JP6309698B1 - Power generation device and power generation element - Google Patents

Abstract

It is a power generation device and a power generation element that can convert mechanical vibration energy containing various directional components efficiently into electrical energy and obtain high power generation efficiency, and has a simple structure, high strength, and easy miniaturization. . A bridge portion 26 having a longitudinal axis and having flexibility, and a support frame portion 24 to which a base end portion 26b of the bridge portion 26 is fixed. A weight body 32 is provided which is continuous from the distal end portion 26a of the longitudinal axis of the bridge portion 26 and is bent toward the proximal end portion 26b side of the bridge portion 26 at a predetermined interval. The piezoelectric element 34 is provided at a predetermined position where expansion and contraction of the surface of the bridge portion 26 occurs. The piezoelectric element 34 includes a plurality of electrodes E0, E1, E2, E3, E4. A plurality of power generation elements 21, 22, and 23 are fixed in the support frame portion 24. The natural frequencies of the vibration systems of the power generating elements 21, 22, and 23 are different frequencies.

Description

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

  In recent years, various power generation elements that convert mechanical vibration energy into electrical energy using the piezoelectric effect have been proposed as means for obtaining electrical energy. This type of general power generation element supports a weight body by a cantilever beam having one end fixed, and causes the beam portion to be periodically bent by the vertical vibration of the weight body, and a force generated by this bending is applied to the piezoelectric element. To generate a charge. In such a system, since only one-way vibration energy for vibrating the weight body in the vertical direction can be used, the power generation efficiency is low.

  In addition, a piezoelectric power generation element using MEMS (Micro Electro Mechanical System) technology is also arranged on a silicon substrate, and the force acting on the weight body is transmitted to the piezoelectric element, and mechanical force is applied to the piezoelectric effect. To generate electric power by converting into electric charge. This power generation element is designed in accordance with the resonance frequency of the environment in which it is installed in order to increase power generation efficiency. Furthermore, since the vibrating body is made of Si (silicon) or metal, the resonance frequency peak (Q value) is high, but the half-value width is narrow, so the resonance frequency of the power generation element is set to the vibration frequency of the environment in which it is used. It is necessary 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 having a cantilever structure in which a weight body is bent asymmetrically around the weight body. A piezoelectric body is fixed to a bridge portion that is supported and bent and an electrode is disposed on the piezoelectric body. Thereby, mechanical vibration energy in a plurality of directions orthogonal to each other can be used for power generation, and the power generation efficiency is increased.

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

Japanese Patent No. 5529328 JP 2010-273408 A

  In general, mechanical vibrations of various frequencies are mixed in an environment in which the power generation element is used, and it is not limited to a specific frequency and a specific vibration direction. In addition, there is a problem that the resonance frequency (natural frequency) of a structure made of Si or metal varies depending on external stress or temperature fluctuation. Therefore, even if the resonance frequency of the power generation element is matched with the vibration frequency of the usage environment, there is a problem that the power generation efficiency decreases due to temperature fluctuation or the like, or power generation stops.

  Furthermore, in the case of the structure of the power generation element disclosed in Patent Document 1, it is necessary to make the bridge portion as long and thin as possible in order to generate sufficient engagement in the bridge portion and improve power generation efficiency. However, if the bridge part is made long and thin, the structure becomes large and the mechanical strength decreases, and if excessive vibration is applied during use, the bridge part may be damaged and formed in the piezoelectric element. There were also restrictions on the arrangement of electrodes and weights.

  The power generating element disclosed in Patent Document 2 has a vibration direction limited to a uniaxial direction, and cannot efficiently convert vibrations in various directions in a use environment into electric energy.

  The present invention has been made in view of the above-described background art, and can efficiently convert mechanical vibration energy containing various directional components into electric energy to obtain high power generation efficiency, and has a simple structure. An object of the present invention is to provide a power generation device and a power generation element that are high in strength and easy to downsize.

