Energy conversion device

Abstract

To provide an energy conversion device capable of generating power by utilizing flutter in which a plate-like vibrator arranged in a fluid vibrates so as to rotate.SOLUTION: The energy conversion device 1 of the present embodiment includes a plate-shaped vibrating plate 3 disposed in the fluid X, an upper spring 4 connected to the 3a of the upper surface of the vibrating plate 3, a lower spring 5 connected to the 3b of the lower surface of the vibrating plate 3, a support frame 2 that supports the upper spring 4 and the lower spring 5, and a piezoelectric device 6 that converts the motion of the vibrating plate 3 into electric power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an energy conversion device. [Background technology]

[0002] Due to the increasing demand for renewable energy, the introduction of solar power generation is progressing in urban areas, for example. On the other hand, much of the energy generated by wind and hydropower is not being recovered. For example, the current mainstream method of wind power generation uses propeller-type rotors, but it is difficult to install multiple wind turbines in close proximity due to the influence of the wake created by the rotation of the rotors. For this reason, wind turbines using propeller-type rotors require a large area of ​​land for installation, making them difficult to install in urban areas.

[0003] In response to this, for example, Patent Document 1 discloses an energy conversion device that utilizes wake galloping. The energy conversion device disclosed in Patent Document 1 includes a stator fixed on the upstream side and an oscillator located downstream of the stator. In addition, the energy conversion device disclosed in Patent Document 1 vibrates the oscillator by the stator fluctuating the flow of wind or water from the upstream side to the downstream side, and converts this vibration into electrical energy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6099240 Summary of the Invention [Problem to be solved by the invention]

[0005] The energy conversion device disclosed in Patent Document 1 generates power by utilizing wake galloping as described above. Specifically, the wake (wake) generated when wind or the like strikes the stator vibrates a downstream oscillator, and the up and down motion of the oscillator is converted into electrical energy. The energy conversion device disclosed in Patent Document 1 is suitable for installation in urban areas because the oscillators can be densely arranged along the flow direction of a fluid such as wind. In addition to galloping, which causes the oscillator to move up and down as described above, flutter, in which a plate-shaped oscillator vibrates in a rotational manner, is another phenomenon in which an oscillator located in a fluid vibrates. However, no energy conversion device that generates power by utilizing such flutter has been proposed to date.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an energy conversion device that can generate electricity by utilizing flutter, which is the rotational vibration of a plate-shaped oscillator placed in a fluid. [Means for solving the problem]

[0007] The present invention employs the following configuration as a means for solving the above problems.

[0008] A first aspect of the present invention is an energy conversion device comprising a plate-shaped vibrator placed in a fluid, a first elastic body connected to one surface of the vibrator, a second elastic body connected to the other surface of the vibrator, a support body supporting the first elastic body and the second elastic body, and a power generation unit that converts the motion of the vibrator into electricity.

[0009] A second aspect of the present invention adopts a configuration in which, in the first aspect, an upstream first elastic body is the first elastic body connected to the upstream portion of the vibrator, a downstream first elastic body is the first elastic body connected to the downstream portion of the vibrator, an upstream second elastic body is the second elastic body connected to the upstream portion of the vibrator, and a downstream second elastic body is the second elastic body connected to the downstream portion of the vibrator.

[0010] A third aspect of the present invention adopts a configuration in which, in the first or second aspect, a plurality of vibration units each consisting of the vibrator, the first elastic body, and the second elastic body are provided along the flow direction of the fluid.

[0011] A fourth aspect of the present invention is the third aspect, wherein the positions of the vibrators in the arrangement direction of the first elastic body, the second elastic body, and the vibrators are different in two adjacent vibration units in the flow direction of the fluid.

[0012] A fifth aspect of the present invention is any one of the first to fourth aspects, in which the vibrator is arranged so that the one surface and the other surface are parallel to the flow direction of the fluid.

[0013] A sixth aspect of the present invention, in any one of the first to fifth aspects, employs a configuration in which the power generating section is a piezoelectric element, which generates power by being deformed by the vibrating vibrator.

