Motor-driven power steering control apparatus

• US 6,816,765 B2
• Filed: 03/07/2003
• Issued: 11/09/2004
• Est. Priority Date: 09/30/2002
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kifuku, Takayuki, Yamamoto, Munenori
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US10/379,341
• Publication Number:
  US 20040064228A1
• Time in Patent Office: 613 Days
• Field of Search: 701/41, 701/42, 180/404, 180/407, 180/422, 180/443, 180/446
• US Class Current: 701/41
• CPC Class Codes: B62D 5/0457 characterised by control features of the drive means as such
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input

Abstract

A motor-driven power steering control apparatus for determining pertinent timings for starting/stopping application of steering assist torque includes a motor for applying an assist torque, a sensor for detecting a steering torque, a driving unit for operating the motor in dependence on a detected steering torque, a command unit for commanding starting and stopping of operation of the motor, and a motor operation decision unit. When stopping of operation of the motor is commanded by the command unit, the motor operation decision unit stops driving operation of the motor while commanding the driving unit to stop application of the steering assist torque when a state in which a steering torque is not greater than a predetermined value for stoppage has continued for a predetermined time period.

Claims

1. A motor-driven power steering control apparatus for a motor vehicle, comprising:

an electric motor for applying a steering assist torque to a steering system of said motor vehicle;

steering torque detecting means for detecting a steering torque of said steering system;

motor driving means for operating said electric motor in dependence on a detected value of said steering torque;

motor operation command means for commanding starting and stopping of driving operation of said electric motor; and

motor operation decision means for deciding starting and stopping of the driving operation of said electric motor on the basis of a command issued by said motor operation command means,

wherein said motor operation decision means is so arranged that when stopping of the driving operation of said electric motor is commanded by said motor operation command means, said motor operation decision means stops the driving operation of said electric motor while commanding said motor driving means to stop application of said steering assist torque, provided that a state in which a detected value of said steering torque is not greater than a value predetermined for stopping the driving operation of said electric motor has continued for a time period predetermined for the stoppage.

6. A motor-driven power steering control apparatus according to claim 1,

wherein said time period predetermined for the stoppage is set to a time ranging from 0.01 second to 1 second.

7. A motor-driven power steering control apparatus according to claim 1,

wherein said predetermined value for the stoppage is set to a value corresponding to a steering torque of 1 Nm.

8. A motor-driven power steering control apparatus according to claim 1,

wherein said motor operation decision means is so arranged as to stop driving operation of said electric motor while commanding said motor driving means to stop application of said steering assist torque at a time point at which a predetermined operation time has lapsed since issuance of a command for stopping the driving operation of said electric motor by said motor operation command means.

9. A motor-driven power steering control apparatus according to claim 8,

wherein said predetermined operation time is set to a value which is not greater than 10 seconds.

10. A motor-driven power steering control apparatus according to claim 1,

wherein said motor operation decision means is so arranged as to start driving operation of said electric motor while commanding said motor driving means to start application of said steering assist torque at a time point at which a command for starting operation of said electric motor is issued by said motor operation command means, provided that a state in which the detected value of said steering torque is not greater than a value predetermined for starting operation of said electric motor has continued for a time period predetermined for starting the motor operation.

2. A motor-driven power steering control apparatus for a motor vehicle, comprising:

an electric motor for applying a steering assist torque to a steering system of said motor vehicle;

steering torque detecting means for detecting a steering torque of said steering system;

motor driving means for operating said electric motor by controlling a state quantity corresponding to output of said electric motor in dependence on a detected value of said steering torque;

motor operation command means for commanding starting and stopping of driving operation of said electric motor; and

motor operation decision means for deciding starting and stopping of the driving operation of said electric motor on the basis of a command issued by said motor operation command means,

wherein said motor operation decision means is so arranged that when stopping of the driving operation of said electric motor is commanded by said motor operation command means, said motor operation decision means stops the driving operation of said electric motor while commanding said motor driving means to stop application of said steering assist torque, provided that a state in which a state quantity of said electric motor is not greater than a value predetermined for stopping the driving operation of said electric motor has continued for a time period predetermined for the stoppage.

