Vibration power generation device

Abstract

To provide a vibration power generation device that can suppress a reduction of power generation due to temperature change.SOLUTION: A vibration power generation device (10) comprises: a vibration portion (12) capable of vibrating; a fixing portion (13) that fixes the vibration portion in at least two points; a relaxation portion (18) that relaxes a tension which occurs at least in the vibration portion due to a difference between a thermal expansion of the vibration portion and a thermal expansion of the fixing portion by giving an opposite force to the fixing part or the vibration part. For the vibration power generation device, a thermal expansion coefficient of the relaxation portion may be smaller than a thermal expansion coefficient of the vibration portion in the case where the thermal expansion coefficient of the vibration portion is smaller than the thermal expansion coefficient of the fixing portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a vibration power generation device. [Background technology]

[0002] There are known vibration power generation devices that generate electric energy from vibration energy in the surrounding environment, and sensor modules that use vibration power generation devices. For example, Patent Document 1 discloses a power generation element having a structure in which multiple plate-like flexible bodies and a weight body are combined. In addition, for example, Patent Document 2 discloses a power generation device that includes multiple piezoelectric elements and a connecting member that connects the multiple piezoelectric elements, and can efficiently convert vibration energy into electric energy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-103170 A [Patent Document 2] JP 2020-061938 A Summary of the Invention [Problem to be solved by the invention]

[0004] In vibration power generation devices, the thermal expansion coefficients of the vibrating part and the fixed part that fixes the vibrating part often differ, so that when tension is applied to the vibrating part due to changes in temperature, the resonant frequency changes and the amount of power generated decreases.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a vibration power generation device that can suppress a decrease in the amount of power generation caused by temperature changes. [Means for solving the problem]

[0006] (1) A vibration power generation device according to an embodiment of the present disclosure, A vibration part capable of vibrating; A fixing part that fixes the vibration part at at least two points; The vibration device further includes a relaxation section that relaxes tension generated in at least the vibration section due to a difference in thermal expansion between the vibration section and the fixed section by applying a force in an opposite direction to the fixed section or the vibration section.

[0007] (2) As an embodiment of the present disclosure, in (1), When the thermal expansion coefficient of the vibration portion is smaller than that of the fixed portion, the thermal expansion coefficient of the relaxation portion is smaller than that of the vibration portion.

[0008] (3) As an embodiment of the present disclosure, in (1), When the thermal expansion coefficient of the vibration portion is greater than the thermal expansion coefficient of the fixed portion, the thermal expansion coefficient of the relaxation portion is greater than the thermal expansion coefficient of the vibration portion.

[0009] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The relaxation section includes two or more layers having different thermal expansion coefficients.

[0010] (5) As an embodiment of the present disclosure, in any one of (1) to (4), The buffer portion is provided between the fixed portion and the vibrating portion.

[0011] (6) As an embodiment of the present disclosure, in any one of (1) to (4), The relaxation portion is provided on the outer side of the fixed portion.

[0012] (7) As an embodiment of the present disclosure, in any one of (1) to (4), The relaxation portion is provided on the inner side of the fixed portion.

[0013] (8) As an embodiment of the present disclosure, in any one of (1) to (4), The relaxation portion is a part or the whole of the upper surface of the fixed portion and the bottom surface of the fixed portion.

[0014] (9) As an embodiment of the present disclosure, in any one of (1) to (4), The relaxation portion is provided inside the fixed portion.

[0015] (10) As an embodiment of the present disclosure, in any one of (1) to (4), The buffer portion is provided on a side surface of the vibration portion. Effect of the Invention

