Resonators and vibration power generation devices utilizing resonators

Abstract

To provide a resonator and a vibration power generator which causes vibration amplified by the resonator to reach a vibration power generation element and utilizes the vibration more efficiently.SOLUTION: A resonator is provided having: a housing having a cavity and an opening communicating with the cavity; and a vibration part which is provided at the opening and defines a closed space with the housing. The vibration part vibrates air in the closed space by sound pressure to resonate. Further, a vibration power generator in which a vibration power generation element is provided at the vibration part of the resonator is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to sound vibration power generation using a resonator.

Background Art

[0002] A vibration power generation element that converts vibration energy into electrical energy is used in electronic devices such as sensors.

[0003] The larger the magnitude of the vibration of the vibration power generation element, the larger the power generation amount. Therefore, in a vibration power generation element corresponding to sound, the power generation amount can be increased by increasing the sound vibration.

[0004] One method of increasing the sound vibration is known as a Helmholtz resonator. The Helmholtz resonator includes a box body having a cavity and a neck portion communicating with the cavity and having an opening on one side surface. Sound waves are introduced into the cavity portion of this box body through the neck portion to resonate with vibrations of a specific frequency.

[0005] A method of amplifying sound energy using a Helmholtz resonator is described in Patent Document 1. In Patent Document 1, a power generation device is installed so as to face the opening of the Helmholtz resonator, and power generation is performed by vibrating the coil of the power generation device.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in Patent Document 1, the power generation device is installed facing the opening of the Helmholtz resonator, so there was a risk that the sound resonated and amplified in the Helmholtz resonator would attenuate before it left the Helmholtz resonator and before it reached the coil after leaving the Helmholtz resonator.

[0008] In view of these considerations, the present invention aims to provide a resonator and a vibration power generation device that more efficiently delivers and utilizes the vibrations amplified by the resonator to a vibration power generation element. [Means for solving the problem]

[0009] To solve the above problems, a resonator according to one embodiment of the present invention comprises a housing having a cavity and an opening communicating with the cavity, and a vibrating part provided in the opening and defining a closed space together with the housing, wherein the vibrating part resonates by vibrating the air in the closed space with sound pressure.

[0010] Furthermore, in another embodiment of the present invention, a vibration power generation device is provided that includes a vibration power generation element in the vibrating part of the resonator. [Effects of the Invention]

[0011] The present invention provides a resonator and a vibration power generation device that more efficiently delivers and utilizes the vibrations amplified by the resonator to a vibration power generation element. [Brief explanation of the drawing]

[0012] [Figure 1] (a) A perspective view of a vibration power generation device according to the first embodiment of the present invention. (b) A cross-sectional view along the line Ib-Ib in (a). [Figure 2] This is a model diagram of the resonator of the present invention. [Modes for carrying out the invention]

[0013] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0014] 1. Vibration power generation device Figure 1(a) is a perspective view of a vibration power generation device 100 according to one embodiment of the present invention, and Figure 1(b) is a cross-sectional view thereof. As shown in Figure 1(a), the vibration power generation device 100 comprises a resonator 50 and a vibration power generation element 70 provided in the resonator 50. The various components of the vibration power generation device 100 will be described in order below.

[0015] As will be described in more detail later, in this embodiment, the resonator 50 having a closed space and the vibration power generation element 70 are integrated into one structure, thereby preventing the sound amplified by the Helmholtz resonator from being attenuated before it can vibrate the vibration power generation element, as described in Patent Document 1.

[0016] (resonator) The resonator 50 includes a housing 20 having a cavity 22 and an opening 24 communicating with the cavity 22, and a vibrating part 40 provided in the opening 24 and defining a closed space together with the housing 20.

[0017] Here, in the housing 20, the cavity 22 becomes a closed space when the vibrating part 40 is provided in the opening 24, and is a space that can resonate as an air spring with respect to the vibration of the vibrating part 40. The housing 20 may have any shape, for example, it may be cylindrical or rectangular.

[0018] The vibrating part 40 is less rigid than the housing 20, but more flexible than the housing 20, and therefore can vibrate in response to sound pressure.

[0019] The vibrating section 40 may be formed integrally with the other parts of the housing 20 by providing a thin-walled portion in a part of the housing 20. Alternatively, a diaphragm, which is a separate component, may be joined to the housing 20 as the vibrating section 40, defining a closed space. The method of joining the diaphragm is not limited to this, but for example, adhesive, welding, and screw fastening can be used.

[0020] The vibrating part 40 may have any shape. For example, it may be disc-shaped or polygonal disc-shaped. As will be described later, since the vibration power generation element 70 is provided in the vibrating part 40, it may further have a shape for holding the vibration power generation element 70.