  The present invention relates to a power generation device including a power generation element that generates power by converting mechanical vibration energy into electric energy, the power generation element having a longitudinal bridge and a flexible bridge portion. And a support frame portion to which a base end portion of the bridge portion is fixed, and a continuous portion from the tip end portion of the longitudinal axis of the bridge portion, and is bent toward the base end portion side of the bridge portion at a predetermined interval. A weight body provided; a piezoelectric element fixed at a predetermined position where expansion and contraction 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. A plurality of the power generation elements are fixed in the support frame portion, and the natural frequency of the vibration system of each power generation element is configured with a different frequency, and each electrode of each power generation element is generated in the piezoelectric element. Electric power is extracted and electric power is output. A power generator connected to the circuit.

  The center of gravity of the weight body is located within the projection range of the bridge portion and on an axis parallel to the longitudinal axis at a predetermined interval. Furthermore, the weight body may be provided by being bent in a symmetrical shape on both sides of the bridge portion as a center.

  The vibration system of each power generating element is set to a different natural frequency due to the mass of the weight body being different. Alternatively, the vibration system of each power generating element may be set to have a different natural frequency due to a difference in elastic coefficient and shape of the bridge portion.

  The vibration systems of the power generation elements are preferably physically connected to each other so that one vibration can be transmitted to the other. In each of the vibration systems, the weight bodies are connected to each other by a connecting body.

  The present invention is also a power generation element that generates power by converting mechanical vibration energy into electrical energy, and has a bridge portion having a longitudinal axis and flexibility, and a base end portion of the bridge portion. A fixed support frame portion, a weight body that is continuous from a distal end portion of the longitudinal axis of the bridge portion and is bent toward a base end portion side of the bridge portion at a predetermined interval; and A piezoelectric element fixed at a predetermined position where expansion and contraction 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, and the center of gravity of the weight body is The power generating element is located on an axis parallel to the longitudinal axis with a predetermined interval within the projection range of the bridge portion.

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

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

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

  Furthermore, according to the power generating element of the present invention, the direction of the mechanical vibration of the outside world can be picked up in all directions of the XYZ Cartesian coordinate system, can be vibrated stably, and can be changed into electric energy, so that the efficiency can be further improved. Power generation. In addition, the power generation device and the power generation element of the present invention are simple in structure, high in strength, and easy to downsize.

1 is a schematic plan view showing a first embodiment of a power generator of the present invention. It is a block diagram which shows the vibration system and power generation circuit of 1st embodiment. It is a disassembled perspective view of the unit electric 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. It is AA sectional drawing of FIG. It is a figure which shows the electric power generation circuit of 1st embodiment. The top view (a) which shows the state where the force Fx of the X-axis direction was added to the unit power generation element of 1st embodiment, the top view (b) which shows the state where the force Fy of the Y-axis direction was added, Z-axis direction It is a top view (c) which shows the state where force Fz was added. The graph (a) which shows the frequency characteristic of the vibration of the X-axis direction of the power generation band of each unit power generation element of the power generator of the first embodiment, the graph (b) which shows the frequency characteristic of the vibration of the Y-axis direction, and the Z-axis direction 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 the graph (a) which shows the frequency characteristic of only one basic vibration system, and the graph (b) which shows the frequency characteristic only of the other basic vibration system for demonstrating the electric power generating apparatus of 3rd embodiment. It is the schematic which shows two basic vibration systems and power generation circuits for demonstrating the electric power generating apparatus of 3rd embodiment. It is the graph (a) which shows the frequency characteristic of one basic vibration system which provided the coupling body of the electric power generating apparatus of 3rd embodiment, and the graph (b) which shows the frequency characteristic of the other basic vibration system. It is the side view (a) and top view (b) which show the unit electric power generation element of the electric power generating apparatus of 4th embodiment of this invention.

  Hereinafter, a first embodiment of a power generator according to the present invention will be described with reference to FIGS. The power generation apparatus 10 of this embodiment includes 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. The vibration systems 11, 12, and 13 have the same configuration and have different natural frequencies depending on the length and mass of each part. First, based on the unit power generation element 21 of the vibration system 11, the basic structure of the unit power generation element 21 of this embodiment will be described below. Here, the description of the direction in the present invention is based on a three-dimensional orthogonal coordinate system in the XYZ axis directions orthogonal to each other, and the XY plane is a horizontal plane, and the Z axis direction is a vertical direction and the vertical direction.

