GB961705A - Improvements in or relating to vehicle suspensions - Google Patents

Abstract

961,705. Hydropneumatic suspension systems. EATON AXLES Ltd. March 28, 1961 [April 4, 1960], No. 11859/60. Heading B7D. [Also in Division F2] A continuous flow vehicle hydropneumatic suspension system including a spring unit 1 comprising a cylinder 31 and piston 33 is characterized in that high pressure hydraulic fluid is supplied direct to the spring unit by an engine-driven pump 10 and the cylinder incorporates a valve 15 for releasing the fluid to a return line 16, the opening of which is controlled by the position of the piston in the cylinder. In the preferred embodiment to prevent settling of the vehicle when stationary, fluid is prevented from passing back through line 12 by non- return valve 14 and through return line 16 by a shut-off valve 17 which is opened by pressure fluid acting through line 18 against a spring- loaded piston when the pump is operating. Alternatively, the valve 15 may be so constructed that it is sealed when shut. In the spring unit shown in Fig. 3 cylinder 31 is attached to the unsprung portion of the vehicle and communicates through passage 32 with a chamber which contains the gaseous spring medium. The piston 33 is connected to hanger bracket 35 mounted on the vehicle body by a resilient member 36, contact of member 36 with face 47 on the hanger bracket stiffening the suspension on large upward wheel movements. Stop member 45 contacts face 46 of cylindrical member 34 to limit rebound movement. Hydraulic fluid from the pump enters the unit through inlet 50 and is released through outlet 51 which is of elliptical or rectangular section and may be cut off by edge 52 of piston 33 to control the vehicle height. A spool valve may alternatively be used to control the vehicle height actuated either by a cam surface on an extension of the piston contacting the end of the valve spool member or by a cam surface on the spool contacting the piston (Fig. 4).