Miniaturized Piezoelectric Based Vibrational Energy Harvester

• US 20080136292A1
• Filed: 07/27/2005
• Published: 06/12/2008
• Est. Priority Date: 10/21/2004
• 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
• Granted Patent: US 7,692,366 B2
• Time in Patent Office: Days
• US Class Current: 310/334
• CPC Class Codes: B60C 23/041 Means for supplying power to the signal- transmitting means on the wheel
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/03 Assembling devices that include piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/304 Beam type
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

The present subject matter discloses apparatus and methodologies for fabricating apparatus for harvesting power from environmentally induced vibrations. Piezoelectric devices and structures (1600) are disclosed that employ constant force spring or flexure arrangements (1512) in balanced opposition configurations (1510, 1534) to enhance the power harvesting capabilities of the piezoelectric devices (1600). Power harvesting devices and systems in accordance with the subject technology may concurrently operate as sensors in motion sensitive applications thus providing self-powered monitoring capabilities.

Claims

1. An energy harvesting apparatus for harvesting and converting environmentally intrinsic vibrational energy into electrical energy comprising:

a constant force flexure structure;

at least one piezoelectric element secured to said constant force flexure structure;

a support structure securing at least one portion of said constant force flexure structure from relative motion along at least one axis; and

at least one proof mass coupled to a second portion of said constant force flexure structure;

whereby environmentally intrinsic vibrational energy produces relative movement between the proof mass and the support structure and consequent movement of the constant force flexure structure thereby producing electrical energy by said at least one piezoelectric element.

2. An energy harvesting apparatus as in claim 1, wherein said constant force flexure structure comprises at least one pair of constant force flexures.

3. An energy harvesting apparatus as in claim 2, wherein each of the flexures of the at least one pair of constant force flexures are arranged in balanced opposition to each other.

4. An energy harvesting apparatus as in claim 2, wherein said at least one proof mass is coupled to each of the flexures of the pair of constant force flexures.

5. An energy harvesting apparatus as in claim 2, further comprising:

at least one regenerative motion stop means wherein the motion stop means is configured to limit relative movement between the proof mass and the support structure in at least one axial direction.

6. An energy harvesting apparatus as in claim 5, wherein said at least one regenerative motion stop means comprises at least one pair of magnets.

7. An energy harvesting apparatus as in claim 2, further comprising:

at least two regenerative motion stop means wherein the motion stop means are configured to limit relative movement between the proof mass and the support structure in at least two axial directions.

8. An energy harvesting apparatus as in claim 7, wherein said at least two regenerative motion stop means comprises at least two pairs of magnets.

9. An energy harvesting apparatus as in claim 3, wherein a plurality of pairs of constant force flexures are arranged in balanced opposition to each other and at least one pair of piezoelectric elements are secured to at least one pair of the constant force flexures.

10. An energy harvesting apparatus as in claim 9, wherein a plurality of pairs of piezoelectric elements are secured to at least one of the constant force flexures and wherein each piezoelectric element of each of the plurality of pairs of piezoelectric elements is secured to opposite sides of at least one of said constant force flexures.

11. A double acting energy harvesting apparatus for harvesting and converting environmentally intrinsic vibrational energy into electrical energy comprising:

first and second constant force flexure structures, at least one of the constant force flexure structures comprising at least one constant force flexure supporting at least one piezoelectric element;

a longitudinally extending proof mass; and

a support frame surrounding said first and second constant force flexure structures and said longitudinally extending proof mass,

wherein a first portion of each constant force flexure structure is secured to opposite sides of said proof mass and a second end of each constant force flexure structure is secured to said support frame.

12. A double acting energy harvesting apparatus as in claim 11, further comprising at least one regenerative motion stop means couple to said proof mass and said support frame, wherein the motion stop means is configured to limit relative movement between the proof mass and support structure in at least one axial direction.

13. A double acting energy harvesting apparatus as in claim 12, wherein said motion stop means comprises at least one pair of magnets.

14. A double acting energy harvesting apparatus as in claim 11, wherein each constant force flexure structures comprise a plurality of constant force flexures, at least one of the constant force flexures supporting at least one piezoelectric element.

15. A double acting energy harvesting apparatus as in claim 14, wherein each of the plurality of constant force flexures each support a plurality of piezoelectric elements.

16. A double acting energy harvesting apparatus as in claim 15, wherein the plurality of piezoelectric elements are arranged in pairs on opposite sides of the constant force flexures to which they are attached.

17. A double acting energy harvesting apparatus as in claim 16, further comprising at least two regenerative motion stop means couple to said proof mass and said support frame, wherein the motion stop means is configured to limit relative movement between the proof mass and the support structure in at least two axial directions.

18. A double acting energy harvesting apparatus as in claim 17, wherein said motion stop means comprises at least two pairs of magnets.

19. A method for fabricating a double acting energy harvesting apparatus, comprising the steps of:

(a) fabricating a first half of the double acting energy harvesting apparatus by;

(1) providing a plurality of longitudinally extending flexures, each longitudinally extending flexure having first and second edges and first and second sides;

(2) securing one or more longitudinally extending piezoelectric elements to one or more of the sides of one or more of the longitudinally extending flexures;

(3) providing a U-shaped longitudinally extending frame;

(4) attaching the first edge of each of the plurality of longitudinally extending flexures to an interior surface of the U-shaped longitudinally extending frame; and

(5) attaching a first side of a common proof mass to the second edge of each of the plurality of longitudinally extending flexures;

(b) fabricating a second half of the double acting energy harvesting apparatus by repeating steps (1)-(5);

(c) coupling a second side of each of the proof masses of the first and second halves together;

(d) compressing the U-shaped longitudinally extending frame of the first half toward the U-shaped longitudinally extending frame of the second half until the open edges of the U-shaped longitudinally extending frames touch;

(e) joining the touching open edges of the U-shaped longitudinally extending frames to one another; and

(f) dicing the joined longitudinally extending frames into a plurality of longitudinally extending sections.

20. The method of claim 19, further comprising the steps of:

filling empty spaces within the joined U-shaped longitudinally extending frames with a sacrificial supporting material prior to the step of dicing; and

removing the sacrificial supporting material following the step of dicing.