JP2008037212A - Sound absorbing material for vehicle roof part, and sound absorbing structure of vehicle roof part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing material for vehicle roof part capable of absorbing the noise in a cabin in a range from a low/medium frequency to a high frequency without increasing thickness of the material. <P>SOLUTION: A plate-like sound absorbing material 7 comprises a first sound absorbing material part 10 provided on an outer peripheral part to absorb the noise of high frequencies and a second sound absorbing material part 11 singly provided on an inner peripheral side of the first sound absorbing material part 10 to absorb the noise of low/medium frequencies. The noise of high frequencies is absorbed on the outer peripheral part of a roof panel 5 by the first sound absorbing material part 10, and the noise of low/medium frequencies is absorbed on the inner peripheral side from the outer peripheral part of the roof panel 5 by the second sound absorbing material part 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sound absorbing material for a vehicle roof part and a sound absorbing structure for the vehicle roof part that can effectively absorb noise into a vehicle compartment during traveling.

  There are various types of vehicle interior noise reduction means for reducing vehicle interior noise during traveling. One of them is an active noise control device as shown in Patent Document 1. According to this active noise control device, the noise in the vehicle interior can be canceled and canceled by the secondary noise having the opposite phase to the noise, and the vehicle interior noise based on the low frequency road noise can also be silenced.

On the other hand, as another type of vehicle interior noise reduction means, there has been proposed a structure in which a sound absorbing material is provided on the roof panel portion in order to absorb noise entering the vehicle interior. A sound absorbing material suitable for such a structure, for example, as shown in Patent Document 2, it is a laminate of at least two layers, and each layer has a sound absorbing characteristic from a low frequency to a high frequency from the front surface layer toward the back surface layer. If what is set is applied, it is considered that vehicle interior noise in a wide range from low frequency to high frequency can be absorbed by the sound absorbing material.
JP 2000-322066 A JP 2001-306080 A

  However, the sound-absorbing material used in the above structure is a laminated body having a laminated structure. If the sound-absorbing characteristics are set over a wide frequency range, the number of laminated layers increases and the thickness increases vigorously. For this reason, when such a sound-absorbing material is used, the space above the head of the occupant is narrowed in the passenger compartment, and there is a risk of giving the occupant a feeling of pressure.

  Under such circumstances, the present inventors changed the viewpoint and studied, regarding the sound source of the cabin interior, where the sound pressure in the low / medium frequency region is large and where the sound pressure in the high frequency region is large. However, the location is different, and the location is on the outer periphery side of the roof panel for locations with high sound pressure in the high frequency region, and on the inner side of the outer periphery of the roof panel for locations with high sound pressure in the low and medium frequency regions. I found out.

The present invention has been made on the basis of such knowledge, and a first technical problem thereof is for a vehicle that can absorb vehicle interior sound in a range from low to medium frequencies to high frequencies without increasing the thickness. The object is to provide a sound absorbing material for a roof panel.
A second technical problem is to provide a sound absorbing structure for a vehicle roof part that can absorb a vehicle interior sound in a range from a low / medium frequency to a high frequency without narrowing the vertical space in the vehicle interior.

In order to achieve the first technical problem, in the present invention (the invention according to claim 1),
A plate-like sound absorbing material for a vehicle roof panel having an outline substantially along the roof panel of the vehicle,
A first sound-absorbing material part that is provided on the outer periphery and absorbs high-frequency sound in a sound range of 800 Hz to 10 kHz;
A second sound-absorbing material part that is provided independently on the inner peripheral side of the first sound-absorbing material part and absorbs low / medium frequency sound in a sound range of 100 Hz or more and less than 800 Hz;
Is provided as a configuration.

  With this configuration, if the sound absorbing material is installed in a state along the roof panel of the vehicle, the first sound absorbing material portion can be disposed on the outer peripheral side of the roof panel, and the second sound absorbing member is located on the inner side of the outer peripheral portion of the roof panel. Sound absorbing material parts can be arranged. Sound absorbing material parts suitable for sound absorption are arranged at locations where the sound pressure of each frequency is high, and only the sound absorbing material parts (one layer) can be used for high frequency sound, low Each medium frequency sound can be absorbed.

