Acoustic metamaterial device and device and control method thereof

Abstract

The invention discloses an acoustic metamaterial device and device and a control method of the acoustic metamaterial device, and the acoustic metamaterial device comprises a rigid frame which is provided with a hollow area; the thin film covers the hollow area; the first mass block is fixedly arranged on the thin film and is in contact with the thin film; the second mass block is located above the first mass block, and the second mass block can move relative to the first mass block; when the second mass block moves relative to the first mass block, the working frequency of the acoustic metamaterial device changes. According to the acoustic metamaterial device, the acoustic metamaterial device and the control method of the acoustic metamaterial device, the second mass block is controlled to move relative to the first mass block according to changes of different noise frequencies, the working frequency of the acoustic metamaterial device is changed, and the working frequency of the acoustic metamaterial device is adjusted to the sound insulation frequency. And the purpose of automatically isolating different-frequency noise, especially low-frequency noise, is achieved.

Description

Technical Field

[0001] The present invention relates to the field of acoustic technology, and in particular to an acoustic metamaterial device, an apparatus and a control method thereof. Background Art

[0002] Low-frequency sound waves have the characteristics of long wavelength and difficulty in attenuation during propagation, and are easy to resonate with human organs, causing serious impacts on human health. Traditional sound-absorbing materials are limited by their own acoustic properties and have low efficiency in dissipating low-frequency sound waves. Therefore, to achieve satisfactory low-frequency sound absorption effects, it is necessary to lengthen the propagation path of the sound waves, which will lead to a large thickness of the material, seriously restricting the scope of its engineering application. Acoustic metamaterials have the characteristics of negative equivalent mass density, negative equivalent bulk modulus, negative refraction effect, etc., which can break through the limitations of the mass law of traditional acoustic materials, flexibly and accurately control sound waves, and can use miniaturized and lightweight structures to solve broadband and low-frequency sound insulation problems. However, the performance of acoustic metamaterials is closely related to their structure. Once processed and formed, their structure is fixed, and the function of acoustic metamaterials cannot be changed, which seriously limits their scope of application. Therefore, designing acoustic metamaterial devices with adjustable working frequency and realizing the adjustability of their maximum sound insulation will greatly expand the scope of application of acoustic metamaterial devices.

[0003] At present, the material or structure of acoustic metamaterials is usually changed to achieve the adjustability of their operating frequency. For thin-film acoustic metamaterials, the tension of the film is changed mainly by applying electromagnetic fields, pressure fields, using piezoelectric materials, etc., so as to adjust the natural frequency of the acoustic metamaterial. On the one hand, the adjustment method of the above-mentioned acoustic metamaterial requires complex auxiliary devices, which limits its scope of application; on the other hand, the adjustment range is narrow, and a complete active adjustment system has not been built to achieve adaptive parameter adjustment. Therefore, it is often not feasible in the field of noise control of vehicles and aircraft. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] The present invention provides an acoustic metamaterial device, comprising:

[0006] a rigid frame having a hollow region;

[0007] a film covering the hollow area;

[0008] A first mass block is fixedly disposed on the film and in contact with the film;

[0009] A second mass block, located above the first mass block, and the second mass block is displaceable relative to the first mass block;

[0010] When the second mass block is displaced relative to the first mass block, the operating frequency of the acoustic metamaterial device changes.

[0011] Exemplarily, the acoustic metamaterial device further includes: a control shaft, the second mass block and the first mass block share the control shaft, and when the control shaft rotates, the second mass block rotates relative to the first mass block.

[0012] Exemplarily, the control shaft has no contact with the first mass block, and when the control shaft rotates, the first mass block does not rotate; the control shaft is connected to the second mass block, and when the control shaft rotates, the second mass block rotates.

[0013] Exemplarily, the first mass block and the second mass block are both sector-shaped, and the sector-shaped portion of the first mass block is the same in size and shape as the sector-shaped portion of the second mass block.

[0014] Exemplarily, the film is circular or polygonal, and the center point of the film, the vertex of the first mass block, the vertex of the second mass block and the axis center of the control axis coincide with each other.

