Vehicle sound insulation structure, and vehicle

Abstract

To provide a vehicle sound insulation structure that achieves both weight reduction and high sound insulation, and a vehicle equipped with the vehicle sound insulation structure.SOLUTION: A vehicle sound insulation structure for insulating sound generated from a sound source installed in a vehicle comprises: a first panel comprising a plurality of first tubular sections, having a first main surface on the sound source side and a second main surface opposite the first main surface; a second panel comprising a plurality of second tubular sections, having a third main surface on the sound source side and a fourth main surface opposite the third main surface, and provided closer to the sound source side than the first panel; a porous plate provided between the first main surface and the fourth main surface and having multiple through holes communicating with the first and second tubular sections; a first sound-insulating plate provided on the second main surface; and a second sound-insulating plate provided on the third main surface, where thickness of the second sound-insulating plate is greater than or equal to thickness of the first sound-insulating plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sound insulation structure for a vehicle and a vehicle having the sound insulation structure for a vehicle. [Background technology]

[0002] In recent years, quietness inside a vehicle is often required to ensure comfort for the driver sitting in the driver's seat, or for passengers sitting in the front or rear seats of a vehicle such as a car. In such cases, a sound-insulating structure (sound-insulating material) is provided in the vehicle to block sound from entering the vehicle interior from a sound source such as an engine.

[0003] For example, Patent Document 1 discloses a sound-insulating structure in which, in an architectural structure formed of two flat plate members sandwiching an air layer, a breathable material is installed in a location where the particle velocity of sound is high when the air layer resonates, and the location where the breathable material is installed is a location where the particle velocity is high due to resonance of a desired order n (n is an integer) or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-95759 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, sound insulation structures for vehicles made of metals such as iron and aluminum provide high sound insulation but are heavy and have poor versatility. On the other hand, sound insulation structures for vehicles made of synthetic resins, which are lighter than metals such as iron and aluminum, are lightweight but have poorer sound insulation than sound insulation structures made of metal. For this reason, in order to achieve sound insulation equivalent to that of such sound insulation structures, it becomes necessary to use, for example, an insulator or an asphalt sheet, which often results in an increased weight. In other words, conventional sound insulation structures for vehicles have a trade-off between light weight and high sound insulation, making it difficult to achieve both.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a sound-insulating structure for a vehicle that achieves both lightweight and high sound insulation, and a vehicle that has the sound-insulating structure for a vehicle. [Means for solving the problem]

[0007] In order to solve the above-described problems, according to one aspect of the present disclosure, there is provided a sound-insulating structure for a vehicle that insulates sound generated from a sound source provided in the vehicle, the sound-insulating structure comprising: a first panel made of a plurality of first cylindrical portions and having a first main surface on the sound source side and a second main surface opposite to the first main surface; a second panel made of a plurality of second cylindrical portions and having a third main surface on the sound source side and a fourth main surface opposite to the third main surface, the second panel being provided closer to the sound source than the first panel; a perforated plate having a plurality of through-holes communicating with the first and second cylindrical portions and provided between the first main surface and the fourth main surface; a first sound-insulating plate provided on the second main surface; and a second sound-insulating plate provided on the third main surface, wherein the thickness of the second sound-insulating plate is equal to or greater than the thickness of the first sound-insulating plate.

[0008] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. For example, when it is written as "A to B," the numerical range is "A or more and B or less." [Effects of the Invention]

[0009] As described above, according to the present disclosure, it is possible to provide a vehicle sound-insulating structure that achieves both lightweight and high sound insulation, and a vehicle having the vehicle sound-insulating structure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an exploded perspective view showing an example of the configuration of a sound-insulating structure. [Figure 2] FIG. 2 is a plan view showing a configuration example of a honeycomb core. [Figure 3] FIG. 2 is a plan view showing a configuration example of a honeycomb core. [Figure 4] 1 is an enlarged cross-sectional view showing an example of the configuration of a sound-insulating structure; [Figure 5] FIG. 10 is a diagram showing measurement results of transmission loss of sound-insulating structures according to an example and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1. Embodiment A preferred embodiment of the present disclosure will be described below with reference to the accompanying drawings. The dimensions and scale of each part in the drawings may differ from the actual dimensions. The drawings may be schematic for ease of understanding. Furthermore, the scope of the present disclosure is not limited to the following exemplary embodiments unless otherwise specified.

