JP2009149117A - Sound absorbing structure for automobile ceiling, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a thin thickness, and to enhance sound absorbing performance at a wide sound area. <P>SOLUTION: A ceiling material 10 is constituted by forming a membrane sound absorbing part 12 in a surface of a panel body 11 comprising a porous material 11A. The membrane sound absorbing part 12 comprises a recess 15 formed on the panel body 11 and a sound absorbing body 16 provided in the recess 15, and a plurality of membrane sound absorbing parts are formed on the surface of the panel body 11. The sound absorbing body 16 comprises a porous material 18 and a skin layer 19 formed on an outer peripheral surface side of the porous material 18. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure for a car ceiling and a method for manufacturing the same, and more particularly to a sound absorbing structure for a car ceiling and a method for manufacturing the same, which can improve sound absorbing performance while reducing the thickness.

Conventionally, comfort as an acoustic space has been required in the interior of an automobile, and in order to realize such a demand, for example, as disclosed in Patent Documents 1 and 2, a structure for absorbing sound by a ceiling material is known. It has been.
The ceiling material of Patent Document 1 has a structure in which a dense layer is laminated on the surface of an intermediate layer whose main constituent substrate is polyester fiber.
The ceiling material of Patent Document 2 has a structure in which a skin obtained by laminating a low-breath slab urethane on a surface layer sheet is laminated on the surface of a base material.

Japanese Patent No. 3480179 Japanese Patent No. 3656232

In Patent Document 1, a sound absorbing action is obtained by an intermediate layer using polyester fiber, and in Patent Document 2, a sound absorbing action is obtained by slab urethane of the skin. In other words, in Patent Documents 1 and 2, since sound absorption is performed only with the porous material, when the ceiling material is mounted in a vehicle with a thickness (specifically, about 10 mm to 30 mm), the frequency is This causes a disadvantage that the sound absorbing performance in the middle and low range of 400 Hz or less cannot be obtained sufficiently.
Here, if the thickness is formed to be large, the sound absorption performance in the middle and low range can be slightly improved, but it cannot be said that the sound absorption performance is sufficient, and is not suitable for mounting in a vehicle having a relatively narrow space. There is an inconvenience.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and an object of the present invention is to provide a motor vehicle that can be thinned and can improve sound absorption performance in a wide sound range including a mid-low range. An object is to provide a sound absorbing structure for a ceiling and a method for manufacturing the same.
Another object of the present invention is to provide an automobile ceiling sound absorbing structure that can be easily manufactured and a method for manufacturing the same.

  In order to achieve the above object, the sound absorbing structure for an automobile ceiling according to the present invention employs a structure in which a film sound absorbing portion is provided in the surface of a panel body made of a porous material.

In the present invention, a plurality of the film sound absorbing parts are provided in the surface of the panel main body including a concave portion formed in the panel main body, and a sound absorbing body provided in the concave portion,
It is preferable that the sound absorber has a porous material and a non-breathable surface layer that forms a closed region while being formed on the outer peripheral surface of the porous material.

Further, the film sound absorbing portion is provided in the surface of the panel main body, comprising a concave portion formed in the panel main body, and a sound absorbing body provided in the concave portion,
The sound absorber may include a non-breathable membrane that forms a closed region inside.

  Furthermore, it is preferable to provide a porous material in the closed region.

  The membrane sound absorbing portion is formed in a part of the outer peripheral surface region of the porous material forming the panel main body, and includes a non-breathable surface layer forming a closed region, and a plurality of sound absorbing portions are provided in the surface of the panel main body. A configuration of being provided may be adopted.

  Further, the membrane sound absorbing portion is formed of a dent portion formed in the panel body, a non-breathable surface layer formed at the bottom of the dent portion, and a membrane shape stretched at a position closing the opening side of the dent portion. The structure which is provided with a body and is provided in the surface of a panel main body may be taken.

In addition, the method for manufacturing a sound absorbing structure for an automobile ceiling according to the present invention is formed before or after forming a plurality of recesses in the surface of the panel body.
Partially melting the porous material, forming a surface layer on the outer peripheral surface side of the porous material, producing a sound absorber that forms a closed region by the surface layer,
Then, the method of arrange | positioning a sound absorption body in each dent part, respectively is taken.

