JP2006142885A - Sound absorbing structure for automobile traveling on road - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively decrease noise heard by an occupant while obtaining good design and good safety, and to improve quietness at the time of traveling, in an automobile traveling on a road. <P>SOLUTION: A recessed portion 23 is formed on a vehicular cabin side in regard to an interior base material 22, and a platy member (a resonance member) formed with a through-hole 27 is inserted in the recessed portion 23 from the vehicular cabin side. A sound absorbing structure is provided, which is disposed so as to form a hollow portion H1 making sound entering from the through hotel 27 resonate with the recessed portion 23. A sound absorbing material may be disposed on a vehicular cabin side in the platy member. A large number of through holes is formed on the platy member, and the diameter of each hole is made to be 1 to 5 mm. The total area of a projecting area of the through hole to a projecting area of the platy member when projecting from the vehicular cabin side to the outside of a vehicle may be made to be 2 to 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 vehicle is provided with a hard layer having a microporous structure 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, although sound is absorbed to some extent by the hard layer having a microporous, it is presumed that the transmitted sound is larger than the sound absorption and the intrusion sound entering the passenger's ear is not effectively reduced.

  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 this document, a resonance chamber that requires a space portion independent of the cabin is provided on the ceiling wall in the cabin of the work vehicle, and pipes are further communicated from the resonance chamber into the cabin. It is described that the resonance frequency component of the diffused engine noise is attenuated and reduced by the frictional resistance with the surroundings 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 reduces intrusion sounds such as road noise and wind noise that enter the occupant's ear while obtaining good design and good safety for road vehicles, The purpose is to improve the quietness during running.

In order to achieve the above object, the present invention provides a sound absorbing structure for a road-traveling automobile in which an interior base material is provided on the vehicle interior side with respect to a vehicle body panel, and a recess is provided on the vehicle interior side with respect to the interior base material. The resonance member formed with the through hole is formed so as to be inserted into the concave portion from the vehicle compartment side so as to form a hollow portion that resonates the sound entering from the through hole with the concave portion. It is characterized by.
A resonance member having a through hole is inserted into a concave portion of the interior base material from the passenger compartment side, and a hollow portion is formed with the concave portion, and the theory of the Helmholtz resonance tube is formed by resonating the sound that has entered the through hole. Therefore, intrusion noise such as road noise that has entered the vehicle interior is reduced. Moreover, since the resonance member is inserted into the recess of the interior base material, a good design can be obtained and the safety is also good. Accordingly, 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.

  When a sound absorbing material is arranged on the vehicle interior side of the resonance member, good sound absorbing properties can be obtained in a wide frequency range. The frequency characteristic absorbed by the hollow portion and the frequency characteristic absorbed by the sound absorbing material are different because the principle of sound absorption is different. Thereby, sound absorption improves in a wider frequency range than in the case where sound is absorbed only by the hollow portion.

  The sound-absorbing material is at least one of a porous sound-absorbing material and a perforated sound-absorbing material in which a through hole that connects the vehicle compartment side and the vehicle exterior side opposite to the vehicle compartment side is formed. It is good also as a structure. If a porous sound absorbing material is used, the intruding sound enters the fine pores of the sound absorbing material and diffusely reflects, and the energy of the intruding sound is attenuated, so that a good sound absorbing property can be obtained. When the perforated sound absorbing material is used, the intruding sound enters the through hole and is repeatedly reflected, and the energy of the intruding sound is attenuated, so that a good sound absorbing property can be obtained.

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 hollow portion and the sound absorbing material does not deteriorate.

  The interior base material is a member provided on at least one of a door trim interior material and a pillar garnish interior material, the recess is formed on the vehicle interior side with respect to the interior base material, and the resonance member is the It is good also as a structure arrange | positioned so that it may be inserted in the said recessed part from the vehicle interior side and the said recessed part may form the said hollow part. 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.

  The recess is formed above the seating surface of a seat having a seating portion whose upper surface is a seating surface of an occupant in the vehicle interior in at least one of the door trim interior material and the pillar garnish interior material, and the resonance in the recess It is good also as a structure arrange | positioned so that a member may be inserted and the said recessed part may form the said hollow part. In the door trim interior material and the pillar garnish interior material, the sound is absorbed above the seating surface, so that the sound absorption can be improved more effectively and the quietness at the time of traveling can be improved.

