JP2006160177A - Sound absorbing structure of automobile running on road - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost automobile running on the road capable of enhancing the calmness in running by lessening the intruding sound to the ears of the occupant effectively while a good design and good safety are assured. <P>SOLUTION: A recess 23 is formed to the cabin side over the seating surface 73a with respect to an interior base material 22 as the side face when viewed by an occupant seated on the seating part 73, and a sound absorbing material able to absorb sounds is embedded in the recess 23 so as to form a sound absorbing structure ST1. Example of the interior base material to form the sound absorbing structure is a door trim interior material and a pillar garnish interior material. It may also be accepted that a hollow sound absorbing material 126 furnished with through holes 127 tying the cabin side to the extra-vehicle side. It may be accepted that the diameter of the through holes 127 in the hollow sound absorbing material is made 1-5 mm and the total area of the projected areas of the holes relative to the projected area of the hollow sound absorbing material when projected from the cabin side to the extra-vehicle side is made 2-30 %. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sound absorbing structure for a road traveling vehicle in which an interior base material is provided on a vehicle compartment side with respect to a vehicle body panel.

In general, a body of a road vehicle is formed by press-molding and welding a plurality of panels to form an outer shape of the vehicle and forms various vehicle interior spaces such as a passenger compartment, an engine compartment, and a cargo compartment. . This body is generally formed by welding a panel on the outside of the vehicle called an outer panel and a panel on the side of the vehicle called an inner panel, with a space therebetween. The reason for the space between the panels is to increase the rigidity of the vehicle body by increasing the apparent cross-sectional area without increasing the weight.
The body configured as described above is dipped in a rust preventive liquid to be primed, dried in a heating furnace, and then painted a plurality of times to finish. Thereafter, various functional parts are mounted on the body, and various interior materials are laid and finished on the interior side of the body so as to cover the inner panel. The reason why the interior material is laid is to provide a design decoration, to improve the tactile sensation, to provide sound absorption, and to ensure the safety of the passenger.
Generally, interior materials are made by coating a thin-walled thermoplastic resin base material with excellent heat moldability with a designable skin material, and the interior base material is molded into a three-dimensional shape along the inner panel at the laying position. Then, it is laid by being engaged with the inner panel by an engaging tool such as a resin clip.

  As described above, in the body of a road-traveling automobile, there are many places where a space is provided between the outer panel and the inner panel and is hollow, and the automobile is Various noises such as road noise, engine noise, wind noise, etc. that are generated when traveling on the road propagate in the cavity and leak to the passenger room where the passenger is seated via the inner panel, or adjacent to the passenger room It reaches the passenger compartment via the cargo compartment, engine compartment, etc., and is an obstacle to improve the comfort of the passenger compartment. For this reason, various proposals have been made to ensure sound absorption and sound insulation with a laying material laid on the vehicle interior side so as to enhance the quietness of the passenger compartment.

Patent Document 1 discloses that a pillar garnish having a hollow portion formed into a planar shape and molded from a synthetic resin is used, and that sound insulation is obtained by a hollow portion that is completely closed.
Patent Document 2 describes that a noise reduction assembly package including a hard layer having a microporous is fixed on a flat planar vehicle body part for sound insulation.
JP-A-6-286530 Special Table 2000-516175 JP 2002-356184 A

The inventor of the present application analyzed the sound field environment in the passenger compartment of a road vehicle and analyzed the noise transmitted to the passenger's ear position in the passenger compartment, particularly in the passenger compartment, for each part of the vehicle body panel. It was found that there are parts where noise from outside the vehicle is easy to propagate and parts where noise from outside the vehicle is difficult to propagate. Even if the techniques described in Patent Literatures 1 and 2 are applied to a vehicle body panel that easily propagates noise from outside the vehicle, the transmitted sound is larger than the noise is blocked, such as road noise entering the passenger's ear The intrusion sound could not be reduced effectively.
In the technique described in Patent Document 1, intrusion sound waves such as road noise that have entered the vehicle interior are reflected by the surface on the vehicle interior side of the pillar garnish, and the reflected sound waves enter the passenger's ears. It is presumed that the intrusion sound that has been lost is not reduced.
In the technique described in Patent Document 2, since it is necessary to fix the noise reduction assembly package on a flat planar body part, it is necessary to fix the assembly package to the entire surface of the vehicle interior from the viewpoint of obtaining a good design. The material cost of the package is high, and the work for installing the assembly package takes time, and the cost for this work is also high. Therefore, there is room for examination from the viewpoint of cost reduction.

The technique described in Patent Document 3 is a technique for a work vehicle that is different from a road traveling vehicle, and cannot be applied to the present invention. In the same document, as shown in FIG. 4 of the same document, a sound absorbing sheet is constructed by laying a sound absorbing material under a step mat having a large number of holes, and the sound absorbing sheet is laid in a portion of the room excluding the window portion. Or it is affixed to obtain a silencing effect. However, since the sound absorbing sheet is provided on the entire room surface excluding the window, the material cost of the sound absorbing sheet is high, and the work for installing the sound absorbing sheet takes time, and the cost for this work is also high. Therefore, there is room for examination from the viewpoint of cost reduction.
Further, in this document, a resonance chamber that requires a space portion independent of the cabin is provided on the ceiling wall portion in the cabin of the work vehicle, and pipes are further communicated from the resonance chamber into the cabin. It is described that a resonance frequency component is attenuated and reduced by frictional resistance with surroundings in engine noise diffusing in the interior to obtain a silencing effect. However, as shown in FIGS. 9 to 12 of the same document, the resonance chamber is attached as a separate member to the ceiling wall portion, so that it is designed and safe for road vehicles especially for high-speed traveling. There is room for examination from the viewpoint of sex.

  The present invention has been made in view of the above problems, and effectively obtains intrusion sounds such as road noise and wind noise that enter the occupant's ear while obtaining a good design and good safety at low cost for road vehicles. The purpose is to reduce the noise and improve the quietness during running.

In order to achieve the above object, the present invention provides a road traveling vehicle in which an interior base material is provided on a vehicle compartment side with respect to a vehicle body panel and a seat having a seating portion whose upper surface is a seating surface of an occupant is provided in the vehicle interior. It has a sound absorbing structure, and a recess is formed on the vehicle interior side above the seating surface with respect to the interior base material that is a side as viewed from the occupant seated in the seating portion, and sound can be absorbed in the recess It is characterized in that a sound absorbing material is embedded.
The sound absorbing material embedded in the recess formed above the seating surface with respect to the interior base material that is the side as seen from the occupant seated in the seating part attenuates the sound, such as road noise that has entered the vehicle interior The intrusion sound is efficiently absorbed and reduced at a position close to the passenger's ear on the side of the passenger. This eliminates the need to install the sound absorbing material over the entire surface of the vehicle interior, thereby reducing the material cost of the sound absorbing material and eliminating the need to install the sound absorbing material over the entire surface of the vehicle interior. Can also be reduced. Furthermore, since the sound absorbing material is inserted into the recess of the interior base material, a good design is obtained and the safety is also good. Therefore, intrusion sounds such as road noise and wind noise that enter the passenger's ear can be effectively reduced while obtaining a good design and good safety at low cost.