  Furthermore, the present invention provides a non-breathable surface layer by melting a part of the outer peripheral surface region of the porous material, and after producing an intermediate material in which a region closed by the surface layer is formed, The method is to form the panel body by shaping.

  According to the present invention, a membrane vibration type sound absorbing action can be achieved by the membrane sound absorbing portion, so that the sound absorbing performance in the middle and low frequency ranges of 400 Hz or less can be improved, and the overall thickness is increased. It becomes possible to suppress. In addition, the sound absorption performance in the high range can be improved by the porous material forming the panel body, and the sound absorption in a wide sound range can be realized.

  Further, by arranging the sound absorber in the recess of the panel body, it is possible to easily achieve a sound absorbing action in the middle and low range due to the vibration of the surface layer and the sound absorber in the sound absorber, and the sound absorber's porous material Therefore, sound absorption performance can be further improved. Moreover, since the sound absorber is disposed in the recess, it is possible to suppress an increase in the overall thickness. And even if it is a panel main body already mounted, a film | membrane sound-absorbing part can be easily formed by forming a dent part and arrange | positioning a sound-absorbing body, and can be easily applied also to the existing motor vehicle.

  Furthermore, by melting a part of the outer peripheral surface area of the porous material forming the panel body to form the surface layer, the sound absorption effect by the surface layer can be obtained in the same manner as described above, and the panel body and the surface layer are formed integrally. can do. Thereby, not only can the manufacturing process be simplified, but also the panel body can be easily attached to the automobile.

  Further, by forming the surface layer by melting a porous material, it is possible to obtain a sound absorbing effect by membrane vibration while achieving a reduction in thickness.

  Furthermore, even if a film sound absorbing portion is provided by stretching a film-like body in the recess, it is possible to obtain a sound absorbing action similar to that of the surface layer described above.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1A is a schematic cross-sectional view schematically showing a ceiling material to which the sound absorbing structure according to the first embodiment is applied. In this figure, the ceiling material 10 is disposed in the room of the automobile C and is provided in a curved shape along the lower surface of the roof C1. The ceiling material 10 includes a panel main body 11 and a plurality of film sound absorbing portions 12 provided on the surface of the panel main body 11 at a predetermined interval.

  The panel body 11 is formed by heating and compressing the porous material 11A using a mold apparatus described later. The thickness of the panel body 11 is set to 10 to 50 mm. The porous material 11A forming the panel main body 11 may be made of the same material as or different from the sound absorbing porous material described later.

The film sound absorbing portion 12 includes a recessed portion 15 formed on a surface (upper surface in FIG. 1A) of the panel body 11 facing the roof C1, and a sound absorbing body 16 provided in the recessed portion 15. Become.
The recess 15 is provided in substantially the same planar shape as the sound absorber 16, and the depth thereof is set so that the thickness of the panel body 11 that forms the bottom of the recess 15 is 0.05 mm to 10 mm. .

  The sound absorber 16 includes a porous material 18 and a surface layer 19 formed on the outer peripheral surface side of the porous material 18, and is formed in a sheet shape along a surface extending in a direction orthogonal to the paper surface of FIG. ing. Examples of the planar shape of the sound absorber 10 include a square, a rectangle, a circle, an ellipse, and a polygon. Further, in the present embodiment, the sound absorber 10 has a cross-sectional shape in which the upper and lower surfaces in the drawing are arc-shaped, and the thickness gradually decreases toward the outer edge.

