FLUIDIC ELECTROSTATIC ENERGY HARVESTER

• US 20090080138A1
• Filed: 09/20/2007
• Published: 03/26/2009
• Est. Priority Date: 09/20/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Theuss, Horst, Kvisteroey, Terje, Blixhavn, Bjoern, Lohndorf, Markus
• Granted Patent: US 7,872,851 B2
• Time in Patent Office: Days
• US Class Current: 361/292
• CPC Class Codes: B60C 23/041 Means for supplying power to the signal- transmitting means on the wheel
• CPC Class Codes: H01G 5/0132 Liquid dielectrics
• CPC Class Codes: H01G 5/04 using variation of effective area of electrode
• CPC Class Codes: H01G 5/40 Structural combinations of variable capacitors with other electric elements not covered by this subclass, the structure mainly consisting of a capacitor, e.g. RC combinations

Abstract

One embodiment of the present invention relates to a variable capacitor that operates without moving mechanical parts. In this capacitor electrically conductive electrodes are separated by an enclosed chamber filled with an electrically conductive material. The electrically conductive material can freely vary its position within the chamber. The capacitance of the device will vary as position of the conductive material changes due to external mechanical motion (ex: rotation vibration, etc.) of the device. Other embodiments of this device are also disclosed.

Claims

1. A variable capacitor, comprising:

two electrically conductive electrodes;

an enclosed chamber disposed between the electrically conductive electrodes;

an electrically conductive material disposed in the chamber and configured to change position within the chamber upon motion or change in orientation of the variable capacitor; and

an insulating layer disposed between the conductive electrodes.

2. The variable capacitor of claim 1, further comprising an electret material layer disposed between the two conductive electrodes.

3. The variable capacitor of claim 2, wherein the insulating layer comprises the electret material layer.

4. The enclosed chamber of claim 1, wherein the electrically conductive material comprises an electrically conductive fluid.

5. The variable capacitor of claim 4, wherein the fluid comprises one or more of a fluid metal, an ionic solution, and a fluid highly doped with metallic particles.

6. The variable capacitor of claim 1, further comprising one or more electrically conductive posts electrically coupled to and normal to one of the electrodes.

7. The variable capacitor of claim 1, further comprising electrically conductive inside walls formed about at least a part of a sidewall portion of the enclosed chamber.

8. The variable capacitor of claim 7, further comprising one or more electrically conductive posts electrically coupled to and normal to one of the electrodes.

9. The variable capacitor of claim 8, wherein the conductive post and the conductive inside walls comprise the same conductive material.

10. A tire sensor system, comprising:

a variable capacitor comprising two electrically conductive electrodes, wherein at least one electrode is adapted to change size as the capacitor undergoes physical motion, thereby resulting in a change of capacitance;

an energy storage circuit configured to utilize the change in capacitance to store electrical energy;

a tire sensor module configured to use the stored electrical energy; and

a mount apparatus configured to mount the variable capacitor and sensor module onto a tire such that the variable capacitor will undergo physical motion as the tire moves.

11. The tire sensor system of claim 10, further comprising a battery coupled to the energy storage circuit and the tire sensor module.

12. The tire sensor system of claim 11, further comprising a transmitter or transceiver, coupled to the battery and the tire sensor module, configured to wirelessly transmit data.

13. The tire sensor system of claim 12, further comprising a central processing unit configured to receive the data from the transmitter or transceiver.

14. A method for converting mechanical energy to electrical energy, comprising:

placing charges on two electrodes of a variable capacitor;

generating an electrical energy through changing the location of the charges on the electrodes by changing the size of at least one electrode; and

storing the generated electrical energy.

15. The method of claim 15, wherein the size of the electrodes is changed by rotating the variable capacitor or vibrating the variable capacitor.

16. The method of claim 15, wherein the charges are placed on the electrodes of the variable capacitor by connecting the electrodes to a voltage source.

17. The method of claim 15, wherein the charges are placed on the electrodes of the variable capacitor by including an electret material between the electrodes.

18. The method of claim 15, wherein the resultant energy is stored in a local charge store.

19. An energy harvesting system, comprising:

means for placing charges initially on the electrodes of a variable capacitor;

means for changing a size of the electrodes of a variable capacitor through an external motion of the variable capacitor thereby resulting in a change in capacitance; and

means for converting the change in capacitance to stored electrical energy.

20. The system of claim 21, further comprising means for storing energy associated with a change in capacitance of the variable capacitor.