[0014] A seventh aspect of the present invention is a configuration in which, in any one of the first to fifth aspects, a protruding member is provided that is connected to the vibrator and protrudes from the vibrator, the protruding member is positioned so as not to overlap the vibrator when viewed from the direction of fluid flow, and the power generating unit is a piezoelectric element that generates electricity by being deformed by the protruding member that vibrates together with the vibrator. [Effects of the Invention]

[0015] According to the present invention, a first elastic body is connected to one surface of a plate-shaped vibrator, and a second elastic body is connected to the other surface of the vibrator. That is, according to the present invention, the plate-shaped vibrator is supported in a state sandwiched between the first elastic body and the second elastic body. When the plate-shaped vibrator supported in this manner is placed in a fluid, it repeatedly rotates so that the upstream end and the downstream end move in opposite directions. That is, according to the present invention, flutter can be generated, in which the plate-shaped vibrator vibrates in a rotational manner. Therefore, according to the present invention, it is possible to generate power by utilizing flutter, in which the plate-shaped vibrator placed in a fluid vibrates in a rotational manner. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic side view showing a schematic configuration of an energy conversion device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic partial perspective view including one diaphragm included in an energy conversion device according to a first embodiment of the present invention. [Figure 3] 1 is a schematic diagram including a diaphragm, an upper spring, a lower spring, and a piezoelectric element included in an energy conversion device according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining various values ​​of the energy conversion device. [Figure 5] (a) is the experimental result of a comparative example with a single diaphragm, (b) is the experimental result of a comparative example with two diaphragms, and (c) is the experimental result based on the first embodiment. [Figure 6] 4 is a graph for explaining the amount of power generation in the first embodiment. [Figure 7] 10 is a bar graph showing amplitude for each side length ratio in Example 2. [Figure 8] 10 is a graph showing changes in amplitude of the first diaphragm and the second diaphragm when the dimensionless wind speed is changed in Example 2. [Figure 9] 1 shows the change in amplitude of the first and second diaphragms when the center-to-center distance is changed by 0.25 in a state in which the first and second diaphragms with a side length ratio of 8 are arranged side by side in Example 2. [Figure 10] FIG. 10 is a schematic partial perspective view including one diaphragm provided in an energy conversion device according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a schematic side view showing a schematic configuration of an energy conversion device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of an energy conversion device according to the present invention will be described with reference to the drawings.

[0018] (First embodiment) FIG. 1 is a schematic side view showing the general configuration of an energy conversion device 1 of this embodiment. The energy conversion device 1 of this embodiment is a power generation device that is placed in a flow path through which a fluid X, such as air, flows to generate power. Note that the fluid X is not limited to air. The fluid X may be a gas or a liquid. Therefore, by taking necessary liquid-proof measures, the energy conversion device 1 of this embodiment can also be placed in a water flow to generate power. As shown in FIG. 1, the energy conversion device 1 of this embodiment includes a support frame 2 (support), a diaphragm 3 (vibrator), an upper spring 4 (first elastic body), a lower spring 5 (second elastic body), a piezoelectric element 6 (power generation unit), and a clamp 7.

[0019] The support frame 2 directly or indirectly supports the vibration plate 3, the upper spring 4, the lower spring 5, the piezoelectric element 6, and the clamp 7. The shape of the support frame 2 is not particularly limited. However, the support frame 2 is formed in a shape that allows the fluid X to flow in the space in which the vibration plate 3 is disposed. In this embodiment, the support frame 2 is formed to form a flow path R through which the fluid X flows, and has an upper portion 2a located above the flow path R, a lower portion 2b located below the flow path R, and a connecting portion 2c that connects the upper portion 2a and the lower portion 2b.

[0020] The diaphragm 3 is a plate-shaped vibrator placed in the flow path R (in the fluid X). The diaphragm 3 is placed so that its front and back surfaces face up and down, and is formed into a rectangular shape when viewed from above. Such a diaphragm 3 has an upper surface 3a (one surface) that faces upward, and a lower surface 3b (the other surface) that faces downward. The diaphragm 3 is supported by upper springs 4 and lower springs 5 ​​so that the upper surface 3a and the lower surface 3b are horizontal. When viewed from above, the diaphragm 3 is formed into a rectangular shape with long sides parallel to the width direction of the flow path R and short sides parallel to the flow direction of the fluid X in the flow path R.

[0021] In this embodiment, the fluid X is supplied horizontally to the energy conversion device 1. Therefore, in this embodiment, the diaphragm 3 is disposed so that the upper surface 3a and the lower surface 3b are parallel to the direction of the flow of the fluid X.

[0022] As shown in FIG. 1, three diaphragms 3 are provided in this embodiment. These diaphragms 3 are arranged at equal intervals along the flow direction of the fluid X. However, the number of diaphragms 3 and the distance between adjacent diaphragms 3 can be changed. In this embodiment, the three diaphragms 3 are arranged at the same height. However, the height of each of the diaphragms 3 can also be changed.

[0023] In the following explanation, for the sake of convenience, the vibration plate 3 located most upstream among the three vibration plates 3 will be referred to as the first vibration plate 31, the vibration plate 3 located second from the upstream side among the three vibration plates 3 will be referred to as the second vibration plate 32, and the vibration plate 3 located most downstream among the three vibration plates 3 will be referred to as the third vibration plate 33.

