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Torque sensing power steering device with abnormality detection, dead zone detection and power assist motor inhibition

  • US 5,720,361 A
  • Filed: 10/12/1995
  • Issued: 02/24/1998
  • Est. Priority Date: 10/12/1994
  • Status: Expired due to Term
First Claim
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1. An electric power steering apparatus in which a motor current target value of a steering force assisting motor is determined on the basis of a torque detected by a torque sensor, a drive of said motor is controlled using the motor current target value as a target value of an automatic control, and using a driving current of said motor as a feedback value of the automatic control, and, when the detected torque is within a predetermined range, said motor is inhibited from being driven in a direction opposite to the detected torque, said apparatus comprising:

  • non-drive detecting means for detecting that the motor current target value is zero; and

    drive inhibition holding means for holding a motor drive inhibition state where said motor is inhibited from being driven in the direction opposite to the detected torque, until said non-drive detecting means detects that the motor current target value is zero;

    dead zone detecting means for detecting a dead zone of the detected torque where the motor current target value is to be zero;

    abnormal state detecting means for detecting a state where the detected torque is outside the dead zone and the direction in which said motor is to be driven in accordance with the motor current target value is opposite to the direction of the detected torque; and

    drive inhibiting means for, when said abnormal state detecting means detects the abnormal state, inhibiting said motor from being driven.

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