Vehicle sound absorption structure

Abstract

A vehicle sound absorption structure has: a recessed cell that has an opening on one end of the cell; a divider that is provided within the cell and that divides an acoustic wave entering the cell from the opening into two acoustic waves; reflectors that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave; and an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been respectively reflected at the reflectors, to interfere with each other.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle sound absorption structure.

2. Description of Related Art

Japanese Utility Model No. 3048125 (JP-U-3048125) discloses an acoustic insulation material that is intended to prevent noise, such as engine sound generated in the engine compartment, road noise generated during driving, and wind whistle sound, from entering the car cabin through the door seal. The acoustic insulation material, when in use, is fitted onto the cross section of the front fender of the car. The acoustic insulation material uses a cushion material that has a predetermined density. The cushion material is either coated with a film or not coated with any film, but subjected to waterproof treatment.

As described in JP-U-3048125, the special cushion material that has a predetermined density is coated with a film or is subjected to waterproof treatment on the surface of the cushion material. However, this causes an increase in costs of the cushion material, an increase in number of parts, and an increase in processing costs and management costs.

SUMMARY OF THE INVENTION

The present invention provides a low-cost vehicle sound absorption structure.

A first aspect of the present invention is related to a vehicle sound absorption structure that has: a recessed cell that has an opening on one end thereof; a divider that is provided within the cell and that divides an acoustic wave entering the cell from the opening into two acoustic waves; reflectors that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave; and an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been reflected respectively at the reflectors, to interfere with each other.

According to the first aspect of the invention, an acoustic wave enters the cell from the opening of the cell and is divided at the divider into two acoustic waves. When the two acoustic waves are reflected respectively at the reflectors, a phase difference is generated between the one acoustic wave and the other acoustic wave. The one acoustic wave and the other acoustic wave interfere with each other at the interfering portion, while having the phase difference, so that a sound absorption effect is produced. This allows the vehicle sound absorption structure to be provided at low cost without increasing the number of parts.

According to the first aspect of the invention, an end of the divider on the side of the opening may be positioned more inward in the cell than the opening and positioned closer to the opening than one of the reflectors. The one of the reflectors may be positioned closer to the opening than the other reflector. The interfering portion may be positioned between the end and the opening.

As described above, the vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of providing the low-cost vehicle sound absorption structure.

In the above aspect, the divider may have an end on the side of the opening and positioned more inward in the cell than the opening, while being positioned closer to the opening than one of the reflectors, the one of the reflectors being positioned closer to the opening than the other reflector. And, the interfering portion may be positioned between the opening and the end of the divider. This allows an acoustic wave that enters the cell to be absorbed in the cell.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of producing the sound absorption effect in the cell in a stable manner.

In the first aspect of the invention, the vehicle sound absorption structure may further include a cover member that covers the opening. The cover member may have a slit that is provided on an extension of the divider.

According to the first aspect of the invention, when incident acoustic waves obliquely to the depth direction of the cell enter the cell through the slit, the acoustic waves become in phase due to a diffraction phenomenon through the slit. This ensures that the one acoustic wave and the other acoustic wave that are divided at the divider have a desired phase difference therebetween. Therefore, the vehicle sound absorption structure has improved sound absorption performance with respect to the acoustic wave frequency of the sound to be absorbed.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of improving the sound absorption performance with respect to the acoustic wave frequency of the sound to be absorbed.

In the first aspect of the invention, the slit may extend in a direction along the end of the divider.

As described above, the slit extends in a direction along the end of the divider. Thus, when acoustic waves enter the cell through the slit, the acoustic waves become in phase over a wide frequency range due to a diffraction phenomenon. Therefore, the vehicle sound absorption structure has further improved sound absorption performance with respect to the acoustic wave frequency of the sound to be absorbed.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of further improving the sound absorption performance with respect to the acoustic wave frequency of the sound to be absorbed.

In the first aspect of the invention, the cell may be partitioned by a wall that includes a base part and the other part, and the base part may be thinner than the other part.

As described above, the cell is partitioned by a wall that includes a base part and the other part, and the base part is thinner than the other part. Thus, upon the entry of an acoustic wave into the cell, film resonance occurs on the wall that partitions the cell. Due to the film resonance, energy of the acoustic wave is converted into kinetic energy, so that the sound is absorbed. This further improves the sound absorption performance.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of further improving the sound absorption performance.

