System and method for generating electric power from a rotating tire's mechanical energy using piezoeletric fiber composites

• US 20030209063A1
• Filed: 05/10/2002
• Published: 11/13/2003
• Est. Priority Date: 05/10/2002
• 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: Adamson, John D., OʼBrien, George P.
• Granted Patent: US 6,807,853 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: B60K 25/08 from a ground wheel, e.g. engaging the wheel tread or rim
• CPC Class Codes: B60K 25/10 directly from oscillating movements due to vehicle running motion, e.g. suspension movement resilient suspensions having dampers accumulating utilisable energy, e.g. compressing air, B60G13/14

Abstract

A system and corresponding method for generating electric power from a rotating tire'"'"'s mechanical energy concerns a power generation device with a piezoelectric structure and a power conditioning module. The piezoelectric structure preferably comprises a plurality of piezoelectric fibers embedded in a generally unidirectional fashion within an epoxy matrix. Such piezoelectric structure additionally comprises interdigital electrode layers on opposing sides of the fiber/epoxy matrix configuration. The piezoelectric structure is preferably mounted within a tire structure such that electric charge is generated therein as the wheel assembly moves along a ground surface. Electrode layers within the piezoelectric structure are coupled to a power conditioning module that rectifies the resultant electric current from the piezoelectric structure and stores it in an energy storage device, preferably an electrolytic capacitor. A rechargeable battery may also be provided for storing additional charge generated within the piezoelectric structure. A regulated voltage source is provided from the energy stored in the power generation device and can be used to power various electronics systems integrated within a tire or wheel assembly. An example of an integrated tire electronics system for use with the disclosed power generation device corresponds to a tire monitoring system that wirelessly transmits such information as tire pressure, temperature and identification variables to a remote receiver location.

Claims

1. A pneumatic tire assembly with integrated self-powered electronic components, said tire assembly comprising:

a tire structure characterized by a crown having an exterior tread portion for making contact with a ground surface, bead portions for seating said tire to a wheel rim, exterior sidewall portions extending between each bead portion and the crown, and interior crown and sidewall surfaces;

an active piezoelectric fiber composite structure integrated with a selected interior portion of said tire structure;

a power conditioning module electrically coupled to said piezoelectric fiber composite structure for receiving electric energy generated therein and for generating a regulated voltage output; and

an electronics package connected to said power conditioning module such that selected functionality of said electronics package is powered by the regulated voltage output.

2. A pneumatic tire as in claim 1, further including a rubber casing provided adjacent to and covering exposed portions of said piezoelectric fiber composite structure and said power conditioning module and for facilitating the adhesion of said piezoelectric fiber composite structure to a selected portion of the interior crown and sidewall surfaces of said tire structure.

3. A pneumatic tire as in claim 1, wherein said active piezoelectric fiber composite structure comprises a plurality of piezoelectric fibers embedded in an epoxy matrix layered on either side by etched electrode layers.

4. A pneumatic tire as in claim 3, wherein said piezoelectric fibers comprise a lead zirconate titanate (PZT) material selected from the group consisting of PZT 5H, PZT 5A, PZT 4, and PZT 8.

5. A pneumatic tire as in claim 3, wherein each etched electrode layer comprises an interdigital configuration of opposing electrode fingers with a predetermined pitch between adjacent electrode fingers.

6. A pneumatic tire as in claim 3, wherein the piezoelectric fibers of said piezoelectric fiber composite structure are all aligned in a generally unidirectional fashion and mounted radially with respect to the interior crown surface of said tire structure.

7. A pneumatic tire as in claim 3, wherein the piezoelectric fibers of said piezoelectric fiber composite structure are all aligned in a generally unidirectional fashion and mounted circumferentially with respect to the interior crown surface of said tire structure.

8. A pneumatic tire as in claim 1, wherein said power conditioning module comprises a voltage rectifier for rectifying the electric current signal generated within the piezoelectric fiber composite structure, an energy storage device for storing the energy provided in the rectified electric current signal, and a voltage regulator for generating the regulated voltage output.

9. A pneumatic tire as in claim 8, wherein said voltage rectifier is a full bridge rectifier and wherein said energy storage device is an electrolytic capacitor.

