WO2018020639A1

WO2018020639A1 - Power generation device and power generation element

Info

Publication number: WO2018020639A1
Application number: PCT/JP2016/072148
Authority: WO
Inventors: 岡田　和廣; 聡江良
Original assignee: 株式会社トライフォース・マネジメント
Priority date: 2016-07-28
Filing date: 2016-07-28
Publication date: 2018-02-01
Also published as: JPWO2018020639A1; JP6309698B1

Abstract

Provided are a power generation device and a power generation element that are able to efficiently convert mechanical vibration energy that includes various directional components into electrical energy, are able to achieve high power generation efficiency, have a simple structure and high strength, and can easily be made smaller. The power generation element is equipped with: flexible bridge parts 26 having a longitudinal shaft; a support frame part 24 to which the base-end part 26b of the bridge parts 26 are secured; weight bodies 32, which continue from the tip-end part 26a of the longitudinal shaft of the bridge parts 26, and are provided bending toward the base-end part 26b of the bridge parts 26, with a prescribed interval therebetween; and a piezoelectric elements 34 at a prescribed position on the surface of the bridge parts 26 at which expansion/contraction deformation occurs. The piezoelectric elements 34 are equipped with a plurality of electrodes E0, E1, E2, E3, and E4. A plurality of the power generation elements 21, 22, and 23 are secured in the middle of the support frame part 24. The Eigen frequency of the vibration system of each power generation element 21, 22, and 23 is a different frequency.

Description

Power generator and generator element

The present invention relates to a power generation device that converts mechanical vibrational energy into electrical energy by using a piezoelectric effect, and a power generation element used therefor.

In recent years, various power generation elements that convert mechanical vibrational energy into electrical energy using the piezoelectric effect have been proposed as means for obtaining electrical energy. A general power generation element of this type supports a weight body by a cantilever whose one end is fixed, and causes vertical deflection of the beam portion by vertical vibration of the weight body, and the force due to this bending is used as a piezoelectric element To generate charge. In such a system, power generation efficiency is low because only vibration energy in one direction that vibrates the weight body in the vertical direction can be used.

Also, in a piezoelectric power generation element using MEMS (Micro Electro Mechanical System) technology, the piezoelectric element is disposed on a silicon substrate, the force acting on the weight body is transmitted to the piezoelectric element, and the mechanical force is piezoelectric effect To generate electric charge. This power generation element is designed in accordance with the resonance frequency of the installed environment in order to enhance the power generation efficiency. Furthermore, since the vibrating body is made of Si (silicon) or metal, the peak (Q value) of the resonant frequency is high but the half width is narrow, so the resonant frequency of the power generation element is the frequency of the vibration of the environment used. You need to adjust to

Therefore, in order to increase the power generation efficiency of the power generation element, the power generation element disclosed in Patent Document 1 is a bridge portion of a cantilever structure in which a weight body is disposed asymmetrically bent around the weight body. A piezoelectric body is fixed to a bridge portion supported and bent and arranged, and an electrode is arranged on the piezoelectric body. As a result, mechanical vibrational energy in a plurality of directions orthogonal to each other can be used for power generation, and power generation efficiency is increased.

In addition, in the power generation element disclosed in Patent Document 2, at least a plurality of resonators different in resonance frequency (natural frequency) are arranged in a cantilever shape, and a piezoelectric member and an electrode are provided on the resonator. Thereby, mechanical vibrations of a plurality of different frequencies are propagated from the resonator to the piezoelectric element, and mechanical vibrations in a wide frequency band are converted into electrical energy.

Patent No. 5529328 gazette JP, 2010-273408, A

In general, mechanical vibration of various frequencies is mixed in an environment in which a power generation element is used, and is not limited to a specific frequency or a specific vibration direction. Further, there is a problem that the resonance frequency (natural frequency) of the structure made of Si or metal also changes due to external stress or temperature fluctuation. Therefore, even if the resonant frequency of the power generation element is adjusted to the frequency of the vibration of the usage environment, there is a problem that the power generation efficiency is lowered due to temperature fluctuation or the like, or the power generation does not occur.

Furthermore, in the case of the structure of the power generation element disclosed in Patent Document 1, there is a need to make the bridge portion as long and thin as possible in order to generate a sufficient hand in the bridge portion and to improve power generation efficiency. However, if the bridge portion is long and thin, the structure is enlarged and mechanical strength is reduced, and the bridge portion may be damaged if excessive vibration is applied during use, and the piezoelectric element is formed. There were also restrictions on the arrangement of the electrodes and weights.

In the power generation element disclosed in Patent Document 2, the direction of vibration is limited to one axial direction, and vibrations in various directions in the use environment can not be efficiently converted into electrical energy.

The present invention has been made in view of the above background art, and can efficiently convert mechanical vibrational energy including various directional components into electrical energy to obtain high power generation efficiency, and the structure is simple. It is an object of the present invention to provide a power generating device and a power generating element which are high in strength and easy to be miniaturized.

