Basic knowledge about automobile engines

Engines come in various structural forms, and their specific structures vary widely. However, most of the engines currently used in automobiles are reciprocating piston internal combustion engines. A modern automobile engine is a complex machine composed of many mechanisms and systems. Because the basic working principles are the same, their basic structures are also similar. Today, the most widely used are reciprocating piston engines that use gasoline and diesel as fuel, namely gasoline engines and diesel engines.

Gasoline engines usually consist of two major systems: a crank connecting rod mechanism and a gas distribution system, and five major systems: fuel supply system, lubrication system, cooling system, ignition system, and starting system; a diesel engine usually consists of a crank connecting rod mechanism and a gas distribution system. The mechanism is composed of four major systems: fuel supply system, lubrication system, and cooling system. The structures of gasoline engines and diesel engines are shown in Figure 1.

Figure 1.1.1 Automobile engine

1.1.1 Basic structure of the engine

(1) Crank connecting rod mechanism

< p>The crank connecting rod mechanism is composed of three parts: the engine block, the piston connecting rod group and the crankshaft flywheel group. Its function is to convert the heat energy generated by fuel combustion through the linear reciprocating motion of the piston into the rotational motion of the crankshaft and output it to the outside through the flywheel. power. The engine block group is the installation basis for various engine mechanisms, systems and some other components. It is also the assembly base for the crank connecting rod mechanism, valve train, fuel supply system, cooling system and lubrication system.

(2) Valve train

The valve train consists of a valve group and a valve transmission group. Its main parts include intake valves, exhaust valves, valve spring lifters, camshafts and timing gears. Its function is to regularly open and close the intake and exhaust valves of each cylinder according to the engine's working cycle and ignition sequence, fill the cylinder with fresh gas in a timely manner, and discharge the exhaust gas generated by combustion in a timely manner.