[0016] According to the present disclosure, it is possible to provide a vibration power generation device that can suppress a decrease in the amount of power generation caused by temperature changes. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a functional block diagram showing a schematic configuration of a sensor module including a vibration power generation device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view taken along the vibration direction of a vibration power generation device according to an embodiment of the present disclosure. [Figure 3A] FIG. 3A is a cross-sectional view for explaining the difference in thermal expansion between the vibrating portion, the fixed portion, and the relaxation portion. [Figure 3B] FIG. 3B is a cross-sectional view for explaining the difference in thermal expansion between the vibrating portion, the fixed portion, and the relaxation portion. [Figure 4] FIG. 4 is a diagram showing an example of the arrangement of the damping parts relative to the vibrating part and the fixed part in the vibration power generation device. [Figure 5A] FIG. 5A is a diagram showing an example of the arrangement of the damping parts relative to the vibrating part and the fixed part in a vibration power generation device. [Figure 5B] FIG. 5B is a diagram showing an example of the arrangement of the relaxation part relative to the vibrating part and the fixed part in the vibration power generation device. [Figure 6A] FIG. 6A is a diagram showing an example of the arrangement of the relaxation parts relative to the vibrating part and the fixed part in a vibration power generation device. [Figure 6B] FIG. 6B is a diagram showing an example of the arrangement of the relaxation part relative to the vibrating part and the fixed part in the vibration power generation device. [Figure 7] FIG. 7 is a diagram showing an example of the arrangement of the damping parts relative to the vibrating part and the fixed part in the vibration power generation device. [Figure 8] FIG. 8 is a diagram showing an example of the arrangement of the damping parts relative to the vibrating part and the fixed part in the vibration power generation device. [Figure 9] FIG. 9 is a diagram showing an example of the arrangement of the damping parts relative to the vibrating part and the fixed part in a vibration power generation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a vibration power generation device according to an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate. However, the drawings are schematic. For example, the relationship between thickness and width is different from the actual one. In addition, the embodiment shown below is an example of a device for embodying the technical idea of ​​the present disclosure, and the shape, structure, arrangement, etc. of the components are not limited to those described below.

[0019] 1 is a functional block diagram showing a schematic configuration of a sensor module 21 including a vibration power generation device 10 according to this embodiment. The sensor module 21 includes a sensor 22, a communication unit 23, a controller 24, and the vibration power generation device 10. The sensor module 21 may detect various conditions without receiving power from an external source and transmit the detection results to an external device. The sensor module 21 is used in, for example, bridges, trains, vehicles, power plants, outdoor machinery, factory equipment, etc.

[0020] The sensor 22 is, for example, a vibration sensor, a temperature sensor, a pressure sensor, etc., and detects an arbitrary state of an arbitrary object. The sensor 22 is driven by power supplied from the vibration power generation device 10.

[0021] The communication unit 23 is an interface that communicates with an external device via a network. The communication unit 23 may include, for example, a communication module that communicates with an external device via a network. The communication unit 23 transmits, for example, a detection value indicating an arbitrary state detected by the sensor 22 to the external device as a signal. Here, the detection value is a numerical representation of the detection result. The communication unit 23 may receive a command from the external device and transmit it to the controller 24. The communication unit 23 is driven by power supplied from the vibration power generation device 10.

[0022] The controller 24 controls the operation of the sensor 22 and the communication unit 23. For example, the controller 24 may be configured to include one or more processors and a memory. The processor may include a general-purpose processor that loads a specific program to execute a specific function and a dedicated processor specialized for a specific process. The dedicated processor may include an application specific integrated circuit (ASIC). The processor may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The controller 24 may be either a system-on-a-chip (SoC) or a system in a package (SiP) in which one or more processors work together. The controller 24 is driven by power supplied from the vibration power generation device 10.

[0023] 2 is a cross-sectional view along the vibration direction of the vibration power generation device 10 according to this embodiment. The vibration power generation device 10 includes a weight portion 11, a vibration portion 12, a piezoelectric portion 17, a relaxation portion 18, and a fixing portion 13. The vibration power generation device 10 may further include a housing 14. In this embodiment, the housing 14 functions as the fixing portion 13.

[0024] Plummet 11 applies an inertial force to increase the vibration of vibration section 12 supported by fixed section 13. Plummet 11 may be provided on a surface of vibration section 12 on the vibration direction side determined as the direction in which vibration is to be caused.

