JP7383997B2 - Soundproofing member and its manufacturing method - Google Patents

Description

The present invention relates to a soundproofing member including a first soundproofing part suitable for soundproofing high-frequency sound and a second soundproofing part suitable for soundproofing sound of a frequency different from that of the first soundproofing part, and a method for manufacturing the same.

This type of soundproofing member is used in various structures from the viewpoint of noise countermeasures, and is particularly suitable for use as a component of a vehicle. In the field of soundproofing materials, there is a demand for soundproofing (absorbing or insulating) noise at a wide range of frequencies. The challenge is how to secure it.

For example, in the technique disclosed in Patent Document 1, an acoustic gap suitable for soundproofing low frequency sounds is provided in a foam having an open cell structure suitable for soundproofing high frequency sounds. In other words, the thermosetting soundproofing paint composition (hereinafter referred to as the composition) of the same technology is a foam with an open cell structure mainly composed of urethane resin, etc., and is used as a filler for various structures. . The surface of this composition is formed of a surface layer provided with micropores, and a plurality of acoustic holes having an appropriate volume are formed under this surface layer. The composition of Patent Document 1 is capable of absorbing high frequency sound due to the foam having an open cell structure, and is suitable for soundproofing, for example, sounds of 1000 Hz or higher. Furthermore, the low-frequency sound propagated to each acoustic hole through the micropores is attenuated and absorbed using the Helmholtz resonance principle.

Further, the molded product disclosed in Patent Document 2 is a solid resin molded plate used as an engine shield, and has a plate-shaped outer surface forming an outer shape and a plurality of chambers arranged inside this outer surface. have. This molded product uses the Helmholtz resonance principle to absorb low-frequency sound in each room by providing through holes on the side facing the engine room of each room. In the technique disclosed in Patent Document 2, a nonwoven fabric is attached around each chamber, and this nonwoven fabric enables high-frequency sound to be absorbed.

JP2012-255967A Patent No. 2522606

By the way, it is preferable that the above-mentioned soundproofing member has appropriate rigidity, assuming that it will be used in a wide range of applications such as a component of a vehicle. However, since the composition of Patent Document 1 is a foam for a filler, the composition is unsuitable for ensuring rigidity. However, as in the technique of Patent Document 2, it is also conceivable to form a soundproofing member using a solid resin and attaching a nonwoven fabric to this soundproofing member. However, there is a certain limit to the adhesive strength between the nonwoven fabric and the soundproofing member, and if the nonwoven fabric peels off for some reason, there is a possibility that desired soundproofing properties cannot be secured. The present invention has been devised in view of the above-mentioned points, and the problem to be solved by the present invention is to enable soundproofing against a wide range of frequencies while ensuring the rigidity of a soundproofing member.

As a means for solving the above problems, the soundproofing member of the first invention includes a first soundproofing part suitable for soundproofing high-frequency sound, and a second soundproofing part suitable for soundproofing sound of a frequency different from that of the first soundproofing part. It is equipped with In this type of configuration, it is desired that the soundproofing member be able to soundproof a wide range of frequencies while ensuring the rigidity of the soundproofing member.

Therefore, the soundproofing member of the present invention is an integrally molded product of a first soundproofing part made of a foamed resin having an open cell structure and a second soundproofing part having a hollow structure and having higher rigidity than the first soundproofing part. . The first soundproofing section is integrated around the second soundproofing section with the opening of the hollow structure exposed. Further, the second soundproofing part of the soundproofing member of the first invention has an opening at one end, and the other end opposite to the one end is closed by a lid part. The lid part is integrally formed with the second soundproofing part via an integral hinge part provided on one edge that forms part of the outer edge of the second soundproofing part, and extends outward from the hollow structure. The hollow structure is brought into a closed state by being folded back from the original state using the integral hinge part as a base point, and the second soundproofing part is connected to the second soundproofing part via a latch structure provided on the outer edge portion of the second soundproofing part opposite to one edge. In the latch structure, a locking protrusion formed integrally with the second soundproofing part is locked in a locking hole formed integrally with the lid. The soundproofing member of the present invention is an integrally molded product of a first soundproofing part and a second soundproofing part, and the first soundproofing part is arranged around the second soundproofing part and is relatively firmly integrated with the second soundproofing part. Therefore, the first soundproofing section can perform soundproofing against high-frequency sounds while being reinforced by the second soundproofing section. Further, in the present invention, since the second soundproofing part has a hollow structure, it is suitable for soundproofing from sounds of a different frequency (for example, low frequency sound) from the first soundproofing part by utilizing the Helmholtz resonance principle. It is. That is, since the opening of the hollow structure is exposed from the first soundproofing part, it is possible to attenuate the sound incident on the opening within the hollow structure and absorb the sound. In addition, in the present invention, by integrally forming the lid part that closes the hollow structure on either the first sound insulation part or the second sound insulation part, the number of parts of the sound insulation member can be reduced, and the structure can be simplified. The structure is conducive to

A soundproofing member according to a second aspect of the invention is the soundproofing member according to the first invention, in which the second soundproofing part is formed of a member in which a plurality of cellulose fibers are integrated in a laminated state. The second soundproofing part of the present invention is made of cellulose fiber that has excellent soundproofing properties and is lighter than resin or metal, so it has a configuration that contributes to improving the performance of the soundproofing member.

In the soundproofing member of the third invention, in the soundproofing member of the first invention or the second invention , the second soundproofing part is embedded and integrated with the first soundproofing part forming the outer shape of the soundproofing member. In the present invention, the first soundproofing part made of foamed resin forming the outer shape of the soundproofing member makes it possible to perform soundproofing against high-frequency sounds over a wider range. By embedding and integrating the highly rigid second soundproofing part into the first soundproofing part, this second soundproofing part functions as a core material, making it possible to more appropriately reinforce the first soundproofing part. ing.

A method for manufacturing a soundproof member according to a fourth invention is a method for manufacturing a soundproof member according to any one of the first to third inventions. The molding device for molding the first soundproofing part includes a first mold, a second mold that can be closed to the first mold, and a cavity formed between the first mold and the second mold in the closed state. At the same time, a protrusion that can be inserted into the opening is provided at a portion of at least one of the first mold and the second mold that faces the cavity. Therefore, in the present invention, after the protrusion is inserted into the opening and the second soundproofing part is installed in one mold, the first mold and the second mold are closed together, and then the molding material of the first soundproofing part is placed in the cavity. It was decided to foam and harden it. In the present invention, the second soundproof section can be set in the molding device by a relatively simple operation of inserting the protrusion provided on the molding device into the opening of the second soundproofing section. When forming the first soundproofing part, the protrusion inserted into the opening plays the role of a stopper, so the molding material of the first soundproofing part unintentionally flows into the hollow structure of the second soundproofing part. This situation can be avoided as much as possible.

Furthermore, in the method for manufacturing a soundproofing member according to the fourth aspect of the invention, prior to molding the first soundproofing part, the lid part is formed using an integral hinge part provided on one edge that forms a part of the outer edge of the second soundproofing part as a starting point. When the hollow structure is bent back and the hollow structure is closed, it is latched to the second soundproofing part via a latch structure provided on the outer edge portion of the second soundproofing part opposite to one edge . In the present invention, by forming the lid part with the second soundproofing part, the number of parts of the soundproofing member can be reduced, and the structure contributes to simplifying the structure. When molding the first soundproofing part, by folding back the lid in advance to close the hollow structure, there is no possibility that the molding material of the first soundproofing part will unintentionally flow into the hollow structure of the second soundproofing part. The situation can be avoided more reliably.

According to the first aspect of the present invention, soundproofing against a wide range of frequencies can be achieved while ensuring the rigidity of the soundproofing member. Further, according to the first invention, it is possible to make the structure of the soundproofing member as simple as possible while making it possible to soundproof a wide range of frequencies. Further, according to the second aspect of the present invention, soundproofing against a wide range of frequencies can be achieved while ensuring the rigidity and lightness of the soundproofing member. Moreover, according to the third invention, it is possible to more appropriately ensure the rigidity of the soundproofing member and to more appropriately soundproof a wide range of frequencies. Further, according to the fourth invention, it is possible to manufacture a soundproofing member capable of soundproofing a wide range of frequencies while ensuring its rigidity. According to the fourth invention, it is possible to more appropriately manufacture a soundproofing member having a relatively simple structure.