  According to a preferred aspect of the present invention, the first sound absorbing material portion includes at least a portion corresponding to one side in the vehicle width direction corresponding to one side in the vehicle width direction of the vehicle and the other side in the vehicle width direction of the vehicle. It is possible to adopt a configuration in which the vehicle is located in a portion corresponding to the other side in the vehicle width direction (corresponding to claim 2). With this configuration, it is possible to reliably and effectively absorb high-frequency sound propagating from a gap such as a weatherstrip (opening / closing window glass gap) using the sound absorbing material.

  As a preferred aspect of claim 1, the second sound absorbing material portion is between the portion corresponding to one side in the vehicle width direction and the portion corresponding to the other side in the vehicle width direction. The structure located in the state adjacent to can be taken (corresponding to claim 3). With this configuration, it is possible to reliably and effectively absorb low / medium frequency sound based on vibration from the road surface side and the like using the sound absorbing material. In particular, a sound absorbing space is formed between the roof panel and the plate material by disposing a plate material opposite to the roof panel, so that the direction in which the low / medium frequency sound (wave) propagates to the passenger compartment travels is determined. Under the structure that changes to the direction along the plate material (a phenomenon found by the present inventor), with respect to the low and medium frequency sound waves in the sound absorbing space, the belly part with the largest particle velocity is inward in the vehicle width direction. Therefore, the sound absorption performance of low / medium frequency sound can be enhanced.

  As a preferred aspect of claim 1, the first sound absorbing material portion may have a configuration in which a length larger than 1/8 times a wavelength of 10 kHz is secured with respect to a length in a direction along the plate surface. Yes (corresponding to claim 4). With this configuration, a plate material is disposed opposite to the roof panel to form a sound absorbing space between the roof panel and the plate material, and the direction in which the high-frequency sound (wave) travels is along the plate material in the sound absorbing space. Under the structure, by arranging the sound absorbing material in the sound absorbing space along the roof panel, the high frequency sound in the sound absorbing space can be obtained by using the first sound absorbing material portion for the belly portion having the largest particle velocity. The sound absorption performance of high frequency sound can be enhanced.

  As a preferred aspect of claim 1, the second sound absorbing material portion may have a configuration in which a length larger than １ ／ times the wavelength of 799 Hz is secured with respect to the length in the direction along the plate surface. Yes (corresponding to claim 5). With this configuration, a plate material is disposed opposite to the roof panel to form a sound absorption space between the roof panel and the plate material, and the direction in which the low / medium frequency sound (wave) travels follows the plate material in the sound absorption space. If the sound absorbing material is arranged along the roof panel in the sound absorbing space under the structure that changes the direction, the second part of the belly portion having the highest particle velocity is related to the low / medium frequency sound in the sound absorbing space. Can be taken in by the sound absorbing material portion, and the sound absorbing performance of low and medium frequency sounds can be enhanced.

In order to achieve the second technical problem in the present invention (the invention according to claim 6),
In the sound absorbing structure of the vehicle roof part in which the sound absorbing material is arranged on the lower surface side of the roof panel,
The sound absorbing material comprises a first sound absorbing material disposed on the outer peripheral side of the roof panel, and a second sound absorbing material disposed independently on the inner peripheral side rather than the outer peripheral side of the roof panel,
The first sound absorbing material is set to have a characteristic of absorbing high frequency sound in a sound range of 800 Hz to 10 kHz,
The second sound absorbing material is configured to have a characteristic of absorbing low / medium frequency sound in a sound range of 100 Hz to less than 800 Hz.

  With this configuration, sound absorbing materials suitable for sound absorption can be placed at locations where the sound pressure at each frequency is high, and high-frequency sounds and low / medium frequency sounds can be absorbed by each sound-absorbing material (one layer). become.