The present invention is a power generation device including a power generation element that generates power by converting mechanical vibration energy into electrical energy, wherein the power generation element has a longitudinal axis and has a flexible bridge portion The support frame portion to which the base end portion of the bridge portion is fixed and the tip end portion of the longitudinal axis of the bridge portion are continuous, and bent toward the base end portion of the bridge portion at a predetermined distance A weight body provided, a piezoelectric element fixed at a predetermined position where expansion and contraction of the surface of the bridge portion is generated, and a plurality of electrodes fixed to the piezoelectric element and outputting charges generated in the piezoelectric element The plurality of power generation elements are fixed in the support frame portion, the natural frequency of the vibration system of each power generation element is configured with different frequencies, and each electrode of each power generation element is generated in the piezoelectric element Take out the charge and output the power A power generator connected to the electric circuit.

The center of gravity of the weight body is located within an projection range of the bridge portion and on an axis parallel to the longitudinal axis at a predetermined distance. Furthermore, it is preferable that the weight body is bent in a symmetrical shape on both sides of the bridge portion.

The vibration system of each of the power generation elements is set to a different natural frequency due to the difference in mass of the weight body. Alternatively, the vibration system of each of the power generation elements may be set to a different natural frequency due to the difference in the elastic coefficient or the shape of the bridge portion.

The vibration systems of the power generation elements may be physically connected to each other so that one vibration can be transmitted to the other. In each of the vibration systems, weights are connected to each other by a connector.

Further, the present invention is a power generation element that generates electric power by converting mechanical vibration energy into electric energy, wherein the bridge portion having a longitudinal axis and having flexibility, and the base end portion of the bridge portion A fixed supporting frame portion, a weight body which is continuous with the tip end portion of the longitudinal axis of the bridge portion and which is provided at a predetermined interval and bent toward the base end portion of the bridge portion; And a plurality of electrodes fixed to the piezoelectric element and outputting charges generated in the piezoelectric element, wherein the center of gravity of the weight body is: It is an electric power generation element which is located within an projection range of the bridge portion and on an axis parallel to the longitudinal axis at a predetermined interval.

The weight body is fixed to a weight body supporting portion positioned in parallel with the bridge portion at a predetermined interval, and a gravity center position of the weight body is positioned at a predetermined distance from a center of the bridge portion. It is

The bridge portion and the weight body support portion are formed of the same plate material, a piezoelectric material layer is stacked on one surface of the bridge portion and the weight body support portion, and the weight body is formed on the other surface. A projected shape of the layer formed of the bridge portion and the weight body support portion, the piezoelectric material layer, and the weight body in the stacking direction is the same.

According to the power generation device of the present invention, in the environment where the power generation device is provided, the vibration system of each power generation element resonates at different frequencies with respect to vibration in a wide frequency band, and mechanical vibration of the external world is efficiently performed. It can be converted into electrical energy and taken out.

Furthermore, according to the power generation element of the present invention, the direction of external mechanical vibration can also be stably oscillated by picking up vibration in all directions of the XYZ Cartesian coordinate system, so that it can be changed to electrical energy, which is more efficient. Power generation can be performed. In addition, the power generation device and the power generation element of the present invention are simple in structure, high in strength, and easily reduced in size.

It is a schematic plan view which shows 1st embodiment of the electric power generating apparatus of this invention. It is a block diagram showing a vibration system and a power generation circuit of a first embodiment. It is a disassembled perspective view of the unit power generation element used for the electric power generating apparatus of 1st embodiment. It is a top view of the unit power generation element of a first embodiment. FIG. 5 is a cross-sectional view taken along line AA of FIG. 4; It is a figure which shows the electric power generation circuit of 1st embodiment. A plan view showing a state in which a force Fx in the X-axis direction is applied to the unitary power generation element of the first embodiment (a), a plan view showing a state in which a force Fy in the Y-axis direction is applied, (b) It is a top view (c) which shows the state where force Fz was added. Graph (a) showing the frequency characteristic of vibration in the X axis direction of the power generation zone of each unit power generation element of the power generation device of the first embodiment (a) Graph showing frequency characteristic of vibration in the Y axis direction (b) It is a graph (c) which shows the frequency characteristic of vibration. It is a top view which shows the electric power generating apparatus of 2nd embodiment of this invention. It is a top view which shows the electric power generating apparatus of 3rd embodiment of this invention. It is a top view which shows two basic vibration systems for demonstrating the electric power generating apparatus of 3rd embodiment. It is a graph (a) which shows the frequency characteristic of only one fundamental vibration system for demonstrating the electric power generating apparatus of 3rd embodiment, and the graph (b) which shows the frequency characteristic of only the other fundamental vibration system. It is the schematic which shows two basic vibration systems and the electric power generation circuit for demonstrating the electric power generating apparatus of 3rd embodiment. It is a graph (a) which shows the frequency characteristic of one basic vibration system which provided the connection body of the electric power generating apparatus of 3rd embodiment, and a graph (b) which shows the frequency characteristic of the other basic vibration system. They are a side view (a) and a top view (b) which show the unit power generation element of the electric power generating apparatus of 4th embodiment of this invention.