FIG. 2 is a schematic side view of the vehicle. FIG. 2 is a schematic cross-sectional view of the front part of the vehicle. It is a schematic sectional view of a soundproof member. It is a schematic perspective view of a second soundproof part. FIG. 3 is a schematic enlarged sectional view of a soundproofing member. FIG. 2 is a schematic perspective view of a soundproof member showing a latch structure. FIG. 2 is a schematic diagram of a Helmholtz sound absorber. It is a schematic sectional view showing a molding die for pulp molding. It is a schematic sectional view of each member showing the first half of the manufacturing process of the second soundproofing part. It is a schematic sectional view of each member showing the latter half of the manufacturing process of the second soundproofing part. FIG. 2 is a schematic cross-sectional view of a mold for pulp molding and a second soundproofing part. It is a schematic sectional view of each member showing the manufacturing process of the first soundproofing part. It is a schematic sectional view of the second soundproof part when closing a lid part. FIG. 3 is a schematic cross-sectional view of a soundproofing member according to a second embodiment. FIG. 7 is a schematic cross-sectional view of a soundproofing member according to a third embodiment. 3 is a graph showing the relationship between sound absorption coefficient and frequency of the soundproofing member of Example 1. FIG. It is a graph showing the relationship between the sound absorption coefficient and frequency of each first soundproofing part. 3 is a graph showing the relationship between the sound absorption coefficient and frequency of each second soundproofing part and the soundproofing member of Comparative Example 1. It is a graph which shows the relationship between the sound absorption coefficient and frequency of each other second soundproof part.

Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS. 1 to 19. For convenience, arrows indicating the longitudinal, vertical, and lateral directions of the vehicle are appropriately illustrated in each figure. In the vehicle 2 shown in FIG. 1, an engine room 5 is provided in front of the passenger compartment 4, and in this engine room 5, as shown in FIG. (For convenience, only the external shape of the engine is shown in FIG. 2). The engine compartment 5 has a rough outline formed by the vehicle body 3, and has a vertical wall-shaped dash panel 6 disposed at the rear to separate it from the vehicle compartment 4, and is further covered on the upper side by a hood panel 7. It is being said. Further, a pair of left and right front side members 8 forming the frame of the vehicle 2 are arranged in the lower part of the engine room 5. Each of these front side members 8 is a columnar member that extends in the front-rear direction while being arranged on the left and right sides of the engine EN, and at the rear end position of the engine room 5, the rear side members 8 are arranged so that the rear side is lowered along the dash panel 6. It is sloping.

[Soundproof member of Embodiment 1]
The soundproofing member 10 can be installed at an appropriate position facing the inside of the engine room 5 shown in FIG. 2, and can be installed, for example, on the front of the dash panel 6 (in FIG. The installed soundproofing member 10 is shown by a solid line, and the symbol (10) corresponding to the position where other soundproofing members can be installed is attached. Referring to FIG. 3, this soundproofing member 10 is used as an interior material for the engine room 5, and includes a first soundproofing part 11 and a second soundproofing part 12, which will be described later. In the soundproofing member 10, each of the soundproofing parts 11 and 12 enables soundproofing (sound absorption or sound insulation) against a wide range of frequencies, but this type of soundproofing member 10 is designed to be used as an interior material. It is desirable that the material has appropriate rigidity. Therefore, in this embodiment, with the configuration described later, it is possible to ensure the rigidity of the soundproofing member 10 while at the same time making soundproofing against a wide range of frequencies possible. Below, each structure and manufacturing method will be explained in detail using the soundproofing member 10 attached to the dash panel 6 as an example.

[First soundproofing section]
The first soundproofing part 11 shown in FIG. 3 is a part suitable for absorbing high-frequency sounds, and is made of foamed resin with an open cell structure. Here, "suitable for high frequency sound" means that the peak of the sound absorption coefficient measured by the normal incidence method is typically a high frequency peak of 1000 Hz or more, and this sound absorption coefficient is compliant with "JIS A 1405". (The sound absorption coefficient of the second soundproofing part 12, which will be described later, can also be measured using the same procedure.) The first soundproofing part 11 is formed into a vertical plate shape so as to form the outer shape of the soundproofing member 10, and its vertical and horizontal dimensions (area) are such that it can cover an appropriate position on the front surface of the dash panel 6. It is set. For example, the first soundproofing part 11 of this embodiment has a size that can generally cover the front surface of the dash panel 6, and is suitable for soundproofing the sound propagated to the vehicle interior 4 side through the dashpanel 6.

[Material of the first soundproofing part]
Here, the resin that is the material of the first soundproofing part 11 is a foamed resin (including a foamed elastomer) with an open cell structure, and can be integrally molded with the second soundproofing part 12 described later (the first soundproofing part 11 The formation method will be described later). Examples of this type of resin include polyurethane resin, polyester resin, polyether resin, melamine resin, mixed resins of these resins, and various foamed resins such as elastomers. If necessary, recycled foamed resin such as chip urethane may be mixed. You can also do it. The density of the resin that is the material of the first soundproofing part 11 can generally be set depending on the frequency of the sound to be absorbed, and is not particularly limited as long as it has the desired soundproofing properties. For example, when polyurethane resin is used as a material for soundproofing of sounds of 1000 Hz or higher, the density of the resin can be set in the range of 0.01 g/cm ³ to 0.4 g/cm ³ . Here, if the density of the polyurethane resin is less than 0.01 g/cm ³ , it becomes difficult to ensure the rigidity of the first soundproofing part 11, and its usage tends to be limited. Furthermore, if the density of the polyurethane resin exceeds 0.4 g/cm ³ , it may be difficult to foam and cure the resin to have an open cell structure, and there is a risk that desired sound absorption properties may not be obtained. By using polyurethane resin with a density of 0.02g/cm ³ to 0.25g/cm ³ as the material for the first soundproofing part 11, both sound absorption and rigidity of the first soundproofing part 11 are appropriately ensured. be able to.

In addition, the first soundproofing part 11 has an appropriate average thickness dimension T1 (the front and back dimension in FIG. 3) from the viewpoint of ensuring rigidity, and a second soundproofing part 12, which will be described later, is buried inside the first soundproofing part 11. It is integrated. Here, the average thickness dimension T1 of the first soundproofing part 11 can be set in consideration of the density of the material, the installation space, and the like. For example, when polyurethane resin with a density of 0.1 g/cm ³ is used as the material, the average thickness dimension T1 of the first soundproofing part 11 can be set to 5 mm or more. In addition, when the average thickness dimension T1 of the first soundproofing part 11 is less than 5 mm, it becomes difficult to obtain the desired sound absorbing property, and there is a possibility that its usage may be limited from the viewpoint of rigidity. Although the upper limit of the average thickness dimension T1 of the first soundproofing part 11 is not particularly limited, the larger the average thickness dimension T1 of the first soundproofing part 11, the higher the sound absorption coefficient on the high frequency side of the soundproofing member 10 can be. It is. When the soundproofing member 10 is used as an interior component installed in the engine room 5, it is desirable to set the average thickness T1 of the first soundproofing part 11 to 50 mm or less in consideration of the installation space. By setting the average thickness dimension T1 of the first soundproofing part 11 in the range of 10 mm to 40 mm, it is possible to obtain a configuration that takes up as little installation space as possible while ensuring desired rigidity and sound absorption properties.