In the first aspect of the invention, the vehicle sound absorption structure may also serve as a fender protector that shields a gap between a vehicle body framework and a rear end of a front fender panel, the rear end being positioned inner side of the vehicle. The opening may be formed toward the front side of the vehicle.

The vehicle sound absorption structure according to the first aspect of the invention also serves as a fender protector, and the opening is formed toward the front side of the vehicle. This allows noise from a front tyre to be absorbed without increasing the number of parts.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of absorbing the noise from the front tyre without increasing the number of parts.

In the first aspect of the invention, the vehicle sound absorption structure may be provided on a front surface of the fender protector that shields the gap between the vehicle body framework and the rear end of the front fender panel, in which the front surface faces toward the front side of the vehicle, and the rear end is positioned inner side of the vehicle.

As described above, the vehicle sound absorption structure is provided on the front surface of the fender protector, the front surface facing toward the front side of the vehicle. This enables the noise from the front tyre to be absorbed.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of absorbing road noise from the front tyre.

In the first aspect of the invention, the vehicle sound absorption structure may be formed in combination with the fender protector. The front surface of the fender protector may be utilised as the reflectors, and the front surface faces toward the front side of the vehicle.

As described above, the front surface of the fender protector is utilised as the reflectors. This enables reductions in material costs of and in weight of the vehicle-sound absorption structure, compared to the case when the reflector is continuously formed with a wall of the cell.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of reducing the material costs and the weight, compared to the case when the reflector is continuously formed with a wall of the cell.

In the first aspect of the invention, the vehicle sound absorption structure may also serve as at least one of an engine cover and a floor under cover.

In the first aspect of the invention, the vehicle sound absorption structure may also serve as a fender liner that is formed on an inside of the front fender panel to cover the front tyre. The opening may be formed toward the front side of the vehicle.

In the first aspect of the invention, a plurality of the cells may be arranged in parallel in a vertical direction with the opening of each of the cells facing toward the front side of the vehicle. Communicating holes communicate with a lower adjacent one of the cells may be formed on lower walls of the cells.

As described above, a plurality of the cells are arranged in parallel in a vertical direction with the opening of each of the cells facing toward the front side of the vehicle. This allows the sound absorption effect to be produced in a wide region. In addition, the cells each have lower walls through which communication holes are formed. The communication holes communicate with a lower adjacent one of the cells. This provides an additional function as an expansion silencer. Further, water in the cell can be drained through the communication holes. This further improves the sound absorption performance, while preventing the water from remaining in the cell to maintain the sound absorption performance.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of further improving the sound absorption performance, while preventing the water from remaining in the cell to maintain the sound absorption performance.

In the first aspect of the invention, the lower walls may be angled downwardly to the front side of the vehicle.

As described above, the lower walls of the cell are angled downwardly to the front side of the vehicle. This makes it difficult for the water to remain in the cell.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of making it difficult for the water to remain in the cell.

In the first aspect of the invention, the communication holes may be provided on the lower walls at respective ends that face toward the rear side of the vehicle.

As described above, the communication holes are provided on the lower walls at respective ends that face toward the rear side of the vehicle. Thus, when the vehicle is accelerating, the water in the cell flows toward the rear side of the vehicle to be efficiently discharged out of the cell through the communication holes.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of efficiently discharging the water flowing in the cell toward the rear side of the vehicle out of the cell through the communication holes when the vehicle is accelerating.

In the first aspect of the invention, the vehicle sound absorption structure may further include a Helmholtz resonator that is provided adjacent to the cells and that has a neck and a cavity, and the neck may be open in the same direction as the opening. The neck may be an opening of the Helmholtz resonator. This opening may be defined by the walls.

According to the first aspect of the invention, the Helmholtz resonator is provided adjacent to the cells to further improve the sound absorption performance.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of further improving the sound absorption performance by using the Helmholtz resonator that is provided adjacent to the cells.

In the first aspect of the invention, a volume of the cavity, a diameter of the neck or a length of the neck may be varied in order to adjust sound-absorption characteristics of the Helmholtz resonator.

In the first aspect of the invention, the cavity may be formed into a trapezium or trapezoid shape.

