Brake system and method of control with air gap estimation

Patent metadata

Field	Value
Publication number	US-10422396-B2
Application number	US-201715484572-A
Country	US
Kind code	B2
Filing date	Apr 11, 2017
Priority date	Jun 3, 2016
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

A brake system and a method of controlling a brake system. The method may include indirectly estimating an air gap between a brake friction member and a brake pad assembly based on a position signal from a position sensor that detects cycling of the friction brake and a further signal indicative of an amount of brake force used to engage the brake pad assembly with the brake friction member. The air gap may be adjusted when an estimated air gap differs from a desired air gap.

First claim

What is claimed is:

1. A method of controlling a brake system comprising:
cycling a friction brake;
indirectly estimating an air gap between a brake friction member and a brake pad assembly based on a position signal from a position sensor that detects the cycling of the friction brake and a further signal indicative of an amount of brake three used to engage the brake pad assembly with the brake friction member, wherein indirectly estimating the air gap includes adjusting the position signal to compensate for drift of the position signal based on the further signal, wherein the further signal is indicative of a pressure in an actuator during the cycling of the friction brake; and
adjusting the air gap when the indirectly estimated air gap differs from a desired air gap.

2. The method of claim 1 wherein the position sensor detects rotation of an operating shaft during the cycling of the friction brake.

3. The method of claim 1 wherein cycling the friction brake further comprises actuating the brake pad assembly from a retracted position in which the brake pad assembly is spaced apart from the brake friction member into engagement with the brake friction member and releasing the brake pad assembly such that the brake pad assembly disengages the brake friction member.

4. The method of claim 3 wherein adjusting the air gap further comprises operating an adjustment motor to change the retracted position such that the brake pad assembly is disposed closer to the brake friction member, or wherein the method further comprises adjusting the air gap when the indirectly estimated air gap is less than the desired air gap by operating the adjustment motor to change the retracted position such that the brake pad assembly is disposed further from the brake friction member, or wherein adjusting the air gap occurs during release of the brake pad assembly.

5. The method of claim 1 further comprising not adjusting the air gap when the indirectly estimated air gap is within an allowable range to the desired air gap.

6. The method of claim 1 wherein the further signal is indicative of a maximum pressure in the actuator during the cycling of the friction brake.

7. The method of claim 1 wherein the step of indirectly estimating the air gap includes determining a predetermined relationship between the position signal, the further signal, and the air gap and determining the estimate of the air gap from the position signal, the further signal, and the predetermined relationship.

8. The method of claim 7 wherein the predetermined relationship is defined by at least one of a map, a look up table, an algorithm and a database.

9. A method of controlling a brake system comprising:
cycling a friction brake by actuating a brake pad assembly from a retracted position into engagement with a brake friction member and releasing the brake pad assembly such that the brake pad assembly disengages the brake friction member and moves toward the retracted position;
indirectly estimating an air gap between the brake friction member and the brake pad assembly based on a position signal from a position sensor that is indicative of actuation of a brake pedal and on a further signal indicative of an amount of brake force used to engage the brake pad assembly with the brake friction member, wherein indirectly estimating the air gap includes adjusting the position signal to compensate for drift of the position signal based on the further signal, wherein the further signal is indicative of a pressure in an actuator during the cycling of the friction brake; and
adjusting the air gap when the indirectly estimated air gap differs from a desired air gap.

10. The method of claim 9 wherein indirectly estimating the air gap includes clipping the position signal from the position sensor by determining a first inflection point and a second inflection point of the position signal and clipping the position signal to a first time value that corresponds to the first inflection point and to a second time value that corresponds to the second inflection point.

11. The method of claim 10 wherein the first inflection point is indicative of engagement of the brake pad assembly with the brake friction member or wherein the second inflection point is indicative of disengagement of the brake pad assembly from the brake friction member.

12. The method of claim 10 wherein adjusting the position signal to compensate for the drift occurs after clipping the position signal.

13. The method of claim 12 wherein indirectly estimating the air gap further comprises making an error adjustment by determining a centroid of an error area disposed between the first inflection point and the second inflection point and adjusting the position signal based on the centroid of the error area.

14. The method of claim 13 wherein making the error adjustment includes adjusting the position signal to a constant value between the first inflection point and the second inflection point.

15. The method of claim 13 wherein making the error adjustment is based on fuzzy logic.

16. The method of claim 9 wherein the further signal is indicative of a maximum pressure in the actuator during the cycling of the friction brake.

17. A brake system comprising:
a brake friction member;
a brake pad assembly configured to move between a retracted position in Which the brake pad assembly does not engage the brake friction member and an extended position in which the brake pad assembly engages the brake friction member;
an actuator subsystem that includes an operating shaft that rotates when the brake pad assembly moves between the retracted position and the extended position;
a position sensor that detects rotation of the operating shaft; and
a controller configured to estimate an air gap between the brake pad assembly and the brake friction member based on a position signal from the position sensor and a signal indicative of an amount of brake force used to engage the brake pad assembly with the brake friction member, wherein estimating the air gap includes adjusting, by the controller, the position signal to compensate for drift of the position signal based on a pressure in the actuator subsystem during cycling of the brake pad assembly.

18. The brake system of claim 17 wherein the position signal from the position sensor is obtained when the brake pad assembly moves from the retracted position to the extended position and back to the retracted position.

19. The brake system of claim 17 wherein the brake system further comprises an adjustment motor, wherein the adjustment motor moves the brake pad assembly closer to the brake friction member to reduce the air gap when the air gap estimated by the controller exceeds a desired air gap, or the adjustment motor moves the brake pad assembly further from the brake friction member to increase the air gap when the air gap estimated by the controller that is based on the position signal from the position sensor does not exceed the desired air gap, or wherein the adjustment motor adjusts the air gap when the brake pad assembly moves from the extended position toward the retracted position and the adjustment motor does not move the brake pad assembly from the retracted position to the extended position.

Assignees

• Meritor Heavy Vehicle Braking Systems Uk Ltd

Inventors

• Yao Yixin
• Narula Prashant

Classifications

• B60T17/22 Primary

  Devices for monitoring or checking brake systems; Signal devices · CPC title

• F16D2066/003

  Position, angle or speed · CPC title

• F16D2065/386

  driven electrically · CPC title

• F16D65/66 Primary

  with screw-thread and nut · CPC title

• B60T13/741

  acting on an ultimate actuator · CPC title