[0025] Here, FIG. 2 shows orthogonal coordinates. These orthogonal coordinates are also used in FIG. 3A to FIG. 9, which will be referred to later. The z-axis direction is the direction in which the weight part 11 vibrates during normal use, that is, the vibration direction. The z-axis direction is also the thickness direction (height direction) of the vibration power generation device 10. The x-axis direction corresponds to the width direction of the vibration power generation device 10. The y-axis direction corresponds to the depth direction of the vibration power generation device 10. In the following, the relative positional relationship may be described with the positive z-axis direction being the top and the negative z-axis direction being the bottom. For example, of the surfaces of the fixed part 13 and the vibrating part 12, the surface located at the top (positive z-axis side) is referred to as the top surface. For example, of the surfaces of the fixed part 13 and the vibrating part 12, the surface located at the bottom (negative z-axis side) is referred to as the bottom surface or bottom surface. For example, of the surfaces of the fixed part 13 and the vibrating part 12, the surface connecting the top surface and the bottom surface may be referred to as the side surface.

[0026] Each of the components of the vibration power generation device 10 will be described below. The weight section 11 may have a main body section 15 and a neck section 16. The main body section 15 is, for example, plate-shaped. The neck section 16 may be columnar, such as a cylinder, and thinner than the main body section 15. The axis of the neck section 16 may pass through the center of the main body section 15 and be perpendicular to the plate-shaped main body section 15. The neck section 16 may be fixed to the vibration section 12 so that the axis is parallel to the vibration direction.

[0027] The vibration part 12 may be, for example, a thin plate, with the plate surface perpendicular to the vibration direction. The shape of the vibration part 12 is not limited as long as it can vibrate. For example, the vibration part 12 may be not only plate-shaped, but also cross-shaped, a cross extending in a diagonal direction, circular, polygonal, or spherical. The vibration part 12 may be a substrate having wiring for electrical connection. The vibration part 12 may be made of metal or resin. The vibration part 12 may be made of, for example, SUS or the like.

[0028] The piezoelectric portion 17 is provided on the vibrating portion 12. The piezoelectric portion 17 may be disposed at a position where stress is generated by vibration of the vibrating portion 12. The piezoelectric portion 17 may be provided on the surface of the vibrating portion 12 on the vibration direction side. A plurality of piezoelectric portions 17 may be provided so as to be aligned along the extending direction of the vibrating portion 12. A plurality of piezoelectric portions 17 may be provided on the surfaces on both sides of the vibrating portion 12 in the vibration direction. In other words, a plurality of piezoelectric portions 17 may be provided on the top and bottom surfaces of the vibrating portion 12.

[0029] The piezoelectric section 17 includes a piezoelectric body and an electrode. When the vibrating section 12 deforms due to vibration, the piezoelectric section 17 deforms together with the vibrating section 12. As a result, when the vibrating section 12 vibrates, stress is applied to the piezoelectric body in the piezoelectric section 17, and this stress is converted into electricity by the piezoelectric effect of the piezoelectric body. The electricity generated by the piezoelectric body is output to the outside of the vibration power generation device 10 via the electrode.

[0030] The fixing part 13 fixes the vibration part 12 by any method. The fixing part 13 fixes the vibration part 12 at least at two points. Here, "the fixing part 13 fixes the vibration part 12" includes not only the case where the fixing part 13 directly fixes the vibration part 12, but also the case where the fixing part 13 fixes the vibration part 12 via another member such as the buffer part 18. The fixing part 13 is preferably formed of a member with high rigidity, and may be formed of, for example, a simple metal such as Fe, an alloy containing Fe, Ni, Cr, or the like, or a nonmetallic material such as SUS or resin. In this embodiment, a part of the housing 14 that houses the weight part 11 and the vibration part 12 functions as the fixing part 13.

[0031] In a device that generates vibration power, the thermal expansion coefficients of the vibration member and the fixing member that fixes the vibration member are often different. Therefore, the fixing member may pull the vibration member or loosen it in response to a change in temperature (for example, from a low temperature to a high temperature). In other words, the tension of the vibration part 12 changes depending on the change in temperature. In vibration power generation, power can be generated efficiently by the vibration member vibrating at a predetermined resonance frequency, but it is known that the resonance frequency changes in proportion to the square root of the tension. In the past, for example, when the temperature changed to a high temperature and the tension applied to the vibration member increased, the resonance frequency shifted to a high frequency side, and the amount of power generation decreased.

