Power steering device
An electric power steering apparatus provides stable steering assist force by positively precluding actuation of an electric motor while it is rotating in a reverse direction, so as to prevent demagnetization of the electric motor. A motor reverse rotation detecting means detects whether or not the electric motor is rotating in the reverse direction and a motor actuation control actuates the electric motor when a condition for actuating the electric motor is fulfilled and on condition that the electric motor is not rotating in the reverse direction.
1. A power steering apparatus, comprising:
a steering motor which rotates in a normal direction in use;
a pump which is driven by the steering motor and provides hydraulic pressure generated thereby to a steering mechanism as a steering assist force;
motor reverse rotation detecting means for detecting whether or not the steering motor is rotating in a direction reverse of the normal direction; and
motor actuation control means for actuating the steering motor to rotate only in the normal direction and only when, in combination, a predetermined first condition for actuating the steering motor to rotate in the normal direction is fulfilled and a second condition that reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means is fulfilled.
2. The power steering apparatus according to claim 1 , wherein detection of reverse rotation of the steering motor by the motor reverse rotation detecting means is effected within an initial check period.
3. The power steering apparatus according to claim 1 , wherein when the predetermined first condition for actuating the steering motor is fulfilled, the motor actuation control means actuates the steering motor after expiration of a predetermined standby period following a determination that reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means.
4. The power steering apparatus according to claim 3 , wherein a time for detection by the motor reverse rotation detecting means and the predetermined standby period are set so that the predetermined standby period expires within the initial check period.
5. The power steering apparatus according to claim 3 , wherein the predetermined standby period is set so that the duration thereof is sufficiently long for the steering motor to come to a halt when the steering motor is coasting at a rotation speed lower than a predetermined rotation speed.
6. The power steering apparatus according to claim 3 , further comprising motor normal rotation detecting means for detecting whether or not the steering motor is rotating in the normal direction,
wherein, in a case where reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means, the motor actuation control means immediately actuates the steering motor upon detection of normal rotation of the steering motor by the motor normal rotation detecting means, and only in a case where neither normal nor reverse rotation of the steering motor is detected, the motor actuation control means actuates the steering motor after expiration of the standby period.
7. The power steering apparatus according to claim 1 , wherein the predetermined condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
8. The power steering apparatus according to claim 1 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
9. The power steering apparatus according to claim 2 , wherein when the predetermined first condition for actuating the steering motor is fulfilled, the motor actuation control means actuates the steering motor after expiration of a predetermined standby period following a determination that reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means.
10. The power steering apparatus according to claim 4 , wherein the predetermined standby period is set so that the duration thereof is sufficiently long for the steering motor to come to a halt when the steering motor is coasting at a rotation speed lower than a predetermined rotation speed.
11. The power steering apparatus according to claim 4 , further comprising motor normal rotation detecting means for detecting whether or not the steering motor is rotating in the normal direction,
wherein in a case where reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means, the motor actuation control means immediately actuates the steering motor upon detection of normal rotation of the steering motor by the motor normal rotation detecting means, and only in a case where neither normal nor reverse rotation of the steering motor is detected, the motor actuation control means actuates the steering motor after expiration of the standby period.
12. The power steering apparatus according to claim 5 , further comprising motor normal rotation detecting means for detecting whether or not the steering motor is rotating in the normal direction,
wherein, in a case where reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means, the motor actuation control means immediately actuates the steering motor upon detection of normal rotation of the steering motor by the motor normal rotation detecting means, and only in a case where neither normal nor reverse rotation of the steering motor is detected, the motor actuation control means actuates the steering motor after expiration of the standby period.
13. A power steering apparatus according to claim 2 , wherein the predetermined first condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
14. A power steering apparatus according to claim 3 , wherein the predetermined first condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
15. A power steering apparatus according to claim 4 , wherein the predetermined first condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
16. A power steering apparatus according to claim 5 , wherein the predetermined first condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
17. A power steering apparatus according to claim 6 , wherein the predetermined first condition for actuating the steering motor includes that a steering speed is equal to or more than a predetermined level.
18. The power steering apparatus according to claim 2 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
19. The power steering apparatus according to claim 3 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
20. The power steering apparatus according to claim 4 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the lectric steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
21. The power steering apparatus according to claim 5 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
22. The power steering apparatus according to claim 6 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
23. The power steering apparatus according to claim 7 , wherein the predetermined first condition for actuating the steering motor includes detection of recovery of the steering motor from a state of failure after stoppage thereof caused by a fail-safe function.
24. The power steering apparatus according to claim 1 , wherein the motor actuation control means positively precludes actuation of the steering motor while it is rotating in a reverse direction.
25. The power steering apparatus according to claim 1 , wherein the steering motor is of a type which is susceptible to demagnetization if actuated while rotating in the direction reverse of the normal direction.
26. A power steering apparatus, comprising:
a steering motor which rotates in a normal direction in use;
a pump which is driven by the steering motor and provides hydraulic pressure generated thereby to a steering mechanism as a steering assist force;
motor reverse rotation detecting means for detecting whether or not the steering motor is rotating in a direction reverse of the normal direction; and
motor actuation control means for actuating the steering motor to rotate in the normal direction when, in combination, a predetermined first condition for actuating the steering motor to rotate in the normal direction is fulfilled and a second condition that reverse rotation of the steering motor is not detected by the motor reverse rotation detecting means is fulfilled,
wherein the motor actuation control means positively precludes actuation of the steering motor while it is rotating in the reverse direction.