  The resonance member may be a synthetic resin plate-like member in which the through hole is formed. Then, good sound absorption is obtained.

  A large number of through holes are formed in the resonance member, and if the diameter of each through hole is 1 to 5 mm, good sound absorption is obtained, and good rigidity is obtained for the resonance member.

  When the total area of the projected area of the through hole with respect to the projected area of the resonance member when projected from the passenger compartment side to the vehicle exterior is 2 to 30%, better sound absorption is obtained, and the resonance member Even better rigidity is obtained.

  When the thickness of the hollow portion in the direction connecting the passenger compartment side and the vehicle exterior side is 3 to 100 mm, good sound absorption is obtained.

According to the first aspect of the present invention, for road vehicles, it is possible to effectively reduce intrusion sounds such as road noise and wind noise that enter the ears of passengers while obtaining good design and good safety. Silence can be improved.
In the invention according to the second aspect, it is possible to obtain good sound absorption in a wide frequency range.
In the invention according to claim 3, it is possible to improve the sound absorption.

In the invention concerning Claim 4, it becomes possible to improve the designability in a vehicle interior, without reducing the sound absorption effect.
In the invention according to claim 5, it is possible to improve the sound absorption effect and further improve the quietness during traveling.
In the invention according to claim 6, it is possible to more effectively reduce the intrusion sound entering the passenger's ear and further improve the quietness during traveling.

In the invention concerning Claim 7, the resonance member from which a favorable sound-absorbing effect is acquired can be provided.
In the invention according to the eighth aspect, it is possible to obtain a good sound absorbing effect with a resonance member having a good rigidity.
In the invention according to the ninth aspect, it is possible to obtain a better sound absorption effect with a resonance member having a better rigidity.
In the invention according to the tenth aspect, it is possible to obtain an even better sound absorbing 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 sectional view seen from the position A1-A1, and FIG. 3 is a side view showing the plate-like member (resonance member) 26 seen from the same position as FIG. FIG. 4 is a front view schematically showing a noise intrusion route from the outside of the vehicle by partially viewing a main part of the road-traveling automobile 100. FIG. 5 is a graph for explaining the sound absorption characteristics of the sound that enters the passenger's ear by the sound absorption structure ST1.
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. In the sound absorbing structure ST1 of the present vehicle, the plate-like member 26 in which the through hole 27 is formed is inserted into the concave portion 23 from the passenger compartment side so as to form a hollow portion H1 that resonates the sound that has entered from the through hole with the concave portion. It is arranged and configured. This hollow portion is a closed space except for the portion of the through hole 27.

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. A recess 23 is formed in the interior base material 22 by deeply forming the ornamental portion in consideration of the thickness of the plate-like member 26 and the hollow portion H1 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 a flat plate-like member 26 is inserted into the recess 23 from the passenger compartment side and is hollowed by the recess. The sound absorbing structure ST1 is arranged so that the portion H1 is formed and the general surface 22a and the plate-like member 26 of the interior base material are continuously covered with the 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.