[Second soundproofing section]
The second soundproofing part 12 shown in FIGS. 3 to 5 is a part suitable for soundproofing from sounds of a different frequency from that of the first soundproofing part 11. That is, the second soundproofing member 12 is equipped with a convex portion 15 having a hollow structure, which will be described later, so that it can perform soundproofing using the Helmholtz resonance principle, for example, to prevent low frequency sounds (less than 1000 Hz in this embodiment). suitable for soundproofing. This second soundproofing part 12 is a plate-shaped member with dimensions that fit within the first soundproofing part 11, and in this embodiment, the dimensions are approximately the same as those of the first soundproofing part 11 in a plan view seen from the front. (area). The second soundproofing section 12 includes a bottom wall section 14, a plurality of convex sections 15, an integral hinge section 40, a lid section 41, and a latch structure 44. Here, the bottom wall portion 14 is a vertical plate-shaped portion forming the outer shape of the second soundproofing portion 12, and is disposed relatively rearward when installed on the dash panel 6. In the second soundproofing portion 12, a plurality of convex portions 15, which will be described later, are formed in rows vertically and horizontally in plan view, and the bottom wall portion 14 is provided so as to fill in the spaces between the convex portions 15.

[Convex part (hollow structure)]
In the second soundproofing part 12, a plurality of convex parts 15 protrude from the bottom wall part 14 toward the engine room 5 side, as shown in FIGS. 3 and 5. Here, since each of the convex parts 15 has generally the same basic configuration, the details will be explained below using one convex part 15 as an example. Referring to FIGS. 4 and 5, the convex portion 15 is a generally quadrangular truncated pyramid-shaped portion having a hollow structure, and includes a ceiling wall portion 20, four side wall portions 21 to 24 forming a peripheral surface, and a portion described later. It has a communication section 30 of. Here, the ceiling wall portion 20 is a generally rectangular plate-shaped portion with the apex side disposed on the side of the engine room 5, and its four surfaces gradually slope gently toward the bottom side, and each of the side walls described below It is connected to sections 21-24. Further, in the convex portion 15, the bottom wall portion 14 is not disposed behind the ceiling wall portion 20, so that the convex portion 15 is open, and is closed by a lid portion 41, which will be described later.

[Side wall]
The four side walls (lower wall 21, upper wall 22, right wall 23, left wall 24) shown in FIG. be. In the convex portion 15, the paired side wall portions are arranged so as to have a generally hat cross-sectional shape, thereby increasing structural strength. That is, the lower wall portion 21 forming the lower surface of the convex portion 15 and the upper side wall portion 22 forming the upper surface are inclined in a direction that gradually separates from each other as they go from the ceiling wall portion 20 to the bottom wall portion 14. Further, the right side wall 23 forming the right side of the convex portion 15 and the left side wall 24 forming the left side are also inclined in a direction gradually moving away from each other as they go from the ceiling wall 20 to the bottom wall 14. In this way, by making the protrusion 15 have a hat cross-sectional shape and increasing the strength, it is possible to appropriately maintain the shape of the protrusion 15 even when a load is applied from the engine room 5 side. Therefore, the soundproofing member 10 can be used as a reinforcing member for a vehicle, a raising member, etc. by maintaining an appropriate thickness by the convex portions 15, and has an easy-to-use structure. Furthermore, by increasing the thickness of the soundproofing member 10 by the convex portions 15, the mass (amount used) of the first soundproofing portion 11 can be reduced, resulting in a configuration that contributes to cost reduction and weight reduction.

[Communication section (opening)]
Each of the convex portions 15 shown in FIGS. 3 to 5 is provided with a communication portion 30 that communicates between the inside and outside of the convex portion. Since each of these communicating portions 30 has generally the same configuration, the details will be explained below using one convex portion 15 as an example. The communication portion 30 shown in FIG. 5 is a cylindrical portion that protrudes from approximately the center of the ceiling wall portion 20, and has a predetermined length dimension L1 in the tube length direction (front-back direction in FIG. 5). . A passage part 32 is provided inside the communication part 30, and this passage part 32 has an opening area S that allows gas to pass through, and extends along the axial direction of the communication part 30 to the ceiling wall part 20. It penetrates in the thickness direction (front-to-back direction in FIG. 5). The passage portion 32 has a first opening portion OP1 that opens into the convex portion 15 at the rear end of the communication portion 30, and a second opening portion OP2 that opens at the front end (one end) of the communication portion 30. Here, the second opening OP2 corresponds to the opening of the present invention. In the convex portion 15, it is possible to set the frequency of the sound to be absorbed by adjusting the aperture ratio of the passage portion 32 based on the Helmholtz resonance principle described later. Note that a plurality of communicating portions 30 (passage portions 32) can be provided in the ceiling wall portion 20 or a single one, and when a single communicating portion 30 is formed, the opening area S of the passage portion 32 and the area of the ceiling wall portion 20 are The aperture ratio can be defined as a percentage. Further, when a plurality of communication sections 30 are provided, the aperture ratio can be defined by the ratio of the total opening area of all the passage sections 32 to the area of the ceiling wall section 20.

[Performance of the second soundproofing section (Helmholtz resonance principle)]
Here, the Helmholtz resonance principle will be explained based on the Helmholtz resonator 50 shown in FIG. can. That is, in the Helmholtz resonator 50, the internal volume of the internal space 51 of the resonator is V (cm ³ ), the length of the communication part 52 of the resonator is L (cm), and the radius of the opening OP of the communication part 52 of the resonator is a (cm ² ) and the speed of sound is c (cm/s), the frequency f (Hz) of the sound incident on the communication portion 52 of the resonator can be determined by the following equation (1). The Helmholtz resonator 50 can absorb sound at a frequency f, and this frequency f is inversely proportional to the volume V of the internal space 51 of the resonator and the square root of the length L of the communicating portion 52. is directly proportional to the square root of the aperture area πa ² (aperture ratio).
Formula 1: f=(c/2π)×√(πa ² /(V(L×0.6a)))

The volume within the convex portion 15 as a hollow structure shown in FIG. 5 can be appropriately set depending on the frequency of sound to be soundproofed. Considering that the first soundproofing section 11 described above is suitable for soundproofing high frequency sounds (1000Hz or more), the second soundproofing section 12 is designed to prevent low frequency sounds (less than 1000Hz) different from the first soundproofing section 11. Adjust to soundproof. According to the Helmholtz resonance principle described above, the convex portion 15 having a large volume can relatively attenuate low frequency sound, and the convex portion 15 having a small volume can relatively attenuate high frequency sound. Therefore, in this embodiment, by increasing the volume of each convex portion 15, etc., it is possible to attenuate low frequency sound and make it possible to absorb sound. Furthermore, according to the Helmholtz resonance principle, by increasing the length of the communicating portion 30 and decreasing the aperture ratio, the frequency f (Hz) of the incident sound gradually decreases. For this reason, when the second soundproofing section 12 efficiently absorbs relatively low-frequency sounds, it is desirable to increase the length L1 of the communication section 30 and to decrease the aperture ratio.

[Relationship between the shape of the convex part (ceiling wall part) and the first soundproofing part]
Here, in the soundproofing member 10, it is possible to balance the sound absorption coefficient of the second soundproofing part 12 and the sound absorption coefficient of the first soundproofing part 11 by the shape of the ceiling wall part 20 shown in FIG. That is, by adjusting the average thickness dimension T11 of the first soundproofing part 11 on the ceiling wall part 20 by the shape of the ceiling wall part 20, the soundproofing characteristics of the first soundproofing part 11 can be adjusted. For example, in this embodiment, by making the rising angle θ of the ceiling wall 20 with respect to the bottom wall 14 smaller than that of each side wall 21, etc., the thickness of the first soundproofing part 11 becomes gradually smaller toward the communication part 30. It is set as follows. In this way, by avoiding as much as possible a situation where the thickness of the first soundproofing part 11 suddenly becomes thinner on the ceiling wall part 20 and the soundproofing characteristics change, the sound absorption coefficient of the first soundproofing part 11 in the high frequency range is appropriately ensured. be able to. Note that if it is desired to relatively increase the sound absorption coefficient of the second soundproofing part 12, the above-mentioned average thickness dimension T11 can be made relatively small by forming the convex part 15 in the shape of a square prism and making the ceiling wall part 20 higher. It is desirable to keep it.