3. A motor-driven power steering control apparatus according to claim 2,

wherein said motor operation decision means is so designed as to make said decision on the basis of a current value of said driving motor adopted as said state quantity.

4. A motor-driven power steering control apparatus according to claim 2,

wherein said motor operation decision means is so designed as to make said decision on the basis of a motor-applied voltage value adopted as said state quantity.

5. A motor-driven power steering control apparatus according to claim 2, further comprising:

inter-terminal voltage detecting means for detecting an inter-terminal voltage value of said electric motor,

wherein said motor operation decision means is so arranged as to make said decision on the basis of said inter-terminal voltage value adopted as said state quantity.

11. A motor-driven power steering control apparatus for a motor vehicle, comprising:

an electric motor for applying a steering assist torque to a steering system of said motor vehicle;

a steering torque detecting unit that detects a steering torque of said steering system;

a motor driving unit that operates said electric motor in dependence on a detected value of said steering torque;

a motor operation command unit to start and stop a drive operation of said electric motor; and

a motor operation decision unit that decides a start and stop of the drive operation of said electric motor on the basis of a command issued by said motor operation command unit,

wherein, application of said steering assist torque is stopped when a state where a detected value of said steering torque is less than or equal to a predetermined stopping value of the driving operation of said electric motor, continues for a predetermined stop time period.

16. A motor-driven power steering control apparatus according to claim 11,

wherein said predetermined stop time period is set to a time ranging from 0.01 second to 1 second.

17. A motor-driven power steering control apparatus according to claim 11,

wherein said predetermined stop time period is set to a value corresponding to a steering torque of 1 Nm.

18. A motor-driven power steering control apparatus according to claim 11,

wherein application of said steering assist torque is stopped at a time point at which a predetermined operation time has lapsed since issuance of a command for stopping a driving operation of said electric motor by said motor operation command unit.

19. A motor-driven power steering control apparatus according to claim 18,

wherein said predetermined operation time is set to a value which is not greater than 10 seconds.

20. A motor-driven power steering control apparatus according to claim 11,

wherein application of said steering assist torque is started at a time point at which a command for a starting operation of said electric motor is issued by said motor operation command unit, and where a state in which the detected value of said steering torque is less than or equal to a predetermined starting value of said electric motor, has continued for a time period predetermined for starting the motor operation.

12. A motor-driven power steering control apparatus for a motor vehicle, comprising:

an electric motor for applying a steering assist torque to a steering system of said motor vehicle;

a steering torque detecting unit that detects a steering torque of said steering system;

a motor driving unit that operates said electric motor in dependence on a detected value of said steering torque;

a motor operation command unit to start and stop a drive operation of said electric motor; and

a motor operation decision unit that decides a start and stop of the drive operation of said electric motor on the basis of a command issued by said motor operation command unit,

wherein, application of said steering assist torque is stopped when a state where a state quantity of said electric motor is less than or equal to a predetermined stopping value of the driving operation of said electric motor, continues for a predetermined stop time period.

13. A motor-driven power steering control apparatus according to claim 12,

wherein said motor operation decision unit is so designed as to make said decision on the basis of a current value of said driving motor adopted as said state quantity.

14. A motor-driven power steering control apparatus according to claim 12,

wherein said motor operation decision unit is so designed as to make said decision on the basis of a motor-applied voltage value adopted as said state quantity.

15. A motor-driven power steering control apparatus according to claim 12, further comprising:

an inter-terminal voltage detecting unit for detecting an inter-terminal voltage value of said electric motor,

wherein said motor operation decision unit is so arranged as to make said decision on the basis of said inter-terminal voltage value adopted as said state quantity.