Abstract: A piston includes a circumferential groove having a seal ring and spring mounted within the groove. The spring exerts an axial force on the seal ring thereby preventing motion of the seal ring within the groove. Preferably, the spring in a wave spring, wherein small changes in deflection of the wave spring produces small changes in the load generated by the spring on the seal ring. The seal ring has at least one radial spring ring mounted within the seal ring to create a radial force on the seal ring. The piston can also include a sleeve that mounts to the piston body, the sleeve forming a wall of the groove. The piston can be a displacer mounted within a cylinder of a refrigerator.

Abstract: A piston includes a circumferential groove having a seal ring and spring mounted within the groove. The spring exerts an axial force on the seal ring thereby preventing motion of the seal ring within the groove. Preferably, the spring in a wave spring, wherein small changes in deflection of the wave spring produces small changes in the load generated by the spring on the seal ring. The seal ring has at least one radial spring ring mounted within the seal ring to create a radial force on the seal ring. The piston can also include a sleeve that mounts to the piston body, the sleeve forming a wall of the groove. The piston can be a displacer mounted within a cylinder of a refrigerator.

Abstract: A rod seal system having a pair of rod seals that form a buffer area between a high pressure area containing working gas and a low pressure area of a heat engine, such as a Stirling cycle engine. A pump that becomes passively charged with working gas at relatively low pressure and which releases working gas at relatively high pressure when actuated is used to force working gas from the buffer area to the high pressure area through a conduit. The working gas may be hydrogen gas and the pump may be a metal hydride pump that is thermally actuated. The low pressure area may contain air and lubricant at atmospheric pressure. A system for separating the lubricant collecting within the buffer area and reintroducing the lubricant into the low pressure area can also be incorporated into the rod seal system.