Vibration power generation device and sensor module

Abstract

To provide a vibration power generation device and a sensor module in which vibration in a twisting mode is less likely to occur even if the weight of a weight member is increased.SOLUTION: A vibration power generation device (10) comprises: a weight member (11); and a plurality of beam parts (12) having connection parts (19) connected to the weight member. The beam parts are positioned on the same plane, and are located so as to surround a center of gravity of the weight member. Distances between the center of gravity of the weight member and the individual connection parts are equal. In the vibration power generation device, the connection parts may be positioned such that they are vertices of a regular polygon.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a vibration power generation device and a sensor module. [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] Here, in a vibration power generation device, increasing the weight of the weight may cause a torsion mode to occur, resulting in a decrease in the amount of power generation.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a vibration power generation device and a sensor module in which torsional mode vibration is unlikely to occur even if the weight of the weight is increased. [Means for solving the problem]

[0006] (1) A vibration power generation device according to an embodiment of the present disclosure, A weight portion and a plurality of beam portions each having a connection portion connected to the weight portion, the plurality of beam portions are each located on the same plane and are located so as to surround the center of gravity of the weight portion, The distances between the centers of gravity of the weight portions and the connecting portions are all equal.

[0007] (2) As an embodiment of the present disclosure, in (1), The connection portions are positioned to become vertices of a regular polygon.

[0008] (3) As an embodiment of the present disclosure, in (1) or (2), The beams all have the same length.

[0009] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The number of the beam portions is three, The connection portions are located so as to become vertices of an equilateral triangle.

[0010] (5) As an embodiment of the present disclosure, in any one of (1) to (3), The number of the beam portions is four, The connection portions are located at the vertices of a square.

[0011] (6) As an embodiment of the present disclosure, in any one of (1) to (3), The number of the beam portions is five, The connection portions are located at the vertices of a regular pentagon.

[0012] (7) As an embodiment of the present disclosure, in any one of (1) to (3), The number of the beam portions is six, The connection portions are located at the vertices of a regular hexagon.

[0013] (8) A sensor module according to an embodiment of the present disclosure includes: A weight portion and a plurality of beam portions each having a connection portion connected to the weight portion, the plurality of beam portions are each located on the same plane and are located so as to surround the center of gravity of the weight portion, The distances between the centers of gravity of the weight portions and the connecting portions are all equal. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a vibration power generation device and a sensor module in which torsional mode vibration is unlikely to occur even if the weight of the weight is increased. [Brief description of the drawings]

[0015] [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. [Diagram 3] FIG. 3 is a perspective view showing the configuration of the weight and beam of the vibration power generation device of FIG. [Figure 4] FIG. 4 is a top view showing the configuration of the weight and beam of the vibration power generation device of FIG. [Diagram 5] FIG. 5 is a top view showing another configuration of the weight and beam of the vibration power generation device. [Figure 6] FIG. 6 is a perspective view showing the configuration of a weight and a beam of a vibration power generation device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a vibration power generation device and a sensor module 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 embodiments shown below are examples of devices for embodying the technical ideas of the present disclosure, and the shapes, structures, arrangements, etc. of the components are not limited to those described below.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Fig. 2 is a cross-sectional view taken along the vibration direction of the vibration power generation device 10 according to this embodiment. Fig. 2 corresponds to the cross section of the vibration power generation device 10 taken along line AA in Fig. 4. The vibration power generation device 10 includes a weight portion 11, a plurality of beam portions 12, a piezoelectric portion 17, and a fixed portion 13. The vibration power generation device 10 may further include a housing 14.

[0022] Plummet 11 applies an inertial force to increase the vibration of beam 12 supported by fixed portion 13. Plummet 11 may be provided on a surface of beam 12 on the vibration direction side determined as the direction in which beam 12 is to vibrate.

[0023] Here, FIG. 2 shows orthogonal coordinates. These orthogonal coordinates are also used in FIG. 3 to FIG. 6, which will be referred to later. The z-axis direction is the direction in which the weight 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 by assuming that the position in the positive direction of the z axis is the top and that the position in the negative direction of the z axis is the bottom. For example, in FIG. 2, the fixed part 13 is located above and below the beam part 12 and supports the fixed part 13. In addition, FIG. 2 shows a plane S. The plane S is a virtual plane that is at the position (height) of the beam part 12 when the weight part 11 is not vibrating, and is parallel to the xy plane.

