Tachometer for tires

• US 7,997,128 B2
• Filed: 04/25/2005
• Issued: 08/16/2011
• Est. Priority Date: 04/26/2004
• Status: Expired due to Fees

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation), Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Perrier, Bernard, Robert, Michel, Jeandey, Christian
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US11/587,563
• Publication Number:
  US 20080251172A1
• Time in Patent Office: 2,304 Days
• Field of Search: None
• US Class Current: 73/146
• CPC Class Codes: G01C 22/02 by conversion into electric waveforms and subsequent integration, e.g. using tachometer generator G01C22/002, G01C22/004, G01C22/006 take precedence

Abstract

A device for counting the rotations of a tire on a vehicle using the deformations that the tire undergoes on each rotation of the wheel, comprising a casing, a sensor intended to generate an electrical signal on each rotation of the wheel, and connection means intended to mechanically connect the casing and the sensor to the surface of the tire. The sensor is in the form of a passive sensor in one piece with the casing, whereof the signals emitted are in proportion with the variations over time in a magnetic flux through the said passive sensor, and a magnetic field generator is arranged opposite the passive sensor. The connection means mechanically connect the casing to a first surface A and the magnetic field generator to a second surface B, the two surfaces A and B being substantially coplanar and offset from one another in a direction D by a given distance L. The electrical signal is produced by the relative displacements of the said passive sensor and the said magnetic field generator.

Claims

1. A device for counting rotations of an object undergoing deformation during a rotation, comprising:

two parts subject to relative movement under effect of the deformation, the first part including a magnetic field generator and the second part including a sensor sensitive to a magnetic field generated by the magnetic field generator;

connection means mechanically connecting the second part to a first surface of the object and connecting the first part to a second surface of the object, the first and second surfaces of the object being offset from one another;

an interpreter configured to emit a pulse each time said device detects at least one cycle of signals emitted by the sensor sensitive to the magnetic field generated by the magnetic field generator; and

counting means connected to the interpreter.

2. The device according to claim 1, wherein the sensor is a passive sensor.

3. The device according to claim 1, wherein the magnetic field generator is a magnet.

4. The device according to claim 1, wherein one of the two parts is connected to the object by a resilient member.

5. The device according to claim 4, wherein the resilient member contributes to defining a reference position of the sensor in relation to the magnetic field generator.

6. The device according to claim 1, wherein the interpreter comprises a comparator.

7. The device according to claim 1, wherein the interpreter comprises means for amplifying signals.

8. The device according to claim 1, wherein the counting means comprises a counter which, each time said counter receives a predetermined number of pulses from the interpreter, transmits a pulse to a microprocessor including means for storing a number of pulses received from the counter.

9. The device according to claim 8, further comprising

means for transmitting to an outside data indicating the number of pulses stored by the microprocessor.

10. The device according to claim 1, further comprising:

an autonomous system of electrical power supply to the electrical components.

11. A tire equipped with the device according to claim 1.

12. The tire according to claim 11, wherein the first surface is arranged on an inner surface bead of the tire.

13. The tire according to claim 12, wherein the second surface is arranged substantially radially outwards in relation to the first surface.

14. The tire according to claim 12, wherein the first surface is arranged at a spacing greater than 50 mm from a radially inward end of the inner surface of the tire.

15. The tire according to claim 11, wherein the device is arranged on an inner surface of a crown of the tire, and wherein the first and second surfaces are oriented substantially in a circumferential direction.

16. The tire according to claim 11 wherein the tire is mountable on a rim having rim hooks of a given height and the device is arranged on an outer surface of one sidewall of the tire, at a radial distance greater than the given height of the rim hooks.

17. A device for counting rotations of a tire on a vehicle using deformations that the tire undergoes on each rotation of a wheel, comprising

a casing;

a sensor configured to generate an electrical signal on each rotation of the wheel; and

connection means for mechanically connecting the casing and the sensor to a surface of the tire;

wherein the sensor comprises

a magnetic field generator, and

a sensor sensitive to a magnetic field and in one piece with the casing, arranged opposite the magnetic field generators;

wherein said connection means mechanically connect the casing to a first surface and the magnetic field generator to a second surface B, the first and second surfaces being substantially coplanar and offset from one another in a direction by a given distance L; and

wherein said electrical signal is produced by relative displacements of said magnetic field generator and the sensor sensitive to the magnetic field.

18. The device according to claim 17, wherein the sensor sensitive to the magnetic field is a passive sensor.

19. The device according to claim 18, wherein the passive sensor is a loop of conductive wire.

20. The device according to claim 17, wherein the connection means are arranged such that a relative displacement normal to the direction of the first and second surfaces causes a relative displacement of the magnetic field generator and the sensor substantially normal to the direction.