The opening 23a of the recess is provided with a stepped portion 23b having a shape matching the outer periphery of the plate-like member 26 when the outside of the vehicle is viewed from inside the vehicle interior. It is formed slightly smaller than the outer periphery. As a result, the plate-like member 26 is accommodated in the step portion 23b so as not to enter the outside of the vehicle with respect to the step portion. In the present embodiment, the plate-like member 26 is described as being bonded and fixed to the stepped portion 23b with an adhesive. However, the plate-like member 26 may be configured to be bonded and fixed with a double-sided tape. It is good also as a structure which forms in the shape which can be engaged with the outer peripheral part of this, and engages and fixes a plate-shaped member to a level | step-difference part. Of course, the plate-like member may be fixed to the recess without providing the stepped portion.
The size of the recess 23 of the interior base material when projected from the vehicle compartment side to the vehicle exterior (the size of the recess when looking outside the vehicle from the vehicle interior) is about 1300 mm in the longitudinal direction L2 of the vehicle. The length L3 in the height direction can be set to about 400 mm, and may 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 sound that can be absorbed, and the deeper the recess, the lower the frequency of sound that can be absorbed.
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. Since the plate-like member 26 is formed with a through hole 27 that communicates from the skin material 24 to the hollow portion H1, intrusion sounds such as road noise and wind noise that have entered the vehicle interior are highly breathable skin material 24. And enters the hollow portion H1 through the plate member 26. Here, the recess 23 and the plate-like member 26 constitute a Helmholtz resonance tube, and the resonance frequency component is attenuated and absorbed.
When the air permeability of the skin material is 6 cc / cm ² / sec or more, the sound absorption by the hollow portion H1 is not lowered, so that the design of the vehicle compartment can be improved while maintaining good sound absorption. It is presumed that the sound absorbing property is maintained because sound waves traveling from the passenger compartment to the hollow part are hardly reflected, and sound energy is sufficiently absorbed in the hollow part.

The material of the plate-like member 26 is a thermoplastic resin (a kind of synthetic resin) such as polypropylene (PP), acrylonitrile butadiene styrene resin (ABS resin), various thermosetting resins (a kind of synthetic resin), metal, etc. Can be used. Here, when the plate-like member having the through hole is a synthetic resin member, good sound absorption is obtained.
The thickness of the plate member 26 is preferably 0.5 to 10 mm. This is because 0.5 mm or more is preferable in that sufficient rigidity can be obtained, and 10 mm or less is preferable in that the weight is sufficiently light.
What is necessary is just to determine the magnitude | size of the plate-shaped member 26 according to the magnitude | size of the recessed part 23 of an interior base material.
The through hole 27 formed in the plate member 26 is substantially circular.
As shown in FIG. 3, generally, the through-holes 27 formed in the plate-like member 26 are distributed uniformly over the entire surface of the plate-like member 26 except for the peripheral edge. 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 plate-like member can be increased by arranging the through holes in a staggered manner as shown in FIG.
As a diameter (diameter d1) of many through holes 27 formed in the plate-like member, 1 to 5 mm is preferable. This is because a diameter of 1 mm or more is preferable in that sound wave permeability is improved and good sound absorption is obtained, and a diameter of 5 mm or less is preferable in that sufficient rigidity is obtained for the plate-like member.

When the total area S2 of the projection area of the through hole 27 with respect to the projection area S1 of the plate-like member 26 when projected from the passenger compartment side to the vehicle exterior side is referred to as an aperture ratio p = (S2 / S1) of the plate-like member. As an aperture ratio of a plate-shaped member, 2 to 30% is preferable in percentage. This is because if it is 2% or more, it is preferable in that a good sound absorbing effect is obtained, and if it is 30% or less, it is preferable in that sufficient rigidity can be obtained for the plate-like member. Note that if the diameter of each through hole 27 is d1 and the number of through holes 27 is n1, then p = n1 × π (d1 / 2) ² / S1. The projected area S1 of this embodiment corresponds to the area of the plate-like member 26 depicted in FIG. 3, and the projected area S2 corresponds to the sum of the areas of the through holes 27 depicted in FIG.
The plate-like member 26 can be formed using various known techniques. For example, a granular raw material of a thermoplastic resin such as polypropylene is supplied to an injection molding machine with a heater, and the raw material is heated and melted by a heater to form a plate-like member 26 in a predetermined mold. A plate-like member 26 can be formed by injecting and molding a molten thermoplastic resin to cool the mold and solidifying the resin. When the plate member 26 is formed using a thermosetting resin, by injecting a liquid thermosetting resin into a predetermined mold and then heating the mold to cure the resin, or It can be formed by adding a curing agent to a liquid thermosetting resin and injecting it into the mold and then curing the resin after a predetermined time. Of course, the plate-like member 26 can also be formed by press molding or the like.