  The unit power generation element 21 includes a bridge portion 26 that is provided so as to protrude integrally in the Y-axis direction from the inner wall surface 24 a of the rectangular frame-shaped hollow support body portion 24 of the power generation device 10. The bridge portion 26 is formed in an elongated rectangle having a constant thickness in the Z-axis direction and a longitudinal axis in the Y-axis direction.

  At the distal end portion 26a of the bridge portion 26, there is an L-shaped weight body support portion 28 extending 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 with respect to the longitudinal axis in the Y-axis direction with the bridge portion 26 therebetween. Each weight support part 28 is integrally formed with the support part 24 from the same plate material as the bridge part 26, and the bridge part 26 and the pair of weight support parts 28 are substantially E-shaped on the XY plane. Is provided. Therefore, the bridge portion 26 and the portion parallel to the Y axis of the weight body support portion 28 extend with a constant interval s. The length of the weight body support portion 28 in the Y-axis direction is shorter than that of the bridge portion 26, and the end portion 28 a of the weight body support portion 28 is located away from the inner wall surface 24 a of the support body portion 24. .

  The material of the support part 24, the bridge part 26, and the weight support part 28 is not ask | required, and it is preferable to form with a silicon | silicone, ceramics, etc. in view of the manufacturing method etc. which are mentioned later. As will be described later, the material of the bridge portion 26 and the weight support portion 28 may be formed to have any property of insulation or conductivity 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 a piezoelectric resin is provided on the upper layer of the bridge portion 26 in the Z-axis direction. It has been. 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 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. The piezoelectric material layer 30 is provided integrally.

  A portion of the piezoelectric material layer 30 laminated on the bridge portion 26 is a portion that functions as the piezoelectric element 34, and on the surface side of the piezoelectric element 34 opposite to the lower layer electrode E0, there are four upper layer electrodes E1, E2, and so on. E3 and E4 are provided. The upper layer electrodes E1, E2, E3, and E4 are stacked at four locations on both ends of the piezoelectric element 34 in the X-axis direction and both ends in the Y-axis direction, and are connected to the power generation circuit 14 together with the lower layer electrode E0. The lower layer electrode E0 is a single common electrode formed on the entire lower surface of the piezoelectric element 34, whereas the upper layer electrodes E1 to E4 are piezoelectric regions in which the piezoelectric effect of the piezoelectric element 34 is generated. It is provided as an electrode formed in the part. As will be described later, the direction of the stress (compression direction and extension direction) applied to each part of the piezoelectric element 34 differs depending on the direction of the external force acting on the unit power generation element 21, and is generated in each piezoelectric effect part of the piezoelectric element 34. This is because the positive or negative charges generated in the upper layer electrodes E1 to E4 are efficiently taken in by the different polarities of the electric fields to be generated.

  Since the weight support portion 28 hardly bends and does not generate stress due to external force, the piezoelectric material layer 30 may not be laminated. Further, the piezoelectric element 34 formed of the piezoelectric material layer 30 may be stacked only 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, the bridge portion 26 and the weight body support portion 28 are laminated in the same shape for reasons such as manufacturing described later.

  A weight body 32 is integrally attached to a lower layer of the weight body support portion 28 in the Z-axis direction. The weight body 32 is integrally attached to the pair of L-shaped weight body support portions 28, and has the same shape as the projected shape in the Z-axis direction in which the pair of L-shaped weight body support portions 28 face each other symmetrically. And it is formed in a 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 portion 32 a of the weight body 32 is located at the same position as the end portion 28 a of the weight body support portion 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 portion 32 a of the weight body 32 does not collide with the inner wall surface 24 a of the support body portion 24.

  Since the weight body 32 is formed in a gate shape along the weight body support portion 28, a space 35 is formed in the lower portion of the bridge portion 26 in the Z-axis direction. 4 and 5, the gravity center position G of the weight body 32 is the center in the X-axis direction of the bridge portion 26, and is downward with a predetermined distance 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 located slightly on the distal end portion 26a side from the center portion.

  As the material of the weight body 32, it is preferable to use a material having a specific gravity as large as possible. For example, a metal such as SUS, iron, copper, and tungsten, ceramics, or glass may be used. Furthermore, as will be described later, when the unit power generation elements 21, 22, and 23 are manufactured using the MEMS technology, the weight body 32 may be manufactured from Si.