[0024] Each diaphragm 3 is supported by an upper spring 4 and a lower spring 5. The lower end of the upper spring 4 is connected to the upper surface 3a of the diaphragm 3. The upper end of the lower spring 5 is connected to the lower surface 3b of the diaphragm 3.

[0025] 2 is a schematic partial perspective view including one diaphragm 3. As shown in this figure, four upper springs 4 are connected to the upper surface 3a of the diaphragm 3. Furthermore, four lower springs 5 ​​are connected to the lower surface 3b of the diaphragm 3. In other words, each diaphragm 3 is supported by four upper springs 4 and four lower springs 5. However, the number of upper springs 4 supporting the diaphragm 3 and the number of lower springs 5 ​​supporting the diaphragm 3 can be changed.

[0026] The lower ends of the upper springs 4 are connected to the diaphragm 3 as described above. The upper ends of the upper springs 4 are connected to the upper part 2a of the support frame 2. As shown in FIG. 2, the upper springs 4 are provided at each corner of the rectangular diaphragm 3. In other words, of the four upper springs 4 connected to one diaphragm 3, two are located relatively upstream, and the remaining two are located relatively downstream.

[0027] In the following description, for convenience of explanation, the two upper springs 4 located on the upstream side will be referred to as upstream upper springs 41 (upstream first elastic bodies), and the two upper springs 4 located on the downstream side will be referred to as downstream upper springs 42 (downstream first elastic bodies). In other words, the upstream upper springs 41 are connected to an upstream portion of the diaphragm 3. The downstream upper springs 42 are connected to a downstream portion of the diaphragm 3.

[0028] The two upstream upper springs 41 are formed to have the same length. The two downstream upper springs 42 are also formed to have the same length. The upstream upper springs 41 and the downstream upper springs 42 are also formed to have the same length. In other words, the four upper springs 4 are formed to have the same length.

[0029] The upper ends of the lower springs 5 ​​are connected to the diaphragm 3 as described above. The lower ends of the lower springs 5 ​​are connected to the lower part 2b of the support frame 2. As shown in FIG. 2, the lower springs 5 ​​are provided at each corner of the rectangular diaphragm 3. In other words, of the four upper springs 4 connected to one diaphragm 3, two are located relatively upstream, and the remaining two are located relatively downstream.

[0030] In the following description, for convenience of explanation, the two lower springs 5 ​​located on the upstream side will be referred to as upstream lower springs 51 (upstream second elastic bodies), and the two lower springs 5 ​​located on the downstream side will be referred to as downstream lower springs 52 (downstream second elastic bodies). In other words, the upstream lower springs 51 are connected to an upstream portion of the diaphragm 3. The downstream lower springs 52 are connected to a downstream portion of the diaphragm 3.

[0031] The two upstream-side lower springs 51 are formed to have the same length. The two downstream-side lower springs 52 are also formed to have the same length. The upstream-side lower springs 51 and the downstream-side lower springs 52 are also formed to have the same length. In other words, the four lower springs 5 ​​are formed to have the same length.

[0032] In addition, in this embodiment, the upstream upper spring 41 and the upstream lower spring 51 are arranged so as to overlap when viewed from above. However, it is also possible to arrange the upstream upper spring 41 and the upstream lower spring 51 so as not to overlap when viewed from above. Furthermore, the downstream upper spring 42 and the downstream lower spring 52 are arranged so as to overlap when viewed from above. However, it is also possible to arrange the downstream upper spring 42 and the downstream lower spring 52 so as not to overlap when viewed from above.

[0033] 1, this embodiment includes a plurality of vibration units 10, each of which is made up of one vibration plate 3, four upper springs 4, and four lower springs 5. These vibration units 10 are arranged along the flow direction of the fluid X.

[0034] The piezoelectric element 6 is a power generating unit that converts the motion of the diaphragm 3 into electricity. The piezoelectric element 6 is formed in a thin plate shape and is supported by a clamp 7 in a state where it can abut against the diaphragm 3. In this embodiment, the piezoelectric element 6 is arranged in the flow path R so that it can directly contact the diaphragm 3. Furthermore, as shown in FIG. 2, two piezoelectric elements 6 are provided for one diaphragm 3. However, the number of piezoelectric elements 6 provided for one diaphragm 3 can be changed.

[0035] In this embodiment, these piezoelectric elements 6 are arranged in the flow path R so as to be in direct contact with the vibration plate 3. However, if another member is connected to the vibration plate 3 and vibrates together with the vibration plate 3, it is also possible to arrange the piezoelectric elements 6 outside the flow path R so as to be in contact with the other member.