  According to a preferred aspect of the present invention, a plate material is disposed opposite to the roof panel to form a sound absorbing space between the roof panel and the plate material, and the first sound absorbing material and the second sound absorbing space are formed in the sound absorbing space. It is possible to adopt a configuration in which the sound absorbing material is disposed (corresponding to claim 7). With this configuration, high-frequency sound generated on the outer peripheral side of the roof panel can be effectively absorbed by the first sound-absorbing material. On the other hand, with regard to low / medium frequency sound transmitted to the passenger compartment, the traveling direction of the wave is determined in the sound-absorbing space. Thus, by changing the direction along the plate material, the belly portion having the largest particle velocity can be positioned on the inner side in the vehicle width direction, and low and medium frequency sounds can be effectively absorbed by the second sound absorbing material.

  As a preferable aspect of claim 6, it is possible to adopt a configuration in which the first sound absorbing material and the second sound absorbing material are formed as a plate-like integrated product (corresponding to claim 8). With this configuration, the handleability of the sound absorbing material can be improved when the structure is assembled.

According to the present invention (the invention according to claim 1), the sound absorption for a vehicle roof portion that can effectively absorb the vehicle interior sound in the range of low / medium frequency to high frequency without increasing the thickness by using a laminated structure. Can provide material.
In addition, according to the present invention (the invention according to claim 6), it is possible to provide a sound absorption structure for a vehicle roof portion that can absorb sound in a vehicle compartment in a range from low to medium frequencies to high frequencies without narrowing the upper and lower spaces in the vehicle interior. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the sound absorbing structure of the vehicle roof part according to the embodiment will be described. As shown in FIG. 1, a vehicle compartment 3 is defined in the vehicle body 2 of the vehicle 1, and a roof trim 4 as a plate material is disposed above the vehicle compartment 3 in order to interior the vehicle compartment 3. . Although the roof trim 4 has a certain degree of hardness, the roof trim 4 is set so as to vibrate slightly due to the low-frequency sound propagated in the passenger compartment 3. The roof trim 4 is disposed substantially along the roof panel 5, and a sound absorbing space 6 is formed between the roof panel 5 and the roof trim 4 at the upper side of the passenger compartment 3. Yes.

  In the sound absorbing space 6, a sound absorbing material 7 is installed as shown in FIG. The sound-absorbing material 7 has a plate-like shape having an outline substantially along the roof panel 5 and the roof trim 4 (roof portion) (illustrated in FIG. 1 and FIG. 6 described later). Based on this, the sound absorbing material 7 is in a state in which the sound absorbing space 6 extends along substantially the entire roof panel 5 and roof trim 4. As shown in FIG. 2, the sound absorbing material 7 basically has a phenomenon in which when the sound enters the sound absorbing space 6, the particle velocity of air particles is distributed along the roof trim 4 in the sound absorbing space 6 ( Utilizing the knowledge found by the present inventor: already disclosed in Japanese Patent Application No. 2006-40695), the function of absorbing the sound is to be achieved. At this time, the roof trim 4 slightly vibrates due to the transmission of sound from the inside of the passenger compartment 3, and the particle velocity in the sound absorbing space 6 increases (knowledge discovered by the present inventor: Japanese Patent Application 2006-2006). (Already disclosed in 40695), the sound absorbing effect of the sound absorbing material 7 is enhanced by using this.

  The sound absorbing material 7 has a structure different from the conventional one based on the knowledge found by the present inventors. First, the knowledge will be described. The present inventor relates to a sound source in the passenger compartment 3 where the sound pressure in the low / medium frequency (100 Hz or more and less than 800 Hz) region is large, and where the sound pressure in the high frequency (800 Hz or more and 10 kHz or less) region is large. However, the location is different, and the location is inward of the outer periphery of the roof panel 5 at a location where the sound pressure in the high frequency region is large, and is inward from the outer periphery of the roof panel 5 at the location where the sound pressure in the low / medium frequency region is large. I found out that the side. This is a result obtained by the inventor of the present invention by conducting an experiment focusing on the following points.

