The force acting on the piston ring is the gas pressure, the ring's own elastic force, the inertia force of the ring reciprocating motion, the friction between the ring and the cylinder and the ring groove. Due to the action of these forces, the ring will produce axial motion, radial motion, rotary motion and other basic motions.

In addition, due to its movement characteristics, accompanied by irregular movement, the piston ring inevitably appears suspension and axial vibration, radial irregular movement and vibration, twisting movement caused by axial irregular movement. These irregular movements often prevent the piston ring from functioning. When designing the piston ring, it is necessary to give full play to the favorable movement and control the unfavorable side.

Thermal conductivity

The high heat generated by combustion is transmitted to the cylinder wall through the piston ring, so it can play the role of cooling the piston. The heat dissipated through the piston ring to the cylinder wall can generally reach 30 to 40% of the heat absorbed by the top of the piston.

Air tightness

The first function of the piston ring is to maintain the seal between the piston and the cylinder wall, controlling air leakage to a minimum. This role is mainly borne by the gas ring, that is, under any operating conditions of the engine, the leakage of compressed air and gas should be controlled to a minimum to improve thermal efficiency; Prevent the nip between cylinder and piston or cylinder and ring caused by air leakage; Prevent the deterioration of lubricating oil caused by failure.

Oil control

The second function of the piston ring is to appropriately scrape off the oil attached to the cylinder wall and maintain normal fuel consumption. When the oil supply is too much, it will be sucked into the combustion chamber, increasing the fuel consumption, and because of the carbon deposition generated by combustion, it has a very bad impact on the engine performance.

supportability

Because the piston is slightly smaller than the inner diameter of the cylinder, if there is no piston ring, the piston is unstable in the cylinder and it is impossible to move freely. At the same time, the ring also prevents the piston from contacting the cylinder directly and plays a supporting role. Therefore, the piston ring moves up and down in the cylinder, and its sliding surface is borne by the ring.

(Text from the network, infringement please contact delete)