TWO STROKE SPARK IGNITION ENGINES (SI ENGINES)

TWO STROKE SPARK IGNITION ENGINES

(SI ENGINES)

Four working processes (additional one) done in 

two strokes and Ports (Inlet, Transfer and Exhaust ports) 

are there in 2 stroke engines.

• Upward Stroke:
• Suction  and Compression: Piston moves from BDC to TDC.                
• Downward Stroke:
• Power, Exhaust and Crankcase Compression: Piston moves from TDC to BDC.    

     

• Upward Stroke:
• Suction  and Compression:
• Inlet port opened and exhaust & transfer ports are closed.
• Downward Stroke:
• Power, Exhaust and Crankcase Compression:
• Inlet port closed and exhaust and transfer ports are opened.      

• Upward Stroke:
• Suction: Air-fuel (Petrol/gasoline) mixture entry into the    engine crankcase side due to increase of crankcase volume by piston movement from BDC to TDC.

• Compression: Due to decrease of cylinder volume in combustion chamber side by piston movement, the mixture gets high pressure and temperature and its ready to combustion. At the end of compression, the spark ignited from spark plug and combustion takes place.

• Downward Stroke:
• Power: After combustion, the power gets (mechanical energy), due to power the piston moves from TDC to BDC.

• Exhaust: During the movement of piston towards down, the exhaust port open and leaves the exhaust gases through it from engine cylinder to atmosphere.

• Crankcase Compression: During downward stroke, the piston compress the mixture in crankcase side and its transfer through transfer port and enter into combustion side for power next cycle.

                

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