  Next, the power generation apparatus 10 including the unit power generation elements 21, 22, and 23 according to this embodiment will be described. As shown in FIG. 1, the power generation apparatus 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 a support 24. The support body portion 24 is formed in a hollow rectangular frame shape, and the unit power generation elements 21, 22, and 23 extend in the Y-axis direction and are positioned on the XY plane inside the support body portion 24. The vibration systems 11, 12, and 13 constituting each unit power generation element 21, 22, and 23 have different natural frequencies and resonate at different frequencies. In this embodiment, since the size of the weight body 32 of the unit power generation elements 21, 22, and 23 is different and the masses thereof are different, different natural frequencies are obtained.

  In addition, in order to make each vibration system 11, 12, and 13 have a different natural frequency, the width and length may be changed so that the elastic coefficient of the bridge portion 26 is different, and the thickness, laminate material, and shape may be changed. good. Further, both the masses of the vibration systems 11, 12, and 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 with reference to 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. Among the piezoelectric elements 34 stacked on the bridge portion 26, the portions facing the upper layer electrodes E1, E2, E3, and E4 and the periphery thereof are portions where the piezoelectric effect is efficiently generated, and 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 part P1 is connected to the anode of the diode D11 that forms the rectifier circuit of the power generation circuit 14 and the cathode of the diode D12, respectively, and the cathode of the diode D11 accumulates charges in the power generation circuit 14. The capacitor Cf is connected to one end, 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 that forms the rectifier circuit of the power generation circuit 14 and the cathode of the diode D22, respectively, and the cathode of the diode D21 is a capacitor that accumulates charges. Connected to one end of Cf, the anode of diode D22 is connected to the other end of capacitor Cf.

  Similarly, the upper layer electrode E3 attached to the piezoelectric effect portion P3 is connected to the anode of the diode D31 that forms the rectifier circuit of the power generation circuit 14 and the cathode of the diode D32, respectively, and the cathode of the diode D31 is a capacitor that accumulates charges. Connected to one end of Cf, the anode of diode D32 is connected to the other end of capacitor Cf.

  Similarly, the upper layer electrode E4 attached to the piezoelectric effect portion P4 is connected to the anode of the diode D41 and the cathode of the diode D42 that form the rectifier circuit of the power generation circuit 14, respectively, and the cathode of the diode D41 is a capacitor that accumulates charges. Connected to one end of Cf, the anode of diode D42 is connected to the other end of capacitor Cf.

  Further, the lower layer electrode E0 is connected to the anode of the diode D01 and the cathode of the diode D02, the cathode of the diode D01 is connected to one end of the capacitor Cf that accumulates charges, 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, E4 by the piezoelectric effect portions P1, P2, P3, P4, they can be stored 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, and E4 of the three unit power generation elements 21, 22, and 23 are similarly connected to the diodes D11 to D42 and connected to the capacitor Cf. As a result, 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.

  Since the power generation apparatus 10 of this embodiment is suitable for a power source of a sensor made by MEMS technology and requires a minute structure, each bridge portion of the support 24 and the unit power generation elements 21, 22, and 23 is required. 26 and the weight body support portion 28 can be made of Si by using a semiconductor circuit forming process. In this case, for example, the thickness of the bridge portion 26 and the weight support portion 28 in the Z-axis direction is about 200 μm, the thickness of the piezoelectric layer 30 is 2 μm, and the thickness of the weight body 32 in the Z-axis direction. The thickness is set to 1000 μm, the thickness of the lower layer electrode E0 and the upper layer electrodes E1 to E4 is set to about 0.01 μm, and the outer shape can be manufactured to a size of about 5 mm × 5 mm. In the manufacturing process, the stacking process such as etching and vapor deposition is repeated in the Z-axis direction. In addition, processes such as printing and sputtering can also be used. In this case, an SOI substrate may be 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 used as the weight body 32.

