Integrated self-powered tire revolution counter

• US 7,132,939 B2
• Filed: 07/07/2004
• Issued: 11/07/2006
• Est. Priority Date: 07/07/2004
• Status: Active Grant

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Tyndall, Patrick A., O'Brien, George Phillips, Tedrow, Timothy R.
• Primary Examiner(s): NGUYEN, HUNG T
• Application Number:
  US10/886,219
• Publication Number:
  US 20060006991A1
• Time in Patent Office: 853 Days
• Field of Search: 340/442, 340/444, 340/447, 340/448, 340/445, 340/446, 377/15, 377/16, 377/24.1, 701/1, 701/53, 731/46, 731/462, 731/468
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: B60C 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: G01C 22/00 Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers

Abstract

A self-powered tire revolution counter includes a motion sensitive power generation mechanism, a power conditioner, a pulse detector, a microcontroller, and, optionally, a radio frequency (RF) transmitting device. In one exemplary embodiment, the power generation mechanism corresponds to a piezoelectric patch that, during movement, provides both operating electrical power and pulsed signals indicative of tire rotation. The power conditioner receives a generator signal from the power generation mechanism and produces a conditioned output voltage that can be used to power associated electronic devices, including the microcontroller. The pulse detector receives the generator signal and produces a detection signal whenever the generator signal meets a predetermined condition. The microcontroller is programmed to determine current and lifetime-accumulated values of selected pulse indications in the detection signal that meet predetermined criteria. Data corresponding to tire environment related parameters such as temperature, pressure, tire deflection, and/or vehicle speed may be stored in the microcontroller at times during tire rotation as power is supplied from the power generation mechanism through the power conditioner. Additional data may be supplied to the microcontroller directly from an external source and read from the microcontroller either by direct electrical contact or via selective RF transmission.

Claims

1. A self-powered counter comprising:

a generator responsive to movement and configured to produce a generator output signal, said generator output signal being characterized by pulses indicative of said movement;

a power conditioner configured to receive said generator output signal and to produce a conditioned output voltage;

a pulse detector configured to receive said generator output signal and to produce a detection signal having respective pulse indications upon any received pulse from said generator meeting a first predetermined criteria; and

a microcontroller configured to receive operating power from said power conditioner and said detection signal from said pulse detector, said microcontroller further programmed to determine an accumulated value of selected pulse indications in said detection signal that meet a second predetermined criteria wherein the second predetermined criteria consists of meeting a predetermined time relationship between a predetermined number of successive pulses from said detection signal.

2. The self-powered counter of claim 1, wherein said generator comprises a piezoelectric device.

3. The self-powered counter of claim 1, wherein the first predetermined criteria is varied as a function of the output voltage of said power conditioner.

4. The self-powered counter of claim 1, wherein said microcontroller further comprises a circular buffer comprising at least n storage areas and wherein said microcontroller is further programmed so as to measure elapsed time between successive pulse indications from said pulse detector, to store n successive elapsed time measurements in said circular buffer, to compare a current elapsed time measurement (TC) to the maximum elapsed time measurement (TMAX) stored in said circular buffer, and to count as valid any pulse whose elapsed time measurement is greater than or equal to a predetermined fractional value of TMAX.

5. The self-powered counter of claim 4, wherein the predetermined fractional value of TMAX is TMAX/2.

6. The self-powered counter of claim 1, further comprising an RF transmission device coupled to said microcontroller for selectively relaying information stored in memory associated with said microcontroller to a remote location.

7. The self-powered counter of claim 1, further comprising at least one condition-responsive device for sensing environmental information related to temperature and/or pressure.

8. The self-powered counter of claim 1, wherein said microcontroller is further configured to determine revolution data relative to at least one secondary variable selected from the group consisting of temperature, pressure, time, and speed.

9. The self-powered counter of claim 1, further comprising a connection means coupled to said microcontroller for receiving information to be stored in memory associated with said microcontroller from a remote location.

10. A self-powered tire revolution counter, comprising:

a piezoelectric element responsive to tire rotation and configured to produce a generator output signal, said generator output signal being characterized by pulses indicative of said tire rotation;

a power conditioner configured to receive said generator output signal and to produce an output voltage;

a pulse detector configured to receive said generator output signal and to produce a detection signal having respective pulse indications upon any received pulse in said generator meeting a first predetermined criteria; and

a microcontroller configured to receive operating power from said power conditioner and the detection signal from said pulse detector, said microcontroller further programmed to determine an accumulated value of selected pulse indications in said detection signal that meet a second predetermined criteria wherein the second predetermined criteria consists of meeting a predetermined time relationship between a predetermined number of successive pulses from said detection signal.