[Integral hinge part, lid part]
The lid part 41 shown in FIGS. 3 and 6 is a part that can close the bottom side of the rear end (other end) of each of the above-mentioned convex parts 15, and in this embodiment, it is integrally attached to the second soundproof part 12. It is provided. That is, a groove-shaped integral hinge part 40 extending in the left-right direction is provided at the lower edge of the bottom wall part 14, and a plate-shaped lid part 41 is integrally provided outside the integral hinge part 40. ing. This lid part 41 is a generally flat plate-shaped part having a size (area) that can cover all the convex parts 15 and the bottom wall part 14 of the second soundproof part 12, and the peripheral part except the lower edge is A flange portion 42 projecting forward is provided. Further, referring to FIG. 13, the lid portion 41 can be folded upward from the state of extending downward from the lower edge of the bottom wall portion 14 using the integral hinge portion 40 as a base point. In this embodiment, the bottom side of each convex portion 15 of the second soundproofing portion 12 is closed by the lid portion 41 that is folded back upward. Moreover, in the lid part 41 in the closed state, the flange part 42 shown in FIG. 6 is arranged so as to surround the bottom wall part 14 that forms the outer shape of the second soundproof part 12.

[Latch structure]
The lid portion 41 is latched to the upper edge side of the bottom wall portion 14 via a latch structure 44 shown in FIGS. It is composed of a locking protrusion 46 and a locking hole 47 of the lid portion 41. That is, the locking wall portion 45 is a standing wall-shaped portion that stands up forward from the upper edge of the bottom wall portion 14, and the locking protrusion 46 is a protrusion that projects upward from the front portion of the upper surface of the locking wall portion 45. be. Further, the locking hole portion 47 is a through hole provided in the flange portion 42 on the upper edge side of the lid portion 41, and is formed at a position through which the locking protrusion 46 can be inserted in the closed state. In this embodiment, after the lid portion 41 is folded back to close each convex portion 15, the locking protrusion 46 of the bottom wall portion 14 is inserted into the locking hole portion 47 provided on the upper edge side of the lid portion 41. do. By doing so, the folded lid portion 41 is locked to the bottom wall portion 14 via the latch structure 44, and movement of the lid portion 41 in an unintended opening direction can be avoided as much as possible.

[Material of the second soundproofing part]
Here, as a material for the second soundproofing part 12 shown in FIG. 5, a material with higher rigidity than the first soundproofing part 11 is used, and it is preferable to use a material suitable for sound absorption and sound insulation. Examples of this type of material include fiber laminates made of cellulose fibers, animal fibers, mineral fibers, and inorganic fibers, metal plates of the same or different type as the vehicle body, various solid resins (including elastomers), and rubber. An example is plate material. Among these, the fiber laminate is suitable for use as a material for the second soundproofing part 12 because it has excellent sound absorption and sound insulation performance and is lighter than metal or resin. In this embodiment, as the material of the second soundproofing part 12, a material in which a plurality of cellulose fibers are integrated in a laminated state is used. Various types of cellulose fibers can be used as this type of cellulose fiber, such as plant fibers (natural fibers), regenerated fibers, refined fibers, and semi-synthetic fibers. Cellulose fibers obtained from waste paper pulp) can be suitably used.

In addition, in this embodiment, the average thickness dimension T2 of the second soundproofing part 12 shown in FIG. Not limited. For example, when the second soundproofing section 12 is used as an interior material for a vehicle, the average thickness dimension T2 of the second soundproofing section 12 is typically 1.5 mm to 1.5 mm, considering the average thickness dimension T1 of the first soundproofing section 11, etc. It can be set in the range of 15 mm, and from the viewpoint of ensuring lightness, it is desirable to set it in the range of 2.0 mm to 8.0 mm. In addition, when the length dimension L1 of the communication part 30 is obtained by the average thickness dimension T2 of the ceiling wall part 20, the average thickness dimension T2 of the part of the ceiling wall part 20 where the communication part 30 is formed is different from the other wall parts. Can be set independently. That is, the above-mentioned average thickness dimension T2 of the ceiling wall portion 20 portion can be appropriately set according to the performance of the communication section 30, and may deviate from the range of the above-mentioned average thickness dimension T2.

[Rigidity of second soundproofing section (Young's modulus)]
As described above, the second soundproofing part 12 has better rigidity than the first soundproofing part 11, and the rigidity of each of the soundproofing parts 11 and 12 can be roughly defined by Young's modulus. Here, Young's modulus can be measured by a tensile test based on "JIS K 7113". The Young's modulus of the second soundproofing section 12 is set to be larger than the Young's modulus of the first soundproofing section 11, and is preferably 1.5 times or more the Young's modulus of the first soundproofing section 11. For example, it is assumed that a polyurethane resin is used as the material for the first soundproofing part 11, and a material in which cellulose fibers are integrated in a laminated state (pulp molded product described below) is used as the material for the second soundproofing part 12. The first soundproofing part 11 made of polyurethane resin has a density in the range of 0.01g/cm ³ to 0.4g/cm ³ as described above, and a Young's modulus thereof typically in the range of 0.001GPa to 0.1GPa. is within the range of Further, the second soundproofing part 12 made of a pulp molded body typically has a tightness (apparent specific gravity) corresponding to density in a range of 0.3 g/cm ³ to 0.4 g/cm ³ and a Young's modulus of , in the range of 0.2 GPa to 0.8 GPa. Therefore, the second soundproofing part 12 has a Young's modulus that is twice to 800 times that of the first soundproofing part 11, and has superior rigidity than the first soundproofing part 11.

[Formation method of second soundproofing part]
The method of forming the second soundproofing part 12 shown in FIGS. 3 to 5 can be set as appropriate depending on the material to be used, and in this embodiment, the second soundproofing part 12 is formed by pulp molding, which will be described later. There is. Referring to FIGS. 8 and 11, this molding die 60 for pulp molding includes a molding surface 61 forming the outer surface, a net material 62 disposed along the molding surface 61, and a molding surface 62 arranged along the molding surface 61. (In each figure, only one liquid suction part is designated by the reference numeral 63 for convenience). A plurality of convex portions 611 on which the convex portions 15 are to be formed are provided on the molding surface 61 at appropriate intervals, and between adjacent convex portions 611 there are flat portions for forming the bottom wall portion 14. It is 612. Furthermore, the molding surface 61 is provided with portions at appropriate positions where each component of the second soundproofing portion 12 (lid portion, latch structure, etc.) can be formed. For example, the molding surface 61 is provided with a groove-shaped recess 613 for forming the integral hinge portion 40, and a flat surface 614 for forming the lid portion 41 is provided on the outside of the recess 613. It is being The net material 62 is a net-like member that allows liquid to pass through but does not substantially allow cellulose fibers to pass through, and is installed so as to cover almost the entire surface of the molding surface 61. Further, the liquid suction part 63 is a part for sucking liquid into the mold 60 as described later, and a plurality of openings of the liquid suction part 63 can be provided at appropriate positions on the molding surface 61. The liquid suction unit 63 includes a pump (not shown) and a flow path (not shown) in the mold 60 that transfers the sucked liquid to a predetermined location.

Referring to FIG. 9, a mold 60 for pulp molding is immersed in a liquid stock solution 68 (details will be described later) containing cellulose fibers, and while sucking the stock solution from a liquid suction part 63, Cellulose fibers are laminated on the net material 62. For example, after the mold 60 is turned upside down and the molding surface 61 is immersed in the stock solution, the liquid of the stock solution is sucked from the liquid suction part 63 that opens in the molding surface 61. In this case, the cellulose fibers contained in the liquid cannot pass through the net material 62 that covers the outer surface of the mold 60, so that they are gradually stacked on the net material 62. After a desired amount of cellulosic fibers are laminated on the net material 62, the mold 60 is lifted from the stock solution, and the laminated cellulose fibers are dried and integrated. In this way, the rough outer shape of the second soundproofing part is formed of a material (12) in which cellulose fibers are integrated in a laminated state, as shown in FIG. Therefore, after removing the material (12) from the mold 60 and drying it, as shown in FIG. The soundproofing part 12 can be completed.

