FOUR STROKE SPARK IGNITION ENGINES (SI ENGINES)

FOUR STROKE SPARK IGNITION ENGINES

(SI ENGINES)

Four working processes done in four individual strokes and 

Valves (Inlet and Exhaust valves) are there in 4 stroke engines.

• Suction -------------- Piston moves from TDC to BDC.
• Compression ------- Piston moves from BDC to TDC.
• Power --------------- Piston moves from TDC to BDC.
• Exhaust ------------- Piston moves from BDC to TDC.

• Suction----------: Inlet valve open and exhaust valve closed.
• Compression---: Inlet valve and exhaust valve both are closed.
• Power-----------: Inlet valve and exhaust valve both are closed.
• Exhaust---------: Exhaust valve open and inlet valve closed.

• Suction :Air-fuel (Petrol/gasoline) mixture entry into the engine due to increase of cylinder volume by piston movement.

• Compression: Due to decrease of cylinder volume by Piston movement, the mixture gets high pressure and temperature and ready to combustion. At the end of compression, the spark ignited and combustion takes place.

• Power: During power the piston moves from TDC to BDC. Its nothing but working stroke.

• Exhaust: During this process, the exhaust gases leaves from engine cylinder.

Composed by:  R.Satheesh, M.E., Asso Prof., email: rsatheeshemail@gmail.com.