11. The self-powered tire revolution counter of claim 10, wherein the first predetermined criteria is varied as a function of the output voltage of said power supply.

12. The self-powered tire revolution counter of claim 11, wherein said microcontroller further comprises a circular buffer comprising at least n storage areas and wherein said microcontroller is further programmed so as to measure elapsed time between successive signals from said pulse detector, to store n successive elapsed time measurements in said circular buffer, to compare a current elapsed time measurement (TC) to the maximum elapsed time measurement (TMAX) stored in said circular buffer, and to count as valid any pulse whose elapsed time measurement is greater than or equal to a predetermined fractional value of TMAX.

13. The self-powered tire revolution counter of claim 12, wherein said predetermined fractional value of TMAX is TMAX/2.

14. The self-powered tire revolution counter of claim 10, further comprising an RF transmitter coupled to said microcontroller for selectively relaying information stored in memory associated with said microcontroller to a remote location.

15. The self-powered tire revolution counter of claim 10, further comprising at least one condition responsive device for sensing information related to temperature and/or pressure.

16. The self-powered tire revolution counter of claim 10, wherein said microcontroller is further configured to determine tire revolution data relative to at least one secondary variable selected from the group consisting of temperature, pressure, time, speed, and tire deflection.

17. A pneumatic tire, comprising:

a tire structure characterized by a crown having an exterior tread portion, bead portions, exterior sidewall portions extending between each bead portion and the crown, and an inner liner along interior crown and sidewall surfaces; and

a self-powered tire revolution counter, comprising;

a generator responsive to tire rotation and configured to produce a generator output signal, said generator output signal being characterized by pulses indicative of said tire rotation;

a pulse detector configured to receive said generator output signal and to produce a detection signal having respective pulse indications upon any received pulse in said generator output signal meeting a first predetermined criteria; and

a microcontroller configured to receive the detection signal from said pulse detector, said microcontroller further programmed to determine an accumulated value of selected pulse indications in said detection signal that meet a second predetermined criteria wherein the second predetermined criteria consists of meeting a predetermined time relationship between a predetermined number of successive signals from said pulse generator.

18. The pneumatic tire of claim 17, wherein said generator comprises a piezoelectric device.

19. The pneumatic tire of claim 17, further comprising a power conditioner configured to receive said generator output voltage and to produce a conditioned output voltage for powering said microcontroller.

20. The pneumatic tire of claim 19, wherein the first predetermined criteria is varied as a function of the output voltage of said power supply.

21. The pneumatic tire of claim 17, wherein said microcontroller further comprises a circular buffer comprising n storage areas and wherein said microcontroller is further programmed so as to measure elapsed time between successive signals from said pulse detector, to store n successive elapsed time measurements in said circular buffer, to compare a current elapsed time measurement to the maximum elapsed time measurement (TMAX) stored in said circular buffer, and to count as valid any pulse whose elapsed time measurement is greater than or equal to TMAX/2.

22. The pneumatic tire of claim 17, wherein the self-powered tire revolution counter is secured to the inner liner of the tire.

23. The pneumatic tire of claim 17, wherein the self-powered tire revolution counter is cured within the tire structure.

24. A method for counting completed revolutions of a rotating element, the method comprising the steps of:

providing a generator configured to produce a signal pulse upon detection of a repeating predetermined condition;

measuring the elapsed time between first and second signal pulses to produce a current measured time value;

storing the current measured time value;

comparing the current measured time value with a predetermined fraction of a previously stored measured time value;

counting a detected pulse as representing a completed rotation if the current measured time value is greater than or equal to the predetermined fraction of a previously stored measured time value; and

repeating the steps of measuring, storing, comparing and counting to accumulate a total revolutions count for the rotating element.

25. The method of claim 24, wherein the step of comparing is applied to a predetermined fraction of the maximum time value of a predetermined most recent number of stored measured time values.

26. The method of claim 25, wherein the step of comparing is applied to a value of one half of the maximum time value of the predetermined most recent number of stored measured time values.

27. The method of claim 26, wherein the predetermined most recent number of stored measured time values is set equal to six.

28. The method of claim 24, wherein the current measured time value is stored in a circular buffer.