder,as the result,the higher pressure of the outside atmosphere forces the air into combustion space through suction valve.The exhaust valve remain closed in this stroke.
A carburettor is put in the passage of incoming air which supplies a controlled quantity of fuel to this air.This air-fuel mixture thus comes in engine cylinder.
This is second stroke of your engine.The air-fuel mixture is compressed during this upward stroke.The compression,forces the fuel into closer combination with air.Heat is produced due to compression aids the combustion of fuel.Just a little before the end of compression stroke the mixture is ignited by a spark produced by spark plug.During this stroke suction and exhaust valve remain closed.
This is third stroke of your engine.You may call it as Expansion Stroke also.The air-fuel mixture which burns at the end of compression stroke expands due to heat of combustion.This expansion of burnt air-fuel mixture exerts pressure in the cylinder and on the piston,and under this impulse the piston moves downward thus doing useful work.Suction and exhaust valve remain closed during this stroke.
This is last stroke of your engine.During this stroke the suction valve remain closed while the exhaust valve opens.The greater part of burnt gases escape because of their own expansion.The upward movement of piston pushes the remaining gases out of the open exhaust valve.Thus complete the exhaust stroke and one cycle of engine.
Number of cycles are depend upon the rotation per minute of your engine.Higher the R.P.M.,higher the work done carried out by engine.I hope,this information will better help you to understand the working of your four stroke engine.
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