JP4752449B2 - Sound absorbing material for vehicles - Google Patents

Description

  The present invention relates to a vehicle sound absorbing material for reducing vehicle noise.

Providing a non-breathable thin film (film) on the back of a breathable ceiling base material made of felt or non-woven fabric by heat-pressure molding or point bonding, and improving sound absorption performance by film vibration of the thin film It is considered (for example, refer to Patent Document 1).
JP-A-6-43880 JP 2004-130731 A

  However, in the conventional technology as described above, the sound absorption performance as a whole of the molded ceiling material is considered, but the sound absorption performance for each part (unit section) in the assembled state to the vehicle is not considered, and this There is room for improvement.

  In view of the above fact, an object of the present invention is to obtain a sound absorbing material for a vehicle that can set sound absorbing characteristics of each part in accordance with a relationship with a noise reduction target position.

In order to achieve the above object, a vehicle sound absorbing material according to the first aspect of the present invention is a vehicle in which a surface acoustic wave reflector is placed in contact with a surface of the sound absorbing base material opposite to the incident side of the sound to be absorbed. A sound absorbing material for use, wherein the planar sound wave reflector is partially fixed to the sound absorbing base material at a predetermined interval, and the fixing portion between the planar sound wave reflector and the sound absorbing base material is predetermined intervals, the respectively set for each unit section of sound-absorbing base material, that have a portion that the predetermined interval is different in adjacent unit blocks.

  In the vehicle sound-absorbing material according to claim 1, since the fixed interval of the planar sound wave reflector with respect to the sound-absorbing substrate is set for each unit section of the sound-absorbing substrate (vehicle sound-absorbing material), It is possible to set the natural frequency of the surface acoustic wave reflector for each unit section (different as necessary). Thereby, the sound absorption (auxiliary) effect using the vibration (characteristics) of the planar sound wave reflector disposed in contact with the sound absorbing base material is obtained for each unit section of the sound absorbing base material (that is, in the vehicle sound absorbing material). (Depending on the position or direction relative to one or more noise reduction target positions).

  Thus, in the vehicle sound absorbing material according to the first aspect, the sound absorbing characteristics of each part can be set according to the relationship with the noise reduction target position. The unit section may be an actual section or a virtual section, and each section may have a different shape or size.

  The sound absorbing material for a vehicle according to a second aspect of the present invention is the sound absorbing material for a vehicle according to the first aspect, wherein the predetermined interval between the fixed portions of the surface acoustic wave reflector and the sound absorbing base material is the fixed portion. In the meantime, the planar sound wave reflector is set as an oscillating interval that comes in contact with and separates from the sound absorbing substrate.

  In the vehicle sound-absorbing material according to claim 2, for example, when a specific sound is incident on the sound-absorbing base material, the surface acoustic wave reflector vibrates while being in contact with and away from the sound-absorbing member between the fixed portions to the sound-absorbing base material. . Since the sound absorption target frequency can be changed in accordance with the change (including presence or absence) of the reflection position of the incident sound due to the separation (amplitude) of the planar sound wave reflector from the sound absorption base material, the interval between the fixed parts That is, the desired sound absorbing performance can be easily obtained for each unit section by setting the amplitude of the planar acoustic wave reflector between the fixed parts.

  A sound absorbing material for a vehicle according to a third aspect of the present invention is the sound absorbing material for a vehicle according to the second aspect, wherein the predetermined interval for each unit section between the fixed portions of the surface acoustic wave reflector and the sound absorbing base material. Is set as an interval in which the planar sound wave reflector is primarily vibrated with contact with and separated from the sound absorbing base material between the fixed portions by sound waves having a frequency determined for each unit section.

  In the vehicle sound-absorbing material according to claim 3, for each unit section of the sound-absorbing base material, the surface acoustic wave reflector is in contact with or separated from the sound-absorbing base material between the fixed portions, and the primary vibration (with a single amplitude between the fixed portions). The frequency of the incident sound wave that causes anti-node vibration) is set, and the amplitude (reflection position of the incident sound) of the planar sound wave reflector of each unit section is set based on the set frequency for each unit section Thus, it is possible to easily realize the sound absorption performance according to the applied vehicle.

  The vehicle sound absorbing material according to a fourth aspect of the present invention is the vehicle sound absorbing material according to the third aspect, wherein the predetermined interval between the unit sections between the fixed portions of the planar sound wave reflector and the sound absorbing base material. Is set as an interval at which the peak of the sound absorption coefficient in each unit section occurs at a frequency determined for each unit section.

  In the vehicle sound-absorbing material according to claim 4, the sound absorption coefficient peaks at a predetermined frequency in each unit section. Thereby, the sound absorption characteristics of each part are optimized according to the relationship with the noise reduction target position, and a good noise reduction effect is obtained at the noise reduction target position.

