JP6647498B2 - Power generation element - Google Patents

Description

  The present invention relates to a power generating element that generates electric power by converting mechanical vibration energy into electric energy.

  Conventionally, as shown in FIG. 14A, a plate-shaped structure 10 having flexibility, a piezoelectric element 12 that generates electric charges based on deformation of the plate-shaped structure 10, and a plate-shaped structure 10 There was a power generating element 18 composed of a pedestal 14 supporting a base end in a cantilever structure and a weight body 16 provided at a distal end of the plate-shaped structure 10. The power generating element 18 is used when the pedestal 14 is attached to some vibration source 20 and defines an XYZ three-dimensional coordinate system. When the XYZ three-dimensional coordinate system is defined, the plate-like structure 10 is configured such that its plate surface is a surface parallel to the XY plane. Be placed.

  For example, as shown in FIG. 14B, the piezoelectric element 12 includes a lower electrode layer G covering the entire upper surface of the plate-shaped structure 10, a piezoelectric material layer P covering the entire upper surface of the lower electrode layer G, and a piezoelectric material layer P. The upper electrode layer E is provided in a specific region on the upper surface, and the region where the upper electrode layer E is provided substantially operates as the piezoelectric element 12.

  When vibration in the Z-axis direction is applied to the pedestal 14, the vibration acts on the weight body 16 and the plate-like structure 10, as shown in FIG. The flexure causes the electric charge to be generated in the piezoelectric element 12 based on the deformation. Then, the charge generated in the piezoelectric element 12 is taken out as electric power by a rectifying and smoothing circuit (not shown) connected to the piezoelectric element 12.

  The power generation element 18 has one resonance system (resonance frequency frz) based on the flexibility of the plate-shaped structure 10, and as shown in FIG. 15B, the frequency fz of the applied vibration is changed to the resonance frequency frz. , The amplitude A of the plate-like structure 10 increases in resonance with this vibration. Therefore, when the resonance frequency frz is set near the frequency fz of the applied vibration and the Q value of the resonance is increased to increase the peak value of the amplitude A, the power generation amount of the power generation element 18 can be increased.

  The resonance frequency frz can be set by adjusting the spring constant in the Z-axis direction of the plate-shaped structure 10 and the mass of the weight body 16. For example, the spring constant can be increased or the weight body can be increased. Reducing the mass of 16 makes it possible to increase the resonance frequency frz. The Q value of the resonance can be increased by minimizing the component that attenuates the vibration (for example, by making a vacuum state).

  Patent Document 1 discloses a piezoelectric power generation device having one resonance system, similarly to the power generation element 18 described above.

WO2012 / 105368

  The conventional power generation element 18 and the piezoelectric power generation device of Patent Document 1 can increase the power generation amount by increasing the Q value of the resonance system. However, since there is a physical limit, the frequency of the applied vibration fz is limited. Even if the resonance frequencies frz were accurately matched, the power generation efficiency was low.

  The present invention has been made in view of the background art described above, and has as its object to provide a power generation element having a simple structure that can significantly increase the amount of power generation as compared with the related art.

  The present invention provides a first and a second plate-like structure having a flexible portion, a pedestal supporting the first plate-like structure, and a first and a second plate-like structure in the first and the second plate-like structures. A piezoelectric element that generates an electric charge based on deformation of at least one of the flexible portions. When the XYZ three-dimensional coordinate system is defined, the first and second plate-like structures have an XY plane. The first plate-shaped structure is connected directly or indirectly to the pedestal at its base end, and the second plate-shaped structure is A base end is connected to a distal end of the first plate-like structure via a connector, and a spring constant of a flexible portion of the first plate-like structure, and a spring constant of the first plate-like structure. A first resonance system is formed by the mass of the object connected to the tip, and a spring constant of a flexible portion of the second plate-like structure and the second plate-like structure A second resonance system is formed by the mass of the object connected to the tip, and the spring constant of the flexible portion of the second plate-like structure is determined by the spring constant of the flexible portion of the first plate-like structure. The frequency element having a half-width of the second resonance system, which is different from the constant, is a power generating element in which all or a part of the frequency band overlaps with the half-width frequency band of the first resonance system. The spring constant of the flexible portion of the second plate-like structure is smaller than the spring constant of the flexible portion of the first plate-like structure. Alternatively, the flexible portion of the second plate-like structure differs from the flexible portion of the first plate-like structure in at least one of a length, a width, and a thickness in a bending direction. Is

  Further, the present invention provides n plate-like structures having a flexible portion (n is a natural number of 3 or more) and a first plate-like structure which is one of the n plate-like structures. A pedestal for supporting a body, and a piezoelectric element that generates an electric charge based on deformation of the flexible portion of the n plate-shaped structures or at least deformation of the flexible portion of the n-th plate structure. , XYZ three-dimensional coordinate system is defined, the n plate-like structures are arranged such that their plate surfaces are parallel to the XY plane, and the first plate-like structure is The base end is directly or indirectly connected to the pedestal, and the ka-th plate-like structure (ka is an even number, 2 ≦ ka ≦ n) among the n plate-like structures is a base end of itself. The part is connected to the tip of the (ka-1) -th plate-like structure via a connector, and the kb-th plate-like structure (kb is an odd number, 3 ≦ k .Ltoreq.n), its base end is connected to the distal end of the (kb-1) th plate-like structure via a connector, and the spring constant of the flexible portion of the first plate-like structure is: And a mass of an object connected to the tip of the first plate-like structure forms a first resonance system, and a spring constant of a flexible portion of the ka-th plate-like structure; The ka-th resonance system is formed by the mass of the object connected to the tip of the plate-shaped structure, and the spring constant of the flexible portion of the kb-th plate-shaped structure and the kb-th plate-shaped structure The kb-th resonance system is formed by the mass of the object connected to the tip, and the spring constant of the flexible portion of the ka-th plate-like structure is the same as that of the (ka-1) -th plate-like structure. Unlike the spring constant of the flexible portion, the spring constant of the flexible portion of the kb-th plate-like structure is equal to the spring constant of the flexible portion of the (kb-1) -th plate-like structure. The frequency band of the half-width of each resonance system of the n plate-like structures is entirely or partially overlapped with the frequency band of the half-width of the resonance system of the other plate-like structures. Power generating element. The spring constant of the flexible portion of the ka-th plate-like structure is smaller than the spring constant of the flexible portion of the (ka-1) -th plate-like structure. The spring constant of the portion is smaller than the spring constant of the flexible portion of the (kb-1) -th plate-shaped structure. Alternatively, the ka-th plate-shaped structure differs from the (ka-1) -th plate-shaped structure in at least one of a length, a width, and a thickness in a bending direction. The plate-shaped structure is different from the (kb-1) -th plate-shaped structure in at least one of length, thickness, and width.

