Helmholtz resonators and mechanical devices

Abstract

The present invention provides a Helmholtz resonator and mechanical device capable of achieving a broad frequency response. [Solution] The Helmholtz resonator 10 has a body portion 12 in which a cavity 15 is provided inside, a connection port 21 connected to the body portion 12, and an opening 22 connected to the outside, and a throat portion 13 that communicates with the cavity 15 and extends from the connection port 21 to the opening 22, and the throat portion 13 is provided in an offset position away from the center of gravity of the cavity 15 within the connection surface that connects to the body portion 12.

Description

Technical Field

[0001] The present disclosure relates to a Helmholtz resonator and a mechanical apparatus.

Background Art

[0002] Conventionally, a Helmholtz resonator having a housing including a cavity and a neck portion communicating with the cavity is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Helmholtz resonators have a silencing effect that reduces noise. A Helmholtz resonator such as that disclosed in Patent Document 1 suppresses noise through Helmholtz resonance at the resonant frequency. However, since Helmholtz resonators reduce narrowband noise at the resonant frequency, it is difficult to reduce noise across a wide range of frequencies. In particular, when suppressing low-frequency noise, a Helmholtz resonator requires a large cavity (cavity volume), but the narrowband silencing effect means that it cannot be said to have good volumetric efficiency.

[0005] Accordingly, an object of the present disclosure is to provide a Helmholtz resonator and a mechanical apparatus that can achieve broadband (broad) frequency characteristics.

Means for Solving the Problems

[0006] The Helmholtz resonator of this disclosure comprises a body portion having a cavity inside, a connection port connected to the body portion, and an opening connected to the outside, and a throat portion that communicates with the cavity and extends from the connection port to the opening, wherein the throat portion is provided in a connection surface that connects to the body portion, and the connection port is provided at an offset position away from the center of gravity of the cavity.

[0007] The mechanical device of this disclosure comprises the above-described Helmholtz resonator and a device body on which the Helmholtz resonator is provided at the pressure fluctuation site. [Effects of the Invention]

[0008] According to this disclosure, a broad frequency response can be achieved. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a two-view drawing of an example of a Helmholtz resonator according to this embodiment. [Figure 2] Figure 2 is a two-view drawing of an example of a Helmholtz resonator according to this embodiment. [Figure 3] Figure 3 is an example graph showing the frequency characteristics of the Helmholtz resonator according to this embodiment. [Figure 4] Figure 4 is a diagram illustrating an example of a mechanical device equipped with a Helmholtz resonator according to this embodiment. [Figure 5] Figure 5 is a plan view of an example of a Helmholtz resonator according to this embodiment. [Modes for carrying out the invention]

[0010] Embodiments relating to this disclosure will be described in detail below with reference to the drawings. However, the present invention is not limited by these embodiments. Furthermore, some of the components in the embodiments described below are substituted or substantially identical to those easily substituted by those skilled in the art. Moreover, the components described below can be combined as appropriate, and if there are multiple embodiments, each embodiment can be combined.

[0011] [This Circumstance] (Helmholtz resonator) The Helmholtz resonator 10 according to this embodiment is an acoustic module for suppressing noise. Figure 1 is a two-view drawing of an example of a Helmholtz resonator according to this embodiment. As shown in Figure 1, the Helmholtz resonator 10 comprises a body portion 12 in which a cavity 15 is provided inside, and a throat portion 13 connected to the body portion 12.

[0012] The body portion 12 is cylindrical in shape, with a bottom surface and an top surface at both ends in the axial direction. The cavity 15 is the space in which the sound taken into the Helmholtz resonator 10 resonates. The volume V of the cavity 15 is a parameter that defines the resonant frequency of the Helmholtz resonator 10. Although the body portion 12 is cylindrical in shape, it is not particularly limited and may be rectangular in shape as shown in Figure 2.

[0013] The throat section 13 is formed in a cylindrical shape that is narrower than the body section 12, and has a connection port 21 that connects to the body section 12 and an opening 22 that connects to the outside. The connection port 21 and the opening 22 are circular openings. The inside of the throat section 13 is a flow path from the connection port 21 to the opening 22, and the internal flow path communicates with the cavity 15 of the body section 12. The throat section 13 has a throat cross-sectional area S which is the flow path area and a throat length h which is the flow path length. The throat cross-sectional area S and the throat length h are parameters that define the resonance frequency of the Helmholtz resonator 10, and are also parameters that define the natural frequency of the quarter-wave tube, which will be described later.

