JP2000272439A - Sound insulating front grille panel, sound absorbing bumper and outside-car noise reducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce a noise radiated ahead of a vehicle from an engine room while ensuring ventilation of the engine room. SOLUTION: A sound insulating front grille panel 1 is provided with two sheets of plate material parts 11, 12 having many through-holes 10, cylinder member 13 directly connecting a half number of the through-holes 10, and an air chamber 14 connecting the rest of half number of the through-holes 10. A resonance frequency of the air chamber 14 is lower than 1 kHz, a component exceeding the resonance frequency of noises permeating the air chamber 14 generates a reverse phase, to offset a component of approx. 1 kHz of noise passing through the cylinder member 13. Consequently, a main component of noise with the central frequency of approx. 1 kHz leaking out to the forward from an engine room which is sound-proved by a sound absorbing material or the like, can be reduced while holding ventilation to the engine room. A resonator opened to the engine room is arranged in a recessed part in a reverse side of a bumper, and similarly noise of approx. 1 kHz can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of noise reduction technology for vehicles including vehicles.

[0002]

2. Description of the Related Art In a conventional vehicle, a sound insulating material or a sound absorbing material represented by an engine head cover or a rubber spacer is disposed in an engine room in order to absorb noise generated in an engine room. By the action of such a sound insulating material or a sound absorbing material, a noise reduction effect is exerted mainly in a high sound frequency band exceeding 1 kHz (mainly 2 kHz or more).

Further, Japanese Patent Application Laid-Open Nos. Hei 7-175485 and Hei 7-13573 disclose a sound-insulating wall having high air permeability used as an undercover of an engine room of a vehicle. According to the techniques disclosed in these publications, it is possible to obtain the effect of ensuring ventilation and preventing the engine room from being heated while reducing noise radiated downward from the vehicle.

[0004]

However, the technique of arranging a normal sound insulating material or a sound absorbing material in an engine room cannot obtain a very high noise reduction effect in a frequency band around 1 kHz. Also, even with the techniques of the above-mentioned publications, the effect of reducing the noise radiated toward the front of the vehicle is hardly obtained. Therefore, it is a fact that an effective noise reduction effect is not obtained for noise in a frequency band near 1 kHz among noises radiated forward from the engine room. In addition, in many automobiles, the peak of the noise spectrum emitted from the engine room is formed at around 1 kHz, and therefore, it is important to reduce the noise around 1 kHz to reduce the noise outside the vehicle.

[0005] Therefore, the present invention is to solve the problem of providing a means capable of effectively reducing the noise radiated from the engine room to the front of the vehicle while ensuring the ventilation to the engine room. I do.

[0006]

In order to solve the above problems, the inventor has invented the following means. [Sound Insulating Front Grill Panel] (First Means) A first means of the present invention covers at least a part of the front of an engine room provided at a front portion of a vehicle, and has a large number of through holes formed therein so as to provide an appropriate interval. A sound-insulating front grill panel having two plate members arranged in a space.

In this means, a panel attached to or integrated with a front grille which covers the front of the engine room and has excellent air permeability has two through holes formed at appropriate intervals and formed with a large number of through holes. It has a plate part. Therefore, not only the air permeability is ensured by the large number of through holes, but also the air in the space formed between the two plate members forms an air spring, and a noise in a frequency band exceeding its resonance frequency is generated. Particularly effective in providing a sound-insulating effect.
No. 13573). Thus, if the resonance frequency is set to less than 1 kHz by appropriately adjusting the distance between the two plate members and the size of the through-hole, noise near 1 kHz can be effectively isolated.

Therefore, according to this means, there is an effect that the noise radiated from the engine room to the front of the vehicle can be effectively reduced while ensuring the air permeability to the engine room. (Second Means) A second means according to the first means, wherein the cylindrical member that directly communicates a part of the through holes of the plate members and the air that communicates the other through holes with each other. It is characterized by having a room.