[0021] The vibrating part 40 may be formed of the same material as the housing 20 or may be formed of a different material. When the housing 20 and the vibrating part 40 are formed of the same material, materials such as polyethylene terephthalate (PET), acrylic resin, polycarbonate, and metal can be used. Also, when the housing 20 and the vibrating part 40 are formed of different materials, they can be made of the above material combinations. For example, the housing 20 may be formed of acrylic resin, and a diaphragm formed of PET may be joined to form the resonator 50.

[0022] (Vibration power generation element) The vibration power generation element 70 is provided in a region where the amplitude in the vibrating part 40 becomes large. The vibrating part 40 vibrates due to the sound pressure from the outside, and further vibrates due to the resonance of the air spring in the closed space, and the vibration power generation element 70 generates electricity. The electrical energy generated by the vibration power generation element 70 is transmitted to the outside through wiring (not shown) and can be used for sensor signals and the like.

[0023] Any element can be used as the vibration power generation element 70 as long as it can convert vibration energy into electrical energy. For example, as the vibration power generation element, an electrostatic induction type vibration power generation element having comb-shaped electrodes may be used. Also, in addition to the electrostatic induction type vibration power generation element, the vibration power generation element 70 may use an electret type power generation element, a piezo type power generation element, an electromagnetic induction type, or a magnetostrictive type power generation element.

[0024] Also, the vibrating part 40 itself may form the vibration power generation element 70. For example, a piezoelectric type vibration power generation element in which a piezoelectric film is formed on the vibrating part 40 can be provided.

[0025] On the other hand, when an electrostatic induction type vibration power generation element having comb-shaped electrodes is used as the vibration power generation element 70, it is preferable that the vibration direction of the movable electrode of the vibration power generation element 70 coincides with the vibration direction of the vibration section 40. Since the vibration section 40 of the embodiment of the present invention shown in Figure 1 vibrates in the direction of the double arrow A, the vibration direction of the movable electrode of the vibration power generation element 70 is also set to be substantially in the direction of the double arrow A.

[0026] (resonant frequency) As described above, the resonator 50 vibrates due to external sound pressure in the vibrating part 40, and the vibration is further amplified by the resonance of the air spring within the enclosed space. The resonant frequency of the resonator 50 will be explained below using the model in Figure 2.

[0027] In the model shown in Figure 2, a first chamber (resonance chamber) enclosed by a housing 55 is adjacent to a second chamber, which also has a closed space, via a vibrating section 45. The closed space of the first chamber has a volume V1 and an internal pressure P1, while the closed space of the second chamber has a volume V2 and an internal pressure P2. The second chamber simulates the external space of the first chamber (resonance chamber), and the relationship V2 >> V1 exists. The vibrating section 45 contains an oscillator 80 with mass m, and the displacement of the oscillator 80 is represented by x. When the oscillator 80 on the vibrating section 45 vibrates, the air in the first chamber with a volume V1 functions as an air spring.

[0028] Here, assuming that the air in the closed space is an ideal gas and that the air in the first and second chambers is adiabatically compressed by the vibration of the vibrating part 45, the following relationship holds. Equation (1) is the equation of motion. Equations (2) and (3) show the internal energies of the first and second chambers, respectively. Furthermore, equations (4) and (5) represent the Poisson relation in the first and second chambers. Equation 1

[0029] JPEG0007847560000001.jpg41150(P0: Atmospheric pressure) P1: Pressure in the first chamber P2: Pressure in the second chamber m: Mass of the vibration power generation element 80 x: Displacement of mass m S: Area of ​​the vibrating part 45 V1: Volume of the first room V2: Volume of the second chamber α: A coefficient representing the relationship between the displacement and volume change of the vibrating part 45. γ: specific heat ratio)

[0030] Furthermore, assuming that the pressures P1 and P2 in each chamber change rapidly and uniformly with respect to the displacement x, the internal energies U1 and U2 of the first and second chambers can be expressed as follows: Equation 2

[0031] JPEG0007847560000002.jpg13150

[0032] Here, the first term on the right-hand side of equation (6) is constant, and the second term can be interpreted as an air spring V1 with spring constant k. Thus, the resonant frequency f0 of the air spring V1 in the first chamber can be determined by the following equation: Equation 3

[0033] JPEG0007847560000003.jpg14150

[0034] Furthermore, since equation (7) above is derived assuming that the pressure within the closed space of the first chamber is uniform, it is preferable that the size of the closed space be smaller than the wavelength of the sound pressure from the outside. In one embodiment, it is preferable that all dimensions constituting the closed space of the first chamber be less than the wavelength λ / 4 = c(speed of sound) / (4×f0). For example, when the resonant frequency f0 is 1 kHz, the volume V1 is 20 × 20 × 3 mm 3 The following are acceptable.

