WORKING OF TWO STROKE CYCLE C.I Engine ( Diesel Engine )

The working of two stroke C.I Engine slightly differs from the S.I engine. Instead if sparkplug, the fuel injector is placed on the top of the cylinder.

First Stroke :

In the first stroke, the piston moves from BDC to TDC. When the piston is at BDC, partially compressed air from the crank case enters into cylinder through transfer port. Then the piston moves upward and further compresses the air into high pressure and temperature till the piston reaches TDC. At the end of the compressor stroke, The fuel injector injects the fuel in atomized form and ignited automatically by the compressed air.

During the upward movement of the piston, a slight vacuum will be produced at the crank case to suck the air from atmosphere.

Second Stroke :

When the fuel and air are ignited, it suddenly increases the pressure and temperature of the gas. Therefore, the gases will expand and it pushes the piston downward and producing the power stroke. During the expansion, some of the heat energy produced is converted into mechanical work.

During the downward stroke of the piston, first it uncovers the exhaust port and the burnt gases are sent out of the engine. At the same time, all the burnt gases are not exhausted. Therefore, scavenging takes place in the cylinder. (Scavenging process already defined in previous section).

At the time of downward movement of the piston, already entered air in the crankcase is partially compressed by the underside of the piston. The process is called crank case compression.

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