For low and medium frequency sounds,
1) As shown in FIG. 1, vibrations (road noise: indicated by symbol a in FIG. 1) received from the road surface when traveling on a rough road surface are transmitted from the tire 15 via the suspension 9 to the vehicle body 2 (particularly corresponding portions). In FIG. 1 is indicated mainly by low / medium frequencies.
2) The vibration propagated to the vehicle body 2 is propagated into the passenger compartment 3 and enters the sound absorbing space 6 between the roof panel 5 and the roof trim 4 from the roof trim 4 (plate material). 3 changes in a direction along the surface of the roof trim 4 as shown in FIG. 3 (particle velocity is indicated by SVL in FIG. 3), and the belly portion having the largest particle velocity is within the vehicle width direction. Located on the other side (see SVL in FIG. 3),
3) On the other hand, even if high-frequency sound enters the sound absorbing chamber 3 from the passenger compartment 3, as shown in FIG. 4, high-frequency sound (in FIG. 4, the particle velocity in high-frequency sound is indicated by SVH). Is short (in FIG. 4, the wavelength is relatively large for illustration), and the sound pressure of high-frequency sound does not increase at a specific location,
4) Furthermore, the vibrations propagated to the vehicle body 2 resonate with each other in the passenger compartment 3, but when the resonance occurs, the particle velocity of the air particles at the wall is small.
Focusing on these phenomena, the part where the sound pressure (dB) of the low / medium frequency sound increases is the entire area in the front-rear direction of the passenger compartment 3 and the inner side of the roof panel 5 in the vehicle width direction. An estimation was performed, and an experiment was performed under the assumption. Under 400 Hz (low / medium frequency), the above estimation was obtained. This low / medium frequency sound generation region is indicated by a Slm region surrounded by a one-dot chain line in FIG.

On the other hand, for high frequency sound,
1) Wind noise is central,
2) One of the wind noises is considered to be based on air swirl, and the air swirl Wr that generates wind noise is generated in a place where the shape of the vehicle 1 is changed as shown in FIG. thing,
3) As another type of wind noise, a sucking sound when air is sucked out from the inside of the passenger compartment 3 based on a pressure difference between the inside and outside of the passenger compartment 3 during traveling can be considered. That it is considered that the flow We of the air is generated at the door seal part,
In consideration of the above, it was estimated that the portion where the sound pressure (dB) of the high-frequency sound is increased is the outer peripheral portion of the roof panel 5, and an experiment was conducted under the assumption, and the result was 1200 Hz (high frequency). Below, it was shown that the places where the sound pressure (dB) is large are the outer peripheral portion of the roof panel 5, particularly on both sides in the vehicle width direction of the roof panel having many door seal portions. This high frequency sound generation region is indicated by a Sh region surrounded by a one-dot chain line in FIG.

  Based on such knowledge, in this embodiment, the sound absorbing material 7 is produced as follows. As shown in FIG. 7, the sound absorbing material 7 is configured integrally with a first sound absorbing material portion 10 and a second sound absorbing material portion 11 under a plate-like rectangular shape (illustrated simply). They occupy a predetermined area in the sound absorbing material 7 with a single layer having a predetermined thickness. The first sound absorbing material portion 10 has a characteristic of absorbing high frequency sound (800 Hz to 10 kHz). As long as the first sound absorbing material portion 10 has a sound absorbing characteristic of high frequency sound, an existing sound absorbing material portion 10 is provided. What is included (for example, natural fibers such as wool and cotton, and those made of general materials such as synthetic fibers such as polyethylene terephthalate (PET) and polypropylene (PP)) Can also be used. In the present embodiment, as shown in FIG. 7, the first sound absorbing material portion 10 includes a front portion 10 f corresponding to the front portion of the roof panel 5 and a rear portion corresponding to the rear portion of the roof panel 5. 10 b, located on both side portions 10 s corresponding to both side portions of the roof panel 5 in the width direction, and formed over the entire outer peripheral portion of the sound absorbing material 7, and the sound absorbing material 7 is properly disposed in the sound absorbing space 6. In this state, the first sound absorbing material portion 10 is located on the outer peripheral portion of the roof panel 5. The first sound-absorbing material portion 10 is at least 1/8 times as long as the wavelength of the high-frequency sound in the direction along the plate surface of the sound-absorbing material 7 (more preferably 1/4 times the wavelength of the high-frequency sound. A length of 6 cm (in this embodiment, 1/8 wavelength of a wavelength of 800 Hz) or more is secured. In FIG. 7, Sh-1, Sh-2, Sh-3 are secured. In any case, a length of 6 cm or more is secured. This is because, when the sound absorbing material 7 is disposed in the sound absorbing space 6 so that the plate surface thereof is along the roof panel 5 and the roof trim 4 (roof panel portion), high-frequency sound enters the sound absorbing space 6. In this case, an antinode portion of the wave having the largest particle velocity (energy) (an antinode portion when expressed in a wave shape) is taken in by the first sound absorbing member 10 to improve the sound absorbing performance of the high frequency sound.