[Inner and outer surfaces of the second soundproofing section]
The second soundproofing part 12 shown in FIGS. 3 to 5 manufactured in this way is formed of a pulp molded body in which a plurality of cellulose fibers are laminated and integrated, and has appropriate strength and is relatively lightweight. It becomes. Further, according to pulp molding, as shown in FIGS. 5 and 11, the inner surface 12a of the second soundproofing part 12 disposed on the side of the net material 62 is relatively smooth because it is formed in contact with the net material 62. It is in a state of In contrast, the outer surface 12b of the second soundproofing section 12 has a larger uneven shape than the inner surface 12a due to a difference in the amount of laminated cellulose fibers. The outer surface 12b, which has a large uneven shape, has better diffusion performance for reflected sound than the inner surface 12a on the opposite side, so that echoes are repeated in a specific direction and the sound (reverberant sound, etc.) is amplified. The situation can be avoided as much as possible.

[Still solution (pulp)]
Here, the method for forming the stock solution 68 shown in FIG. 9 is not particularly limited, but as a general method, a predetermined amount (for example, an amount with a solid content of 0.5% by weight or more) of pulp is poured into water, and then An example of this method is to stir the mixture until it becomes a slurry. As the pulp, chemical pulp, mechanical pulp, waste paper pulp, and non-wood pulp can be used singly or in combination of two or more kinds, and it is particularly desirable to use waste paper pulp from the viewpoint of recyclability. Examples of this type of waste paper pulp include disintegrated waste paper pulp, defibrated/deinked waste paper pulp, and defibrated/deinked/bleached waste paper pulp.The raw materials for this waste paper pulp include wood-free paper, medium-quality paper, low-grade paper, newspaper, and leaflets. It can be obtained from sorted or unsorted waste paper such as magazines. Chemical pulps include softwood unbleached kraft pulp (NUKP), hardwood unbleached kraft pulp (LUKP), softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood semi-bleached kraft pulp (NSBKP), and hardwood semi-bleached kraft pulp. Examples include bleached kraft pulp (LSBKP), softwood sulfite pulp, and hardwood sulfite pulp. Examples of mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermoground pulp (TGP), chemical ground pulp (CGP), and thermomechanical pulp (TMP). can. Examples of non-wood pulp include pulps made from non-wood fibers such as kenaf, hemp, and reed.

Additives that contribute to improving the performance of the second soundproofing section can be added to the stock solution 68 shown in FIG. 9 . These types of additives include sizing agents, paper strength enhancers such as dry paper strength agents and wet paper strength agents, PH adjusters, freeness improvers, antifoaming agents, bulking agents, retention agents, antibacterial agents, Examples include antifungal agents, fillers, and dyes. Among these, sizing agents that prevent water from penetrating and contribute to improved water resistance, dry paper strength agents that contribute to improving breaking strength (strength) in dry conditions, and wet paper strength agents that contribute to improved strength when wet. Preferably, at least one of the agents is added to the stock solution 68. Examples of sizing agents include rosin-based sizing agents, AKD-based sizing agents, alkenyl succinic anhydride (ASA)-based sizing agents, petroleum-based sizing agents, and neutral rosin sizing agents. Examples of dry paper strength agents include polyacrylamide polymers such as anionic polyacrylamide resins, polyvinyl alcohol polymers, cationic starches, various modified starches, urea/formalin resins, and melamine/formalin resins. Further, as a wet paper strength agent, a polyamide polyamine epichlorohydrin resin (or a modified product thereof) can be exemplified. Note that the amount of each additive added to the stock solution 68 is not particularly limited as long as desired performance can be imparted to the second soundproofing section. For example, the sizing agent can be added in an amount of 0.5% to 5% by weight, and preferably 1.0% by weight or more. The dry paper strength agent can be added in an amount of 0.5% to 5% by weight, and preferably 3.0% by weight or more. Further, the wet paper strength agent can be added in a range of 2% by weight to 15% by weight, and preferably 4.0% by weight or more.

[Formation of the first soundproofing part (molding device, protrusion)]
Next, the first soundproofing part 11 shown in FIG. 3 is molded using the molding apparatus 70 shown in FIG. 12 and integrated into the second soundproofing part 12. As shown in FIG. 12, the molding device 70 has a first mold 71 and a second mold 72 that can be closed to the first mold 71. A cavity 73 is formed to serve as a molding space for the soundproof section. A plurality of protrusions 74 are provided on a portion (inner surface) of the first mold 71 facing the cavity. Each of these projections 74 is a pin-shaped portion with a diameter that follows the inner diameter of the second opening OP2 of the second soundproofing portion 12, and is arranged at a position into which the corresponding second opening OP2 can be inserted. There is.

Therefore, in this embodiment, the second soundproofing part 12 can be set in the molding device 70 by inserting each protrusion 74 of the first mold 71 into the corresponding second opening OP2 of the second soundproofing part 12. . Also, before and after the above-mentioned work (prior to the molding of the first soundproofing part), as shown in FIG. It is closed and further latched to the bottom wall portion 14 via the latch structure 44. After setting the second soundproofing part 12 as shown in FIG. 12 in this way, the first mold 71 and the second mold 72 are closed, and the molding material 11X of the first soundproofing part 11 is foamed and hardened in the cavity 73. let In this way, the soundproofing member 10 can be manufactured by molding the first soundproofing part 11 and integrating it with the second soundproofing part 12. At this time, since a relatively large uneven shape is formed on the outer surface 12b of the second soundproofing section 12, this unevenness functions as an anchor, thereby stably integrating the first soundproofing section 11. You can leave it there. When the first soundproofing part 11 is molded, the protrusion 74 inserted into the opening plays the role of a plug, so the molding material 11X of the first soundproofing part 11 is inside each convex part 15 (hollow structure). It is possible to avoid as much as possible the situation of unintentional inflow. Furthermore, when molding the first soundproofing part 11, by folding back the lid part 41 and closing each convex part 15 in advance, the molding material 11X of the first soundproofing part 11 is spread inside each convexity 15 (hollow structure). This makes it possible to more reliably avoid situations such as unintentional inflow.

[Soundproofing properties of soundproofing materials]
In the vehicle 2 shown in FIGS. 1 and 2, a soundproof member 10 is disposed at an appropriate position within the engine room 5 for the purpose of absorbing and insulating sounds emitted within the engine room 5. The soundproofing member 10 shown in FIG. 3 has a structure in which the first soundproofing part 11 and the second soundproofing part 12 absorb sounds of a wide range of frequencies. In this type of configuration, it is desirable to be able to soundproof a wide range of frequencies while ensuring the rigidity of the soundproofing member 10 as described above.

Therefore, as shown in FIG. 3, the soundproofing member 10 of this embodiment includes a first soundproofing part 11 made of foamed resin with an open cell structure, and a convex part 15 (hollow) that is more rigid than the first soundproofing part 11. It is an integrally molded product with the second soundproofing part 12 having a structure). The first soundproofing part 11 is integrated around the second soundproofing part 12 with the second opening OP2 of the convex part 15 exposed. That is, the soundproofing member 10 of this embodiment is an integrally molded product of the first soundproofing part 11 and the second soundproofing part 12, and when the first soundproofing part 11 is arranged around the second soundproofing part 12, It is strongly integrated. Therefore, the first soundproofing section 11 is able to perform soundproofing against high-frequency sounds while being reinforced by the second soundproofing section 12. Further, in this embodiment, since the second soundproofing part 12 has the convex part 15, sound of a different frequency (low frequency sound in this embodiment) from the first soundproofing part 11 is generated using the Helmholtz resonance principle. ) is suitable for soundproofing. That is, since the second opening OP2 of the convex portion 15 is exposed from the first soundproofing portion 11, it is possible to attenuate the sound incident on the second opening OP2 within the convex portion 15 and absorb the sound. It has become. Therefore, the soundproofing properties of the engine room 5 by the soundproofing member 10 of this embodiment will be specifically explained below.