  The sound absorbing material for a vehicle according to a fifth aspect of the invention is the sound absorbing material for a vehicle according to any one of the first to fourth aspects, wherein the sound absorbing base material has air permeability and is absorbed from the vehicle interior side. It arrange | positions so that target sound may enter, and the said planar sound wave reflector has air permeability, and is contacting the opposite side to the said vehicle interior side in the said sound-absorbing base material.

  In the vehicle sound-absorbing material according to claim 5, the sound-absorbing base material itself exhibits a sound-absorbing performance utilizing its air permeability, and the planar sound wave reflector functions as a sound-absorbing base material. By setting the fixed interval of the surface acoustic wave reflector with respect to the sound absorbing substrate for each unit section, a sound absorption (auxiliary) effect using the vibration (characteristic) of the surface acoustic wave reflector can be obtained without providing an additional member. be able to.

  As described above, the vehicle sound absorbing material according to the present invention has an excellent effect that the sound absorbing characteristics of each part can be set according to the relationship with the noise reduction target position.

  A roof lining 10 as a vehicle sound absorbing material according to an embodiment of the present invention will be described with reference to FIGS. In the figure, the arrow FR indicates the front direction of the vehicle body, and the arrow UP indicates the upward direction of the vehicle body.

  FIG. 3 is a side sectional view of the roof portion 14 of the automobile 12 to which the roof lining 10 is applied. As shown in this figure, in the roof portion 14, a roof panel 16 that is a vehicle body outer plate includes a pair of left and right roof side rails (not shown) that are skeleton members along the vehicle body longitudinal direction, and the pair of roof side rails. Is supported by a roof cross member 18 that is bridged.

  The roof panel 16 is covered from below, that is, from the inside of the passenger compartment 25 by the roof lining 10 over substantially the entire surface. The roof lining 10 is not in contact with the roof panel 16 and the roof cross member 18, and a back air layer 20 is formed between them, that is, above the roof lining 10. In addition, the code | symbol 22 in FIG. 3 has shown the front windshield glass.

  As shown in FIG. 1, the roof lining 10 includes a lining base material 24 as a sound absorbing base material, a skin material 26 fixed to the surface 24A of the lining base material 24 on the vehicle interior 25 side by adhesion, and the lining base material. 24 is configured to include a ventilation stopper film 28 as a planar sound wave reflector provided so as to be in contact with the entire surface 24B of the rear air layer 20 side of 24.

  The lining substrate 24 is made of a breathable material such as felt or urethane foam, and absorbs vibration (sound) of air passing therethrough. The skin material 26 is exposed to the passenger compartment 25 and constitutes the design surface of the roof lining 10. The air blocking film 28 blocks the ventilation of the air-permeable lining base material 24 and suppresses the dirt on the skin material 26. Further, the air blocking film 28 is configured to exhibit an incident sound reflecting action in the roof lining 10.

  Here, the roof lining 10 partially fixes the air blocking film 28 to the lining substrate 24 by point bonding. Reference numeral 30 shown in each drawing is a fixing portion of the air-blocking film 28 to the lining substrate 24 by point adhesion. Thereby, in the roof lining 10, when the noise (sound wave) shown in FIG. 2 is incident, the portion 28A between the fixing portions 30 in the air-blocking film 28 is fixed by the sound pressure of the sound wave that has passed through the lining substrate 24. A primary mode vibration is generated with an operation of separating the portion 30 toward the back air layer 20 with respect to the surface 24A of the lining substrate 24 with the portion 30 as a fulcrum (vibration node).

  Therefore, the air-blocking film 28 vibrates toward the back air layer 20 (using the back air layer 20), and reflects the reflection position of the sound wave by the portion 28A separated from the surface 24B of the lining base material 24 to the adjacent fixed portion. It is configured to change according to 30 intervals. In other words, the roof lining 10 sets the separation distance (amplitude) of the vibration portion 28A of the air-blocking film 28 from the lining substrate 24, that is, the frequency of the sound wave to be absorbed, according to the interval between the adjacent fixing portions 30. It can be configured (details will be described later).

  Further, here, the roof lining 10 (lining base material 24) constituting the roof portion 14 is partitioned into unit sections Ri (i is a natural number) which are virtually a plurality of regions as shown in the bottom view in FIG. The frequency fi of sound waves to be absorbed is set for each unit section Ri. The setting of the frequency fi is required for each unit section Ri in order to suppress (minimize) the level of undesirable sound (noise) at the ear position of the passenger (driver, rear seat passenger, etc.) in the passenger compartment 25. Is set based on the required sound absorption performance. In this embodiment, the roof lining 10 is divided into a total of 24 unit sections Ri of 4 columns and 6 rows, and the dimensional shape of each unit section Ri is constant.