The porous material 18 is made of a material having a capillary such as fibers such as a nonwoven fabric or a material having open cells such as a foam, and when sound is incident, the sound wave is in contact with the peripheral wall in the pores. A part of sound energy can be consumed as heat energy by friction, viscous resistance and vibration of material fibrils. The porous material 18 is configured to be meltable as described later using a thermoplastic polymer, and if necessary, a plasticizer such as an organic low molecule or a filler made of an inorganic material for improving internal loss is inserted. It may be a composite material.
Examples of the thermoplastic polymer include TPO (olefin elastomer), CPE (chlorinated PE), PVC (vinyl chloride), PET, polyester, synthetic rubber (isoprene rubber, nitrile rubber, fluorine rubber, etc.), silicon rubber, PE Can be illustrated.
Examples of the plasticizer include phthalate ester plasticizers, crosslinking accelerators such as DBS, aging / antioxidants, and fillers include calcium carbonate, calcium silicate, mica, carbon black, PZT, and silica. .

  The surface layer 19 is formed by melting the outer peripheral surface side of the porous material 18 as will be described later, and is provided in the form of an air-impermeable thin film that is integrated with the porous material 18. The surface layer 19 covers all outer peripheral surfaces including both front and back surfaces and end surfaces of the porous material 18, and forms a closed region in which the porous material 18 is located. The thickness of the surface layer 19 is set to 0.3 to 3 mm, and is provided so that sound energy can be consumed by internal loss when sound enters.

  Next, a method for manufacturing the ceiling material 10 will be described.

  When producing the panel main body 11 to manufacture the ceiling material 10, a mold apparatus 21 shown in FIG. 2A is used. The mold apparatus 21 includes an upper mold 23 and a lower mold 24 having a molding space 22 corresponding to the outer shape of the panel body 11. With the mold device 21 opened, a sheet-like porous material 11A having a thickness of about 50 mm is disposed between the upper mold 23 and the lower mold 24. Thereafter, as shown in FIG. 2 (B), the porous material 11A is pressed while being heated to be shaped into a shape corresponding to the molding space 22, and after a predetermined keeping time has elapsed, from the mold device 21 to the panel. The main body 11 is taken out.

With respect to the panel main body 11 thus manufactured, the panel main body 11 is scraped off at a position indicated by a dotted line in FIG. 3A, and a plurality of in-planes of the panel main body 11 are formed as shown in FIG. A recess 15 is formed. Before and after the formation of the recess 15, the sound absorber 16 is manufactured using a mold apparatus 27 as shown in FIG. The mold device 27 includes an upper mold 29 and a lower mold 30 having a molding space 28 corresponding to the outer shape of the sound absorber 16.
When the sound absorber 18 is manufactured by the mold device 27, first, the sheet material porous material 18 having a thickness of about 50 mm is disposed between the upper mold 29 and the lower mold 30 with the mold apparatus 27 opened. . After that, as shown in FIG. 4B, a step of forming the surface layer 19 is performed in which the mold is closed, and the porous material 18 is heated and compressed in the thickness direction through the upper mold 29 and the lower mold 30. . As a result, the outer peripheral surface side of the porous material 18 is partially melted to form a thin-film surface layer 19, and the porous material 18 is covered with the surface layer 19. After elapse of a predetermined keep time, the mold device 27 is opened to complete the production of the sound absorber 18 having a thickness of 10 to 30 mm. At this time, when a part of the surface layer 19 protrudes from the outer edge of the sound absorber 18, it is preferable to perform a process of cutting a part of the surface layer 19.

  After producing the sound absorber 18, as shown in FIG. 3B, the sound absorber 18 is disposed inside each recess 15 of the panel body 11, and the end of the sound absorber 18 and the recess 15 By attaching the sound absorber 18 to the panel body 11 by bonding or the like, the ceiling material 10 is completed.

  As shown in FIG. 5 (A), the step of forming the recessed portion 15 was performed by forming the recessed portion 11B at a position corresponding to the recessed portion 15 of the porous material 11A before being put into the mold apparatus 21. You may carry out by shaping a thing like the above-mentioned. Further, as shown in FIG. 5B, after forming a through hole 15A at a position corresponding to the recessed portion 15 of the panel body 11, a sheet material 32 is pasted on the lower surface side of the panel body 11 in the figure. Also good.

  Therefore, according to the first embodiment, it is possible to perform sound absorption by the porous material 18 of the panel body 11 and the sound absorber 16 and membrane vibration type sound absorption by the surface layer 19 of the sound absorber 16. As a result, the ceiling material 10 as a whole can be made thinner while expanding the sound range in which a good sound absorbing effect can be obtained.