Hereinafter, a first embodiment of a power generation apparatus according to the present invention will be described based on FIGS. 1 to 8. The power generation apparatus 10 of this embodiment is provided with a plurality of

vibration systems

11, 12 and 13 having different natural frequencies (resonance frequencies), and each of the

vibration systems

11, 12 and 13 includes unit

power generation elements

21 and 22 respectively. , 23, and the outputs of the unit

power generation elements

21, 22, 23 are connected to the power generation circuit 14. Each

vibration system

11, 12, 13 has the same configuration, and has different natural frequencies depending on the length and mass of each part. First, based on the unitary power generation element 21 of the vibration system 11, the basic structure of the unitary power generation element 21 of this embodiment will be described below. Here, the directions in the present invention will be described based on a three-dimensional orthogonal coordinate system in the XYZ axis directions orthogonal to each other, and the XY plane will be described as the horizontal plane, and the Z axis direction is the vertical direction and the vertical direction.

The unit power generation element 21 is provided with a bridge portion 26 integrally provided projecting in the Y-axis direction from the inner wall surface 24 a of the rectangular frame-shaped hollow support portion 24 of the power generation device 10. The bridge portion 26 has a constant thickness in the Z-axis direction, and is formed in an elongated rectangular shape having a longitudinal axis in the Y-axis direction.

At the distal end portion 26a of the bridge portion 26, an L-shaped weight support portion 28 extends from the distal end portion 26a by a predetermined distance in the X-axis direction and further toward the proximal end portion 26b of the bridge portion 26 in the Y-axis direction. They are provided symmetrically about the longitudinal axis in the Y-axis direction with the bridge portion 26 interposed therebetween. Each weight support portion 28 is integrally formed with the support portion 24 from the same plate material as the bridge portion 26. The bridge portion 26 and the pair of weight support portions 28 are substantially E-shaped on the XY plane. It is provided. Therefore, the bridge portion 26 and the portion parallel to the Y axis of the weight support portion 28 extend at a constant spacing s. The length of the weight support portion 28 in the Y-axis direction is shorter than that of the bridge portion 26, and the end 28a of the weight support portion 28 is located away from the inner wall surface 24a of the support portion 24. .

The material of the support portion 24, the bridge portion 26 and the weight body support portion 28 is not limited, and in view of the manufacturing method and the like described later, it is preferable to be formed of silicon, ceramics or the like. As described later, the materials of the bridge portion 26 and the weight body support portion 28 may be formed to have either insulating or conductive properties with respect to the lower layer electrode E0.

A piezoelectric material layer 30 formed of a piezoelectric material such as lead-free piezoelectric ceramics such as lead zirconate titanate (PZT) or sodium potassium niobate, or piezoelectric resin is provided on the upper layer in the Z-axis direction of the bridge portion 26 It is done. The piezoelectric material layer 30 is formed in a layer shape, and is formed in an E shape having the same shape as the bridge portion 26 and the weight body support portion 28 in the Z-axis direction. The lower layer electrode E0 is integrally formed in the same shape between the bridge portion 26 and the weight body support portion 28 and the piezoelectric material layer 30, and the bridge portion 26 and the weight body support portion 28 are formed via the lower layer electrode E0. It is provided integrally with the piezoelectric material layer 30.

The piezoelectric material layer 30 in the portion laminated on the bridge portion 26 is a portion functioning as the piezoelectric element 34, and on the surface side of the piezoelectric element 34 on the opposite side to the lower layer electrode E0, four upper layer electrodes E1, E2,. E3 and E4 are provided. The upper layer electrodes E1, E2, E3 and E4 are stacked at four locations at both ends of the piezoelectric element 34 in the X-axis direction and at both ends in the Y-axis direction, and are connected to the power generation circuit 14 together with the lower layer electrode E0. While the lower layer electrode E0 is a common electrode formed on the entire lower surface of the piezoelectric element 34, each upper layer electrode E1 to E4 is a piezoelectric effect which is a region where the piezoelectric effect of the piezoelectric element 34 occurs. It is provided as an electrode formed on the part. As described later, the directions (the compression direction and the extension direction) of the stress applied to each portion of the piezoelectric element 34 differ depending on the direction of the external force acting on the unit power generation element 21 and occur in each piezoelectric effect portion of the piezoelectric element 34. This is because the positive or negative charges generated in each of the upper layer electrodes E1 to E4 can be efficiently taken in due to the difference in polarity of the electric field.

The piezoelectric material layer 30 may not be laminated because almost no bending occurs in the weight body support portion 28 due to an external force and no stress is generated. Furthermore, the piezoelectric element 34 formed of the piezoelectric material layer 30 may be stacked on the entire surface of the bridge portion 26, or may be only the region where the upper layer electrodes E1, E2, E3 and E4 are disposed. However, in this embodiment, it is laminated in the same shape as the bridge portion 26 and the weight body support portion 28 for reasons of manufacturing and the like described later.