In the first aspect of the invention, the vehicle sound absorption structure may further has: a primary tubular passage that is provided adjacent to the cells and is open toward the same direction as the opening; and a secondary tubular passage that is branched from the primary tubular passage at a midsection of the primary tubular passage and that rejoins the primary tubular passage at a point where the primary tubular passage and the secondary tubular passage join together. The primary tubular passage and the secondary tubular passage may respectively have predetermined lengths such that an acoustic wave passing through the primary tubular passage alone and another acoustic wave passing through the primary tubular passage via the secondary tubular passage have a phase difference therebetween at the point where the primary tubular passage and the secondary tubular passage join together.

As described above, the acoustic wave passing through the primary tubular passage alone and the another acoustic wave passing through the primary tubular passage via the secondary tubular passage have a phase difference therebetween, and then interfere with each other at the point where the primary tubular passage and the secondary tubular passage join together. Consequently, the sound absorption effect is produced. This still further improves the sound absorption performance.

The vehicle sound absorption structure according to the first aspect of the invention has an excellent effect of still further improving the sound absorption performance.

A second aspect of the present invention is related to a front fender structure that has: a front fender panel; a fender protector that shields a gap between a vehicle body framework and a rear end of the front fender panel, the rear end facing toward the inner side of the vehicle; and a vehicle sound absorption structure according to the first aspect of the invention, the vehicle sound absorption structure being mounted onto a front surface of the fender protector with the opening facing toward the front side of the vehicle, the front surface facing toward the front side of the vehicle.

According to the second aspect of the invention, noise from the front tyre is absorbed at low cost.

The vehicle sound absorption structure according to the second aspect of the invention has an excellent effect of absorbing noise from the front tyre at low cost.

In the second aspect of the invention, a plurality of the cells may be arranged in parallel in the vertical direction, the cells may each have lower walls through which communication holes are formed, and the communication holes may communicate with a lower adjacent one of the cells.

As described above, a plurality of the cells are arranged in parallel in the vertical direction. This allows the sound absorption effect to be produced in a wide region. In addition, the cells each have lower walls through which communication holes are formed. The communication holes communicate with a lower adjacent one of the cells. This provides an additional function as an expansion silencer. Further, water in the cell can be drained through the communication holes. This further improves the sound absorption performance, while preventing the water from remaining in the cell to maintain the sound absorption performance.

The vehicle sound absorption structure according to the second aspect of the invention has an excellent effect of further improving the sound absorption performance, while preventing the water from remaining in the cell to maintain the sound absorption performance.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a perspective view of a vehicle sound absorption structure according to a first embodiment of the invention, when viewed from the front side of the vehicle;

FIG. 2 is a perspective view of the vehicle sound absorption structure according to the first embodiment of the invention, when viewed from the rear side of the vehicle;

FIG. 3 is an enlarged sectional view of the vehicle sound absorption structure according to the first embodiment of the invention;

FIG. 4 is an enlarged sectional view of the vehicle sound absorption structure that illustrates a sound absorption effect within a cell;

FIG. 5 is an enlarged sectional view of a modification of the vehicle sound absorption structure according to the first embodiment of the invention;

FIG. 6 is a chart that illustrates the relationship between a frequency and a sound absorption coefficient;

FIG. 7 is a perspective view of a front fender structure that uses the vehicle sound absorption structure according to the first embodiment of the invention;

FIG. 8 is a sectional view of the front fender structure;

FIG. 9 is an enlarged perspective sectional view of the vehicle sound absorption structure according to a second embodiment of the invention;

FIG. 10 is a chart that illustrates the relationship between a frequency and a sound absorption coefficient;

FIG. 11 is an enlarged sectional view of the vehicle sound absorption structure according to a third embodiment of the invention;

FIG. 12 is a sectional view that illustrates film resonance that occurs on walls;

FIG. 13 is an enlarged sectional view of the vehicle sound absorption structure according to a fourth embodiment of the invention;

FIG. 14 is an enlarged sectional view of a modification of the vehicle sound absorption structure according to the fourth embodiment of the invention;

FIG. 15 is an enlarged sectional view of another modification of the vehicle sound absorption structure according to the fourth embodiment of the invention;

