System, tyre and method for determining the behaviour of a tyre in motion

• US 20040064219A1
• Filed: 05/01/2003
• Published: 04/01/2004
• Est. Priority Date: 03/16/2000
• Status: Active Grant

• Current Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Original Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Inventors: Mancosu, Federico, Matrascia, Giuseppe, Speziari, Diego Ettore, Monguzzi, Carlo
• Granted Patent: US 6,959,593 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: B60C 23/0493 for attachment on the tyre
• CPC Class Codes: B60C 23/06 Signalling devices actuated by deformation of the tyre , e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle
• CPC Class Codes: B60C 23/064 comprising tyre mounted deformation sensors, e.g. to determine road contact area
• CPC Class Codes: B60G 2204/113 Tyre related sensors
• CPC Class Codes: B60R 16/0237 circuits concerning the atmospheric environment meteorology G01W
• CPC Class Codes: B60T 2210/13 Aquaplaning, hydroplaning
• CPC Class Codes: B60T 2220/02 Driver type; Driving style; Driver adaptive features
• CPC Class Codes: B60T 2240/04 Tire deformation
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00

Abstract

A system for determining interaction between a tyre and a contact surface during movement of a motor vehicle includes at least one first sensor and processing means. The at least one first sensor includes one or more first elongated piezoelectric elements which extend along at least a first portion of the tyre. The at least one first sensor supplies a first signal to the processing means. The first signal is generated by rotation of the tyre and is generated cyclically with each revolution of the tyre. The processing means detects variations in time intervals between distinctive elements of the first signal. A tyre including the system, a kit for detecting behaviour of a tyre moving with respect to a contact surface, a method for monitoring events correlated with interactions between tyres of a moving vehicle and a contact surface, and related systems, tyres, methods, and vehicles are also disclosed.

Claims

1. System for the continuous determination of the interaction between a tyre (1) and the ground during the movement of a motor vehicle, the said tyre (1) comprising a casing (2), a tread (3), belt plies (6), sidewalls (4), beads (5) and at least a first sensor (7;

307;

407;

507;

607;

707;

807;

902) associated for operation with processing means (8), characterized in that the said first sensor (7;

307;

407;

507;

607;

707;

807;

902) comprises an elongate piezoelectric element (10;

12;

20;

210) which extends along at least a first portion of the said tyre (1) and is capable of supplying a first signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said first signal having distinctive elements and the said processing means (8) being capable of acquiring the said first signal and detecting variations of the time interval between predetermined distinctive elements of the said first signal.

2. System according to claim 1, characterized in that the said first signal is proportional to the variations of deformation undergone by the said first piezoelectric sensor (7;

307;

407;

507;

607;

707;

807;

902) during the rotation of the said tyre (1).

3. System according to claim 1, characterized in that the said first piezoelectric sensor (7) is applied along at least a portion of a predetermined circumference of the said tyre (1).

4. System according to claim 3, characterized in that the said circumference is an equatorial circumference.

5. System according to claim 1, characterized in that the said first piezoelectric sensor (307) is applied along a portion of a meridian profile (16) of the said tyre (1).

6. System according to any of the preceding claims 1 to 5, characterized in that the said first piezoelectric sensor (7) is applied to an inner surface of the said casing (2).

7. System according to any of the preceding claims 1 to 5, characterized in that the said first piezoelectric sensor (7) is embedded in the said casing (2), in the said belt plies (6), in the said tread (3) or in a bead (5).

8. System according to claim 1, characterized in that it comprises at least a second piezoelectric sensor (107;

207) associated with the said tyre (1), the said second piezoelectric sensor (107;

207) comprising an elongate piezoelectric element (12) which extends along at least a second portion of the said tyre (1) and is capable of supplying a second signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said second signal having distinctive elements and the said processing means (8) being capable of acquiring the said second signal and detecting variations of the time interval between predetermined distinctive elements of the said first and second signal.

9. System according to claim 8, characterized in that the said second signal is proportional to the variations of deformation undergone by the said second piezoelectric sensor (107;

207) during the rotation of the said tyre (1).

10. System according to claim 8, characterized in that the said second piezoelectric sensor (107) is applied along a circumference forming part of the said bead (5).

