Electrical machine wrapped double-layer metamaterial plate

Abstract

The application belongs to the technical field of acoustic metamaterial plate, and particularly relates to a double-layer metamaterial plate wrapped by a motor, which comprises an upper plate and a lower plate, and a resonator group is arranged between the lower plate and the upper plate; the upper plate comprises a first upper plate and a first lower plate arranged in a top-bottom mode, a first gap is arranged between the first upper plate and the first lower plate, the first upper plate and the first lower plate are fixedly connected through four first supporting columns, the lower plate comprises a second lower plate and a second upper plate arranged in a top-bottom mode, a second gap is arranged between the second lower plate and the second upper plate, the second lower plate and the second upper plate are fixedly connected through four second supporting columns, and the resonator group is arranged between the second upper plate and the first lower plate. The acoustic characteristics of the double-layer plate are changed from the structure, the overall sound insulation of the double-layer plate is improved, and meanwhile, the required acoustic characteristics can be obtained by adjusting different parameters.

Description

Technical Field

[0001] This invention belongs to the field of acoustic metamaterial plate technology, and particularly relates to a double-layer metamaterial plate for motor wrapping. Background Technology

[0002] In recent years, my country's high-speed rail, aerospace, and automotive industries have developed rapidly, and noise pollution has attracted widespread attention, impacting people's normal work and lives. To further mitigate the effects of noise on physical and mental health, lightweight thin-plate structures are commonly used for sound insulation, and are widely applied in shipbuilding, automotive, and aerospace industries. High-frequency noise, due to its short wavelength and weak transmission capacity, can be effectively reduced using ordinary lightweight sound-absorbing and insulating materials. However, for mid- and low-frequency noise, ordinary materials typically require a significant increase in weight or thickness to achieve effective noise reduction. In recent years, the development of acoustic metamaterials has offered new solutions for controlling mid- and low-frequency noise. Acoustic metamaterials involve the ordered design of microstructures at the subwavelength physical scale to obtain artificial periodic or aperiodic structures with extraordinary acoustic or mechanical properties not possessed by conventional materials. In 2000, Professor Liu Zhengyou first proposed locally resonant acoustic metamaterials, achieving "small-size control of large wavelengths" and breaking the mass law.

[0003] In existing technologies, automotive motor enclosures typically use traditional sound insulation materials such as fiberglass, expanded polyurethane foam, and sound-absorbing cotton. Because high-frequency noise in motor noise has short wavelengths and weak transmission capabilities, traditional sound insulation materials achieve good noise reduction. However, for mid-to-low frequency noise, ordinary materials usually require a significant increase in weight or thickness to achieve effective noise reduction. Therefore, a device with better sound insulation is needed to enclose the motor, further improving the comfort of electric vehicle passengers.

[0004] Double-layer panels are widely used in automotive acoustic packages and have inherent sound insulation peaks and valleys. To improve the sound insulation defects of double-layer panels, existing methods mostly involve adding damping and sound-absorbing materials to the cavity of the double-layer panel to attenuate sound waves. However, this only improves the sound insulation peaks and valleys of the double-layer panel to a certain extent and still cannot meet the design requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a motor-wrapped double-layer metamaterial plate to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A double-layer metamaterial plate for motor wrapping includes: an upper plate and a lower plate arranged vertically, the lower plate being parallel and symmetrically arranged with respect to the upper plate, and a resonator group being arranged between the lower plate and the upper plate;

[0008] The upper plate includes a first upper plate and a first lower plate arranged vertically. The first upper plate and the first lower plate are parallel and symmetrically arranged. A first gap is provided between the first upper plate and the first lower plate. The first upper plate and the first lower plate are fixedly connected by four first pillars. The four first pillars are located at the four corners of the first upper plate and the first lower plate.

[0009] The lower plate includes a second lower plate and a second upper plate arranged vertically. The second lower plate and the second upper plate are parallel and symmetrically arranged. A second gap is provided between the second lower plate and the second upper plate. The second lower plate and the second upper plate are fixedly connected by four second pillars, which are located at the four corners of the second lower plate and the second upper plate.

[0010] The resonator group is disposed between the second upper plate and the first lower plate.

[0011] Preferably, the resonator group includes a second cylinder and a plurality of first cylinders. The second cylinder is fixed to the side wall of the first lower plate near the second upper plate. The second cylinder is located at the center of the first lower plate and is perpendicular to the first lower plate. A second circular hole is coaxially opened in the second cylinder. The second circular hole passes through the first lower plate and communicates with the first gap.