A weight body 32 is integrally attached to the lower layer in the Z-axis direction of the weight body support portion 28. The weight 32 is integrally attached to a pair of L-shaped weight support portions 28 and has the same shape as the projection shape in the Z-axis direction in which the pair of L-shaped weight body support portions 28 are symmetrically opposed. In, it is formed in the gate shape. The weight body 32 has a constant thickness in the Z-axis direction, has a large mass in a portion parallel to the bridge portion 26, and is formed to a predetermined mass. The length of the weight body 32 in the Y-axis direction is shorter than that of the bridge portion 26, and the end 32 a of the weight body 32 is at the same position as the end 28 a of the weight body support 28. It is located slightly away from the inner wall surface 24a. Thereby, in the power generation operation described later, even when the weight body 32 swings, the end 32 a of the weight body 32 does not collide with the inner wall surface 24 a of the support portion 24.

The weight body 32 is formed in a gate shape along the weight body support portion 28, so a space 35 is formed in the lower portion of the bridge portion 26 in the Z-axis direction. The gravity center position G of the weight body 32 is the center of the bridge portion 26 in the X-axis direction as shown in FIG. 4 and FIG. 5 and is spaced downward from the bridge portion 26 downward in the Z-axis direction. is there. The gravity center position G of the weight body 32 in the Y-axis direction of the bridge portion 26 is within the projection range of the bridge portion 26 and is slightly closer to the tip portion 26 a than the central portion.

It is preferable to use a material having a specific gravity as large as possible for the weight body 32. For example, a metal such as SUS, iron, copper, tungsten, or a ceramic or glass may be used. Furthermore, as described later, in the case where the unitary

power generation elements

21, 22, 23 are made using MEMS technology, the weight body 32 may be made of Si.

Next, the power generation device 10 provided with the unit

power generation elements

21, 22, 23 according to this embodiment will be described. As shown in FIG. 1, the power generation device 10 is provided with unit

power generation elements

22 and 23 having the same configuration as that of the above-described unit power generation element 21 in the support portion 24. The support portion 24 is formed in a hollow rectangular frame shape, and on the XY plane inside the support portion 24, the unitary

power generation elements

21, 22, 23 extend in the Y-axis direction and are respectively positioned. The

vibration systems

11, 12, 13 constituting the unitary

power generation elements

21, 22, 23 have different natural frequencies and resonate at different frequencies. In this embodiment, the weight bodies 32 of the unitary

power generation elements

21, 22, 23 have different sizes and different masses so that they have different natural frequencies.

In order to make each

vibration system

11, 12, 13 have different natural frequencies, the width or length may be changed so that the elastic modulus of the bridge portion 26 is different, even if the thickness, the laminated material, or the shape is changed. good. Furthermore, both the masses of the

vibration systems

11, 12, 13 and the elastic coefficients of the bridge portions 32 may be set to different values.

Next, the power generation circuit 14 of this embodiment will be described based on FIG. Here, although it demonstrates based on the example connected to the unit power generation element 21, the other unit

power generation elements

22 and 23 are also connected to the same power generation circuit 14 by the same circuit structure. Of the piezoelectric element 34 stacked on the bridge portion 26, portions facing the upper layer electrodes E1, E2, E3 and E4 and the periphery thereof are portions where the piezoelectric effect is efficiently generated. The upper layer electrodes E1, E2, E3 and E4 The parts facing each other are referred to as piezoelectric effect parts P1, P2, P3 and P4.

The upper layer electrode E1 attached to the piezoelectric effect portion P1 is connected to the anode of the diode D11 forming the rectification circuit of the power generation circuit 14 and the cathode of the diode D12 respectively, and the cathode of the diode D11 stores charges in the power generation circuit 14 One end of the capacitor Cf is connected, and the anode of the diode D12 is connected to the other end of the capacitor Cf.

Similarly, the upper layer electrode E2 attached to the piezoelectric effect portion P2 is connected to the anode of the diode D21 forming the rectification circuit of the power generation circuit 14 and the cathode of the diode D22, and the cathode of the diode D21 is a capacitor One end of Cf is connected, and the anode of the diode D22 is connected to the other end of the capacitor Cf.

Similarly, the upper layer electrode E3 attached to the piezoelectric effect portion P3 is connected to the anode of the diode D31 forming the rectification circuit of the power generation circuit 14 and the cathode of the diode D32, and the cathode of the diode D31 is a capacitor One end of Cf is connected, and the anode of the diode D32 is connected to the other end of the capacitor Cf.

Similarly, the upper layer electrode E4 attached to the piezoelectric effect portion P4 is connected to the anode of the diode D41 forming the rectification circuit of the power generation circuit 14 and the cathode of the diode D42, and the cathode of the diode D41 stores a charge. One end of Cf is connected, and the anode of diode D42 is connected to the other end of capacitor Cf.

Furthermore, the lower layer electrode E0 is connected to the anode of the diode D01 and the cathode of the diode D02, and the cathode of the diode D01 is connected to one end of the capacitor Cf storing electric charge, and the anode of the diode D02 is connected to the other end of the capacitor Cf. It is connected.

Thereby, even if positive or negative charges are generated in the upper layer electrodes E1, E2, E3 and E4 by the respective piezoelectric effect portions P1, P2, P3 and P4, they can be accumulated in the capacitor Cf with the same polarity. Furthermore, in this embodiment, the lower layer electrodes E0 and the upper layer electrodes E1, E2, E3, E4 of the three unit

power generation elements

21, 22, 23 are similarly connected to the diodes D11 to D42 and connected to the capacitor Cf. Thereby, the charge generated by the three unit

power generation elements

21, 22, 23 can be stored in the capacitor Cf. The capacitor Cf is connected to various loads ZL in use.