[Soundproofing for sounds generated in the engine room (sound absorption and insulation)]
In the soundproofing member 10 shown in FIG. 3, the first soundproofing part 11 can perform soundproofing against high frequency sounds (SD1) generated within the engine room 5, and can typically perform soundproofing against sounds of 1000 Hz or higher. In this embodiment, the first soundproofing part 11 forms the outer shape of the soundproofing member 10 and covers almost the entire front surface of the dash panel 6. Therefore, the first soundproofing section 11 can insulate the high-frequency sound (SD1) generated within the engine room 5 over a wide range, and the situation in which the sound is excessively transmitted to the passenger compartment 4 can be avoided as much as possible. Further, in the soundproofing member 10, the second soundproofing part 12 can perform soundproofing against low frequency sounds (SD2) generated in the engine room 5, and can typically perform soundproofing against sounds of 100 Hz or more and less than 1000 Hz. That is, in the second soundproofing part 12, the low frequency sound (SD2) propagated into each convex part 15 through each second opening OP2 can be attenuated and absorbed using the Helmholtz resonance principle. In this embodiment, the convex portions 15 forming the hollow structure of the second soundproofing portion 12 are arranged in a well-balanced manner over substantially the entire surface of the soundproofing member 10 when viewed from above. Further, in the second soundproofing part 12, the bottom side of each convex part 15 is closed with a lid part 41 which is relatively hard and has excellent soundproofing properties. Therefore, the second soundproofing part 12 can soundproof the low-frequency sound (SD2) generated in the engine room 5 over a wide range, and avoid the situation where the sound is excessively transmitted to the passenger compartment 4 as much as possible. be able to.

As explained above, the soundproofing member 10 of this embodiment is an integrally molded product of the first soundproofing part 11 and the second soundproofing part 12, and the first soundproofing part 11 is arranged around the second soundproofing part 12. It is relatively strongly integrated. Therefore, the first soundproofing section 11 is able to perform soundproofing against high-frequency sounds while being reinforced by the second soundproofing section 12. Moreover, in this embodiment, since the second soundproofing part 12 has the convex part 15 (hollow structure), the sound of a different frequency (for example, low frequency) from the first soundproofing part 11 is generated using the Helmholtz resonance principle. The configuration is suitable for soundproofing. In other words, since the second opening OP2 of the convex portion 15 (hollow structure) is exposed from the first soundproofing portion 11, the sound incident on the second opening OP2 is attenuated within the convex portion 15 (hollow structure). This makes it possible to absorb sound. Therefore, according to the present embodiment, soundproofing against a wide range of frequencies can be achieved while ensuring the rigidity of the soundproofing member 10.

Furthermore, the second soundproofing part 12 of the present embodiment is made of cellulose fiber that has excellent soundproofing properties and is lighter than resin or metal, so it has a configuration that contributes to improving the performance of the soundproofing member 10. . Furthermore, in this embodiment, by integrally forming the lid part 41 that closes the convex part 15 (hollow structure) with the second soundproofing part 12, the number of parts of the soundproofing member 10 can be reduced, and the structure can be improved. The configuration contributes to simplification. Furthermore, in this embodiment, the first soundproofing part 11 made of foamed resin and forming the outer shape of the soundproofing member 10 makes it possible to perform soundproofing against high-frequency sounds over a wider range. By embedding and integrating the highly rigid second soundproofing part 12 into the first soundproofing part 11, the second soundproofing part 12 functions as a core material and more appropriately reinforces the first soundproofing part 11. is possible.

Further, in the manufacturing method of the present embodiment, the second soundproofing part 12 is formed in the molding apparatus by a relatively simple operation of inserting the protrusion 74 provided in the molding apparatus 70 into the second opening OP2 of the second soundproofing part 12. It can be set to 70. When the first soundproofing part 11 is molded, the protrusion 74 inserted into the second opening OP2 plays the role of a plug, so that the molding material of the first soundproofing part 11 is applied to the convexity of the second soundproofing part 12. It is possible to avoid as much as possible a situation where the liquid flows into the portion 15 unintentionally. Moreover, in this embodiment, by forming the lid part 41 with the second soundproofing part 12, the number of parts of the soundproofing member 10 can be reduced, and the structure contributes to the simplification of the structure. When molding the first soundproofing part 11, the lid part 41 is folded back in advance to close the convex part 15, so that the molding material of the first soundproofing part 11 is transferred into the convexity 15 of the second soundproofing part 12. Situations such as unintentional inflow can be more reliably avoided.

[Soundproofing member of Embodiment 2]
In the soundproofing member 10A of the second embodiment shown in FIG. 14, components having substantially the same basic configuration as the soundproofing member of the first embodiment are given corresponding symbols, and detailed explanations thereof will be omitted. The soundproofing member 10A of the second embodiment has a first soundproofing part 11 and a second soundproofing part 12 having almost the same basic configuration as the first embodiment, but the lid part 41A is different from the first soundproofing part 11. This differs from the first embodiment in that it is integrally formed. That is, in this embodiment, the lid part 41A is omitted from the second soundproofing part 12, and a groove-shaped integral hinge part 40A and a plate-shaped lid part 41A are provided at the lower edge of the first soundproofing part 11. They are provided integrally in this order. The lid portion 41A can be folded back upward from the integral hinge portion 40A from a state extending downward from the lower edge of the first soundproofing portion 11. In this embodiment, the bottom side of each convex part 15 of the second soundproofing part 12 is closed by folding the lid part 41A upward and then integrating it with the first soundproofing part 11 by adhesion or fusion. The state can be set as follows. Note that the lid portion 41A and the integral hinge portion 40A can be molded simultaneously with the first soundproofing portion 11 by changing the mold shape of the molding device 70 shown in FIG. Further, it is also possible to mold the lid portion 41A shown in FIG. 14 as a separate body and then attach it to the first soundproofing portion 11 afterwards.

[Soundproofing member of Embodiment 3]
In the soundproofing member 10B of the third embodiment shown in FIG. 15, components having substantially the same basic configuration as the soundproofing member of the first embodiment are given corresponding symbols, and detailed description thereof will be omitted. The soundproofing member 10B of Embodiment 3 has a first soundproofing part 11 and a second soundproofing part 12 having almost the same basic configuration as Embodiment 1, but the lid part 41B is formed in a hollow box shape. This embodiment is different from the first embodiment in that the second embodiment is different from the first embodiment. This lid part 41B is a hollow box-shaped part for closing the bottom side of each of the above-mentioned convex parts 15, and is integrally provided on the lower edge of the bottom wall part 14 via an integral hinge part 40B. ing. The lid portion 41B includes a bottom plate portion 411 disposed facing each convex portion 15, and a circumferential plate portion 412 bent forward from the bottom plate portion 411. It is formed around the entire circumference of the portion 411. The upper edge side of the circumferential plate portion 412 extends relatively forward, and a locking hole portion 47 that is a part of the latch structure 44 is formed therein. Note that the method of forming the lid part 41B is not particularly limited, but for example, it can be integrally formed with the second soundproofing part 12 by the above-mentioned pulp molding, or the lid part 41B formed as a separate part can be attached to the second soundproofing part 12 afterwards. is also possible.

In the soundproofing member 10B of this embodiment, a closed lid portion 41B is disposed behind each convex portion 15. At this time, the bottom plate part 411 is arranged at a distance behind each convex part 15, and the peripheral plate part 412 is applied to the rear of the bottom wall part 14, so that the area surrounded by the bottom plate part 411 and the peripheral plate part 412 is A back space 80 is formed. This back space portion 80 can function as an air layer that enables sound attenuation, and the volume of the back space portion 80 can be approximately defined by the distance L2 between the convex portion 15 and the bottom plate portion 411. In this way, in the second soundproofing part 12 of this embodiment, the volume of the convex part 15 becomes larger in the back space part 80, thereby making it possible to further attenuate low-frequency sound.