  In addition, it is also possible to use a metal plate for the support portion 24 and the bridge portions 26 of the unit power generation elements 21, 22, and 23. In that case, a metal plate may be formed into a predetermined shape by etching or the like, and the upper surface of the metal plate functions as the lower layer electrode E0, and a piezoelectric thin film is formed on the metal plate by a sputtering method or a Solgenole method. The upper layer electrode can be formed by printing, vapor deposition, sputtering, or the like using a metal material.

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

  First, a case where a force + Fx in the positive direction of the X axis acts will be described. Since the center of gravity G of the weight body 32 is located substantially in the center of the bridge portion 26 and below the Z-axis direction, the external force + Fx is applied to the piezoelectric element 34 of the bridge portion 26 as shown in FIG. 7A. In addition, the force acts as follows. A force in the compression direction acts on the piezoelectric effect portion P1 facing the upper layer electrode E1, and a force in the expansion direction acts on the piezoelectric effect portion P2 facing the upper layer electrode E2, and the piezoelectric effect facing 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 facing the upper layer electrode E4. As a result, electric fields having opposite polarities are generated in the piezoelectric effect portions P1 and P2, and electric fields having opposite polarities in the piezoelectric effect portions P1 and P3 are also generated in the piezoelectric effect portions P3 and P4. Occur. Then, charges having the same polarity are generated in the upper layer electrodes E1 and E4, and charges having the same polarity and opposite in polarity to the upper layer electrodes E1 and E4 are generated in the upper layer electrodes E2 and E3, respectively. The charges accumulated in the electrodes E0 to E4 are opposite in polarity to the upper layer electrodes E1 and E4 and the upper layer electrodes E2 and E3, but are rectified by the circuit shown in FIG. Can be stored. Similarly, when a negative force -Fx is applied in the negative direction of the X axis, charges are generated in the respective electrodes with the opposite polarity as described above, but the capacitor Cf has the same polarity in the charge shown in FIG. Is accumulated.

  Next, a case where a force + Fy in the Y-axis positive direction acts on the weight body 32 of the unit power generation element 21 will be described. Since the gravity center G of the weight body 32 is located substantially below the center of the bridge portion 26 in the Z-axis direction, when the force + Fy in the Y-axis positive direction is applied, Directional moment acts. As a result, as shown in FIG. 7B, force in the compression direction similarly acts on the piezoelectric effect portions P1, P2, P3, and P4 facing the upper layer electrodes E1, E2, E3, and E4, Electric fields having the same polarity are generated. As a result, charges are generated with the same polarity in each of the upper layer electrodes E1, E2, E3, E4, and are rectified by the circuit shown in FIG. 6, and are stored in the capacitor Cf. Similarly, when a negative force -Fy is applied in the negative Y-axis direction, charges are generated with the opposite polarity to the above, but charges are stored in the capacitor Cf with the same polarity by the circuit shown in FIG.

  Next, a case where a force + Fz in the positive Z-axis direction acts on the weight body 32 of the unit power generation element 21 will be described. Since the center of gravity G of the weight body 32 is located substantially below the center of the bridge portion 26 in the Z-axis direction, as shown in FIG. 7C, the piezoelectric effect portion facing each of the upper-layer electrodes E1, E2. A force in the extension direction acts on P1 and P2 to generate electric fields having the same polarity, and charges are generated on the 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 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. In this case, a charge having a polarity opposite to that of the upper layer electrodes E1 and E2 is generated, but the charge is rectified by the circuit shown in FIG. 6 and accumulated in the capacitor Cf. Similarly, when a negative force -Fz is applied in the negative Z-axis direction, charges are generated with the opposite polarity as described above, but charges are stored in the capacitor Cf with the same polarity by the circuit shown in FIG.

