Rotary piston engine piston inner seal scraper ring - has axial and radial arms with top layer of lower coefficient of thermal expansion than ring proper

摘要

The inner seal is for the piston of a rotary piston machine with a housing assembled from a cover and two parallel side parts. The seal comprises an oil scraper ring (13) with one axial (14) and at least one radial arms (15) and a ring shaped scraping edge. The outer peripheral surface (25) of the axial arm (14) and/or the abutting radial surface (26) of the other radial arms (15) are provided with a layer (27) made of material with a lower heat expansion coefficient than the oil scraper ring (13) itself. This layer can be galvanised, sprayed, cast or plated on.