JP2024148064A - Resonator and vibration power generation device using the resonator - Google Patents

Abstract

The present invention provides a resonator and a vibration power generation device that utilizes vibrations amplified by the resonator by more efficiently transmitting the vibrations to a vibration power generation element.
[Solution] A resonator is provided, comprising a housing having a cavity and an opening communicating with the cavity, and a vibration part provided in the opening and defining a closed space together with the housing, the vibration part resonating by vibrating the air in the closed space with sound pressure. Also provided is a vibration power generation device having a vibration power generation element provided in the vibration part of the resonator.
[Selected Figure] Figure 1

Description

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

Vibration power generation elements that convert vibrational energy into electrical energy are used in electronic devices such as sensors.

The greater the vibration, the more electricity a vibration power generation element can generate. Therefore, in a vibration power generation element that responds to sound, the amount of electricity generated can be increased by increasing the vibration of the sound.

One method for amplifying sound vibrations is the Helmholtz resonator. A Helmholtz resonator consists of a box with a cavity and a neck that is connected to the cavity and has an opening on one side. Sound waves are introduced into the cavity of the box through the neck, causing it to resonate with vibrations of a specific frequency.

A method for amplifying sound energy using a Helmholtz resonator is described in Patent Document 1. In Patent Document 1, a power generation device is installed facing the opening of the Helmholtz resonator, and electricity is generated by vibrating the coil of the power generation device.

Patent No. 4633342

However, in Patent Document 1, the power generation device is installed facing the opening of the Helmholtz resonator, so there is a risk that the sound resonated and amplified by the Helmholtz resonator will attenuate before it leaves the Helmholtz resonator, and before it leaves the Helmholtz resonator and reaches the coil.

In view of these issues, the present invention aims to provide a resonator and a vibration power generation device that more efficiently transmits the vibrations amplified by the resonator to a vibration power generation element and utilizes them.

In order to solve the above problems, a resonator according to one embodiment of the present invention has a housing having a cavity and an opening communicating with the cavity, and a vibrating part that is provided in the opening and defines a closed space together with the housing, and the vibrating part resonates by vibrating the air in the closed space with sound pressure.

In another embodiment of the present invention, a vibration power generation device is provided that includes a vibration power generation element in the vibrating portion of the resonator.

The present invention provides a resonator and a vibration power generation device that more efficiently transmits the vibrations amplified by the resonator to a vibration power generation element and utilizes them.

1A is a perspective view of a vibration-powered energy generator according to a first embodiment of the present invention, and FIG. FIG. 2 is a model diagram of a resonator according to the present invention.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to these.

1. Vibration Power Generation Device Fig. 1(a) is a perspective view of a vibration power generation device 100 according to an embodiment of the present invention, and Fig. 1(b) is a cross-sectional view thereof. As shown in Fig. 1(a), the vibration power generation device 100 includes a resonator 50 and a vibration power generation element 70 provided on the resonator 50. Each component of the vibration power generation device 100 will be described below in order.

In addition, although details will be described later, in this embodiment, the resonator 50 having a closed space and the vibration power generation element 70 are integrally constructed to prevent the sound amplified by the Helmholtz resonator from being attenuated before vibrating the vibration power generation element, as in Patent Document 1.

(Resonator)
The resonator 50 has a housing 20 having a cavity 22 and an opening 24 communicating with the cavity 22, and a vibration part 40 provided in the opening 24 and defining a closed space together with the housing 20.

Here, in the housing 20, the cavity 22 becomes a closed space by providing the vibrating part 40 in the opening 24, and is a space that can resonate as an air spring with the vibration of the vibrating part 40. The housing 20 may be of any shape, for example, a cylindrical shape or a rectangular parallelepiped shape.

The vibration part 40 is less rigid than the housing 20, but is more flexible than the housing 20, and is therefore capable of vibrating when subjected to sound pressure.

The vibration unit 40 may be formed integrally with the other parts of the housing 20 by providing a thin portion in a part of the housing 20. Alternatively, a vibration plate that is a separate part as the vibration unit 40 may be joined to the housing 20 to define a closed space. The method of joining the vibration plate is not limited to this, but may be, for example, adhesive, welding, or screw fastening.