The power generation device 10 of this embodiment is suitable for a power supply of a sensor manufactured by MEMS technology and the like, and a minute structure is required. Therefore, each bridge portion of the support portion 24 and the unit

power generation elements

21, 22, 23 The materials of the weight support portion 28 and the weight support portion 28 can be manufactured using Si and utilizing the process of forming a semiconductor circuit. In this case, for example, the thickness in the Z-axis direction of the bridge portion 26 and the weight support portion 28 is about 200 μm, the same thickness of the piezoelectric layer 30 is 2 μm, and the thickness of the weight 32 in the Z-axis direction The thickness is set to about 1000 μm, and the thicknesses of the lower layer electrode E0 and the upper layer electrodes E1 to E4 are set to about 0.01 μm, and the outer shape can be manufactured in a size of about 5 mm × 5 mm. In the manufacturing process, the lamination process such as etching and vapor deposition is repeated in the Z-axis direction. Other processes such as printing and sputtering can also be used. In this case, an SOI substrate is preferably used as the Si substrate. The lower layer electrode E0, the piezoelectric body 34, and the upper layer electrodes E1 to E4 may be formed on the active layer Si of the SOI substrate, and the base Si may be a weight body 32.

In addition, it is also possible to use a metal plate for each bridge portion 26 of the support portion 24 and the unit

power generation elements

21, 22, 23. In that case, it is preferable to form the metal plate in a predetermined shape by etching or the like, the upper surface of the metal plate to function as the lower electrode E0, and deposit a thin film of a piezoelectric material on the metal plate by the Sbutter method or Solgenol method. Further, the upper layer electrode can be formed of a metal material by printing, vapor deposition, sputtering, or the like.

Next, the power generation operation of the unit power generation element 21 of this embodiment will be described. Here, the support portion 24 is placed on the XY plane, and the hollow portion penetrates in the Z-axis direction. First, the case where an acceleration acts on the weight body 32 of the unit power generation element 21 shown in FIGS. 3 to 5 due to vibration or the like and a force is applied will be described.

First, the case where the force + Fx in the positive direction of the X axis acts will be described. As the center of gravity G of the weight body 32 is located at the substantially central part of the bridge portion 26 downward in the Z-axis direction, when an external force + Fx acts, the piezoelectric element 34 of the bridge portion 26 is shown in FIG. In the following, the force acts. A force in the compression direction acts on the piezoelectric effect portion P1 opposed to the upper layer electrode E1, and a force in the extension direction acts on the piezoelectric effect portion P2 opposed to the upper layer electrode E2, and a piezoelectric effect opposed to the upper layer electrode E3. A force in the extension direction acts on the portion P3, and a force in the compression direction acts on the piezoelectric effect portion P4 opposed to the upper layer electrode E4. As a result, electric fields of opposite polarities are generated in the piezoelectric effect portions P1 and P2, and electric fields of opposite polarity are also generated in the piezoelectric effect portions P3 and P4, and the electric fields of the piezoelectric effects portions P1 and P3 become opposite polarities. Occur. Then, charges of the same polarity are generated in the upper layer electrodes E1 and E4, and charges of the same polarity and reverse polarity to the upper layer electrodes E1 and E4 are generated in the upper layer electrodes E2 and E3, respectively. The charges accumulated in each of the electrodes E0 to E4 are reverse in polarity between the upper layer electrodes E1 and E4 and the upper layer electrodes E2 and E3, but are rectified by the circuit shown in FIG. Be stored. Similarly, when a negative force -Fx acts in the negative direction of the X-axis, charges are generated in each electrode with the opposite polarity to the above, but the circuit shown in FIG. Is stored.

Next, the case where a force + Fy in the Y-axis positive direction acts on the weight body 32 of the unitary power generation element 21 will be described. The center of gravity G of the weight body 32 is located below the substantially central portion of the bridge portion 26 in the Z-axis direction, so when a force + Fy in the positive Y-axis direction is applied, the bridge portion 26 is watched in FIG. A moment in the direction acts. As a result, as shown in FIG. 7B, the force in the compression direction acts on the piezoelectric effect portions P1, P2, P3 and P4 facing the respective upper layer electrodes E1, E2, E3 and E4, respectively. Each generates an electric field of the same polarity. As a result, charges are generated in the respective upper layer electrodes E1, E2, E3 and E4 with the same polarity, rectified by the circuit shown in FIG. 6, and the charges are accumulated in the capacitor Cf. Similarly, when a negative force -Fy acts in the Y-axis negative direction, charges are generated with the opposite polarity to the above, but charges are accumulated in the capacitor Cf with the same polarity by the circuit shown in FIG.