  The interior base material that is the side as viewed from the occupant seated on the seating portion is a member provided on at least one of the door trim interior material and the pillar garnish interior material, and is above the seating surface with respect to the interior base material. In this case, the recess may be formed on the vehicle compartment side. When the sound field analysis of a road armored car was conducted, there was a gap in the door trim interior material and pillar garnish interior material, and noise from outside the vehicle propagated through this gap and entered the passenger compartment, and the passenger's ears. Was found to be transmitted to. By providing the hollow part or the sound absorbing material in the door trim interior material or the pillar garnish interior material, it is possible to improve sound absorption and improve quietness during traveling.

  When the sound-absorbing material is a porous sound-absorbing material, the intruding sound enters the fine holes of the sound-absorbing material and is diffusely reflected, and the energy of the intruding sound is attenuated, so that good sound absorbing properties can be obtained.

  The sound absorbing material may be configured as a perforated sound absorbing material in which a through hole that connects the passenger compartment side and the vehicle outer side opposite to the passenger compartment side is formed. When a test was performed using a perforated sound absorbing material, it was found that a better sound absorbing property was obtained. This is presumably because the intrusion sound enters the through hole and is repeatedly reflected, and the energy of the intrusion sound is attenuated.

  The perforated sound-absorbing material is a sound-absorbing material that does not have a through hole that connects the vehicle compartment side and the vehicle exterior side, and has a sound absorption characteristic that does not cause a peak at a frequency of 400 to 4000 Hz. It is good also as a structure made into the sound-absorbing material which formed the through-hole which connects a vehicle and the vehicle outer side with the diameter of 1-10 mm. Even if the material having the sound absorption characteristic has a sound absorption characteristic that does not cause a peak at a frequency of 400 to 4000 Hz, a peak of the sound absorption characteristic occurs at a frequency of 400 to 4000 Hz by forming a through hole having a diameter of 1 to 10 mm. Good sound absorption is obtained in a wide frequency range. As a result, the sound absorption is improved in a wider frequency range than in the case where sound is absorbed by the sound absorbing material in which the through hole connecting the passenger compartment side and the vehicle exterior side is not formed.

  The perforated sound absorbing material may be formed of at least one of a material obtained by foaming synthetic resin and a material obtained by collecting synthetic fibers. Then, good sound absorption is obtained.

The perforated sound-absorbing material has a density of 0.25 to 0.40 g / cm ³ and a sound-absorbing material in which a plurality of through-holes connecting the vehicle compartment side and the vehicle exterior side are formed with a diameter of 1 to 10 mm. It is good also as composition which has. Then, good sound absorption is obtained for the perforated sound absorbing material, the shape is sufficiently maintained, and good hardness is obtained.

  A plurality of through holes are formed in the perforated sound absorbing material, and the thickness of the perforated sound absorbing material in the direction connecting the vehicle compartment side and the vehicle outer side is equal to or less than the depth of the concave portion and 3 mm or more, The total area of the projected area of the through hole relative to the projected area of the perforated sound absorbing material when projected from the passenger compartment side to the vehicle exterior side may be 2 to 30%. As a result, good sound absorption is obtained, and good rigidity is obtained for the perforated sound absorbing material.

The sound absorbing material is at least one of a material in which a synthetic resin is foamed and a material in which synthetic fibers are aggregated without forming a through hole that connects the vehicle interior side and the vehicle exterior side opposite to the vehicle interior side. And a density of 0.02 to 0.25 g / cm ³ . In the case of using a holeless sound absorbing material in which a through hole connecting the passenger compartment side and the vehicle outer side is not formed, good sound absorbing properties can be obtained and good hardness can be obtained for the sound absorbing material.
The sound absorbing material may have a shore hardness of 10 to 70 according to a spring type hardness tester C type. Also by this, when using a sound absorbing material without holes, good sound absorbing properties can be obtained, and good hardness can be obtained for the sound absorbing material.

A skin material that closes the opening of the concave portion is installed on the interior side of the interior base material, and the skin material may have an air permeability of 6 cc / cm ² / sec or more according to JIS L1096. Good. Since the air permeability of the skin material is sufficiently large, the sound absorption by the sound absorbing material does not deteriorate.

According to the invention according to claim 1, for road vehicles, it is possible to effectively reduce intrusion sounds such as road noise and wind noise entering the passenger's ear while obtaining good design and good safety at low cost, It is possible to improve the quietness during traveling.
In the invention according to claim 2, it is possible to improve the sound absorption effect and further improve the quietness during traveling.
In the invention according to claim 3, it is possible to improve the sound absorption.

In the invention according to claim 4, it is possible to further improve the sound absorption.
In the invention according to the fifth aspect, it is possible to obtain good sound absorption in a wide frequency range.
In the invention concerning Claim 6, the perforated sound-absorbing material from which a favorable sound-absorbing effect is acquired can be provided.

In the invention according to claim 7, it is possible to obtain a good sound absorbing effect with a perforated sound absorbing material having a sufficient hardness and having a sufficient shape.
In the invention according to the eighth aspect, it is possible to obtain a good sound absorbing effect with a perforated sound absorbing material having a good rigidity.
In the invention according to the ninth and tenth aspects, it is possible to obtain a good sound absorbing effect with a holeless sound absorbing material having a good hardness.
In the invention concerning Claim 11, it becomes possible to improve the designability in a vehicle interior, without reducing the sound absorption effect.

Hereinafter, embodiments of the present invention will be described in the following order.
(1) Configuration of sound absorbing structure of road-traveling automobile:
(2) Action and effect of sound absorption structure of road-traveling automobile:
(3) Second embodiment:
(4) Example:
(5) Modification:

(1) Configuration of sound absorbing structure of road-traveling automobile:
FIG. 1 is a side view showing the main part of the interior of a road traveling vehicle 100 employing the sound absorbing structure ST1 according to the first embodiment of the present invention. FIG. 2 shows the main part of the driver's seat door 10 shown in FIG. FIG. 3 is a vertical cross-sectional view seen from the position A1-A1, and FIG. 3 is a front view schematically showing a noise intrusion route from the outside of the vehicle by partially cross-sectionally showing the main part of the on-road vehicle 100.
In the driver's seat door 10 of the present automobile, an interior base material 22 is provided on the vehicle interior side with respect to the vehicle body panels 12 and 14, and a recess 23 is formed on the vehicle interior side with respect to the interior base material 22. The sound absorbing structure ST <b> 1 of the present automobile has a recess 23 formed on the vehicle interior side above the seating surface 73 with respect to the interior base material 22 that is a side as viewed from the occupant seated on the seating portion 73. A sound absorbing material 26 capable of absorbing sound is embedded and configured.

The main road traveling vehicle 100 has a front door 10, a rear door 30, a front pillar (front column) 40, a center pillar (middle column) 50, and a rear pillar (on the side) as viewed from the passenger seated in the passenger compartment. A rear pillar 60) is provided. The front pillar 40 is erected on the front side of the window panel 18, the center pillar 50 is erected at a position sandwiched between the window panels 18 and 38, and the rear pillar 60 is erected on the rear side of the window panel 38. Further, a front seat 72 and a rear seat 74 having seating portions 73 and 75 whose upper surfaces are seated on the passengers 73a and 75a are provided in the vehicle interior.
The pillar garnish interior materials 42, 52, 62 are interior materials laid on the passenger compartment side of the pillars 40, 50, 60, and are laid to obtain a good design. Recently, a function of an impact absorbing material that absorbs an impact when the head of an occupant comes into contact is also expected. In this case, a lattice-like rib is formed on the back surface of the pillar garnish interior material, and the ribs are formed. Takes a structure that absorbs shock by buckling. The pillar garnish interior material is a member in which a thermoplastic resin is formed into a thin plate shape by injection molding or press molding, and since it is close to the head of an occupant, an audio speaker may be provided. There are cases where the surface of the interior base material is covered with a skin material and where it is not covered.