10. A pneumatic tire as in claim 1, wherein said electronics package comprises sensors to determine the pressure and temperature within said pneumatic tire, a microcontroller with associated memory and A/D converter for processing information determined by said sensors, and a radio frequency (RF) transmitter for relaying selected sensor information and additional tire identification information to a remote location.

11. A pneumatic tire as in claim 10, further comprising a rechargeable battery for storing energy generated by said piezoelectric fiber composite structure for providing an alternate power source to said electronics package.

12. A tire monitoring system for integration with a pneumatic tire structure designed to measure and transmit information relating to preselected tire conditions, said tire monitoring system comprising:

an active piezoelectric fiber composite structure integrated in the pneumatic tire structure, wherein said piezoelectric fiber composite structure is characterized by a plurality of piezoelectric fibers embedded in an epoxy matrix and provided between at least two electrode layers;

a power conditioning module electrically coupled to selected electrode layers of said piezoelectric fiber composite structure for receiving electric charge generated within the piezoelectric fiber, for storing the charge in an energy storage device within the power conditioning module, and for generating a regulated voltage output;

a plurality of sensors for determining information about preselected tire conditions, wherein said sensors are powered by the regulated voltage output from said power conditioning module;

a microcontroller connected to said power conditioning module and to said plurality of sensors for processing the information received from said sensors, and for generating select information indicative of preselected tire conditions; and

an RF transmitter electrically connected to said microcontroller for receiving select information from said microcontroller, modulating the select information to a carrier signal, and transmitting the select information to a remote receiver location.

13. A tire monitoring system as in claim 12, wherein the electrode layers of said piezoelectric fiber composite structure comprise respective configurations of interdigital electrode fingers.

14. A tire monitoring system as in claim 13, wherein the pitch between interdigital electrode fingers is about forty-five thousandths of an inch (mils).

15. A tire monitoring system as in claim 12, wherein the plurality of piezoelectric fibers are mounted in a generally parallel and unidirectional fashion.

16. A tire monitoring system as in claim 12, wherein the piezoelectric fibers of said piezoelectric fiber composite structure comprise the lead zirconate titanate (PZT) material known as PZT-5A.

17. A tire monitoring system as in claim 12, wherein said power conditioning module comprises a voltage rectifier for rectifying the electric signal generated within said piezoelectric fiber composite structure, an energy storage device for storing the energy provided in the electric signal, and a voltage regulator for generating the regulated voltage output.

18. A tire monitoring system as in claim 17, wherein said voltage rectifier is a full bridge rectifier and wherein said energy storage device is an electrolytic capacitor.

19. A tire monitoring system as in claim 17, wherein the regulated output voltage is at a level of about five volts.

20. A tire monitoring system as in claim 12, wherein selected of said plurality of sensors provide information about the temperature and pressure within a pneumatic tire structure.

21. A tire monitoring system as in claim 20, wherein the select information generated by said microcontroller is indicative of the temperature and pressure of the tire structure, the number of tire revolutions that the tire structure has been subjected to, and a tire identification tag.

22. A method for generating power from piezoelectric materials integrated within a wheel assembly, said method comprising the following steps:

providing an active piezoelectric fiber composite structure, wherein said active piezoelectric tire structure is characterized by a plurality of unidirectional piezoelectric fibers embedded in an epoxy matrix and provided between active electrode layers, and wherein said piezoelectric fiber composite structure is positioned along a selected location within the interior of the wheel assembly;

subjecting the wheel assembly to mechanical strain generally occurring as the wheel assembly rotates along a ground surface resulting in flexure of portions of the wheel assembly and generation of electric current within the provided piezoelectric fiber composite structure;

conditioning the electric current generated within the piezoelectric fiber composite structure; and

storing the conditioned electric current in an energy storage device such that a regulated voltage source is available for powering electronic devices associated with the wheel assembly.

23. A method for generating power as in claim 22, wherein said conditioning step comprises rectifying the electric current generated within the piezoelectric fiber composite structure.

24. A method for generating power as in claim 22, further comprising the step of selectively providing a regulated voltage source from the stored and conditioned electric current to a microcontroller additionally provided within the wheel assembly.

25. A method for generating power as in claim 22, further comprising the step of providing a rechargeable battery for storing electric current generated within the provided piezoelectric fiber composite structure.