The vibration part 40 may have any shape. For example, it may be disk-shaped or polygonal disk-shaped. As described below, the vibration part 40 is provided with a vibration power generation element 70, and therefore may further have a shape for holding the vibration power generation element 70.

The vibration section 40 may be formed from the same material as the housing 20, or may be formed from a different material. When the housing 20 and the vibration section 40 are formed from the same material, materials such as polyethylene terephthalate (PET), acrylic resin, polycarbonate, and metal can be used. When the housing 20 and the vibration section 40 are formed from different materials, they can be created using a combination of the above materials. For example, the housing 20 may be formed from acrylic resin, and a diaphragm formed from PET may be joined to form the resonator 50.

(Vibration power generation element)
The vibration power generating element 70 is provided in a region of the vibration part 40 where the amplitude becomes large, and generates electricity by vibrating the vibration part 40 due to external sound pressure and further vibrating the vibration amplified by the resonance of the air spring in the closed space. The electric energy generated by the vibration power generating element 70 is transmitted to the outside via wiring (not shown) and can be used for sensor signals, etc.

The vibration power generation element 70 may be any element that converts vibration energy into electrical energy. For example, an electrostatic induction type vibration power generation element having a comb-shaped electrode may be used as the vibration power generation element. In addition to the electrostatic induction type vibration power generation element, the vibration power generation element 70 may also be an electret type power generation element, a piezoelectric type power generation element, an electromagnetic induction type, or a magnetostrictive type power generation element.

The vibration section 40 itself may form the vibration power generation element 70. For example, a piezoelectric vibration power generation element formed by molding a piezoelectric film on the vibration section 40 may be provided.

On the other hand, when an electrostatic induction type vibration power generating element having a comb-tooth electrode is used as the vibration power generating element 70, it is preferable that the vibration direction of the movable electrode of the vibration power generating element 70 coincides with the vibration direction of the vibration part 40. Since the vibration part 40 of one embodiment of the present invention shown in FIG. 1 vibrates in the direction of the double-headed arrow A, the vibration direction of the movable electrode of the vibration power generating element 70 is also set so that it is substantially in the direction of the double-headed arrow A.

(Resonant frequency)
As described above, in the resonator 50, the vibration part 40 vibrates due to the sound pressure from the outside, and the vibration is amplified by the resonance of the air spring in the closed space. The resonant frequency of the resonator 50 will be described below with reference to the model in FIG.

In the model of FIG. 2, a first chamber (resonance chamber) having a closed space surrounded by a housing 55 is adjacent to a second chamber having a closed space via a vibration part 45. The closed space of the first chamber has a volume of _V1 and an internal pressure of _P1 , and the closed space of the second chamber has a volume of _V2 and an internal pressure of _P2 . The second chamber imitates the external space of the first chamber (resonance chamber), and has a relationship of _V2 >> _V1 . The vibration part 45 has a vibrator 80 with a mass m, and the displacement of the vibrator 80 is represented by x. When the vibrator 80 on the vibration part 45 vibrates, the air in the volume _V1 of the first chamber functions as an air spring.

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 vibration unit 45, the following relationship holds. Note that equation (1) is an equation of motion. Equations (2) and (3) show the internal energy of the first and second chambers, respectively. Furthermore, equations (4) and (5) represent the Poisson relationship in the first and second chambers.

Equation 1

( _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 vibration part 45, _V1 : volume of the first chamber _{, V2} : volume of the second chamber, α: coefficient representing the relationship between the displacement of the vibration part 45 and the volume change, γ: specific heat ratio)

Furthermore, assuming that the pressures P ₁ and P ₂ in each chamber change rapidly and uniformly with respect to the displacement of x, the internal energies U ₁ and U ₂ in the first and second chambers can be expressed as follows:

Equation 2

Here, the first term on the right side of equation (6) is constant, and the second term can be interpreted as an air spring _V1 having a spring constant k. Thus, the resonant frequency _f0 of the air spring _V1 in the first chamber can be calculated by the following equation.

