Sealing device

An assembly for an alternating internal combustion engine or alternating compressor comprising:

• at least one chamber having a circular cylindrical sliding surface,
• a piston designed to move in alternating linear movement parallel to the axis of the sliding surface dividing the chamber into a high pressure volume and a low pressure volume,
• a sealing device between the piston and the sliding surface, the sealing device including
• a sliding surface partly bounding the chamber, and defining a perimeter,
• an annular groove provided in the piston which is coaxial with the sliding surface and opened towards the sliding surface,
• a closed resilient metallic sealing ring having a uniform cross section and a sealing bearing surface, the ring being housed within the groove in leak tight fashion, and being in sealing contact with the sliding surface, through said sealing bearing surface, said sealing bearing surface having a perimeter, said perimeter of said sealing bearing surface in the free state being slightly greater than the perimeter of the sliding surface so that the sliding surface imparts permanent resilient compression deformation on the ring which brings about a substantially uniform bearing pressure between the bearing surface and the sliding surface when the ring is resiliently held tightly against the latter, and
• a lubricating oil film between the ring and the sliding surface which is sized by the ring to a limit lubricating thickness of 0.1 μm to 1 μm when the ring moves from the high pressure volume to the low pressure volume.