[0012] In the following description, mutually orthogonal X-axis, Y-axis, and Z-axis are defined. The X-axis, Y-axis, and Z-axis are common to the figures (FIGS. 1 to 4) exemplified in the following description. As exemplified in FIG. 1, one direction along the X-axis as viewed from an arbitrary point is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. Similarly, mutually opposite directions along the Y-axis from an arbitrary point are referred to as the Y1 direction and the Y2 direction, and mutually opposite directions along the Z-axis from an arbitrary point are referred to as the Z1 direction and the Z2 direction.

[0013] The sound insulation structure for a vehicle (hereinafter simply referred to as "sound insulation structure") of the present disclosure is applied to, for example, an electric vehicle, a hybrid vehicle, or a fuel cell vehicle (hereinafter simply referred to as "vehicle") equipped with a PCU (Power Control Unit). Hereinafter, an embodiment in which the sound insulation structure of the present disclosure is applied to such a vehicle will be described. Note that the above-mentioned "electric vehicle, hybrid vehicle, or fuel cell vehicle" is an example of a "vehicle."

[0014] 1 is an exploded perspective view showing an example of the configuration of a sound-insulating structure 10 according to this embodiment. The sound-insulating structure 10 is a sound-insulating material that prevents sound in the frequency band of 8000 to 10800 Hz (hereinafter referred to as inverter sound) generated by an inverter (not shown) for controlling the rotation of the PCU from entering the vehicle interior. The "inverter" is an example of a "sound source."

[0015] The location of the vehicle where the sound-insulating structure 10 is provided is not particularly limited as long as it can prevent inverter noise from entering the vehicle cabin, but it is provided, for example, in a location that separates the interior of the vehicle from the outside, such as the firewall (dashboard) of the vehicle.

[0016] 1, the sound-insulating structure 10 has a perforated plate 11, honeycomb panels 12 and 13, and sound-insulating plates 14 and 15. The stacking order of these members constituting the sound-insulating structure 10, from the inverter side toward the inside of the vehicle cabin, is the sound-insulating plate 15, honeycomb panel 13, perforated plate 11, honeycomb panel 12, and sound-insulating plate 14. In other words, of the sound-insulating plate 15, honeycomb panel 13, perforated plate 11, honeycomb panel 12, and sound-insulating plate 14, the sound-insulating plate 15 is provided closest to the inverter, and the sound-insulating plate 14 is provided closest to the inside of the vehicle cabin.

[0017] (perforated plate) The perforated plate 11 is a flat plate having a rectangular shape when viewed in the Z2 direction, and is provided between the honeycomb panels 12 and 13. The thickness H1 of the perforated plate 11 is not particularly limited, and can be set appropriately depending on the materials of the honeycomb panels and adhesive, which will be described later.

[0018] There are also no particular limitations on the dimension D1 (depth) in the Y-axis direction and the dimension W1 (width) in the X-axis direction of the perforated plate 11. That is, the dimension D1 in the Y-axis direction of the perforated plate 11 and the dimension W1 in the X-axis direction of the perforated plate 11 can be set appropriately depending on the materials of the honeycomb panel and adhesive, which will be described later.

[0019] The porous plate 11 has a plurality of through holes 11a. The through holes 11a are arranged at predetermined intervals in the X-axis direction and the Y-axis direction. Each of the through holes 11a communicates with each of the honeycomb cores 12a. Furthermore, each of the through holes 11a also communicates with each of the honeycomb cores 13a.

[0020] There are no particular limitations on the diameter d of the through holes 11a and the aperture ratio (%) of the through holes 11a. The diameter d of the through holes 11a (see FIG. 4) can be set appropriately depending on the materials of the honeycomb panel and adhesive, which will be described later, from the viewpoint of effectively insulating inverter noise. Similarly, the aperture ratio (%) of the through holes 11a can be set appropriately depending on the materials of the honeycomb panel and adhesive, which will be described later, from the same viewpoint.

[0021] The above "opening ratio (%)" is calculated, for example, by the following formula (1), where W1, D1, r, and q are the width of the perforated plate 11, the depth of the perforated plate 11, the radius of the through holes 11a, and the number of the through holes 11a, respectively.