11. System according to claim 8, characterized in that the said second piezoelectric sensor (207) is applied along a bead portion of a meridian profile (16) of the said tyre (1).

12. System according to any one of the preceding claims 1 to 11, characterized in that the said first and second piezoelectric sensors (10) are coaxial piezoelectric cables.

13. System according to claim 12, characterized in that the said coaxial piezoelectric cable (10) comprises a central core (11) made from electrically conducting material, an insulating layer (12) formed by a piezoelectric polymer, a mesh wrapping (13) made from an electrically conducting material, and a sheath (14).

14. System according to any one of the preceding claims 1 to 11, characterized in that the said piezoelectric sensor (407;

507) comprises a cable (110;

210) consisting of piezoelectric portions (20) and non-piezoelectric electrically conducting portions (21), connected electrically.

15. System according to claim 14, characterized in that the said piezoelectric portions (20) and the said non-piezoelectric conducting portions (21) follow each other in an alternating sequence.

16. System according to claim 15, characterized in that the said piezoelectric portions (20) and the said non-piezoelectric conducting portions (21) follow each other in a zigzag configuration.

17. System according to claim 15, characterized in that the said piezoelectric portions (20) and the said non-piezoelectric conducting portions (21) are aligned.

18. System according to claim 15, characterized in that the said piezoelectric cable (210) comprises a central conducting core (211), tubular portions (112) of insulating piezoelectric material and tubular portions (121) of non-piezoelectric insulating material which cover the said core and follow each other longitudinally in an alternating arrangement, an electrically conducting mesh (213) which is wrapped around the said portions (112, 121) and a covering sheath (214).

19. System according to claim 1, for the continuous determination of the interaction between a tyre (1) mounted on its mounting rim and the ground during the movement of a motor vehicle, characterized in that the said first piezoelectric sensor (707) is housed in an annular groove (35) recessed into a shoulder (34) of a rim (15) and remains in contact with the outer surface of the said bead (5).

20. System according to claim 19, characterized in that the said first piezoelectric sensor (807) is fitted to a shoulder (34) of a rim (15) and comprises sections (36) that are sensitive to the deformation of a bead (5) and are on the inside of the said shoulder (34), alternating with sections (37) that are insensitive to the deformation of the said bead (5) and are on the outside of the said shoulder (34).

21. System according to claims 20, characterized in that a radio signal transmitter (39) is fitted to the said shoulder (34) of the said rim (15).

22. Tyre (1) for a motor vehicle, comprising a casing (2), a tread (3), belt plies (6), sidewalls (4), beads (5) and at least a first sensor (7;

307;

407;

507;

607;

707;

807;

902), characterized in that the said first sensor (7;

307;

407;

507;

607;

707;

807;

902) comprises an elongate piezoelectric element (10;

12;

20;

210) which extends along at least a first portion of the said tyre (1) and is capable of supplying a first signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said first signal having distinctive elements and the variations of the time interval between predetermined distinctive elements of the said first signal being indicative of the variations of angular velocity of the said tyre (1).

23. Tyre (1) according to claim 22, characterized in that the said first signal is proportional to the variations of deformation undergone by the said first piezoelectric sensor (7;

307;

407;

507, 607;

707;

807;

902) during the rotation of the said tyre (1).

24. Tyre (1) according to claim 22, characterized in that the said first piezoelectric sensor (7) is applied along at least one portion of a predetermined circumference of the said tyre (1).

25. Tyre (1) according to claim 24, characterized in that the said circumference is an equatorial circumference.

26. Tyre (1) according to claim 22, characterized in that the said first piezoelectric sensor (307) is applied along a portion of a meridian profile (16) of the said tyre (1).

27. Tyre (1) according to any one of the preceding claims 22 to 26, characterized in that the said first piezoelectric sensor (7) is applied to an inner surface of the said casing (2).

28. Tyre (I) according to any one of the preceding claims 22 to 26, characterized in that the said first piezoelectric sensor (7) is embedded in the said casing (2), in the said belt plies (6), in the said tread (3) or in a bead (5).

29. Tyre (1) according to claim 22, characterized in that it comprises at least a second piezoelectric sensor (107;

207) comprising an elongate piezoelectric element (12) which extends along at least a second portion of the said tyre (1) and is capable of supplying a second signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said second signal having distinctive elements and the variations of the time interval between predetermined distinctive elements of the said second signal being indicative of the variations of angular velocity of the said tyre (1).

