Power steering apparatus and rotary detector used therefor

• US 5,076,381 A
• Filed: 07/10/1989
• Issued: 12/31/1991
• Est. Priority Date: 07/11/1988
• Status: Expired due to Term

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Matsuoka, Hirofumi, Daido, Toshihiko, Tabuse, Hidetoshi
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): Bompey, Mitchell
• Application Number:
  US07/377,385
• Time in Patent Office: 904 Days
• Field of Search: 180/79.1, 180/141, 180/142, 364/424.01, 364/424.05, 74/388 PS
• US Class Current: 180/446
• CPC Class Codes: B62D 5/0436 the clutch being a controlled emergency clutch, e.g. for disconnecting at motor break-down
• CPC Class Codes: B62D 5/0466 for returning the steering wheel to neutral position

Abstract

An electric power steering apparatus of the invention is provided with a rotary detector for detecting a rotational position of a motor, a vehicle speed sensor for detecting a vehicle speed, a torque sensor for detecting a steering torque, a calculating means for calculating angular velocity of aforesaid motor on the basis of aforesaid rotational position, and a target angular velocity setting means, wherein flow quantity of electric current to a motor for assisting steering force is made larger, when the steering torque is within a dead zone, correspondingly to the increase of the deviation on the basis of the deviation between the target angular velocity and the calculated angular velocity, thereby stabilized steering feeling in the vicinity of the steering angle middle point at the time of returning the steering wheel steered by mostly using the steering torque being in the dead zone.

And this power steering apparatus is capable of fully following up the rotation of the steering wheel as well as preventing the extreme returning of the steering wheel at the time of returning control, by subtracting subtractor current which is made small when both the steering torque and angular velocity are large, and made large when the steering torque is small and the angular velocity is large, from the driving current.

Claims

1. A power steering apparatus comprising,

a steering mechanism for converting a rotation of a steering wheel into right and left directional movement for steering a vehicle;

a steering position detecting means for detecting a steering position of said steering mechanism;

a torque sensor for detecting a steering torque exerted on said steering wheel;

a motor for assisting steering force;

a setting means for setting a driving current of said motor corresponding to the detected steering torque;

an angular velocity detecting means for detecting an angular velocity of said steering mechanism on the basis of said steering position;

an electric current setting means for setting a first current correspondingly to the detected angle velocity and steering torque;

a subtracting means for subtracting said first current from said driving current;

said electric current setting means increasing said first current correspondingly to the increase of said angular velocity, and decreasing the increasing rate of said first current correspondingly to the increase of said steering torque; and

said motor being driven by the subtracted result of said subtracting means.

2. A power steering apparatus as set forth in claim 1, wherein said electric current setting means increases said first current correspondingly to the increase of said angle velocity.

3. A power steering apparatus as set forth in claim 2, wherein said electric current setting means decreases the increasing rate of said first current correspondingly to the increase of said steering torque.

4. A power steering apparatus as set forth in claim 1, further comprising a vehicle speed detecting means for detecting a speed of said vehicle,

said electric current setting means increasing the increasing rate of said first current correspondingly to the detected vehicle speed.

5. A power steering apparatus as set forth in claim 1, wherein said steering position detecting means determines said steering position by the detecting of a rotary position of said motor.

6. A power steering apparatus comprising,

a steering mechanism for converting a rotation of a steering wheel to movement of right-left direction for steering a vehicle;

a steering angle detecting means for detecting a steering angle of said steering mechanism;

a torque sensor for detecting a steering torque exerted on said steering wheel;

a motor for assisting steering force driven by driving current corresponding to the detected steering torque;

an angular velocity calculating means for calculating an angular velocity of said steering mechanism on the basis of the detected steering angle;

an angular velocity setting means for setting the target angular velocity on the basis of the detected steering angle and vehicle speed;

a deviation calculating means for calculating a deviation between the set target angular velocity and calculated angular velocity; and

an electric current control means for controlling said driving current on the basis of the calculated result of said deviation calculating means, when the detected steering torque is within a predetermined zone.

7. A power steering apparatus as set forth in claim 6, wherein said angle velocity setting means makes the increasing rate of the target angle velocity smaller correspondingly to the increase of the vehicle speed.

8. A power steering apparatus as set forth in claim 6, wherein said angle velocity setting means makes the target angle velocity larger correspondingly to the increase of said steering angle.

9. A power steering apparatus as set forth in claim 6, wherein said electric current control means generates the driving current which becomes larger as said calculated result becomes larger.

10. A power steering apparatus as set forth in claim 6 further comprising,

an electric current setting means for setting a first electric current correspondingly to the detected angle velocity and steering torque;

and

a subtracting means for subtracting said first current from said driving current.

11. A power steering apparatus comprising,

a steering mechanism for converting a rotation of a steering wheel into right and left directional movement for steering a vehicle;

a steering position detecting means for detecting a steering position of said steering mechanism;

a torque sensor for detecting a steering torque exerted on said steering wheel;

a motor for assisting steering force driven by driving current corresponding to the detected steering torque;

an angular velocity detecting means for detecting an angular velocity of said steering mechanism on the basis of said steering position;

an electric current setting means for setting a first current correspondingly to the detected angular velocity and steering torque, wherein said electric current setting means increases said first current correspondingly to the increase of said angular velocity, and wherein said electric current setting means decreases the increasing rate of said first current correspondingly to the increase of said steering torque; and

a subtracting means for subtracting said first current from said driving current.

12. A power steering apparatus comprising:

a steering mechanism for converting a rotation of a steering wheel into right and left directional movement for steering a vehicle;

a steering position detecting means for detecting a steering position of said steering mechanism;

a torque sensor for detecting a steering torque exerted on said steering wheel;

a motor for assisting steering force, the motor being driven by a driving current corresponding to the detected steering torque;

an angular velocity detecting means for detecting an angular velocity of said steering wheel on the basis of said steering position;

an electric current setting means for setting a first current corresponding to said detected angular velocity and said steering torque, wherein said first current increases in response to an increase of said angular velocity, and wherein a rate of increase of said first current decreases in response to an increase of said torque; and

current modifying means for modifying said driving current in response to said first current.