[0022] Opening ratio (%)=((πr 2 ×q) / (W1×D1))×100 (1)

[0023] The material constituting the perforated plate 11 is not particularly limited, but may be, for example, iron, aluminum, titanium, plastic, CFRP (Carbon Fiber Reinforced Plastics) or GFRP (Glass Fiber Reinforced Plastics), and is typically made of CFRP.

[0024] (Panel 1) The honeycomb panel 12 is a panel with an overall roughly rectangular shape when viewed in the Z2 direction, and is made up of multiple cylindrical honeycomb cores 12a. The honeycomb panel 12 has a main surface S1 (first main surface) and a main surface S2 (second main surface) (see FIG. 4). The honeycomb panel 12 is an example of a "first panel," and the honeycomb cores 12a are an example of a "first cylindrical portion."

[0025] The main surface S1 is the inverter side surface of both surfaces of the honeycomb panel 12. The main surface S1 is made up of the end (end face) of each of the plurality of honeycomb cores 12a on the Z1 direction side. The perforated plate 11 is bonded to the main surface S1. There are no particular limitations on the means for bonding the main surface S1 and the perforated plate 11, and for example, any adhesive may be used to bond the main surface S1 and the perforated plate 11.

[0026] The main surface S2 is the surface facing the interior of the vehicle of both surfaces of the honeycomb panel 12. The main surface S2 is made up of the end (end face) of each of the multiple honeycomb cores 12a on the Z2 direction side. The sound insulation panel 14 is bonded to the main surface S2. There are no particular limitations on the means for bonding the main surface S2 and the sound insulation panel 14, and for example, any adhesive may be used to bond the main surface S2 and the sound insulation panel 14.

[0027] The thickness H2 of the honeycomb panel 12 (height of the honeycomb core 12a) is not particularly limited, but can be set appropriately depending on the materials of the perforated plate and adhesive used, etc., from the viewpoint of effectively blocking inverter noise.

[0028] There are also no particular limitations on the dimension D2 (depth) in the Y-axis direction and the dimension W2 (width) in the X-axis direction of the honeycomb panel 12. That is, the dimension D2 in the Y-axis direction of the honeycomb panel 12 and the dimension W2 in the X-axis direction of the honeycomb panel 12 can be set appropriately depending on the materials of the perforated plate and adhesive used, etc.

[0029] 2 is a plan view showing an example of the configuration of the honeycomb core 12a. The inner diameter 12D (the distance between two opposing sides) of the honeycomb core 12a can be appropriately set from the viewpoint of effectively insulating inverter noise. A space 12E defined by the inner peripheral surface of the honeycomb core 12a around the Z axis communicates with the through-holes 11a of the porous plate 11.

[0030] The honeycomb core 12a may be filled with a filler. The type and amount of filler can be selected appropriately from the viewpoint of vehicle safety, etc. The filler may be any of gas, liquid, and solid. Examples of gaseous fillers include air, nitrogen gas, silica aerogel, etc. The type and amount of filler may be determined appropriately depending on the frequency band of the sound to be insulated. For example, if the sound-insulating structure 10 requires a thin thickness and rigidity, the molecular weight of the gas used as the filler can be specified (for example, a gas with a large molecular weight can be used as the filler) to appropriately accommodate a specific frequency band, such as the frequency band of inverter noise (8000 to 10800 Hz).

[0031] The material constituting the honeycomb panel 12 is not particularly limited, but may be, for example, iron, aluminum, titanium, plastic, CFRP, or GFRP, and is typically made of aluminum.

[0032] (First soundproofing board) The sound insulating plate 14 is a flat plate having a rectangular shape when viewed in the Z2 direction. There are no particular restrictions on the thickness H3 of the sound insulating plate 14 as long as it is thinner than the thickness H4 of the sound insulating plate 15, and it can be set appropriately from the perspective of effectively insulating inverter noise, etc. The sound insulating plate 14 is an example of a "first sound insulating plate."

[0033] There are also no particular limitations on the dimension D4 (depth) in the Y-axis direction and the dimension W4 (width) in the X-axis direction of the sound insulation board 14. The dimension D4 in the Y-axis direction and the dimension W4 in the X-axis direction of the sound insulation board 14 can be set appropriately depending on the materials of the honeycomb panel, perforated board, adhesive, etc. used.