21. The device according to claim 20, wherein the magnetic field generator and the sensor sensitive to the magnetic field are arranged in opposition in a direction normal to the direction.

22. The device according to claim 21, wherein the connection means, the casing and the sensor sensitive to the magnetic field are arranged in an L shape.

23. The device according to claim 22, wherein the connection means and the sensor comprise a flexible soleplate having a first face configured for permanent connection to a surface of the tire and at least one connection element to which the casing is fixed at a given spacing in relation to the flexible soleplate.

24. The device according to claim 23, wherein the magnetic field generator is embedded in the soleplate.

25. The device according to claim 23, wherein the casing, the element for connecting the casing, and the soleplate are generally U-shaped.

26. The device according to claim 21, wherein the connection means for connecting the magnetic field generator comprises a resilient connection element of arcuate elongate shape extending in the direction between the second surface and a zone of the casing or element for connecting the casing which is opposite the first surface, the magnetic field generator and the sensor sensitive to the magnetic field being arranged in opposition between two ends of the element for connecting the sensor.

27. The device according to claim 26, wherein the connection means comprise a flexible soleplate connecting the first and second surfaces.

28. The device according to claim 21, wherein the connection means for connecting the magnetic field generator comprises a resilient connection element of arcuate elongate shape extending in the direction between the second surface and another surface arranged beyond the first surface, the magnetic field generator and the sensor sensitive to the magnetic field being arranged in opposition between two ends of the resilient connection element for connecting the magnetic field generator.

29. The device according to claim 28, wherein the connection means comprise a flexible soleplate connecting the first, second and other surfaces.

30. The device according to claim 20, wherein the magnetic field generator and the sensor sensitive to the magnetic field are arranged in opposition in a direction parallel to the direction.

31. The device according to claim 30, wherein the connection means comprise an element for connecting the casing separating the casing from the first surface by a given height and an element connecting the magnetic field generator separating the magnetic field generator from the second surface by a given height, and wherein the sensor sensitive to the magnetic field is in one piece with the casing and is arranged at a height in relation to the first surface which is substantially identical to a height separating the magnetic field generator from the second surface.

32. The device according to claim 17, wherein the connection means are arranged such that a relative displacement normal to the direction of the first and second surfaces causes a relative displacement of the sensor sensitive to the magnetic field and the magnetic field generator substantially parallel to the direction.

33. The device according to claim 32, wherein the connection means for connecting the magnetic field generator comprise two elongate arms with a connection point in an L shape, such that the magnetic field generator is arranged substantially at the connection point, a first arm of the two elongate arms extends from the connection point to an adjoining zone substantially on the first surface and a second arm of the two elongate arms extends from the connection point to the second surface.

34. The device according to claim 33, wherein the connection means comprise a flexible soleplate connecting the first and second surfaces.

35. The device according to claim 17, wherein a distance L between the first surface and the second surface is greater than 20 mm.

36. The device according to claim 17, wherein a distance separating the magnetic field generator and the sensor sensitive to the magnetic field is between 10 and 15 mm in a free state.

37. The device according to claim 17, wherein the magnetic field generator is a rubber mix including magnetic particles.

38. The device according to claim 17, wherein the magnetic field generator is a permanent samarium-cobalt magnet.

39. The device according to claim 17, further comprising:

an interpreter which emits a pulse each time the interpreter detects at least one cycle of signals emitted by the sensor sensitive to the magnetic field.

40. The device according to claim 39, wherein the interpreter includes a comparator.

41. The device according to one of claim 39, wherein the interpreter includes means for filtering the signals emitted by the sensor sensitive to the magnetic field.

42. The device according to claim 39, wherein the interpreter includes means for amplifying signals.

43. The device according to claim 39, further comprising:

a counting means connected to the interpreter.

44. The device according to claim 43, wherein the counting means comprises a counter which, each time the counter receives a predetermined number of pulses from the interpreter, transmits a pulse to a microprocessor including means for storing a number of pulses received from the counter.

45. The device according to claim 44, further comprising:

a device for transmitting data indicating the number of pulses stored by the microprocessor.

46. The device according to claim 39, further comprising:

an autonomous electrical power supply system configured to supply power to the electronic components.

47. The device according to claim 17, wherein the casing is a printed circuit carrying, in addition to the passive sensor, means for supplying electrical power and signal processing.

48. A tire equipped with the device according to claim 17.