Sealing ring for inside wall of cylinder - is low friction polymer, e.g. PTFE, filled with fibres disposed circumferentially so as to have same thermal expansion as cylinder itself

摘要

A sealing ring is set in an annular groove on the i.d. of a cylinder so as to seal the space between the cylinder and a moving component inside it. The main body of the ring is made of a polymer contg. a filler which is mixed in to produce a ring whose coefficient of thermal expansion is the same as that of the cylinder itself. Pref. material is a fluoropolymer with mixed carbon and asbestos fibres as filler. A ring is fitted in the groove (3) on the i.d. of a cylinder (2) so as to seal the moving component (4) in the cylinder (2). The ring is made of e.g. PTFE (or nylon) with low friction and high wear resistance and is filled with (e.g.) carbon fibres (6) to reduce the thermal expansion of the ring. ADVANTAGE - The seal is simple to produce. It is highly effective. It does not increase the min. pressure required because of an dimensional difference between the seal and cylinder.