[0034] The material constituting the sound-proofing plate 14 is not particularly limited, but may be, for example, iron, aluminum, titanium, plastic, CFRP or GFRP, and is typically made of CFRP.

[0035] (Second panel) The honeycomb panel 13 is a panel with an overall roughly rectangular shape when viewed in the Z2 direction, and is made up of multiple cylindrical honeycomb cores 13a. The honeycomb panel 13 has a main surface S3 (third main surface) and a main surface S4 (fourth main surface) (see FIG. 4). The honeycomb panel 13 is an example of a "second panel," and the honeycomb cores 13a are an example of a "second cylindrical portion."

[0036] The main surface S3 is the inverter side surface of both surfaces of the honeycomb panel 13. The main surface S3 is made up of the end (end face) of each of the multiple honeycomb cores 13a on the Z1 direction side. A sound insulation plate 15 is bonded to the main surface S3. There are no particular limitations on the means for bonding the main surface S3 and the sound insulation plate 15, and for example, any adhesive may be used to bond the main surface S3 and the sound insulation plate 15.

[0037] The main surface S4 is the surface facing the interior of the vehicle of both surfaces of the honeycomb panel 13. The main surface S4 is made up of the end (end face) of each of the plurality of honeycomb cores 13a on the Z2 direction side. The perforated plate 11 is bonded to the main surface S4. There are no particular limitations on the means for bonding the main surface S4 and the perforated plate 11, and for example, any adhesive may be used to bond the main surface S4 and the perforated plate 11.

[0038] The thickness H3 of the honeycomb panel 13 (height of the honeycomb core 13a) is not particularly limited and is set appropriately from the viewpoint of effectively insulating inverter noise. The thickness H3 and the thickness H2 of the honeycomb panel 12 may be equal to or different from each other.

[0039] There are also no particular limitations on the dimension D3 (depth) in the Y-axis direction and the dimension W3 (width) in the X-axis direction of the honeycomb panel 13. The dimension D3 in the Y-axis direction and the dimension W3 in the X-axis direction of the honeycomb panel 13 can be set appropriately depending on the materials of the perforated plate and adhesive used, etc.

[0040] 3 is a plan view showing an example of the configuration of the honeycomb core 13a. The inner diameter 13D of the honeycomb core 13a (the distance between two opposing sides) can be set appropriately from the viewpoint of effectively insulating inverter noise.

[0041] The inner diameter 13D and the inner diameter 12D of the honeycomb core 12a may be equal to or different from each other. A space 13E defined by the inner peripheral surface of the honeycomb core 13a around the Z axis communicates with the through-holes 11a and the space 12E. That is, the through-holes 11a of the porous plate 11 communicate with the spaces 12E and 13E.

[0042] The material constituting the honeycomb panel 13 is not particularly limited, but may be, for example, iron, aluminum, titanium, plastic, CFRP, or GFRP, and is typically made of aluminum.

[0043] (Second soundproofing board) The sound insulating plate 15 is a flat plate that is rectangular when viewed in the Z2 direction. There are no particular restrictions on the thickness H5 of the sound insulating plate 15 as long as it is equal to or greater than the thickness H4 of the sound insulating plate 14, but it can be set appropriately from the perspective of effectively insulating inverter noise, etc. The sound insulating plate 15 is an example of a "second sound insulating plate."

[0044] There are also no particular limitations on the dimension D5 (depth) in the Y-axis direction and the dimension W5 (width) in the X-axis direction of the sound insulation board 15. The dimension D5 in the Y-axis direction and the dimension W5 in the X-axis direction of the sound insulation board 15 can be set appropriately depending on the materials of the honeycomb panel, perforated board, adhesive, etc. used.

[0045] The material constituting the sound insulating plate 15 is not particularly limited, but may be, for example, iron, aluminum, titanium, plastic, CFRP or GFRP, and is typically made of CFRP.

