Piston Ring is the mental ring used for embedding inside the piston
groove. It is of two kinds: compression ring and oil ring.
Compression ring can be used to seal the combustible gas mixture in
combustion chamber; Oil ring is used to shave the redundant oil on
the cylinder. Piston ring is a bigger outward expansible deformable
of metal elastic ring, assembled into section and its corresponding
Depending on the pressure difference between the gas or liquid,
reciprocating and rotating piston rings form the seal between the
side of , in ring cylindrical surface and cylinder and ring and
ring groove formed between a lateral seal.
The effects of piston rings include seal, oil-adjusting (
oil-controling), heat conduction (heat transfer) and direction
(supporting). Seal refers to sealing gas, preventing the gas in the
combustion leaking into the crankcase, controling the gas leakage
at a minimum and improving the thermal efficiency.
Gas leakage not only decreases the engine power, but also makes the
oil metamorphic, which is the main task of the gas ring.
oil-adjusting ( oil-controling) is to scrape excess lubricating oil
on cylinder wall , and also make a thin oil membrane on the
cylinder wall to make sure normal lubrication of cylinder, piston
and rings, which is the main task of the oil ring.
In the modern high-speed engine, the effect of piston ring
controling oil film is paid a special attention. Heat conduction is
to transfer the heat from piston rings to cylinder liner, namely
cooling effect. According to reliable information, 70 ~ 80% of the
heat of the piston top in the non-cooling piston is radiating from
piston ring to cylinder wall, while there is 30-40% of the heat for
a colling piston.
Supporting is to keep the piston in the cylinder, prevent direct
contact bwtween the piston and cylinder wall, ensure smooth
movement of piston, reduce the friction resistance, and prevent the
piston knocking cylinder. The piston of general gasoline engine
uses two gas rings and one oil ring, while diesel engines usually
adopts two oil rings and one gas ring.