  In the description of this embodiment, the charges generated by the force in the extension direction and the force in the compression direction have opposite polarities, but the piezoelectric material layer is made of piezoelectric ceramics, and the polarization process is controlled, so that the same polarity is applied to the 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 apparatus 10 including the unit power generation elements 21, 22, and 23 according to this embodiment will be described. Since the power generation apparatus 10 includes the vibration systems 11, 12, and 13 having different natural frequencies as described above, the resonance frequency with respect to vibrations in the outside 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. And 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. When the frequency characteristics of the vibration system 11, the vibration system 12, and the vibration system 13 are summarized, the respective resonance frequencies and amplitudes in the XYZ axis directions are expressed as shown in FIG. As a result, 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 vibrations in a wide band of different frequencies for each force in the XYZ axial directions. In addition, vibrations of a wide range of frequencies contribute to the power generation operation and can generate power 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 corresponds to a wide range of mechanical vibrations in the environment in which the power generation device 10 is provided. , 12 and 13 resonate at different frequencies, and external vibrations can be efficiently converted into electrical energy and extracted. In addition, the direction of mechanical vibrations in the external world can be picked up and resonated by picking up vibrations in all directions of the XYZ Cartesian coordinate system, and can be changed into electric energy, so that efficient power generation can be performed from this point. . Further, since it is formed in a symmetric shape around the axis in the Y-axis direction on the XY plane, it vibrates efficiently, has a simple structure and high strength. Furthermore, the weight support portion 28 and the weight body 32 are formed in a structure that bends from the distal end portion 26a of the bridge portion 26 and extends to the proximal end portion 26b, and can be easily downsized.

  Next, a power generator 36 according to a second embodiment of the present invention will be described with reference to FIG. Here, the same members as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. The power generating element 36 of this embodiment has a reduced overall volume by devising the arrangement of the unit power generating elements 21, 22, and 23. As shown in FIG. 9, the direction of the Y axis direction of the unit power generation elements 21 and 22 and the unit power generation element 23 is reversed, and the dimension in the X axis direction is shortened by the width of the weight body 32 in the X axis direction. , Which is more space efficient.

  According to the power generation device 36 and the unit power generation elements 21, 22, and 23 of this embodiment, the same effects as those of the above-described embodiment can be obtained, and a smaller and more efficient power generation device can be provided.

  Next, a power generator 38 according to a third embodiment of the present invention will be described with reference to FIGS. Here, the same members as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 10, the power generation element 38 of this embodiment includes the end portions of the weight bodies 32 facing each other of the unit power generation elements 21 and 23 and the weight bodies 32 of the unit power generation elements 22 and 23 facing each other. These end portions are physically connected by a connecting body 40.

  Below, the effect | action by connecting the edge parts of the weight body 32 is demonstrated. First, for simplification, basic vibration systems 41 and 42 using cantilever beams shown in FIG. 11 are assumed. The basic vibration system 41 is provided with a weight body m1, and the basic vibration system 42 is provided with a weight body m2. The natural vibration frequencies of the basic vibration systems 41 and 42 are different. It is assumed that each bridge portion 44 of the basic vibration systems 41 and 42 is provided with a lower layer electrode E0 (not shown) and an upper layer electrode E1 via a piezoelectric body 46.

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

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

  In order to suppress the excessive vibration and acceleration as described above, the weight bodies m1 and m2 are physically connected by the connecting body 40 as shown in FIG. 13, and the basic vibration system 41 vibrates at the resonance frequency f1. At that time, the vibration may be released to the basic vibration system 42, the peak at the time of resonance of the basic vibration system 41 may be lowered, and the basic vibration system 42 may generate power. 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 during resonance of the basic vibration system 42 is lowered, and the basic vibration system 41 also generates power. You can do it. Thereby, electric charges are generated in both the upper layer electrodes E1 and E2 by one resonance frequency f1, and the generated electric charges can be output to the power generation circuit 47 and taken out as electric power. Moreover, even when a large external force is applied, the force can be distributed to the basic vibration system 42 to prevent breakage. Similarly, electric charges are generated in both upper layer electrodes E1 and E2 by other resonance frequencies f2, and the generated electric charges can be output to the power generation circuit 14 and taken out as electric power. Moreover, even when a large external force is applied, the force can be distributed to the basic vibration system 41 to prevent breakage.

  By connecting the weight bodies m1 and m2 with the connecting body 40, the basic vibration systems 41 and 42 generate electric power that is the amount of generated charges at the frequency f1 of the upper electrode E1 as compared with the case where the connecting body 40 is not provided. Although the amount decreases, as shown in FIG. 14A, power is also generated by the upper electrode E2. Similarly, at the frequency f2, the power generation amount at the upper layer electrode E2 decreases, but the upper layer electrode E1 also generates power. If the electric power generation circuit 47 collects both electric charges generated at the electrodes E41 and E42 to generate electric power, efficient electric power generation is possible. In addition, since the amplitude is suppressed at the frequency f1 and the frequency f2, the possibility of damage to the bridge portion 44 is also suppressed. When the weights m1 and m2 have a small amplitude, the connection by the connecting body 40 does not function so much. However, when the weights m1 and m2 have a large amplitude, the connecting body 40 increases the amplitude of the vibration systems 41 and 42. Come to limit.

