Vehicular sensors

• US 6,595,045 B1
• Filed: 10/16/2000
• Issued: 07/22/2003
• Est. Priority Date: 10/16/2000
• Status: Expired due to Fees

• Current Assignee: Calpine Corporation
• Original Assignee: Veridian Engineering Incorporated
• Inventors: Schabel, David G., Keppler, Todd H., Nowak, Chris J., Fuglewicz, Daniel P.
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US09/688,220
• Time in Patent Office: 1,009 Days
• Field of Search: 731/21, 731/29, 731/32, 701/70, 340/438, 340/453
• US Class Current: 73/129
• CPC Class Codes: B60T 17/08 Brake cylinders other than ultimate actuators with built-in wear-compensating mechanisms, ultimate actuators F16D
• CPC Class Codes: B60T 17/221 Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: F16D 2066/003 Position, angle or speed
• CPC Class Codes: F16D 66/00 Arrangements for monitoring working conditions, e.g. wear, temperature

Abstract

A brake stroke sensor and an steering sensor are individually and collectively provided. A brake stroke sensor includes a force-receiving plate, a second plate movable relative to the force-receiving plate, a spring disposed between the plates and operatively connected to the pushrod, a strain gauge bridge mounted on the force-receiving plate and a microcontroller capable of converting the strain gauge bridge signal into digital data. A steering sensor includes a mechanical interface operatively connected to a nonmoving member and a moving member, an encoder capable of transforming the rotational motion of the mechanical interface into an electrical signal, and a microcontroller capable of calculating, from the electrical signal, a count indicative of the relative positions of the members. A combined brake stroke and steering sensor may include individual and common elements of both the brake stroke and steering sensors described above. The brake stroke, steering sensor and combined brake stroke and steering sensor may utilize a modem for transmitting data to a system controller over an electrical bus.

Claims

1. A brake stroke sensor for determining a position of a brake actuator pushrod comprising:

a spring operatively connected to the pushrod to be compressed by pushrod movement;

a strain gauge, said strain gauge measuring a strain imparted by the spring and outputting a strain signal based on the strain; and

a microcontroller configured to convert said strain signal into an output signal indicative of said position of said brake actuator pushrod, said microcontroller storing coefficients of a nonlinear equation, said nonlinear equation representing a relationship between said strain signal and said position of said brake actuator pushrod.

2. A brake stroke sensor as in claim 1, wherein said microcontroller is configured to produce an output signal representative of the strain, and configured to store a unique address identifying said microcontroller.

3. A brake stroke sensor as in claim 1, further comprising a modem configured to modulate said output signal onto an electrical bus.

4. A brake stroke sensor as in claim 1, wherein said brake stroke sensor is configured to transmit data after said brake stroke sensor receives a request for data addressed to said brake stroke sensor'"'"'s own unique address.

5. A brake stroke sensor as in claim 1, wherein said microcontroller is configured to store and transmit calibration coefficients used to convert said output signal into a value indicative of the length of pushrod stroke.

6. A brake stroke sensor as in claim 1, wherein said strain signal is an analog voltage substantially proportional to a distance that said pushrod extends from a brake actuator.

7. A brake stroke sensor as in claim 1, wherein said spring comprises a return spring for returning a pushrod to a home position.

30. The brake stroke sensor of claim 1, wherein said output signal is indicative of an actual position of the pushrod throughout a continuous range.

8. A brake stroke sensor for determining a position of a brake actuator pushrod, comprising:

a force-receiving plate having a first surface and a second surface and a bore through said first and second surfaces, said pushrod passing through said bore;

a spring operatively connected to said pushrod and said force-receiving plate configured to be deflected during pushrod movement in a first direction;

a strain gauge bridge disposed on said force-receiving plate, said strain gauge bridge outputting a strain signal; and

a microcontroller configured to convert said strain signal into an output signal indicative of said position of said brake actuator pushrod, said microcontroller storing coefficients of a nonlinear equation, said nonlinear equation representing a relationship between said strain signal and said position of said brake actuator pushrod.

9. A force-receiving plate as in claim 8, wherein said first surface has a feature to align said spring and maintain said spring in concentric alignment with said pushrod.