[0015] Exemplarily, the angle between the first mass block and the second mass block ranges from 0° to 180°.

[0016] Exemplarily, when the angle between the first mass block and the second mass block increases, the operating frequency of the acoustic metamaterial device decreases.

[0017] Exemplarily, the acoustic metamaterial device further includes: a motor, configured to drive the control shaft to rotate.

[0018] The present invention also provides an acoustic metamaterial device, comprising:

[0019] Acoustic metamaterial devices, including the acoustic metamaterial devices as described above;

[0020] A noise collector is used to obtain environmental noise;

[0021] A controller is used to determine a sound insulation frequency based on the environmental noise and adjust the operating frequency of the acoustic metamaterial device to the sound insulation frequency.

[0022] The present invention also provides a control method for the acoustic metamaterial device as described above, comprising:

[0023] Building a frequency database based on the acoustic metamaterial device;

[0024] Acquiring environmental noise, and determining a sound insulation frequency based on the environmental noise;

[0025] determining a displacement of the second mass block based on the frequency database and the sound insulation frequency;

[0026] The second mass is controlled to move based on the displacement.

[0027] According to the acoustic metamaterial device, apparatus and control method thereof provided by the present invention, according to the change of different noise frequencies, the displacement of the second mass block relative to the first mass block is controlled, the operating frequency of the acoustic metamaterial device is changed, and the operating frequency of the acoustic metamaterial device is adjusted to the sound insulation frequency, thereby achieving the purpose of automatically isolating noises of different frequencies, especially low-frequency noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0029] In the attached figure:

[0030] Figure 1 is a front view of an acoustic metamaterial device according to an embodiment of the present invention;

[0031] Figure 2 is a top view of an acoustic metamaterial device according to an embodiment of the present invention;

[0032] Figure 3 is a schematic structural diagram of a control shaft according to an embodiment of the present invention;

[0033] Figure 4 is a graph showing an acoustic transmission loss of an acoustic metamaterial device according to an embodiment of the present invention;

[0034] Figure 5 is a structural block diagram of an acoustic metamaterial device according to an embodiment of the present invention;

[0035] Figure 6 is a flow chart of a control method of an acoustic metamaterial device according to an embodiment of the present invention;

[0036] Figure 7 1 is a graph showing the operating frequency range and the corresponding acoustic transmission loss of the acoustic metamaterial device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0038] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0039] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0040] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0041] The present invention provides an acoustic metamaterial device 10, such as Figure 1 and Figure 2 As shown, including:

[0042] A rigid frame 11, wherein the rigid frame 11 has a hollow area;

[0043] A film 12 covering the hollow area;

[0044] A first mass block 13 is fixedly disposed on the film 12 and in contact with the film 12;

[0045] A second mass block 14, located above the first mass block 13, and the second mass block 14 can be displaced relative to the first mass block 13;

[0046] When the second mass block 14 is displaced relative to the first mass block 13 , the operating frequency of the acoustic metamaterial device changes.

[0047] Exemplarily, the rigid frame 11 is a hard plastic or metal that can isolate sound transmission, including but not limited to EVA resin, copper, iron, steel, magnet, etc. The rigid frame 11 can be selected into a suitable shape as needed, including but not limited to a circle or a polygon, which is not limited in the present application. The rigid frame 11 has a hollow area.

[0048] Exemplarily, the film 12 is disposed on the rigid frame 11, covering the hollow area of ​​the rigid frame 11, so that the rigid frame 11 supports the film 12. Further, the film 12 matches the shape of the rigid frame 11, and the film 12 is circular or polygonal.

[0049] In one embodiment, Figure 1 and Figure 2 As shown, the rigid frame 11 is in the shape of a ring, with a circular hollow area in the middle of the ring, and the film 12 covers the circular hollow area of ​​the rigid frame 11. Specifically, as shown in FIG. Figure 1 As shown, the film 12 is fixedly connected to the bottom of the rigid frame 11 by gluing. It should be noted that the position (for example, top, upper, middle, lower or bottom) of the film 12 in the rigid frame 11 and the connection method can be selected as needed, and the present application does not limit this.