[0012] Multiple first cylinders are arranged at equal intervals along the circumference of the axis of the second cylinder. Multiple first cylinders are fixed to the side wall of the second upper plate near the first lower plate. The first cylinders are perpendicular to the second upper plate. A first circular hole is coaxially opened in the first cylinder. The first circular hole passes through the second upper plate and communicates with the second gap.

[0013] Preferably, the upper plate and the lower plate are 40mm in length, 40mm in width, and 40mm in height.

[0014] Preferably, the height t of the first gap and the second gap is 0.5mm-1.5mm.

[0015] Preferably, the distance d between the upper plate and the lower plate is 14mm-20mm.

[0016] Preferably, the height h of the first cylinder and the second cylinder is 6mm-8mm, and the radius R is 4.5mm-6.5mm.

[0017] Preferably, the radius r of the first circular hole and the second circular hole is 3mm-5mm.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] This invention structurally alters the acoustic characteristics of the double-layer board, improving its overall sound insulation. Furthermore, the desired acoustic characteristics can be obtained by adjusting different parameters. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the upper plate structure in this invention;

[0023] Figure 3 This is a schematic diagram of the lower layer plate in this invention;

[0024] Figure 4 This is a schematic diagram of the finite element simulation model of the present invention;

[0025] Figure 5 This is a schematic diagram of the finite element sound insulation curve of the present invention;

[0026] Figure 6 The finite element sound insulation performance curves are for the first and second gaps with different thicknesses.

[0027] Figure 7 The finite element sound insulation performance curves are for the first and second cylinders at different heights.

[0028] Figure 8 The finite element sound insulation performance curves are for the first and second cylinders at different radii.

[0029] Figure 9 Finite element sound insulation performance curves for the upper and lower panels at different spacings;

[0030] Among them, 1. upper plate; 2. lower plate; 11. first upper plate; 12. first lower plate; 13. first gap; 14. first support column; 21. second lower plate; 22. second upper plate; 23. second gap; 24. second support column; 3. first cylinder; 31. incident acoustic cavity; 33. transmission acoustic cavity; 34. first plane wave radiation surface; 35. second plane wave radiation surface; 4. second cylinder; 5. first circular hole; 6. second circular hole. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figures 1 to 3 The present invention discloses a double-layer metamaterial plate for motor wrapping, comprising: an upper plate 1 and a lower plate 2 arranged vertically, the lower plate 2 being parallel and symmetrically arranged with the upper plate 1, and a resonator group being arranged between the lower plate 2 and the upper plate 1.

[0034] The upper plate 1 includes a first upper plate 11 and a first lower plate 12 arranged vertically. The first upper plate 11 and the first lower plate 12 are arranged parallel and symmetrically. A first gap 13 is provided between the first upper plate 11 and the first lower plate 12. The first upper plate 11 and the first lower plate 12 are fixedly connected by four first pillars 14. The four first pillars 14 are located at the four corners of the first upper plate 11 and the first lower plate 12.

[0035] The lower plate 2 includes a second lower plate 21 and a second upper plate 22 arranged vertically. The second lower plate 21 and the second upper plate 22 are arranged parallel and symmetrically. A second gap 23 is provided between the second lower plate 21 and the second upper plate 22. The second lower plate 21 and the second upper plate 22 are fixedly connected by four second pillars 24. The four second pillars 24 are located at the four corners of the second lower plate 21 and the second upper plate 22.

[0036] The resonator group is positioned between the second upper plate 22 and the first lower plate 12.

[0037] The scheme is further optimized. The resonator group includes a second cylinder 4 and a plurality of first cylinders 3. The second cylinder 4 is fixed to the side wall of the first lower plate 12 near the second upper plate 22. The second cylinder 4 is located at the center of the first lower plate 12 and is perpendicular to the first lower plate 12. A second circular hole 6 is coaxially opened in the second cylinder 4. The second circular hole 6 passes through the first lower plate 12 and communicates with the first gap 13.

[0038] Multiple first cylinders 3 are evenly spaced circumferentially along the axis of the second cylinder 4. Each first cylinder 3 is fixed to the side wall of the second upper plate 22 near the first lower plate 12. The first cylinders 3 are perpendicular to the second upper plate 22. A first circular hole 5 is coaxially formed within each first cylinder 3, penetrating the second upper plate 22 and communicating with the second gap 23. There are four first cylinders 3.

[0039] The design was further optimized so that the length of the upper plate 1 and the lower plate 2 are 40mm, the width is 40mm, and the height is 40mm.

[0040] The design was further optimized so that the height t of the first gap 13 and the second gap 23 is 0.5mm-1.5mm.