  The second sound absorbing material part 11 has a characteristic of absorbing low / medium frequency sound (100 Hz to less than 800 kHz), and the second sound absorbing material part 11 has a sound absorbing characteristic of low / medium frequency sound. As long as it has, the existing one (for example, the one that is softened so that the amount of air passing through the sound absorbing material for absorbing high-frequency sound, or the one shown in JP 2001-306080 A) is used. Anything can be used, including As shown in FIG. 7, the second sound absorbing material portion 11 is disposed adjacent to the region surrounded by the first sound absorbing material portion 10, and the sound absorbing material 7 is appropriately disposed in the sound absorbing space 6. In this state, the second sound absorbing material portion 11 is located on the inner side in the vehicle width direction of the roof panel 5 over substantially the entire front-rear direction in the passenger compartment 3. The second sound-absorbing material portion 11 is at least a length of 1/8 times the wavelength of the low / medium frequency sound with respect to the direction along the plate surface of the sound absorbing material 7 (more preferably, 1 of the wavelength of the low / medium frequency sound). / 4 times or more), specifically, a length of 43 cm (in this embodiment, 1/8 wavelength of a wavelength of 100 Hz) or more is secured, and Slm-1 and Slm-2 in FIG. In any case, a length of 43 cm or more is secured. This is because when the sound absorbing material 7 is disposed in the sound absorbing space 6 so that the plate surface thereof is along the roof panel 5 and the roof trim 4 (roof panel portion), the sound absorbing space 6 has a low / medium circumference. When wave sound enters, the second sound-absorbing material part 11 takes in the anti-wave part of the wave with the largest particle velocity (energy) (the anti-node part when expressed in a wave shape) to enhance the sound absorption performance of low and medium frequency sound. It is going to be.

  Therefore, in such a structure, high-frequency sound entering the sound absorbing space 6 from the roof panel, door seal portion (weather strip gap), etc., on both sides in the vehicle width direction of the roof panel 5 where the sound pressure is high. The first sound absorbing member 10 effectively absorbs sound, and the low / medium frequency sound entering the sound absorbing space 6 from the road surface via the interior of the vehicle compartment 3 is a region where the sound pressure is high. In the region surrounded by the single sound absorbing material 7 (substantially the entire vehicle body 2 in the vehicle compartment 3 in the front-rear direction and inward in the vehicle width direction), the second sound absorbing material portion 11 effectively absorbs sound. For this reason, even when absorbing sound over a wide frequency range, it is not necessary to laminate a sound absorbing material portion having a characteristic of absorbing sound in other frequency regions in each sound absorbing material portion. Based on the laminated structure of the material 7, it can prevent that the thickness increases. As a result, the space above the occupant can be prevented from becoming narrow due to the separation of the roof trim 4 from the roof panel 5 to the vehicle compartment 3 lower side.