[Test example]
The present embodiment will be described below based on test examples, but the present invention is not limited to the test examples. Here, FIG. 16 is a graph showing the relationship between the sound absorption coefficient and frequency of the soundproofing member of Example 1. Further, FIG. 17 is a graph showing the relationship between sound absorption coefficient and frequency of first soundproof parts (1) to (3), which will be described later. Further, FIG. 18 is a graph showing the relationship between the sound absorption coefficient and frequency of the second soundproofing parts (1) to (7) and the soundproofing member of Comparative Example 1, which will be described later. FIG. 19 is a graph showing the relationship between sound absorption coefficient and frequency of second soundproofing parts (1), (8) to (10), which will be described later.

[Example 1]
As the soundproofing member of Example 1, a plate-shaped soundproofing member shown in FIG. 3 was manufactured. At this time, using the molding apparatus shown in FIG. 12, the first soundproofing part (1) made of polyurethane resin was molded and integrated into the second soundproofing part (1) to be described later. As a molding material for the polyurethane resin, Formlite NE series (trade name) manufactured by BASFINOAc Polyurethane Co., Ltd. was used. The first soundproofing part (1) had an average thickness of 30 mm, a density of 0.1 g/cm ³ , and a Young's modulus of 0.025 GPa. Further, the second soundproofing part (1) was manufactured through the steps shown in FIGS. 9 to 11, using a mold for pulp molding shown in FIG. 8. The stock solution used was a slurry made by adding a predetermined amount of waste paper pulp to water. The shape shown in FIG. 3 was adopted as the shape of the second soundproofing part, and a plurality of convex parts were provided at approximately equal intervals. Further, the basis weight of each convex portion was approximately 4 g, and the internal volume of each convex portion was 21.4 cm ³ . Further, one communication part was provided for each convex part, the length dimension of the communication part was set to 0.3 cm, and the opening dimension of the passage part was set to φ3 mm. The second soundproofing part (1) had an average thickness of 5 mm, a tightness of 0.3 g/cm ³ , and a Young's modulus of 0.2 GPa.

[Comparative example 1]
Further, as the soundproofing member of Comparative Example 1, a felt face material having an average thickness of 13 mm was used.

[Another example of the first soundproofing section]
In addition, the first soundproofing parts (2) and (3) are set to a different average thickness from the first soundproofing part (1) in order to see the change in sound absorption depending on the average thickness dimension, and the other configurations are the same as the first soundproofing part (1). Same as part (1). That is, in the first soundproofing part (2), the average thickness dimension was set to 10 mm, and in the second soundproofing part (3), the average thickness dimension was set to 30mm.

[Another example of the second soundproofing section]
In addition, in the second soundproofing parts (2) to (7), the number of communication parts (passage parts) was changed in order to see the change in sound absorption due to the aperture ratio, and the other configurations were the same as the second soundproofing part (1). And so. That is, in the second soundproofing part (2), two communicating parts are provided in each convex part, in the second soundproofing part (3), three communicating parts are provided in each convex part, and in the second soundproofing part (4), Each protrusion has four communication parts, the second soundproofing part (5) has five communication parts in each protrusion, and the second soundproofing part (6) has six communication parts in each protrusion. In the second soundproofing part (7), eight communicating parts were provided in each convex part.

Further, in the second soundproof parts (8) to (10), a back space part was formed on the bottom side of each convex part using the structure of the lid part of Embodiment 3. In the second soundproofing part (8), the distance between the convex part and the bottom plate part is set to 40 mm, and in the second soundproofing part (9), the distance between the convex part and the bottom plate part is set to 20mm. In part (10), the distance between the convex part and the bottom plate part was set to 10 mm.

[Sound absorption property test]
In the sound absorption property test, a normal incidence sound absorption coefficient measuring device (Nittobo Acoustic Engineering, WinZacMTX) was used, and the measurement conditions were set to 315 to 5000 Hz/φ28.6 mm. Then, the soundproofing member of Example 1 was placed on a measurement table with the ceiling wall side facing upward. In this state, sound was emitted from the upper side (corresponding to the engine room) of the soundproofing member of Example 1, and its sound absorption coefficient was measured. Further, the soundproofing member of Comparative Example 1 was placed on a measurement stand, and the sound absorption coefficient was measured under the same conditions as in Example 1. The sound absorption coefficients of the first soundproof parts (1) to (3) and the sound absorption coefficients of the second soundproof parts (1) to (10) were then measured under the above-mentioned conditions.

[Results and discussion]
Referring to FIG. 18, the soundproofing member of Comparative Example 1 has a sound absorption coefficient curve that is overall broad and does not have a peak in the low frequency region, and is not suitable for appropriately soundproofing a wide range of frequencies. I understand. In contrast, in the soundproofing member of Example 1 shown in FIG. 16, the sound absorption coefficient was significantly higher overall than that of Comparative Example 1, and a sound absorption coefficient curve with peaks near 400 Hz and 2700 Hz was obtained. . This result is considered to be because the first soundproofing part absorbed high frequency sounds around 2700 Hz, and the second soundproofing part absorbed low frequency sounds around 400Hz. The soundproofing member of Example 1 was found to have excellent rigidity because the first soundproofing part was integrated with the second soundproofing part without peeling, and the second soundproofing part made it difficult to bend. Ta. From this, it was easily inferred that in the soundproofing member of Example 1, it was possible to perform soundproofing against high-frequency sounds while the first soundproofing part was reinforced by the second soundproofing part. . From this, it has been found that the soundproofing member of Example 1 can provide soundproofing against a wide range of frequencies while ensuring the rigidity of the soundproofing member.

Moreover, the sound absorption coefficient curve of the sound insulation member of Example 1 shown in FIG. 16 is the sound absorption coefficient curve of the first sound insulation part (1) shown in FIG. 17, and the sound absorption coefficient curve of the second sound insulation part (1) shown in FIG. It was a curve that resembled a combination of From this, it was easily inferred that by appropriately combining the configuration of the first soundproofing part and the configuration of the second soundproofing part, a soundproofing member suitable for soundproofing a wide range of sounds could be formed. Referring to FIG. 17, sound absorption coefficient curves with peaks in the high frequency region (near 2000Hz to 4500Hz) were obtained for the first soundproofing parts (1) to (3), so all of them are suitable for soundproofing high frequency sounds. I found out that From the results of the first soundproofing parts (1) to (3), it was found that the peak of the sound absorption coefficient curve could be adjusted by adjusting the average thickness dimension.

Further, referring to FIG. 18, sound absorption coefficient curves having peaks in the low frequency region (near 400 Hz to 950 Hz) were obtained for the second soundproof parts (1) to (7), respectively. From the results of the second soundproofing parts (1) to (7), it was found that the peak of the sound absorption coefficient curve could be adjusted by increasing the number of communication parts and increasing the aperture ratio. Furthermore, from the above results, it can be easily inferred that by using a combination of convex portions having different numbers of communicating portions (aperture ratios), the peak of the sound absorption frequency can be broadened, and sound of a wider range of frequencies can be absorbed.

Furthermore, referring to FIG. 19, sound absorption coefficient curves having sharp peaks in the lower frequency range (near 180 Hz to 330 Hz) were obtained for the second soundproof parts (8) to (10), respectively. From this, by providing the back space in the lid as in Embodiment 3, the configuration becomes more suitable for soundproofing low-frequency sounds, and furthermore, it is possible to absorb more low-frequency sounds in proportion to the volume of the back space. I understand.

The soundproofing member of this embodiment is not limited to the embodiment described above, and may take various other embodiments. In this embodiment, the configuration (shape, size, installation position, number of installations, etc.) of the soundproofing member 10 is illustrated, but this is not intended to limit the configuration of the soundproofing member. For example, soundproofing materials can be used for a variety of purposes in addition to being used as interior materials for engine compartments. Applications of this type include engine covers, hood covers, dash silencers, parts placed inside tires, interior and exterior materials such as instrument panels, pillar garnishes, consoles, door trims, and vehicle bodies, vehicle interiors, and other vehicle interiors. It is possible to imagine a member that partitions the structure (such as a trunk room). The structure of the soundproofing member can be appropriately set depending on the main use for soundproofing, the auxiliary use (reinforcement, raising, etc.), the required sound absorption and sound insulation properties, and the like.

