Tire monitoring apparatus and method

• US 5,231,872 A
• Filed: 02/21/1991
• Issued: 08/03/1993
• Est. Priority Date: 02/21/1991
• Status: Expired due to Term

• Current Assignee: Smartire Systems Incorporated (TTC Technology Corp.)
• Original Assignee: TTC Truck Tech Corporation
• Inventors: Mackay, John, Fulton, Robert H., Bowler, Paul R., Lammers, Shawn D.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US07/658,025
• Time in Patent Office: 894 Days
• Field of Search: 73/146.5, 73/146.8, 375/143, 116/34 R, 340/442, 340/445, 340/447, 340/858, 340/859
• US Class Current: 73/146.5
• CPC Class Codes: B60C 23/007 having multiple wheels arranged side by side
• CPC Class Codes: B60C 23/008 having wheels on more than two axles
• CPC Class Codes: B60C 23/009 having wheels on a trailer
• CPC Class Codes: B60C 23/0401 characterised by the type of alarm
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B60C 23/0445 Means for changing operating mode, e.g. sleep mode, factory mode or energy saving mode
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: B60C 23/0474 Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring

Abstract

A method and apparatus for measuring a physical quantity, property or condition and for transmitting a code representing the measured physical quantity, property or condition. The method includes the steps of developing a first signal in response to a physical quantity, property or condition, sampling the first signal to produce an instantaneous first signal value, assigning a first code to the instantaneous first signal value, and transmitting the first code for reception by a receiver. The method and apparatus are explained in connection with a vehicle tire monitoring apparatus wherein plurality of tire units measure tire pressures and temperatures and transmit values representing pressure and temperature to a central receiver located in a cab portion of the vehicle.

Claims

1. A method of measuring and transmitting, the method including the steps of:

(a) developing a first signal in response to a physical quantity, property or condition;

(b) sampling said first signal to produce an instantaneous first signal value;

(c) encoding said instantaneous first signal value by assigning a first code to said instantaneous first signal value; and

(d) transmitting a transmission for reception by a receiver, said transmission including;

(i) said first code;

(ii) an identification code identifying said physical quantity, property or condition such that said identification code enables said transmission to be distinguished from other similar transmissions received by the same receiver; and

(iii) a plurality of receiver resynchronization codes for resynchronizing a receiver receiving the transmission.

2. A method as claimed in claim 1, wherein the step of sampling includes:

(a) testing said signal to determine whether it meets a first or second set of conditions;

(b) sampling said signal at a first rate when said signal meets said first set of conditions; and

(c) sampling said signal at a second rate when said signal meets said second set of conditions.

3. A method as claimed in claim 2, wherein the step of testing includes:

(a) comparing a later acquired first code with an earlier acquired first code;

(b) meeting said first set of conditions when said later acquired first code is within a pre-defined range of said earlier acquired first code; and

(c) meeting said second set of conditions when said later acquired first code is outside a pre-defined range of said earlier acquired first code.

4. A method as claimed in claim 2, wherein the step of testing includes:

(a) determining a rate of change of said first signal;

(b) meeting said first set of conditions when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change; and

(c) meeting said second set of conditions when said rate of change of said first signal is outside a pre-defined range of a pre-defined rate of change.

5. A method as claimed in claims 2 or 3 or 4, wherein the step of sampling includes sampling with said first rate being less than said second rate.

6. A method as claimed in claim 1, wherein the step of transmitting includes transmitting a later acquired first code at first regular intervals of time.

7. A method as claimed in claim 6, wherein the step of transmitting includes:

(a) testing said signal to determine whether or not said signal meets a first or second set of conditions;

(b) transmitting at said first regular intervals of time when said first signal meets said first set of conditions; and

(c) transmitting at second regular intervals of time when said first signal meets said second set of conditions.

8. A method as claimed in claim 7, wherein the step of testing includes:

(a) comparing the later acquired first code with an earlier acquired first code;

(b) meeting said first set of conditions when said later acquired first code is within a pre-defined range of said earlier acquired first code; and

(c) meeting said second set of conditions when said later acquired first code is outside of pre-defined range of said earlier acquired first code.

9. A method as claimed in claim 7, wherein the step of transmitting includes:

(a) determining a rate of change of said first signal;

(b) meeting said first set of conditions when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change; and

(c) meeting said second set of conditions when said rate of change of said first signal is outside a pre-defined range of a pre-defined rate of change.

10. A method as claimed in claims 7, 8 or 9, wherein the step of transmitting at said first regular intervals of time includes the step of making said first regular intervals of time longer than said second regular intervals of time.

