Piston ring is
widely used in various power machines, such as the steam engine, diesel
engine, gasoline engine, compressor, hydraulic machine and so on. And
it mainly has four functions including sealing effect, adjusting the
oil, heat conduction, and supporting.
Sealing refers to sealing
the gas, in order to prevent the leakage of gas from combustion chamber
into the crankcase, control the amount of gas leakage to a minimum, and
improve thermal efficiency. Because leakage of the gas will not only
make the engine power decline, but also lead to the oil deterioration.
Adjusting
oil is to scrape the surplus lubricating oil on cylinder wall, and at
the same time to make a thin oil film so as to guarantee normal
lubrication of cylinder, piston and piston ring. In modern high speed
engine, special attention has been paid to the effect of controlling of
oil film of piston ring.
The heat conduction is to conduct the
heat from the piston to the cylinder sleeve through the piston ring,
that is, to receive the cooling effect by the piston ring.
The supporting role means that the piston ring keeps the piston remaining in the cylinder, which can prevent direct contact between the piston and the cylinder wall, ensuring the smooth movement of the piston, reducing the friction resistance, and preventing the piston knocking cylinder.