Controller for Electromechanical Braking System with Running Clearance Adjustment and Method

• US 20080283346A1
• Filed: 11/15/2006
• Published: 11/20/2008
• Est. Priority Date: 11/30/2005
• Status: Active Grant

• Current Assignee: Goodrich Corporation (Rtx Corporation)
• Original Assignee: Goodrich Corporation (Rtx Corporation)
• Inventors: Ralea, Mihai
• Granted Patent: US 8,177,308 B2
• Time in Patent Office: Days
• US Class Current: 188/156
• CPC Class Codes: B60T 13/741 acting on an ultimate actuator
• 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: B60T 8/1703 for aircrafts
• CPC Class Codes: F16D 2065/386 driven electrically
• CPC Class Codes: F16D 2066/003 Position, angle or speed
• CPC Class Codes: F16D 2066/005 Force, torque, stress or strain
• CPC Class Codes: F16D 2066/006 without direct measurement of the quantity monitored, e.g. wear or temperature calculated form force and duration of braking
• CPC Class Codes: F16D 2121/24 using motors
• CPC Class Codes: F16D 2125/40 Screw-and-nut
• CPC Class Codes: F16D 2125/42 Rack-and-worm gears
• CPC Class Codes: F16D 2125/48 with parallel stationary axes, e.g. spur gears
• CPC Class Codes: F16D 65/186 with full-face force-applying member, e.g. annular
• CPC Class Codes: F16D 65/567 for mounting on a disc brake

Abstract

A system and method for establishing a running clearance position for an electromechanical actuator (28), wherein the running clearance is based on an actuator ram (34) position attained during a force application to a brake stack (30). In particular, a running clearance calibrator (66) determines a position value corresponding to a position of the force applicator when retraction from an application of force on the brake stack commences. The running clearance calibrator also generates a running clearance position as a function of the position value.

Claims

1. A controller for an electromechanical actuator operative to apply a braking force to brake a wheel of a vehicle, the electromechanical brake actuator having a motor driven to control the displacement of a force applicator relative to a brake stack, the controller comprising a running clearance calibrator that determines a position value corresponding to a position of the force applicator during a braking cycle when retraction from an application of force on the brake stack commences and that generates a running clearance position as a function of the position value.

2. The controller of claim 1, wherein the running clearance position is generated by combining the position value, a reference running clearance value and a brake deflection value that corresponds to force applied by the force applicator to achieve compression of the brake stack.

3. The controller of claim 2, wherein the combining subtracts the brake deflection value and the reference running clearance from the position value.

4. The controller of claim 1, wherein the running clearance calibrator includes a brake deflection look-up table for outputting a brake deflection value based on a force value corresponding to force applied by the force applicator to compress the brake stack.

5. The controller of claim 1, wherein the running clearance calibrator includes a force sampler and a retraction detector, the force sampler holding a sampled force value as the force applied by the force applicator to achieve the compression of the brake stack when the retraction detector detects the commencement of the retraction.

6. The controller of claim 1, further comprising a motor driver to drive the motor to position the force applicator at a location corresponding to about the running clearance position when braking is not commanded.

7. The controller of claim 1, wherein the running clearance calibrator includes a position sampler and a retraction detector, the position sampler holding a sampled position value as the position value when the retraction detector detects the commencement of the retraction.

8. The controller of claim 1, wherein the vehicle comprises an aircraft.

9. An electromechanical braking system, comprising:

an electromechanical actuator operative to apply a braking force to brake a wheel of a vehicle and having a motor driven to control displacement of a force applicator relative to a brake stack;

a controller including a running clearance calibrator that determines a position value corresponding to a position of the force applicator during a braking cycle when retraction from an application of force on the brake stack commences and that generates a running clearance position as a function of the position value;

a position sensor that provides force applicator position feedback data to the controller; and

a force sensor that provides force applicator force feedback data to the controller.

10. The system of claim 9, wherein the running clearance position is generated by combining the position value, a reference running clearance value and a brake deflection value that corresponds to force applied by the force applicator to achieve compression of the brake stack.

11. The system of claim 10, wherein the combining subtracts the brake deflection value and the reference running clearance from the position value.

12. The system of claim 9, wherein the running clearance calibrator includes a brake deflection look-up table for outputting a brake deflection value based on a force value corresponding to force applied by the force applicator to compress the brake stack.

13. The system of claim 9, wherein the running clearance calibrator includes a force sampler and a retraction detector, the force sampler holding a sampled force value as the force applied by the force applicator to achieve the compression of the brake stack when the retraction detector detects the commencement of the retraction.

14. The system of claim 9, further comprising a motor driver to drive the motor to position the force applicator at a location corresponding to about the running clearance position when braking is not commanded.

15. The system of claim 9, wherein the running clearance calibrator includes a position sampler and a retraction detector, the position sampler holding a sampled position value as the position value when the retraction detector detects the commencement of the retraction.

16. The system of claim 9, wherein the vehicle comprises an aircraft.

17. A method of adjusting a running clearance of an electromechanical actuator that is operative to apply a braking force to brake of a wheel of a vehicle, the electromechanical brake actuator having a motor driven to control the displacement of a force applicator relative to a brake stack, comprising:

determining a position value corresponding to a position of the force applicator during a braking cycle when retraction from an application of force on the brake stack commences; and

generating a running clearance position as a function of the position value.

18. The method of claim 17, wherein the generating combines the position value, a reference running clearance value and a brake deflection value that corresponds to force applied by the force applicator to achieve compression of the brake stack.

19. The method of claim 18, wherein the combining includes subtracting the brake deflection value and the reference running clearance from the position value.

20. The method of claim 17, further comprising commanding the motor to position the force applicator at a location corresponding to the running clearance position when braking is not commanded.

21. The method of claim 17, wherein the determining and the generating are carried out each time the force applicator is retracted from application of force on of the brake stack to generate a calibrated running clearance position that accounts for thermal expansion and contraction of the electromechanical brake actuator and wear of the brake stack.

22. The method of claim 17, wherein the determining the position value includes sampling the force applicator position upon the detection of the retraction.

23. The method of claim 17, further comprising sampling force applied by the force applicator on the brake stack upon the detection of the retraction.

24. The method of claim 23, further comprising translating the sampled force to the brake deflection value.

25. The method of claim 24, wherein the translating is carried out using a look-up table.

26. The method of claim 17, wherein the vehicle comprises an aircraft.