Patent GB-1056266-A (GB)
Title: Improvements in hydro-pneumatic suspension units for vehicles
Inventor: WILKINS DOUGLAS BRYAN
IPC: B60G15/12
Filed: 1962-10-17
Abstract: 1,056,266. Hydro-pneumatic suspension units. GIRLING Ltd. Oct. 14, 1963 [Oct. 17, 1952], No. 39245/62. Heading F2S. A hydro-pneumatic suspension unit comprises a piston 25 working in a cylinder 11 to draw liquid from a reservoir 10 to increase the length of the unit, one end of the cylinder 11 being provided with a closure 14. A valve opening 16 in the closure connects the cylinder to the reservoir but is closed by a valve member 19 to prevent flow of liquid to the reservoir when the piston 25 reaches a predetermined position in the cylinder. In the construction shown in Fig. 1 an axially extending stem 21 which carries the valve member 19, is mounted in nylon or other bearings 22, 23 of a sleeve 24 which in turn is mounted in the piston 25. The lower end of the stem 21 is provided with a disc 26 which is able to reciprocate in the bore 27 of the piston rod 28 against a spring 29. The cylinder 11 of the shock absorber is connected to the hydropneumatic pressure chamber 13 through valved passages 15. On the up-stroke of the piston liquid is drawn from the reservoir 10 into chambers 31, 32 through valves 33 and when the piston changes direction this liquid is pumped into the high pressure chamber through valve 37. If too much liquid is pumped into the high pressure chamber the piston is depressed to engage the disc 26 and open valve 19, 20 to allow the liquid to pass into the reservoir through passages 16, 17, 18. The valve member 19 comprises a resilient rubber or the like disc or washer mounted in and standing proud of a recess which has an internal diameter slightly greater than that of the valve seat 20. Radial slots may be formed in the rim of the recess. The valve may comprise a conical valve member formed at the end of stem 21 and mating with a conical valve seat in the closure 14 of the working chamber (Fig. 2, not shown). In a modification (Fig. 3, not shown) the valve comprises a plunger sealed in and slidable in an axial bore in the closure 14, the upper end of the plunger being held normally against a valve seat in the closure by a helical spring working between the upper face of the piston and the lower face of a disc attached to the plunger. When the effect of the helical spring is decreased on the shock absorber extending. beyond its riding position the plunger is forced away from its valve seat by a further helical spring abutting the upper surface of the plunger disc. In a further embodiment (Fig. 4, not shown) an inflatable, longitudinally fluted bag 88 may be introduced into the reservoir 70. The reservoir communicates with the high pressure chamber through an annular space 76, valve 81, the bore 79 of the piston rod, and valve 80, liquid flowing along this path through the reciprocations of the axial valve stem 77 and collar 84 in the bore 79 of the piston rod. The relief valve seat is formed on a plug 65 secured in the closure 61. A one-way valve 90 is provided for filling the shock absorber with liquid. In a further shock absorber (Fig. 5, not shown), two valve seats are provided in the cylinder closure, one surrounding a bleed passage to the reservoir and the other surrounding a one-way valve which allows liquid to be drawn from the reservoir into the high pressure chamber. The axial spring-loaded valve stem is provided with an axial bore and its lower end is held within the piston for limited longitudinal movement with respect to the piston. The reservoir space is divided by a stationary ring, the upper half acting as the reservoir and having an inflatable bag mounted therein and the lower half being provided with a diaphragm of sleeve form being clamped at the inner periphery of the stationary ring at one end and the wall of the reservoir chamber at the other. The chamber so formed between the diaphragm and the wall of the reservoir space is filled with gas, while the other chamber is in communication with the lower face of the piston.