GB865359A - Improvements in or relating to automatic levelling suspensions for vehicles - Google Patents

Abstract

865,359. Road vehicle spring suspensions; springs. THOMPSON PRODUCTS Inc. Nov. 11, 1957, No. 35100/57. Classes 108(2) and 108(3). In a continuous-flow automatic levelling system for vehicles a hydropneumatic strut 17, Fig. 1, is pivoted to a rear axle housing 14 at joint 18 and to a plane member 10 at joint 19. In the independent suspension of the front wheels the strut is mounted between a pair of lower wishbones and the frame 10. Pressurized hydraulic fluid from a pump 21 is supplied to the strut 17 through a conduit 23. Fluid leaves the strut through a conduit 24 and passes to a reservoir 25 through a lockout valve 22. Member 32, Fig. 4, slides in a member 30 to pump fluid to and from chamber 38 through damping orifices 41, 39 and 40. The pneumatic spring is formed by an outer housing 34 and a bladder member 35 between which in chamber 20 is air under pressure. As fluid enters through the conduit 23 it passes through a check valve 45, conduit 46 and past needle valve 47 through orifice 48 and into chamber 33. Needle 47 may be biased by a spring 52, bent, or provided with a bush to damp out oscillations which cause noisy operation. If a bush is provided it must be perforated or the needle fluted to provide a path for fluid. Fluid continuously leaves chamber 33 through a calibrated orifice 60, which contains a filter, and a check valve 68. Conduits 23, 24 may be provided with heat exchanger elements to warm or cool the circulating fluid. To prevent buckling of needle 47 by rapid oscillations a by-pass 71 is provided between chambers 70 and 33. A check valve 72 closes the by-pass except when a high pressure is built up in conduit 46. Spherical portion 80, 80a, of joint 18 is held against a liner 84, of nylon or polyethylene, by socket member 81. The joint at the top of the strut has a conical rubber mount 90 with an outer metal shell 93 which is held in position within the frame 10 by a clip 95. An inner sleeve 98 of the mount 90 is secured to member 32 by snap ring 97. The conical shape of the mount 90 and the shape of backing plate 99 provide a variable-rate spring. Lockout valve 22, Fig. 1, prevents collapse of the struts when the supply of pressure fluid fails by closing the outlet conduits 24. Plunger 22a is held in the position shown in Fig. 1, by pressure applied to chamber 22c through conduit 112. When the pressure drops, plunger 22a is raised by spring 22b, thus moving passage 22d out of alignment with conduit 24 to prevent escape of fluid from the struts. Check valve 115 prevents opeing of lockout valve 22 by accidental leakage of pressure from chambers 33 past the individual check valves 45.