30. Tyre (1) according to claim 29, characterized in that the said second signal is also proportional to the variations of deformation undergone by the said second piezoelectric sensor (107;

207) during the rotation of the said tyre (1).

31. Tyre (1) according to claim 29, characterized in that the said second piezoelectric sensor (107) is applied along a circumference forming part of the said bead (5).

32. Tyre (1) according to claim 29, characterized in that the said second piezoelectric sensor (207) is applied along a bead portion of a meridian profile (16) of the said tyre (1).

33. Tyre (1) according to any one of the preceding claims 22 to 32, characterized in that the said first and second piezoelectric sensors (10) are coaxial piezoelectric cables.

34. Tyre (1) according to claim 33, characterized in that the said coaxial piezoelectric cable (10) comprises a central core (11) made from electrically conducting material, an insulating layer (12) formed by a piezoelectric polymer, a mesh wrapping.(13) made from electrically conducting material, and a sheath (14).

35. Tyre (1) according to any one of the preceding claims 22 to 32, characterized in that the said piezoelectric sensor (407;

507) comprises a cable (110;

210) consisting of piezoelectric portions (20) and non-piezoelectric electrically conducting portions (21), connected electrically.

36. Tyre (1) according to claim 35, characterized in that the said piezoelectric portions (20) and non-piezoelectric electrically conducting portions (21) follow each other in an alternating sequence.

37. Tyre (1) according to claim 36, characterized in that the said piezoelectric portions (20) and the said non-piezoelectric conducting portions (21) follow each other in a zigzag configuration.

38. Tyre (1) according to claim 36, characterized in that the said piezoelectric portions (20) and the said non-piezoelectric conducting portions (21) are aligned.

39. Tyre (1) according to claim 36, characterized in that the said piezoelectric cable (210) comprises a central conducting core (211), tubular portions (112) of insulating piezoelectric material and tubular portions (121) of non-piezoelectric insulating material which cover the said core and which follow each other longitudinally in an alternating arrangement, an electrically conducting mesh (213) which is wrapped around the said portions (112, 121) and a covering sheath (214).

40. Tyre (1) according to claim 22, characterized in that the said first piezoelectric sensor (607) is fitted to a base (30) of the said bead (5).

41. Tyre (1) according to claim 40, characterized in that the said first piezoelectric sensor (707) is fitted in a depression (33) in the said bead (5).

42. System for the continuous determination of the interaction between a tyre (1) and the ground during the movement of a motor vehicle, in which the said system includes a vehicle tyre (1) and processing means (8), the said tyre (1) being associated with at least a first sensor (7;

307;

407;

507, 607, 707, 807, 902);

characterized in that the said first sensor (7;

307;

407;

507, 607, 707, 807, 902) comprises an elongate piezoelectric element (10, 12;

20, 210) which extends along at least a first portion of the said tyre (1) and is capable of supplying a first signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said first signal having distinctive elements and the said processing means (8) being capable of acquiring the said first signal and detecting variations of the time interval between predetermined distinctive elements of the said first signal.

43. Tyre (1) for a motor vehicle associated with at least a first sensor (7;

307;

407;

507, 607, 707, 807, 902), characterized in that the said first sensor (7;

307;

407;

507, 607, 707, 807, 902) comprises an elongate piezoelectric element (10, 12;

20, 210) which extends along at least a first portion of the said tyre (1) and is capable of supplying a first signal which is generated by the rotation of the said tyre (1) and is formed cyclically on each revolution of the tyre (1), the said first signal having distinctive elements and the variations of the time interval between predetermined distinctive elements of the said first signal being indicative of the variations of angular velocity of the said tyre (1).

44. Vehicle wheel that includes tyre (1), rim (15) and device for detecting the behaviour of the tyre moving with respect to a contact surface, characterized in that the said device includes at least one sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), that emits a continuous and cyclical signal indicative of a state of mechanical stress of the wheel or of its variations with respect to a previous state, detected continuously and cyclically.