Next, the case where a force + Fz in the positive direction of the Z-axis acts on the weight body 32 of the unitary power generation element 21 will be described. The center of gravity G of the weight body 32 is located below the substantially central portion of the bridge portion 26 in the Z-axis direction. Therefore, as shown in FIG. 7C, piezoelectric effect portions facing the respective upper layer electrodes E1 and E2 A force in the extension direction acts on P1 and P2 to generate electric fields of the same polarity, and charges are generated on the respective upper layer electrodes E1 and E2 with the same polarity. On the other hand, a force in the compression direction acts on the piezoelectric effect portions P3 and P4 facing the respective upper layer electrodes E3 and E4, and an electric field having a polarity opposite to that of the piezoelectric effect portions P1 and P2 is generated. On the other hand, charges of the opposite polarity to the upper layer electrodes E1 and E2 are generated, but the charges are rectified by the circuit shown in FIG. 6 and the charges are accumulated in the capacitor Cf. Similarly, when a negative force -Fz acts in the negative direction of the Z-axis, charges are generated with the opposite polarity to the above but with the circuit shown in FIG. 6, charges are accumulated in the capacitor Cf with the same polarity.

In the description of this embodiment, the electric charges generated by the force in the extension direction and the force in the compression direction are opposite in polarity, but the piezoelectric material layer is made to be a piezoelectric ceramic and polarization control is controlled to obtain the same polarity in extension and compression. It is also possible to generate a charge. Even in this case, the power generation circuit 14 shown in FIG. 6 is effective.

Next, the power generation operation by the power generation device 10 provided with the unit

power generation elements

21, 22, 23 of this embodiment will be described. Since the power generator 10 is composed of the

vibration systems

11, 12, 13 of different natural frequencies as described above, the resonance frequency to the vibration of the external world is different. As shown in FIGS. 8A, 8B, and 8C, the resonance frequency in the X-axis direction of the vibration system 11 is fx1, the resonance frequency in the Y-axis direction is fy1, and the resonance frequency in the Z-axis direction is fz1. I assume. The resonance frequency in the X-axis direction of the vibration system 12 is fx2, the resonance frequency in the Y-axis direction is fy2, and the resonance frequency in the Z-axis direction is fz2. The resonance frequency in the X axis direction of the vibration system 13 is fx3, the resonance frequency in the Y axis direction is fy3, and the resonance frequency in the Z axis direction is fz3. Summarizing the frequency characteristics of the vibration system 11, the vibration system 12, and the vibration system 13, respective resonance frequencies and amplitudes in the X, Y, and Z directions are represented as shown in FIG. Thus, the

vibration systems

11, 12 and 13 of the unit

power generation elements

21, 22 and 23 can resonate at different frequencies with respect to mechanical vibration in a wide band of different frequencies with respect to forces in the XYZ axial directions. The vibration of a wide frequency contributes to the power generation operation, and power can be generated effectively.

According to the power generation device 10 and the unit

power generation elements

21, 22, and 23 of this embodiment, the vibration system 11 of the unit

power generation elements

21, 22, and 23 in response to a wide range of mechanical vibrations of the environment where the power generation device 10 is provided. , 12 and 13 resonate at different frequencies, so that external vibration can be efficiently converted into electrical energy and extracted. Moreover, the direction of external mechanical vibration can also be picked up and resonated in all directions of the XYZ Cartesian coordinate system and converted to electrical energy, so that efficient power generation can be performed from this point as well. . Further, since they are formed symmetrically on the XY plane with respect to the axis in the Y-axis direction, they vibrate efficiently, have a simple structure, and have high strength. Furthermore, the weight body support portion 28 and the weight body 32 are formed to be bent from the distal end portion 26a of the bridge portion 26 and extended to the base end portion 26b, and miniaturization is easy.

Next, a power generation device 36 according to a second embodiment of the present invention will be described based on FIG. Here, the same members as those in the above embodiment are given the same reference numerals, and the description thereof is omitted. The power generation element 36 of this embodiment is a device in which the arrangement of the unit

power generation elements

21, 22, 23 is devised to reduce the overall volume. As shown in FIG. 9, the directions of the unit

power generation elements

21 and 22 and the unit power generation element 23 are reversed, and the dimension in the X axis direction is shortened by the width of the weight 32 in the X axis direction. And space efficiency.

According to the power generation device 36 and the unit

power generation elements

21, 22, and 23 of this embodiment, the same effect as that of the above embodiment can be obtained, and a further compact and efficient power generation device can be provided.

Next, a power generation apparatus 38 according to a third embodiment of the present invention will be described based on FIGS. 10 to 14. Here, the same members as those in the above embodiment are given the same reference numerals, and the description thereof is omitted. The power generation element 38 of this embodiment is, as shown in FIG. 10, an end of the weight body 32 of the unit

power generation elements

21 and 23 facing each other, and a weight body 32 of the unit

power generation elements

22 and 23 facing each other. The end portions of are physically connected by a connecting body 40.

Below, the effect | action by connecting the end parts of the weight body 32 is demonstrated. First, for the sake of simplicity, it is assumed that

basic vibration systems

41 and 42 each having a cantilever shown in FIG. A weight m1 is provided to the basic vibration system 41, and a weight m2 is provided to the basic vibration system 42, and the natural frequencies of the

basic vibration systems

41 and 42 are different. It is assumed that an upper layer electrode E1 is provided in each bridge portion 44 of the

basic vibration systems

41 and 42 via a lower layer electrode E0 and a piezoelectric body 46 (not shown).

