Piezoelectric ceramic fibers having metallic cores

• US 20050274176A1
• Filed: 06/10/2004
• Published: 12/15/2005
• Est. Priority Date: 06/10/2004
• 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: Thiesen, Jack, Adamson, John David
• Granted Patent: US 7,047,800 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/30 with mechanical input and electrical output, e.g. functioning as generators or sensors
• CPC Class Codes: H10N 30/60 having a coaxial cable structure

Abstract

An enhanced piezoelectric wire structure includes an elongated portion of piezoelectric material, a metallic core, and an outer conductive sheath. The metallic core is substantially surrounded by the elongated portion of piezoelectric material and configured to function as a first electrode for the piezoelectric structure. The conductive outer sheath preferably covers selected areas of the elongated portion of piezoelectric material and functions as a second electrode for the structure. The piezoelectric material may correspond to barium titanate ceramic fibers, such that a lead-free structure is effected, however other piezoelectric materials may also be utilized. The disclosed structure can be poled with a reduced poling voltage and lower temperature level, and also requires a reduced voltage potential level required for mechanical actuation. A collection of such piezoelectric structures can be provided together in a modular patch assembly that may be formed in a variety of customized configurations for integration with various environments, and can function as a mechanical actuator device, a condition-responsive device (e.g., a sensor) and/or as a power generation device. When utilized as a power generation device, the subject piezoelectric assembly can power tire electronics components such as a revolution counter, a sensor, a rechargeable battery, a flashing light assembly, a microcontroller, a global positioning system (GPS), and a radio frequency (RF) device.

Claims

1. A power generation device, comprising:

a modular patch of piezoelectric material configured to generate an electric charge therein upon said power generation device being subjected to mechanical vibrations, said modular patch comprising;

a plurality of elongated piezoelectric structures;

a plurality of metallic cores, each metallic core substantially surrounded by one of said plurality of elongated piezoelectric structures, wherein the collective plurality of metallic cores is configured to function as a first electrode for the modular patch of piezoelectric material; and

conductive material encompassing each of said plurality of elongated piezoelectric structures and forming a common second electrode for the modular patch of piezoelectric material; and

an energy storage device configured to receive said electric charge from said modular patch of piezoelectric material and to store selected amounts of said electric charge therein.

2. The power generation device of claim 1, wherein said plurality of piezoelectric structures comprise barium titanate fibers.

3. The power generation device of claim 1, wherein said piezoelectric structures comprise a material selected from the group consisting of quartz, barium titanate, cadmium sulfide, lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC).

4. The power generation device of claim 1, further comprising means for monitoring the amount of electric charge generated by said modular patch of piezoelectric material to determine preselected characteristics of a pneumatic tire structure.

5. The power generation device of claim 4, wherein said predetermined characteristics are selected from the group consisting of temperature, pressure, number of tire revolutions, vehicle speed, and level of static and dynamic forces acting on a tire structure.

6. The power generation device of claim 1, wherein said modular patch of piezoelectric material is integrated with a selected portion of a pneumatic tire structure and is configured to generate an electric charge therein upon said pneumatic tire structure being subjected to mechanical strains.

7. The power generation device of claim 1, further comprising means for monitoring the electric charge generated by said modular patch of piezoelectric material to determine when poling effectiveness of the piezoelectric structures falls below a predetermined threshold level.

8. The power generation device of claim 7, further comprising a power source coupled to respective first and second electrodes of said modular patch for repoling the modular patch of piezoelectric material when device effectiveness falls below said predetermined threshold level.

9. The power generation device of claim 1, further comprising at least one electronic component selected from the group consisting of a revolution counter, a condition-responsive device, a rechargeable battery, a flashing light assembly, a microcontroller, a global positioning system (GPS), and a radio frequency (RF) device, and wherein said at least one electronic component is powered by the electric charge generated in said modular patch of piezoelectric material.

10. The power generation device of claim 1, wherein said energy storage device comprises one of an electrolytic capacitor, a super capacitor, a rechargeable solid-state battery, and a rechargeable chemical battery.

11. An electronics assembly, comprising:

at least one piezoelectric wire structure, said at least one piezoelectric wire structure comprising;

an elongated portion of piezoelectric material;

a metallic core substantially surrounded by said elongated portion of piezoelectric material, said metallic core configured to function as a first electrode for the piezoelectric structure; and

a conductive outer sheath covering selected areas of said elongated portion of piezoelectric material, said conductive outer sheath configured to function as a second electrode for the piezoelectric structure; and

a microcontroller coupled to said at least one piezoelectric wire structure for monitoring amounts of electric charge generated by or provided to said at least one piezoelectric wire structure.

12. The electronics assembly of claim 11, wherein said piezoelectric material comprises barium titanate fibers.

13. The electronic assembly of claim 11, wherein said piezoelectric material comprises a material selected from the group consisting of quartz, barium titanate, cadmium sulfide, lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC)

14. The electronics assembly of claim 11, wherein said at least one piezoelectric wire structure is adapted to operate as a condition-responsive device to monitor predetermined characteristics of a given environment by generating varied amounts of electric charge relative to the predetermined characteristics.

