1.Intake Stroke
Inhale fresh air into the cylinder of the diesel generator set to provide the air needed by the diesel generator.

2. Compression Stroke
The intake and exhaust valves of the diesel generator set are closed, the piston moves up, the gas in the cylinder is compressed rapidly, the air pressure rises, and the temperature rises at the same time. When it reaches the self-ignition temperature of diesel, the diesel will burn and expand by itself.
Effect:
①Increase the temperature of the air to prepare for the self-ignition of the fuel
②Create conditions for gas expansion to do work
③The spontaneous combustion temperature of diesel is 543~563K

3.Combustion Expansion Stroke
The intake and exhaust valves are closed, the fuel in the cylinder is rapidly burned and expanded, and the gas pressure rises sharply, pushing the piston to move from top dead center to bottom dead center.
Pressure rise ratio: the ratio of combustion pressure to compression end pressure

4.Exhaust Stroke
The exhaust valve opens early and closes late: Exhaust resistance, such as a muffler, makes the exhaust valve open in advance to reduce the boost of the piston exhaust, and the piston mainly relies on inertia when completing the exhaust process.

A diesel engine in which the piston takes four strokes to complete a working cycle is called a four-stroke diesel engine.