[0050] In one embodiment, the film 12 includes but is not limited to an elastic plastic film, such as a silicone rubber film, a polyimide film, etc., and its density is 1100 kg / m 3 , Young's modulus is 1.42×10 9 Pa, Poisson's ratio is 0.36.

[0051] Exemplarily, the first mass block 13 and the second mass block 14 are made of metal materials, including but not limited to aluminum, iron, copper, lead, etc. The first mass block 13 and the second mass block 14 are both fan-shaped. Preferably, the fan-shaped part of the first mass block 13 and the fan-shaped part of the second mass block 14 are of the same size and shape, and the connection structure of the fan-shaped center of the first mass block 13 is different from the connection structure of the fan-shaped tail of the second mass block 14. It should be noted that the shape and relative size of the first mass block 13 and the second mass block 14 are only exemplary, and the present application does not limit this. The shape and size of the first mass block 13 and the second mass block 14 can be set or adjusted as needed.

[0052] Exemplarily, the first mass block 13 and the second mass block 14 share a control axis 15, the film 12 is circular or polygonal, and the center point of the film 12, the vertex of the first mass block 13, the vertex of the second mass block 14 and the axis of the control axis 15 coincide.

[0053] In one embodiment, the first mass block 13 and the second mass block 14 are made of iron sheets with a density of 7800 kg / m 3 , Young's modulus is 2×10 11 Pa, Poisson's ratio is 0.3. The film 12 is circular, with a radius of 20 mm and a thickness of 0.2 mm. The first mass block 13 is composed of a sector disk and a through hole ring at the tail of the sector disk, which is adhered to the film 12. The second mass block 14 is composed of a sector disk and a non-through hole ring at the tail of the sector disk. The sector angle of the first mass block 13 and the second mass block 14 is 30°, the sector radius is 15 mm, the sector thickness is 0.5 mm, and the center of the sector is located at the center of the film 32.

[0054] Exemplarily, when the control shaft 15 rotates, the second mass 14 rotates relative to the first mass. Further, the control shaft 15 is not in contact with the first mass 13, and when the control shaft 15 rotates, the first mass 13 does not rotate; the control shaft 15 is connected to the second mass 14, and when the control shaft 15 rotates, the second mass 14 rotates.

[0055] In one embodiment, Figure 3 As shown, a certain gap is reserved between the first mass block 13 and the control shaft 15, and the control shaft 15 has no contact with the first mass block 13, so when the control shaft 15 rotates, the first mass block 13 does not rotate. A certain gap is reserved between the second mass block 14 and the control shaft 15, and the control shaft 15 is used to control the rotation of the second mass block 14. When the control shaft 15 rotates, the second mass block 14 rotates. The rotation angle of the second mass block 14 is controlled by the control shaft 15, and the angle θ between the first mass block 13 and the second mass block 14 is changed. This structure can ensure that the vibration of the acoustic metamaterial device is not affected, and can also ensure that when the control shaft 15 rotates, the second mass block 14 is driven to move.

[0056] Exemplarily, the acoustic metamaterial device further includes a motor 16 , and the motor 16 is used to drive the control shaft 15 to rotate.

[0057] In one embodiment, the motor rotor of the motor 16 directly drives the control shaft 15 to rotate, or the motor 16 drives the transmission mechanism, and the transmission mechanism drives the control shaft 15 to rotate. The transmission mechanism can be composed of a first gear and a second gear. For example, the motor rotor of the motor 16 contacts the first gear, driving the first gear to rotate, the first gear is meshed with the second gear, driving the second gear to rotate, and the second gear contacts the control shaft 15, thereby driving the control shaft 15 to rotate, so that active sound insulation of noise of a specific frequency can be achieved. Among them, the motor rotor or the second gear can be connected to the control shaft 15 by riveting, bonding or direct connection. It should be noted that the way in which the motor 16 drives the control shaft 15 to rotate can be set as needed, and this application does not limit this.

