Reciprocating piston seal for engine or compressor has ring shaped to leave graduated oil film on cylinder surface

摘要

The piston (2), reciprocating in the cylinder of an internal combustion engine or compressor and dividing its chamber (4) into high pressure (6) and low-pressure (8) sections, has a groove (24) containing a closed elastic seal ring (22) designed to leave a graduated film of oil, preferably between 0.1 and 1 mcm thick on the inner surface (12) of the cylinder as it moves from the high-pressure to the low-pressure chamber. The seal ring, which has a radial thickness between 1 and 5 per cent of the cylinder's diameter, has a perimeter that is slightly greater in its free state than the perimeter of the cylinder surface so that it is subjected to a constant elastic deformation.