Equation 3

In addition, since the above formula (7) is calculated assuming that the pressure in the closed space of the first chamber is uniform, the size of the closed space is preferably smaller than the wavelength of the sound pressure from the outside. In one embodiment, all dimensions constituting the closed space of the first chamber are preferably less than the wavelength λ/4 = c (sound speed)/(4 x f ₀ ). For example, when the resonant frequency f ₀ is 1 kHz, there is no problem if the volume V ₁ is 20 x 20 x 3 mm ³ or less.

(Vibration power generation)
The vibration power generating element 70 can generate power efficiently when subjected to vibrations near a specific resonance frequency. Therefore, in one embodiment of the present invention, the resonance frequency of the vibration power generating element 70 is preferably set to be close to the resonance frequency of the resonator 50. For example, the frequency is 50 Hz to 2000 Hz.

In this way, when the vibration part 40 of the vibration power generation device 100 receives sound pressure that causes resonance of the air spring due to the closed space of the resonator 50, the vibration of the vibration part 40 resonates with the air spring of the resonator 50 and is amplified, allowing the vibration part 40 to vibrate more strongly. As a result, the vibration power generation element 70 installed in the vibration part 40 is vibrated, and power is generated.

The vibration power generation device 100 of this embodiment can be installed anywhere as long as it is in an environment where it can receive sound pressure. It is preferable to install it 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.

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

The above-described embodiment provides the following advantages:

(1) The resonator has 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, and is characterized in that the vibrating part resonates by vibrating the air in the closed space with sound pressure.

This configuration makes it possible to provide a resonator that more efficiently amplifies the vibrations amplified by the resonator.

(2) The vibration part has lower rigidity than other parts of the housing.

Because of this configuration, the vibrating part of the resonator can vibrate when subjected to sound pressure.

(3) The vibration part is thinner than other parts of the housing.

Because of this configuration, the vibration part can be made to have lower rigidity than other parts.

(4) The vibration part is joined to a diaphragm made of a material different from that of the other parts of the housing.

Because of this configuration, the vibration part can be made to have lower rigidity than other parts.

(5) The joining is performed by gluing, welding or screwing.

This configuration allows the diaphragm to be firmly attached to the housing.

(6) The vibration power generation device includes a resonator according to any one of (1) to (5) and a vibration power generation element provided in the vibration part.

Because of this configuration, the vibration power generation device can generate electricity efficiently by using the vibrations of sound pressure amplified by the resonator.

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

This configuration allows the vibration power generation element to generate power efficiently.

(8) The vibration power generation element is a piezoelectric vibration power generation element.

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

Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments that are conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

Furthermore, one or more of the above-mentioned embodiments and variations may be combined as appropriate.

20 Housing 22 Cavity 24 Opening 25 Closed space of first chamber 35 Closed space of second chamber 40 Vibration part 45 Vibration part 50 Resonator 55 Housing 70 Vibration power generation element 80 Vibrator 100 Vibration power generation device

Claims (8)

a housing having a cavity and an opening communicating with the cavity;
a vibration part provided in the opening and defining a closed space together with the housing,
A resonator, characterized in that the vibration part resonates by vibrating the air in the closed space by sound pressure. The resonator according to claim 1, wherein the vibration part has a lower rigidity than other parts of the housing. The resonator according to claim 2, wherein the vibration part is thinner than other parts of the housing. The resonator according to claim 2, wherein the vibration part is joined to a vibration plate made of a material different from that of the other parts of the housing. The resonator according to claim 4, wherein the joining is performed by gluing, welding or screwing. A resonator according to any one of claims 1 to 5,
A vibration power generating element provided on the vibration part;
A vibration power generation device comprising: The vibration power generation device according to claim 6, wherein the vibration direction of the movable element of the vibration power generation element substantially coincides with the vibration direction of the vibration part. The vibration power generation device according to claim 6, wherein the vibration power generation element is a piezoelectric vibration power generation element.

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