[0014] In the throat portion 13, on the connection surface connected to the body portion 12 (the lower side in Figure 1), the connection port 21 is provided at an offset position away from the center of gravity of the cavity 15. That is, since the cavity 15 is circular within the connection surface, the center of gravity of the cavity 15 is the center of the circle, and the center of the connection port 21 is provided at an offset position eccentric from the center of the cavity 15. Here, the distance from the center of the connection port 21 to the edge of the cavity 15 passing through the center of the cavity 15 is defined as the eccentric distance L. The eccentric distance L is a parameter that defines the natural frequency of the quarter-wavelength tube described later.

[0015] Figure 3 is a graph showing an example of the frequency characteristics of the Helmholtz resonator according to the present embodiment. As shown in Figure 3, the above Helmholtz resonator 10 has frequency characteristics having a primary mode frequency f0 and a secondary mode frequency f1. The primary mode frequency f0 is the resonance frequency f0 of the Helmholtz resonator 10. The secondary mode frequency f1 is the natural frequency f1 of the quarter-wavelength tube that functions by making the connection port 21 eccentric.

[0016] The resonance frequency f0 is obtained by "f0=(c / 2π)√(S / Vh)". At this time, c is the speed of sound, S is the above-described throat cross-sectional area, V is the above-described cavity volume, and h is the above-described throat length.

[0017] The natural frequency f1 is obtained by "f1=(2n-1)c / 4L1". At this time, c is the speed of sound, (2n-1) is an odd number, and L1 is the distance indicated by the dotted line in Figure 1 (see Figure 1). That is, L1 is a total length of the eccentric distance L, the throat length h, and half the height of the body portion 12 in the axial direction.

[0018] The above parameters are set for the resonance frequency f0 and the natural frequency f1 so that the target noise frequency can be suppressed.

[0019] Note that, in the present embodiment, the case where the body portion 12 has a cylindrical shape has been described, but a Helmholtz resonator 10A as shown in Figure 2 may also be used. Figure 2 is a two-view drawing showing an example of the Helmholtz resonator according to the present embodiment. In the Helmholtz resonator 10A shown in Figure 2, a body portion 12A has a rectangular parallelepiped shape. In the connection surface (the lower side in Figure 2) where the throat portion 13 connects to the body portion 12, a connection port 21 is provided at an offset position away from the center of gravity of the cavity 15. That is, since the cavity 15 is rectangular within the connection surface, the center of gravity of the cavity 15 is the intersection point of the diagonals, and the center of the connection port 21 is provided at an offset position away from the intersection point of the cavity 15. Here, the distance (in the long side direction) from the center of the connection port 21 to the end of the cavity 15 passing through the intersection point of the cavity 15 is defined as an eccentric distance L.

[0020] (Mechanical device) Figure 4 is a diagram related to an example of a mechanical device provided with the Helmholtz resonator according to the present embodiment. The above-described Helmholtz resonator 10 is provided, for example, in a mechanical device that generates operation noise, and is used as a noise suppression module that suppresses the operation noise. An example of the mechanical device is a scroll compressor 30. That is, the scroll compressor 30 as the mechanical device includes the Helmholtz resonator 10 and a compressor main body 31.

[0021] The compressor main body 31 has a spiral stationary blade 34 and a spiral moving blade 35, and two spaces partitioned by the stationary blade 34 and the moving blade 35 serve as two compression chambers 38, and each compression chamber 38 is a pressure fluctuation site where pressure fluctuates.

[0022] The Helmholtz resonator 10 is provided on the outer side of the casing of the compressor main body 31, and is arranged such that the opening 22 of the throat portion 13 is connected to a through hole opened in the casing. For this reason, the cavity 15 of the Helmholtz resonator 10 communicates with the compression chamber 38 of the compressor main body 31. In addition, the Helmholtz resonator 10 is provided at a position that is an antinode of a mode where the operation noise in the compression chamber 38 increases, and specifically, is provided such that the openings 22 are located at both ends of the crescent-shaped (arc-shaped) compression chamber 38.

[0023] In this embodiment, a scroll compressor 30 is used as the mechanical device equipped with the Helmholtz resonator 10, but any mechanical device that generates noise may be used, for example, a gas turbine.

