When the intake valve is opened and the exhaust valve is closed, the piston moves from the top dead center to the bottom dead center, the volume of the cylinder above the piston increases, resulting in a vacuum degree, and the pressure in the cylinder drops below the intake pressure. Under the action of vacuum suction, the gasoline atomized by the gasoline injection device is mixed with air to form combustible mixture, which is sucked into the cylinder through the air inlet and intake valve.

The intake valve and exhaust valve are closed, which compresses the combustible mixture in the cylinder, and the temperature and pressure of the mixture rise. Before the piston approaches the top dead center, the pressure of combustible mixture rises to 0.6 ~ 65438±0.2 MPa and the temperature can reach 330 ~ 430℃.

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The function of the automobile engine is to provide power for the automobile, which is the heart of the automobile and determines the power, economy, stability and environmental protection of the automobile. According to different power sources, automobile engines can be divided into diesel engine, gasoline engine, electric vehicle motor and hybrid power.

Common gasoline engines and diesel engines belong to reciprocating piston internal combustion engines, which convert the chemical energy of fuel into mechanical energy of piston movement and output power to the outside world. Gasoline engine has the advantages of high speed, low quality, low noise, easy start and low manufacturing cost. Diesel engine has high compression ratio and high thermal efficiency, and has better economic performance and emission performance than gasoline engine.

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