11. A method as claimed in claim 1, wherein the step of encoding includes the step of converting said instantaneous first signal into a binary code.

12. A method as claimed in claim 1, wherein the step of developing said first signal includes employing a temperature transducer to develop said first signal in response to temperature.

13. A method as claimed in claim 1, wherein the step of developing includes employing a temperature transducer to develop said first signal in response to air temperature in a tire.

14. A method as claimed in claim 1, wherein the step of developing includes employing a pressure transducer to develop said first signal in response to pressure.

15. A method as claimed in claim 1, wherein the step of developing includes employing a pressure transducer to develop said first signal in response to air pressure in a tire.

16. An apparatus for measuring and transmitting, the apparatus including:

(a) a transducer for developing a first signal in response to a physical quantity, property or condition;

(b) sampling means for sampling said first signal to produce an instantaneous first signal value;

(c) encoding means for assigning a first code representative of said instantaneous first signal value; and

(d) transmitting means for transmitting a transmission to a receiver, said transmission including;

(i) said first code;

(ii) an identification code identifying said physical quantity, property or condition such that said identification code enables said transmission to be distinguished from other similar transmissions received by the same receiver; and

(iii) a plurality of receiver resynchronization codes for resynchronizing a receiver receiving the transmission.

17. An apparatus as claimed in claim 16, wherein the sampling means includes:

testing means for testing said signal to determine whether it meets a first or second set of conditions and for sampling said signal at a first rate when said signal meets said first set of conditions and for sampling said signal at a second rate when said signal meets said second set of conditions.

18. An apparatus as claimed in claim 17, wherein the testing means includes:

comparing means for comparing a later acquired first code with an earlier acquired first code and wherein said first set of conditions are met when said later acquired first code is within a pre-defined range of said earlier acquired first code and wherein said second set of conditions are met when said later acquired first code is outside of a pre-defined range of said earlier acquired first code.

19. An apparatus as claimed in claim 17, wherein the testing means includes:

determining means for determining a rate of change of said first signal and wherein said first set of conditions are met when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change and wherein said second set of conditions are met when said rate of change of said first signal is outside a pre-defined range of a pre-defined rate of change.

20. An apparatus as claimed in claims 17, 18 or 19, wherein the first sampling rate is less than the second sampling rate.

21. An apparatus as claimed in claim 16, wherein the transmitting means is for transmitting a later acquired first code at first regular intervals of time.

22. An apparatus as claimed in claim 21, wherein the transmitting means includes:

testing means for testing said signal to determine whether or not said signal meets a first or second set of conditions and for transmitting at said first regular intervals of time when said first signal meets said first set of conditions an for transmitting at second regular intervals of time when said first signal meets said second set of conditions.

23. An apparatus as claimed in claim 22, wherein the testing means includes:

comparing means for comparing a later acquired first code with an earlier acquired first code and wherein said first set of conditions are met when said later acquired first code is within a pre-defined range of said earlier acquired first code and wherein said second set of conditions are met when said later acquired first code is outside of a pre-defined range of said earlier acquired first code.

24. An apparatus as claimed in claim 22, wherein the transmitting means includes:

determining means for determining a rate of change of said first signal and wherein said first set of conditions are met when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change and wherein said second set of conditions are met when said rate of change of said first signal is outside of a pre-defined range of a pre-defined rate of change.

25. An apparatus as claimed in claims 22 or 23 or 24, wherein the first regular intervals of time are longer than said second regular intervals of time.

26. An apparatus as claimed in claim 16, wherein the encoding means performs an analog-to-digital conversion on said instantaneous first signal to produce a binary first code.

27. An apparatus as claimed in claim 16, wherein the transducer includes a temperature transducer for developing said first signal in response to temperature.

28. An apparatus as claimed in claim 16, wherein the transducer includes a temperature transducer for developing said first signal in response to air temperature in a tire.

29. An apparatus as claimed in claim 16, wherein the transducer includes a pressure transducer for developing said first signal in response to pressure.

30. An apparatus as claimed in claim 16, wherein the transducer includes a pressure transducer for developing said first signal in response to air pressure in a tire.

31. An apparatus for measuring and transmitting an operating parameter of a tire, the apparatus including:

(a) a pneumatic tire;

(b) a transducer for developing a first signal in response to air pressure or air temperature within said tire;

(c) sampling means for sampling said first signal to produce an instantaneous first signal value;

(d) encoding means for assigning a first code to said instantaneous first signal value; and

(e) transmitting means for transmitting a transmission to a receiver, said transmission including;

(i) said first code;

(ii) an identification code identifying said physical quantity, property or condition such that said identification code enables said transmission to be distinguished from other similar transmissions received by the same receiver; and

(iii) a plurality of receiver resynchronization codes for resynchronizing a receiver receiving the transmission.