[0035] (Vibration power generation) The vibration power generation element 70 can efficiently generate electricity when it receives vibrations near a specific resonant frequency. Therefore, in one embodiment of the present invention, it is preferable that the resonant frequency of the vibration power generation element 70 be matched to the vicinity of the resonant frequency of the resonator 50. For example, 50 Hz to 2000 Hz.

[0036] In this way, when the vibration unit 40 of the vibration power generation device 100 receives sound pressure that causes resonance of the air spring in the enclosed space of the resonator 50, the vibration of the vibration unit 40 resonates with the air spring of the resonator 50 and is amplified, causing the vibration unit 40 to vibrate more strongly. As a result, the vibration power generation element 70 installed in the vibration unit 40 vibrates, and electricity is generated.

[0037] The vibration power generation device 100 of this embodiment can be installed in any location as long as it is in an environment where it can receive sound pressure. Preferably, it is installed in an environment where the effects of external vibrations are suppressed. For example, it may be installed on a material that blocks external vibrations, such as rubber or elastomer, or it may be installed on a device that mechanically blocks vibrations.

[0038] Furthermore, since the vibration power generation device 100 of this embodiment performs resonance in a closed space, it is possible to prevent foreign matter such as water or dust from entering the inside of the resonator.

[0039] According to the embodiments described above, the following effects and advantages are achieved.

[0040] (1) The resonator comprises a housing having a cavity and an opening communicating with the cavity, and a vibrating part provided in the opening and defining a closed space together with the housing, wherein the vibrating part resonates by vibrating the air in the closed space with sound pressure.

[0041] With this configuration, we can provide a resonator that more efficiently amplifies the vibrations amplified by the resonator itself.

[0042] (2) The vibrating part has lower rigidity than the other parts of the housing.

[0043] With this configuration, the vibrating part of the resonator can vibrate in response to sound pressure.

[0044] (3) The vibrating part is thinner than the other parts of the housing.

[0045] With this configuration, the vibrating part can be made with lower rigidity than other parts.

[0046] (4) The vibrating part has a diaphragm made of a different material from the other parts of the housing that is attached to it.

[0047] With this configuration, the vibrating part can be made with lower rigidity than other parts.

[0048] (5) The joining is done by adhesive, welding, or screw fastening.

[0049] This configuration allows the diaphragm to be firmly attached to the housing.

[0050] (6) The vibration power generation device comprises a resonator as described in any one of (1) to (5), and a vibration power generation element provided in the vibrating section.

[0051] With this configuration, the vibration power generation device can efficiently generate electricity through vibrations of sound pressure amplified by the resonator.

[0052] (7) The direction of vibration of the movable element of the vibration power generation element substantially coincides with the direction of vibration of the vibrating part.

[0053] With this configuration, the vibration power generation element can generate electricity efficiently.

[0054] (8) The vibration power generation element consists of a piezoelectric vibration power generation element.

[0055] Because of this configuration, the vibration power generation device can be made smaller.

[0056] Although various embodiments and modifications have been described above, the present invention is not limited to these. It is not the case that other embodiments conceivable within the scope of the technical concept of the present invention are also the present invention. It is included within the range.

[0057] Furthermore, one or more of the above-described embodiments and variations may be combined as appropriate. [Explanation of symbols]

[0058] 20 cabinets 22 Cavity 24 openings 25. Enclosed space in Room 1 35. The enclosed space of Room 2 40 Vibration section 45 Vibration section 50 resonator 55 cabinets 70. Vibration power generation element 80 transducers 100 Vibration power generation device

Claims

1. A housing having a cavity and an opening communicating with the cavity, A resonator having a vibrating part provided to close the aforementioned opening and together with the housing to hermetically define a closed space, The vibrating part is formed integrally with the housing or is hermetically bonded to the housing. The vibrating part vibrates in response to sound pressure from the outside, and the vibration of the vibrating part vibrates the air in the enclosed space, causing the air to resonate as an air spring, and A vibration power generation element provided in the aforementioned vibrating section, A vibration power generation device equipped with [unspecified features].

2. The vibration power generation device according to claim 1, wherein the vibrating part is more flexible than the housing.

3. The vibration power generation device according to claim 2, wherein the vibrating part is thinner than the housing.

4. The vibration power generation device according to claim 2, wherein the vibrating part is a diaphragm formed from a material different from the housing and joined to the housing.

5. The vibration power generation device according to claim 4, wherein the joining is performed by adhesive, welding, or screw fastening.

6. The vibration power generation device according to claim 1, wherein the vibration direction of the movable element of the vibration power generation element substantially coincides with the vibration direction of the vibrating part.

7. The vibration power generation device according to claim 1, wherein the vibration power generation element is a piezoelectric vibration power generation element.

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