The engine is a complex machine composed of many mechanisms and systems. Whether it is a gasoline engine or a diesel engine; whether it is a four-stroke engine or a two-stroke engine; whether it is a single-cylinder engine or a multi-cylinder engine. In order to complete the energy conversion, realize the working cycle, and ensure the continuous normal work for a long time, we must have the following institutions and systems. The gasoline engine is composed of two major institutions and five major systems, that is, the crank connecting rod mechanism, gas distribution mechanism, fuel supply system, lubrication system, cooling system, ignition system and starting system; the diesel engine is composed of the above two major institutions and four major systems. That is, it is composed of a crank connecting rod mechanism, a gas distribution mechanism, a fuel supply system, a lubrication system, a cooling system and a starting system. The diesel engine is compression-ignited and does not require an ignition system.
The engine is a machine that converts a certain type of energy into mechanical energy. Its function is to convert the chemical energy of liquid or gas combustion into heat energy after combustion, and then convert the heat energy into mechanical energy through expansion and output power. The engine is a complex machine composed of many structures and systems. Its structural types are diverse, but because the basic working principle is the same, the basic structure is similar. The overall structure of the engine is shown below.