The frequency characteristic of the basic vibration system 41 is shown in FIG. 12 (a), and the frequency characteristic of the basic vibration system 42 is shown in FIG. 12 (b). A resonance frequency of the basic vibration system 41 is f1, a peak of amplitude at resonance is Q1, a resonance frequency of the basic vibration system 42 is f2, and a peak of amplitude at resonance is Q2. When the basic vibration system 41 vibrates at its resonance frequency, the peak at resonance becomes Q1 and a large charge is generated in the electrode E1. This charge will disturb the vibration with its own charge. In addition, a large amount of charge or stress generated at the time of resonance may damage the thin film of the piezoelectric body 46 or the mechanical portion of the power generation element.

Similarly, when the basic vibration system 42 vibrates at a resonance frequency, the peak at resonance becomes Q2, a large charge is generated in the electrode E2, and this charge interferes with its own vibration. In addition, a large amount of charge or stress generated at the time of resonance may damage the thin film of the piezoelectric body 46 or the mechanical portion of the power generation element.

In order to suppress the above excessive vibration and acceleration, as shown in FIG. 13, the weight bodies m1 and m2 are physically connected by the connector 40, and the basic vibration system 41 vibrates at the resonance frequency f1. When the vibration is released to the basic vibration system 42, the peak at the time of resonance of the basic vibration system 41 may be lowered, and power may be generated in the basic vibration system 42 as well. Similarly, when the basic vibration system 42 vibrates at the resonance frequency f2, the vibration is released to the basic vibration system 41, the peak at the resonance of the basic vibration system 42 is lowered, and power is generated also in the basic vibration system 41. You should do it. As a result, charges are generated in both of the upper layer electrodes E1 and E2 at one resonance frequency f1, and the generated charges can be output to the power generation circuit 47 and taken out as electric power. In addition, even when a large external force acts, the force can be dispersed in the basic vibration system 42 to prevent breakage. Similarly, charges are generated in both of the upper layer electrodes E1 and E2 by the other resonance frequency f2, and the generated charges can be output to the power generation circuit 14 and taken out as electric power. Moreover, even when a large external force acts, the force can be dispersed to the basic vibration system 41 to prevent breakage.

By connecting the weight bodies m1 and m2 with the connecting body 40, in the

basic vibration systems

41 and 42, power generation which is the amount of generated charge at the frequency f1 of the upper layer electrode E1 as compared with the case without the connecting body 40 Although the amount decreases, as shown in FIG. 14A, the upper layer electrode E2 also generates power. Similarly, at the frequency f2, the amount of power generation in the upper layer electrode E2 decreases, but the upper layer electrode E1 also generates power. Then, if the two electric charges generated on the electrodes E41 and E42 are collected by the power generation circuit 47 to generate power, efficient power generation becomes possible. Moreover, since the amplitude is suppressed at the frequency f1 and the frequency f2, the possibility of breakage of the bridge portion 44 can also be suppressed. When the amplitudes of the weight bodies m1 and m2 are small, the connection by the connecting body 40 does not function so much, but when the amplitudes of the weight bodies m1 and m2 become large, the connection body 40 generates the amplitudes of the

vibration systems

41 and 42. Will be restricted.

The power generation device 38 of this embodiment utilizes this action, and as shown in FIG. 10, the end portions of the weight bodies 32 of the unit

power generation elements

21 and 22 facing each other, and the unit

power generation elements

22 and 23. The end portions of the weight bodies 32 facing each other are physically connected by the connecting member 40 to improve the power generation efficiency and to increase the strength against external force. However, if the vibration systems are mutually coupled too strongly, the above-mentioned power generation capacity is rather suppressed and the power generation efficiency is lowered, so it is necessary to connect the appropriate strength.

According to the power generation device 38 and the unit

power generation elements

21, 22, and 23 of this embodiment, the mechanical vibration of the unit

power generation elements

21, 22, and 23 of the

vibration systems

11, 12, and 13 is the other vibration by the connector 40. Even if one vibration system propagates to the system and generates a large acceleration due to resonance, the mechanical vibration is dispersed to the other vibration systems, the peak value of the amplitude is reduced, and the breakage of the bridge portion 26 is prevented.

Next, a power generation system according to a fourth embodiment of the present invention will be described with reference to FIG. Here, the same members as those in the above embodiment are given the same reference numerals, and the description thereof is omitted. The power generation device of this embodiment is different from the above embodiment in the shape of the unit power generation element 51, and the whole volume can be further reduced.

In the unit power generation element 51 of this embodiment, the weight body 52 is continuous downward from the tip end 26a of the bridge portion 26 in the Z-axis direction, and is separated from the bridge portion 26 by a predetermined distance. One weight body 52 is formed in an L-shape extending toward the end 26b. Therefore, the weight body 52 is located below the bridge portion 26 in the Z-axis direction.