  Further, the present invention provides n plate-like structures having a flexible portion (n is a natural number of 3 or more) and a first plate-like structure which is one of the n plate-like structures. A base for supporting the body, and a charge based on the deformation of the flexible portion of the n plate-like structures or the deformation of the flexible portion of the plate-like structure of the second to n-th plate structures. When the XYZ three-dimensional coordinate system is defined, the n plate-like structures are arranged such that their plate surfaces are parallel to the XY plane, and the first plate The plate-shaped structure has its own base end directly or indirectly connected to the pedestal. The plate-shaped structure other than the first plate-shaped structure has its base end connected to the first plate. Each of which is connected to a distal end of the plate-like structure via a connector, and a spring constant of a flexible portion of the first plate-like structure, and an object connected to the distal end of the first plate-like structure. The first resonance system is formed by the quantity, and the spring constant of the flexible portion of the plate-shaped structure other than the first plate-shaped structure, and the mass of the object connected to the tip of the plate-shaped structure In addition, a resonance system other than the first resonance system is formed, and a spring constant of a flexible portion of the plate-shaped structure other than the first plate-shaped structure is set to be equal to that of the first plate-shaped structure. The power factor is different from the spring constant of the bending portion, and the whole or a part of the frequency band of the half width of the first resonance system overlaps with the frequency band of the half width of the other resonance system. . The spring constant of the flexible portion of the plate-shaped structure other than the first plate-shaped structure is smaller than the spring constant of the flexible portion of the first plate-shaped structure. Alternatively, the flexible portion of each of the plate-like structures other than the first plate-like structure has a length, a width, and a thickness in a bending direction that are different from those of the first plate-like structure. At least one of them is different.

In each of the power generating elements, a weight body is provided at the end of the specific plate-shaped structure.

  Since the power generating element of the present invention has two or more resonance systems connected to each other and is set so that the frequency bands having the half-value widths of the respective resonance characteristics overlap each other, the interaction between the resonance systems causes Q of the typical resonance can be made very high. Therefore, it is possible to significantly increase the amount of power generation compared to the related art with respect to the vibration in the frequency band where the half widths of each other overlap. In addition, since the structure is simple, it can be easily manufactured using a general manufacturing process.

FIG. 3A is a perspective view illustrating an appearance of a first embodiment of the power generating element of the present invention, and FIG. 4B is a front view illustrating an operation when vibration in a Z-axis direction is applied. 5A is a graph illustrating resonance characteristics in the Z-axis direction of first and second resonance systems included in the power generating element of the first embodiment, and FIG. 5B is a graph illustrating power generation. It is a perspective view (a) showing an appearance of a modification of the power generating element of the first embodiment, and a front view (b) showing an operation when vibration in the Z-axis direction is applied. It is a perspective view (a) showing an appearance of another modification of the power generating element of the first embodiment, and a front view (b) showing an operation when vibration in the Z-axis direction is applied. 5A is a graph illustrating an example of resonance characteristics of the first to third resonance systems of the power generating element illustrated in FIG. 4 in the Z-axis direction, and FIG. 5B is a graph illustrating power generation. It is the perspective view (a), the top view (b), and the front view (c) which show the external appearance of the 2nd embodiment of the electric power generation element of this invention. It is the front view (a) and rear view (b) which show the operation | movement when the vibration of a Z-axis direction is applied to the power generation element of 2nd embodiment. 7A is a graph illustrating an example of resonance characteristics of the first to third resonance systems of the power generating element according to the second embodiment in the Z-axis direction, and FIG. 6B is a graph illustrating power generation. It is the perspective view (a), the top view (b), and the right side view (c) which show the external appearance of one modification of the power generation element of 2nd embodiment. It is the top view (a) which shows the external appearance of 3rd Embodiment of the power generation element of this invention, the partial cross section (b) seen from the front, and the bottom view (c). FIG. 9A is a plan view illustrating an appearance of a modification of the power generating element according to the third embodiment, and FIG. 9B is a view illustrating the polarity of output of each piezoelectric element with respect to applied vibration. 12A is a graph showing resonance characteristics of first and second resonance systems included in the power generation element shown in FIG. 11A, a graph in the Z-axis direction (a), a graph in the X-axis direction (b), and a Y-axis direction. (C) of FIG. FIG. 14A is a plan view illustrating the appearance of another modification of the power generating element according to the third embodiment, and FIG. 14B is a view illustrating the polarity of the output of each piezoelectric element with respect to applied vibration. It is a perspective view (a) showing the appearance of a conventional power generating element, and a front view (b) showing the structure of a piezoelectric element. FIG. 14A is a front view illustrating an operation when vibration in the Z-axis direction is applied to the power generating element of FIG. 14, and FIG. 14B is a graph (b) illustrating a resonance characteristic and a power generation amount of the resonance system of the power generating element in the Z axis direction. is there.

  Hereinafter, a first embodiment of a power generating element of the present invention will be described with reference to FIGS. As shown in FIG. 1A, the power generating element 22 according to this embodiment has a first plate-like structure 24 having a flexible portion and a deformable portion of the first plate-like structure 24. A first piezoelectric element that generates electric charges based on the first piezoelectric element, a second plate-like structure having a flexible portion, and electric charges based on deformation of the flexible portion of the second plate-like structure And a pedestal 32 for supporting the first plate-shaped structure 24 in a cantilever structure. When the power generating element 22 is used with the pedestal 14 attached to some vibration source 20 and defines an XYZ three-dimensional coordinate system, each of the plate-like structures 24 and 28 has a plate surface on a surface parallel to the XY plane. It is arranged so that it becomes.