45. Vehicle including a body, at least one suspension, at least one wheel fitted with a tyre (1) and at least one device for controlling the behaviour of the moving vehicle, in which the said device is activated by a signal from the said wheel or wheels or part thereof, characterized in that the said signal is emitted continuously and cyclically by at least one sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), associated with the said wheel or wheels or part thereof, and in that the said signal is indicative of a state of mechanical stress of the wheel or of its variations with respect to a previous state and is detected continuously and cyclically.

46. Method for detecting an interaction between at least one moving tyre (1) and a contact surface by means of a signal emitted by a sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), associated with the said tyre (1) that includes the step of causing the generation of a continuous and cyclical signal indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically.

47. Method for detecting the behaviour of at least one moving tyre (1) with respect to a contact surface that includes the following steps:

causing the generation of a continuous and cyclical signal in relation to the continuously and cyclically detected movement of the said tyre (1);

comparing a plurality of cycles, or parts of cycles, of the said signal with each other.

48. Method for enabling a tyre (1) to generate a signal indicative of its own behaviour when moving with respect to a contact surface that includes the step of fitting the said tyre with a sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), for generating a continuous and cyclical signal indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically.

49. Method for enabling a tyre (1) to transmit a signal descriptive of its own behaviour when moving with respect to a contact surface that includes the following steps:

providing the said tyre (1) with a sensor (7;

307;

407;

507, 607, 707, 807, 902) for generating a continuous and cyclical signal indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically;

providing the said sensor (7;

307;

407;

507, 607, 707, 807, 902) with a transmitter (39, 903) capable of transmitting the said continuous and cyclical signal.

50. Method for enabling a tyre (1) mounted on a wheel rim (15) to generate a signal descriptive of its own behaviour when moving with respect to a contact surface that includes the step of providing the said tyre (1) with a sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), for generating a continuous and cyclical signal indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically.

51. Method for manufacturing a wheel inclusive of a tyre (1), rim (15) and sensor (7;

307;

407;

507, 607, 707, 807, 902), comprising an elongate piezoelectric element (10, 12;

20, 210), in such a way that it is capable of generating a signal descriptive of the behaviour of the tyre (1) when moving with respect to a contact surface, that includes the step of assembling the said tyre (1), the said rim (15) and the said sensor (7;

307;

407;

507, 607, 707, 807, 902), to form the said wheel, in such a way that the said sensor (7;

307;

407;

507, 607, 707, 807, 902) generates a continuous and cyclical signal indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically.

52. Method for monitoring the behaviour of a moving vehicle mounted on wheels that includes the following steps:

detecting a signal, which is generated continuously and cyclically by a sensor (7;

307;

407;

507, 607, 707, 807, 902) comprising an elongate piezoelectric element associated with at least one of the said wheels, and which is indicative of a state of mechanical stress or of its variations with respect to a previous state and detected continuously and cyclically,

transmitting the said signal to a processing unit (8) with which the said vehicle can be provided.

53. Method for controlling the behaviour of a moving vehicle mounted on wheels and comprising at least one motion control device that includes the following steps:

detecting a signal, which is generated continuously and cyclically by a sensor (7;

307;

407;

507, 607, 707, 807, 902) comprising an elongate piezoelectric element (10, 12;

20, 210) associated with at least one of the said wheels, the said signal being indicative of a state of mechanical stress or of its variations with respect to a previous state, detected continuously and cyclically;

transmitting the said signal to a unit (8) with which the said vehicle can be provided and which is capable of activating the said motion control device or devices.

54. Method for monitoring the structural uniformity of a tyre (1) by analysing the rotation, at a predetermined speed, of a wheel that includes the said tyre (1) inflated to a predetermined pressure and a mounting rim (15), of which both the mass and the relative distribution of the said mass are known, the said method including the following steps:

detecting a signal generated continuously and cyclically by a sensor (7;

307;

407;

507, 607, 707, 807, 902) comprising an elongate piezoelectric element (10, 12;

20, 210), associated with the said wheel, capable of sensing a cyclical variation of mechanical stress indicative of a variation of centrifugal force due to a nonuniformity of distribution of masses in the said wheel;

transmitting the said signal to a processing unit (8);

cleaning the said signal of the component due to the mounting rim (15);

comparing at least one distinctive element of the said signal with at least one reference value.