  The thickness L1 of the hollow portion in the direction connecting the passenger compartment side and the vehicle exterior side can be about 3 to 100 mm, more preferably about 3 to 60 mm. This is because the thickness is preferably about 3 mm or more from the viewpoint of obtaining good sound absorption, and about 100 mm or less (more preferably about 60 mm or less) is preferable from the viewpoint that the space of the hollow portion can be easily secured.

  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. 4 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 in the gap between the outer panel 12, 12 'and the inner panel 14, 14' from the drain hole. 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 sound absorbing structure ST1, ST1 ′ is provided in which a concave portion is formed above 73a ′ and a hollow portion is formed by a plate-like member in which a through hole is formed. 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.

で求められる。従って、パラメータｐ，ｔ，φ，Ｌｔを調整することにより、所望の周波数を中心として車室内への侵入音を吸音することが可能であり、車室内の静粛性を向上させることができる。 The sound absorbing characteristics of the above-described sound absorbing structure ST1 are shown in the graph of FIG. Here, the horizontal axis of the graph indicates the frequency f (Hz), the vertical axis indicates the decrease ΔSPL (dBA) of the A characteristic sound pressure level (noise level) SPL, and the horizontal axis indicates the logarithmic axis. A curve S1 indicates ΔSPL corresponding to the frequency of the sound absorbing structure ST1. As shown by the curve C1, the sound absorption characteristic when sound is absorbed in the hollow portion H1 is a distribution characteristic centered on the center frequency (resonance frequency fc) for sound absorption. Therefore, the intrusion sound into the vehicle interior is absorbed around the frequency fc.
Here, the resonance frequency fc (Hz), which is the center frequency for sound absorption, is p for the aperture ratio of the plate member, t (m) for the thickness of the plate member, φ (m) for the diameter of the through hole, Assuming that the thickness is Lt (m) and the sound velocity is c (m / sec),

Is required. Therefore, by adjusting the parameters p, t, φ, and Lt, it is possible to absorb the intrusion sound into the vehicle interior around the desired frequency, and the quietness in the vehicle interior can be improved.

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 plate-like member 26 is formed in a predetermined shape having the through hole 27. Next, the plate-like member 26 is fitted into the step portion 23b of the concave portion and fixed to the opening portion 23a of the concave portion. Thereby, the hollow part H1 which resonates the sound which approached from the through hole 27 is formed. 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 of the passenger compartment of the plate-like member 26, thereby absorbing the sound. ST1 is formed.

(2) Action and effect of sound absorption structure of road-traveling automobile:
Intrusion sounds such as road noise, wind noise, engine noise and the like 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 hollow through the through hole 27. Enter the part H1. The hollow portion H1 attenuates the energy of the intruding sound by resonating the intruding sound that has entered from the through hole 27 according to the Helmholtz resonance tube theory, so that the intruding sound that has entered the vehicle interior is reduced. Further, since the plate-like member 26 is inserted into the recess 23 of the interior base material, a good design is obtained and the safety is also good. Therefore, for road vehicles, with a simple configuration that only inserts a resonance member into the recess of the interior base material to form a hollow portion, road noise that enters the passenger's ear while obtaining good design and good safety It is possible to effectively reduce intrusion sounds such as wind noise and improve quietness during traveling. 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.

  Furthermore, since the sound absorbing structure is formed above the seating surface in the door trim interior material, the sound is absorbed at a position closer to the passenger's ear, and the sound absorbing property is more effectively improved and the quietness during driving is improved. It becomes possible.

In addition to the flat plate shape, the resonance member in which the through hole is formed may be a plate member having a curved cross section such as a corrugated plate, a member having a curved surface, or the like. The shape of the through hole formed in the resonance member can be an arc shape, a polygonal shape, or the like other than the substantially circular shape. Further, only one through hole may be formed in the resonance member.
The place where the sound absorbing structure is provided may be other than the door trim interior material for the driver's seat. For example, as shown in FIG. 4, 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.
6 is a perspective view showing an example in which the sound absorbing structure ST2 of the present invention is provided on the pillar garnish interior material P1, and FIG. 7 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, a recess P3 having a stepped portion P3b is formed on the vehicle interior side with respect to the interior base material P2 of the pillar garnish interior material. A flat plate-like member (resonance member) P6 in which a large number of through holes P7 are formed is inserted into the concave portion from the passenger compartment side and fitted into the stepped portion P3b, and the sound entering the through hole P7 with the concave portion is heard. It arrange | positions in the opening part P3a of a recessed part so that the hollow part H2 to resonate may be formed.