FIG. 16 is a chart that illustrates the relationship between a frequency and a sound absorption coefficient;

FIG. 17 is an enlarged sectional view of the vehicle sound absorption structure according to a fifth embodiment of the invention;

FIG. 18 is a perspective sectional view of the vehicle sound absorption structure according to a sixth embodiment of the invention;

FIG. 19 is a schematic view of an expansion silencer;

FIG. 20 is a sectional view of the front fender structure in which the vehicle sound absorption structure according to extends2613on an inner side of the vehicle. The fender protector 28 is secured to the front fender panel 36 at its rear end 36A and to the vehicle body framework 46 on its forward side of the vehicle, using, for example, an adhesive 54.

The vehicle sound absorption structure 10 is provided on the front surface 28A of the fender protector 28 such that the plural cells 12 are arranged in parallel in the vertical direction with their respective openings 24 facing toward the front side of the vehicle. This allows the sound absorption effect to be produced in a wide region, thus to efficiently absorb noise from the front tyre 44 at low cost.

(Further Other Embodiment) illustrated Illustrated as a further modification of the vehicle sound absorption structure 10 in FIG. 21, the cell 12 may be open on its rear end side to be shielded by a separate member such that the separate member may be utilised as the reflector 18. The separate member is, for example, the fender protector 28. In other words, the vehicle sound absorption structure 60 according to the sixth embodiment is not limited to the configuration illustrated in FIG. 18 in which the rear part of the vehicle sound absorption structure 60 is shielded by the wall 38 that is continuously formed with the wall 26 of the cell 12.

According to the further modification, the front surface 28A of the fender protector 28 is utilised as the reflector 18. This enables reductions in material costs of and in weight of the vehicle sound absorption structure 10, compared to the case when the reflector 18 is continuously formed with the wall 26 of the cell 12. As illustrated in FIG. 22, the walls 26 and 96 may have notches at their respective rear ends, and these rear ends may be shielded by a separate member (fender protector 28). This facilitates forming of the communication holes 100. Therefore, the vehicle sound absorption structure 60 has improved formability.

While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.

Claims

1. A vehicle sound absorption structure comprising:

a recessed cell that has an opening on one end thereof;

a divider that is provided within the cell and that divides an acoustic wave entering the cell from through the opening into two acoustic waves;

reflectors provided adjacent to the divider that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave; and

an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been respectively reflected at the reflectors, to interfere with each other; and

a cover member that covers the opening and which opening, wherein the cover member has a slit provided on an extension of that is aligned with the divider.

2. The vehicle sound absorption structure according to claim 1, wherein:

the divider has an end on a side of that faces the opening and positioned more inward in the cell than the opening, while being positioned closer to the opening than one of the reflectors, the one of the reflectors being positioned closer to the opening than the other reflector; and

the interfering portion is positioned between the end and the opening.

3. The vehicle sound absorption structure according to claim 2, wherein the slit extends in a direction along the end of the divider.

4. The A vehicle sound absorption structure according to claim 1, comprising:

a recessed cell that has an opening on one end thereof;

a divider that is provided within the cell and that divides an acoustic wave entering the cell through the opening into two acoustic waves;

reflectors provided adjacent to the divider that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave;

an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been respectively reflected at the reflectors, to interfere with each other;

a cover member that covers the opening,

wherein the cell is the vehicle sound absorption structure further comprises a plurality of cells, adjacent cells being partitioned by a wall that includes a base part and the an other part, the base part being thinner than the other part.

5. The vehicle sound absorption structure according to claim 1, wherein:

the vehicle sound absorption structure also serves as a fender protector that shields a gap between a vehicle body framework and a rear end of a front fender panel, the rear end being positioned inner side of the of a vehicle; and

the opening is formed toward the a front side of the vehicle.

6. The vehicle sound absorption structure according to claim 1, wherein the vehicle sound absorption structure is provided on a front surface of a fender protector that shields a gap between a vehicle body framework and a rear end of a front fender panel, a of a vehicle, the front surface facing toward the a front side of the vehicle, the rear end being positioned inner side of the vehicle.

7. The vehicle sound absorption structure according to claim 6 1, wherein:

the vehicle sound absorption structure is formed in combination with mounted on the fender protector; and

a front surface of the fender protector is utilised as one of the reflectors, the front surface facing toward the front side of the vehicle reflectors.

