GB1046321A - Improvements in or relating to power-assisted steering arrangements, particularly for motor-vehicles - Google Patents

Abstract

1,046,321. Power asisted steering. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. Jan. 20, 1964 [Jan. 19, 1963], No. 2411/64. Heading B7H. Control passages in a motor vehicle powerassisted steering system are provided by annular spaces between two-part valve members or two-part housing members. The steering assembly, Fig. 1, comprises a steering mechanism 5 having a drop arm 8 articulated by a ball-pin 20 (Fig. 3), to a housing member 18 of a power steering device which is connected between the vehicle frame 28 and the steering linkage 10. The power device, Fig. 3, comprises housings 18, 14 and 32, the latter enclosing with an annular space 33, a power cylinder 12 in which operates a piston 25, the space 33 communicating by a bore not shown, with the cylinder space 31 and with a fluid passage 46 in the housing 14 which also has a bore 35 for receiving a valve member 36 and a fluid passage 47 leading to the cylinder space 30. Annular grooves 37, 38 and 39 are formed in the bore 35, the grooves 37 and 38 being connected, respectively, by fluid lines, not shown, to reservoir and a pressure supply. The valve member 36 has radial bores 55, 56 leading to an axial bore 50 in which is located with an annular clearance 54 a member 48 having an axial bore 57, 59 affording communication between the ends of the valve. The valve has a reduced diameter portion providing a shoulder 67 with which and with a shoulder 68 in the bore 35 co-operates a disc 69 subjected to the pressure of a spring 64 which, at its other end, abuts a collar 72 slidable on the valve member. The valve member has further reduced diameter portions upon which are located a ring 79, spacer 79<SP>1</SP> and disc 75. Movement of the collar 72 to the left is prevented by a disc 70 and the ring 79 is clamped in a seating member 78 for the ball-pin 20, there being a space between each end of the member 78 and the housing 18 providing the valve control backlash. When a steering movement is performed, e.g. so that the ball-pin 20 moves to the right, the valve member 36 is moved to the right and the cylinder space 31 is pressurized through passage 46, and grooves 40 and 38, the cylinder space 30 being opened to reservoir through passage 47, grooves 41 and 39, radial bores 55 and 56, annular space 54 and groove 37. The valve exercises a similar function when an opposite steering function is performed, the centering spring 64 again being compressed and the cylinder spaces 30 and 31 being pressurized and exhausted, respectively. In the central position of the valve, pressure fluid from groove 38 passes via grooves 40 and 41 into the exhaust grooves 37 and 39. In a modification, Figs. 4 and 5, a valve member 90 is enclosed in a two-part housing 80, 81 and the power piston 88 works in a cylinder 83 enclosed within a housing 84 with an annular space 85<SP>1</SP> which communicates with the cylinder space 87 and by passages 99<SP>1</SP>, 99 with a radial passage 100. The cylinder space 86 is connected to passages 101 and 101<SP>1</SP>. A fluid supply passage 107 in the housing is connected via passages 106 and 112 to the space 108 containing the centering spring 113. The valve member has grooves 94, 95 and a central axial bore 116 connecting the ends. The housing member 81 has grooves 91 and 93 connected by passages 118, 117, 119 and a groove 92 connected to the supply passage 107. Groove 91 is connected via a groove 105 to exhaust. If the valve spool is displaced, e.g. to the right, the pressure fluid from groove 92 enters groove 94 and flows to the cylinder space 87 via passages 100, 99, 99<SP>1</SP> and annulus 85<SP>1</SP>, while fluid from space 86 returns to reservoir through passages 101, 101<SP>1</SP>, grooves 95, 93, passages 119, 117, 118 and grooves 91 and 105. The valve functions similarly when moved to the left for pressurizing cylinder space 86 and exhausting space 87.