In this means, the noise (the former) that has exited the vehicle through the through-hole communicated by the cylindrical member keeps its original phase, and resonance occurs among the noise that exits the vehicle through the through-hole communicated by the air chamber. The components above the frequency (the latter) are in opposite phase. Therefore, at the stage where they go out of the vehicle and are mixed, components of the former which are equal to or higher than the resonance frequency are offset by the latter, and outside the vehicle, noise in the frequency band equal to or higher than the resonance frequency is significantly reduced (such an effect is obtained). Japanese Patent Application Laid-Open No. 7-175
No. 485). Therefore, if the resonance frequency of the air chamber is set to less than 1 kHz by properly adjusting the distance between the two plate members and the size of the through hole, the noise around 1 kHz can be more effectively shielded. become.

Therefore, according to this means, in addition to the effect of the above-described first means, there is an effect that the noise component of the air chamber having the resonance frequency or higher is more effectively reduced. (Third Means) A third means of the present invention is characterized in that, in the first means, the front grille is formed integrally with a front grill covering the front of the engine room.

In this means, since the front grill and the sound-insulating front grill panel are integrally formed, the space in the engine room is larger than when both are provided separately, and the design around the engine room and in the engine room is improved. Becomes easier. Further, for the same reason, the weight can be reduced as compared with the case where both are provided separately. In addition, the number of assembly steps required to equip the sound insulation front grill panel behind the front grill is reduced, and the cost of parts is reduced due to the reduction in the number of parts, resulting in a lower cost than when both are installed separately. become.

Therefore, according to this means, in addition to the effect of the first means described above, there are effects that the restrictions on the design of the engine room are reduced, and that the weight and cost of the vehicle can be reduced. [Sound Absorbing Bumper] (Fourth Means) A fourth means of the present invention is directed to a bumper having a concave portion which covers a lower front of an engine room provided at a front portion of a vehicle and has an opening toward the engine room. A sound-absorbing bumper having at least one of a housed resonator and a quarter-wave acoustic tube. Here, the resonator or the quarter-wavelength acoustic tube need not necessarily be entirely housed in the recess of the bumper body, and is included in the present means if at least a part is housed in the recess of the bumper body. Shall be. Also, a quarter-wavelength acoustic tube is a resonance tube that has a quarter of the length corresponding to the wavelength of the frequency component of the noise to be suppressed, and the end opposite to the open end is closed. Tube.

In the present means, a resonator (resonator)
Is open toward the engine room, components of the noise incident on the resonator from the engine room that are higher than the resonance frequency of the resonator are reflected in the opposite phase. Therefore, a component higher than the resonance frequency in the noise of the engine room is canceled by the reflected wave from the resonator, and the noise level is effectively reduced.

In the case where the quarter-wavelength acoustic tube is open toward the engine room, of the noise incident on the quarter-wavelength acoustic tube from the engine room, the quarter-wavelength acoustic tube may be used. A component having a wavelength four times as long as the wavelength is reflected in an opposite phase to that at the time of incidence. Therefore, a component of the noise in the engine room having a wavelength four times the length of the quarter-wavelength acoustic tube is canceled by the reflected wave from the quarter-wavelength acoustic tube, and the noise level is reduced. .

Since at least a part (preferably all) of the resonator or the quarter-wavelength acoustic tube is housed in a concave portion formed at the rear of the bumper main body, it is difficult to narrow the engine room. Not so much. Therefore, according to this means, there is an effect that the noise emitted forward from the engine room can be effectively reduced without making the engine room too narrow. Since the concave portion of the bumper main body does not originally have air permeability, the air permeability to the engine room is not impaired by this means, and the air permeability to the engine room is kept good.

(Fifth Means) According to a fifth means of the present invention, in the fourth means, the resonator or the quarter-wavelength acoustic tube is formed integrally with the bumper. In this means, since the resonator or the quarter-wave acoustic tube is integrally formed with the bumper main body, the protrusion into the engine room is reduced as compared with the case where both are provided separately, and the space in the engine room is expanded. Design around the engine room and inside the engine room becomes easy. Further, for the same reason, the weight can be reduced as compared with the case where both are provided separately. Furthermore, the number of assembling steps for mounting the resonator and the like in the concave portion of the bumper main body can be reduced, and the cost of the parts can be reduced as compared with the case where both are provided separately, together with the reduction in the parts price due to the reduction in the number of parts.