  The power generation device 38 of this embodiment utilizes this action. As shown in FIG. 10, the end portions of the weight bodies 32 facing each other of the unit power generation elements 21 and 22 and the unit power generation elements 22 and 23. The ends of the weight bodies 32 facing each other are physically connected by the connecting body 40 to improve the power generation efficiency and the strength against external force. However, if the mutual vibration systems are coupled too strongly, the power generation capacity is reduced and the power generation efficiency is lowered. Therefore, connection with appropriate strength is required.

  According to the power generation device 38 and the unit power generation elements 21, 22, and 23 of this embodiment, the mechanical power generation between the unit power generation elements 21, 22, and 23 of the vibration systems 11, 12, and 13 is caused by the coupling body 40. Even if one vibration system generates a large acceleration due to resonance, the mechanical vibration is distributed to other vibration systems to reduce the peak value of the amplitude and prevent the bridge portion 26 from being damaged.

  Next, a power generator 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 denoted by the same reference numerals, and the description thereof is omitted. In the power generation device of this embodiment, the shape of the unit power generation element 51 is different from that of the above embodiment, and the entire volume can be further reduced.

  In the unit power generation element 51 of this embodiment, the weight body 52 is continuous downward from the distal end portion 26a of the bridge portion 26 in the Z-axis direction, and is spaced apart from the bridge portion 26 by a predetermined distance and further in the Y-axis direction. One weight body 52 is formed in an L shape extending to the end portion 26b side. 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, the weight body 52 of this embodiment is provided so as to overlap with the bridge portion 26 in the Z-axis direction. One end portion 52 a of the weight body 52 formed in the above is joined to the tip end portion 26 a of the bridge portion 26.

  The power generation apparatus of this embodiment is also provided with a plurality of unit power generation elements having the same structure as that of the unit power generation element 51 and having different natural frequencies inside the support frame portion as in the above embodiment. The method of setting the natural frequency to a different value is the same as in the above embodiment.

  Also by the power generation device and the unit power generation element 51 of this embodiment, an effect similar to that of the above-described embodiment can be obtained, and a more compact and efficient power generation device can be provided.

  The power generating element of the present invention is not limited to the above embodiment. The weight body may have a shape including only one of the pair of weight bodies of the first embodiment, whereby the bridge portion has an asymmetric shape with respect to the longitudinal axis in the Y-axis direction. It is possible to further reduce the shape of the power generation device. The center of gravity of the weight body is located at a predetermined distance from the center of the bridge portion in the Z-axis direction, and is within the projection range of the bridge portion and parallel to the longitudinal axis at a predetermined interval. However, when the weight body is asymmetrical, it may be slightly deviated from the projection range of the bridge portion.

  Moreover, you may replace the support frame part, the bridge | bridging part of a unit power generation element, and a weight support part other than the above-mentioned raw material. The unit power generation element only needs to have flexibility in the bridge portion, and the natural frequency may be set by changing the elastic coefficient for each region of the bridge portion. Absent.

11, 12, 13 Vibration system 14 Power generation circuit 21, 22, 23, 51 Unit power generation element 24 Support frame portion 24a Inner wall surface 26 Bridge portion 26a Tip portion 26b Base end portion 28 Weight body support portion 30 Piezoelectric material layers 32, 52 Weight 34 Piezoelectric element E0 Lower layer electrode E1, E2, E3, E4 Upper layer electrode P1, P2, P3, P4

Claims (10)

