Valve Timing Diagram of Diesel Engine

Valve Timing Diagram for a Four Stroke Cycle Diesel Engine - The diesel engines are also known as compression ignition engines. The valve timing diagram for a four stroke cycle diesel engine is shown in Figure below:

The following particulars are important for a four stroke cycle diesel engine regarding valve timing diagram:

(a) The inlet valve opens at 10° — 20° before TDC and closes at 25° — 40° after BDC.

(b) The fuel valve opens at 10° — 15° before TDC and closes at 15°— 20° after TDC.

(c) The compression starts at 25° — 40° after BDC and ends at 10°— 15° before TDC.

(d) The expansion starts at 10° — 15° after TDC and ends at 30° — 50° before BDC.

(e) The exhaust valve opens at 30° — 50° before BDC and closes at 10° —15° after TDC.

Note: In diesel engines, the fuel is injected in the form of very fine spray into the engine cylinder, which gets ignited due to high temperature of the compressed air.