Therefore, according to this means, in addition to the effect of the above-described fourth means, there are effects that the restrictions on the design of the engine room are reduced, and that the weight and cost of the vehicle can be reduced. (Sixth Means) A sixth means of the present invention is a two-plate material having an opening for taking air into the engine room, a large number of through holes formed in the opening, and arranged at appropriate intervals. It is a sound-absorbing bumper characterized by having a part.

In this means, since the sound-insulating panel having the same sound insulation function as the first means is attached to the opening of the air intake of the bumper, the noise emitted forward from the opening of the bumper is provided. Is reduced. Therefore, according to this means, in a bumper having an opening for taking in air, there is an effect that noise emitted forward from the engine room through the opening of the bumper is reduced.

[External Noise Reduction Apparatus] (Seventh Means) The seventh means of the present invention is a sound insulating front grill panel of the first means, a sound absorbing bumper of the fourth means, and a sound absorbing bumper of the sixth means. An external noise reduction device characterized by having at least one of them.

In this means, the combination of the sound-insulating front grille panel and the sound-absorbing bumper is provided in front of the engine room of the vehicle. A noise reduction effect is obtained. In particular, when the sound-insulating front grill panel of the second means and the sound-absorbing bumper of the fourth means are combined, a synergistic effect is obtained, and an even greater external noise reduction effect is stably obtained. It has been clarified.

Therefore, according to this means, it is possible to more effectively reduce the noise outside the vehicle while securing the air permeability to the engine room, as compared with the case where the sound insulating front grill panel or the sound absorbing bumper is provided alone. There is an effect that can be.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the sound insulating front grill panel, the sound absorbing bumper and the vehicle exterior noise reduction device of the present invention will be described in the following examples so that those skilled in the art can understand the present invention. Explain fully. [Example 1] (Sound-insulating front grill panel of Example 1) The sound-insulating front grill panel 1 of Example 1 of the present invention includes a front part of an engine room provided at a front part of a vehicle and a rear part of the front grille. It is a perforated panel to cover. That is, as shown in FIG. 1, the sound insulating front grill panel 1 of the present embodiment includes two plate members 11, 12 formed with a large number of through holes 10 and arranged in parallel at appropriate intervals. Have. Then, as shown in FIG.
3 has an air chamber 14 that allows the other through-holes 10 to communicate with each other, as shown in FIG. The resonance frequency of the air chamber 14 is described in
According to the calculation method disclosed in JP-A-175485, the frequency is about 590 Hz.

Here, as shown in FIG.
The five portions A having the through holes 10 communicating with each other by 3 are vertically arranged at equal intervals, and the five portions B having the through holes 10 communicating with each other by the air chamber 14 are also arranged at five vertical portions. They are arranged at intervals. The portions A and B are alternately arranged in the left-right direction. Therefore, each through hole 1
Through 0, considerable air permeability is secured.

The sound insulating front grill panel 1 of the present embodiment
In this case, the noise (the former) that goes forward of the vehicle through the part A keeps the original phase, but the component (the latter) having the resonance frequency or higher in the noise that goes forward of the vehicle through the part B has the opposite phase. . Therefore, at the stage where they are mixed out of the vehicle, the components above the resonance frequency of the former are canceled by the latter, and outside the vehicle, the noise in the frequency band above the resonance frequency is greatly reduced. That is, the space between the two plate members 11 and 12 and the size of the through hole 10 are appropriate, and the air chamber 1
Since the resonance frequency of No. 4 is set to about 590 Hz which is less than 1 kHz, noise near 1 kHz is effectively shielded by the sound insulating front grille panel 1 of this embodiment.

