Method and apparatus for detecting timing belt damage using link-coupled feedback

• US 6,523,400 B1
• Filed: 08/24/2001
• Issued: 02/25/2003
• Est. Priority Date: 03/17/2000
• Status: Expired due to Fees

• Current Assignee: Adel Abdel Aziz Ahmed
• Original Assignee: Adel Abdel Aziz Ahmed
• Inventors: Ahmed, Adel Abdel Aziz
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US09/939,090
• Time in Patent Office: 550 Days
• Field of Search: 731/16, 731/172, 731/173, 731/181, 731/19.R, 340/425.5, 340/438, 340/439
• US Class Current: 73/114.77
• CPC Class Codes: G01M 13/023 Power-transmitting endless elements, e.g. belts or chains

Abstract

Apparatus for monitoring a change of condition in a drive belt, such as timing belt, includes a first inductance coil, a second inductance coil, and an electrically conductive loop embedded in the drive belt. Such a conductive wire or strip embedded in the belt material in the form of a closed loop tends to exhibit damage typically some time before belt failure is imminent. The conductive loop forms a mutual inductive link coupling between the first and second inductance coils. An amplifier has an input coupled to the first coil and an output coupled to the second coil poled for causing oscillation and a detector detects change in the oscillation.

Claims

1. Apparatus for monitoring a change of condition in a drive belt, said apparatus comprising

a first inductance coil;

a second inductance coil;

an electrically conductive loop coupled for movement with said drive belt, said conductive loop forming a mutual inductive link coupling between said first and second inductance coils, wherein said electrically conductive loop undergoes a change in impedance indicative of impairment of integrity in said belt;

an amplifier having an input coupled to said first coil and an output coupled to said second coil for forming a feedback loop for sustaining electrical oscillations; and

a detector coupled said feedback loop for sensing a change in said electrical oscillations caused by said change in impedance.

2. Apparatus for monitoring a change of condition in a drive belt as recited in claim 1, wherein said electrically conductive loop comprises a conductor embedded at least in part in said belt.

3. Apparatus for monitoring a change of condition in a drive belt as recited in claim 2, wherein said change in impedance is indicative of impairment of integrity in said belt.

4. Apparatus for monitoring a change of condition in a drive belt as recited in claim 2, wherein said belt is a toothed timing belt and wherein said electrically conductive loop follows a path in said belt in proximity to its teeth for providing an impedance change indication of tooth damage.

5. Apparatus for monitoring a change of condition in a drive belt as recited in claim 4, wherein said electrically conductive loop comprises a plurality of turns.

6. Apparatus for monitoring a change of condition in a drive belt, said apparatus comprising

a first inductance coil;

a second inductance coil;

an electrically conductive loop coupled for movement with said drive belt, said conductive loop forming a mutual inductive link coupling between said first and second inductance coils and exhibiting an impedance change indicative of a change of condition in said drive belt;

an amplifier having an input coupled to said first coil and an output coupled to said second coil for forming an electrical oscillatory loop; and

a detector coupled to said output of said amplifier for sensing a change in said oscillatory loop caused by said impedance change.

7. Apparatus for monitoring a change of condition in a drive belt as recited in claim 6, wherein said electrically conductive loop comprises a conductor embedded at least in part in said belt.

8. Apparatus for monitoring a change of condition in a drive belt as recited in claim 7, wherein said impedance change is indicative of impairment of integrity in said belt.

9. Apparatus for monitoring a change of condition in a drive belt as recited in claim 7, wherein said belt is a toothed timing belt and wherein said electrically conductive loop follows a path in said belt in proximity to its teeth for providing an impedance change indication of tooth damage.

10. Apparatus for monitoring a change of condition in a drive belt as recited in claim 6, wherein said electrically conductive loop comprises a plurality of turns.

11. Apparatus for monitoring a change of condition in a drive belt, said apparatus comprising

a first inductance coil;

a second inductance coil;

an electrically conductive loop coupled for movement with said drive belt, said conductive loop forming a mutual inductive link coupling between said first and second inductance coils, conductive loop exhibiting an impedance change indicative of said change of condition in said drive belt ; and

an amplifier having an input coupled to said first coil and an output coupled to said second coil, said amplifier input and output being poled so as to provide a positive feedback loop comprising said first and second coils and said link coupling for causing electrical oscillation in said feedback loop; and

a detector for detecting a change in said oscillation caused by said impedance change.

12. Apparatus for monitoring a change of condition in a drive belt as recited in claim 11, wherein said detector detects a change in amplitude of said oscillation.

13. Apparatus for monitoring a change of condition in a drive belt as recited in claim 11, wherein said detector detects a change in frequency of said oscillation.

14. Apparatus for monitoring a change of condition in a drive belt by detecting an impedance change indicative of said change of condition in a wire loop at least partially embedded in said drive belt, said apparatus comprising:

an amplifier;

a first inductance coupled to an input of said amplifier;

a second inductance coupled to an output of said amplifier, said first and second inductances being coupled by mutual inductance to said wire loop such that said wire loop provides a link coupling between said first and second inductances so as to form a positive feedback loop with said amplifier for causing electrical oscillation in said feedback loop; and

a detector coupled to said second inductance for monitoring a change in said oscillation caused by said impedance change.

15. Apparatus for monitoring a change of condition in a drive belt as recited in claim 14, wherein said electrically conductive loop comprises a conductor embedded at least in part in said belt.

16. Apparatus for monitoring a change of condition in a drive belt as recited in claim 14, wherein said electrically conductive loop undergoes a change in its impedance indicative of impairment of integrity in said belt.

17. Apparatus for monitoring a change of condition in a drive belt as recited in claim 15, wherein said belt is a toothed timing belt and wherein said electrically conductive loop follows a path in said belt in proximity to its teeth for providing an impedance change indication of tooth damage.

18. Apparatus for monitoring a change of condition in a drive belt as recited in claim 17, wherein said electrically conductive loop comprises a plurality of turns.

19. Apparatus for monitoring a change of condition in a drive belt, comprising:

means for providing a closed loop conductive path along the length of said drive belt and for exhibiting an impedance change in said closed loop indicative of said change of condition in said drive belt;

means for providing a first self-inductance;

means for providing mutual inductance coupling between said means for providing a first self-inductance and said means for providing a closed loop conductive path;

means for providing a second self-inductance;

means for providing mutual inductance coupling between said means for providing a second self-inductance and said means for providing a closed loop conductive path;

means for providing amplification between said means for providing a first self-inductance and said means for providing a second self-inductance for establishing a closed positive feedback loop for causing electrical oscillation in said feedback loop; and

means for detecting a change in said oscillation caused by said impedance change.

20. A method for monitoring a change of condition in a drive belt, said method comprising the steps of:

associating an electrically conductive loop for movement with said drive belt for causing said conductive loop to exhibit an impedance change indicative of said change of condition in said drive belt;

mutually inductively coupling a first inductance coil and said conductive loop;

mutually inductively coupling a second inductance coil and said conductive loop, such that said conductive loop forms a link coupling between said first and second inductance coils;

coupling an amplifier between said first and second coils for forming a positive feedback loop comprising said first and second coils, and said link coupling, for causing electrical oscillation in said feedback loop; and

detecting a change in said oscillation caused by said impedance change.

21. A method for monitoring a change of condition in a drive belt as recited in claim 20, wherein said step of associating an electrically conductive loop for movement with said drive belt comprises a step of at least partially embedding said conductive loop in said belt.