[0036] Each piezoelectric element 6 is connected to a power storage device Y via a wiring 8. The power storage device Y is a device that stores power, and includes, for example, a bridge circuit, a secondary battery, etc. Power generated by deformation of the piezoelectric elements 6 is supplied to the power storage device Y via the wiring 8 and stored in the power storage device Y. The power storage device Y may be a part of the energy conversion device 1 of this embodiment, or may be a device external to the energy conversion device 1 of this embodiment.

[0037] The clamp 7 supports the piezoelectric element 6. The clamp 7 is fixed to the connection portion 2c of the support frame 2. However, the connection position of the clamp 7 to the support frame 2 is not limited to the connection portion 2c.

[0038] FIG. 3 is a schematic diagram including a diaphragm 3, an upper spring 4, a lower spring 5, and a piezoelectric element 6. As shown in FIG. 3, when a fluid X flows from the upstream side to the downstream side, the diaphragm 3 disposed in the fluid X vibrates in a rotational manner. Here, the diaphragm 3 vibrating in a rotational manner means that each diaphragm 3 continues to rotate, with the upstream end and the downstream end moving in opposite directions, while repeatedly changing the rotation direction. In other words, when the upstream end of the diaphragm 3 moves upward, the downstream end rotates downward, and then when the upstream end moves downward, the downstream end rotates upward, and these movements are repeated as indicated by the arrows in FIG. 3.

[0039] More specifically, for example, when the upstream end of the diaphragm 3 moves upward, the upstream upper spring 41 contracts and the upstream lower spring 51 expands. As a result, the restoring forces of the upstream upper spring 41 and the upstream lower spring 51 act in a direction to move the upstream end of the diaphragm 3 downward. Meanwhile, at this time, the downstream end of the diaphragm 3 moves downward, the downstream upper spring 42 expands, and the downstream lower spring 52 contracts. As a result, the restoring forces of the downstream upper spring 42 and the downstream lower spring 52 act in a direction to move the downstream end of the diaphragm 3 upward. When the restoring forces of the upstream upper spring 41, the upstream lower spring 51, the downstream upper spring 42, and the downstream lower spring 52 increase, the diaphragm 3 is rotated in the opposite direction so that the upstream end of the diaphragm 3 moves downward and the downstream end of the diaphragm 3 moves upward.

[0040] Furthermore, for example, when the upstream end of the diaphragm 3 moves downward, the upstream upper spring 41 expands and the upstream lower spring 51 contracts. As a result, the restoring forces of the upstream upper spring 41 and the upstream lower spring 51 act in a direction to move the upstream end of the diaphragm 3 upward. Meanwhile, at this time, the downstream end of the diaphragm 3 moves upward, the downstream upper spring 42 contracts, and the downstream lower spring 52 expands. As a result, the restoring forces of the downstream upper spring 42 and the downstream lower spring 52 act in a direction to move the downstream end of the diaphragm 3 downward. When the restoring forces of the upstream upper spring 41, the upstream lower spring 51, the downstream upper spring 42, and the downstream lower spring 52 increase, the diaphragm 3 is rotated in the opposite direction so that the upstream end of the diaphragm 3 moves upward and the downstream end of the diaphragm 3 moves downward.

[0041] In the energy conversion device 1 of this embodiment, the flow of the fluid X causes flutter, which is a rotational vibration of the diaphragm 3. In the following description, the rotational vibration of the diaphragm 3 caused by flutter may be referred to as flutter vibration.

[0042] The first diaphragm 31 flutters due to the influence of the flow of fluid X supplied from the upstream side. A wake (wake) is generated in the fluid X that has passed through the first diaphragm 31 as the fluid X separates from the upper surface 3 a and lower surface 3 b of the first diaphragm 31. When the fluid X containing such a wake is supplied to the second diaphragm 32, the second diaphragm 32 vibrates violently. Furthermore, in addition to the wake generated in the first diaphragm 31, a wake is also generated in the fluid X that has passed through the second diaphragm 32 as the fluid X separates from the upper surface 3 a and lower surface 3 b of the first diaphragm 31. The third diaphragm 33 vibrates violently due to either or both of the wake generated by the influence of the first diaphragm 31 and the wake generated by the influence of the second diaphragm 32.

[0043] When such flutter vibration occurs, each diaphragm 3 repeatedly deforms each piezoelectric element 6. As a result, power is generated in each piezoelectric element 6. The power generated in each piezoelectric element 6 is supplied to and stored in the power storage device Y.

[0044] The energy conversion device 1 of this embodiment as described above includes a diaphragm 3, an upper spring 4, a lower spring 5, a support frame 2, and a piezoelectric element 6. The diaphragm 3 is disposed in a fluid X and is formed in a plate shape. The upper spring 4 is connected to an upper surface 3a of the diaphragm 3. The lower spring 5 is connected to a lower surface 3b of the diaphragm 3. The support frame 2 supports the upper spring 4 and the lower spring 5. The piezoelectric element 6 converts the motion of the diaphragm 3 into electric power.