15. The electronics assembly of claim 14, wherein said predetermined characteristics are selected from the group consisting of temperature, pressure, and level of static and dynamic forces acting on said given environment.

16. The electronics assembly of claim 11, wherein said at least one piezoelectric wire structure is integrated with a selected portion of a pneumatic tire structure and is configured to sense at least one predetermined characteristic selected from the group consisting of temperature, pressure, number of tire revolutions, vehicle speed, and level of static and dynamic forces acting on said pneumatic tire structure.

17. The electronics assembly of claim 11, further comprising means for controlling said piezoelectric structure as a mechanical actuator device.

18. The electronics assembly of claim 11, wherein said at least one piezoelectric wire structure is oriented in a two-dimensional sinusoidal configuration.

19. The electronics assembly of claim 11, wherein said at least one piezoelectric wire structure is oriented in a three-dimensional helical configuration.

20. The electronics assembly of claim 11, wherein said metallic core substantially surrounded by said elongated portion of piezoelectric material is formed by co-extrusion.

21. The electronics assembly of claim 11, wherein said elongated portion of piezoelectric material is formed around said metallic core by one of dipping, spraying, or employing plasma deposition.

22. The electronics assembly of claim 11, further comprising a radio frequency (RF) device coupled to and controlled by said microcontroller for communicating signals output by or for input to said at least one piezoelectric wire structure.

23. A tire assembly with integrated power generation features, said tire assembly comprising:

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

a modular patch of piezoelectric material integrated with a select portion of said pneumatic tire structure, said modular patch configured to generate an electric charge therein upon said pneumatic tire structure being subjected to mechanical strains, said modular patch including;

a plurality of elongated piezoelectric structures,

a plurality of metallic cores, each metallic substantially surrounded by one of said plurality of elongated piezoelectric structures, wherein the collective plurality of metallic cores is configured to function as a first electrode for the modular patch of piezoelectric material, and

conductive material encompassing each of said plurality of elongated piezoelectric structures and forming a common second electrode for the modular patch of piezoelectric wire structures.

24. The tire assembly of claim 23, wherein the piezoelectric structures in said modular patch comprise a material selected from the group consisting of quartz, barium titanate, cadmium sulfide, lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC).

25. The tire assembly of claim 23, further comprising means for monitoring the amount of electric charge generated in said modular patch to determine predefined characteristics of a pneumatic tire structure.

26. The tire assembly of claim 25, wherein said predetermined characteristics are selected from the group consisting of temperature, pressure, number of tire revolutions, vehicle speed, and level of static and dynamic forces acting on a tire structure.

27. The tire assembly of claim 23, further comprising an energy storage device configured to receive the electric charge generated in said modular patch of piezoelectric material and to store selected amounts of electric charge therein.

28. The tire assembly of claim 27, wherein said energy storage device comprises a device selected from the group consisting of an electrolytic capacitor, a non-electrolytic capacitor, a super capacitor, a rechargeable solid-state battery, and a rechargeable chemical battery.

29. The tire assembly of claim 23, further comprising means for monitoring the electric charge generated by said modular patch of piezoelectric material to determine when the poling effectiveness of the piezoelectric structures falls below a predetermined threshold level.

30. The tire assembly of claim 29, further comprising a power source coupled to respective first and second electrodes of said modular patch for repoling the modular patch of piezoelectric material when device effectiveness falls below said predetermined threshold level.

31. The tire assembly of claim 23, further comprising at least one electronic component selected from the group consisting of a revolution counter, a condition-responsive device, a rechargeable battery, a flashing light assembly, a microcontroller, a global positioning system (GPS) and a radio frequency (RF) device, and wherein said at least one electronic component is powered by the electric charge generated in said modular patch of piezoelectric material.

32. The tire assembly of claim 23, further comprising a support substrate, wherein said modular patch is embedded in said support substrate.

33. A method for generating power from piezoelectric materials integrated with a vibrational system, said method comprising the following steps:

providing at least one piezoelectric wire structure at a selected location relative to the vibrational system, wherein said at least one piezoelectric wire structure is characterized by an elongated portion of piezoelectric material configured with an inner electrode and an outer electrode;

subjecting said at least one piezoelectric wire structure to mechanical strains associated with the vibrational system such that electric charge is generated within said at least one piezoelectric wire structure; and

storing selected amounts of the electric charge generated in said at least one piezoelectric wire structure such that said stored electric charge is available for powering electronic devices associated with said vibrational system.

34. The method of claim 33, further comprising the step of conditioning the flow of electric charge generated in said at least one piezoelectric wire structure before said storing step.

35. The method of claim 33, further comprising the step of providing a regulated voltage source from the stored electric charge to a microcontroller additionally coupled to said vibrational system.

36. The method of claim 33, wherein said vibrational system comprises a tire or wheel assembly and wherein the mechanical strains of said subjecting step associated with the vibrational system correspond to mechanical strains generally occurring as the tire or wheel assembly rotates along a ground surface.