  In addition, the roof lining 10 is configured so as to absorb the sound of the frequency fi set as the absorption target for each unit section Ri, and for each unit section Ri, the interval between the fixing portions 30 of the air-blocking film 28 with respect to the lining substrate 24. Di is set. As a specific example, as shown in FIG. 5, the interval between the fixed parts 30 in the unit section R1 is D1, and the distance between the fixed parts 30 in the unit section R5 is D5, which is absorbed by the adjacent unit sections R1 and R5. The sound frequency is set to be different.

In this embodiment, the sound wave to be absorbed in each unit section Ri between the surface 24A (skin material 26) of the lining base material 24 and the portion where the maximum amplitude of the portion 28A between the fixing portions 30 in the air blocking film 28 is generated. The distance Di between the fixed portions 30 in each unit section Ri is set so that the distance Li along the assumed incident direction is 1/4 of the wavelength λi of the sound wave. That is, as shown in FIG. 6, in the roof lining 10, the portion where the maximum amplitude ai _{max of the} sound wave Si to be absorbed in each unit section Ri is substantially coincident with the surface 24 </ b> A (skin layer 26) of the lining substrate 24. In addition, the interval Di between the fixed portions 30 is set.

  For example, in the example of FIG. 6, in the unit section R1, the distance L1 along the assumed incident direction of the sound wave S1 between the surface 24A of the lining substrate 24 and the maximum amplitude part of the vibration part 28A of the ventilating film 28 is the sound wave S1. The interval D1 is set so as to be 1/4 of the wavelength λ1. In the unit section R5, the sound wave S5 between the surface 24A of the lining substrate 24 and the maximum amplitude portion of the vibration portion 28A of the air blocking film 28 is generated. The distance D5 is set so that the distance L5 along the assumed incident direction is 1/4 of the wavelength λ5 of the sound wave S5.

  As described above, in the roof lining 10, the sound absorption rate at each unit section Ri according to the frequency fi of the sound wave Si to be absorbed, in other words, at the frequency fi set for each unit section Ri as shown in FIG. 7. The fixed interval Di of the air-blocking film 28 with respect to the lining substrate 24 is set so that the following peak occurs.

  In addition, the peripheral edge part of the ventilation stopper film 28 is adhesively fixed to the peripheral edge part of the lining substrate 24 or the skin material 26 over the entire periphery, and between the ventilation stopper film 28 and the lining substrate 24 (surface 24B). The structure prevents dust and the like from entering.

  Next, the operation of this embodiment will be described.

  In the automobile 12 to which the roof lining 10 is applied, the engine noise transmitted to the passenger compartment 25 and the tire noise accompanying traveling are incident on each unit section Ri of the roof lining 10. Each unit section Ri of the roof lining 10 mainly absorbs the set frequency fi component of the incident noise.

  Here, in the roof lining 10, since the fixed interval Di of the air blocking film 28 with respect to the lining substrate 24 is set for each unit section Ri, the sound absorption characteristics required (different) for each unit section Ri can be changed by changing the fixed distance Di. It was realized to set in. Since the frequency component fi of the noise to be absorbed is different for each unit section Ri so as to reduce the noise at the passenger's ear position in the passenger compartment, the roof lining 10 in the passenger compartment at the passenger's ear position in the passenger compartment 25. Noise is significantly reduced.

  That is, the necessary performance, that is, the frequency fi of the sound wave to be absorbed is set for each unit section Ri of the roof lining 10 based on the occupant's ear position (one place or a plurality of places) so that the sound absorption coefficient peak occurs at the frequency fi. Since the fixed interval Di (the distance from the surface 24B of the air blocking film 28) of the air blocking film 28 with respect to the lining base material 24 is set for each unit section Ri, in other words, the roof lining 10 is a compartment of a specific automobile 12. Since the tuning is performed according to No. 25, it is possible to efficiently absorb the sound to be reduced with respect to the occupant's ear position.

  For example, in a simplified manner, a relatively low frequency booming noise tends to be a problem at the rear seat occupant's ear position (overhead). In this case, the fixed interval Di of the unit section Ri in the vicinity of the rear seat is set to be relatively wide. Low frequency sound is absorbed, and for example, high frequency transmitted sound is likely to be a problem at the ear position of the driver's seat. In this case, the fixed interval Di of the unit section Ri in the vicinity of the driver's seat is set relatively narrow to absorb the high frequency sound. Can be.

  Further, in the roof lining 10, it is not necessary to take measures to support a specific part of the roof lining 10 (ventilation film 28) on the roof panel 16 or the like directly through another member such as felt in order to tune the sound absorption characteristics. become.

  On the other hand, in the roof lining 10, since the ventilation from the surface 24B of the lining base material 24 is prevented by the ventilation stopper film 28, the skin material 26 is prevented from being stained.