8. The vehicle sound absorption structure according to claim 1, wherein:

the vehicle sound absorption structure also serves as a fender liner that is formed on an inside of the front fender panel to cover a front tyre; and

the opening is formed toward the front side of the vehicle.

9. The A vehicle sound absorption structure according to claim 1, comprising:

a recessed cell that has an opening on one end thereof;

a divider that is provided within the cell and that divides an acoustic wave entering the cell through the opening into two acoustic waves;

reflectors provided adjacent to the divider that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave;

an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been respectively reflected at the reflectors, to interfere with each other;

a cover member that covers the opening,

10. The vehicle sound absorption structure according to claim 9, wherein the lower walls are angled downwardly to the front side of the vehicle.

11. The vehicle sound absorption structure according to claim 9, wherein the communication holes are provided on the lower walls at respective ends of the lower walls on the a rear side of the vehicle.

12. The vehicle sound absorption structure according to claim 1, further comprising a plurality of cells such that adjacent cells are partitioned by plural walls, a Helmholtz resonator that is provided adjacent to the cells and that has a neck and a cavity, the neck being open in the same direction as the opening, wherein the neck is defines an opening of the Helmholtz resonator, the opening of the Helmholtz resonator being defined by the walls.

13. The vehicle sound absorption structure according to claim 12, wherein a volume of the cavity, a diameter of the neck or a length of the neck is varied in order to adjust sound-absorption characteristics of the Helmholtz resonator.

14. The vehicle sound absorption structure according to claim 13 12, wherein the cavity is formed into a trapezium or trapezoid shape.

15. The vehicle sound absorption structure according to claim 1, further comprising:

a primary tubular passage that is provided adjacent to the cells cell and is open toward the same direction as the opening; and

a secondary tubular passage that is branched from the primary tubular passage at a midsection of the primary tubular passage and that rejoins the primary tubular passage at a point where the primary tubular passage and the secondary tubular passage join together,

wherein the primary tubular passage and the secondary tubular passage respectively have predetermined lengths such that an acoustic wave passing through the primary tubular passage alone and another acoustic wave rejoining the primary tubular passage via the secondary tubular passage have a phase difference therebetween at the point where the primary tubular passage and the secondary tubular passage join together.

16. A front fender structure of a vehicle comprising:

a front fender panel;

a fender protector that shields a gap between a vehicle body framework and a rear end of the front fender panel, the rear end being positioned inner side of the vehicle; and

a vehicle sound absorption structure according to claim 1,

wherein the vehicle sound absorption structure being mounted onto a surface of the fender protector with the opening facing toward the a front side of the vehicle, the surface facing toward the front side of the vehicle, wherein a plurality of the cells are arranged in parallel in a vertical direction, and the cells each have lower walls through which communication holes are formed, the communication holes communicating with a lower adjacent one of the cells.

17. The vehicle sound absorption structure according to claim 1, wherein the reflectors comprise a first reflector and a second reflector, the first reflector is disposed at a different depth with respect to the opening than the second reflector.

18. The vehicle sound absorption structure according to claim 1, wherein the slit extends in a same direction as the divider.

19. A front fender structure of a vehicle comprising:

a front fender panel;

a fender protector that shields a gap between a vehicle body framework and a rear end of the front fender panel; and

a vehicle sound absorption structure comprising:

a recessed cell that has an opening on one end thereof;

a divider that is provided within the cell and that divides an acoustic wave entering the cell through the opening into two acoustic waves;

reflectors provided adjacent to the divider that reflect one of the two acoustic waves divided at the divider and reflect the other acoustic wave respectively toward the opening, and that generate a phase difference between the one acoustic wave and the other acoustic wave;

an interfering portion that is provided within the cell and that causes the one acoustic wave and the other acoustic wave, which have been respectively reflected at the reflectors, to interfere with each other; and

a cover member that covers the opening,

wherein:

the vehicle sound absorption structure being mounted onto a surface of the fender protector with the opening facing toward a front side of the vehicle, the surface facing toward the front side of the vehicle, and

a plurality of cells are arranged in parallel in a vertical direction, and the cells each have lower walls through which communication holes are formed, the communication holes communicating with a lower adjacent one of the cells.