| 摘要 |
<p>PURPOSE:To secure fail-safe by suppressing the heavy feeling in the steering wheel operation due to the trouble of an electric motor, by prohibiting the engagement of a clutch for transmitting a power assisting power when the revolution operation of the electric motor is not detected. CONSTITUTION:A controller 60 receives the signals of a car speed sensor 64 and detects the magnitude and direction of the steering torque of a steering wheel 10 from the signal of a torque sensor 66. If the steering wheel 10 is steered during the low speed traveling, an electric motor 38 is driven in the same direction through a polarity selecting circuit 52, and the electric current having the duty ratio corresponding to the detected torque is allowed to flow in an electromagnetic powder clutch 28, and a steering main shaft 12 is power- assisted. If the revolution of the electric motor 38 is not detected by an electric motor operation sensor 69 because of a trouble, etc., a control circuit 60 prohibits the electric conduction to the electromagnetic powder clutch 28. Therefore, even if the electric motor fails, the heavy feeling in the steering wheel operation can be suppressed, and fail-safe can be secured.</p> |