  Next, embodiments other than the first embodiment of the present invention will be described. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals as necessary, and the description is omitted or simplified.

[Second Embodiment]
6A to 6C show a second embodiment of the present invention. In the ceiling material 10 of the second embodiment, the membrane sound absorbing portion 12 is formed by partially melting the outer peripheral surface region of the porous material 11A forming the panel body 11 at a plurality of locations.

  When the ceiling material 10 according to the present embodiment is manufactured, first, a flat-sized porous material 11A corresponding to the ceiling material 10 is prepared by mixing a thermosetting resin powder such as an epoxy resin or a phenol resin. Next, as shown in FIG. 6B, the porous material 11A is melted by the hot press device 35 in the same manner as the mold device 27 of the first embodiment, and the upper and lower surfaces of the porous material 11A are impermeable to air. The step of forming the surface layer 19 is performed. By carrying out this process at a plurality of locations at a predetermined interval on the porous material 11A, an intermediate material 36 having a plurality of film sound absorbing portions 12 in the plane is formed, as shown in FIG. 6C. The Thereafter, as shown in the figure, the intermediate material 36 is put into the mold apparatus 21, and the region where the surface layer 19 is not formed is heated and compressed so as to have the same thickness as the film sound absorbing portion 12. 36 is shaped. At this time, the thermosetting resin powder is cured and compressed so as to spot the porous material 11A. As a result, the panel body 11 is formed as shown in FIG. 6A, and the ceiling material 10 having elasticity and sound absorption characteristics with respect to the pressing of the panel body 11 is completed.

  According to such 2nd Embodiment, the film | membrane sound absorption part 12 of the panel main body 11 can be formed integrally, and it becomes possible to improve the handleability in the attachment operation | work of the ceiling material 10, etc.

[Third Embodiment]
7A and 7B show a third embodiment of the present invention. The film sound absorbing portion 12 of the third embodiment includes a recess 15 formed in the panel body 11, a non-breathable surface layer 38 formed at the bottom of the recess 15, and an upper opening side of the recess 15. And a film-like body 39 stretched so as to form a closed and closed space. The surface layer 38 is formed simultaneously with the recessed portion 15 by pressing a heated convex mold on the upper surface of the panel body 11. The film-like body 39 can perform a membrane vibration type sound absorption, and can obtain a sound absorption action similar to that of the first embodiment.

  Examples of the present invention will be described below together with comparative examples.

[Example 1]
In Example 1, the ceiling material 10 having the same structure as that of the first embodiment was produced except that the front and back surfaces of the panel body 11 were substantially flat. The planar shape of the ceiling material 10 as a whole is a square of 1000 mm × 1000 mm, the planar shape of the film sound absorbing portion 12 is a square of 150 mm × 150 mm, and the film sound absorbing portions 12 are provided in four rows vertically and horizontally in plan view. And the pitch interval in the horizontal direction was 250 mm. Further, the thickness of the panel body 11 is 10 mm, the thickness of the sound absorber 16 is 10 mm, the thickness of the panel body 11 that forms the bottom of the recess 15, the maximum thickness 15 mm of the ceiling material 10 in the region where the sound absorber 16 is provided, and the surface layer 19. The thickness was 1 mm. The porous material 11A forming the panel body 11 and the porous material 18 of the sound absorber 16 were made of PVC nonwoven fabric.

[Example 2]
In Example 2, the ceiling material 10 having the same structure as that of the second embodiment was produced except that the front and back surfaces of the panel body 11 were substantially flat. The panel body 11 and the film sound absorbing portion 12 were each set to have a thickness of 10 mm.

[Comparative Example 1]
In Comparative Example 1, a square glass wool having a thickness of 10 mm and a planar shape of 1000 mm × 1000 mm was used.