[0024] Furthermore, although one throat portion 13 is provided in the body portion 12 in this embodiment, as shown in Figure 5, multiple throat portions 13 may be provided at different offset positions. Figure 5 is a plan view of an example of a Helmholtz resonator according to this embodiment.

[0025] The Helmholtz resonator 50 shown in Figure 5 comprises the above-mentioned body portion 12 and two throat portions 13a and 13b. One throat portion 13a has an eccentricity distance L1, and the other throat portion 13b has an eccentricity distance L2. As a result, the Helmholtz resonator 50 has a frequency characteristic having a resonant frequency f0 and two different natural frequencies f1. In the Helmholtz resonator 50 shown in Figure 5, two throat portions 13a and 13b are provided, but there is no particular limit to the number of throat portions, and three or more may be provided.

[0026] As described above, the Helmholtz resonators 10, 50 and the mechanical device described in this embodiment can be understood, for example, as follows.

[0027] The Helmholtz resonators 10, 50 according to the first embodiment include a body portion 12 having a cavity 15 inside, a connection port 21 connected to the body portion 12, and an opening 22 connected to the outside, and a throat portion 13 that communicates with the cavity 15 and extends from the connection port 21 to the opening 22, wherein the throat portion 13 is provided at an offset position away from the center of gravity of the cavity 15 within the connection surface connecting to the body portion 12.

[0028] This configuration allows for a broadband frequency response that includes not only the primary mode resonance frequency f0 but also the secondary mode natural frequency f1 of the quarter-wave tube, thus enabling broadband noise suppression.

[0029] In a second embodiment, in the Helmholtz resonators 10 and 50 according to the first embodiment, the body portion 12 is cylindrical in shape, the connecting surface is a circular end face perpendicular to the axial direction of the body portion 12, and the throat portion 13 has the connecting port 21 provided at the offset position eccentric from the center of the end face.

[0030] With this configuration, if the body portion 12 is cylindrical in shape, a broadband frequency characteristic including the resonant frequency f0 and natural frequency f1 can be achieved with a simple configuration in which the connection port 21 is eccentrically positioned from the center of the end face of the body portion 12.

[0031] In a third embodiment, in the Helmholtz resonator 50 according to the first or second embodiment, the throat portion 13 is provided in multiple locations at different offset positions.

[0032] This configuration allows for a frequency response that includes multiple different natural frequencies f1, thus enabling a broader frequency response.

[0033] The mechanical device according to the fourth embodiment comprises the above-described Helmholtz resonators 10 and 50, and a main body of the device on which the Helmholtz resonators 10 and 50 are provided in the pressure fluctuation area.

[0034] This configuration allows for the suppression of operating noise generated from the device itself across a wide frequency range.

[0035] In a fifth embodiment, in the mechanical device according to the fourth embodiment, the device body is a scroll compressor body 31 having the pressure fluctuation section (compression chamber 38).

[0036] This configuration allows for the suppression of operating noise generated by the scroll compressor across a wide bandwidth. [Explanation of symbols]

[0037] 10. Helmholtz resonator 12 Torso 13. Throat section 15 Cavity 21 connection ports 22 Aperture 30 Scroll Compressors 31 Compressor Unit 34 Static Wing 35 Moving blade 38 Compression Chamber

Claims

1. The fuselage section has a cavity inside, It has a connection port connected to the body portion and an opening connected to the outside, and communicates with the cavity, and includes a throat portion extending from the connection port to the opening, The throat portion is a Helmholtz resonator in which the connection port is located at an offset position away from the center of gravity of the cavity within the connection surface that connects to the body portion.

2. The aforementioned body section is cylindrical in shape. The connecting surface is a circular end face perpendicular to the axial direction of the body portion. The Helmholtz resonator according to claim 1, wherein the throat portion has a connection port provided at the offset position eccentrically from the center of the end face.

3. The Helmholtz resonator according to claim 1, wherein the throat portion is provided in multiple locations at different offset positions.

4. A Helmholtz resonator according to any one of claims 1 to 3, A mechanical device comprising: a device body on which the Helmholtz resonator is provided at a pressure fluctuation site.

5. The mechanical device according to claim 4, wherein the device body is a scroll compressor body having the pressure fluctuation portion.

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