  The first plate-shaped structure 24 extends in a direction parallel to the Y axis so that the base end is directly connected to the pedestal 32 and the direction from the base end to the front end is the positive direction of the Y axis. ing. The second plate-shaped structure 28 is located above the first plate-shaped structure 24, and has a base end connected to a distal end of the first plate-shaped structure 24 via a connector 34. It extends in a direction parallel to the Y axis so that the direction from the end to the tip is the Y axis negative direction. In addition, a weight body 36 is provided at the tip of the second plate-shaped structure 28.

  The first and second piezoelectric elements 26 and 30 are each composed of a lower electrode layer G, a piezoelectric material layer P, and an upper electrode layer E, similarly to the piezoelectric element 12 shown in FIG.

  With the above structure, two resonance systems Re1 and Re2 are formed in the power generation element 22. The first resonance system Re1 is a resonance system formed based on the flexibility of the first plate-like structure 24, and the resonance frequency frz1 in the Z-axis direction is higher than that of the first plate-like structure 24. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the tip of the first plate-like structure 24 (the mass of the connector 34, the second plate-like structure 28, and the weight 36) And is set by adjusting

  The second resonance system Re2 is a resonance system formed based on the flexibility of the second plate-like structure 28, and the resonance frequency frz2 in the Z-axis direction is higher than that of the second plate-like structure 28. It is set by adjusting the spring constant of the flexible portion in the Z-axis direction and the mass of the object (the mass of the weight body 36) connected to the tip of the second plate-shaped structure 28.

  The resonance characteristics of the two resonance systems Re1 and Re2 are represented as shown in FIG. Note that the resonance characteristics of the second resonance system Re2 shown in FIG. 2A assume that the base end of the second plate-like structure 28 is directly connected to the pedestal 32, The interaction with the resonance system Re1 is not included.

  The resonance characteristic of the first resonance system Re1 is that, near the resonance frequency frz1, peaking in which the amplitude A1 increases in resonance with the applied vibration occurs, and in a frequency band of a half width hz1 centered on the resonance frequency frz1, The amplitude A1 is half or more of the peak value. In the resonance characteristic of the second resonance system Re2, peaking in which the amplitude A2 increases in resonance with the applied vibration occurs near the resonance frequency frz2, and in a frequency band of a half width hz2 centered on the resonance frequency frz2, The amplitude A2 is half or more of the peak value. What is characteristic here is that a part of the frequency band of the half width hz1 of the first resonance system Re1 and a part of the frequency band of the half width hz2 of the second resonance system Re2 overlap each other.

  Next, an operation when vibration in the Z-axis direction is applied to the power generation element 22 will be described. Here, in order to simplify the explanation, the Q values of the first and second resonance systems Re1 and Re2 are respectively Qz1 (>> 1) and Qz2 (>> 1), and Qz1 and QZ2 are equal to each other. Assuming that the frequencies frz1 and frz2 match each other, consider a case in which vibration having the same frequency as the resonance frequencies frz1 and frz2 is applied to the power generation element 22.

  When vibration is applied to the pedestal 32, this vibration is transmitted to the first resonance system Re1, and as shown in FIG. 1B, the flexible portion of the first plate-shaped structure 24 bends in the thickness direction, An acceleration (Qz1 · α) that is Qz1 times the acceleration α at which the pedestal 32 is displaced is generated at the distal end of the first plate-shaped structure 24. Therefore, in the first piezoelectric element 26, an electric charge corresponding to the difference (Qz1 · α) between the acceleration of the distal end portion and the acceleration of the proximal end portion is generated. For example, if Qz1 = 10, a charge corresponding to the acceleration (10α) will be generated.

  Further, the vibration of the tip portion of the first plate-shaped structure 24 is transmitted to the second resonance system Re2, and the flexible portion of the second plate-shaped structure 28 is turned in the opposite direction to the first plate-shaped structure 24. Bend. Then, an acceleration (Qz2 · Qz1 · α) that is Qz2 times the acceleration at which the tip of the first plate-shaped structure 24 is displaced is generated at the tip of the second plate-shaped structure 28. Therefore, in the second piezoelectric element 30, an electric charge corresponding to a difference (Qz2 · Qz1 · α) between the acceleration of the distal end portion and the acceleration of the proximal end portion is approximately generated. For example, if Qz2 = Qz1 = 10, a charge corresponding to the acceleration (100α) will be generated.

  As described above, the power generation element 22 can obtain a charge corresponding to (Qz1 · α) in the first resonance system Re1, and a charge corresponding to (Qz2 · Qz1 · α) in the second resonance system Re2. And the sum of these is taken out as power.

  Assuming that Qz2 = Qz1 >> 1, more charges are generated in the second resonance system Re2 than in the first resonance system Re1, so that the second resonance system Re2 generates much more electric power. (The same applies to Qz2 ≠ Qz1). For example, in the case of the conventional power generation element 18 described above, since there is only one resonance system, only the same power generation as the first resonance system Re1 of the power generation element 22 can be performed. On the other hand, the power generation element 22 can generate much more power than the conventional power generation element 18 by the function of the second resonance system Re2.

  The same operation is performed when the weight body 36 of the power generating element 22 is provided on the upper surface side of the second plate-shaped structure 28 instead of the lower surface side. Further, if the power generation amount of the first resonance system Re1 is negligibly smaller than the power generation amount of the second resonance system Re2, the first piezoelectric element 26 may be omitted, and a power generation amount equal to or more than a certain value is secured. In addition, the manufacturing process can be simplified.

  Until now, it has been assumed that the resonance frequencies frz1 and frz2 coincide with each other, and the operation when the vibration having the same frequency as the resonance frequencies frz1 and frz2 is applied to the power generation element 22 has been described. However, at the time of mass production, manufacturing variations and the like occur, so that it is difficult to accurately match the resonance frequencies frz1 and frz2. Thus, as a result of an experiment or a simulation performed by the inventor, a part of the frequency band having the half width hz1 of the first resonance system Re1 and a part of the frequency band having the half width hz2 of the second resonance system Re2 are different. As shown in FIG. 2 (b), it was found that a sufficiently high power generation amount could be obtained in the overlapping frequency band if they overlapped each other.