The material of the interior base material, the thickness, the depth of the recess, the material of the plate member, the thickness of the plate member, the arrangement of the through holes, the diameter of the through holes, the aperture ratio, and the thickness of the hollow portion (corresponding to L1 in FIG. 2) These may be the same conditions as in the first embodiment. The size of the recess when looking outside the vehicle interior and the size of the plate-like member when looking outside the vehicle interior are within a range smaller than the interior base material depending on the size of the interior base material. Just 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 hollow portion H2 through the through hole P7 and resonates according to the theory of the Helmholtz resonance tube to attenuate the energy. Moreover, since the plate-like member 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 entering the passenger's ear while obtaining a good design and good safety.

(3) Second embodiment:
FIG. 8 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. The door trim interior material 120 of this embodiment also has a recess 123 formed on the interior side of the interior base material 122 that is lowered from the general surface 122a of the interior base material, and the opening 123a is viewed from outside the vehicle interior. A step portion 123b having a shape matching the outer periphery of the plate-like member 126 is provided. A plate-like member (resonance member) 126 having a large number of through holes 127 is also inserted into the recess 123 from the passenger compartment side and fitted into the stepped portion 123b, and is arranged so that a hollow portion H3 is formed with the recess 123. ing. In the sound absorbing structure ST3 of the present embodiment, the sound absorbing material 128 is further arranged on the vehicle compartment side of the plate-like member 126, and the general surface 122a of the interior base material and the sound absorbing material 128 are continuously made highly air permeable (low air resistance). ) Skin material 124.

The material and thickness of the interior base material 122, the size L2 × L3 of the recess 123, the material of the skin material 124, the air permeability, the material and size of the plate-like member 126, the arrangement of the through holes 127, the diameter d1 of the through holes, and the openings The rate p and the distance L4 between the interior base material 122 and the door inner panel 14 may be the same conditions as in the first embodiment.
For the same reason as in the first embodiment, the thickness L11 of the hollow portion H3 in the direction connecting the passenger compartment side and the vehicle exterior side can also be about 3 to 100 mm, more preferably about 3 to 60 mm.
The depth L15 of the concave portion of the interior base material can be a length obtained by adding the thickness of the plate-like member 126 and the thickness of the sound absorbing material 128 in the direction connecting the passenger compartment side and the vehicle exterior side to the thickness L11 of the hollow portion. It should be noted that the shallower the recess, the higher the frequency of sound that can be absorbed, and the deeper the recess, the lower the frequency of sound that can be absorbed.

The sound absorbing material 128 may be any material having a sound absorbing effect, and a porous sound absorbing material can be used. As the material of the sound absorbing material, synthetic felts such as PET fibers, PP fibers, and half-hair fibers, breathable resin foams, and 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 size of the sound absorbing material 128 may be determined according to the size of the recess 123 of the interior base material.
Also in the second embodiment, the door trim interior material 120 is provided with the sound absorbing structure ST3 in which the recessed portion 123 is formed above the seating surface of the seat, the hollow portion H3 is formed, and the sound absorbing material 128 is disposed in the opening 123a of the recessed portion. ing. As a result, the intrusion sound entering the passenger's ear can be reduced more effectively, and the quietness during running can be further improved.

  The sound absorption characteristic of the hollow portion H3 is a distribution characteristic centered on the resonance frequency fc obtained by the above-described equation (1). The frequency characteristic absorbed by the hollow portion H3 and the frequency characteristic absorbed by the sound absorbing material 128 are different because the principle of sound absorption is different. When the parameters p, t, φ, and Lt in (1) are determined and the concave portion 123 and the plate-like member 126 are formed with the determined parameters, the noise such as road noise is mainly in the sound absorption frequency range by the sound absorbing material 128. The sound is absorbed, and the resonance frequency component is mainly absorbed in the hollow portion H3. In FIG. 5, a decrease amount ΔSPL of the A characteristic sound pressure level corresponding to the frequency when felt is used as the sound absorbing material is shown in a curve C2, and the frequency when the felt and the hollow portion H3 are used together is shown. A corresponding decrease amount ΔSPL of the A characteristic sound pressure level is shown in a curve C3. In the example shown in the figure, a relatively high frequency component of the intrusion sound is absorbed by the felt, and a relatively low frequency component is absorbed by the hollow portion H3. It is shown that sound is absorbed in the range.

