High-pressure seal in piston

Claim 1

In a piston and cylinder arrangement wherein the piston has an annular recess therein adjacent a high-pressure area defined between the piston and the wall of the cylinder, high-pressure seal means mounted in said recess, comprising: a one-piece backup support ring defining together with the cylinder wall a first, annular sealing chamber; an annular, elastomeric dynamic seal ring disposed in said chamber; said support ring further defining together with the piston a second, annular sealing chamber; an annular, elastomeric static seal ring disposed in said second chamber; said second chamber being defined by a pair of spaced apart end faces and a pair of spaced apart conical faces extending therebetween; said recess having an annular side wall lying parallel to the piston axis and an end wall lying perpendicular thereto; said conical faces sloping radially outwardly in a direction toward said end wall; and said static seal initially encircling said side wall and being shifted into said second sealing chamber by said support ring upon assembly thereof; said static seal being radially expanded by said conical faces when disposed in said second sealing chamber to thereby tightly engage said piston, whereby to improve the seal between said piston and said cylinder.