55. Method for detecting deflation of a tyre (1) by analysing the behaviour of the tyre (1) when moving with respect to a contact surface, that includes the following steps:

detecting a signal generated continuously and cyclically by a sensor (7;

307;

407;

507, 607, 707, 807, 902) comprising an elongate piezoelectric element (10, 12;

20, 210), associated with a wheel that includes the said tyre (1), the said signal being indicative of a state of mechanical stress or of its variations with respect to a previous state and being detected continuously and cyclically;

transmitting the said signal to a processing unit (8);

comparing at least one distinctive element of the said signal with at least one predetermined reference value;

indicating when the value found in this way departs from the said reference value.

56. Kit (900) for detecting the behaviour of a tyre (1) when moving with respect to a contact surface, the said tyre (1) and the said kit (900) both being mounted on a vehicle wheel rim (15);

in which the said kit (900) includes;

a sensor (7;

307;

407;

507, 607, 707, 807, 902) comprising an elongate piezoelectric element (10, 12;

20, 210) which, when placed in contact with a portion of the said tyre (1), comes under mechanical stress in relation to the movement of the tyre (1) and emits a continuous and cyclical signal indicative of variations of the said mechanical stress, detected continuously and cyclically and

a transmitter (39, 903) of the said continuous and cyclical signal.

57. Kit according to claim 56, characterized in that it also comprises a supporting structure (901).

58. Kit according to claim 56 or 57, characterized in that it also comprises an antenna (904).

59. Kit according to any one of claims 56 to 58, characterized in that it also comprises a receiver installable on the vehicle and tuned to the same frequencies as those at which the transmitter (39, 903) transmits.

60. Kit according to any one of the previous claims 56 to 59, characterized in that the said supporting structure (901) is of annular shape and is designed to be fitted onto the bead seat (32) of a mounting rim (15) for a tyre.

61. Kit according to claim 60, characterized in that the said supporting structure (901) can be laid between the shoulder (34) of the rim (15) and the outer surface of the tyre (1).

62. Kit according to claim 61, characterized in that the said supporting structure (901) can be laid between the shoulder (34) of the rim (15) and the outer surface of the bead area (5) of the tyre (1).

63. Method for monitoring at least one event correlated with the interaction between at least one tyre of a moving vehicle wheel and a surface of contact with the said tyre, comprising the following steps:

a) detecting at least one continuous and cyclical signal descriptive of the state of stress of the complete tyre and

b) processing the said signal or signals to obtain at least one numerical value representative of the magnitude of the said event or events.

64. Method according to claim 63, characterized in that, in the said step b), at least one spectrum of frequencies significant for the said event or events is extracted from the said signal or signals.

65. Method according to claim 64, characterized in that the said step of extracting at least one spectrum of frequencies includes a spectral frequency analysis of the said signal or signals using a Fourier transform.

66. Method according to claim 63, characterized in that the said step b) includes an RMS calculation.

67. Method according to claim 64, characterized in that the said RMS calculation is performed on the said spectrum over a range of significant frequencies.

68. Method according to claim 64, characterized in that the said RMS calculation is performed over a predetermined time interval within said signal.

69. Method according to any one of claims 63 to 68, characterized in that the said step b) includes comparing a plurality of distinctive elements of at least part of one cycle of the said signal or signals.

70. Method according to any one of claims 68 to 69, characterized in that the said step b) includes comparing a plurality of distinctive elements of at least part of one cycle with a corresponding plurality of distinctive elements of a previous cycle.

71. Method according to any one of claims 69 to 70, characterized in that the said step b) includes comparing the signals from at least one pair of tyres.

72. Method according to claim 63, characterized in that the said numerical value representative of the magnitude of the said event or events obtained in the said step b) is an index.

73. Method according to claim 72, characterized in that it includes comparing the said index with a predetermined reference value.

74. Method according to any one of claims 69 to 73, characterized in that the said predetermined reference value is selected from the following:

amplitudes of distinctive elements of at least a portion of at least one cycle of the said signal;

frequencies of distinctive elements of at least a portion of at least one cycle of the said signal; and

time intervals between distinctive elements of at least a portion of at least one cycle of the said signal and predetermined absolute values.

75. Method according to any one of claims 63 to 74, characterized in that the said signal or signals come from at least one sensor comprising an elongate piezoelectric element.