Since the pistons of internal combustion engines work under the conditions of high temperature, high pressure and high load, the requirements for the pistons are relatively high, so this article mainly discusses the classification of pistons of internal combustion engines.
1. According to the fuel used, it can be divided into gasoline engine piston, diesel engine piston and natural gas piston.
2. According to the material of the piston, it can be divided into cast iron piston, steel piston, aluminum alloy piston and combined piston.
3. According to the manufacturing process of the piston blank, it can be divided into gravity casting piston, squeeze casting piston and forging piston.
4. According to the working conditions of the piston, it can be divided into two categories: non-pressurized piston and pressurized piston.
5. According to the purpose of the piston, it can be divided into automobile piston, truck piston, motorcycle piston, marine piston, tank piston, tractor piston, lawn mower piston, etc.

The main function of the piston is to withstand the combustion pressure in the cylinder and transmit this force to the crankshaft through the piston pin and connecting rod. Furthermore, the piston, cylinder head and cylinder walls together form a combustion chamber.

The piston is a component of the combustion chamber, so it is often made in different shapes. The piston of the gasoline engine adopts a flat top or a concave top at most, which makes the combustion chamber compact, the heat dissipation area is small, and the manufacturing process is simple. Top pistons are commonly used in two-stroke gasoline engines. Diesel engine piston crowns are often made into various pits.

The piston head is the part above the piston pin seat, and the piston ring is installed on the piston head to prevent high temperature and high pressure gas from entering the crankcase and preventing oil from entering the combustion chamber. Most of the heat absorbed by the top of the piston is also transferred through the piston head to the cylinder and then away through the cooling medium.