GB1396718A - Sealing device for piston rods of dampers and similar devices especially for vehicle suspensions - Google Patents

Abstract

1396718 Seals; self-levelling suspension units F M ALLINQUANT and J G ALLINQUANT 14 Dec 1972 [17 Dec 197.1] 57811/72 Headings F2B and F2S A sealing arrangement, e.g. for a piston-rod 3 of a self-levelling suspension unit, Fig. 1, comprises a. sealing cuff 40, Fig. 2, clamped to engage the rod 3, and a lip seal 43, a chamber 35 between the cuff 40 and seal 43 being maintained at a pressure between the external pressure and that in a working cylinder 1. The cuff 40, preferably of ptfe, is clamped adjacent a selflubricating guiding ring 39 by a ring 42, screwed into a bore 32 and acting through an 0-ring 41. The lip seal 43, having three sealing lips 43c, is positioned by a screwed ring 44, a support ring 47 further being provided. The suspension unit includes a cylinder head portion 5 bearing a hollow plunger 4 within the working cylinder 1, the piston-rod 3 sliding on the plunger 4 and having a piston 2. Elastic membranes 8, 17 define closed compressed air spaces 9, 18 and oil reservoirs 7, 16. In operation of a vehicle including the unit, reciprocation of the piston 2 causes oil to be drawn into the cylinder 1 from the reservoir 7 through passages 10, 11, a chamber 6 and non-return valves 10a, 11a. Oil from a cylinder space 13 is forced through a channel 15 into the reservoir 16 causing a pressure build up on the membrane 17, the air space 18 acting as a pneumatic supporting spring. Continued pumping of oil into the upper cylinder space 14 acts on the piston 2, causing the unit to expand until the piston 2 uncovers an aperture 20 leading to an internal annular passage 19 within the plunger 4, a connecting passage 21 leading the oil back to the reservoir 7, so that further expansion is halted, the unit taking up an equilibrium position with the passage 20 just uncovered. Valved passages 2a, 2b through the piston allow for contraction of the unit if extended beyond the equilibrium condition, and passages 25, Fig. 2, (46), Fig. 3 (not shown), within the wall of the cylinder 1 connect the chamber 35 of the sealing arrangement to the oil reservoir 7, so maintaining the pressure in the chamber 35 at a level below that in the cylinder space 13 adjacent the sealing arrangement.