Therefore, according to the sound-insulating front grille panel 1 of the present embodiment, the component in the frequency band near 1 kHz of the noise radiated from the engine room to the front of the vehicle while ensuring the air permeability to the engine room. Can be effectively reduced. (Sound Absorbing Bumper of First Embodiment) The sound absorbing bumper of the first embodiment is a bumper having a concave portion that covers a lower front of an engine room provided at a front portion of a vehicle and has an opening toward an engine room. And a resonator that is housed in the vehicle and opens toward the engine room. That is, the sound-absorbing bumper (not shown) of the present embodiment has an opening for taking in air into the engine room at an intermediate portion in the vertical direction. In the upper half recess, two resonators 2 shown in FIGS. 4A to 4C are accommodated in series in a horizontal direction, and in the lower half recess, FIGS. (C) Two resonators 2 'shown in FIG.

As shown in FIGS. 4A and 4B, the resonator 2 includes a pipe portion 21 forming an opening 20 and a partition member 22 forming a resonance chamber 23. Here, assuming that the air accommodated in the pipe portion 21 is a mass and the air accommodated in the resonance chamber 23 forms an air spring, the resonance frequency f ₀ of the resonator 2 is expressed by the following _{equation (} 1). It is calculated.

[0027]

F ₀ = (c / 2π) √ (S / lV) where c: sound velocity, S: cross-sectional area of pipe part 21, l: length of pipe part 21, V: inside of resonance chamber 23 Volume.
When the resonance frequency is obtained in accordance with the equation (1), assuming that the sound speed is that at room temperature, the resonance speed is about 680 Hz, about 780 Hz, about 960 Hz, about 1
140 Hz.

On the other hand, the resonator 2 'is shown in FIG.
As shown in (C), the partition member 2 forming the resonance chamber 23
The basic configuration is the same as that of the resonator 2 described above, except that the bottom surface of the resonator 2 is formed obliquely to the noise incident direction. Such a difference in shape is merely a result of designing the bumper body to fit in the lower half recess because the shape of the lower half recess is oblique, unlike the shape of the upper half recess. Therefore, the resonance frequency f ₀ of the resonator 2 ′ is calculated in the same manner as in the above _{equation (} 1).
Approx. 720 Hz, approx. 82
0 Hz, about 1020 Hz, and about 1250 Hz.

In this embodiment, since each of the resonators 2 and 2 'housed in the concave portion of the bumper body is open toward the engine room, each of the noises incident on each of the resonators 2 and 2' from the engine room. Resonator 2,
Components higher than each resonance frequency of 2 'are reflected out of phase. Therefore, the components of the noise in the engine room higher than the resonance frequency are equal to each of the resonators 2 and 2 ′.
And the noise level is effectively reduced.

In this embodiment, each of the resonators 2,
Since the entire 2 'is housed in the recess formed behind the bumper main body, the sound absorbing bumper of this embodiment does not narrow the engine room. Therefore, according to the sound absorbing bumper of the present embodiment, there is an effect that the noise emitted forward from the engine room can be effectively reduced without making the engine room narrow. In addition, since the concave portion of the bumper body does not originally have air permeability, the sound absorbing bumper of this embodiment does not impair the air permeability to the engine room, and the air permeability to the engine room is kept good. It is.

(External Noise Reduction Apparatus of First Embodiment) First Embodiment
In the vehicle exterior noise reduction device, both the sound-insulating front grill panel of the first embodiment and the sound-absorbing bumper of the first embodiment are provided in front of the engine room of the vehicle. (Demonstration of noise reduction effect of Embodiment 1) In this embodiment,
Sound insulation front grill panel 1, resonator 2,
The sound absorbing bumper provided with 2 ′ exhibits a noise reduction effect as shown in FIGS. Here, the horizontal axis of both figures is the center frequency of the frequency band divided by 1/2 octave, and the vertical axis of both figures is the sound pressure level of the noise in the frequency band represented by the center frequency. Is measured 1 m in front of the front grill of the stopped test vehicle.