  The door trim interior materials 20 and 32 are laid inside the doors 10 and 30, and are engaged with the door inner panel 14 by resin clips or the like. The driver seat door trim interior material 20 includes an interior base material 22 having a self-shape retaining property and a designable skin material 24 attached to the surface of the interior base material 22 on the vehicle compartment side. Door trim interior materials other than the driver's seat door trim interior material have the same interior base material and skin material. As the interior base material, a wood base material formed by blending a wood fiber with a binder, a resin base material obtained by molding a thermoplastic resin plate into a predetermined shape, or the like can be used. On the vehicle interior side of the interior base material, an occupant's armrest part, a pocket shape of an accessory case, and the like are formed. Also, the center part of the door trim interior material and the upper side of the armrest part are called ornament parts, and a pad material of another design may be stuck on the skin material. The sound absorbing structure ST1 of the present invention can be applied to the ornament part, for example. The interior base material 22 is formed with a recess 23 by deeply molding the ornamental portion in anticipation of the thickness L1 of the sound absorbing material 26 from the general surface 22a.

FIG. 2 shows that a part of the general surface 22a of the interior base material is formed in a recess 23 that is lowered from the general surface 22a, and the sound absorbing material 26 is inserted and embedded in the recess 23 from the passenger compartment side. A sound absorbing structure ST1 is shown in which 22a and the sound absorbing material 26 are continuously covered with a skin material 24 having high air permeability (low air resistance).
The vehicle body panel of the present embodiment includes a metal door outer panel 12 and a metal door inner panel 14 disposed on the vehicle compartment side of the door outer panel. The distance L4 between the vehicle body panels 12 and 14 can be about 5 to 100 mm.

The interior base material 22 is made of polypropylene (PP), acrylonitrile butadiene styrene resin (ABS resin), or other thermoplastic resin (a type of synthetic resin), various thermosetting resins (a type of synthetic resin), or wood fiber. A member formed by binding with a binder such as a synthetic resin can be used. And an interior base material is formed by shape | molding the raw material for interior base materials in the predetermined | prescribed shape which has the recessed part 23 by shaping | molding, such as press molding and injection molding.
The thickness of the interior base material 22 can be 1 to 10 mm.

In the present embodiment, the sound absorbing material 26 is described as being bonded and fixed to the recess 23 with an adhesive. However, the sound absorbing material 26 may be configured to be bonded and fixed with a double-sided tape. It is good also as a structure which is formed in the shape which can be engaged and a sound-absorbing material is engaged with a recessed part, and is fixed.
The size of the concave portion 23 of the interior base material when projected from the vehicle compartment side to the vehicle outer side opposite to the vehicle compartment side (the size of the concave portion when looking out of the vehicle from the vehicle interior) is determined in the longitudinal direction of the automobile. The length L2 can be set to about 1300 mm and the length L3 in the height direction of the automobile can be set to about 400 mm. The length L2 can be determined in a range smaller than the interior base material according to the size of the interior base material. In addition to forming one large recess, a plurality of small recesses may be formed.
The depth L5 of the recess 23 of the interior base material can be about 3.5 to 110 mm, more preferably about 3.5 to 70 mm. It should be noted that the shallower the recess, the higher the frequency of the sound that is absorbed, and the deeper the recess, the easier the absorption of the low-frequency sound.
The space | interval of the interior base material 22 and the door inner panel 14 can be about 0 to 60 mm at a general part, and about 0 to 30 mm at a recessed part.

As the material of the skin material, woven fabric, non-woven fabric, knit, various leathers having a large number of minute ventilation holes, and the like can be used. The skin material 24 has a high air permeability of 6 cc / cm ² / sec or more in air permeability (according to the fragile method defined in JIS L1096, hereinafter the same). The skin material 24 is installed on the vehicle interior side of the interior base material 22 so as to close the opening 23 a of the recess 23. Intrusion sounds such as road noise and wind noise that have entered the vehicle compartment enter the sound absorbing material 26 through the highly breathable skin material 24, and energy is attenuated and absorbed.
When the air permeability of the skin material is 6 cc / cm ² / sec or more, the sound absorbing property by the sound absorbing material 26 does not decrease, so that the design of the passenger compartment can be improved while maintaining good sound absorbing property. It is presumed that the sound absorbing property is maintained because sound waves traveling from the passenger compartment to the sound absorbing material are hardly reflected, and sound energy is sufficiently absorbed by the sound absorbing material.

  The sound absorbing material 26 may be a material having a sound absorbing effect, and a porous sound absorbing material can be used. When a porous sound absorbing material is used, a good sound absorbing effect can be obtained. As the material of the sound absorbing material, a material in which synthetic fibers such as synthetic felt are aggregated, a material in which a synthetic resin such as a thermoplastic resin or a thermosetting resin is foamed, a combination thereof, or the like can be used. As the synthetic felt, PET fiber, PP fiber, half-hair fiber, a combination thereof, or the like can be used. As the material obtained by foaming the synthetic resin, a breathable resin foam, a bead molded body, a combination thereof, or the like can be used. Moreover, you may use the foamed synthetic resin shape | molded, making many foam the synthetic resin particles formed in the cylinder shape. Each cylindrical resin particle impregnated with a foam material has a cylindrical shape with an inner diameter d of about 2 to 4 mm, an outer diameter D (D> d) of about 4 to 6 mm, and a length L of about 3 to 6 mm. Can do. These parameters are parameters that affect the sound absorbing performance of the sound absorbing material. By setting the inner diameter d, the outer diameter D, and the length L within these ranges, very good sound absorbing performance is obtained for the sound absorbing material. Is granted. As such cylindrical resin particles, PEPP (porous EPP) manufactured by GS Corporation can be used. Needless to say, the cylindrical resin particles may have a shape in which the cross section is flattened to be substantially elliptical in addition to the cylindrical shape.

The thickness L1 of the sound absorbing material 26 in the direction connecting the passenger compartment side and the vehicle exterior side is preferably not more than the depth L5 of the recess 23 and not less than 3 mm. Therefore, the thickness L1 of the sound absorbing material can be about 3 to 110 mm, more preferably about 3 to 70 mm. This is because it is preferable that L1 is 3 mm or more in that sufficient sound absorbing performance can be obtained.
The size of the sound absorbing material 26 (length in the front-rear direction × length in the height direction) is adjusted to the size of the recess 23 of the interior base material (length L2 in the front-rear direction × length L3 in the height direction). Just decide.

The sound absorbing material 26 of the present embodiment is formed with at least one of a material in which synthetic resin is foamed and a material in which synthetic fibers are aggregated without forming a through hole that connects the passenger compartment side and the vehicle exterior side, and has a density. Is 0.02 to 0.25 g / cm ³ . This is because a density of 0.02 g / cm ³ or more is preferable in that good hardness can be obtained, and a density of 0.25 g / cm ³ or less is preferable in that a good sound absorbing effect can be obtained.
Further, the sound absorbing material 26 of the present embodiment made of the above material has a Shore hardness (hereinafter referred to as Shore C hardness) of 10 to 70 according to a spring type hardness tester C type. When the Shore C hardness is 10 or more, it is preferable in terms of obtaining a good hardness that does not become depressed even when pressed, and when it is 70 or less, it can be sufficiently lightened and a good sound absorbing effect can be obtained. It is because it is preferable. If the sound absorbing material has an appropriate degree of softness, it is presumed that the sound absorption is improved due to the cushion effect that makes it difficult for sound waves to be reflected.

