| 摘要 |
A rear wheel steering system of a four wheel steering vehicle comprising a rear wheel steering mechanism for steering a rear wheel, an urging device for urging a rear wheel toward a neutral position of the rear wheel, a motor connected with the rear wheel steering mechanism for providing the rear wheel with steering force against resilient force of the urging device, a clutch for transmitting a driving force of the motor to the rear wheel steering mechanism, steering position detector for detecting a steered position of the rear wheels, control unit for receiving a signal from the steering position detector and for forming a motor control signal by which the motor is controlled to steer the rear wheel. The steering position detector has at least three detectors for detecting a steered position of the rear wheel. A returning device is provided in the control unit for returning the rear wheel to the neutral position by means of the motor when an abnormal condition is detected in the detectors but at least two of the detectors have the same indication of the steered position of the rear wheel, and for disengaging the clutch to return the rear wheel to the neutral position by virtue of the resilient force of the urging device. The rear wheel is returned to the neutral position without making the steering of the vehicle unstable when the rear wheel steering system is an abnormal condition.
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