First, the sound-insulating front grille panel 1 of this embodiment is provided between the front grille and the radiator of an RV diesel engine vehicle as a vehicle, and the bumper is equipped with a normal bumper. The noise was actually measured. In this case, as shown in FIG. 6, compared to the sound pressure level measured in the vehicle in the base state not equipped with the present embodiment, the frequency band around 1 kHz of about 0.8 kHz to 1.6 kHz is distinct. The noise reduction effect has been demonstrated. Then, at the peak of the sound pressure level of the noise near 1 kHz, the same sound pressure level is 5.
2 dB has also been reduced.

Next, the same automobile is not equipped with the sound insulating front grille panel 1, and the resonators 2 and 2 'of this embodiment are not provided.
The sound pressure level was actually measured in the same manner with only the attached sound absorbing bumper. As a result, as shown in FIG.
A significant noise reduction effect is exhibited in the frequency band of z to 1.6 kHz. At the peak of the sound pressure level near 1 kHz, the sound pressure level is reduced by 1.6 dB.

Finally, the same automobile was equipped with both the sound insulating front grille panel 1 of the present embodiment and the sound absorbing bumper to construct an outside noise reduction device of the present embodiment, and the noise was measured. As a result, as shown in FIG. 7, the sound pressure level is 0.8 kHz to 1.
A remarkable noise reduction effect is exhibited in a frequency band around 1 kHz of about 6 kHz. Then, at the peak of the sound pressure level of the outside noise near 1 kHz, a noise reduction effect of 7.0 dB in the sound pressure level is observed. Even in a higher frequency band, around 2.6 kHz or 4 kHz
A significant noise reduction effect around z can be seen from FIG.

That is, in the case of the vehicle exterior noise reduction device equipped with both the sound insulating front grille panel 1 and the sound absorbing bumper of the present embodiment, a synergistic effect of both can be obtained, and an effect obtained by simply adding both effects. It became clear that a bigger effect was exhibited. Also, the noise reduction effect can be obtained more stably as a synergistic effect of the two,
Confirmed experimentally.

In the overall value of the measured sound pressure level over the entire frequency band, when only the sound insulating front grill panel 1 of the present embodiment is provided, the noise reduction effect of 1.0 dB as compared with the base state is obtained. Obtained. Further, when only the sound absorbing bumper of the present embodiment was provided, a noise reduction effect of 0.6 dB was obtained as compared with the base state. Furthermore, when the vehicle exterior noise reduction device including both the sound insulating front grill panel 1 and the sound absorbing bumper of the present embodiment was provided, a noise reduction effect of about 1.6 dB was obtained as compared with the base state.

As described in detail above, according to the sound insulating front grille panel 1, the sound absorbing bumper and the vehicle exterior noise reduction device of the present embodiment, while ensuring the air permeability to the engine room, the front of the vehicle from the engine room can be secured. There is an effect that noise radiated to the vehicle can be effectively reduced. (Modification 1 of Embodiment 1) As Modification 1 of this embodiment, as shown in FIG.
Sound-insulating front grill panel 1 '
Can be implemented. And B which communicates with the air chamber 14
The part is surrounded by a part A penetrating the cylindrical member 13 on all sides, that is, six sides.

In this modified embodiment, the diameter of the through holes 10 is slightly smaller than that of the sound insulating front grill panel 1 of the first embodiment, but the sum of the cross-sectional areas formed by the respective through holes 10 is smaller than that of the sound insulating front grill panel. 1. Since the opening ratio occupying the entire front area is large, better air permeability is ensured. Further, the calculated value of the resonance frequency of the sound insulating front grille panel 1 'of this modification is about 860 Hz, so that good sound insulating characteristics can be obtained in a frequency band of about 0.9 kHz or more and around 1 kHz.