10. A brake stroke sensor as in claim 8, wherein said second surface has a protrusion configured to support said force-receiving plate away from interior surfaces of a brake actuator.

11. A brake stroke sensor as in claim 10, wherein said protrusion has a groove configured to accept a retaining device.

12. A brake stroke sensor as in claim 10, further comprising:

said protrusion extends away from said second surface of said force-receiving plate and has at least a first section and a second section;

said first section has a first diameter and lies closer to said second surface than said second section, and said second section has a second diameter;

said diameter of said first section is larger than said diameter of said second section; and

said second section penetrates a brake actuator through a bore in said brake actuator.

13. A brake stroke sensor as in claim 8, wherein said strain gauge bridge comprises at least two strain gauges configured to measure strain imposed upon said force-receiving plate across substantially the entire surface of said force-receiving plate.

14. A brake stroke sensor as in claim 8, wherein said strain gauge bridge comprises at least two strain gauges configured to cover substantially a stress concentration annulus located approximately about an intersection of said second surface and said protrusion.

15. A brake stroke sensor as in claim 10, wherein a surface of said force-receiving plate includes a member configured to improve the stiffness of said force-receiving plate.

16. A brake stroke sensor as in claim 15, wherein said member is an annular ring.

17. A brake stroke sensor as in claim 8, wherein said strain gauge bridge comprises:

at least four strain gauges, mounted approximately ninety degrees apart from each other, each lying on a plane of said second surface; and

a strain gauge measurement axis for each strain gauge being roughly parallel to an imaginary line extending from the center of said force-receiving plate to an outer edge of said force-receiving plate.

18. A strain gauge bridge as in claim 17, wherein said strain gauge bridge is configured in a Wheatstone type configuration.

19. A strain gauge bridge as in claim 17, wherein said strain gauge bridge includes at least two resistors.

20. A strain gauge bridge as in claim 17, wherein a connector is integrated for carrying a strain gauge bridge excitation voltage and said strain signal.

21. A brake stroke sensor as in claim 8, wherein said strain gauge bridge comprises:

at least two strain gauges, mounted approximately one hundred and eighty degrees apart from each other, each lying on a plane of said second surface; and

a strain gauge measurement axis for each strain gauge being roughly parallel to an imaginary line extending from the center of said force-receiving plate to an outer edge of said force-receiving plate.

22. A strain gauge bridge as in claim 21, wherein said strain gauge bridge is configured in a Wheatstone type configuration.

23. A strain gauge bridge as in claim 21, wherein said bridge includes at least two resistors.

24. A strain gauge bridge as in claim 21, wherein a connector is integrated to carry a strain gauge bridge excitation voltage and said strain signal.

31. The brake stroke sensor of claim 8, wherein said output signal is indicative of an actual position of the pushrod throughout a continuous range.

25. A method of determining a position of a brake actuator pushrod in a brake actuator'"'"'s range of motion comprising:

compressing a spring by movement of the pushrod thereby imparting a strain to a strain gauge bridge operatively connected to the spring;

measuring the strain imparted to the strain gauge bridge, whereby the measured strain is proportional to strain gauge bridge output;

digitizing an analog representation of the measured strain to produce a digitized measured strain indicative of said position of said brake actuator pushrod;

storing the digitized measured strain in a microcontroller, whereby the microcontroller has a unique address;

storing coefficients of a nonlinear equation in said microcontroller, said nonlinear equation representing a relationship between said strain signal and said position of said brake actuator pushrod; and

transmitting the digitized measured strain from the microcontroller to a system controller upon being addressed by the system controller.

26. The method of claim 25, wherein said microcontroller compares said digitized measured strain to a maximum value stored in said microcontroller and replaces said maximum value with said digitized measured strain if said digitized measured strain is greater than said maximum value.

27. The method of claim 25, wherein the system controller and the microcontroller interface through a modem.

28. The method of claim 27, wherein a single electrical power line and a chassis ground connect the modem with the system controller.

29. The method of claim 25, wherein said strain gauge bridge output is substantially proportional to the length of the pushrod as the pushrod extends from a brake actuator.

32. The method of claim 25, wherein said output signal is indicative of an actual position of the pushrod throughout a continuous range.