The sound absorbing material 26 can be formed using various known techniques. For example, the raw material of the thermoplastic resin and the foaming agent are supplied to an injection molding machine with a heater, and the raw material is heated and melted with a heater while mixing the two, so that the sound absorbing material 26 is formed. The sound-absorbing material 26 can be formed by injecting and molding a foamed thermoplastic resin melted into a predetermined mold, and cooling the mold to solidify the resin. When the sound-absorbing material 26 is formed using a thermosetting resin, the resin is cured while foaming by injecting a liquid thermosetting resin and a foaming agent into a predetermined mold and heating the mold. Alternatively, it can be formed by adding a foaming agent and a curing agent to a liquid thermosetting resin and injecting it into the mold and then curing the resin while foaming it for a predetermined time. Of course, the sound absorbing material 26 can also be formed by press molding or the like.
In order to adjust the density and Shore C hardness of the sound absorbing material 26, for example, the blending ratio of the resin and the foaming agent may be adjusted to adjust the expansion ratio. If the blending ratio of the foaming agent is increased, the expansion ratio is increased, the density is decreased, and the Shore C hardness is decreased. Moreover, the density and the Shore C hardness of the sound absorbing material can also be adjusted by adjusting the foaming temperature.

  By the way, a road vehicle traveling at a high speed on the road generates a relatively large road noise and wind noise compared to a vehicle traveling outside the road traveling at a relatively low speed. As a result of experiments, it was found that road noise generated on the road surface entered the passenger compartment mainly along the route indicated by the solid and broken arrows in FIG. 3 and reached the passenger's ear. Here, the solid line arrow in the figure indicates that road noise enters the vehicle interior through the gap between the door 10, 10 'and the floor panel 79, and proceeds upward in the vicinity of the side surface of the vehicle interior of the door 10, 10'. It shows the route that the passenger enters the ear. Also, the broken line arrows in the figure indicate that road noise travels upward through the gap between the outer panels 12, 12 'and the inner panels 14, 14', and from the upper edge of the vehicle body panels 12, 12 ', 14, 14'. It shows the route to enter the passenger compartment and enter the passengers' ears. Since there are tires below the door panels 12, 12 ′, 14, 14 ′, it is assumed that road noise enters the vehicle interior through these routes. Further, since there is a drain hole at the lower edge of the door panel 12, 12 ', 14, 14', road noise is generated from the drain hole into the gap between the outer panel 12, 12 'and the inner panel 14, 14'. It is inferred that it will invade and propagate upward.

  Based on the above experimental results, the seating surfaces 73a of the seats 72, 72 ′ having the seating portions 73, 73 ′ whose upper surfaces are the seating surfaces 73a, 73a ′ of the occupants in the vehicle interior of the door trim interior materials 20, 20 ′. A recess is formed above 73a ′, and sound absorbing structures ST1, ST1 ′ formed by embedding a sound absorbing material in the recess are provided. Thereby, since the sound is absorbed above the seating surface in the door trim interior material, it is possible to more effectively reduce the intrusion sound entering the occupant's ear and further improve the quietness during traveling.

When the density is lower than 0.25 g / cm ³ , the sound absorbing characteristic of the sound absorbing material 26 is a characteristic that causes a peak at 400 to 4000 Hz. Explaining with reference to FIG. 7 that compares the normal incident sound absorption rate of the sound absorbing material (the ratio of the sound absorption sound intensity to the sound intensity before incident) with respect to the frequency band for each 1/3 octave band, the peak frequency f _p is greater than both normal incidence sound absorption coefficient vertically incident sound absorption rate in frequency f _p-1, f p _{+ 1} before and after the frequency f _p when the frequency is changed every 1/3-octave bands, one step A frequency at which the normal incident sound absorption coefficient at the small frequency f _p-1 is larger than the normal incident sound absorption coefficient at the smaller frequency f _p-2 by one step and the normal incident sound absorption coefficient at the one step larger frequency f _{p + 1} is one step larger. Let us say that it is greater than the normal incidence sound absorption coefficient at fp _{+ 2} . FIG. 7 shows a holeless sound absorbing material in which a peak is not generated at 400 to 4000 Hz, and a holed sound absorbing material in which a through hole connecting the vehicle compartment side and the vehicle exterior side is formed in the holeless sound absorbing material (second embodiment). The graph which compares the normal incidence sound absorption coefficient with respect to the frequency band (unit: Hz) for every 1/3 octave band is shown. In the graph, the normal incident sound absorption coefficient is plotted for each 1/3 octave band center frequency. The normal incident sound absorption coefficient was measured by a general method for measuring normal incident sound absorption coefficient.
If the density is higher than 0.25 g / cm ³ , the sound absorbing property of the sound absorbing material 26 is a property that does not cause a peak at 400 to 4000 Hz.
In addition, when a molded product of chip urethane was used as the sound absorbing material 26, a sound absorbing characteristic that produced a peak at 400 to 4000 Hz was obtained when the density was 0.25 g / cm ³ or less, and the density was 0.25 g. When the frequency is greater than / cm ^{3, a} sound absorption characteristic that does not cause a peak at 400 to 4000 Hz is obtained. Here, chip urethane is a recycled material obtained by finely cutting a waste material of urethane foam (foamed urethane) and hardening it with a binder.
From the above, in the sound absorbing material without holes, good sound absorbing properties can be obtained by setting the density to 0.25 g / cm ³ or less.

In addition, when using the molded body formed by assembling a large number of the above-described cylindrical resin particles into the sound absorbing material, the density is usually 0.25 g / cm ³ or less, and the sound absorbing characteristics of the sound absorbing material 26 peak at 400 to 4000 Hz. The resulting characteristics. In the sound absorbing material using the cylindrical resin particles, air permeability is imparted to the sound absorbing material by the holes formed in the cylindrical resin particles, and the passenger compartment side and the vehicle exterior side are connected through the holes of the cylindrical resin particles. It is assumed that the intrusion sound enters the hole of the cylindrical resin particle and is repeatedly reflected, and the energy of the intrusion sound is attenuated.

It can be considered that the sound absorption characteristics change at a density of 0.25 g / cm ³ because the hardness of the sound absorbing material changes.
FIG. 4 is a graph showing the relationship between density and Shore C hardness for a plurality of sound absorbing materials having different densities. The test method is the same as the test method of FIG. A chip urethane molded body was used for the sound absorbing material 26.
As shown in the figure, the Shore C hardness is approximately a relationship determined by a linear function of density, and increases as the density increases. When the Shore C hardness is less than about 70, the sound absorbing characteristic of the sound absorbing material 26 is a characteristic that causes a peak at 400 to 4000 Hz. On the other hand, when the Shore C hardness is greater than about 70, the sound absorbing characteristic of the sound absorbing material 26 is a characteristic that does not cause a peak at 400 to 4000 Hz.
From the above, by setting the Shore C hardness of the sound absorbing material to 70 or less, good sound absorbing properties can be obtained.