  Thus, in the roof lining 10 according to the present embodiment, the sound absorption characteristic of each unit section Ri can be set according to the relationship with the occupant's ear position.

  In the above-described embodiment, the example in which the ventilating film 28 is fixed to the lining substrate 24 by point bonding is shown. However, the present invention is not limited to this, and for example, as shown in FIG. The fixing portions 32 by bonding may be arranged in a lattice shape, and the interval Di between the fixing portions may be different for each unit section Ri. Further, the fixing part 30 by point bonding and the fixing part 32 by line bonding are not limited to the configuration arranged in a rectangular shape or a lattice shape, and can be various arrangements such as a triangular arrangement and a hexagonal arrangement.

  In the above embodiment, an example in which the interval Di in the vehicle body front-rear direction of the fixing portion 30 of the ventilation stopper film 28 with respect to the lining base material 24 is set for each unit section Ri, but the present invention is not limited thereto. For example, an interval in the vehicle width direction may be set, and both the intervals in the longitudinal direction of the vehicle body and the vehicle width direction may be set for each unit section Ri.

  Furthermore, in the said embodiment, although the example which divided | segmented the roof lining 10 into 24 unit division Ri of the same dimension shape was shown, this invention is not limited to this, The unit division Ri has a dimension shape which a part or all differs. The unit section Ri may be set to be larger or smaller than 24.

  Furthermore, in the above embodiment, an example in which the vehicle sound absorbing material of the present invention is applied to the roof lining 10 is shown, but the present invention is not limited to this. For example, a waterproof sheet contacts a trim base material. It is also possible to apply the present invention to an interior material such as a door trim material and a sound absorbing member outside the vehicle compartment such as an engine undercover configured by contacting a surface acoustic wave reflector with a sound absorbing base material.

It is a sectional side view which expands and shows the roof lining which concerns on embodiment of this invention. It is a sectional side view which shows the vibration state of the ventilation film which comprises the roof lining which concerns on embodiment of this invention. 1 is a side sectional view showing an automobile to which roofing according to an embodiment of the present invention is applied. It is a bottom view which shows the virtual division of the roof lining which concerns on embodiment of this invention. It is a bottom view which shows the fixed pitch with respect to the lining base material of the ventilation stopper film which comprises the roof lining which concerns on embodiment of this invention. It is a typical sectional side view which shows the setting method of the space | interval between the fixed parts of the roof lining which concerns on embodiment of this invention. It is a diagram which shows the relationship between the frequency of the sound wave which should be absorbed of each unit division of the roof lining which concerns on embodiment of this invention, and a sound absorption factor. It is a bottom view which shows the modification of the fixing | fixed site | part with respect to the lining base material of the ventilation stopper film which comprises the roof lining which concerns on embodiment of this invention.

Explanation of symbols

10 roof lining (sound absorbing material for vehicles)
24 Lining substrate (Sound absorbing substrate)
28 Film (Surface acoustic wave reflector)
30 ・ 32 fixed part

Claims (5)

A sound absorbing material for a vehicle in which a surface acoustic wave reflector is placed in contact with a surface opposite to the incident side of the sound to be absorbed in the sound absorbing base material,
The planar sound wave reflector is partially fixed to the sound-absorbing substrate at a predetermined interval,
And the said predetermined space | interval between the fixing | fixed site | parts of the said planar sound wave reflector and the said sound-absorbing base material is each set for every unit division of the said sound-absorbing base material, The said predetermined space | interval differs in the adjacent unit division vehicle sound absorption material that have a.   The predetermined interval between the fixed portions of the surface acoustic wave reflector and the sound absorbing base material is set as an interval in which the planar sound wave reflector can be vibrated with contact with and separated from the sound absorbing base material between the fixed portions. The vehicle sound absorbing material according to claim 1.   The predetermined interval between the fixed portions of the surface acoustic wave reflector and the sound absorbing base material for each unit section is determined by the sound wave having a frequency determined for each unit section, and the surface acoustic wave between the fixed portions. The sound absorbing material for a vehicle according to claim 2, wherein the sound absorbing material for a vehicle according to claim 2 is set as an interval in which the reflector vibrates primarily with the sound absorbing substrate.   The predetermined interval for each unit section between the fixed portions of the planar sound wave reflector and the sound absorbing base material is set as an interval at which the peak of the sound absorption coefficient in each unit section occurs at a frequency determined for each unit section. The vehicle sound absorbing material according to claim 3.   The sound-absorbing base material has air permeability and is arranged so that the sound to be absorbed is incident from the vehicle interior side, and the planar sound wave reflector has air permeability and the vehicle in the sound-absorbing base material. The sound absorbing material for a vehicle according to any one of claims 1 to 4, wherein the sound absorbing material is in contact with a side opposite to the room side.

Images