[0032] The relaxation section 18 provided in the vibration power generation device 10 according to this embodiment relaxes the tension generated in at least the vibration section 12 due to the difference between the thermal expansion of the vibration section 12 and the thermal expansion of the fixed section 13 by applying a force in the opposite direction to the fixed section 13 or the vibration section 12. Here, the difference in thermal expansion is obtained from the difference in the thermal expansion coefficients of the vibration section 12 and the fixed section 13. For example, the linear expansion coefficient can be used as the thermal expansion coefficient. The linear expansion coefficient (α[1 / °C]) can be calculated by α=(Δl / Δt)×(1 / L). Here, Δl[m] is the amount of change in length. Δt[°C] is the amount of change in temperature. Also, L[m] is the length.

[0033] 3A and 3B are cross-sectional views for explaining the difference in thermal expansion between the vibration part 12, the fixed part 13, and the relaxation part 18. In FIG. 3A, FIG. 3B, and FIG. 4 to FIG. 9 to be referred to later, the weight part 11 and the piezoelectric part 17 shown in FIG. 2 are omitted for ease of viewing. In FIG. 3A and FIG. 3B, α(12), α(13), and α(18) respectively mean the linear expansion coefficient of the vibration part 12, the linear expansion coefficient of the fixed part 13, and the linear expansion coefficient of the relaxation part 18. The length of the arrow indicates the relative magnitude of the linear expansion coefficient. When the thermal expansion coefficient of the vibration part 12 is smaller than that of the fixed part 13, the thermal expansion coefficient of the relaxation part 18 is selected to be smaller than that of the vibration part 12. As shown in FIG. 3A, the relaxation part 18 acts to suppress (apply a force in the opposite direction) the large thermal expansion of the fixed part 13. Furthermore, when the thermal expansion coefficient of the vibrating part 12 is greater than that of the fixed part 13, the thermal expansion coefficient of the relaxation part 18 is selected to be greater than that of the vibrating part 12. As shown in FIG. 3B, the thermal expansion of the fixed part 13 is small, but the relaxation part 18 acts to pull (apply a force in the opposite direction). In this way, based on the magnitude relationship between the thermal expansion coefficients of the vibrating part 12 and the fixed part 13, the relaxation part 18 is selected to have an appropriate thermal expansion coefficient. Then, the relaxation part 18 can relax the change in tension on the vibrating part 12 that accompanies a change in temperature, and suppress the change in the resonant frequency of the vibration power generation device 10.

[0034] 3A and 3B, the relaxation portion 18 is provided between the fixed portion 13 and the vibration portion 12. However, the arrangement and configuration of the relaxation portion 18 are not limited to this.

[0035] For example, as shown in Fig. 4, the relaxation section 18 may include two or more layers with different thermal expansion coefficients. When the thermal expansion coefficient of the vibrating section 12 is smaller than that of the fixed section 13, it is preferable that the thermal expansion coefficient of each layer of the relaxation section 18 is selected to be smaller than that of the vibrating section 12. Also, when the thermal expansion coefficient of the vibrating section 12 is larger than that of the fixed section 13, it is preferable that the thermal expansion coefficient of each layer of the relaxation section 18 is selected to be larger than that of the vibrating section 12. By forming the relaxation section 18 from a plurality of layers, it is possible to further enhance the effect of relaxing the change in tension on the vibrating section 12 caused by temperature change.

[0036] For example, as shown in Figs. 5A and 5B, the relaxation portion 18 may be provided on the outside of the fixed portion 13. Here, the inside and outside are defined by their positions relative to the space surrounded by the fixed portion 13, which is the housing 14. The inside is the side of the fixed portion 13 that faces the space. Also, the outside is the side of the fixed portion 13 that does not face the space and is far from the space. As shown in Fig. 5A, the relaxation portion 18 may be provided on the outside of the top surface and the bottom surface of the fixed portion 13. Also, as shown in Fig. 5B, the relaxation portion 18 may be provided on the outside of the side surface of the fixed portion 13. In this configuration, the process of attaching the relaxation portion 18 becomes easier.