In evaluating the sound absorbers of Examples 1 and 2 and Comparative Example 1, random incident sound absorption rate was used as an evaluation index. The random incident sound absorption coefficient is referred to as a reverberation room sound absorption coefficient, and is calculated from the decay time of the reverberation room when a sound is emitted in the reverberation room and stopped suddenly by a method according to JIS A 1409.
In each Example and Comparative Example 1, a PLD (Power Law Decay) correction method (J. Acous. Soc. Jpn.) Is used to estimate and calculate reverberation time under complete diffusion by fitting a theoretical equation to a curved reverberation decay waveform. (E) 19, 5 (1998) 315-326), and the Deep-well method (J. Acous. Soc. Jpn. (E) for suppressing the area effect by installing an acrylic plate enclosure (Deep well) around the material. ) 19, 5 (1998) 327-338).
In each Example and Comparative Example 1, as shown in FIG. 8, the volume (V) is 64 m ³ , the surface area (S) is 100 m ² , and V / S = 0.64. The ceiling material 10 of each Example and each Comparative Example having a size of 1 m in length and 1 m in width is installed, and a diffusion frame plate 42 having a height of 800 mm made of an acrylic plate having a thickness of 20 mm is installed around the ceiling material 10. did. The sound source 43 is arranged at a position away from the ceiling material 10. In this way, sound (air vibration due to sound) is incident on the surface 10a of the ceiling material 10 from a random direction.
The graph of FIG. 9 shows the result of the sound absorption coefficient of each example and each comparative example.

The greater the sound absorption rate, the better the sound absorption performance. However, in actual physical sensation, if the sound absorption rate is 0.40 or more, the effect can be realized and it can be said that the sound absorption material is good.
Here, in the graph of FIG. 9, when looking at the center frequency at which the sound absorption rate of Examples 1 and 2 and Comparative Example 1 is 0.40 or more, Comparative Example 1 has only a high frequency range of 2500 Hz, In Examples 1 and 2, although it is slightly lower than 0.40 at 400 Hz of Example 2, it becomes 315 Hz or higher high frequency range and middle low frequency range, and compared with Comparative Example 1, Examples 1 and 2 have better sound absorption performance. It can be understood that the sound range that becomes good becomes wider.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this.
That is, the present invention has been particularly shown and described with respect to specific embodiments, but the embodiments and examples described above are not deviated from the technical idea and scope of the present invention. On the other hand, those skilled in the art can add various modifications in shape and other detailed configurations.

  For example, the cross-sectional shape of the sound absorber 16 of the first embodiment can be changed in various designs, and may be the shapes shown in FIGS. In FIG. 10A, the upper and lower surfaces are parallel to each other, and the end surfaces are formed to be orthogonal to the upper and lower surfaces. 10B, the upper and lower sides of the end face in FIG. 8A are chamfered so that the middle part in the thickness direction of the end is pointed. In FIG. 10C, the upper side of the end face in FIG. Is chamfered and the lower part of the end is formed into a sharp shape. In FIG. 10D, the upper surface is arcuate and the lower surface is flat.

Moreover, the design of the sound absorber 16 of the first embodiment can be changed to the structure shown in FIGS. 11 (A) and 11 (B). The sound absorbing body 16 in FIG. 11A is provided with a non-breathable film-like body 50 so as to have the same structure as the surface layer 19 of the embodiment, and a closed region is formed inside the film-like body 50. ing. The sound absorbing body 16 is formed by forming the two film-like bodies 50 so that one surface bulges, and then joining the outer peripheral sides to each other so that the bulging surfaces are outside. Forming.
The sound absorber 16 in FIG. 11B is obtained by separately providing a sheet-like porous material 51 in the closed region of the sound absorber 16 in FIG.

  Furthermore, the sound absorbing portion 12 of the third embodiment may be configured such that a porous material 53 is separately provided inside the recessed portion 15 as shown in FIG.

  The formation of the porous materials 18 and 11A may be performed by a step of dissolving the outer peripheral surfaces of the porous materials 18 and 11A with a solvent. At the time of compression by the upper die 22 and the lower die 23 or the press device 35 after this step, they need not be heated. Moreover, it is preferable to make the melt | dissolution method with a solvent into the method of spraying a solvent on the porous materials 18 and 11A with a spray. However, in the first embodiment, the porous material 11 may be directly immersed in a tank containing a solvent.