  As described above, the power generation element 22 has the two resonance systems Re1 and Re2 connected to each other, and is set so that the frequency bands of the half-value widths hz1 and hz2 of the respective resonance characteristics overlap each other. Due to the interaction between the systems, the overall resonance Q is very high. Therefore, it is possible to significantly increase the amount of power generation with respect to the vibration in the frequency band where the half widths hz1 and hz2 overlap each other. In addition, since the structure is simple, it can be easily manufactured using a general manufacturing process.

  Next, two modified examples of the power generation element 22 of the first embodiment will be described. Here, the same components as those of the power generation element 22 are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in FIGS. 3A and 3B, the power generating element 38 of the first modified example has the same components as the power generating element 22 except for the second plate-like structure 28. Is disposed below the first plate-shaped structure 24. Accordingly, the second piezoelectric element 30 is provided on the lower surface side of the second plate-shaped structure 28, and the connecting body 34 is The weight body 36 is provided on the lower surface side of the distal end of the first plate-shaped structure 24, and the weight body 36 is provided on the upper surface side of the second plate-shaped structure 28.

  In the power generation element 38, the arrangement of the first and second resonance systems Re1 and Re2 in the vertical direction is opposite to that of the power generation element 22, but the resonance characteristics of each resonance system are the same as the graph shown in FIG. The power generation performance is also the same as the graph shown in FIG. Therefore, also in the power generating element 38, the same excellent effects as those of the power generating element 22 can be obtained. The same operation is performed when the weight body 36 of the power generating element 38 is provided on the upper surface side of the second plate-shaped structure 28 instead of the lower surface side.

  As shown in FIGS. 4A and 4B, the power generating element 40 according to the second modified example has a configuration in which the weight body 36 is deleted from the configuration of the power generating element 22, and a third plate-shaped structure is newly added. 42, a third piezoelectric element 44, a connecting body 46, and a weight 48 are added.

  The third plate-like structure 42 is located above the second plate-like structure 28, and has a base end connected to a distal end of the second plate-like structure 28 via a connector 46. It extends in a direction parallel to the Y axis so that the direction from the end to the tip is the positive direction of the Y axis. A weight 48 is provided at the tip of the third plate-like structure 42. Other configurations are the same as those of the power generation element 22.

  With the above structure, three resonance systems Re1, Re2, and Re3 are formed in the power generation element 40. The first resonance system Re1 is a resonance system formed based on the flexibility of the first plate-like structure 24, and the resonance frequency frz1 in the Z-axis direction is higher than that of the first plate-like structure 24. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the distal end of the first plate-shaped structure 24 (connecting body 34, second plate-shaped structure 28, connecting body 46, third body (The mass of the plate-like structure 42 and the weight body 48).

  The second resonance system Re2 is a resonance system formed based on the flexibility of the second plate-like structure 28, and the resonance frequency frz2 in the Z-axis direction is higher than that of the second plate-like structure 28. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the tip of the second plate-like structure 28 (the mass of the connector 46, the third plate-like structure 42, and the weight 48) And is set by adjusting

  The third resonance system Re3 is a resonance system formed based on the flexibility of the third plate-like structure 42. The resonance frequency frz3 in the Z-axis direction is higher than that of the third plate-like structure 42. It is set by adjusting the spring constant of the bending portion in the Z-axis direction and the mass of the object (the mass of the weight 48) connected to the distal end of the third plate-shaped structure 42. The weight body 48 is a member for adjusting resonance characteristics, and is formed by another method (for example, a method of adjusting the spring constant by changing the Young's modulus or the shape of the three plate-like structures 24, 28, 42). If the resonance characteristic can be adjusted, it can be omitted.

  The resonance characteristics of the three resonance systems Re1, Re2, Re3 are set, for example, as shown in FIG. The resonance characteristics of the second resonance system Re2 shown in FIG. 5A assume a state in which the base end of the second plate-like structure 28 is directly connected to the pedestal 32. Does not include interaction with the system. Similarly, the resonance characteristics of the third resonance system Re3 are based on the assumption that the base end of the third plate-like structure 42 is directly connected to the pedestal 32, and the interaction with the other resonance system is Not included.

  Characteristically, a part of the frequency band of the half width hz1 of the first resonance system Re1 overlaps a part of the frequency band of the half width hz3 of the third resonance system Re3, and the half width hz1 of the second resonance system Re2. The point is that a part of the frequency band of the third resonance system Re3 also overlaps a part of the frequency band of the half width hz3 of the third resonance system Re3. Here, the frequency bands of the half widths hz2 and hz3 do not overlap.

  Since the power generation element 40 has the resonance characteristics of each resonance system set as shown in FIG. 5A, as shown in FIG. Can be obtained at It is also possible to set the frequency bands of the half-value widths hz1 and hz2 to overlap. In this case, the frequency band where the power generation amount shows a peak becomes one, and the peak value of the power generation amount becomes higher.

  Next, a second embodiment of the power generating element of the present invention will be described with reference to FIGS. As shown in FIG. 6A, the power generating element 50 according to this embodiment includes a first plate-like structure 52 having a flexible portion and a deformation of the flexible portion of the first plate-like structure 52. A first piezoelectric element that generates electric charges based on the first piezoelectric element, a second plate-like structure having a flexible portion, and electric charges based on deformation of the flexible portion of the second plate-like structure A second piezoelectric element 58, a third plate-like structure 60 having a flexible portion, and a third piezoelectric member that generates electric charges based on the deformation of the flexible portion of the third plate-like structure 60. And an element 62. Further, a pedestal 64 for supporting the first plate-shaped structure 52 in a cantilever structure is provided. When the power generating element 50 is used with the pedestal 64 attached to some vibration source 20 and defines an XYZ three-dimensional coordinate system, each of the plate-like structures 52, 56, and 60 has a plate surface parallel to the XY plane. It is arranged so that it may become a surface.

