Control Device of Electric Power Steering Device for Vehicles in Which Steered Wheels Are Driven

• US 20070265751A1
• Filed: 10/11/2005
• Published: 11/15/2007
• Est. Priority Date: 10/14/2004
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tsuchiya, Yoshiaki
• Granted Patent: US 8,352,123 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 5/0466 for returning the steering wheel to neutral position
• CPC Class Codes: B62D 5/0472 for damping vibrations

Abstract

When the steered wheels are driven, there is a problem of the torque steering that the steering is disturbed by the difference in the driving forces between a pair of left and right steered wheels. Before such a problem, there is a problem that, since the vehicle is apt to run straight ahead more strongly as the driving force increases even when a uniform driving torque is given to a pair of steered wheels, a larger force is required to steer the vehicle leftward or rightward by overcoming such a tendency of running straight ahead. In view of the above, the steering assist force is increased according to an increase of the driving torque of the steered wheels in a manner of harmonizing the steering assist force to the magnitude of the steering resistance due to the driving torque of the steered wheels, so as to improve the steering feeling.

Claims

1. A control device of an electric power steering device for vehicles comprising a steering wheel, a pair of steered wheels adapted to be steered by the steering wheel, and a power source for driving the steered wheels, characterized by comprising a calculating device which calculates a target value of a steering assist force to be generated by the electric power steering device so as to be increased according to an increase of the steering torque of the steering wheel with an increase which increases according to an increase of the driving torque of the steered wheels when driving force of the steered wheels is higher than a value which affects steer feeling.

2. A control device according to claim 1, wherein the calculating device is so adapted as to increase the target value of the steering assist force according to an increase of a time-based differential of steering angle of the steering wheel.

3. A control device according to claim 1, wherein the calculating device is so adapted as to calculate a target value of the steering assist force for reversal steering which increases according to an increase of the driving torque of the steered wheels.

4. A controlled device according to claim 3, wherein the calculating device is so adapted as to decrease the target value of the steering assist torque for reversal steering according to an increase of vehicle speed.

5. A control device according to claim 4, wherein the calculating device is so adapted as to make the target value of the steering assist torque for reversal steering to be the largest when the steering angle of the steering wheel is medium.

6. A control device according to claim 1, wherein the calculating device is so adapted as to decrease the target value of the steering assist force according to an increase of a time-based differential of the steering angle of the steering wheel by a rate which increases according to an increase of vehicle speed.

7. A control device according to claim 1, wherein the calculating device is so adapted as to decrease the target value of the steering assist force according to an increase of vehicle speed.

8. A control device according to claim 3, wherein the calculating device is so adapted as to increase the target value of the steering assist force for reversal steering according to an increase of the steering angle of the steering wheel in a region where the steering angle of the steering wheel is smaller than a determined value.