[0024] Weight portion 11 may have a body portion 15 and a neck portion 16. Body portion 15 is, for example, plate-shaped. Neck portion 16 may be columnar, such as a cylinder, and thinner than body portion 15. The axis of neck portion 16 may pass through the center of body portion 15 and be perpendicular to the plate-shaped body portion 15. Neck portion 16 may be fixed to beam portion 12 so that the axis is parallel to the vibration direction.

[0025] FIG. 3 is a perspective view showing the configuration of the weight 11 and the beams 12 of the vibration power generation device 10. FIG. 4 is a top view showing the configuration of the weight 11 and the beams 12 of the vibration power generation device 10. In FIG. 3 and FIG. 4, the fixing portion 13, the housing 14, and the piezoelectric portion 17 shown in FIG. 2 are shown in a transparent manner for ease of viewing. As shown in FIG. 3, in this embodiment, the number of the beams 12 is four. As shown in FIG. 4, the length of each of the beams 12 is equal to Lb, and the end of each of the beams 12 is connected to the end of the adjacent beam 12, so that the beams 12 have a square shape as a whole. As shown in FIG. 3, each of the beams 12 has a connection portion 19 connected to the weight 11. In this embodiment, the beams 12 are sandwiched between the upper and lower main bodies 15, and the main body 15 of the weight 11 and the beams 12 are in contact with each other at the connection portion 19.

[0026] As shown in FIG. 4, in the vibration power generation device 10 according to this embodiment, each of the beams 12 is located on the same plane (corresponding to the plane S in FIG. 2) and is located so as to surround the center of gravity G of the weight 11. In addition, in the vibration power generation device 10, the distance between the center of gravity G of the weight 11 and the connection portion 19 is configured to be equal. Here, the connection portion 19 has a constant size, and the distance between the center of gravity G and the connection portion 19 is measured using the position of the connection portion 19 closest to the center of gravity G. As shown in FIG. 4, the distance between the center of gravity G and the connection portion 19 of each of the four beams 12 is La and is equal. The connection portions 19 of the beams 12 are located so as to be vertices of a regular polygon having a shape according to the number of the beams 12. The moment around the center of gravity G is zero when the connection portions 19 are located at the vertices of the regular polygon. In other words, three or more vertices may be selected from the vertices of the regular polygon so that the moment around the center of gravity G is zero. In this embodiment, the number of beam portions 12 is four, and the connection portions 19 are positioned to form vertices of a square.

[0027] Hereinafter, each of the components of the vibration power generation device 10 will be described. First, the beam portion 12 may be a thin plate whose plate surface is perpendicular to the vibration direction. The beam portion 12 may be made of a metal such as SUS.

[0028] The piezoelectric portion 17 is provided on each of the multiple beam portions 12. The piezoelectric portion 17 may be disposed at a position where stress is generated by vibration of the beam portion 12. The piezoelectric portion 17 may be provided on a surface of the beam portion 12 on the vibration direction side. The multiple piezoelectric portions 17 may be provided so as to be aligned along the direction in which the beam portion 12 extends. The multiple piezoelectric portions 17 may be provided on both surfaces of the beam portion 12 in the vibration direction. In other words, the multiple piezoelectric portions 17 may be provided on the upper and lower surfaces of the beam portion 12 in the z-axis direction.

[0029] The piezoelectric section 17 includes an insulating film, a first electrode, a piezoelectric film, and a second electrode, which are stacked in this order from the beam section 12 side. When the beam section 12 deforms due to vibration, the piezoelectric section 17 deforms together with the beam section 12. As a result, when the beam section 12 vibrates, stress is applied to the piezoelectric film in the piezoelectric section 17, and this stress is converted into electric power by the piezoelectric effect of the piezoelectric film. The electric power generated by the piezoelectric film is output to the outside of the vibration power generation device 10 via the first electrode and the second electrode.

[0030] The fixing portion 13 fixes each of the beam portions 12 by an arbitrary method. The fixing portion 13 is preferably formed of a member having 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.

[0031] The housing 14 may house the weight portion 11 and the beam portion 12. The housing 14 may support the fixed portion 13.