[0045] According to the energy converter 1 of this embodiment, an upper spring 4 is connected to the upper surface 3a of the plate-shaped diaphragm 3, and a lower spring 5 is connected to the lower surface 3b of the diaphragm 3. That is, according to the energy converter 1 of this embodiment, the plate-shaped diaphragm 3 is supported in a state sandwiched between the upper spring 4 and the lower spring 5. When the plate-shaped diaphragm 3 supported in this manner is placed in the fluid X, it repeatedly rotates such that the upstream end and the downstream end move in opposite directions. That is, according to the energy converter 1 of this embodiment, it is possible to generate flutter, in which the plate-shaped diaphragm 3 vibrates in a rotational manner. Therefore, according to the energy converter 1 of this embodiment, it is possible to generate power by utilizing flutter, in which the plate-shaped diaphragm 3 placed in the fluid X vibrates in a rotational manner.

[0046] The energy conversion device 1 of this embodiment also includes an upstream upper spring 41, which is an upper spring 4 connected to an upstream portion of the diaphragm 3. The energy conversion device 1 of this embodiment also includes a downstream upper spring 42, which is an upper spring 4 connected to a downstream portion of the diaphragm 3. The energy conversion device 1 of this embodiment also includes an upstream lower spring 51, which is a lower spring 5 connected to an upstream portion of the diaphragm 3. The energy conversion device 1 of this embodiment also includes a downstream lower spring 52, which is a lower spring 5 connected to a downstream portion of the diaphragm 3.

[0047] According to the energy converter 1 of this embodiment, the upstream end of the diaphragm 3 is supported by the upstream upper spring 41 and the upstream lower spring 51. Furthermore, the downstream end of the diaphragm 3 is supported by the downstream upper spring 42 and the downstream lower spring 52. Therefore, for example, when the upstream end of the diaphragm 3 moves upward, the upstream upper spring 41 contracts and the upstream lower spring 51 expands. At the same time, the downstream end of the diaphragm 3 moves downward, the downstream upper spring 42 expands, and the downstream lower spring 52 contracts. Furthermore, for example, when the upstream end of the diaphragm 3 moves downward, the upstream upper spring 41 expands and the upstream lower spring 51 contracts. At the same time, the downstream end of the diaphragm 3 moves upward, the downstream upper spring 42 contracts, and the downstream lower spring 52 expands. Therefore, in the energy converter 1 of this embodiment, the diaphragm 3 can stably perform flutter vibration.

[0048] Furthermore, the energy conversion device 1 of this embodiment includes a plurality of vibration units 10, each of which is made up of a vibration plate 3, an upper spring 4, and a lower spring 5, arranged along the flow direction of the fluid X. The energy conversion device 1 of this embodiment can vibrate the vibration plate 3 with each of the plurality of vibration units 10, and therefore can generate more power than when a single vibration unit 10 is included.

[0049] Furthermore, in the energy converter 1 of this embodiment, the diaphragm 3 is disposed so that the upper surface 3a and the lower surface 3b are parallel to the flow direction of the fluid X. If the diaphragm 3 is inclined with respect to the flow direction of the fluid X, for example, a difference will occur between the amount of clockwise rotation and the amount of counterclockwise rotation of the diaphragm 3. For this reason, if the diaphragm 3 is inclined with respect to the flow direction of the fluid X, the vibration of the diaphragm 3 may not be stable. In contrast, according to the energy converter 1 of this embodiment, the diaphragm 3 can be stabilized.

[0050] The energy conversion device 1 of this embodiment also includes a piezoelectric element 6 as a power generation unit. The piezoelectric element 6 generates power by being deformed by the vibrating diaphragm 3. The energy conversion device 1 of this embodiment can generate power using the thin-plate shaped piezoelectric element 6, which prevents the power generation unit from obstructing the flow of the fluid X. This allows the diaphragm 3 to vibrate stably.

[0051] The energy conversion device 1 of this embodiment as described above can be installed in a location where there is a flow of fluid X. For example, the energy conversion device 1 of this embodiment may be installed in a location where the flow of fluid X is in a fixed direction. The energy conversion device 1 of this embodiment may also be installed in a location where fluid X flows constantly or periodically. The energy conversion device 1 of this embodiment may also be installed in a location where it cannot be easily reached by the general public. Specifically, the energy conversion device 1 of this embodiment may be installed inside an exhaust duct in a subway station.

