Patent GB-1165692-A (GB)
Title: Improvements in or relating to vehicle Suspension Systems
Inventor: LEGGETT THOMAS OSBORN
IPC: B60G17/04
Filed: 1965-07-08
Abstract: 1,165,692. Regulating vehicle height. SECRETARY OF STATE FOR DEFENCE. 6 Oct., 1966 [8 July, 1965], No. 29013/65. Heading B7D. [Also in Division F2] A vehicle suspension comprises a damping means consisting of a tubular reservoir 11, a piston 7 located therein and a hydro-pneumatic container 14 connected to the reservoir for receiving liquid from and discharging it into the reservoir in accordance with relative motion between the reservoir and the piston due to vertical movement between the vehicle body and a wheel of the vehicle, the piston having mounted therein a valve 16 which is urged to its closed position by a spring 17 and is moved into its open position to permit discharge of liquid from the reservoir to the hydro-pneumatic container 14 as the capacity or effective volume of the reservoir is reduced by relative motion between it and the piston, there also being provided an intermediate chamber 10 arranged between the reservoir and the hydropneumatic container having associated therewith a second valve 20 which can cut off the flow of liquid between the reservoir and the hydro-pneumatic container. As shown, a toroidal cylinder 1 works over a correspondingly-shaped piston 7 and is carried on an arm 2 secured to a shaft 3 which is rotatably mounted in bearings in a bracket 4 on the vehicle chassis 5 and which carries a radially disposed axle arm, not shown. The piston 7 is carried on a base plate 9 secured to the bracket 4, the intermediate chamber 10 communicating with a hydro-pneumatic pressure accumulator 14 by means of a tube 13. An opening 12 in the piston 7 is controlled by the spring-loaded valve 16 which has bores 19 to damp the rebound stroke of the cylinder 1. An opening 21 in a web 22, which divides the intermediate chamber 10 into compartments A and B, is controlled by the poppet valve 20 the stem 20a of which carries a piston 24 which is slidable in a cylinder 25 fixed to the plate 9, is urged upwardly by a spring 23, and which carries a stop 26 to form an annular control space above it. The chambers 10, 11, the pipe 13 and the lower chamber of the accumulator are filled with hydraulic liquid, a flexible container 15 in the accumulator being filled with gas under pressure. The container 15 may be replaced by a separating diaphragm. The accumulator 14 can be isolated from the intermediate chamber 10 by feeding liquid under pressure into the annular space above the piston 24 so that the wheel axle and the vehicle body are maintained in constant relative positions. Pressure liquid can also be fed or withdrawn from the pressure chambers 11 of the several shock-absorbing devices so that the initial height and inclination of the body can be adjusted. A balance for the system comprises a positional sensing means consisting of a cam 27 on the pivotal arm 2, a cam follower 44 on one end of a leaf spring 45 on a switch 46 which controls a valve which enables liquid to be supplied to, or withdrawn from, the compression chamber 11. The sensing means may also control the poppet valve 20. An hydraulic control for the system, Fig. 2, comprises a pump 30 which draws liquid from a reservoir 28 and, in one circuit, delivers it, through a pipe 31 to a manually-operated twoway distributing valve 32 which can be connected through a pipe 33 to the annular space above the piston 24 or, connect the pipe 33, through a non-return valve 35 and pipes 34, 36, to exhaust into the reservoir 28. With the valve 20 closed the volume of liquid in the pressure chamber 11 can be increased without altering the pressure in the accumulator 14 and thus the height of the vehicle body can be increased by supplying liquid from the pump 30 to a branch pipe 37 leading to a threepositional distribution valve 38. The latter can be actuated (a) to cut off flow of liquid therethrough; (b) to connect the main outflow pipe 31 to a secondary pipe 39 leading to a bore 40 in the piston 7 to supply liquid to the compression chamber 11; or (c) to connect the pipe 39 to the exhaust pipe 36 through a pipe 41 having a non-return valve 42. Under this control the body can be raised or tilted as required. In a third control circuit for balancing the system when the poppet valve 20 is open the switch 46 is arranged in series with a manually controlled switch 49 and a solenoid 47 for operating a valve 48 which, when the solenoid 47 is energized, supplies liquid, through a branch pipe 50 having a regulating valve 51 and a pipe 52 provided with a regulating valve 53, to the pipe 39 leading to the compression chamber 11. At the same time connection is made between a pipe 54, having a pressure relief valve 55 and connected to the pipe 13 between the intermediate chamber 10 and the accumulator 14, and a pipe 56 which includes a non-return valve 57 and which leads to the exhaust pipe 36. A branch pipe 58 leads from the pipe 13 and incorporates a pressure relief valve 59 and a non-return valve 60 connected to the exhaust pipe 36. The valve 59 is adjusted to wheel bump pressure.