[0046] Fig. 4 is an enlarged cross-sectional view showing an example of the configuration of the sound insulation structure 10. In the sound insulation structure 10 according to this embodiment, a closed chamber E (a region surrounded by a thick solid line in Fig. 5) is formed by the surface of the sound insulation plate 15 facing the Z2 direction, the inner peripheral surfaces of the honeycomb cores 12a and 13a around the Z axis, the inner peripheral surfaces of the through holes 11a, and the surface of the sound insulation plate 14 facing the Z1 direction. In this embodiment, the thicknesses H4 and H5 of the sound insulation plates 14 and 15, the inner diameters 12D and 13D of the honeycomb cores 12a and 13a, and the diameter d and opening ratio (%) of the through holes 11a are set according to the frequency band of the inverter noise (8000 to 10800 Hz).

[0047] Specifically, the thicknesses H4 and H5 of the sound-insulating plates 14 and 15, the inner diameters 12D and 13D of the honeycomb cores 12a and 13a, and the diameter d and aperture ratio (%) of the through-holes 11a are set to values ​​that cause the honeycomb cores 12a and 13a to vibrate due to Helmholtz resonance caused by inverter noise propagating into the closed chamber E. This effectively insulates the inverter noise, achieving a high level of sound-insulating effect against the inverter noise. In other words, compared to a single-layer plate-like structure, the sound-insulating structure of the present disclosure is expected to have an improved moment of inertia due to its thicker cross section, resulting in improved acoustic performance in the low-frequency range. More specifically, sound generation due to modal resonance can be suppressed, and the influence of transmitted sound due to the coincidence effect can be suppressed, thereby improving sound-insulating performance.

[0048] As explained above, the sound-insulating structure 10 according to this embodiment is a sound-insulating structure for a vehicle that insulates against sound generated from an inverter, and comprises: a honeycomb panel 12 made of a plurality of honeycomb cores 12a and having a main surface S1 on the inverter side and a main surface S2 opposite to the main surface S1; a honeycomb panel 13 made of a plurality of honeycomb cores 13a and having a main surface S3 on the inverter side and a main surface S4 opposite to the main surface S3, the honeycomb panel 13 being disposed on the inverter side of the honeycomb panel 12; a perforated plate 11 having a plurality of through holes 11a communicating with the honeycomb cores 12a, 13a and disposed between the main surface S1 and the main surface S4; a sound-insulating plate 14 provided on the main surface S2; and a sound-insulating plate 15 provided on the main surface S3, wherein the thickness of the sound-insulating plate 15 is equal to or greater than the thickness of the sound-insulating plate 14.

[0049] According to the above embodiment, the thickness H5 of the sound-insulating plate 15 is equal to or greater than the thickness H4 of the sound-insulating plate 14. This improves the sound insulation against inverter noise compared to when the thickness H5 is thinner than the thickness H4. This is apparent from the section (FIG. 5) of the "Example" described later. Furthermore, the honeycomb panels 12, 13 are made of cylindrical honeycomb cores 12a, 13a, and the porous plate 11 is provided with a large number of through holes 11a, thereby reducing the weight of the sound-insulating structure 10. That is, according to this embodiment, the sound-insulating plate 15 is thicker than the sound-insulating plate 14, and the honeycomb panels 12, 13 are made of honeycomb cores, and the porous plate 11 is provided with a large number of through holes 11a, thereby providing the sound-insulating structure 10 with both a light weight and high sound insulation.

[0050] Furthermore, in the sound-insulating structure 10 of this embodiment, a closed chamber E is formed by the sound-insulating plates 14, 15, the inner surfaces of the honeycomb cores 12a, 13a, and the through-holes 11a. According to this aspect, the inverter sound, whose sound energy has been attenuated by the thick sound-insulating plate 15, propagates into the closed chamber E, causing the honeycomb cores 12a, 13a to vibrate by inducing Helmholtz resonance. This further attenuates the inverter sound energy, enabling more effective sound-insulation of the inverter sound. In other words, the inverter sound, whose energy has been attenuated by the thick sound-insulating plate 15, propagates into the closed chamber E and induces Helmholtz resonance, thereby achieving a higher sound-insulating effect against the inverter sound.

[0051] The closed room E is a space sealed by the sound-insulating plates 14 and 15. This prevents moisture and the like from entering the closed room E during rainy weather, for example, and prevents the sound-insulating performance of the sound-insulating structure 10 from deteriorating.