  The first plate-like structure 52 has a base end directly connected to the pedestal 64 and extends in a direction parallel to the Y axis so that the direction from the base end to the front end is the positive direction of the Y axis. ing. The second and third plate-like structures 56 and 60 are arranged on the side of the first plate-like structure 52 so as to sandwich the first plate-like structure 52 therebetween, and the respective base ends thereof It is connected to the distal end of the first plate-like structure 52 via a connector 66, and extends in a direction parallel to the Y axis so that the direction from the proximal end to the distal end is the Y axis negative direction. . In addition, a weight body 68 is provided on the lower surface side of the connecting body 66, a weight body 70 is provided on the lower surface side of the distal end of the second plate-like structure 56, and the distal end of the third plate-like structure 60 is provided. The weight body 72 is provided on the lower surface side of the portion.

  Therefore, when the vibration in the Z-axis direction is applied to the pedestal 64 and the first plate-like structure 52 is bent in the thickness direction, the second plate-like structure 56 becomes the first plate-like structure 56 as shown in FIG. Of the plate-like structure 52 in the opposite direction. Similarly, when the first plate-like structure 52 bends in the thickness direction, the third plate-like structure 60 bends in the opposite direction to the first plate-like structure 52 as shown in FIG. No.

  The first, second, and third piezoelectric elements 54, 58, and 62 are each composed of a lower electrode layer G, a piezoelectric material layer P, and an upper electrode layer E, similarly to the piezoelectric element 12 shown in FIG. ing.

  With the above structure, three resonance systems Re1, Re2, and Re3 are formed in the power generation element 50. The first resonance system Re1 is a resonance system formed based on the flexibility of the first plate-like structure 52, and the resonance frequency frz1 in the Z-axis direction is higher than that of the first plate-like structure 52. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the distal end of the first plate-like structure 52 (connector 66, second and third plate-like structures 56 and 60, and weight (Mass of weights 68, 70, 72).

  The second resonance system Re2 is a resonance system formed based on the flexibility of the second plate-like structure 56. The resonance frequency frz2 in the Z-axis direction is higher than that of the second plate-like structure 56. It is set by adjusting the spring constant in the Z-axis direction of the flexible portion and the mass of the object (the mass of the weight body 70) connected to the distal end of the second plate-shaped structure 28.

  The third resonance system Re3 is a resonance system formed based on the flexibility of the third plate-like structure 60, and the resonance frequency frz3 in the Z-axis direction is higher than that of the third plate-like structure 60. It is set by adjusting the spring constant of the flexible portion in the Z-axis direction and the mass of the object (the mass of the weight 72) connected to the distal end of the third plate-shaped structure 60.

  The resonance characteristics of the three resonance systems Re1, Re2, Re3 are set, for example, as shown in FIG. Characteristically, a part of the frequency band of the half width hz2 of the second resonance system Re2 overlaps with a part of the frequency band of the half width hz1 of the first resonance system Re1, and the half width hz3 of the third resonance system Re3. Is also overlapped with a part of the frequency band having the half width hz1 of the first resonance system Re1. Here, the frequency bands of the half widths hz2 and hz3 do not overlap.

  In the power generation element 50, since the resonance characteristics of each resonance system are set as shown in FIG. 8A, a large amount of power generation can be obtained in two frequency bands as shown in FIG. 8B. . It is also possible to set the frequency bands of the half widths hz1 and hz2 to overlap. In this case, the frequency band where the power generation amount shows a peak becomes one, but the peak value of the power generation amount becomes higher.

  Although the power generation element 40 (FIG. 4) described above also has three resonance systems, in the case of the power generation element 40, since the three resonance systems are sequentially arranged in series, they are directly connected. Interaction also occurs between the two resonance systems Re1 and Re3. On the other hand, in the power generating element 50, although the first and second resonance systems Re1 and Re2 are in series and the first and third resonance systems Re1 and Re2 are in series, the second and third resonance systems System Re2, Re3 are not in series. Therefore, almost no interaction occurs between the two resonance systems Re2 and Re3 that are not directly connected. Therefore, the power generating element 50 performs substantially the same operation as using two power generating elements 22 (FIG. 1) in parallel.

  The power generation element 50 can obtain more power generation than the power generation element 22. Further, in the case of the power generating element 22, the plate-like structures 24, 28 are arranged so as to overlap vertically, so that they are easily in contact with each other. Since the plate-like structures 52, 56, and 60 do not collide with each other, the maximum amount of deflection of the plate-like structures 52, 56, and 60 can be increased, and the amount of power generation can be further increased. it can.

  Next, a power generation element 74 which is a modification of the power generation element 50 of the second embodiment will be described with reference to FIG. Here, the same components as those of the power generating element 50 are denoted by the same reference numerals, and description thereof will be omitted. The power generating element 74 has a configuration in which the weights 70 and 72 are removed from the configuration of the power generating element 50, and a U-shaped weight 76 is newly provided. Other configurations are the same as those of the power generation element 50.

  The weight body 76 has such a shape that the distal ends of the weight bodies 70 and 72 are connected to each other by a cross beam and integrated. Therefore, each end of the plate-like structures 56 and 60 is connected via the weight body 76, and the two plate-like structures 56 and 60 cooperate to form the second plate-like structure ( (A single plate-like structure). Hereinafter, a combination of the characteristics of the two plate-like structures 56 and 60 will be described as a second plate-like structure 56x.

  With the above structure, two resonance systems Re1 and Re2 are formed in the power generating element 74. The first resonance system Re1 is a resonance system formed based on the flexibility of the first plate-like structure 52, and the resonance frequency frz1 in the Z-axis direction is higher than that of the first plate-like structure 52. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the distal end of the first plate-like structure 52 (connector 66, weight 68, second plate-like structure 56x and weight) (The mass of the body 76).

  The second resonance system Re2 is a resonance system formed based on the flexibility of the second plate-like structure 56x, and the resonance frequency frz2 in the Z-axis direction is higher than the resonance frequency frz2 of the second plate-like structure 56x. It is set by adjusting the spring constant in the Z-axis direction of the flexible portion and the mass (mass of the weight body 76) of the object connected to the tip of the second plate-shaped structure 56x.