Therefore, according to this modified embodiment, the noise reduction effect similar to that of the sound insulating front grill panel 1 of the first embodiment described above and the effect that the air permeability better than that of the sound insulating front grill panel 1 are exhibited. There is. (Modification 2 of Embodiment 1) As Modification 2 of this embodiment, the above-described resonators 2 and 2 ′ are provided in the concave portions of the bumper main body.
Alternatively, an implementation of a sound absorbing bumper containing a quarter wavelength acoustic tube is possible. As shown in FIG. 9, the quarter-wavelength acoustic tube 3 of this modified embodiment includes a number of acoustic tubes 31 each having one end opened toward the engine room and the other end closed vertically. It is configured. Each acoustic tube 31
The depth of the internal space 30 formed is approximately 75 mm, and the quarter-wavelength acoustic tube 3 of this modified embodiment is designed so as to suppress noise at a frequency of about 1 kHz, which is the peak of noise in the engine room. Have been.

In the sound absorbing bumper of this modification, the quarter-wavelength acoustic tube 3 is open toward the engine room. A component of about 1 kHz having a wavelength four times the length of the one-wavelength acoustic tube is reflected in a phase opposite to that at the time of incidence. Therefore, a 1 kHz component having a wavelength four times the length of the quarter-wavelength acoustic tube 3 of the noise in the engine room is canceled by the reflected wave from the quarter-wavelength acoustic tube 3 and the noise level is reduced. Is reduced.

Therefore, the sound absorbing bumper according to the present modified example can also achieve a noise reduction effect similar to that of the sound absorbing bumper of the first embodiment. (Modification 3 of Embodiment 1) As a modification 3 of the present embodiment, instead of the sound insulating front grill panel 1 of Embodiment 1 manufactured separately from the front grill, a front grill that covers the front of the engine room is provided. An integrally molded sound insulating front grill panel is possible.

In the sound-insulating front grill panel of this modified embodiment, the two plate members need not be formed of flat plates, but are formed with curved surfaces in harmony with the front portion of the vehicle so as not to impair the aesthetic appearance of the vehicle. It is desirable to have been.
In addition, the interval between the two plate members does not need to be uniform, and it is sufficient if the design is made in consideration of the external shape, the manufacturing cost, and the resonance frequency. Further, the cross-sectional shape of the through-hole does not need to be circular, and it is sufficient if the through-hole is designed in consideration of the external shape, the manufacturing cost, and the resonance frequency.

In this modification, the front grille and the sound-insulating front grille panel are integrally formed, so that the space in the engine room is larger than when both are provided separately, and the surroundings of the engine room and in the engine room are increased. Design becomes easier. Further, for the same reason, the weight can be reduced as compared with the case where both are provided separately. In addition, the number of assembly steps required to equip the sound insulation front grill panel behind the front grill is reduced, and the cost of parts is reduced due to the reduction in the number of parts, resulting in a lower cost than when both are installed separately. become.

Therefore, according to the sound-insulating front grill panel of this modified embodiment, in addition to the effects of the first embodiment, the restrictions on the design of the engine room are reduced as compared with the first embodiment, and the weight and cost of the vehicle are reduced. There is an effect that can be down. (Modification 4 of Embodiment 1) As Modification 4 of the present embodiment, it is possible to implement a sound absorbing bumper in which the resonators 2 and 2 'of Embodiment 1 are formed integrally with the bumper body.

In the sound-absorbing bumper according to this modification, a large number of pipe-shaped through holes are formed to cover the concave portion of the bumper body, and the curved plate material along the bumper body covers the concave portion of the bumper body. A resonance chamber is formed in the space between the main body and the bumper body. The resonance chamber does not necessarily need to be separated by a partition plate. If the resonance chamber is separated by a partition plate, the bumper body can be reinforced,
Without a partition plate, further weight reduction and cost reduction can be achieved.

The pipe connecting the resonance room and the engine room does not need to protrude toward the engine room. Therefore, if the sound absorbing bumper of the present modified embodiment is configured such that the pipe portion is housed in the resonance chamber, the vehicle can be equipped with the sound absorbing bumper of the present modified embodiment without narrowing the engine room at all. Alternatively, a simple configuration in which the pipe portion is omitted and a large number of through holes of an appropriate size are formed in the curved plate material may be used. Such a configuration can further reduce the cost and weight.

