| 摘要 |
A power steering system for a vehicle which has one or more steerable wheels (10) there is provided a manually operable steering wheel (12), a first angle sensing device (16) connected to the steering wheel (12), a servo motor (13) connected to the steering wheel or wheels (10) and includes a second angle sensing device (15), and a control unit (17) for receiving signals from the first angle sensing device (16) and for energizing the servo motor (13), wherein the first angle sensing device (16) comprises a single digital angle encoder fed with a constant supply voltage (VCC) by the control unit (17) and generating electric pulses of a certain amplitude ( DELTA V1), the control unit (17) includes a malfunction detecting device connected to the angle encoder (16), and the angle encoder (16) comprises a circuit for establishing a constant analogous voltage for reducing the pulse amplitude ( DELTA V1) normally delivered by the angle encoder (16) to a suitable check amplitude ( DELTA V2), wherein the bottom voltage level of each pulse is above zero and the top voltage level of each pulse is below the supply voltage (VCC), and the malfunction detecting device comprises a means for providing high and low trip voltage levels for each pulse delivered by the angle encoder, wherein the low trip voltage level (Vt1) is below the bottom voltage level of each pulse but above zero, and the high trip voltage level (Vth) is above the top voltage level of each pulse but below the supply voltage (VCC). <IMAGE> |