32. An apparatus as claimed in claim 31, wherein the sampling means includes:

testing means for testing said signal to determine whether it meets a first or second set of conditions and for sampling said signal at a first rate when said signal meets said first set of conditions and for sampling said signal at a second rate when said signal meets said second set of conditions.

33. An apparatus as claimed in claim 32, wherein the testing means includes:

comparing means for comparing a later acquired first code with an earlier acquired first code and wherein said first set of conditions are met when said later acquired first code is within a pre-defined range of said earlier acquired first code and wherein said second set of conditions are met when said later acquired first code is outside of a pre-defined range of said earlier acquired first code.

34. An apparatus as claimed in claim 32, wherein the testing means includes:

determining means for determining a rate of change of said first signal and wherein said first set of conditions are met when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change and wherein said second set of conditions are met when said rate of change of said first signal is outside of a pre-defined range of a pre-defined rate of change.

35. An apparatus as claimed in claims 32 or 33 or 34, wherein the first rate is less than the second rate.

36. An apparatus as claimed in claim 31, wherein the transmitting means is for transmitting a later acquired first code at first regular intervals of time.

37. An apparatus as claimed in claim 36, wherein the transmitting means includes:

testing means for testing said signal to determine whether or not said signal meets a first or second set of conditions and for transmitting at said first regular intervals of time when said first signal meets said first set of conditions, and for transmitting at second regular intervals of time when said first signal meets said second set of conditions.

38. An apparatus as claimed in claim 37, wherein the testing means includes:

comparing means for comparing a later acquired first code with an earlier acquired first code and wherein said first set of conditions are met when said later acquired first code is within a pre-defined range of said earlier acquired first coded and wherein said second set of conditions are met when said later acquired first code is outside a pre-defined range of said earlier acquired first code.

39. An apparatus as claimed in claim 37, wherein the transmitting means includes:

determining means for determining a rate of change of said first signal and wherein said first set of conditions are met when said rate of change of said signal is within a pre-defined range of a pre-defined rate of change, and wherein said second set of conditions are met when said rate of change of said first signal is outside of a pre-defined range of a pre-defined rate of change.

40. An apparatus as claimed in claims 37 or 38 or 39, wherein the first regular intervals of time are longer than said second regular intervals of time.

41. An apparatus as claimed in claim 31, wherein the encoding means performs an analog-to-digital conversion on said instantaneous first signal to produce a binary first code.

42. An apparatus as claimed in claim 31, wherein the transducer includes a temperature transducer for developing said first signal in response to temperature.

43. An apparatus as claimed in claim 42, wherein the temperature transducer is external to the tire.

44. An apparatus as claimed in claim 31, wherein the transducer includes a pressure transducer for developing said first signal in response to pressure.

45. An apparatus as claimed in claim 44, wherein the pressure transducer is external to the tire.

46. An apparatus for measuring and transmitting an operating parameter of a tire, the apparatus comprising:

(a) a body having connecting means for connecting said body to a valve stem of a tire and a chamber pressurized by air from said tire;

(b) measuring means for measuring an instantaneous value of at least one operating parameter in said chamber, the measuring means including sampling means for automatically sampling said instantaneous value of said at least one operating parameter at regular intervals in time to produce a first code representative of said instantaneous value; and

(c) transmitting means for transmitting a transmission to a receiver, said transmission including;

(i) said first code;

(ii) an identification code identifying said physical quantity, property or condition such that said identification code enables said transmission to be distinguished from other similar transmissions received by the same receiver; and

(iii) a plurality of receiver resynchronization codes for resynchronizing a receiver receiving the transmission.

47. An apparatus as claimed in claim 46 wherein the body has a conduit therein, the conduit having first and second openings, the first opening being connectable to the valve stem, and the second opening having a valve member mounted thereto to permit air to be forced into the tire while preventing air from escaping from said tire.

48. An apparatus as claimed in claim 47 wherein the conduit is in communication with the chamber.

49. An apparatus as claimed in claim 46 wherein the transmitting means includes an antenna.

50. An apparatus as claimed in claim 46 further including pressure measurement means for measuring the pressure of air in said tire.

51. An apparatus as claimed in claim 50 wherein said pressure measurement means includes a pressure sensor having a voltage which varies in response to air pressure in said chamber.

52. An apparatus as claimed in claim 50 wherein said transmitting means transmits a representation of said pressure in said tire.