Electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-9308935-B2
Application number	US-201414553360-A
Country	US
Kind code	B2
Filing date	Nov 25, 2014
Priority date	Nov 27, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Provided is an electric power steering apparatus capable of performing steering of a steering wheel with a comfortable steering feeling while stabilizing a vehicle behavior even in a vicinity of a steering neutral position. A first electric power steering apparatus includes a steering torque sensor for detecting a steering torque inputted by a driver, a steering angle sensor for detecting a steering angle of a steering wheel, a steering assist motor for applying a steering assist force to the steering wheel, and a drive control unit for performing drive control of the steering assist motor based on the steering torque and the steering angle. The drive control unit performs drive control of the steering assist motor based on the steering angle detected by the steering angle sensor and hysteresis characteristics related to a steering reaction force associated with a change of the steering angle.

First claim

What is claimed is:

1. An electric power steering apparatus comprising:
a steering member which is configured to be operated by a driver when turning a turning wheel of a vehicle;
a steering torque detector for detecting a steering torque which is inputted by the driver to a steering shaft attached to the steering member based on torsion information of a torsion bar portion constituting at least a part of the steering shaft;
a steering angle detector for detecting a steering angle of the steering member;
a steering assist motor for applying a steering assist force to the steering member via the steering shaft in order to adjust the steering torque inputted by the driver; and
a drive control unit for performing drive control of the steering assist motor based on at least the steering torque detected by the steering torque detector and the steering angle detected by the steering angle detector,
wherein the drive control unit includes a steering reaction force characteristics storage unit for storing hysteresis characteristics related to a steering reaction force which is generated by driving the steering assist motor and is associated with a change of the steering angle in a case where the steering angle is increased or decreased by steering the steering member, and performs drive control of the steering assist motor based on the steering angle and the hysteresis characteristics stored in the steering reaction force characteristics storage unit, and
wherein the steering angle detector is provided on a side of the turning wheel relative to a position where the steering torque detector is provided on the steering shaft.

2. An electric power steering apparatus comprising:
a steering member which is configured to be operated by a driver when turning a turning wheel of a vehicle;
a steering torque detector for detecting a steering torque which is inputted by the driver to a steering shaft attached to the steering member based on torsion information of a torsion bar portion constituting at least a part of the steering shaft;
a steering angle detector for detecting a steering angle of the steering member;
a steering assist motor for applying a steering assist force to the steering member via the steering shaft in order to adjust the steering torque inputted by the driver; and
a drive control unit for performing drive control of the steering assist motor based on at least the steering torque detected by the steering torque detector and the steering angle detected by the steering angle detector,
wherein the steering angle detector is provided on a side of the steering member relative to a position where the steering torque detector is provided on the steering shaft
wherein the electric power steering apparatus further comprises a steering information processing unit, which estimates a torsion angle of the steering shaft based on a detection result by the steering torque detector, and calculates a correction amount of the steering angle for compensating a torsion amount of the steering shaft based on the estimated torsion angle of the steering shaft, and then calculates a steering angle after a correction for compensating the torsion amount of the steering shaft based on the steering angle detected by the steering angle detector and the calculated correction amount of the steering angle, and
wherein the drive control unit includes a steering reaction force characteristics storage unit for storing hysteresis characteristics related to a steering reaction force which is generated by driving the steering assist motor and is associated with a change of the steering angle after the correction in a case where the steering angle is increased or decreased by steering the steering member, and performs drive control of the steering assist motor based on the steering angle after the correction and the hysteresis characteristics stored in the steering reaction force characteristics storage unit.

3. The electric power steering apparatus according to claim 1 ,
wherein in the hysteresis characteristics, the steering reaction force associated with a case where the steering angle is in a neutral position is set to a value other than zero.

4. The electric power steering apparatus according to claim 1 ,
wherein a torsional rigidity of the torsion bar portion is set to high rigidity exceeding a reference threshold value for maintaining stable running of the vehicle.

5. The electric power steering apparatus according to claim 1 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

6. The electric power steering apparatus according to claim 2 ,
wherein in the hysteresis characteristics, the steering reaction force associated with a case where the steering angle is in a neutral position is set to a value other than zero.

7. The electric power steering apparatus according to claim 2 ,
wherein a torsional rigidity of the torsion bar portion is set to high rigidity exceeding a reference threshold value for maintaining stable running of the vehicle.

8. The electric power steering apparatus according to claim 3 ,
wherein a torsional rigidity of the torsion bar portion is set to high rigidity exceeding a reference threshold value for maintaining stable running of the vehicle.

9. The electric power steering apparatus according to claim 6 ,
wherein a torsional rigidity of the torsion bar portion is set to high rigidity exceeding a reference threshold value for maintaining stable running of the vehicle.

10. The electric power steering apparatus according to claim 2 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

11. The electric power steering apparatus according to claim 3 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

12. The electric power steering apparatus according to claim 4 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

13. The electric power steering apparatus according to claim 6 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

14. The electric power steering apparatus according to claim 7 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

15. The electric power steering apparatus according to claim 8 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque inputted by the driver without touching the torsion bar portion.

16. The electric power steering apparatus according to claim 9 ,
wherein the steering torque detector is composed of a magnetostrictive torque sensor which is provided on the torsion bar portion to detect the steering torque

Assignees

• Honda Motor Co Ltd

Inventors

• Ohno Satoshi
• Oniwa Yoshihiro
• Yoneda Atsuhiko
• Shimizu Yasuo

Classifications

• B62D15/0215

  by measuring on the steering column · CPC title

• B62D5/0466 Primary

  for returning the steering wheel to neutral position · CPC title

• B62D6/008

  Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications · CPC title