| 摘要 |
PURPOSE:To enhance reliability of a power steering gear, by a method wherein a torque retaining circuit for passing an electric current to a motor is provided with an electric current value for securing the minimum driving torque required for driving the motor when a steering wheel is operated. CONSTITUTION:A pump 14 for supplying a working fluid to the power steering gear 12 is driven by the motor 13, which has a field winding 13a and an armature winding 13b connected to a controlling circuit 16. The controlling circuit 16 is constituted of a vehicle speed-to-voltage converting circuit 22 to which a vehicle speed detecting means 17 is connected, a rotational frequency-to-voltage converting circuit 21 to which a detecting means 18 for the rotational frequency of the motor 13 is connected, a comparing circuit 22, a transistor 33, the torque retaining circuit 32 consisting of a resistor 30 and a transistor 34, and an armature current controlling circuit 26 to which a steering operation detecting means 19 is connected. The torque retaining circuit 32 receives an output from the steering operation detecting means 19, and so functions that an electric current of a predetermined value for retaining a driving torque for the motor 13 is passed from a power source 25 to the field winding 13a. |