The sound absorbing structure ST1 may be formed as follows.
First, the interior base material 22 is molded into a predetermined shape having the recesses 23, and the molded interior base material 22 is attached to the inner panel 14. Further, the sound absorbing material 26 is formed in a predetermined shape. Next, the sound absorbing material 26 is embedded in the recess 23 and fixed to the recess 23. Even at this stage, it functions as the sound absorbing structure of the present invention. However, in this embodiment, the highly breathable skin material 24 is further attached to the general surface 22a of the interior base material and the side surface of the sound absorbing material 26 to the sound absorbing structure ST1. Form.

(2) Action and effect of sound absorption structure of road-traveling automobile:
Intrusion sounds such as road noise, wind noise, and engine noise that have entered the vehicle interior are reflected directly or by various fittings in the vehicle interior and transmitted through the highly breathable skin material 24 and enter the sound absorbing material 26. . Since the sound absorbing material 26 attenuates the energy of the intrusion sound that has entered, the intrusion sound that has entered the vehicle interior is reduced. When a porous sound absorbing material is used, the intruding sound enters the fine holes of the sound absorbing material and is diffusely reflected, and the energy of the intruding sound is attenuated.
Here, the sound absorbing material embedded in the recess formed above the seating surface with respect to the interior base material that is the side as seen from the occupant seated in the seating part attenuates the sound, so the load that has entered the vehicle interior Intrusion noise such as noise is absorbed at a position close to the passenger's ear on the side of the passenger and is efficiently reduced. This eliminates the need to install the sound absorbing material over the entire interior of the vehicle, thereby reducing the material cost of the sound absorbing material and eliminating the need for installing the sound absorbing material over the entire surface of the vehicle interior. The Further, since the sound absorbing material 26 is inserted into the recess 23 of the interior base material, a good design can be obtained and the safety is also good.
Therefore, for road vehicles, a simple configuration that only forms a sound absorbing structure by inserting a sound absorbing material into the recess of the interior base material, and at a low cost, a good design and good safety while obtaining the ear of the passenger. It is possible to effectively reduce intrusion sounds such as road noise and wind noise that enter the vehicle and improve quietness during running.
Further, since the air permeability of the skin material is sufficiently large, a good design in the vehicle compartment can be obtained without reducing the sound absorption effect.

  In addition, about the location which provides a sound absorption structure, it is good also as things other than the door trim interior material for driver's seats. For example, as shown in FIG. 3, the sound absorbing structure of the present invention may be provided in the passenger seat door trim interior material 20 ', or the sound absorbing structure of the present invention may be provided in the rear seat door trim interior material. Moreover, you may provide the sound absorption structure of this invention in the pillar garnish interior material 42,52,62. This is because the pillar is a body panel formed in a long cylindrical shape, and noise easily propagates inside the pillar while repeatedly reflecting inside the cylindrical pillar and easily enters the vehicle interior. Here, the sound absorbing structure of the present invention may be provided only in the pillar garnish interior material, or the sound absorbing structure of the present invention may be provided in both the pillar garnish interior material and the door trim interior material.

(3) Second embodiment:
FIG. 5 is a vertical sectional view showing the main part of the driver's seat door as viewed from a position corresponding to the position of A1-A1 in FIG. 1, and FIG. 6 is a view of the perforated sound absorbing material 126 from the same position as in FIG. FIG. In this embodiment, instead of the sound absorbing material 26 of the first embodiment, a perforated sound absorbing material 126 in which a through hole that linearly connects the passenger compartment side and the vehicle outer side is formed is used. The perforated sound absorbing material 126 in the figure shows an example in which a plurality of through holes 127 are formed. In the sound absorbing structure ST2 of the present embodiment, the perforated sound absorbing material 126 is embedded and fixed in the recess 23, and the general surface 22a of the interior base material and the perforated sound absorbing material 126 are continuously highly breathable (low airflow resistance). It is covered with a skin material 24.
The depth L15 of the recess 23 of the interior base material can be about 3.5 to 110 mm, more preferably about 3.5 to 70 mm. It should be noted that the shallower the recess, the higher the frequency of the sound that is absorbed, and the deeper the recess, the easier the absorption of the low-frequency sound.

As in the first embodiment, the material of the perforated sound absorbing material 126 is a material in which synthetic fibers such as synthetic felt are assembled, a material in which a synthetic resin such as a thermoplastic resin or a thermosetting resin is foamed, or a combination thereof. , Etc. can be used. Further, a foamed synthetic resin formed by aggregating and foaming a large number of synthetic resin particles formed in a cylindrical shape may be used, and parameters affecting the sound absorption performance may be the same as those in the first embodiment.
The thickness L11 of the perforated sound absorbing material 126 in the direction connecting the passenger compartment side and the vehicle exterior side is preferably not more than the depth L15 of the recess 23 and not less than 3 mm. Accordingly, the thickness L11 of the sound absorbing material can be about 3 to 110 mm, more preferably about 3 to 70 mm. This is because it is preferable that L11 is 3 mm or more in that sufficient sound absorbing performance can be obtained.
What is necessary is just to determine the magnitude | size of the perforated sound-absorbing material 126 according to the magnitude | size of the recessed part 23 of an interior base material.

The through hole 127 formed in the perforated sound absorbing material 126 is substantially circular.
The direction of the through-hole 127 formed in a straight line is a substantially horizontal direction connecting the passenger compartment side and the vehicle exterior side.
As shown in FIG. 6, generally, the through holes 127 formed in the perforated sound absorbing material 126 are distributed uniformly over the entire surface of the sound absorbing material 126 except for the peripheral edge to obtain good sound absorption. However, it may be arranged unevenly depending on the shape of the interior material. For example, it is conceivable to arrange many through holes on the side close to the position of the passenger's ear, or arrange many through holes on the side where sound waves enter. Further, it is considered that the rigidity of the sound absorbing material can be increased by arranging the through holes in a staggered manner as shown in FIG.
The diameter (diameter d1) of the through holes 127 formed in the sound absorbing material is preferably 1 to 10 mm, more preferably 1 to 5 mm. A diameter of 1 mm or more is preferable in that sound waves can enter easily and good sound absorption is obtained, and a diameter of 10 mm or less (more preferably 5 mm or less) gives unevenness when the occupant touches the skin material. This is because it is preferable. Note that the smaller the diameter d1 of the through hole, the higher the sound absorption characteristic peak shifts to the higher frequency side and the higher frequency sound can be absorbed, and the larger the larger the sound absorption characteristic peak shifts to the lower frequency side, the lower the frequency. The sound of can be absorbed. Therefore, by adjusting the diameter d1 of the through hole, the intrusion sound can be absorbed around the desired frequency.

When the total area S2 of the projected area of the through hole 127 with respect to the projected area S1 of the sound absorbing material 126 when projected from the passenger compartment side to the vehicle outer side is referred to as an opening ratio p = (S2 / S1) of the sound absorbing material. The opening ratio is preferably 2 to 30% as a percentage. If it is 2% or more, it is preferable in that the sound absorbing effect by the through hole 127 is sufficiently obtained, and if it is 30% or less, it is preferable in that the sound absorbing material is sufficiently maintained in shape and sufficient hardness is obtained. Note that if the diameter of each through hole 127 is d1 and the number of through holes 127 is n1, then p = n1 × π (d1 / 2) ² / S1. The projected area S1 of the present embodiment corresponds to the area of the sound absorbing material 126 depicted in FIG. 6, and the projected area S2 corresponds to the sum of the areas of the through holes 127 depicted in FIG.
The perforated sound absorbing material 126 can also be formed in the same manner as the sound absorbing material 26 of the first embodiment.

