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US 10,093,349 B2Granted
Monitoring of an electric motor in an electric power steering assembly
AssigneeTRW Automotive U.S. LLC
InventorsChristopher Woodruff, Timothy Sworn
Life of this patent
Estimating the term…
Abstract
A magnet is fixed to an output shaft of a motor. The output shaft is rotated such that a magnetic field emitted by the magnet also rotates. A voltage pulse is generated from a passive sensor when the magnetic field rotates past the passive sensor. The voltage pulse is generated using a Wiegand wire. An active sensor is activated, from an unpowered state, in response to the voltage pulse. The active sensor detects a position of the magnet that correlates to a position of the output shaft.
Claims17
A method of monitoring an electric motor of a vehicle electric power steering assembly comprising the steps of:
- fixing a magnet to an output shaft of the motor;
- rotating the output shaft such that a magnetic field emitted by the magnet also rotates;
- generating a voltage pulse from a passive sensor when the magnetic field rotates past the passive sensor, wherein the voltage pulse is generated using a Wiegand wire;
- activating an active sensor, from an unpowered state, in response to the voltage pulse, wherein the active sensor detects a position of the magnet that correlates to a position of the output shaft;
- powering the active sensor with a power supply to active the active sensor, wherein the power supply is other than the passive sensor;
- and
- determining a direction of rotation for the output shaft as a function of a hysteresis threshold position and position pulses generated by the active sensor;
- wherein a difference between first and second position pulses being greater than the hysteresis threshold position indicates the output shaft is continuing to rotate in a first direction and the difference being less than the hysteresis threshold position indicates the output shaft is rotating in a second direction opposite the first direction.
5 more elements
A vehicle electric power steering assembly comprising:
- a motor having an output shaft;
- a magnet fixed to the output shaft and emitting a magnetic field, wherein the magnetic field rotates when the motor rotates;
- a passive sensor having a Wiegand wire and generating a voltage pulse in response to rotation of the magnetic field;
- an active sensor detecting a position of the magnet, wherein the active sensor is activated, from an unpowered state, by the voltage pulse and the position of the magnet correlates to a position of the output shaft;
- and
- a power supply powering the active sensor when the active sensor is activated, wherein the power supply is other than the passive sensor;
- wherein a direction of rotation for the output shaft is determined as a function of a hysteresis threshold position and position pulses generated by the active sensor;
- and
- wherein a difference between first and second position pulses being greater than the hysteresis threshold position indicates the output shaft is continuing to rotate in a first direction and the difference being less than the hysteresis threshold indicates the output shaft is rotating in a second direction opposite the first direction.
6 more elements
A vehicle electric power steering assembly comprising:
- a motor having an output shaft;
- a magnet fixed to and rotating with the output shaft, wherein the magnet emits a magnetic field and poles of the magnet are perpendicular to a rotational drive axis of the output shaft;
- a passive sensor having a Wiegand wire and generating a voltage pulse in response to rotation of the magnetic field;
- an active sensor detecting a position of the magnet, wherein the active sensor is activated, from an unpowered state, in response to the voltage pulse, when the voltage pulse exceeds a minimum voltage pulse, and the position of the magnet correlates to a position of the output shaft;
- a power supply powering the active sensor when the active sensor is activated, wherein the power supply is not the passive sensor;
- and
- a memory unit, wherein a last voltage pulse from the passive sensor is stored in the memory unit and a count of rotations of the output shaft is determined as a function of the last voltage pulse, a current voltage pulse generated by the passive sensor, and a current output of the active sensor;
- and
- a controller, wherein the controller determines a direction of rotation for the output shaft as a function of a hysteresis threshold position and position pulses generated by the active sensor;
- wherein a direction of rotation for the output shaft is determined as a function of a hysteresis threshold position and position pulses generated by the active sensor;
- and
- wherein a difference between first and second position pulses being greater than the hysteresis threshold position indicates the output shaft is continuing to rotate in a first direction and the difference being less than the hysteresis threshold indicates the output shaft is rotating in a second direction opposite the first direction.
9 more elements
Dependencies are inferred from the claim text.