  In the present embodiment, the sound absorbing material 7 is an integrated body of the first and second sound absorbing materials 7, but the first sound absorbing material portion 10 and the second sound absorbing material portion 11 are independent of each other. The first sound-absorbing material 10 and the second sound-absorbing material 11 may be used, and they may be disposed individually. Accordingly, the first sound absorbing material 10 and the second sound absorbing material 11 can be appropriately disposed while taking into consideration the internal structure of the roof panel 5.

8 and 9 show experimental results of sound absorption performance for various sound absorbing materials. The experiment was conducted by arranging various sound absorbing materials in the sound absorbing space 6 and running on a coarse grain road at 60 km / h, in the vicinity of the driver's ear position, low / medium frequency sound 100 Hz to 799 Hz, high frequency sound 1000 Hz. Each sound pressure of ˜5000 Hz was measured.
In this case, as an experiment mode of various sound absorbing materials, when no sound absorbing material is provided, when only one sound absorbing material 10 for high frequency sound is provided as shown in FIG. 10, further lower / medium frequencies are provided as shown in FIG. When only the sound absorbing material 11 for sound is provided, as shown in FIG. 12, the sound absorbing material 10 for low frequency and medium frequency sound and the sound absorbing material 10 for high frequency sound have a two-layer structure, and the sound absorbing material 10 for high frequency sound is on the upper side. As shown in FIG. 13, the high frequency sound absorbing material 10 is arranged on both sides (window side) in the vehicle width direction, while the low and medium frequency sound absorbing material 11 is arranged between them. A case of use (Example of the present invention) was prepared. Moreover, as the sound absorbing material 11 for low / medium frequency sound used in various sound absorbing materials, a material having a flow resistance of 10,000 (N · S / m ⁴ ) or less (relatively improved sound absorbing characteristics of low / medium frequency sound) As a sound absorbing material for high frequency sound used in various sound absorbing materials, a flow resistance of 100,000 to 1,000,000 (N · S / m) that relatively improves the sound absorbing characteristics of high frequency sound. Those within the range of ⁴ ) (predetermined values) were used.

  Although the experimental results showed the best sound absorption performance when using only the sound absorbing material for low / medium frequency sound for the low / medium frequency sound, then the present invention example showed excellent sound absorption performance, In the present invention, when only the other high-frequency sound absorbing material 10 is used, it is better than the case of using the two-layer structure of the low / medium frequency sound absorbing material 11 and the high frequency sound absorbing material 10. Showed a good result. On the other hand, with respect to the high frequency sound, although it is slight, the example of the present invention shows a better result than the case of only the high frequency sound absorbing material 10 alone, and shows the best result as the sound absorbing performance. It was. This is considered as follows. High frequency sound outside the vehicle does not occur so much on the inner side in the vehicle width direction of the roof panel 5 and does not cause a problem (the type of the sound absorbing material does not make a difference), but on the both sides of the roof panel 5 in the vehicle width direction. Although it occurs, it is more effective due to the characteristics of the sound absorbing material 10 for high frequency sound (property of transmitting high frequency sound) in both the case of the one more high frequency sound absorbing material 10 and the example of the present invention. Sound insulation will occur. On the other hand, with respect to the high-frequency sound included in the sound in the vehicle interior 3 (basically, most of the vehicle interior sound is low / medium frequency sound), only the sound absorbing material 10 for higher frequency sound is used. In the case of the present invention, the high frequency sound is reflected to the vehicle interior 3 side on the inner side in the vehicle width direction of the roof panel 5 that occupies most, based on the nature thereof. The sound absorbing material 11 for medium frequency sound is considered to absorb some high frequency sound. For this reason, as described above, although it is a slight difference, it is considered that the example of the present invention shows a better result than the case of only the higher frequency sound absorbing material 10. Thus, it was confirmed that using the example of the present invention is most suitable for absorbing sound over a wide frequency range from low / medium frequency sound to high frequency sound.