  The resonance characteristic of each resonance system is the same as the graph of the power generation element 22 shown in FIG. Therefore, the power generating element 74 also performs the same operation as the power generating element 22 and can obtain the same effect as the power generating element 50.

  Next, a third embodiment of the power generating element of the present invention will be described with reference to FIG. The power generation element 78 of this embodiment includes a first plate-shaped structure 80 having a flexible portion, and a first piezoelectric element that generates electric charges based on deformation of the flexible portion of the first plate-shaped structure 80. An element 82, a second plate-like structure 84 having a flexible portion, a second piezoelectric element 86 that generates electric charges based on deformation of the flexible portion of the second plate-like structure 84, A pedestal 88 for supporting the one plate-like structure 80 in a cantilever structure is provided. When the power generating element 78 is used with the pedestal 88 attached to some vibration source 20 and defines an XYZ three-dimensional coordinate system, each of the plate-like structures 80 and 84 has a plate surface parallel to the XY plane. It is arranged so that it becomes.

  The pedestal 88 is formed in the shape of a quadrangular prism, and is provided so as to surround other members. The first plate-shaped structure 80 has a base end directly connected to the inner wall of the pedestal 88 and a direction parallel to the Y axis so that the direction from the base end to the front end is the positive direction of the Y axis. Is growing. At the tip end of the first plate-shaped structure 80, a connector 90 formed in the shape of a rectangular frame plate is extended in the Y-axis positive direction.

  The second plate-shaped structure 84 is located inside the connection body 90, and has a base end located at an inner edge of the connection body 90 (an inner edge of one side facing the portion to which the first plate-shaped structure 80 is connected). )It is connected to the. In other words, the second plate-like structure 84 is connected to the first plate-like structure 80 via the connector 90, and the Y-axis negative direction is set so that the direction from the base end to the distal end is the Y-axis negative direction. It extends in a direction parallel to the axis. In addition, a weight 92 formed in the shape of a rectangular tube having the same size as the connecting body 90 is provided on the lower surface side of the connecting body 90, and the weight is formed on the lower surface side of the distal end of the second plate-like structure 84. A weight body 94 is provided so as to be surrounded by the weight body 92. Therefore, when vibration in the Z-axis direction is applied to the pedestal 88 and the first plate-like structure 80 is bent in the thickness direction, the second plate-like structure 84 is oriented in the opposite direction to the first plate-like structure 80. To bend.

  The first and second piezoelectric elements 82 and 86 are each composed of a lower electrode layer G, a piezoelectric material layer P, and an upper electrode layer E, similarly to the piezoelectric element 12 shown in FIG.

  With the above structure, two resonance systems Re1 and Re2 are formed in the power generation element 78. The first resonance system Re1 is a resonance system formed based on the flexibility of the first plate-shaped structure 80, and the resonance frequency frz1 in the Z-axis direction is higher than that of the first plate-shaped structure 80. The spring constant of the flexible portion in the Z-axis direction and the mass of the object connected to the distal end of the first plate-like structure 80 (connector 90, weight 92, second plate-like structure 84 and weight) Of the body 94).

  The second resonance system Re2 is a resonance system formed based on the flexibility of the second plate-like structure 84, and the resonance frequency frz2 in the Z-axis direction is higher than that of the second plate-like structure 84. It is set by adjusting the spring constant of the flexible portion in the Z-axis direction and the mass of the object (the mass of the weight body 94) connected to the distal end of the second plate-shaped structure 84.

  The resonance characteristic of each resonance system is the same as the graph of the power generation element 22 shown in FIG. 2A, and the same effect as the power generation element 22 can be obtained in the power generation element 78. Furthermore, in the power generating element 78, the pedestal 88 functions as a stopper for preventing the weight body 92 from being excessively displaced, and the weight body 92 has a stopper for preventing the weight body 94 from being excessively displaced. Therefore, when a strong impact is applied to the power generation element 78, the first and second plate-like structures 80 and 84 can be easily protected from being damaged. Further, since the distal end of the first plate-shaped structure 80 and the base end of the second plate-shaped structure 84 are connected to both ends (positions separated from each other) of the connecting body 90, the second A large acceleration can be applied to the resonance system Re2.

  Next, two modified examples of the power generating element 78 of the third embodiment will be described. Here, the same components as those of the power generating element 78 are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in FIG. 11A, a power generating element 96 according to a first modification replaces the first piezoelectric element 82 of the power generating element 78 with a first piezoelectric element 98 and replaces the second piezoelectric element 86 with the first piezoelectric element 98. The second piezoelectric element 100 is replaced with the second piezoelectric element 100, and the other configuration is the same as that of the power generating element 78.

  In the power generating element 78, the first piezoelectric element 82 is formed by one piezoelectric element, and the second piezoelectric element 86 is formed by one piezoelectric element. Only the vibration in the Z-axis direction is converted into electric energy. Can be converted. On the other hand, in the power generation element 96, the first piezoelectric element 98 is configured by four piezoelectric elements Ea1 to Ea4, and the second piezoelectric element 100 is configured by four piezoelectric elements Eb1 to Eb4. , XYZ can be converted into electric energy.

  The power generating element 96 has the same basic structure as the power generating element 78, and as shown in FIG. 10B, the center of gravity of the weight bodies 92, 94 is the tip of the first and second plate-like structures 80, 84. When the vibrations in the respective XY axial directions act on the weight bodies 92 and 94, a bending moment acts on the first and second plate-like structures 80 and 84. . Then, the flexible portions of the first and second plate-like structures 80 and 84 are deformed, and as shown in FIG. 11B, positive or negative charges are applied to the eight piezoelectric elements Ea1 to Ea4 and Eb1 to Eb4. Respectively occur. Therefore, not only the vibration in the Z-axis direction but also the vibration in each of the XY axes can be converted into electric energy. Note that “+” and “−” in FIG. 11B relatively represent the polarity of the charge generated in each piezoelectric element, and “+” and “−” are all interchanged. May be represented.