The perforated sound absorbing material 126 of this embodiment is formed of at least one of a material obtained by foaming synthetic resin and a material obtained by collecting synthetic fibers, and has a density of 0.25 to 0.40 g / cm ³ . When the density is 0.25 g / cm ³ or more, a sound absorption effect is obtained by forming a through hole that connects the inside and outside of the vehicle, and when the density is 0.40 g / cm ³ or less, the sound absorption effect by the through hole and the material of the sound absorbing material are obtained. This is because the sound absorption effect by itself is preferable in that a good sound absorption effect can be obtained. The density of the perforated sound absorbing material 126 is the density of the portion excluding the through hole 127, that is, the density of the material not forming the through hole.
Further, the perforated sound absorbing material 126 of the present embodiment made of the above material has a Shore C hardness of 70 to 90. If the Shore C hardness is 70 or more, a sound absorption effect is obtained by forming a through hole connecting the inside and the outside of the vehicle, and if it is 90 or less, the sound absorption effect by the through hole and the sound absorption effect by the material of the sound absorbing material itself are good. This is because a favorable sound absorbing effect can be obtained.

As described above, when the density is higher than 0.25 g / cm ³ , the sound absorbing characteristics of the sound absorbing material without holes are characteristics that do not cause a peak at 400 to 4000 Hz. When a perforated sound absorbing material is formed using the same material as this non-perforated sound absorbing material and a through hole connecting the passenger compartment side and the outside of the vehicle is formed, the sound absorbing characteristic of the perforated sound absorbing material is a characteristic that causes a peak at 400 to 4000 Hz. Even better characteristics are obtained. This is presumably because the intrusion sound enters the through hole and is repeatedly reflected, and the energy of the intrusion sound is attenuated.
In view of the above, the vehicle interior side and the vehicle exterior side are made of a material capable of absorbing sound that does not have a through hole that connects the vehicle interior side and the vehicle exterior side, and has a sound absorption characteristic that does not cause a peak at a frequency of 400 to 4000 Hz. A perforated sound absorbing material may be formed by forming a plurality of through-holes connecting each other with a diameter of 1 to 10 mm (more preferably 1 to 5 mm). By forming a through hole having a diameter of 1 to 10 mm (more preferably 1 to 5 mm), a sound absorption characteristic peak is generated at a frequency of 400 to 4000 Hz, so that a good sound absorption property can be obtained in a wider frequency range. Characteristics can be improved.

FIG. 7 shows an example of a holeless sound absorbing material that does not cause a peak at 400 to 4000 Hz and a perforated sound absorbing material in which a through hole that connects the vehicle compartment side and the vehicle exterior side is formed in the holeless sound absorbing material. The graph which compared the normal incidence sound absorption coefficient with respect to a frequency band is shown. For the sound absorbing material without holes, a molded body in which chip urethane was formed into the shape of the sound absorbing material without holes was used. As the perforated sound absorbing material 126, a material in which a large number of through holes having a diameter of 2.0 mm were formed in the arrangement shown in FIG.
As shown in the figure, even with a holeless sound absorbing material that does not cause a peak at 400 to 4000 Hz, by forming a through hole that connects the passenger compartment side and the vehicle exterior side, 400 to 4000 Hz (in the example shown, around 1000 Hz) ). That is, it is shown that even better sound absorbing properties can be obtained by using a perforated sound absorbing material in which a through hole connecting the passenger compartment side and the vehicle exterior side is formed with a diameter of 1 to 10 mm.

FIG. 8 shows a graph comparing the normal incident sound absorption coefficient with respect to the frequency band (unit: Hz) for each 1/3 octave band of two types of perforated sound absorbing materials with different densities. In the graph, the normal incident sound absorption coefficient is plotted for each 1/3 octave band center frequency. The test method is the same as the test method of FIG. The perforated sound-absorbing material 126 is PEPP made of foamed polypropylene as cylindrical resin particles (porous EPP, inner diameter 3 mm, outer diameter 5 mm, length 4 mm, density 0.045 g / cm ³ ). A molded body having a density of 0.03 g / cm ³ was used by assembling a large number of bead foams) into a shape of a perforated sound absorbing material 126 having a large number of through-holes having a diameter of 2.0 mm. As a comparative example, a molded body in which a large number of the same cylindrical resin particles were aggregated and foam-molded into a shape of a sound absorbing material without holes and the density was 0.03 g / cm ³ was used.

When a through hole connecting the passenger compartment side and the vehicle exterior side is not formed, as shown by the solid broken line in the figure, the sound absorption characteristic of the sound absorbing material formed by assembling a large number of cylindrical resin particles is about 1000 Hz and 4000 Hz. The sound absorption characteristic produces a peak around ˜5000 Hz. On the other hand, when a through hole connecting the passenger compartment side and the vehicle exterior side is formed with a diameter of 1 to 10 mm, the peak near the frequency of 1000 Hz shifts to around 2000 Hz as shown by the broken line in the figure, and the normal incident sound absorption coefficient. And a peak near a frequency of 4000 to 5000 Hz has a sound absorption characteristic in which the normal incident sound absorption coefficient is increased as it is.
From the above, even better sound absorbing properties can be obtained by using a perforated sound absorbing material in which a through hole connecting the passenger compartment side and the vehicle outer side is formed with a diameter of 1 to 10 mm.

Next, the operation and effect of the second embodiment will be described.
The intrusion sound into the vehicle interior is reflected directly or by various fittings in the vehicle interior, passes through the highly breathable skin material 24, and enters the perforated sound absorbing material 126. Since the perforated sound absorbing material 126 attenuates the energy of the intruding sound that has entered, the intruding sound into the vehicle compartment is reduced. Further, since the intrusion sound enters the through hole and is repeatedly reflected, the energy of the intrusion sound is attenuated, so that the intrusion sound into the vehicle interior is also reduced in this respect.
Here, since the perforated sound absorbing material embedded in the recess formed above the seating surface attenuates the sound, the intruding sound that has entered the passenger compartment is at a position close to the passenger's ear on the side of the passenger. Absorbed and efficiently reduced. Thereby, the material cost of the sound absorbing material is reduced, and the cost of the work of installing the sound absorbing material is also reduced. Furthermore, since the perforated sound absorbing material 126 is inserted into the recess 23 of the interior base material, a good design can be obtained and the safety is also good.
Therefore, for road vehicles, the occupant can obtain a good design and good safety at a low cost with a simple configuration that only forms a sound absorbing structure by inserting a perforated sound absorbing material into the recess of the interior base material. It is possible to effectively reduce the intrusion sound entering the ears of the vehicle and improve the quietness during running. Further, since the air permeability of the skin material is sufficiently large, a good design in the vehicle compartment can be obtained without reducing the sound absorption effect.

Note that the various modifications of the sound absorbing material, the various modifications of the through holes, and the modifications of the place where the sound absorbing structure is provided described in the first embodiment are also applicable to the second embodiment.
9 is a perspective view showing an example in which the sound absorbing structure ST3 of the present invention is provided in the pillar garnish interior material P1, and FIG. 10 is a horizontal sectional view showing the pillar garnish interior material P1 as viewed from the position A2-A2 in FIG. It is. In this modification, the recessed part P3 is formed in the vehicle interior side with respect to the interior base material P2 of the pillar garnish interior material. A perforated sound absorbing material P6 in which a large number of through holes P7 connecting the vehicle interior side and the vehicle exterior side are formed is inserted and embedded in the recess P3 from the vehicle interior side.

