GB1306963A - Pressure sealing assembly - Google Patents

Abstract

1306963 Piston-rings; shaft seals GARLOCK Inc 14 May 1970 [27 May 1969] 23448/70 Headings F2B and F2T A seal for a piston or rod comprises a split sealing-ring 17, Fig. 1, which is constantly urged, either by its own resilience or by biasing means, into sealing contact and an endless elastic retaining ring (or rings 21, 23) which provides a radial retaining force on the splitring to reduce the bearing pressure and which expands or contracts as the split-ring is worn away to allow the split-ring to remain in sealing contact. In the piston seal shown, the endless elastic rings 21, 23 permit a uniform pressure to be applied by the split-ring throughout its life. The split-ring may be formed as a spring-ring or as a spring-urged segmental ring and made of P.T.F.E. or metal. The endless rings 21, 23 may be made of metal or plastics having a modulus of elasticity which permits a uniform bearing pressure of the split-ring throughout the life of the split-ring, the modulus being determined by the maximum radial forces occurring in the cycle of the piston. After initial wear of the split-ring 17, clearances 29, 31 are taken-up and the endless rings 21, 23 are stretched into sealing contact. In the rod seal shown in Fig. 3, after the initial wear of the split-ring 37 the endless ring 39 is placed in compresssion and pressed into sealing contact with the rod 35. In Fig. 4 (not shown) the splitring is of T-section and is urged towards the rod by an O-ring (61) having a tensile modulus of elasticity related to the compressional modulus of elasticity of the endless rings (57, 59). In another embodiment, a pair of L-section splitrings co-operate with a single endless ring. In further embodiments, the split-ring is of C- or H-section with the endless rings arranged in the section so that they do not come into sealing contact with the cylinder or rod. Relative rotation between the rings may be prevented by interengagement.