[0058] Reference Figure 4 and Figure 7 As shown in the figure, the acoustic transmission loss (STL) of the acoustic metamaterial device is obtained by solving the finite element software COMSOL. The acoustic power on the incident side and the transmission side is calculated using the acoustic-solid coupling model to obtain the sound insulation of the structure. The incident sound power is calculated by the formula The transmitted sound power is obtained by the formula Calculate, where: P in and P in are the incident and transmitted sound pressures of the plane wave, respectively, and ρc is the characteristic impedance of air. The acoustic transmission loss (STL) is given by the formula The incident sound pressure of the plane wave is set to 1Pa.

[0059] Reference Figure 4 As shown, the angle between the first mass block 13 and the second mass block 14 ranges from 0° to 180°. When the angle θ between the first mass block 13 and the second mass block 14 increases, the operating frequency of the acoustic metamaterial device decreases: when the angle θ between the first mass block 13 and the second mass block 14 changes clockwise from 0°, 40°, 80°, 120°, and 180°, the operating frequency (i.e., the maximum sound insulation frequency) of the acoustic metamaterial device changes to 710Hz, 550Hz, 340Hz, 290Hz, and 260Hz, respectively. In addition, when the value of θ is changed counterclockwise, due to the symmetry of the structure, the change in the operating frequency is the same as that in the clockwise direction.

[0060] Since the acoustic metamaterial device 10 provided by the present invention has a simple structure and a small size, it can achieve low-frequency sound insulation at a low thickness and a small scale, which is beneficial to reducing costs, achieving miniaturization and integration of the device, and expanding the application range of the device.

[0061] The present invention also provides an acoustic metamaterial device 20, such as Figure 5 As shown, including:

[0062] An acoustic metamaterial device 10, comprising the acoustic metamaterial device 10 as described above;

[0063] A noise collector 21 is used to obtain environmental noise;

[0064] The controller 22 is used to determine a sound insulation frequency based on the environmental noise, and adjust the operating frequency of the acoustic metamaterial device 10 to the sound insulation frequency.

[0065] According to the acoustic metamaterial device 20 provided by the present invention, the displacement of the second mass block 14 can be automatically adjusted according to environmental changes, the operating frequency and noise frequency of the device can be matched, and active noise control can be achieved; the operating frequency range can be widened, and the serious disadvantages of single-frequency or narrow-frequency operation of passive acoustic metamaterial devices can be overcome.

[0066] In addition, the present invention also provides a control method for the acoustic metamaterial device 20, such as Figure 6 As shown, the following steps are included:

[0067] Step S31: constructing a frequency database based on the acoustic metamaterial device;

[0068] Step S32: Acquire environmental noise, and determine the sound insulation frequency based on the environmental noise;

[0069] Step S33: determining the displacement of the second mass block based on the frequency database and the sound insulation frequency;

[0070] Step S34: controlling the movement of the second mass block based on the displacement.

[0071] First, step S31 is performed to construct a frequency database based on the acoustic metamaterial device. The designed acoustic metamaterial device 10 is calibrated to determine the relationship between the operating frequency and the rotation angle, and the operating frequency database is constructed. Table 1 shows the frequency database, from which a list of corresponding relationships between the rotation angle θ of the second mass block 14 (i.e., the angle with the first mass block 13) and the operating frequency (i.e., the maximum sound insulation frequency) of the acoustic metamaterial device 10 and the sound insulation amount can be obtained.

[0072] Table 1 Frequency database

[0073]

[0074] As can be seen from Table 1, the acoustic metamaterial device can achieve a sound insulation greater than 45 dB within the range of 260 Hz to 710 Hz. The average noise reduction can reach 56.3 dB, which significantly improves the noise reduction capability of the device.

[0075] Next, step S32 is performed: obtaining environmental noise, and determining the sound insulation frequency based on the environmental noise.