The material of the interior base material, the thickness, the depth of the recess, the material of the perforated sound absorbing material, the thickness of the perforated sound absorbing material, the arrangement of the through holes, the diameter of the through holes, and the opening ratio are the holes embedded in the recesses of the door trim interior material The same conditions as those for the empty sound absorbing material may be used. The size of the recess when looking outside the vehicle from inside the vehicle interior, and the size of the perforated sound absorbing material when looking outside the vehicle from the inside of the vehicle are in a range smaller than the interior material depending on the size of the interior material. You just have to decide. In this modification, the skin material is not pasted on the surface, but a skin material may be pasted to improve the design.
The recess P3 is formed above the seating surface (73a in FIG. 1) of the seat in the pillar garnish interior material P1.
Even with the above configuration, the intrusion sound into the vehicle compartment enters the perforated sound absorbing material P6 and the energy is attenuated. Further, the intrusion sound enters the through hole P7 connecting the passenger compartment side and the vehicle exterior side and repeats reflection, and the energy is effectively attenuated. Here, since the perforated sound absorbing material embedded in the recess formed above the seating surface attenuates the sound, the intruding sound is absorbed at a position close to the passenger's ear on the side of the passenger, which is efficient. Reduced to Furthermore, since the sound absorbing material P6 is inserted into the recess P3 of the interior base material, a good design is obtained and the safety is also good. Accordingly, it is possible to effectively reduce the intrusion sound that enters the passenger's ear while obtaining a good design and good safety at low cost.

The direction of the through hole of the perforated sound absorbing material can be various directions other than the substantially horizontal direction connecting the vehicle compartment side and the vehicle outer side as in the present embodiment.
For example, as shown in FIG. 11, the sound absorbing structure ST <b> 4 may be configured using a perforated sound absorbing material 226 in which the vehicle interior side is lower than the outside of the through hole of the perforated sound absorbing material. For intrusion sounds that enter the vehicle compartment from the bottom, such as road noise, it is considered that the use of the perforated sound absorbing material 226 in which the vehicle interior side of the through hole is lower than the outside of the vehicle facilitates entry into the through hole 227. It is thought that sound absorption can be improved.

  Further, as shown in FIG. 12, a hollow sound absorbing material 326 in which a through hole 327 is formed is inserted into the concave portion 23 from the passenger compartment side, and a hollow portion H1 for resonating the sound entering from the through hole 327 with the concave portion 23 is formed. You may comprise the sound absorption structure ST5 arrange | positioned so that it may form. The hollow portion H1 formed by the perforated sound absorbing material 326 and the concave portion 23 resonates the sound entering from the through hole 327 and attenuates it by the theory of the Helmholtz resonance tube. It becomes possible to reduce more effectively. Here, the smaller the thickness of the hollow portion H1 in the direction connecting the passenger compartment side and the vehicle exterior side, the higher the frequency of sound that can be absorbed, and the greater the size, the lower the frequency of sound that can be absorbed.

(4) Example:
EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited by an Example.

[Example 1]
As the interior base material, a 2.5 mm thick polypropylene resin door trim base material was used. This door trim base material was molded into a shape having a recess at the center of the front door trim to form an interior base material. The concave portion has an opening formed in a rectangular shape, the length L2 in the longitudinal direction of the automobile is 600 mm, the length L3 in the height direction of the automobile is 300 mm, and the average depth is 20 mm.
As the sound absorbing material, a holeless sound absorbing material formed by bonding recycled fibers with a binder to an average thickness of 20 mm was used without forming a through hole connecting the passenger compartment side and the vehicle exterior side. The density of the sound absorbing material without holes was 0.12 g / cm ³ . This holeless sound absorbing material was embedded and fixed in the recess of the interior base material.
As the skin material, a needle punched nonwoven fabric made of polyester fiber was used. This skin material had a basis weight of 400 g / m ² and an air permeability of 45 cc / cm ² / sec. Then, the general surface of the interior base material and the vehicle interior side surface of the sound absorbing material without holes were continuously covered with this skin material, and the test sample of Example 1 was formed.

[Example 2]
As the interior base material and the skin material, those having the same configuration as in Example 1 were used.
As the sound-absorbing material, chip urethane molded with an average thickness of 20 mm is uniformly formed in a zigzag pattern as shown in FIG. 6 so that the opening ratio p is 5% for the through hole having a diameter d1 = 2.0 mm. Formed. This perforated sound absorbing material was embedded and fixed in the recess of the interior base material. The density of the perforated sound absorbing material was 0.30 g / cm ³ . Then, the test sample of Example 2 was formed by continuously covering the general surface of the interior base material and the side surface of the casing of the perforated sound absorbing material with the above skin material.

[Comparative example]
As the interior base material, the same 2.5 mm-thick polypropylene resin door trim base material as in Examples 1 and 2 was used. However, this door trim base material was molded into a shape excluding the concave portion referred to in the present invention to form an interior base material. In addition, no sound absorbing material was used. The same skin material as in Examples 1 and 2 was used as the skin material. Then, the casing side surface of the interior base material was covered with this skin material, and a test sample of a comparative example was formed.

[Test method]
Test samples of Examples 1 and 2 and Comparative Example were sequentially laid on a 1500cc engine, front engine, front drive passenger car (sedan type passenger car), and the test vehicle was placed in an anechoic chamber and 60km using a chassis dynamo The road noise was generated by creating a smooth road running state of / h. Then, using an ordinary sound level meter specified in JIS C1502 as an indicating mechanism, and a 1/3 octave band analyzer equivalent in JIS C1513, an A characteristic sound pressure at a position corresponding to the position of the driver's ear is used. The level (noise level) was measured.

[Test results]
The results are shown in FIG. 13 and FIG. FIG. 13 is a graph showing the A characteristic sound pressure level SPL (unit: dBA) with respect to the frequency band (unit: Hz) for each ３ octave band for Example 1 and the comparative example, and FIG. 14 is compared with Example 1. About an example, A characteristic sound pressure level SPL (unit: dBA) with respect to a frequency band (unit: Hz) for each 1/3 octave band is shown by a graph. In each graph, the measured value of the sound pressure level is plotted for each 1/3 octave band center frequency.
As shown in FIG. 13, in Example 1, the 1/3 octave band center frequency is 1250 Hz or higher and the sound pressure level is smaller than that of the comparative example, and high soundproof performance can be obtained in a high frequency region of 1250 Hz or higher. Was confirmed. Therefore, it was confirmed that the intrusion sound was absorbed with a simple configuration in which the holeless sound absorbing material was inserted into the recess of the interior base material to form the hollow portion.
As shown in FIG. 14, in Example 2, the 1/3 octave band center frequency is 800 Hz or higher and the sound pressure level is lower than that in the comparative example, and high soundproof performance is obtained in a wider frequency band than in Example 1. It was confirmed that Therefore, it was confirmed that a combined effect was produced in the through hole connecting the sound absorbing material, the vehicle compartment side, and the vehicle exterior side, and the intrusion sound was absorbed over a wider frequency range.