[0032] FIG. 6 is a perspective view showing the configuration of the weight 11 and the beams 12 of a vibration power generation device 110 of a comparative example having a conventional structure. Each of the beams 12 of the vibration power generation device 110 extends in different directions from the center of the weight 11. Specifically, four beams 12 extend in four directions from the weight 11. In vibration power generation, it is known that the amount of power generated increases when the weight of the weight is increased. However, in the case of a conventional structure such as the vibration power generation device 110 of the comparative example, for example, the center of gravity G is close to only some of the beams 12, and a slight deviation of the center of gravity G is likely to occur. If the center of gravity G is shifted, a force that tries to rotate the beams 12 is generated during vibration. If the weight of the weight 11 is increased to increase the amount of power generated, the force that tries to rotate the beams 12 increases, and a torsion mode that vibrates while twisting, as well as in the z-axis direction, is likely to occur. In addition, if the natural frequency of the torsion mode is close to the natural frequency of the primary mode that vibrates in the z-axis direction, which is normal operation, the amount of power generated decreases. As the weight of the weight portion 11 is increased, the natural frequency of the torsion mode tends to approach the natural frequency of the primary mode, and the influence of the decrease in the amount of power generation becomes greater. Thus, in the vibration power generation device 110 of the comparative example, there is a limit to increasing the amount of power generation by increasing the weight of the weight.

[0033] In contrast, in the vibration power generation device 10, the beams 12 are located on the same plane as described above, and are located so as to surround the center of gravity G of the weight 11. Therefore, the torsion mode is unlikely to occur. Here, the weights of the weights 11 until the amount of power generation decreases due to the torsion mode were compared between the vibration power generation device 110 of the comparative example and the vibration power generation device 10 of the present embodiment. The weights of the weights 11 at which the natural frequency (ft) of the torsion mode approaches the natural frequency (f1) of the primary mode, that is, (ft) / (f1)=1.2, were compared. First, the weight was 10.6 g in the vibration power generation device 110 of the comparative example. In contrast, the weight was 42.5 g in the vibration power generation device 10. As is clear from this comparison, the vibration power generation device 10 of the present embodiment is unlikely to cause the torsion mode.

[0034] As described above, the vibration power generation device 10 and the sensor module 21 according to this embodiment are configured in such a way that a torsion mode is unlikely to occur even if the weight of the weight is increased.

[0035] 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.

[0036] In the above embodiment, the vibration power generation device 10 has four beams 12. The connection parts 19 are located at the vertices of a square. However, the vibration power generation device 10 is not limited in number and shape as long as the beams 12 are located to surround the center of gravity G of the weight 11. FIG. 5 is a top view showing another configuration of the weight 11 and the beams 12 of the vibration power generation device 10. As shown in FIG. 5, the number of the beams 12 may be three, and the connection parts 19 may be located at the vertices of an equilateral triangle. As another example, the number of the beams 12 may be five, and the connection parts 19 may be located at the vertices of a regular pentagon. As yet another example, the number of the beams 12 may be six, and the connection parts 19 may be located at the vertices of a regular hexagon. Here, La and Lb in FIG. 5 may be different values ​​from those in FIG. 4. That is, La is a symbol for indicating that the distances between the center of gravity G and the connection parts 19 are equal. Furthermore, Lb is a symbol indicating that the lengths of the beam portions 12 are equal. For ease of viewing, the fixed portion 13, the housing 14, and the piezoelectric portion 17 shown in FIG. 2 are shown in transparent form in FIG. 5 and FIG. 6.

[0037] 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, for example, the strength of vibration together with the power generated by the piezoelectric film in the piezoelectric portion 17. The controller 24 may calculate the speed of the 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]

[0038] 10. Power-generating vibration device 11 Weight 12 Beam section 13 Fixed part 14. Chassis 15 Main body 16 Neck 17 Piezoelectric section 19 Connection 21 Sensor Module 22 Sensors 23 Communications Department 24 Controller 110 Power-generating vibration device

Claims

1. A weight portion and a plurality of beam portions each having a connection portion connected to the weight portion, the plurality of beam portions are each located on the same plane and are located so as to surround the center of gravity of the weight portion, A vibration power generation device, wherein the distances between the center of gravity of the weight portion and the connection portion are all equal.

2. The vibration power generation device according to claim 1 , wherein the connection portions are positioned to become vertices of a regular polygon.

3. The vibration power generation device according to claim 2 , wherein the beam portions have the same length.

4. The number of the beam portions is three, The vibration power generation device according to claim 3 , wherein the connection portions are located at vertices of an equilateral triangle.

5. The number of the beam portions is four, The vibration power generation device according to claim 3 , wherein the connection portions are located at vertices of a square.

6. The number of the beam portions is five, The vibration power generation device according to claim 3 , wherein the connection portions are located at vertices of a regular pentagon.

7. The number of the beam portions is six, The vibration power generation device according to claim 3 , wherein the connection portions are located at vertices of a regular hexagon.

8. A weight portion and a plurality of beam portions each having a connection portion connected to the weight portion, the plurality of beam portions are each located on the same plane and are located so as to surround the center of gravity of the weight portion, A sensor module, wherein distances between the center of gravity of the weight portion and the connection portion are equal.

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