Four-wheel steering system with steering motor short circuit control

摘要

A four-wheel steering system on an automobile has front road wheels steerable by a steering wheel and rear road wheels steerable by an electric motor and normally biased to a neutral steering position by a spring. The electric motor is energized by a motor driver to steer the rear road wheels through an angle depending on running conditions of the automobile. The electric motor has a winding and two sets of brushes or connecting terminals connected to opposite terminals of the winding. One of the two sets of connecting terminals is connected to the motor driver. The other of the two sets of connecting terminals is connected to a short-circuiting circuit parallel to the motor driver. In the event of a failure, a controller controls the short-circuiting circuit to short-circuit the winding of the motor through the other set of connecting terminals. The short-circuiting circuit comprises a plurality of relays having respective contacts connected in series between the connecting terminals of the other set. The motor driver can also short-circuit the winding of the motor through the one set of connecting terminals in the event of a failure.