| 摘要 |
1469305 Power steering ROBERT BOSCH GmbH 16 July 1974 [17 July 1973] 31381/74 Heading B7H In an hydraulic servo steering system comprising a control valve 1 having a spool 3 operated in response to actuation of a steering wheel (not shown) to control pressure supply to servomotor 70, the pressure also acting on the spool end faces 29, 33 to act as a restoring force, a device 46 is provided for interrupting the pressure supply from the control valve to the servomotor and simultaneously connects an accumulator 37 to the servomotor in response to the working pressure reaching a predetermined value. As shown in Fig. 1 on deflection of the steering wheel, spool 3 is moved to the left by lever 7 therefore pressure supply from line 15 flows through connecting bore 28, chamber 30, line 43, and via grooves 60, 66 of the control device 46 and line 68 to the working chamber 69 of servo 70. The righthand chamber 73 of the servo is connected to the right-hand reaction chamber 34 by line 72, annular grooves 66<SP>1</SP>, 60<SP>1</SP>, and line 44. Chamber 34 is then connected to return line 21 by connecting bore 32 and annular grooves 26, 18, and passage 20. Movement of spool 3 to the right causes operation of the servo in a similar manner to the above. When a predetermined working pressure is reached, e.g. during high resistance at the wheels at slow speeds, the end face of spool 48 of device 46 is subjected to the pressure via passage 62, and port 63 in spring abutment plate 51, and spool 48 is displaced against the force of initially stressed spring 52, whereby annular groove 60 is closed and communication is established between the accumulator 37 and working chamber 69 via line 59, central annular grooves 58, 66 and line 68. Similar communication may be established between the accumulator and working chamber 73. In a modification, Fig. 2 (not shown), a pressure reducing valve limits the pressure supplied from accumulator 37 to the control valve 1. |
