| 摘要 |
An auxiliary drive circuit is disclosed for an electric, power assist steering system including an actuatable switching device which, when actuated, provides an auxiliary electrical path between a source of electrical energy and a mechanically actuatable reversing switch assembly for applying electrical power to energize an electric assist motor. The actuatable switching device in the auxiliary drive circuit is electrically connected in parallel to an actuatable switching device in a main drive circuit. A detector circuit monitors the operation of the main drive circuit and the output signal from a torque sensor. Upon detection of applied steering torque greater than a predetermined value and that the main drive circuit is not operating, the detector circuit outputs an electrical signal indicative thereof. A latching element latches the output of the detector circuit to actuate the actuatable switching device in the auxiliary drive circuit. Actuating the actuatable switching device in the auxiliary drive circuit provides an auxiliary connection of the electric assist motor to the source of electrical energy. In one embodiment, the auxiliary drive circuit, when actuated, permits maximum, continuous current flow through the power assist motor. In another embodiment, the auxiliary drive circuit provides a controllable amount of power assist in response to applied steering torque.
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