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 124, and passes through the sound absorbing material 128. Then, the energy of the intrusion sound attenuates due to the sound absorption characteristics of the sound absorbing material 128 as shown in FIG. When a porous sound absorbing material is used, the intruding sound enters the fine holes of the sound absorbing material and diffusely reflects, and the energy of the intruding sound is attenuated, so that a good sound absorbing property can be obtained. Then, the intruding sound transmitted through the sound absorbing material 128 enters the hollow portion H3 from the through hole 127, resonates according to the theory of the Helmholtz resonance tube, and the energy is attenuated around the resonance frequency fc. Thereby, sound-absorbing property is improved in a wider frequency range than when sound is absorbed only by the hollow portion. Moreover, since the plate-like member 126 and the sound absorbing material 128 are inserted into the recess 123 of the interior base material, a good design can be obtained and the safety is also good. Therefore, it is possible to effectively reduce the intrusion sound that enters the passenger's ear while obtaining a good design and good safety, and to improve the quietness of the traveling vehicle. 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.

  The various modifications of the resonance member, the various modifications of the through hole, and the modification of the place where the sound absorbing structure is provided described in the first embodiment can be applied to the second embodiment. When the sound absorbing structure is provided in the pillar garnish interior material, as described with reference to FIG. 7, the plate-like member P6 is inserted a little deeper into the recess P3, and the sound-absorbing material is disposed on the vehicle interior side of the plate-like member P6. .

  Further, as in the sound absorbing structure ST4 shown in FIG. 9, a perforated sound absorbing material 138 in which a through hole 139 connecting the vehicle compartment side and the vehicle exterior side opposite to the vehicle compartment side is formed as a sound absorbing material. Also good. The perforated sound absorbing material 138 in the figure shows an example in which a plurality of through holes 139 are formed. When the intrusion sound into the vehicle interior passes through the highly breathable skin material 124 and the perforated sound absorbing material 138, the intrusion sound enters the through hole 139 and is repeatedly reflected, and the energy of the intrusion sound is attenuated. Good sound absorption is obtained. Therefore, it is possible to effectively reduce the intrusion sound entering the passenger's ear while obtaining a good design and good safety, and to improve the quietness during running.

(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 22.5 mm.
A 2.5 mm thick polypropylene resin plate was used as the resonance member. A large number of through holes having a diameter d1 = 2.5 mm were uniformly formed in a zigzag pattern as shown in FIG. 3 so that the opening ratio p was 16%. The resonance member was attached to and fixed to the opening of the recess with the side surface of the interior of the resonance member aligned with the position of the general surface of the interior base material. The average thickness L1 of the hollow portion formed by the resonance member and the concave portion was 20 mm.
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. And the general surface of the interior base material and the cabin side surface of the resonance member were continuously covered with this skin material, and the test sample of Example 1 was formed.

[Example 2]
As the interior base material, the resonance member, and the skin material, the same configurations as those in Example 1 were used. However, the resonance member was inserted into the recess and fixed so that the average thickness L11 of the hollow portion formed by the resonance member and the recess was 10 mm.
As the sound absorbing material, polyester fiber cotton having a density of 0.15 g / cm ² was used. This polyester fiber cotton was laminated on the side surface of the passenger compartment of the resonance member so as to have a thickness of 10 mm. And the general surface of the interior base material and the cabin side surface of the resonance member were continuously covered with this skin material, and the test sample of Example 2 was formed.

