JP3233328B2 - Sound insulation cover for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound insulating cover for a vehicle for preventing noise generated from equipment mounted on the vehicle from leaking.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 16 and 17, in a vehicle, particularly a truck equipped with a diesel engine, noise generated from an engine E or the like and its reflected sound are prevented from leaking outside the vehicle. Is installed. The sound insulating cover 7 includes a shielding plate 71 made of an iron plate or the like attached to the vehicle body frame 70 and a shielding plate 7
1 and a sound absorbing material 72 made of glass wool or the like attached to the inner surface of the base material 1.

[0003]

By the way, the above-mentioned sound insulating cover 7 is provided at the lower end of the sound insulating cover 7 in consideration of the minimum ground clearance of the vehicle which is set to prevent the abdomen of the vehicle from contacting the road surface A. Cannot be provided so as to extend to the vicinity of the road surface A, and is disposed such that a gap S is formed between the lower end of the sound insulating cover 7 and the road surface A. Therefore, a part of the engine sound or the noise reflected on the road surface A or the like leaks to the outside from the gap S, and the leakage of the noise cannot be completely prevented.

When noise passes through the vicinity of the end of the sound insulating cover 7 and leaks to the outside, as shown in FIG. 17, the noise diffracts due to the nature of the sound and goes around the outside of the sound insulating cover 7 to diffuse. I do. Therefore, when considering the effect of such a sound insulating cover (barrier), the Maekawa chart (1962, FIG. 18) obtained by experimentally correcting the result of the approximate calculation using the light diffraction theory is obtained. It is based. However, the theory of the Maekawa chart does not consider the thickness of the sound insulation cover.

However, when the thickness of the sound insulating cover is larger than the wavelength of the sound, the thickness of the sound insulating cover exerts a sound attenuating effect. Therefore, it is necessary to consider the thickness of the sound insulating cover. In this case, attenuation Att by sound insulation cover thickness b, the effect E of thickness attenuation Att ₀ without sound insulation cover thicknesses at the same height
T is added, and is represented by the following equation. _{Att = Att 0 + ET ET =} Klog (2πb / λ) (b> λ / 2) ≒ 0 (b ≦ λ / 2) where, lambda is the wavelength of sound, K is determined from FIG. 19 (a) Value. Incidentally, Att ₀ is the attenuation amount with respect to the path S ₁ EM in FIG 19 (b).

Accordingly, in order to attenuate the sound, it is possible to expect a further attenuating effect by increasing the thickness of the sound insulating cover in addition to increasing the length in the height direction. Therefore, the frequency of the sound to be reduced is mainly about 100
0 to 2000 Hz, the wavelength λ of the sound belonging to this range is defined as λ = C / f [C: sound velocity (about 340 mm /
sec), f: sound frequency (Hz)], the wavelength λ is 340 mm for 1000 Hz sound,
For a sound of 2000 Hz, the wavelength λ is 170 mm.

However, it is actually very difficult to make the thickness of the sound insulation cover attached to the vehicle 85 to 170 mm in view of the installation space and the like. On the other hand, from the viewpoint of environmental protection in recent years, further reduction of outside noise is desired. The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a sound insulation cover for a vehicle that can further reduce noise leaking from the periphery of the sound insulation cover to the outside of the vehicle. It is.

[0008]

Means for Solving the Problems Claims for solving the above problems
Item 1 is a sound insulation cover for a vehicle according to the invention, wherein the sound insulation cover is attached to a vehicle body and shields noise generated from equipment mounted on the vehicle, and a sound absorbing member is provided on at least a planar open end of the shield plate. and wood, made, sound absorbing material, said not covering at least the distal end surface of the open end portion of the shielding plate, and having a sound-absorbing part which is wider than the thickness width of the destination <br/> end face It is characterized by the following. The invention according to claim 2
The sound insulation cover for vehicles according to
Machine that has a curved part and is attached to the vehicle body and mounted on the vehicle
Shielding plate generated from the vessel, at least the shielding plate
A sound absorbing material provided in the curved portion,
At least the outer peripheral surface of the curved portion is covered, and the outer peripheral surface
It has a sound-absorbing part formed wider than its thickness.
It is a sign. According to the third aspect of the present invention,
The sound insulation cover for vehicles has a bent portion at the open end,
Blocks noise from equipment mounted and mounted on the vehicle
A shielding plate to be shielded, and at least the bent portion of the shielding plate.
And a sound absorbing material that is bent,
And at least an outer surface of the outer surface, and a width greater than a thickness width of the outer surface
Characterized by having a widely formed sound absorbing part
is there.