Unlike the weight body 32 of the above embodiment, since the weight body 52 of this embodiment is provided so as to overlap the bridge portion 26 in the Z-axis direction, after being formed separately from the bridge portion 26, L-shaped The one end 52 a of the weight body 52 formed in the above is formed by being joined to the tip 26 a of the bridge 26.

The power generation apparatus of this embodiment also has a structure similar to that of the unit power generation element 51, and is provided with a plurality of unit power generation elements having different natural frequencies, as in the above embodiment. The method of making natural frequency into a different value is the same as that of the said embodiment.

Also by the power generation device of this embodiment and the unit power generation element 51, the same effect as that of the above-described embodiment can be obtained, and a further compact and efficient power generation device can be provided.

The power generation element of the present invention is not limited to the above embodiment. The weight body may have a shape provided with only one of the pair of weight bodies of the first embodiment, whereby the bridge portion becomes asymmetrical with respect to the longitudinal axis in the Y-axis direction, It is possible to further miniaturize the shape of the power generation device. The position of the center of gravity of the weight body is a predetermined distance from the approximate center of the bridge in the Z-axis direction, and is within the projection range of the bridge and parallel to the longitudinal axis at a predetermined distance. If the weight body is asymmetrical, it may be slightly out of the projection range of the bridge portion.

Further, the support frame portion, the bridge portion of the unitary power generation element, and the weight body support portion may be replaced with the above-described materials. The unit power generation element only needs to have flexibility in the bridge portion. The elastic coefficient may be changed for each region of the bridge portion to set the natural frequency, and any method of setting the natural frequency may be used. Absent.

11, 12, 13 Vibration system 14

Power generation circuit

21, 22, 23, 51 Unit power generation element 24 Support frame portion 24 a Inner wall surface 26 Bridge portion 26 a Tip portion 26 b Base end portion 28 Weight mass support portion 30

Piezoelectric material layer

32, 52 Weight body 34 Piezoelectric element E0 Lower layer electrodes E1, E2, E3, and E4 Upper layer electrodes P1, P2, P3, and P4 electric effect unit

Claims

A power generation device comprising a power generation element that generates power by converting mechanical vibration energy into electric energy,
The power generation element is continuous from a bridge portion having a longitudinal axis and having flexibility, a support frame portion to which a base end portion of the bridge portion is fixed, and a tip portion of the longitudinal axis of the bridge portion And a weight body provided bent at the base end side of the bridge portion at a predetermined interval, a piezoelectric element fixed at a predetermined position at which expansion and contraction of the surface of the bridge portion occurs, and the piezoelectric element A plurality of electrodes fixed to the element and outputting the charge generated in the piezoelectric element;
A plurality of the power generation elements are fixed in the support frame portion, and natural frequencies of vibration systems of the respective power generation elements are configured at different frequencies.
A power generation apparatus characterized in that each electrode of each power generation element is connected to a power generation circuit that takes out the charge generated in the piezoelectric element and outputs power.
The power generator according to claim 1, wherein the center of gravity of the weight body is located on an axis parallel to the longitudinal axis at predetermined intervals with respect to the longitudinal axis.
The power generating apparatus according to claim 2, wherein the weight body is bent in a symmetrical shape on both sides of the bridge portion.
The power generation device according to claim 3, wherein vibration systems of the respective power generation elements are set to different natural frequencies because the mass of the weight body is different.
The power generation device according to claim 3, wherein vibration systems of the respective power generation elements are set to different natural frequencies because the elastic coefficients of the bridge portions are different.
The power generating apparatus according to claim 3, wherein the bridge portions of the power generating elements are alternately fixed to opposing inner wall surfaces of the support frame portion and extend parallel to each other on the same plane.
The power generation device according to claim 1, wherein the vibration systems of the power generation elements are physically connected to each other so that one vibration can be transmitted to the other.
The power generation apparatus according to claim 7, wherein the respective weight systems of the respective vibration systems are connected to each other by a coupling body.
A power generation element that generates power by converting mechanical vibration energy into electrical energy,
A flexible bridge section having a longitudinal axis,
A support frame portion to which a base end portion of the bridge portion is fixed;
A weight body which is continuous with the tip of the longitudinal axis of the bridge portion and is bent at the base end side of the bridge portion at a predetermined interval;
A piezoelectric element fixed at a predetermined position where expansion and contraction deformation of the surface of the bridge portion occurs;
And a plurality of electrodes fixed to the piezoelectric element and outputting charges generated in the piezoelectric element;
The center of gravity of the weight body is located on an axis parallel to the longitudinal axis at predetermined intervals with respect to the longitudinal axis.
The weight body is fixed to a weight body supporting portion located in parallel with the bridge portion at a predetermined interval, and a center of gravity of the weight body is located at a predetermined distance from a center of the bridge portion. The power generation element according to claim 9.
The bridge portion and the weight body support portion are formed of the same plate material, a piezoelectric material layer is stacked on one surface of the bridge portion and the weight body support portion, and the weight body is formed on the other surface. The power generation element according to claim 9, wherein the projected shapes of the layer formed of the bridge portion and the weight body support portion, the piezoelectric material layer, and the weight body in the stacking direction are the same.