Further, assembling man-hours for mounting the resonator and the like in the concave portion of the bumper main body can be reduced, and the cost can be reduced as compared with the case where both are provided separately, in combination with the reduction in the component price due to the reduction in the number of components. become.
Therefore, according to the sound absorbing bumper of this modified embodiment, in addition to the effect of the sound absorbing bumper of the first embodiment, there is an effect that the weight and cost can be reduced as compared with the sound absorbing bumper of the first embodiment.

(Fifth Modification of the First Embodiment) As a fifth modification of the present embodiment, an opening for taking in air into the engine room is formed, and a large number of through holes are formed in the opening and are arranged at appropriate intervals. It is possible to implement a sound-absorbing bumper having two provided plate members. That is, in recent automobiles, an opening is formed not only in the gap of the front grill but also in a large bumper as an air intake to the engine room. Therefore, in the sound absorbing bumper having such an opening, it is possible to implement a sound absorbing bumper in which the opening is provided with a sound insulating panel similar to the above sound insulating front grill panel.

In the sound absorbing bumper of this modified embodiment, the sound insulating panel having the same sound insulating function as the sound insulating front grill panel of the first embodiment is also attached to the opening of the air intake port. The noise emitted forward from the part is also reduced. Nevertheless, a considerable degree of air permeability is ensured by the through holes formed in the sound insulating panel.

Therefore, according to the sound absorbing bumper of this modification, in addition to the effect of the sound absorbing bumper of the first embodiment,
There is an effect that noise emitted forward from the opening of the bumper is reduced. As a result, it is possible to obtain an effect that a more favorable noise reduction effect outside the vehicle can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a sound-insulating front grill panel according to a first embodiment.

FIG. 2 is a side sectional view of a portion A in FIG. 1;

FIG. 3 is a side sectional view of a portion B in FIG. 1;

FIG. 4 is a three side view showing one configuration of the resonator according to the first embodiment. (A) Front view (b) Plan view (c) Side view

FIG. 5 is a three-view drawing showing another configuration of the resonator of the first embodiment. (A) Front view (b) Plan view (c) Side view

FIG. 6 is a graph of a noise spectrum individually showing the effects of the first embodiment.

FIG. 7 is a noise spectrum graph comprehensively showing the effects of the first embodiment.

FIG. 8 is a front view showing a configuration of a sound-insulating front grill panel according to Modification 1.

FIG. 9 is a set diagram showing the configuration of a quarter-wavelength acoustic tube of Modification 2 (a) Front view (b) Plan sectional view

[Explanation of symbols]

1, 1 ': sound-insulating front grill panel 10: through hole 11, 12: plate member 13: cylindrical member 14: air chamber 2, 2': resonator 20: opening 21: pipe 22: partition member
23: resonance room 3: quarter-wavelength acoustic tube 31: acoustic tube 30: internal space

Claims (7)

[Claims] An engine room provided at a front portion of a vehicle has at least a portion in front of an engine room, a large number of through holes formed therein, and two plate members arranged at appropriate intervals. Features a sound-insulating front grill panel. 2. The sound-insulating front grill panel according to claim 1, further comprising: a tubular member that directly communicates a part of the through holes of the two plate members; and an air chamber that communicates the other through holes with each other. . 3. The sound insulating front grill panel according to claim 1, wherein the front grill panel is formed integrally with a front grill that covers the front of the engine room. 4. A bumper which covers a lower front of an engine room provided at a front part of a vehicle and has a concave portion opened toward the engine room, wherein the resonator and the quarter-wavelength acoustic tube housed in the concave portion. A sound-absorbing bumper having at least one of the following. 5. The sound-absorbing bumper according to claim 4, wherein the resonator or the quarter-wave acoustic tube is formed integrally with the bumper. 6. An engine compartment having an opening for taking in air, the opening having a plurality of through holes formed therein and having two plate members arranged at appropriate intervals. , Sound absorbing bumper. 7. A noise reduction outside a vehicle, comprising: the sound insulating front grill panel according to claim 1; and at least one of the sound absorbing bumper according to claim 4 and the sound absorbing bumper according to claim 6. apparatus.