Further, in this embodiment, the configurations (shape, dimensions, arrangement position, number of formations, etc.) of the first soundproofing part and the second soundproofing part are illustrated, but this is not intended to limit the configuration of each of these parts. For example, the first soundproofing section may have various three-dimensional shapes such as a plate shape or a columnar shape. Moreover, the shape of the second soundproofing part can also be changed as appropriate according to the first soundproofing part, and can be integrated into substantially all or part of the first soundproofing part. For example, a part of the first soundproofing part may be intentionally provided with a part where the second soundproofing part is not arranged, and the part can be bent and deformed at that part. Note that the soundproofing properties of each soundproofing part are generally based on 1000Hz, but do not necessarily need to be based on 1000Hz. That is, although the first soundproofing section is intended to be soundproofing against high-frequency sounds, the sound does not necessarily have to be 1000Hz or higher, and may be slightly lower than 1000Hz within the range of error. Further, the second soundproofing section is intended to be soundproofing for sounds of a different frequency from that of the first soundproofing section, and the sound does not necessarily have to be less than 1000Hz, and may be higher than 1000Hz.

In addition, the shape of the convex part forming the hollow structure of the second soundproofing part may be various columnar shapes such as a truncated quadrangular pyramid, rectangular parallelepiped, or cube, cylindrical shapes such as a cylindrical shape, a truncated cone shape, or a hollow cylinder shape, or a hemispherical shape. Various three-dimensional shapes such as can be adopted. The shapes and dimensions of the plurality of convex parts can be set independently, and the number of communicating parts and the opening area of the passage parts can also be set independently. Further, in the soundproofing member, at least one of each side wall portion can be sloped so as to form a hat cross section. For example, in this embodiment, only one side wall portion can be sloped. Note that the side wall portion may be linearly inclined, may be bent and inclined like a step shape, or may be curved and inclined so as to form a curved surface. Further, the ceiling wall portion may have a curved surface such as a semicircular shape, or may be formed by appropriately combining a curved surface and an inclined surface. In addition, a plurality of communication parts or a single communication part can be formed on each wall of the convex part. For example, the communication part can be formed on the ceiling wall, the front wall, the rear wall, the right side wall, and the left side wall as appropriate. It can be provided at any location. Note that the configurations of each embodiment can be used in combination as appropriate. In Embodiment 3, by providing a standing wall-like rib on the inner surface of the lid, the back space can be divided into convex portions, and the rigidity of the lid can be further increased. Further, the lid of Embodiment 3 may be provided with a portion that follows the convex portion, and may have a shape in which the convex portion and the bottom wall portion shown in FIG. 3 are reversed front to back, for example.

Further, in this embodiment, although the configuration of the lid portion, the integral hinge portion, and the latch structure is illustrated, this is not intended to limit the configuration of each of these parts and the latch structure. For example, the lid portion can be provided at an appropriate position on the bottom wall portion, and a pair of upper and lower lid portions or left and right lid portions can be provided in a state that they can be opened double-sidedly. Further, the latch structure can be provided at an appropriate position of the second soundproofing part, and a plurality or one latch structure can be provided at an appropriate position on the upper edge or the left and right edges. Note that the latch structure may be formed with a hook structure or a clip structure, or may be formed with a fastener such as a bolt material, and may be omitted if necessary. Note that if the latch structure is omitted, the lid part can be fixed to the bottom wall part by a method such as adhesion.

Further, in this embodiment, although a method for manufacturing a soundproof member is illustrated, this is not intended to limit the manufacturing method. For example, the protrusion can be formed on at least one of the first type and the second type, and the configuration of the protrusion can also be appropriately set depending on the configuration of the communication part. The soundproofing member of this embodiment can be used not only for vehicle components such as interior and exterior parts of a vehicle, but also for various structures such as houses and soundproof walls.

2 Vehicle 3 Vehicle body 4 Compartment 5 Engine compartment 6 Dash panel 7 Hood panel 8 Front side member EN Engine 10 Soundproofing member 11 First soundproofing section 11X Molding material for the first soundproofing section 12 Second soundproofing section 12a Second soundproofing section Inner surface 12b Outer surface 14 of second soundproofing portion Bottom wall portion 15 Convex portion (hollow structure of the present invention)
20 Ceiling wall section 21 Lower wall section 22 Upper wall section 23 Right side wall section 24 Left side wall section 30 Communication section 32 Passage section OP1 First opening section OP2 Second opening section (opening section of the present invention)
40 Integral hinge portion 41 Lid portion 42 Flange portion 44 Latch structure 45 Locking wall portion 46 Locking projection 47 Locking hole portion 50 Helmholtz resonator 51 Internal space of Helmholtz resonator 52 Communication portion OP of Helmholtz resonator Opening 60 Pulp Molding die 61 for molding Molding surface 62 Net material 63 Liquid suction part 611 Convex part 612 Flat part 613 Concave part 614 Flat surface 68 Stock solution 70 Molding device 71 First mold 72 Second mold 73 Cavity 74 Projection part 10A Embodiment Soundproofing member 40A of Embodiment 2 Integral hinge part 41A of Embodiment 2 Lid part 10B of Embodiment 2 Soundproofing member 40B of Embodiment 3 Integral hinge part 41B of Embodiment 3 Lid part 80 of Embodiment 3 Back space part 411 Bottom plate part 412 Circumferential plate part

Claims (4)

A soundproofing member comprising a first soundproofing part suitable for absorbing high-frequency sound and a second soundproofing part suitable for absorbing sound of a different frequency from the first soundproofing part,
The first soundproofing part made of a foamed resin having an open cell structure and the second soundproofing part having a hollow structure and having higher rigidity than the first soundproofing part are integrally molded,
The first soundproofing part is integrated around the second soundproofing part with an opening of the hollow structure exposed,
The second soundproofing part has the opening at one end, and the other end opposite to the one end is closed by a lid part,
The lid part is integrally formed with the second soundproof part via an integral hinge part provided on one edge that forms a part of the outer edge of the second soundproof part, and the lid part is integrally formed with the second soundproof part, and The hollow structure is brought into a closed state by being folded back from the state of protruding toward the side using the integral hinge portion as a base point, and the second soundproofing portion is folded back from a state of being overhanging toward the other side, and the second soundproofing portion is folded back to close the hollow structure. and is locked to the second soundproofing part,
In the latch structure, the soundproofing member includes a locking protrusion integrally formed in the second soundproofing portion and locked in a locking hole portion integrally formed in the lid portion. The soundproofing member according to claim 1, wherein the second soundproofing part is formed of a member in which a plurality of cellulose fibers are integrated in a laminated state. The soundproofing member according to claim 1 or 2, wherein the second soundproofing part is embedded and integrated with the first soundproofing part forming the outer shape of the soundproofing member. In the method for manufacturing a soundproofing member according to any one of claims 1 to 3,
The molding device for molding the first soundproofing part is formed between a first mold, a second mold that can be closed to the first mold, and the first mold and the second mold in a closed state. a cavity, and a protrusion that can be inserted into the opening is provided at a portion facing the cavity of at least one of the first mold and the second mold,
After inserting the protrusion into the opening and installing the second soundproofing part in the one mold, the first mold and the second mold are closed together, and then the first soundproofing part is inserted into the cavity. While foaming and hardening the molding material,
Prior to molding the first soundproofing part, the hollow structure is closed by bending the lid part back about the integral hinge part provided on one edge that forms a part of the outer edge of the second soundproofing part. A method for manufacturing a soundproofing member, in which the soundproofing member is engaged with the second soundproofing part via the latch structure provided on an outer edge portion of the second soundproofing part opposite to the one edge .

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