Hilfskraftlenkung,insbesondere fuer Kraftfahrzeuge

摘要

1281185 Power assisted steering mechanism ZAHNRADFABRIK FRIEDRICHSHAFEN AG 18 Dec 1969 [21 Dec 1968] 61804/69 Heading B7H A power assisted steering system is of the kind having a servo pump for delivering a pressure medium, a valve for controlling the pressure medium, a steering gear casing subdivided by an hydraulic piston into two pressure chambers, a rocker shaft mounted in the casing, and a recirculatory ball nut mounted for rotation in the piston and co-operating with a worm by balls engaging the nut. The ball-nut 13, Fig. 1, has a driving member 14 with an end 15 engaging a bore 16 of a control valve 17 disposed transversely of piston 7. The valve 17 has a member 22, Fig. 6, guided in a bush 27 and a radial bore 25 engaging the end 15 of the member 22. Reaction pistons 30, 31 are disposed in discs (32), (33), Fig. 5 (not shown), secured to piston 7 by screws 32, 33, Fig. 6. A centring device 45, Fig. 5, fixes the position of the nut 13 and control valve 17 in the central steering position which may be adjusted by grub screws (51), (52), Fig. 8 (not shown). Pressure medium is fed to the valve 17 through grooves, 55, 56, Fig. 6, communicating through bores (57) (58), Fig. 4 (not shown), in the piston. Inlet and outlets 60, 61, Fig. 6, are provided in the casing 3 to connect with the grooves 55, 56. Pressure medium flows in one direction to pressure chamber 8 through the valve 17, Fig. 5, through a groove 23 in member 22, a channel 68, a chamber 69 and bores 21 in a ring 20 and in the other direction through a groove 24, channel 71 to pressure chamber 9. When a steering wheel on a splined shaft 1 is stationary pressure medium flows through the valve 17 between inlet 60 and outlet 61. However, when a steering movement is effected worm 2 rotates and by means of the balls 18 moves the ball nut 13, and piston 7, e.g. downwards, Fig. 1, the pressure medium flows into chamber 9 and from chamber 8. The pistons 30, 31, Fig. 5, are differentially loaded to produce differential pressure on valve member 22 so that the driver experiences "feel" associated with a mechanical steering system. In another embodiment, Fig. 2 (not shown), a piston (107) has a blind base and the ball nut (113) is above rocker shaft (111). In a further embodiment, a short rocker shaft (111), Fig. 9 (not shown), has a sector (101) projecting into a pressure chamber 91. A modified control valve (124), Fig. 11 (not shown), has reaction pistons (136), (137) adjustable for centring by set screws (140), (141) having eccentric portions (142), (143).