Figure 1. Cross-section of a cylinder in an internal combustion engine Located between the cylinder and the piston, piston rings are necessary components that allow the engine to operate efficiently. Piston rings have four major functions.

Function1.Compression gas sealing

Piston rings maintain gas compression between the piston and the cylinder wall.

Piston rings seal the cylinder so that combustion gas generated at the time of ignition does not leak into the opening between the piston and the cylinder. If combustion gas leaks, the engine cannot output sufficient power, increasing fuel consumption?not good both in terms of economy and the environment.

Function2.Lubricating oil film control

Piston rings usually make necessary minimum lubricating oil film for preventing scuffing.

Figure 2. Lubrication oil Since gas ignition is repeated many times, the piston goes up and down inside the engine at a rate of several thousand times per minute. A small amount of oil is poured over the pistons so they move smoothly, with little friction between metal and metal. Piston rings adjust the amount of oil.

Function3.Heat transfer

Piston rings transfer heat from the piston crown to the cylinder.

Figure 3. Heat transfer When gas ignition takes place, the temperature inside a piston reaches approximately 300 C. If heat accumulates inside the piston, the engine may be damaged. For that reason, it is necessary to release the heat build-up. Piston rings help release this heat.

Function4.Support piston in the cylinder

Piston rings prevent the piston from knocking on the cylinder wall.

Figure 4.Receiving force for piston ring If the piston inclines inside the cylinder, it may touch inside parts and cause engine failure as well. Piston rings support pistons to allow for smooth up and down motion.