  The first resonance system Re1 of the power generation element 96 includes a resonance frequency frz1 and a half width hz1 in the Z-axis direction, a resonance frequency frx1 and a half width hx1 in the X-axis direction, a resonance frequency fry1 and a half width hy1 in the Y-axis direction. Have. Similarly, the second resonance system Re2 has a resonance frequency frz2 and a half width hz2 in the Z-axis direction, a resonance frequency frx2 and a half width hx2 in the X-axis direction, a resonance frequency fry2 and a half width hy2 in the Y-axis direction. are doing.

  In the Z-axis direction, as shown in FIG. 12A, a part of the frequency band having the half width hz2 is set so as to overlap a part of the frequency band having the half width hz1. Therefore, a large amount of power generation can be obtained in the overlapping frequency band due to the interaction between the two resonance systems Re1 and Re2.

  The same applies to the X-axis direction. As shown in FIG. 12B, a part of the frequency band having the half width hx2 is set so as to overlap a part of the frequency band having the half width hx1. Therefore, a large amount of power generation can be obtained in the overlapping frequency band due to the interaction between the two resonance systems Re1 and Re2.

  The same applies to the Y-axis direction. As shown in FIG. 12C, a part of the frequency band having the half width hy2 is set so as to overlap a part of the frequency band having the half width hy1. Therefore, a large amount of power generation can be obtained in the overlapping frequency band due to the interaction between the two resonance systems Re1 and Re2.

  As described above, according to the power generation element 96, all vibrations in the X, Y, and Z axial directions can be efficiently converted to electric energy, so that a larger amount of power generation can be obtained than the power generation element 78.

  As shown in FIG. 13A, a power generation element 102 according to a second modification replaces the first piezoelectric element 82 of the power generation element 78 with the first piezoelectric element 104 and replaces the second piezoelectric element 86 with the first piezoelectric element 104. It is replaced with the second piezoelectric element 106, and the other configuration is the same as that of the power generating element 78.

  In the power generating element 78, the first piezoelectric element 82 is formed by one piezoelectric element, and the second piezoelectric element 86 is formed by one piezoelectric element. Only the vibration in the Z-axis direction is converted into electric energy. Can be converted. On the other hand, in the power generating element 102, the first piezoelectric element 104 is configured by two piezoelectric elements Ea1 and Ea2, and the second piezoelectric element 106 is configured by two piezoelectric elements Eb1 and Eb2. , YZ can be converted into electric energy.

  As described above, when the vibration in the Y-axis direction acts on the weights 92 and 94 of the power generating element 102, a bending moment acts on the first and second plate-like structures 80 and 84. Then, the flexible portions of the first and second plate-like structures 80 and 84 are deformed, and as shown in FIG. 13B, four piezoelectric elements Ea1, Ea2, Eb1, and Eb2 are charged with positive or negative charges. Respectively occur. Therefore, not only the vibration in the Z-axis direction but also the vibration in the Y-axis direction can be converted into electric energy.

  The first resonance system Re1 of the power generating element 102 includes a resonance frequency frz1 and a half width hz1 in the Z-axis direction, a resonance frequency frx1 and a half width hx1 in the X-axis direction, a resonance frequency fry1 and a half width hy1 in the Y-axis direction. Have. Similarly, the second resonance system Re2 has a resonance frequency frz2 and a half width hz2 in the Z axis direction, a resonance frequency frx2 and a half width hx2 in the X axis direction, a resonance frequency fry2 and a half width hy2 in the Y axis direction. are doing. This is similar to the power generating element 96.

  In the Z-axis direction, similarly to the power generation element 96, a part of the frequency band with the half width hz2 is set to overlap with a part of the frequency band with the half width hz1 (FIG. 12A). Therefore, a large amount of power generation can be obtained in the overlapping frequency band due to the interaction between the two resonance systems Re1 and Re2.

  In the Y-axis direction, similarly to the power generation element 96, a part of the frequency band having the half-value width hy2 is set so as to overlap a part of the frequency band having the half-value width hy1 (FIG. 12C). Therefore, a large amount of power generation can be obtained in the overlapping frequency band due to the interaction between the two resonance systems Re1 and Re2.

  However, the resonance characteristics in the X-axis direction are not particularly important, and the frequency band of the half width hx2 does not have to overlap the frequency band of the half width hx1. This is because the power generating element 102 does not generate power in the X-axis direction.

  According to the power generation element 102, the vibration in the YZ biaxial directions can be efficiently converted into electric energy, so that a larger amount of power generation than the power generation element 78 can be obtained. Further, when designing the first and second resonance systems Re1 and Re2, it is necessary to consider the resonance characteristics in three directions in the case of the power generation element 96, but only in the two directions in the case of the power generation element 102. For this reason, the power generation element 102 is easier to design.

  Note that the power generating element of the present invention is not limited to the above-described embodiment and modified examples. For example, the power generating element 40 shown in FIG. 4 has a total of three resonance systems provided by connecting three plate-like structures in series, and the number of plate-like structures arranged in series and the resonance system By increasing the number more, the power generation can be increased exponentially. When the first to n-th plate-shaped structures are arranged in series, the first to n-th resonance systems are formed, and when the frequency bands of the half-value widths of the respective resonance systems overlap, the first to n-th resonance systems are furthest from the pedestal. The generated power of the n-th resonance system is maximized. Therefore, in order to increase the amount of power generation, it is important that an interaction occurs between the n-th resonance system and another resonance system. The frequency band should be set so as to overlap the frequency band of the half width of the resonance system (as many resonance systems as possible).

  The power generating element 50 shown in FIG. 6 is provided with a total of three resonance systems by connecting two other plate-like structures to the end of the first plate-like structure. By further increasing the number and the number of resonance systems, the amount of power generation can be further increased. In order to increase the amount of power generation, it is important that an interaction occurs between the first resonance system and another resonance system. The frequency band should be set so as to overlap the frequency band of the half width of the system (as many resonance systems as possible).

  The power generating element 50 shown in FIG. 6 has a configuration capable of converting only the vibration in the Z-axis direction into electric energy. If the configuration is changed to the configuration of the second piezoelectric element 98.100, all the vibrations in each of the X, Y, and Z directions can be converted into electric energy, and the amount of power generation can be further increased. Alternatively, if the first and second piezoelectric elements 82 and 86 are changed to a configuration such as the first and second piezoelectric elements 104 and 106 shown in FIG. Can be converted, and the amount of power generation can be further increased.