[0052] Example 1 Example 1 using the energy conversion device 1 of the first embodiment will be described. In Example 1, a simple, portable extrusion-type wind tunnel device was used as a device for supplying fluid X to the energy conversion device 1. The exhaust passage of the wind tunnel device has a square cross section with sides of 225 mm. The wind tunnel device can also generate wind speeds up to approximately 13 m / s.

[0053] Based on knowledge of the aeroelastic vibration phenomenon of long bridges, a flat plate with a rectangular cross section, which is prone to flutter, was adopted for the diaphragm 3. Figure 4 is a schematic diagram explaining the various values ​​of the energy conversion device 1. The height D of the diaphragm 3 was set to 10 mm. The width B (dimension in the flow direction) of the diaphragm 3 was set to 80 mm. The span L (dimension in the horizontal direction perpendicular to the flow direction) of the diaphragm 3 was set to 300 mm. The spring constant k of the upper spring 4 and the lower spring 5 was set to 0.007 N / mm. The mass m of the diaphragm 3 was set to 38 g. The natural frequency fn for the flutter vibration of the diaphragm 3 was set to 7.8 Hz. The wind speed U of the fluid X was set to 2 to 7 m / s (in 1 m / s increments). The center-to-center distance S of the diaphragm 3 was set to 200 mm.

[0054] In this Example 1, K7520BS3 manufactured by THRIVE was used as the piezoelectric element 6. In this Example 1, the wind speed was changed, so the dimensionless wind speed Vr = U / fnB was used. Furthermore, the experimental results were organized by the double amplitude of the flutter vibration of the diaphragm 3.

[0055] In addition, in this Example 1, for comparison, experiments were also conducted on an example with a single vibration plate 3 (an example with only the first vibration plate 31 of the above embodiment) and an example with two vibration plates 3 (an example with only the first vibration plate 31 of the above embodiment and the second vibration plate 32).

[0056] Fig. 5(a) shows the experimental results of a comparative example with a single diaphragm 3. Fig. 5(b) shows the experimental results of a comparative example with two diaphragms 3. Fig. 5(c) shows the experimental results based on the first embodiment. In the graphs showing these experimental results, the horizontal axis represents the dimensionless wind speed Vr, and the vertical axis represents the amplitude φ' (double amplitude).

[0057] As shown in Figure 5(a), in the comparative example with a single vibrating plate 3, the amplitude suddenly increased at non-dimensional wind speeds of 5 to 10, which is thought to be why flutter occurred. Furthermore, as shown in Figure 5(b), when two vibrating plates 3 were installed, the two vibrating plates 3 showed similar amplitudes in the same range as the single non-dimensional wind speed. When two vibrating plates 3 are installed, the downstream vibrating plate 3 vibrates within the wake generated by the upstream vibrating plate 3. It was not previously known that a vibrating plate 3 would exhibit flutter vibration in this way.

[0058] 5(c), it was found that even when three diaphragms 3 were arranged side by side, all of the diaphragms 3 fluttered. However, at high wind speeds, the first diaphragm 31 and the second diaphragm 32 vibrated to the same extent as in the comparative example, but the amplitude of the third diaphragm 33 was found to be smaller. In this way, it was found that the vibration characteristics changed significantly depending on the position of the diaphragm 3.

[0059] The factors that cause the amplitude of the third diaphragm 33 to decrease were visualized simply using the tufting method. Vinyl string attached to bamboo sticks was used as tufts, and they were placed in the wake of the first diaphragm 31 and the wake of the second diaphragm 32. As a result, it was found that periods of large fluctuations in the flow around the second diaphragm 32 and periods of small fluctuations alternated. Furthermore, it was found that at both times, the flow around the third diaphragm 33 fluctuated less than the flow around the second diaphragm 32. This resulted in differences in the amplitude of the third diaphragm 33, as shown in Figure 5(c).

[0060] Furthermore, in this Example 1, the amount of power generated was measured. Fig. 6 is a graph for explaining the amount of power generated. As shown in this figure, in this Example 1, the maximum power was 13.4 mW. As shown in Fig. 6, it was found that power generation was possible using the energy conversion device 1 of the above embodiment.

[0061] Example 2 Next, Example 2 will be described. In Example 2, an experiment was conducted by installing only the first diaphragm 31 and the second diaphragm 32, without installing the third diaphragm 33. In Example 2, the same wind tunnel device as in Example 1 was used. The height D of the diaphragm 3 was set to 10 mm. Three widths B of the diaphragm 3 were used: 60 mm, 80 mm, and 100 mm. The span L of the diaphragm 3 was set to 300 mm. The spring constant k of the upper spring 4 and the lower spring 5 was set to 0.007 N / mm. The mass m of the diaphragm 3 was set to 28 g. The natural frequency fn for the flutter vibration of the diaphragm 3 was set to 11.75 Hz.