[0041] The design was further optimized so that the spacing d between the upper plate 1 and the lower plate 2 is 14mm-20mm.

[0042] Further optimization of the scheme: the height h of the first cylinder 3 and the second cylinder 4 is 6mm-8mm, and the radius R is 4.5mm-6.5mm.

[0043] Further optimization of the design resulted in the radius r of the first circular hole 5 and the second circular hole 6 being 3mm-5mm.

[0044] One example:

[0045] The upper layer 1 and the lower layer 2 are made of engineering plastics with the following material parameters: density ρ = 1100 kg / m³ 3 Elastic modulus E = 1.9 × 10⁻⁶ 9 Pa; Poisson's ratio ν = 0.35. The upper plate 1, lower plate 2, first cylinder 3, and second cylinder 4 were all fabricated using 3D printing technology.

[0046] Select two engineering plastic sheets with sides of 40mm*40mm and height of 4mm. Cut out a 40mm*39mm*0.5mm and a 39mm*40mm*0.5mm cuboid in the middle of the engineering plastic sheets to obtain the upper plate 1 and the lower plate 2. The distance between the upper plate 1 and the lower plate 2 is 20mm.

[0047] A second cylinder 4 with a radius of 6.5 mm and a height of 8 mm is fixed at the center of the bottom surface of the upper plate 1. A second circular hole 6 with a radius of 5 mm and a height of 8 mm is coaxially hollowed out inside the second cylinder 4. The top of the second circular hole 6 penetrates the first lower plate 12 and communicates with the first gap 13. The distance between the outer wall and bottom wall of the second circular hole 6 and the outer wall and bottom wall of the second cylinder 4 is 1.5 mm (the second circular hole 6 is a hollow cylinder with a wall thickness of 1.5 mm). On the top surface of the lower plate 2... Four first cylinders 3 are fixedly connected to the top, arranged in a 2*2 array. A second cylinder 4 is located in the middle of the four first cylinders 3. Each first cylinder 3 has a coaxially hollowed-out first circular hole 5 with a radius of 5mm and a height of 8mm. The bottom end of the first circular hole 5 penetrates the second upper plate 22 and communicates with the second gap 23. The distance between the outer and bottom walls of the first circular hole 5 and the outer and bottom walls of the first cylinder 3 is 1.5mm (the first cylinder 3 is a hollow cylinder with a wall thickness of 1.5mm). At this point, the surface density of the entire structure is 8.87kg / m³.3 The sound insulation characteristics of this example were analyzed using the acoustic-structure coupling frequency domain analysis module of the large-scale commercial finite element software COMSOL Multiphysics 6.1.

[0048] The boundary conditions of the bilayer metamaterial plate are defined as Floquet periodic boundaries to accurately simulate the actual size and installation conditions of the bilayer metamaterial plate. The entire finite element simulation model is as follows: Figure 4 As shown, the entire model consists of three parts: the incident acoustic cavity 31, the double-layer metamaterial plate unit structure, and the transmission acoustic cavity 33. When a plane sound wave is incident from the first plane wave radiation surface 34, passes through the double-layer metamaterial plate unit structure, and exits from the second plane wave radiation surface 35, the incident acoustic cavity 31 contains the incident sound pressure Pi and the reflected sound pressure Pr, and the transmission acoustic cavity 33 contains the transmitted sound pressure Pt. Therefore, the normal incident sound transmission loss STL of the composite plate can be calculated, as shown in Equation 1 below:

[0049]

[0050] in, For incident sound energy; This represents transmitted sound energy. The incident sound pressure is defined as 1 Pa, the frequency scanning band is 5 Hz-4905 Hz, and the step size is 100 Hz.

[0051] To provide a more intuitive comparison, finite element simulation was performed on the sound insulation of the double-layer metamaterial panel in this example. To ensure that the double-layer metamaterial panel in this example has the same areal density as the traditional double-layer panel, the material parameters and structural dimensions were kept unchanged. Only the traditional double-layer panel was replaced with a double-layer panel with both upper and lower layers having a height of 4mm. Simultaneously, the sound insulation of the homogeneous panel under the same areal density was calculated. The results are as follows: Figure 5 As shown. Compared with homogeneous boards with the same surface density, traditional double-layer boards have a wider sound insulation frequency band in the 500Hz-5000Hz range; compared with traditional double-layer boards, the double-layer metamaterial board in this example has higher sound insulation performance in the 400-1000Hz and 2200Hz-5000Hz ranges.