  In addition, the manufacturing process of the power generation element is not particularly limited, and can be freely selected in accordance with each structure. For example, in the above-described power generation elements 50, 74, 78, 96, and 102 (FIGS. 6, 9, 10, 11, and 13), a plurality of resonance systems are arranged substantially flush with each other along the XY plane. The structure can be easily manufactured by using the MEMS technology using a Si substrate, an SOI substrate, or the like. Further, the specific structure of the piezoelectric element is not limited to the structure of the piezoelectric element 18 shown in FIG. 14B, and another structure that can realize the same function may be used.

22, 38, 40, 50, 74, 78, 96, 102 Power generating elements 24, 52, 80 First plate-like structures 26, 54, 82, 98, 104 First piezoelectric elements 28, 56, 56x, 84 Second plate-shaped structure 30, 58, 86, 100, 106 Second piezoelectric element 32, 64, 88 Pedestal 34, 46, 66, 90 Connector 36, 48, 68, 70, 72, 76, 92, 94 Weights 42, 60 Third plate-like structures 44, 62 Third piezoelectric element
frx1, fry1, frz1 resonance frequency (first resonance system)
frx2, fry2, frz2 resonance frequency (second resonance system)
frz3 resonance frequency (third resonance system)
hx1, hy1, hz1 half width (first resonance system)
hx2, hy2, hz2 half width (second resonance system)
hz3 Half width (third resonance system)
Re1 First resonance system
Re2 Second resonance system
Re3 Third resonance system

Claims (9)

First and second plate-like structures having a flexible portion, a pedestal supporting the first plate-like structure, and at least one of the first and second plate-like structures. A piezoelectric element that generates an electric charge based on the deformation of the flexible portion, and a weight provided at the tip of the specific plate-shaped structure,
The first plate-shaped structure has its own base end directly or indirectly connected to the pedestal,
The second plate-shaped structure has its own base end connected to the front end of the first plate-shaped structure via a connector,
A first resonance system is formed by a flexible portion of the first plate-shaped structure and a mass of an object connected to a distal end of the first plate-shaped structure;
A second resonance system is formed by a flexible portion of the second plate-shaped structure and a mass of an object connected to a tip of the second plate-shaped structure;
The power generation element according to claim 1, wherein a half-width frequency band of the second resonance system entirely or partially overlaps a half-width frequency band of the first resonance system.   The power generating element according to claim 1, wherein a spring constant of the second plate-like structure is smaller than a spring constant of the first plate-like structure.   The flexible portion of the second plate-shaped structure differs from the flexible portion of the first plate-shaped structure in at least one of a length, a width, and a thickness in a bending direction. The power generating element according to claim 1. N plate-like structures having a flexible portion (n is a natural number of 3 or more), and a pedestal supporting a first plate-like structure that is one of the n plate-like structures A piezoelectric element that generates an electric charge based on deformation of a flexible portion of the n plate-like structures, or at least deformation of a flexible portion of the n-th plate structure, and a specific plate-like structure And a weight provided at the tip of the
The first plate-shaped structure has its own base end directly or indirectly connected to the pedestal,
Among the n plate-like structures, the ka-th plate-like structure (ka is an even number, 2 ≦ ka ≦ n) has a base end of the (ka−1) -th plate-like structure. Connected to the unit via a connector,
The kb-th plate-like structure (kb is an odd number, 3 ≦ kb ≦ n) among the n plate-like structures is a base end of the (kb-1) -th plate-like structure. Connected to the unit via a connector,
A first resonance system is formed by a flexible portion of the first plate-shaped structure and a mass of an object connected to a distal end of the first plate-shaped structure;
The ka-th resonance system is formed by the flexible portion of the ka-th plate-shaped structure and the mass of the object connected to the tip of the ka-th plate-shaped structure,
The kb-th resonance system is formed by the flexible portion of the kb-th plate-like structure and the mass of the object connected to the tip of the kb-th plate-like structure,
A half-width frequency band of each resonance system of the n plate-like structures is entirely or partially overlapped with a half-width frequency band of another resonance system of the plate-like structures. Power generating element. A spring constant of the ka-th plate-shaped structure is smaller than a spring constant of the (ka-1) -th plate-shaped structure;
The power generating element according to claim 4, wherein a spring constant of a flexible portion of the kb-th plate-shaped structure is smaller than a spring constant of a flexible portion of the (kb-1) -th plate-shaped structure. The ka-th plate-shaped structure is different from the (ka-1) -th plate-shaped structure in at least one of a length, a width, and a thickness in a bending direction,
The power generation element according to claim 4, wherein the kb-th plate-shaped structure is different from the (kb-1) -th plate-shaped structure in at least one of length, thickness, and width. N plate-like structures having a flexible portion (n is a natural number of 3 or more), and a pedestal supporting a first plate-like structure that is one of the n plate-like structures A piezoelectric element that generates an electric charge based on the deformation of the flexible portion of the n plate-shaped structures or the deformation of the flexible portion of the plate-shaped structure of the second to n-th plate structures; A weight provided at the tip of the specific plate-like structure,
The first plate-shaped structure has its own base end directly or indirectly connected to the pedestal,
The plate-like structures other than the first plate-like structure have their own base ends connected to the distal end of the first plate-like structure via a connector, respectively.
A first resonance system is formed by a flexible portion of the first plate-shaped structure and a mass of an object connected to a distal end of the first plate-shaped structure;
Due to the flexible portion of the plate-like structure other than the first plate-like structure and the mass of the object connected to the tip of the plate-like structure, a resonance system other than the first resonance system is formed. Formed,
The power generating element according to claim 1, wherein a half-width frequency band of the first resonance system entirely or partially overlaps a half-width frequency band of the another resonance system.   The power generating element according to claim 7, wherein a spring constant of a plate-shaped structure other than the first plate-shaped structure is smaller than a spring constant of the first plate-shaped structure.   The flexible portion of each plate-like structure other than the first plate-like structure has a length, a width, and a thickness in a bending direction that are different from the flexible portion of the first plate-like structure. The power generating element according to claim 7, wherein at least one is different.

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