[0062] Figure 7 is a bar graph showing the amplitude (double amplitude) for each side ratio (B / D). Note that the wind speed was set to 7.2 m / s, the maximum value that allows stable experiments. The center-to-center distance (S / B) was set to 2.75.

[0063] As shown in Figure 7, the amplitude of the first diaphragm 31 is large when the side length ratio is 6. On the other hand, it was found that the amplitude of the second diaphragm 32 is large when the side length ratio is 8. Furthermore, when the side length ratio is 10, the amplitude of both the first diaphragm 31 and the second diaphragm 32 is smaller than in other cases. In this way, it was confirmed that the vibration characteristics of the diaphragm 3 can be adjusted by the side length ratio.

[0064] Based on the results of this study, it was found that if the amplitude of the second diaphragm 32 increases, it may be possible to generate electricity more efficiently by arranging three or more diaphragms 3, so further investigation was carried out for a side length ratio of 8. Specifically, experiments were carried out by changing the wind speed.

[0065] Fig. 8 is a graph showing changes in the amplitude of the first diaphragm 31 and the second diaphragm 32 when the dimensionless wind speed Vr is changed. Note that Fig. 8 also shows, as a comparative example, a graph showing changes in the amplitude of the first diaphragm 31 when the dimensionless wind speed Vr is changed in the case of only the first diaphragm 31.

[0066] As a result, when the dimensionless wind speed Vr was in the range of 3.51 to 5.81, the amplitude was smaller when only the first diaphragm 31 was used than when the first diaphragm 31 and the second diaphragm 32 were arranged side by side. This suggests that arranging the two diaphragms 3 side by side made the structure more susceptible to vibration. Furthermore, the amplitude increased sharply when the dimensionless wind speed Vr was between 4.26 and 4.79. This suggests that the flutter phenomenon was particularly pronounced in this range. Furthermore, when the dimensionless wind speed Vr was between 4.79 and 7.13, the amplitude of the first diaphragm 31 and the second diaphragm 32 did not increase significantly.

[0067] It was found that when the dimensionless wind speed Vr was between 7.13 and 7.66, the amplitude of the second diaphragm 32 was larger than that of the first diaphragm 31. This suggests that the effect of wake is stronger in this range. However, in order to generate stable power, it is considered appropriate for the dimensionless wind speed Vr to be between 5.0 and 7.0.

[0068] Next, an experiment was conducted with a dimensionless wind speed Vr of 7.13. Figure 9 shows the change in the amplitude (double amplitude) of the first diaphragm 31 and the second diaphragm 32 when the center-to-center distance (S / B) is changed in increments of 0.25, with the first diaphragm 31 and the second diaphragm 32 having a side-to-side ratio (B / D) of 8 arranged side by side.

[0069] 9, it was found that when the center-to-center distance (S / B) was between 1.75 and 3.0, the second diaphragm 32 had a larger amplitude than the first diaphragm 31. When the center-to-center distance (S / B) was 2.5, the amplitudes of the first diaphragm 31 and the second diaphragm 32 were approximately the same, but the amplitude of the second diaphragm 32 was larger than that of the first diaphragm 31. For this reason, when the side length ratio was 8 and the dimensionless wind speed Vr was 7.13, it was thought that a center-to-center distance (S / B) of 2.5 would provide the best power generation efficiency.

[0070] Thus, it was found from the second embodiment that the amplitude of the second diaphragm 32, which is the downstream diaphragm 3, can be increased.

[0071] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to Fig. 10. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0072] 10 is a schematic partial perspective view including one vibration plate 3 included in the energy conversion device of this embodiment. As shown in this figure, a vibration unit 10A included in the energy conversion device of this embodiment has a projection rod 9 (projection member).

[0073] As shown in Fig. 10, two extension rods 9 are provided for one diaphragm 3. Each extension rod 9 is formed in a rod shape and is provided so as to protrude from the diaphragm 3 in a horizontal direction perpendicular to the flow direction of the fluid X. In other words, each extension rod 9 is arranged so as not to overlap with the diaphragm 3 when viewed from the flow direction of the fluid X.

[0074] Furthermore, in the energy conversion device of this embodiment, the piezoelectric element 6 is arranged so as to be in contact with the extension rod 9. That is, in this embodiment, the piezoelectric element 6 is arranged at a position where it does not overlap with the vibration plate 3 when viewed from the flow direction of the fluid X.

[0075] In the energy conversion device of this embodiment, when the diaphragm 3 vibrates, the extension rod 9 also vibrates in accordance with the vibration of the diaphragm 3. Such vibration of the extension rod 9 deforms the piezoelectric element 6, generating electric power.