Explanatory drawing explaining the sound absorption structure of the vehicle roof part which concerns on embodiment. Explanatory drawing explaining the sound absorption by a sound-absorbing material. Explanatory drawing explaining the state of the low / medium frequency sound in the sound absorption space when the low / medium frequency sound enters the sound absorption space from the passenger compartment. Explanatory drawing explaining the state of the high frequency sound in the sound absorption space when a high frequency sound enters into the sound absorption space from the vehicle interior. Explanatory drawing explaining the condition where a high frequency sound arises in the vehicle width direction both sides of a roof panel. The figure which shows the area | region where each sound pressure of a low / medium frequency sound and a high frequency sound is high in a vehicle planarly. The perspective view which shows the sound-absorbing material which concerns on embodiment. The figure which shows the sound absorption performance result of the various sound-absorbing materials about the low and middle frequency sound. The figure which shows the sound absorption performance result of the various sound-absorbing materials about a high frequency sound. The figure which shows typically the sound absorbing material for one layer of high frequency sound. The figure which shows typically the sound-absorbing material for one layer of low and medium frequency sound. The figure which shows typically the sound-absorbing material made into the two-layer structure of the sound-absorbing material for low and medium frequency sound, and the sound-absorbing material for high frequency sound. The figure which shows typically the sound-absorbing material which concerns on the example of this invention.

Explanation of symbols

1 vehicle 3 vehicle compartment 4 roof panel trim (plate material)
5 roof panel 6 sound absorbing space 7 sound absorbing material 10 first sound absorbing material portion 10s side portion (part corresponding to one side in the vehicle width direction, portion corresponding to the other side in the vehicle width direction)
11 Second sound-absorbing material part

Claims (8)

A plate-like sound absorbing material for a vehicle roof panel having an outline substantially along the roof panel of the vehicle,
A first sound-absorbing material part that is provided on the outer periphery and absorbs high-frequency sound in a sound range of 800 Hz to 10 kHz;
A second sound-absorbing material part that is provided independently on the inner peripheral side of the first sound-absorbing material part and absorbs low / medium frequency sound in a sound range of 100 Hz or more and less than 800 Hz;
Equipped with,
A sound absorbing material for a vehicle roof part. In claim 1,
The first sound-absorbing material portion is at least one portion corresponding to one side in the vehicle width direction corresponding to one side in the vehicle width direction and the other side in the vehicle width direction corresponding to the other side in the vehicle width direction. Located in the corresponding parts,
A sound absorbing material for a vehicle roof part. In claim 2,
The second sound absorbing material portion is positioned between the portion corresponding to one side in the vehicle width direction and the portion corresponding to the other side in the vehicle width direction in a state adjacent to the first sound absorbing material portion of the corresponding portions. Yes,
A sound absorbing material for a vehicle roof part. In claim 1,
The first sound-absorbing material part has a length greater than 1/8 times the wavelength of 10 kHz with respect to the length in the direction along the plate surface.
A sound absorbing material for a vehicle roof part. In claim 1,
The second sound-absorbing material part has a length that is greater than 1/8 times the wavelength of 799 Hz with respect to the length in the direction along the plate surface.
A sound absorbing material for a vehicle roof part. In the sound absorbing structure of the vehicle roof part in which the sound absorbing material is arranged on the lower surface side of the roof panel,
The sound absorbing material comprises a first sound absorbing material disposed on the outer peripheral side of the roof panel, and a second sound absorbing material disposed independently on the inner peripheral side rather than the outer peripheral side of the roof panel,
The first sound absorbing material is set to have a characteristic of absorbing high frequency sound in a sound range of 800 Hz to 10 kHz,
The second sound absorbing material is set to have a characteristic of absorbing low / medium frequency sound in a sound range of 100 Hz or more and less than 800 Hz,
A sound absorbing structure for a vehicle roof portion. In claim 6,
A plate material is disposed opposite to the roof panel to form a sound absorbing space between the roof panel and the plate material,
The first sound absorbing material and the second sound absorbing material are disposed in the sound absorbing space.
A sound absorbing structure for a vehicle roof portion. In claim 7,
The first sound absorbing material and the second sound absorbing material are formed as a plate-like integrated object,
A sound absorbing structure for a vehicle roof portion.

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