Energy conversion system with variable airgap distance and energy recovery method

Abstract

The main purpose of this invention is a system for conversion of mechanical energy into electrical energy by electrostatic conversion, comprising at least one fixed electrode (2) and at least one mobile electrode (4) that can be vibrated by mechanical energy, facing the fixed electrode, said fixed (2) and mobile (4) electrodes being separated at rest by an air gap distance (Δ), said system comprising means (12) of modifying the air gap distance as a function of the variation of the vibration amplitude of the mobile electrode (4).

Description

BRIEF DESCRIPTION OF THE FIGURES

This invention will be better understood after reading the following description and appended figures, wherein:

FIG. 1 shows a block diagram of a system according to this invention at rest,

FIG. 2A is an example embodiment of a first method of making an energy conversion system according to this invention in a first configuration of the adjustment of the air gap distance,

FIG. 2B is a diagrammatic representation of a second configuration of the adjustment of the air gap distance of the system in FIG. 2A,

FIG. 3A is a diagrammatic representation of a second example embodiment for a conversion system according to this invention in a first configuration of adjustment of the air gap distance,

FIG. 3B is a diagrammatic representation of the system in FIG. 3A, in a second configuration of the adjustment of the air gap distance,

FIG. 4 is a diagrammatic representation of a second embodiment of a conversion system according to this invention,

FIG. 5 contains a flowchart showing operation of the system in FIG. 4,

FIGS. 6A and 6B are graphic representations of the change in the capacitance variation of a conversion system according to the state of the art.

Claims

1. System for conversion of mechanical energy into electrical energy by electrostatic conversion, comprising at least one fixed electrode and at least one mobile electrode that can be vibrated by mechanical energy, said fixed and mobile electrodes being separated at rest by an air gap distance, said system comprising at leaést an adjuster of modifying the air gap distance as a function of the variation of the vibration amplitude of the mobile electrode.

2. System set forth in claim 1, wherein the adjuster enables adjustment before an energy conversion step.

3. System set forth in claim 2, wherein the adjuster is composed of a set of calibrated spacers that can be placed between the fixed electrode and the mobile electrode, one or several spacers being used.

4. System set forth in claim 2, wherein the passive adjuster is inserted between the fixed electrode and the mobile electrode, and can be controlled to modify the air gap distance.

5. System set forth in claim 4, wherein the adjuster is of the rack and pinion or slide and worm screw type.

6. System set forth in claim 1, wherein the adjuster enables modification of the air gap distance (Δ) during an energy conversion step.

7. System set forth in claim 6, wherein the adjuster comprises an actuator inserted between the fixed electrode and the mobile electrode and a control of said actuator.

8. System set forth in claim 7, wherein the actuator may be a motor, a cylinder, piezoelectric and/or magnetostrictive elements.

9. System set forth in claim 7, wherein the control is independent and automatically activates the actuator to adapt the air gap distance to the variation of the vibration amplitude.

10. System set forth in claim 9, wherein the adjuster comprises sensors detecting the variation in the vibration amplitude, and wherein the control comprises an electronic unit comprising correspondence maps between values of the air gap distance and displacement amplitude intervals of the mobile part enabling optimum energy recovery.

11. System set forth in claim 10, wherein the sensors are of the accelerometer type or of the variation amplitude detection stop type.

12. System set forth in claim 9, wherein the adjuster also comprises a manual control.

13. System set forth in claim 1, comprising several mobile electrodes in the form of fingers, and wherein the fixed electrode comprises fingers, the fingers of the fixed electrode and the mobile fingers being interdigitized.

14. System set forth in the above claim, wherein the mobile fingers move along the direction of their largest dimension.

15. System set forth in claim 13, wherein the fingers move perpendicular to their largest dimension.

16. System set forth in claim 13, wherein the fingers are trapezoidal in shape.

17. Method of conversion of mechanical energy into electrical energy using a conversion system comprising at least one fixed electrode and one mobile electrode facing it, and an adjuster able to modify the air gap distance between the fixed electrode and the mobile electrode comprising a step to: adjust the air gap distance before the energy conversion phase, as a function of the variation in the amplitude of vibrations of the mobile electrode.

18. Energy conversion method set forth in the above claim, comprising the following steps: to determine the maximum expected displacement amplitude of the mobile part,to choose a maximum air gap distance, these steps taking place before the step to adjust the air gap distance.

19. Method of conversion of mechanical energy into electrical energy making use of a conversion system comprising at least one fixed electrode and one mobile electrode facing it, and an adjuster able to modify the air gap distance between the fixed electrode and the mobile electrode, comprising a step to: adjust the air gap distance during the energy conversion phase, as a function of the variation of the vibration amplitude of the mobile electrode.

20. Energy conversion method set forth in the above claim, comprising the following steps during the energy conversion phase: measure the displacement amplitude of the mobile part during the conversion phase,choose between air gap distance values and amplitude intervals from a correspondence map to achieve optimum energy recovery, these steps taking place before the step to adjust the air gap distance.

21. Method of manufacturing a system set forth in claim 1, by electroerosion and laser cutting.

22. Method of manufacturing a system set forth in claim 1, wherein the actuator is integrated on silicon.

23. Manufacturing method set forth in the above claim, wherein the actuator is composed of piezoelectric elements deposited by cathode sputtering.