[0076] In one embodiment, the environmental noise is acquired by the noise collector 21, and the acquired environmental noise signal is transmitted to the controller 22 through a signal line (not shown); the controller 22 is used to analyze and process the acquired environmental noise signal to determine the sound insulation frequency. For example, the spectrum characteristics of the environmental noise are analyzed to obtain the noise frequency corresponding to the maximum value of the current noise in the low frequency band, which usually corresponds to the operating frequency of the device.

[0077] Next, step S33 is performed: determining the displacement of the second mass block based on the frequency database and the sound insulation frequency.

[0078] In one embodiment, the controller 22 matches the operating frequency of the acoustic metamaterial device in Table 1 based on the sound insulation frequency obtained in step S32, and further determines the displacement (eg, the rotation angle θ) of the second mass 14 .

[0079] Finally, step S34 is performed: controlling the movement of the second mass block based on the displacement.

[0080] In one embodiment, the controller 22 controls the motor 16 to drive the second mass 14 to rotate to a specified angle, thereby adjusting the acoustic metamaterial device to a specific operating frequency to isolate noise of a specific frequency.

[0081] Reference Figure 7 As shown, when the angle θ between the first mass block 13 and the second mass block 14 increases, the operating frequency of the acoustic metamaterial device decreases, and within the low frequency range of 260-710 Hz, the average noise reduction can reach 56.3 dB, which significantly improves the noise reduction capability of the device.

[0082] According to the acoustic metamaterial device, apparatus and control method thereof provided by the present invention, according to the change of different noise frequencies, the displacement of the second mass block relative to the first mass block is controlled, the operating frequency of the acoustic metamaterial device is changed, and the operating frequency of the acoustic metamaterial device is adjusted to the sound insulation frequency, thereby achieving the purpose of automatically isolating noises of different frequencies, especially low-frequency noise.

[0083] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. An acoustic metamaterial device, characterized in that: include: a rigid frame having a hollow region; a film covering the hollow area; A first mass block is fixedly disposed on the film and in contact with the film; A second mass block, located above the first mass block, and the second mass block is displaceable relative to the first mass block; When the second mass block is displaced relative to the first mass block, the operating frequency of the acoustic metamaterial device changes.

2. The acoustic metamaterial device according to claim 1, characterized in that: Also includes: A control shaft is provided, wherein the second mass block and the first mass block share the control shaft, and when the control shaft rotates, the second mass block rotates relative to the first mass block.

3. The acoustic metamaterial device according to claim 2, characterized in that: The control shaft has no contact with the first mass block, and when the control shaft rotates, the first mass block does not rotate; the control shaft is connected to the second mass block, and when the control shaft rotates, the second mass block rotates.

4. The acoustic metamaterial device according to claim 2, characterized in that: The first mass block and the second mass block are both sector-shaped, and the sector-shaped portion of the first mass block and the sector-shaped portion of the second mass block are the same in size and shape.

5. The acoustic metamaterial device according to claim 4, characterized in that: The film is circular or polygonal, and the center point of the film, the vertex of the first mass block, the vertex of the second mass block and the axis center of the control axis coincide with each other.

6. The acoustic metamaterial device according to claim 5, characterized in that: The angle between the first mass block and the second mass block ranges from 0° to 180°.

7. The acoustic metamaterial device according to claim 4, characterized in that: When the angle between the first mass block and the second mass block increases, the operating frequency of the acoustic metamaterial device decreases.

8. The acoustic metamaterial device according to claim 2, characterized in that: Also includes: The motor is used to drive the control shaft to rotate.

9. An acoustic metamaterial device, characterized in that: include: An acoustic metamaterial device, comprising the acoustic metamaterial device according to any one of claims 1 to 8; A noise collector is used to obtain environmental noise; A controller is used to determine a sound insulation frequency based on the environmental noise and adjust the operating frequency of the acoustic metamaterial device to the sound insulation frequency.

10. A control method for an acoustic metamaterial device as claimed in claim 9, characterized in that: include: Building a frequency database based on the acoustic metamaterial device; Acquiring environmental noise, and determining a sound insulation frequency based on the environmental noise; determining a displacement of the second mass block based on the frequency database and the sound insulation frequency; The second mass is controlled to move based on the displacement.

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