WORKING PRINCIPLE OF A FOUR-STROKE CYCLE DIESEL ENGINE (ALONG WITH IT’S P-V AND VALVE TIMING DIAGRAM)

 WORKING PRINCIPLE OF A FOUR-STROKE CYCLE DIESEL ENGINE (ALONG WITH IT’S P-V AND VALVE TIMING DIAGRAM)

  

Four-stroke diesel engine: A four stroke diesel engine contains a fuel injector fuel pump, cylinder, cylinder head, inlet and exhaust valves, piston attached with piston range, connecting rods, crank shaft, corns, camshaft, etc. One cycle of a four stroke diesel engine is completed in four strokes of the piston or two revolution of the crank-shaft.

WORKING OF ENGINE:

1. Suction Stroke: The inlet(suction) valve opens, the exhaust valve or outlet valve remain close, only air is drawn into the cylinder as the piston moves from the  top dead center to the bottom dead center. This stroke ends as the piston approaches the bottom dead center (B.D.C).

2. Compression stroke: As the piston moves from bottom dead center to top dead center, the inlet valve closes, exhaust valve remains closed. The air trapped into the cylinder is compressed in the cylinder till the piston approaches the top dead center. The air temperature reaches about 800°C by compression. At the end of the compression stroke, the fuel is injected at very high pressure into the compressed hot air. The temperature of compressed hot air is sufficient to ignite the injected fuel. Thus, ignition keeps place into the cylinder.

3. Expansion Stroke: During expansion stroke, both valve remain closed. The piston at top dead center is pushed by expansion of burning gases. Actual work is obtained during this stroke due to the force obtained by high pressure burning gases. Therefore, this stroke is called power stroke or working stroke.

4. Exhaust Stroke: During this stroke the piston moves from the bottom dead center to the top dead center, exhaust valve opens and the inlet valve remain closed. Burnt gases of the previous stroke are expelled out from the cylinder of upward movement of the piston.