A power generation device including a power generation element that generates power by converting mechanical vibration energy into electrical energy,
The power generating element is fixed to a flexible bridge portion having a longitudinal axis, a support frame portion to which a base end portion of the bridge portion is fixed, and a distal end portion of the longitudinal axis of the bridge portion. A weight body bent to a base end side of the bridge portion at a predetermined interval, a piezoelectric element fixed at a predetermined position where expansion and contraction of the surface of the bridge portion occurs, and the piezoelectric element And a plurality of electrodes for outputting charges generated in the piezoelectric element,
The weight bodies are provided in pairs with symmetrical shapes on both sides of the bridge portion around the longitudinal axis, and the pair of weight bodies are opposite to the surface on which the electrodes are provided. Provided on the back side of the bridge part, and provided in parallel with the bridge part in an E-shape, and the center of gravity of the weight body is spaced apart from the longitudinal axis by a predetermined distance, and the back side of the bridge part Located on the side
A plurality of the power generation elements are fixed in the support frame portion, and the natural frequency of the vibration system of each power generation element is configured at different frequencies,
Each of the electrodes of each of the power generation elements is connected to a power generation circuit that extracts electric charges generated in the piezoelectric elements and outputs electric power. A power generation device including a power generation element that generates power by converting mechanical vibration energy into electrical energy,
The power generating element is fixed to a flexible bridge portion having a longitudinal axis, a support frame portion to which a base end portion of the bridge portion is fixed, and a distal end portion of the longitudinal axis of the bridge portion. A weight body bent to a base end side of the bridge portion at a predetermined interval, a piezoelectric element fixed at a predetermined position where expansion and contraction of the surface of the bridge portion occurs, and the piezoelectric element And a plurality of electrodes for outputting charges generated in the piezoelectric element,
The weight body is provided in parallel to the bridge portion on the back side of the bridge portion on the opposite side of the surface on which the electrode is provided with the bridge portion as a center, and the gravity center of the weight body is Located within the projection range of the bridge portion on an axis parallel to the longitudinal axis at a predetermined interval,
A plurality of the power generation elements are fixed in the support frame portion, and the natural frequency of the vibration system of each power generation element is configured at different frequencies,
Each of the electrodes of each of the power generation elements is connected to a power generation circuit that extracts electric charges generated in the piezoelectric elements and outputs electric power.   The bridge portion and the weight body support portion are formed of the same plate material, a piezoelectric material layer is laminated 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 device according to claim 1, wherein the projection shape of the layer formed by stacking the bridge portion and the weight body support portion, the piezoelectric material layer, and the weight body in the stacking direction is the same.   The power generation device according to claim 1 or 2, wherein the vibration system of each power generation element is set to have a different natural frequency due to a difference in mass of the weight body.   3. The power generation device according to claim 1, wherein the vibration system of each power generation element is set to have a different natural frequency due to a difference in elastic coefficient of the bridge portion.   3. The power generation device according to claim 1, wherein the bridge portions of the power generation elements are alternately fixed to the opposing inner wall surfaces of the support frame portion and extend parallel to each other on the same plane.   3. The power generation device according to claim 1, wherein the vibration systems of the power generation elements are physically connected to each other by a coupling body, and one vibration can be transmitted to the other.   3. The power generation device according to claim 1, wherein the electrodes are provided at four positions on both sides of the longitudinal axis of the bridge portion and stacked on both ends of the piezoelectric element along the longitudinal axis. . A power generation element that generates power by converting mechanical vibration energy into electrical energy,
A flexible bridge portion having a longitudinal axis;
A support frame portion to which a base end portion of the bridge portion is fixed;
A weight body fixed to a distal end portion of the longitudinal axis of the bridge portion and bent to a proximal end side of the bridge portion with a predetermined interval;
A piezoelectric element fixed at a predetermined position where expansion and contraction of the surface of the bridge portion occurs;
A plurality of electrodes fixed to the piezoelectric element and outputting charges generated in the piezoelectric element;
The weight body is bent on the back surface side of the bridge portion opposite to the surface on which the electrode is provided, and is located on an axis parallel to the longitudinal axis at a predetermined interval, The power generation element according to claim 1, wherein a center of gravity of the weight body is located on an axis parallel to the longitudinal axis within a projection range of the bridge portion at a predetermined interval.   The power generation element according to claim 9, wherein the electrodes are provided at four positions on both sides of the longitudinal axis of the bridge portion and stacked on both ends of the piezoelectric element along the longitudinal axis.

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