(A) is a schematic cross-sectional view schematically showing a ceiling material to which the sound absorbing structure according to the first embodiment is applied, and (B) is an enlarged view of a portion A in (A). (A) is a cross-sectional view of a preparation stage for manufacturing a panel body, and (B) is a cross-sectional view during manufacturing of the panel body. (A) is a cross-sectional view for explaining the step of forming the recess, and (B) is a cross-sectional view for explaining the step of attaching the sound absorbing part. (A) is a cross-sectional view of a preparation stage for producing a sound absorber, and (B) is a cross-sectional view during production of the sound absorber. (A) is a cross-sectional view of the porous material which forms the panel main body which concerns on a modification, (B) is a cross-sectional view of the panel main body which concerns on another modification. (A) is a cross-sectional view similar to FIG. 1 (A) of the ceiling material according to the second embodiment, (B) is a cross-sectional view of a preparation stage for producing the intermediate material of the embodiment, (C) FIG. 3 is a cross-sectional view of a preparation stage for producing the panel body of the embodiment. (A) And (B) is a cross-sectional view similar to FIG. 1 (A) and (B) of the ceiling material which concerns on 3rd Embodiment. Explanatory drawing of the reverberation room which measures a sound absorption coefficient. The graph showing the sound absorption rate of Examples 1, 2 and Comparative Example 1. (A)-(D) are the cross-sectional views of the sound-absorbing body which concerns on another modification. (A) And (B) is a cross-sectional view of the sound absorber according to the modification of the first embodiment. The cross-sectional view of the sound absorber according to a modification of the third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Ceiling material, 11 ... Panel main body, 12 ... Membrane sound absorption part, 15 ... Recessed part, 16 ... Sound absorption body, 18 ... Porous material, 19 ... Surface layer, 36 ... Intermediate material, 39 ... Membrane, C ... Automobile

Claims (8)

  A sound absorbing structure for an automobile ceiling, characterized in that a film sound absorbing portion is provided in a plane of a panel body made of a porous material. The film sound absorbing portion is provided in a plane of the panel main body including a concave portion formed in the panel main body and a sound absorbing body provided in the concave portion,
2. The automobile ceiling according to claim 1, wherein the sound absorber includes a porous material and a non-breathable surface layer that is formed on an outer peripheral surface of the porous material and forms a closed region. Sound absorbing structure. The film sound absorbing portion is provided in a plane of the panel main body including a concave portion formed in the panel main body and a sound absorbing body provided in the concave portion,
The sound absorbing structure for an automobile ceiling according to claim 1, wherein the sound absorbing body includes a non-breathable film-like body that forms a closed region inside.   The sound absorbing structure for automobile ceiling according to claim 3, wherein a porous material is provided in the closed region.   The membrane sound absorbing portion is formed in a part of the outer peripheral surface region of the porous material forming the panel body, and includes a non-breathable surface layer forming a closed region, and a plurality of the sound absorbing portions are provided in the surface of the panel body. The sound absorbing structure for an automobile ceiling according to claim 1, wherein   The film sound absorbing portion includes a recess formed in the panel body, a non-breathable surface layer formed at the bottom of the recess, and a film-like body stretched at a position closing the opening side of the recess. The sound absorbing structure for an automobile ceiling according to claim 1, wherein a plurality of the sound absorbing structures are provided in the surface of the panel body. Before or after forming a plurality of recesses in the surface of the panel body,
Partially melting the porous material, forming a surface layer on the outer peripheral surface side of the porous material, producing a sound absorber that forms a closed region by the surface layer,
Thereafter, a sound absorbing body is disposed in each recess, and the method for manufacturing a sound absorbing structure for an automobile ceiling is provided.   A part of the outer peripheral surface of the porous material is melted to form a non-breathable surface layer, and after producing an intermediate material in which a closed region is formed by the surface layer, the intermediate material is shaped and the panel body The manufacturing method of the sound-absorbing structure for vehicle ceilings characterized by forming.

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