Adjustable resonance frequency vibration power harvester

• US 20090195222A1
• Filed: 02/06/2008
• Published: 08/06/2009
• Est. Priority Date: 02/06/2008
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Lu, Liang-Ju, Hedtke, Robert
• Granted Patent: US 7,812,466 B2
• Time in Patent Office: Days
• US Class Current: 322/3
• CPC Class Codes: H02N 2/188 adapted for resonant operation

Abstract

A resonance frequency vibration power harvester comprises an elongate body, a first vibration energy harvester device and a weight. The elongate body includes a first end, a second end and an interior channel extending through at least a portion of the elongate body between the first end and the second end. The second end of the elongate body is for connecting to a vibration source such that the first end is cantilevered. The first vibration energy harvester device is attached adjacent the first end of the elongate body, and the weight is joined to the interior channel to adjust a resonant frequency of the elongate body.

Claims

1. A resonance frequency vibration power harvester comprising:

an elongate body having;

a first end;

a second end for connection to a vibration source such that the first end is cantilevered; and

an interior channel extending through at least a portion of the elongate body between the first end and the second end;

a first vibration energy harvester device attached adjacent the first end of the elongate body; and

a weight joined to the interior channel to adjust a resonant frequency of the elongate body.

2. The resonance frequency vibration power harvester of claim 1 wherein the weight is joined to the interior channel using a threaded fastener such that the first weight is positioned outside the elongate body.

3. The resonance frequency vibration power harvester of claim 1 wherein the weight comprises an elongate threaded cylinder for traversing threaded engagements in the interior channel.

4. The resonance frequency vibration power harvester of claim 3 wherein the elongate threaded cylinder extends from the interior channel to increase overall length of the elongate body.

5. The resonance frequency vibration power harvester of claim 3 wherein the elongate threaded cylinder further includes graduated markings.

6. The resonance frequency vibration power harvester of claim 1 wherein the weight comprises a first threaded set screw for traversing threaded engagements in the interior channel.

7. The resonance frequency vibration power harvester of claim 6 wherein the threaded set screw is recessed within the interior channel to adjust midspan mass of the elongate body.

8. The resonance frequency vibration power harvester of claim 6 and further comprising a second threaded disk recessed within the interior channel, and wherein the first threaded disk and the second threaded disk are abutted to adjust strain of the elongate body.

9. The resonance frequency vibration power harvester of claim 1 and further comprising a second vibration energy harvester device attached adjacent the first end of the elongate body.

10. The resonance frequency vibration power harvester of claim 9 wherein the first vibration energy harvester device is aligned along the elongate body for harvesting energy in a first direction and the second vibration energy harvester device is aligned along the elongate body for harvesting energy in a second direction.

11. The resonance frequency vibration power harvester of claim 9 wherein the first vibration energy harvester device and the second vibration energy harvester device are aligned to harvest energy in one direction of vibration of the elongate body.

12. The resonance frequency vibration power harvester of claim 1 and further comprising an opening in the elongate body adjacent the first vibration energy harvester device.

13. The resonance frequency vibration power harvester of claim 12 wherein the first vibration energy harvester device is cantilevered over the opening and includes a weight positioned at a free end of the first vibration energy harvester device.

14. The resonance frequency vibration power harvester of claim 13 and further comprising mechanical stops to limit the movement of the cantilevered vibration energy harvester device.

15. The resonance frequency vibration power harvester of claim 1 wherein the density of the elongate body varies from the first end to the second end.

16. The resonance frequency vibration power harvester of claim 1 wherein the first vibration energy harvester device comprises an electromagnetic or a piezoelectric generator.

17. The resonance frequency vibration power harvester of claim 1 and further comprising an opening in the elongate body for receiving circuitry while allowing the weight to traverse the elongate body.

18. The resonance frequency vibration power harvester of claim 17 wherein:

the resonance frequency vibration power harvester further includes;

harvester circuitry positioned within the opening; and

a first cable for connecting the first vibration energy harvester device with the harvester circuitry; and

the vibration source comprises an industrial process control system including a conduit and a process transmitter, wherein the process transmitter comprises;

a sensor for sensing a parameter of a process fluid in the conduit and for generating a sensor signal that is a function of the sensed parameter;

transmitter electronics connected to the sensor, wherein the transmitter electronics condition the sensor signal to produce a transmitter output representative of the sensed parameter; and

a power cable connecting the harvester circuitry to the transmitter electronics.

19. An adjustable frequency vibration power harvester comprising:

a base for connecting to a vibration source;

a beam comprising;

a first end for connection with the base;

a second end having an opening;

an elongate hollow midspan portion extending between the base and the opening;

a first vibration energy harvester device attached nearer the first end than the second end; and

a first mass adjustably positioned in the elongate hollow midspan portion to adjust vibration properties of the beam.

20. The adjustable frequency vibration power harvester of claim 19 wherein the mass comprises an elongate threaded cylinder for traversing threaded engagements in the hollow midspan portion.

21. The adjustable frequency vibration power harvester of claim 20 wherein the elongate threaded cylinder extends from the hollow midspan portion to increase overall length of the beam.

22. The adjustable frequency vibration power harvester of claim 19 wherein the mass comprises a first threaded disk for traversing threaded engagements in the hollow midspan portion.

23. The adjustable frequency vibration power harvester of claim 22 wherein the threaded disk is recessed within the hollow midspan portion to adjust midspan mass of the beam.

24. The adjustable frequency vibration power harvester of claim 22 and further comprising a second threaded disk recessed within the hollow midspan portion, and wherein the first threaded disk and the second threaded disk are abutted to adjust strain of the beam.

25. The adjustable frequency vibration power harvester of claim 19 and further comprising a second vibration energy harvester device attached nearer the first end than the second end of the beam, and wherein the first vibration energy harvester device is aligned along the beam for harvesting energy in a first direction and the second vibration energy harvester device is aligned along the beam for harvesting energy in a second direction.

26. The adjustable frequency vibration power harvester of claim 19 wherein the first vibration energy harvester device is cantilevered over an opening along the hollow midspan portion and includes a weight positioned at a free end of the first vibration energy harvester device.

27. The adjustable frequency vibration power harvester of claim 19 wherein the density of the beam varies from the first end to the second end.

28. The adjustable frequency vibration power harvester of claim 19 wherein the first vibration energy harvester device comprises an electromagnetic or a piezorelectric generator.

29. A method for adjusting frequency of a vibration power harvesting device, the method comprising:

mounting a vibration power harvester device adjacent a first end of a beam;

mounting a second end of the beam to a vibration source such that the vibration power harvester is cantilevered from the vibration source;

adjusting a position of a first mass within the beam until the beam vibrates at resonance.

30. The method for adjusting frequency of a vibration power harvesting device of claim 29 wherein the step of adjusting the position of the first mass within the beam comprises extending the first mass partially beyond the first end of the beam.

31. The method for adjusting frequency of a vibration power harvesting device of claim 29 wherein the step of adjusting the position of the first mass within the beam comprises recessing the first mass completely within the beam.

32. The method for adjusting frequency of a vibration power harvesting device of claim 31 and further comprising the step of adjusting position of a second mass within the beam such that it abuts the first mass to cause a change in strain of the beam.