The advantages of diesel engine are high torque and good economic performance. Each working cycle of diesel engine also experiences four strokes: intake, compression, work and exhaust. But because the fuel used in diesel engine is diesel, its viscosity is higher than that of gasoline, which is not easy to evaporate, and its spontaneous combustion temperature is lower than that of gasoline, so the formation of combustible mixture and ignition mode are different from those of gasoline engine. The main difference is that the mixture in the diesel engine cylinder is compression ignition, not ignition. When the diesel engine is working, air enters the cylinder. When the air in the cylinder is compressed to the end point, the temperature can reach 500-700 ℃, and the pressure can reach 40-50 atmospheres. When the piston is close to TDC, the high-pressure pump on the engine injects diesel into the cylinder at high pressure. The diesel oil forms fine oil particles and mixes with high-pressure and high-temperature air. The diesel mixture burns by itself, expands violently and generates explosive force to push the piston down to work. At this time, the temperature can reach 1900-2000 ℃, and the pressure can reach 60-100 atmospheres. The torque generated is very large, so the diesel engine generates diesel Motivation is widely used in large diesel vehicles.