[0052] Reference Figure 6 Keeping other parameters of the upper plate 1 and the lower plate 2 unchanged, the height t of the first gap 13 and the second gap 23 is changed. The change of the sound insulation curve of the double-layer metamaterial plate is shown in the figure. The first sound insulation peak value of the double-layer metamaterial plate decreases as the height t of the first gap 13 and the second gap 23 increases, and at the same time moves to the lower frequency.

[0053] Reference Figure 7Keeping other parameters of the upper plate 1 and the lower plate 2 unchanged, the height h of the first cylinder 3 and the second cylinder 4 is changed. The sound insulation curve of the double-layer metamaterial plate changes as shown in the figure. Its sound insulation peak value moves to the lower frequency as the height of the hollow column increases.

[0054] Reference Figure 8 Keeping other parameters of the upper plate 1 and the lower plate 2 unchanged, and changing the first circular hole 5 and the second circular hole 6, the sound insulation curve of the double-layer metamaterial plate shifts to the lower frequency as the radius of the first circular hole 5 and the second circular hole 6 increases.

[0055] Reference Figure 9 Keeping other parameters of the upper plate 1 and the lower plate 2 unchanged, the distance d between the upper plate 1 and the lower plate 2 is changed, and its sound insulation curve rises as the distance increases.

[0056] As can be seen from the above description in the embodiments, by changing the relevant parameters of the double-layer metamaterial plate, the sound insulation performance of the material of the present invention can be adjusted, thereby meeting the sound insulation requirements in actual engineering.

[0057] In the embodiments, the upper plate 1 and the lower plate 2 are not limited to cube plates, but can also be plate structures of other geometric shapes.

[0058] Based on the above-mentioned features of the present invention, the double-layer metamaterial board can be applied to the design of sound insulation devices for vehicles and sound insulation design in the field of architecture, etc., to improve people's living environment, especially in the low frequency range, and has good engineering application prospects.

[0059] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0060] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A motor-encased double-layer metamaterial plate, characterized in that, include: An upper plate (1) and a lower plate (2) are arranged vertically, the lower plate (2) is parallel and symmetrical to the upper plate (1), and a resonator group is arranged between the lower plate (2) and the upper plate (1); The upper plate (1) includes a first upper plate (11) and a first lower plate (12) arranged vertically. The first upper plate (11) and the first lower plate (12) are arranged parallel and symmetrically. A first gap (13) is provided between the first upper plate (11) and the first lower plate (12). The first upper plate (11) and the first lower plate (12) are fixedly connected by four first pillars (14). The four first pillars (14) are located at the four corners of the first upper plate (11) and the first lower plate (12). The lower plate (2) includes a second lower plate (21) and a second upper plate (22) arranged vertically. The second lower plate (21) and the second upper plate (22) are arranged parallel and symmetrically. A second gap (23) is provided between the second lower plate (21) and the second upper plate (22). The second lower plate (21) and the second upper plate (22) are fixedly connected by four second pillars (24). The four second pillars (24) are located at the four corners of the second lower plate (21) and the second upper plate (22). The resonator group is disposed between the second upper plate (22) and the first lower plate (12); The resonator assembly includes a second cylinder (4) and a plurality of first cylinders (3). The second cylinder (4) is fixed to the side wall of the first lower plate (12) near the second upper plate (22). The second cylinder (4) is located at the center of the first lower plate (12) and is perpendicular to the first lower plate (12). A second circular hole (6) is coaxially opened in the second cylinder (4). The second circular hole (6) penetrates the first lower plate (12) and communicates with the first gap (13). Multiple first cylinders (3) are arranged at equal intervals along the circumference of the axis of the second cylinder (4). Multiple first cylinders (3) are fixed to the side wall of the second upper plate (22) near the first lower plate (12). The first cylinders (3) are perpendicular to the second upper plate (22). A first circular hole (5) is coaxially opened in the first cylinder (3). The first circular hole (5) penetrates the second upper plate (22) and communicates with the second gap (23). The height h of the first cylinder (3) and the second cylinder (4) is 6mm-8mm, and the radius R is 4.5mm-6.5mm; The radius r of the first circular hole (5) and the second circular hole (6) is 3mm-5mm.

2. The double-layer metamaterial plate for motor wrapping according to claim 1, characterized in that: The upper plate (1) and the lower plate (2) are 40mm long, 40mm wide, and 40mm high.

3. The double-layer metamaterial plate for motor wrapping according to claim 1, characterized in that: The height t of the first gap (13) and the second gap (23) is 0.5mm-1.5mm.

4. The double-layer metamaterial plate for motor wrapping according to claim 1, characterized in that: The distance d between the upper plate (1) and the lower plate (2) is 14mm-20mm.

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