High pressure self-contained gas spring or die cylinder and sealing

Abstract

A self-contained gas spring or die cylinder including a cylindrical housing having a closed end, an open end and a cylindrical bore. A cylindrical sleeve extends into the bore of the housing and has at least a portion thereof forming an internal cylindrical surface. A piston rod extends through an opening in the sleeve and has a piston thereon contacting the cylindrical surface. The piston rod is hollow and has a closed end in the portion thereof external of the cylindrical housing. The sleeve supports a first seal assembly adjacent the inner end of the rod and engaging the external surface of the rod, an intermediate slide ring on the sleeve and a secondary seal assembly on the sleeve positioned such that the slide ring is between the primary seal and the secondary seal. The primary seal assembly is of the pressure relieving type so that on the inward movement of the piston rod a portion of the pressure within the housing passes to an intermediate area between the primary seal assembly and the secondary seal assembly such that the secondary seal assembly shares the sealing action with the primary seal. In a modified form, a third primary seal is provided on the sleeve between the sleeve and the cylindrical housing.