[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. Moreover, the resonance member was not 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. 10 and FIG. FIG. 10 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. FIG. 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. 10, 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 is obtained in a high frequency region of 1250 Hz or higher. Was confirmed. Therefore, it is confirmed that a component in a specific frequency range centering on the resonance frequency fc is absorbed with respect to the intrusion sound with a simple configuration in which the resonance member is inserted into the recess of the interior base material to form a hollow portion. It was.
As shown in FIG. 11, in Example 2, the 1/3 octave band center frequency is 800 Hz or higher and the sound pressure level is smaller 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 composite effect was produced between the hollow portion and the sound absorbing material, 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 embodiment described above, the resonance member itself may be a sound absorbing material. Since the frequency characteristic absorbed by the hollow portion and the frequency characteristic absorbed by the resonance member itself are different because of the principle of sound absorption, it can be expected to improve sound absorption in a wider frequency range.

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 for a road vehicle, and quietness during driving Thus, it is possible to provide a useful sound absorbing structure.

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. FIG. 3 is a side view showing the resonance member as seen from the same position as in FIG. 1. 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 graph explaining the sound absorption characteristic of this sound absorption structure. 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 in 2nd embodiment seeing from the position equivalent 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, 120 ... Door trim interior material 22, 122, P2 ... Interior base material 23, 123, P3 ... Recess 23a, 123a ... Opening 24, 124 ... Skin material 26, 126, P6 ... Plate Member (resonance member)
27, 127, P7 ... through holes 40, 50, 60 ... pillars 42, 52, 62, P1 ... pillar garnish interior materials 72, 74 ... seats 73, 75 ... seating portions 73a, 75a ... seating surface 100 ... road-running automobile 128 ... Sound absorbing material 138 ... Perforated sound absorbing material 139 ... Through holes H1, H2, H3 ... Hollow portions ST1, ST2, ST3, ST4 ... Sound absorbing structure

Claims (10)

  A sound absorbing structure for a road-traveling automobile in which an interior base material is provided on the vehicle interior side with respect to the vehicle body panel, and a recess is formed on the vehicle interior side with respect to the interior base material and a resonance is formed through a through hole. A sound absorbing structure for a road vehicle, wherein the member is disposed so as to form a hollow portion that is inserted into the concave portion from the vehicle compartment side and resonates with the concave portion and the sound that has entered from the through hole.   The sound absorbing structure for a road vehicle according to claim 1, wherein a sound absorbing material is disposed on the vehicle interior side of the resonance member.   The sound-absorbing material is at least one of a porous sound-absorbing material and a perforated sound-absorbing material in which a through hole that connects the vehicle compartment side and the vehicle exterior side opposite to the vehicle compartment side is formed. The sound absorbing structure for a road vehicle according to claim 1 or 2. 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 3.   The interior base material is a member provided on at least one of a door trim interior material and a pillar garnish interior material, the recess is formed on the vehicle interior side with respect to the interior base material, and the resonance member is the The sound absorbing structure for a road vehicle according to any one of claims 1 to 4, wherein the sound absorbing structure is disposed so as to be inserted into the concave portion from the passenger compartment side to form the hollow portion with the concave portion. .   The recess is formed above the seating surface of a seat having a seating portion whose upper surface is a seating surface of an occupant in the vehicle interior in at least one of the door trim interior material and the pillar garnish interior material, and the resonance in the recess 6. The sound absorbing structure for a road vehicle according to claim 5, wherein a member is inserted so as to form the hollow portion with the concave portion.   The sound absorbing structure for a road vehicle according to any one of claims 1 to 6, wherein the resonance member is a plate-like member made of a synthetic resin in which the through hole is formed.   The sound absorbing structure for a road vehicle according to any one of claims 1 to 7, wherein the resonance member has a plurality of through holes, and each through hole has a diameter of 1 to 5 mm.   The sound absorbing structure for a road vehicle according to claim 8, wherein a total area of the projected area of the through hole with respect to a projected area of the resonance member when projected from the passenger compartment side to the vehicle outer side is 2 to 30%. The sound absorbing structure for a road vehicle according to any one of claims 1 to 9, wherein a thickness of the hollow portion in a direction connecting the passenger compartment side and the vehicle outer side is 3 to 100 mm.

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