[0052] Furthermore, in the sound-insulating structure 10 of this embodiment, as described above, the honeycomb cores 12a, 13a may be filled with a filler. In this case, by appropriately setting the type or amount of filler depending on the frequency band of the sound to be insulated, it becomes possible to insulate not only inverter noise but also sounds in various frequency bands.

[0053] 2. Variations Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and various modifications may be made. Specific examples of modifications that can be made from the above-described embodiments are given below.

[0054] [Variation 1] In the above embodiment, the sound source to be insulated is an inverter mounted on a PCU (power control unit), but this is not limiting. For example, the sound-insulating structure 10 may be a sound-insulating material that insulates sound in the 11,000 to 12,000 Hz frequency band generated by a micro gas turbine. In this case, the thicknesses H4 and H5 of the sound-insulating plates 14 and 15, the inner diameters 12D and 13D of the honeycomb cores 12a and 13a, and the diameter d and opening ratio (%) of the through-holes 11a may be appropriately set according to the frequency band of the sound generated by the micro gas turbine. In the sound insulation structure 10 according to the first modification, similarly to the sound insulation structure 10 of the above embodiment, the sound insulation plate 15 is thicker than the sound insulation plate 14, the honeycomb panels 12 and 13 are made of honeycomb cores, and a large number of through holes 11a are provided in the perforated plate 11. Therefore, the sound insulation structure 10 according to the first modification can obtain the same effects as those of the above embodiment (combining light weight with high sound insulation).

[0055] [Variation 2] In the above embodiment, the sound source to be insulated is the inverter mounted on the PCU, but this is not limited thereto. For example, the sound-insulating structure 10 may be a sound-insulating material that insulates noise generated by an engine. In this case, the thicknesses H4 and H5 of the sound-insulating plates 14 and 15, the inner diameters 12D and 13D of the honeycomb cores 12a and 13a, and the diameter d and opening ratio (%) of the through-holes 11a may be appropriately set according to the frequency band of the sound generated by the engine. In the sound insulation structure 10 according to the second modification, similarly to the sound insulation structure 10 of the above embodiment, the sound insulation plate 15 is thicker than the sound insulation plate 14, the honeycomb panels 12 and 13 are made of a honeycomb core, and a large number of through holes 11a are provided in the perforated plate 11. Therefore, the sound insulation structure 10 according to the second modification can obtain the same effect as the above embodiment (combining light weight with high sound insulation).

[0056] 3. Supplementary Information The vehicle sound-insulating structure of the present disclosure exemplified in the above embodiment is applied to an electric vehicle, a hybrid vehicle, or a fuel cell vehicle, but the vehicle sound-insulating structure of the present disclosure may also be applied to vehicles other than the above vehicles, and the uses of the present disclosure are not particularly limited.

[0057] Furthermore, the effects described herein are merely descriptive or exemplary and not limiting, meaning that the present disclosure may provide other effects in addition to or in place of the above-described effects that would be apparent to one skilled in the art from the description herein.

[0058] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technology of the present disclosure is not limited to the above embodiments. It is clear that a person skilled in the art of the technology to which the present disclosure pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. [Example]

[0059] The above embodiment will be specifically described below based on examples, but the present disclosure is not limited to the following description.

[0060] [Creating sound insulation structures] Example 1 The sound-insulating structure 10 according to Example 1 was obtained through the following steps 1 to 6. Note that there are no particular restrictions on the order in which the following steps 1 to 5 are performed.

[0061] (Step 1) An aluminum honeycomb panel 12 (thickness H2: 20 mm, inner diameter 12D of honeycomb core 12a: 60 mm) was prepared.

[0062] (Step 2) An aluminum honeycomb panel 13 (thickness H3: 20 mm, inner diameter 13D of honeycomb core 13a: 60 mm) was prepared.

[0063] (Step 3) A CFRP plate was prepared and cut to a predetermined size to obtain a CFRP plate with a thickness H1 of 5.4 mm (8 ply). Next, a plurality of through holes 11a (diameter d: 0.2 mm (0.2φ)) were formed at predetermined intervals to obtain a perforated plate 11.

[0064] (Step 4) A CFRP plate was prepared and cut to a predetermined size to obtain a sound insulating plate 14 having a thickness H4 of 2.7 mm (4 ply).

