The piston is a reciprocating mechanism in a cylinder block of an automobile engine. The basic structure of a piston can be divided into a top, a head, and a skirt. The top of the piston is the main part of the combustion chamber, and its shape depends on the type of combustion chamber selected. Gasoline engines mostly use flat top pistons, which has the advantage of a small heat absorption area. There are often various pits on the top of diesel pistons, and their specific shapes, locations and sizes must be compatible with the requirements for the formation and combustion of diesel mixtures.
Since the piston of the internal combustion engine works under high temperature, high pressure and high load conditions, the requirements for the piston are relatively high, so the classification of the piston of the internal combustion engine is mainly discussed. 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 combination piston.
3. According to the manufacturing process of piston blank, it can be divided into gravity casting piston, squeeze casting piston, and forging piston.
4. According to the working condition of the piston, it can be divided into two categories: non-supercharged piston and supercharged piston.
5. According to the purpose of the piston, it can be divided into car piston, truck piston, motorcycle piston, marine piston, tank piston, tractor piston, lawnmower piston and so on.
1. It must have sufficient strength, stiffness, small mass and light weight to ensure the minimum inertia force.
2. Good thermal conductivity, high temperature resistance, high pressure resistance, corrosion resistance, sufficient heat dissipation ability, and small heating area
3. There should be a small friction coefficient between the piston and the piston wall.
4. When the temperature changes, the size and shape change should be small, and the minimum gap between the cylinder and the cylinder wall should be maintained.
5. The coefficient of thermal expansion is small, the specific gravity is small, and it has good friction reduction and thermal strength.