GB1359208A - Hydraulic power-assisted steering unit especially for motor vehicles - Google Patents

Abstract

1359208 Power steering AUTOIPARI KUTATO INTEZET 14 July 1971 [18 July 1970] 33114/71 Heading B7H In an hydraulic power-assisted steering unit, the steering box 1 is closed by covers 5, 6 at its ends and contains a power piston 9 working in chambers 2, 3. The steering shaft 14 turns a nut 12 which carries one end of a two-armed lever 39 which is pivoted at its centre by ball joint 40 in a passage 38 formed in piston 9 and operates, at its other end, the control valve spool 16 which is slidable in a housing also formed in the piston 9. Pressure fluid is supplied to inlet 21 whence it flows along passages 22, 23, 24 to annular groove 25. When due to driver steering action in one direction the spool 16 is displaced upwards (Fig. 2) the fluid passes through duct 35<SP>1</SP> to chamber 2 forcing piston 9 to the right (Fig. 1) and when due to opposite direction of driver steering action the spool 16 is displaced downwards, fluid passes via groove 36 and passage 37 to chamber 3, forcing piston 9 to the left. The pressure in chamber 2 exists at both ends of valve spool 16, but since a piston 48 is rigidly attached to one end wall 47 of the valve housing and is slidable in a bore 46 of the spool, the spool is urged downwards (Fig. 2) against the action of spring 50 providing feel for the driver in said one direction of driver steering action which is fed back via lever 39. In the said opposite direction of driver steering action, feel for the driver is obtained if the spool is urged upwards by pressure derived from the chamber 3 acting within an axial bore of the spool.