Patent GB-1040802-A (GB)
Title: Improvements in vehicle suspensions
IPC: F16F9/516
Filed: 1964-03-02
Abstract: 1,040,802. Vehicle suspensions. RECHERCHES ETUDES PRODUCTION. March 2, 1964 [March 2, 1963 (2); Jan. 13, 1964; Feb. 17, 1964], No. 8728/64. Heading B7D. [Also in Division F2] A vehicle hydropneumatic suspension system comprises a system of hydraulic suspension members V 1 , V 2  connected in parallel with the output of a pump 3 through a valve having a spool 8, supply outlet 13, feed line 14 from the pump and return conduits 16 and 17 to the reservoir 1. The pressure fluid supply line 13 is connected to the central chamber 12 which is also connected to a chamber 4 in which is located an air spring 5. The reservoir 1 has connections 20 and 21 to the ends of the valve chamber and the valve spool is connected to the vehicle axle by a blade spring 11 or by a system of levers so that an increased load connects the lines 13 and 14 through the chamber 12 until the level is restored, and vice versa. The reservoir 1 is vented to atmosphere through 2<SP>1</SP> and lines 18<SP>1</SP> and 18<SP>2</SP> restore leakage fluid from the suspension units to the reservoir. The pump 3 may be actuated by a belt drive or by a flexible shaft, or, as in a modification, Fig. 2 (not shown), by an electric motor 22 delivering directly to the chamber 4 which is connected directly to the suspension units by the line 13. The motor 22 is operated from the vehicle battery by a relay 23 in series with a pair of switches 24, 29. When the vehicle is laden, the valve spool rises and the switch 24 is closed, whereby the motor is actuated, delivering fluid to restore the vehicle height. When the vehicle load is diminished, so that the valve spool 8 falls relatively to its housing, the switch 24 is opened whereby the motor ceases to operate, and the suspension units and chamber 4 are connected to reservoir through lines 26, 28 and the valve groove 27. The switch 29 is an overload safety device actuated by excessive pressure in the line 26. Each suspension unit, see Division F2, may comprise a cylinder 40 and piston 32 which is formed with central member 33 upon which is mounted a piston having passages 39 with which co-operates a flap valve 38. At the top of the cylinder a member 44 is provided with a member 41 having passages 47, 43, and a flap valve 42, there being lateral clearances between the member 41 and cylinder as shown. When the piston is performing an up stroke, liquid passes relatively freely through the passages 39 and through the clearance between the member 41 and cylinder with some throttling. On the down stroke, liquid may enter the cylinder freely through the passages 43 and the transfer of liquid from one side to the other of piston 35 occurs, with throttling, through the clearance 34 and bore 50 of the member 33. In a modification, Figs. 3 and 4 (not shown), the piston rod 53 has an extension 55, 56 of stepped diameters upon which is slidable a piston member T 1 , T 2 , also of stepped diameters which have passages 59, 60, 61, 62 and lateral clearances 57 and 58. The piston T 1 , T 2  co-operates with sealing rings 66 and 67 at the upper and lower limits of its movement. On an up-stroke of the piston, the member T 1 , T 2  seats against the seal 67 as in Fig. 3, and the liquid takes the path indicated by the arrows, and on the down stroke, the piston member T 1 , T 2  seats against the seal 66, the passages 59, 60 thus being closed, and the liquid passing through the clearances 58, 57 with throttling.