Tachometer For Tires

• US 20080251172A1
• Filed: 04/25/2005
• Published: 10/16/2008
• Est. Priority Date: 04/26/2004
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Perrier, Bernard, Robert, Michel, Jeandey, Christian
• Granted Patent: US 7,997,128 B2
• Time in Patent Office: Days
• US Class Current: 152/152.1
• 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

6-1. The device according to claim 1, comprising an interpreter which emits a pulse each time it detects at least one cycle of signals emitted by the sensor.

12. 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,

wherein the sensor is in the form of

a magnetic field generator, and

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

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

13. The device according to claim 12, in which the said sensor sensitive to the magnetic field is a passive sensor.

14. The device according to claim 13, in which the said passive sensor is a loop of conductive wire.

15. The device according to claim 12, in which the connection means are such that a relative displacement normal to the direction D of the surfaces A and B brings about a relative displacement of the magnetic field generator and the passive sensor substantially normal to the direction D.

16. The device according to claim 15, in which the magnetic field generator and the sensor sensitive to the magnetic field are arranged in opposition in a direction normal to the direction D.

17. The device according to claim 16, in which the connection means, the casing and the sensor sensitive to the magnetic field are arranged in an L shape.

18. The device according to claim 17, in which the means for connecting the casing and the sensor comprise a flexible soleplate having a first face intended to be permanently connected to the surface of the tire and at least one connection element to which the casing is fixed at a given spacing in relation to the soleplate.

19. The device according to claim 18, in which the magnetic field generator is embedded in the soleplate.

20. The device according to claim 18, in which the casing, the element for connecting the casing and the soleplate are generally U-shaped.

21. The device according to claim 16, in which the means for connecting the magnetic field generator are in the form of a resilient connection element of arcuate elongate shape extending in the direction D between the surface B and a zone of the casing or element for connecting the casing which is opposite the surface A, the magnetic field generator and the sensor sensitive to the magnetic field being arranged in opposition between the two ends of the said element for connecting the sensor.

22. The device according to claim 21, in which the connection means comprise a flexible soleplate connecting the surfaces A and B.

23. The device according to claim 16, in which the means for connecting the magnetic field generator are in the form of a resilient connection element of arcuate elongate shape extending in the direction D between the surface B and a surface B′

arranged beyond the surface A, the magnetic field generator and the sensor sensitive to the magnetic field being arranged in opposition between the two ends of the said element for connecting the magnetic field generator.

24. The device according to claim 23, in which the connection means comprise a flexible soleplate connecting the surfaces A, B and B′

.

25. The device according to claim 15, in which the magnetic field generator and the sensor sensitive to the magnetic field are arranged in opposition in a direction parallel to the direction D.

26. The device according to claim 25, in which the connection means comprise an element for connecting the casing separating the said casing from the surface A by a given height and an element connecting the magnetic field generator separating the said magnetic field generator from the surface B by a given height, and in which the sensor sensitive to the magnetic field is in one piece with the casing and is arranged at a height in relation to the surface A which is substantially identical to the height separating the magnetic field generator from the surface B.

27. The device according to one of claim 12, in which the connection means are such that a relative displacement normal to the direction D of the surfaces A and B brings about a relative displacement of the sensor sensitive to the magnetic field and the magnetic field generator substantially parallel to the direction D.

28. The device according to claim 27, in which the means for connecting the magnetic field generator comprise two elongate arms with a connection point in an L shape, such that the generator is arranged substantially at the said connection point, the first arm extends from the connection point to an adjoining zone substantially on the surface A and the second arm extends from the connection point to the surface B.

29. The device according to claim 28, in which the connection means comprise a flexible soleplate connecting the surfaces A and B.

30. The device according to claim 12, in which the distance L between the surface A and the surface B is greater than 20 mm.

31. The device according to claim 12, in which the distance H separating the magnetic field generator and the sensor sensitive to the magnetic field is between 10 and 15 mm in the free state.

32. The device according to claim 12, in which the said magnetic field generator is a rubber mix including magnetic particles.

33. The device according to claim 12, in which the said magnetic field generator is a permanent magnet of the samarium-cobalt type.

34. The device according to claim 12, including an interpreter which emits a pulse each time it detects at least one cycle of signals emitted by the sensor sensitive to the magnetic field.

35. The device according to claim 34, in which the interpreter includes a comparator.

36. The device according to claim 34, in which the interpreter includes means for filtering the signals emitted by the sensor sensitive to the magnetic field.

37. The device according to claim 34, in which the interpreter includes means for amplifying signals.

38. The device according to claim 34, including a counting means connected to the interpreter.

39. The device according to claim 38, in which the counting means is in the form of a counter which, each time it receives a predetermined number of pulses from the interpreter, transmits a pulse to a microprocessor including means for storing the number of pulses received from the counter.

40. The device according to claim 39, including a device for transmitting to the outside data indicating the number of pulses stored by the microprocessor.

41. The device according to claim 34, including an autonomous system of electrical power supply to the electronic components, such as a battery.

42. The device according to claim 12, in which the said casing is a printed circuit carrying, in addition to the said passive sensor, all the means for electrical power supply and signal processing.

49. A tire equipped with a device according to claim 12.