Vehicle brake system having adaptive torque control

• US 6,663,197 B2
• Filed: 04/02/2002
• Issued: 12/16/2003
• Est. Priority Date: 04/02/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Joyce, John Patrick
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US10/063,239
• Publication Number:
  US 20030184154A1
• Time in Patent Office: 623 Days
• Field of Search: 303/152, 303/3, 303/20, 303/112, 303/155, 303/13-15, 303/177, 303/199, 701/22, 180/165, 180/65.1, 188/181.T, 188/156, 188/158
• US Class Current: 303/152
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/16 longitudinal
• CPC Class Codes: B60L 2240/26 Vehicle weight
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2250/28 Accelerator pedal thresholds
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 13/66 Electrical control in fluid-pressure brake systems
• CPC Class Codes: B60T 8/00 Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force by changing number of effective brake cylinders in power brake systems B60T17/10
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A vehicle brake system (10) is provided which compensates for brake pedal feel variation so as to provide for enhanced braking feel to the vehicle operator. The brake system (10) includes a brake command input (10), an accelerometer (22) for sensing longitudinal acceleration of the vehicle, and friction brakes (26) and regenerative brakes (29) for generating braking force to be applied to brakes on the vehicle. The vehicle brake system (10) further includes a controller (12) for detecting a brake torque variation as a function of the sensed acceleration and the brake demand signal. The controllers (12) further adjusts a torque command signal to adjust the amount of braking torque generated by the brakes (26) so as to compensate for brake torque variation.

Claims

1. A vehicle brake system comprising:

a brake demand input;

an accelerometer for sensing longitudinal acceleration of a vehicle;

a brake actuator for generating braking force to be applied to one or more

brakes on the vehicle; and

a controller for receiving the brake demand signal and the sensed acceleration and detecting a brake torque variation as a function of the sensed acceleration and brake demand signal, said controller further adjusting a torque command signal to adjust the amount of braking torque generated by the brake actuator so as to compensate for the brake torque variation.

2. The brake system as defined in claim 1, wherein the brake actuator comprises a friction brake actuator.

3. The brake system as defined in claim 2, wherein said brake actuator further comprises a regenerative brake, wherein the amount of braking force is proportioned between the friction brake actuator and the regenerative brake.

4. The brake system as defined in claim 1 further comprising a wheel speed sensor for sensing vehicle wheel speed, wherein the controller calculates a kinetic acceleration of the vehicle as a function of the sensed wheel speed.

5. The brake system as defined in claim 4, wherein the controller calculates acceleration of the vehicle due to brake torque as a function of the sensed acceleration and the calculated kinetic acceleration, and further estimates brake torque as a function of the calculated acceleration.

6. The brake system as defined in claim 5 further comprising calculating an expected aerodynamic induced acceleration, said controller estimating the brake torque further as a function of the expected aerodynamic induced acceleration.

7. The brake system as defined in claim 5, wherein said controller determines a desired brake torque as a function of the brake demand input and determines a torque error as the difference between the desired torque and the estimated brake torque, said controller further modifying the torque command signal to compensate for the torque error.

8. A vehicle brake system comprising:

a brake demand input;

an accelerometer for sensing longitudinal acceleration of a vehicle;

a frictional brake actuator for providing friction braking;

a regenerative brake actuator for providing regenerative braking of the vehicle; and

a controller for receiving the brake demand input and the sensed acceleration and detecting a brake torque variation as a function of the sensed acceleration and the brake demand input, said controller further adjusting a torque command signal to adjust the amount of braking torque generated by the brake friction actuator so as to compensate for the brake torque variation.

9. The brake system as defined in claim 8, wherein said controller controls a proportional amount of friction braking and regenerative braking.

10. The brake system as defined in claim 8 further comprising a wheel speed sensor for sensing vehicle wheel speed, wherein the controller calculates the kinetic acceleration as a function of the sensed wheel speed.

11. The brake system as defined in claim 8, wherein the controller calculates acceleration of the vehicle due to brake torque as a function of the sensed acceleration and the calculated kinematic acceleration, and further estimates brake torque as a function of the calculated acceleration.

12. The brake system as defined in claim 11, wherein the controller further calculates an expected aerodynamic induced acceleration, said controller estimating the brake torque further as a function of the expected aerodynamic induced acceleration.

13. The brake system as defined in claim 11, wherein said controller determines a desired brake torque as a function of the brake demand input and determines a torque error as the difference between the desired torque and the estimated brake torque, said controller further modifying the torque command signal to compensate for the torque error.

14. A method of controlling a brake system in a vehicle to compensate for brake torque variation, said method comprising the steps of:

receiving a brake demand signal;

sensing longitudinal acceleration of a vehicle;

generating braking force to be applied to one or more brakes on the vehicle;

detecting a brake torque variation as a function of the sensed acceleration and brake demand signal; and

adjusting a torque command signal to adjust the amount of braking torque generated so as to compensate for the brake torque variation.

15. The method as defined in claim 14, wherein the step of generating braking force comprises generating braking force applied by a friction brake actuator.

16. The method as defined in claim 15, wherein the step of generating braking force further comprises generating braking force by a regenerative brake.

17. The method as defined in claim 14 further comprising the steps of:

sensing vehicle wheel speed; and

calculating a kinematic acceleration as a function of the sensed wheel speed.

18. The method as defined in claim 14 further comprising the steps of:

calculating acceleration of the vehicle due to brake torque as a function of the sensed acceleration and the calculated kinematic acceleration; and

estimating brake torque as a function of the calculated acceleration.

19. The method as defined in claim 18 further comprising the steps of:

calculating an expected aerodynamic induced acceleration; and

estimating the brake torque further as a function of the expected aerodynamic induced acceleration.

20. The method as defined in claim 18 further comprising the steps of:

determining a desired brake torque as a function of the brake demand input;

determining a torque error as the difference between the desired torque and the estimated brake torque; and

modifying the torque command signal to compensate for the torque error.