[0037] For example, as shown in Figures 6A and 6B, the relaxation portion 18 may be provided on the inside of the fixed portion 13. As shown in Figure 6A, the relaxation portion 18 may be provided on the inside of the top surface and the bottom surface of the fixed portion 13. Also, as shown in Figure 5B, the relaxation portion 18 may be provided on the inside of the side surface of the fixed portion 13. In the case of this configuration, the area of ​​the relaxation portion 18 can be made small, and therefore the amount of material for the relaxation portion 18 can be reduced.

[0038] 7, the relaxation portion 18 may be a part or the whole of the upper surface and the bottom surface of the fixed portion 13. In the case of this configuration, the overall amount of material of the vibration power generation device 10 can be reduced.

[0039] As yet another configuration, the relaxation portion 18 may be provided inside the fixed portion 13, as shown in Fig. 8, for example. Also, the relaxation portion 18 may be provided on the side surface of the vibrating portion 12, as shown in Fig. 9, for example.

[0040] As described above, the vibration power generation device 10 according to this embodiment has the above-mentioned configuration, and the relaxation section 18 relaxes the change in tension on the vibration section 12 caused by temperature change, thereby suppressing the change in the resonance frequency of the vibration power generation device 10. Therefore, the vibration power generation device 10 according to this embodiment can suppress the decrease in the amount of power generation caused by temperature change.

[0041] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or corrections based on the present disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present disclosure.

[0042] In the above embodiment, the sensor module 21 has been described as having the configuration shown in Fig. 1, but it is not necessary to include all of the components. For example, the sensor module 21 may be configured not to include the sensor 22, and the vibration power generation device 10 may also function as the sensor 22. For example, the vibration power generation device 10 may output a signal indicating the strength of vibration together with the power generated by the piezoelectric body in the piezoelectric section 17. For example, the controller 24 may calculate the speed of a moving object on which the sensor module 21 is mounted based on the signal indicating the strength of vibration, thereby realizing the function of a speed sensor. [Explanation of symbols]

[0043] 10. Power-generating vibration device 11 Weight 12 Vibration section 13 Fixed part 14. Chassis 15 Main body 16 neck 17 Piezoelectric section 18 Relaxation section 21 Sensor Module 22 Sensors 23 Communications Department 24 Controller

Claims

1. A vibration part capable of vibrating; A fixing part that fixes the vibration part at at least two points; A vibration power generation device comprising: a relaxation section that relaxes tension generated in at least the vibration section due to a difference between thermal expansion of the vibration section and thermal expansion of the fixed section by applying an opposite force to the fixed section or the vibration section.

2. The vibration power generation device according to claim 1 , wherein when the thermal expansion coefficient of the vibrating portion is smaller than the thermal expansion coefficient of the fixed portion, the thermal expansion coefficient of the relaxation portion is smaller than the thermal expansion coefficient of the vibrating portion.

3. The vibration power generation device according to claim 1 , wherein when the thermal expansion coefficient of the vibrating portion is greater than the thermal expansion coefficient of the fixed portion, the thermal expansion coefficient of the relaxation portion is greater than the thermal expansion coefficient of the vibrating portion.

4. The vibration power generation device according to claim 1 , wherein the relaxation section includes two or more layers having different thermal expansion coefficients.

5. The vibration power generation device according to claim 1 , wherein the relaxation portion is provided between the fixed portion and the vibrating portion.

6. The vibration power generation device according to claim 1 , wherein the buffer portion is provided on an outer side of the fixed portion.

7. The vibration power generation device according to claim 1 , wherein the buffer portion is provided inside the fixed portion.

8. The vibration power generation device according to claim 1 , wherein the buffer portion is a part or an entirety of an upper surface and a bottom surface of the fixed portion.

9. The vibration power generation device according to claim 1 , wherein the buffer portion is provided inside the fixing portion.

10. The vibration power generation device according to claim 1 , wherein the buffer portion is provided on a side surface of the vibrating portion.

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