[0076] In the energy conversion device of this embodiment as described above, for example, the piezoelectric element 6 can be disposed at a position outside the flow path R. Therefore, the piezoelectric element 6 can be prevented from affecting the flow of the fluid X.

[0077] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Fig. 11. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0078] 11 is a schematic side view showing the general configuration of the energy conversion device 1A of this embodiment. As shown in this figure, in the energy conversion device 1A of this embodiment, the height of the diaphragm 3 differs for each vibration unit 10. That is, in the energy conversion device 1A of this embodiment, the position of the diaphragm 3 in the arrangement direction of the upper springs 4, the lower springs 5, and the diaphragm 3 differs depending on the vibration unit 10.

[0079] In this embodiment, the second diaphragm 32 is positioned above the first diaphragm 31 in the up-down direction. The third diaphragm 33 is positioned below the first diaphragm 31 in the up-down direction.

[0080] According to the energy conversion device 1A of this embodiment, it is possible that the wake generated in the first diaphragm 31 can easily reach the third diaphragm 33. In this case, the amplitude of the third diaphragm 33 may be increased compared to when the third diaphragm 33 and the third diaphragm 34 are disposed at the same height.

[0081] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0082] For example, in the above embodiment, the power generating unit is a piezoelectric element 6. However, the present invention is not limited to this. For example, a coil arranged to surround the upper spring 4 or the lower spring 5 and a magnet provided in the upper spring 4 or the lower spring 5 can also be used as the power generating unit.

[0083] When the upper spring 4 or lower spring 5 equipped with a magnet expands or contracts and moves inside the coil, a current flows in the coil due to electromagnetic induction. Therefore, the coil arranged to surround the upper spring 4 or lower spring 5 and the magnet equipped on the upper spring 4 or lower spring 5 can be used as a power generation unit.

[0084] In the above embodiment, a configuration has been described in which the upper spring 4, which is a helical spring, is used as the first elastic body, and the lower spring 5, which is a helical spring, is used as the second elastic body. However, the present invention is not limited to this. For example, rubber may be used as either or both of the first elastic body and the second elastic body. [Explanation of symbols]

[0085] 1...Energy conversion device, 1A...Energy conversion device, 2...Support frame (support), 3...Vibration plate (vibrator), 3a...Upper surface (one surface), 3b...Lower surface (other surface), 4...Upper spring (first elastic body), 5...Lower spring (second elastic body), 6...Piezoelectric element (power generation unit), 7...Clamp, 8...Wiring, 9...Extending rod (extending member), 10...Vibration unit, 10A...Vibration unit, 31...First vibration plate, 32...Second vibration plate, 33...Third vibration plate, 41...Upstream upper spring (upstream first elastic body), 42...Downstream upper spring (downstream first elastic body), 51...Upstream lower spring (upstream second elastic body), 52...Downstream lower spring (downstream second elastic body), R...Flow path, X...Fluid, Y...Electricity storage device

Claims

1. a plate-shaped vibrator disposed in the fluid; a first elastic body connected to one surface of the vibrator; a second elastic body connected to the other surface of the vibrator; a support body that supports the first elastic body and the second elastic body; a power generation unit that converts the motion of the vibrator into electricity; An energy conversion device comprising:

2. an upstream first elastic body that is the first elastic body connected to an upstream portion of the vibrator; a downstream-side first elastic body that is the first elastic body connected to a downstream portion of the vibrator; an upstream second elastic body that is the second elastic body connected to an upstream portion of the vibrator; a downstream second elastic body that is the second elastic body connected to a downstream portion of the vibrator; 2. The energy conversion device according to claim 1, further comprising:

3. 3. The energy conversion device according to claim 1, wherein a plurality of vibration units, each of which is made up of the vibrator, the first elastic body, and the second elastic body, are provided along the direction of fluid flow.

4. 4. The energy conversion device according to claim 3, wherein the positions of the vibrators in the arrangement direction of the first elastic body, the second elastic body, and the vibrators are different between two of the vibration units adjacent to each other in the flow direction of the fluid.

5. 3. The energy conversion device according to claim 1, wherein the vibrator is disposed so that the one surface and the other surface are parallel to the direction of flow of the fluid.

6. 3. The energy conversion device according to claim 1, wherein the power generating section is a piezoelectric element that generates electricity by being deformed by the vibrating vibrator.

7. a protruding member connected to the vibrator and protruding from the vibrator; the protruding member is disposed so as not to overlap with the oscillator when viewed from the direction of fluid flow, The power generating unit is a piezoelectric element, and generates electricity by being deformed by the protruding member vibrating together with the vibrator.

3. The energy conversion device according to claim 1 or 2.

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