(5) Modification:
The present invention can be modified in various ways.
In each of the above-described embodiments, a rib for absorbing an impact may be formed on the outer surface of the interior base material, and the impact may be absorbed by buckling of the rib when the impact occurs. As such a rib, a rib having a lattice shape, a box shape, or the like can be employed. Then, it is preferable because more impact energy is absorbed when it comes into contact with the interior material when an impact occurs.

In each of the embodiments described above, when a cylindrical space is formed between the outer panel and the inner panel, this space may be blocked by a shielding material to reduce transmission of sound waves. As this type of shielding material, as disclosed in Japanese Patent Application Laid-Open No. 2001-341492, it is composed of a foam having a heat foaming property and a base material that supports the foam on the periphery. A ridge is formed on the periphery, and a body panel sealing material in which the foam is supported so as to cover at least a part of the ridge can be used. The unfoamed material is held in a cylindrical space (cavity) before the coating process, and the unfoamed material is foamed by heating (140 ° C. to 210 ° C.) that the body inevitably receives in the electrodeposition and baking coating processes. When the volume is increased, the cylindrical space can be sealed as a shielding material. As a result, the cylindrical space is blocked by the shielding material, so that the transmission of sound waves can be reduced as much as possible in the cylindrical space, the intrusion sound from outside the vehicle is reduced, and the occupant's ear is reached. The sound to be played can be reduced. In addition, as a preferable foaming material, an olefin-based foam material manufactured by Sika Corporation, which is disclosed in the publication, and a trade name “SEICA Baffle” (grade number SB240) can be used.
As described above, according to the present invention, various aspects can effectively reduce the intrusion sound entering the passenger's ear while obtaining a good design and good safety at low cost for road vehicles. It is possible to provide a useful sound absorbing structure, such as improving the quietness of the sound.

The side view which shows the principal part of the interior of a road traveling vehicle. The vertical cross section which shows the principal part of the door for driver's seats seeing from the position of A1-A1 of FIG. The front view which shows typically the penetration | invasion path | route of the noise from the outside of a vehicle by partially seeing the principal part of a road traveling vehicle. The figure which shows the relationship between a density and Shore C hardness with a graph. The vertical sectional view which shows the principal part of the door for driver's seats in 2nd embodiment seeing from the position equivalent to A1-A1 of FIG. The side view which shows a perforated sound absorbing material from the same position as FIG. The figure which shows the graph which compared normal incidence sound absorption coefficient. The figure which shows the graph which compared normal incidence sound absorption coefficient. The perspective view which shows the pillar garnish interior material which provided the sound absorption structure of this invention. The horizontal sectional view which shows a pillar garnish interior material seeing from the position of A2-A2 of FIG. The vertical sectional view which shows the principal part of the door for driver's seats seen from the position corresponding to A1-A1 of FIG. The vertical sectional view which shows the principal part of the door for driver's seats seen from the position corresponding to A1-A1 of FIG. The figure which shows the graph which compared the A characteristic sound pressure level of the position corresponded to the position of a driver | operator's ear by Example 1 and a comparative example. The figure which shows the graph which compared the A characteristic sound pressure level of the position equivalent to the position of a driver | operator's ear by Example 2 and a comparative example.

Explanation of symbols

10, 30 ... Door 12 ... Door outer panel (a kind of body panel)
14 ... Door inner panel (a kind of body panel)
18, 38 ... Window panel 20, 32 ... Door trim interior material 22, P2 ... Interior base material 23, P3 ... Recess 23a ... Opening 24 ... Skin material 26 ... Sound absorbing material 40, 50, 60 ... Pillars 42, 52, 62, P1 ... Pillar garnish interior materials 72, 74 ... Seats 73, 75 ... Seating portions 73a, 75a ... Seating surfaces 100 ... Road vehicles 126, 226, 326, P6 ... Perforated sound absorbing materials 127, 227, 327, P7 ... Through holes H1 ... Hollow part ST1, ST2, ST3, ST4, ST5 ... Sound absorption structure

Claims (11)

  A sound-absorbing structure for a road-traveling automobile in which an interior base material is provided on the vehicle compartment side with respect to a vehicle body panel and a seat having a seating portion whose upper surface is a seating surface of an occupant is provided in the vehicle interior. A concave portion is formed on the vehicle interior side above the seating surface with respect to the interior base material that is a side surface when viewed from the occupant, and a sound absorbing material capable of absorbing sound is embedded in the concave portion. The sound absorption structure of a road vehicle.   The interior base material that is the side as viewed from the occupant seated on the seating portion is a member provided on at least one of the door trim interior material and the pillar garnish interior material, and is above the seating surface with respect to the interior base material. The sound absorbing structure for a road vehicle according to claim 1, wherein the recess is formed on the vehicle compartment side.   The sound absorbing structure for a road vehicle according to claim 1 or 2, wherein the sound absorbing material is a porous sound absorbing material.   The sound absorbing material is a perforated sound absorbing material in which a through hole connecting the vehicle compartment side and the vehicle exterior side opposite to the vehicle compartment side is formed. A sound absorbing structure for a road vehicle according to any one of the above.   The perforated sound-absorbing material is a sound-absorbing material that does not have a through hole that connects the vehicle compartment side and the vehicle exterior side, and has a sound absorption characteristic that does not cause a peak at a frequency of 400 to 4000 Hz. The sound absorbing structure for a road vehicle according to claim 4, wherein the sound absorbing material is formed with a plurality of through-holes connecting the vehicle and the outside of the vehicle with a diameter of 1 to 10 mm.   6. The sound absorbing material for a road vehicle according to claim 4 or 5, wherein the perforated sound absorbing material is formed of at least one of a material obtained by foaming synthetic resin and a material obtained by collecting synthetic fibers. Construction. The perforated sound-absorbing material has a density of 0.25 to 0.40 g / cm ³ and a sound-absorbing material in which a plurality of through-holes connecting the vehicle compartment side and the vehicle exterior side are formed with a diameter of 1 to 10 mm. The sound absorbing structure for a road vehicle according to claim 6.   A plurality of through holes are formed in the perforated sound absorbing material, and the thickness of the perforated sound absorbing material in the direction connecting the vehicle compartment side and the vehicle outer side is equal to or less than the depth of the concave portion and 3 mm or more, The road area according to claim 6 or 7, wherein a total area of the projected area of the through hole with respect to a projected area of the perforated sound absorbing material when projected from the vehicle compartment side to the vehicle exterior side is 2 to 30%. Sound absorption structure of a traveling vehicle. The sound absorbing material is at least one of a material in which a synthetic resin is foamed and a material in which synthetic fibers are aggregated without forming a through hole that connects the vehicle interior side and the vehicle exterior side opposite to the vehicle interior side. The sound absorbing structure for a road vehicle according to claim 2 or ³ , wherein the density is 0.02 to 0.25 g / cm ³ .   The sound absorbing material is at least one of a material in which a synthetic resin is foamed and a material in which synthetic fibers are aggregated without forming a through hole that connects the vehicle interior side and the vehicle exterior side opposite to the vehicle interior side. 4. The sound absorbing structure for a road vehicle according to claim 2, wherein the Shore hardness is 10 to 70 according to the spring type hardness tester C type. A skin material that closes the opening of the recess is installed on the vehicle interior side of the interior base material, and the skin material has an air permeability of 6 cc / cm ² / sec or more according to JIS L1096. The sound-absorbing structure for a road vehicle according to any one of claims 1 to 10.

Images