[0065] (Step 5) A CFRP plate was prepared and cut to a predetermined size to obtain a sound insulation plate 15 having a thickness H5 of 5.4 mm (8 ply).

[0066] (Step 6) The honeycomb panels 12, 13, the perforated plate 11, and the sound-insulating plates 14, 15 obtained by steps 1 to 5 above were stacked in the order of sound-insulating plate 15, honeycomb panel 13, perforated plate 11, honeycomb panel 12, and sound-insulating plate 14 from the sound source side to form a sound-insulating structure 10. The sound-insulating plate 15 and honeycomb panel 13, the honeycomb panel 13 and perforated plate 11, the perforated plate 11 and honeycomb panel 12, and the honeycomb panel 12 and sound-insulating plate 14 were joined together using an adhesive.

[0067] <Example 2> A sound-insulating structure 10 according to Example 2 was obtained in the same manner as in Example 1, except that the thickness H5 of the sound-insulating plate 15 was set to 2.7 mm (4 ply).

[0068] <Comparative Example> A sound insulating structure according to the comparative example was obtained in the same manner as in Example 1, except that the thickness H4 of the sound insulating plate 14 was set to 5.4 mm (8 ply) and the thickness H5 of the sound insulating plate 15 was set to 2.7 mm (4 ply).

[0069] [Transmission loss measurement] Next, the sound transmission loss TL (dB) of the sound insulation structures 10 according to Examples 1 and 2 and the sound insulation structure according to the comparative example was measured. The sound transmission loss was measured by the random incidence method in accordance with JIS A 1409:1998. A known speaker (T925 model manufactured by FOSTEX) and an air nozzle were used as the sound source, and analysis was performed using measurement software. The measurement results are shown in FIG.

[0070] 5, it can be seen that the sound insulation structures 10 according to Examples 1 and 2 have a transmission loss TL (dB) for sound in the relatively low frequency band of 3000 to 6000 Hz and sound in the relatively high frequency band of 8000 to 20000 Hz, including inverter sound, that is clearly greater than that of the sound insulation structure according to the comparative example. This result shows that by making the thickness of sound insulation board 15 equal to or greater than the thickness of sound insulation board 14, sounds in the low and high frequency bands can be sufficiently insulated. [Explanation of symbols]

[0071] 10...Sound insulation structure for vehicles 11...Perforated plate 11a...Through hole 12...Honeycomb panel (first panel) 12a...Honeycomb core (first cylindrical portion) 13...Honeycomb panel (second panel) 13a...Honeycomb core (second cylindrical portion) 14...Soundproofing board (first soundproofing board) 15...Soundproofing board (second soundproofing board) S1...Main surface (first main surface) S2...Main surface (second main surface) S3: Main surface (third main surface) S4...Main surface (fourth main surface)

Claims

1. A sound-insulating structure for a vehicle that insulates sound generated from a sound source provided in the vehicle, a first panel including a plurality of first cylindrical portions and having a first main surface on the sound source side and a second main surface opposite to the first main surface; a second panel including a plurality of second cylindrical portions and having a third main surface on the sound source side and a fourth main surface opposite to the third main surface, the second panel being provided closer to the sound source than the first panel; a porous plate having a plurality of through holes communicating with the first and second cylindrical portions and disposed between the first main surface and the fourth main surface; a first sound-insulating plate provided on the second main surface; a second sound-insulating plate provided on the third main surface, The thickness of the second sound-insulating plate is equal to or greater than the thickness of the first sound-insulating plate. Sound insulation structure for vehicles.

2. the first and second panels are honeycomb panels; the first and second cylindrical portions are honeycomb cores, The first sound-insulating plate, the inner surface of the first cylindrical portion, the through hole, the inner surface of the second cylindrical portion, and the second sound-insulating plate form a closed chamber. The sound insulating structure for a vehicle according to claim 1.

3. 3. The vehicle sound insulating structure according to claim 2, wherein the honeycomb core is filled with a filler material.

4. 4. The vehicle sound-insulating structure according to claim 1, wherein the sound source is an inverter mounted on a micro gas turbine, an engine, or a power control unit.

5. A vehicle comprising the vehicle sound insulation structure according to any one of claims 1 to 3.

Images