The shielding plate in the present invention can be formed of a metal plate, a hard resin plate or the like. The sound absorbing material can be formed of a polymer material foam formed by foaming a polymer material such as polyurethane or silicone rubber, or a porous material such as glass wool. When the sound-absorbing material is formed of a polymer foam, it can be formed integrally with the shielding plate by integral molding, thereby enabling the sound-absorbing material of any shape to be formed and attached to the shielding plate at the same time. Therefore, the production of the sound insulation cover is simplified. This sound absorbing material can be provided not only on the sound absorbing portion provided at the open end of the shielding plate but also on the surface of the shielding plate on the noise source side.

The sound absorbing portion is disposed so as to cover at least the distal end surface of the open end of the shielding plate, the outer peripheral surface of the curved portion, or the outer surface of the bent portion, and has a thickness greater than the thickness of the distal end surface, the outer peripheral surface or the outer surface. It is formed wide. This sound-absorbing part is formed in a column shape or a mountain shape whose outer peripheral surface is an arc-shaped curved surface,
Alternatively, an appropriate shape can be selected, for example, by forming the outer peripheral surface into a prismatic shape having a flat surface. As a preferable mode of the sound absorbing portion, the distal end surface of the open end of the shielding plate, the outer periphery of the curved portion
The outer peripheral surface of the surface or the portion that covers the outer surface of the bent portion is formed by an arc surface. In another preferred embodiment, the length in the width direction of the outer peripheral surface of the sound absorbing portion is formed so as to be longer than the half wavelength of the frequency of the sound to be reduced.

[0011]

According to the sound insulating cover of the present invention, the noise that leaks from the gap formed around the open end of the sound insulating cover and that is diffracted by passing through the vicinity of the open end of the sound insulating cover is the open end of the shielding plate. The noise energy is absorbed by coming into contact with the sound absorbing portion arranged in the area. Accordingly, noise leaking to the outside from the gap formed around the sound insulating cover is reduced.

[0012] Then, the sound absorbing portion, the distal end surface of the open end portion of the shielding plate, if the outer peripheral surface of the outer peripheral surface or the portion covering the outer surface of the bent portion of the curved portion is formed to be circular arc surface, and diffraction Because the length of the surface where the coming sound contacts the sound absorbing part can be lengthened,
Noise energy is efficiently absorbed. In addition, if the length in the width direction of the outer peripheral surface of the sound absorbing portion is formed to be longer than half the wavelength of the frequency of the sound to be reduced, noise in a frequency region higher than the frequency to be reduced is set. Can also be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is an overall perspective view of a sound insulating cover according to the present embodiment, and FIG. 2 is a sectional view taken along line II-II of FIG.

The sound insulation cover of this embodiment is for preventing noise generated in the engine room of a truck from leaking, and includes a shield plate 1 made of an iron plate and a sound absorbing material 2 provided on the shield plate 1. It is configured. The shielding plate 1 has a thickness of 1.6
a base plate 1a formed by bending an iron plate of 1 mm in diameter and having a rectangular shape having a predetermined dimension;
and a mounting portion 1b which is formed to be bent so as to protrude substantially at a right angle from the upper end portion toward the outer surface side. Base 1a
A curved portion 1c which is curved in an arc shape toward the inner surface side is formed at three open ends excluding the upper end of. Also,
The mounting portion 1b is provided with a mounting hole 1d for screwing to the vehicle body frame.

The sound absorbing material 2 is formed in a substantially columnar shape including a layered main body 2a disposed on the inner surface of the base 1a of the shielding plate 1 so as to cover the entire surface and a curved portion 1c of the base 1a. And a sound absorbing portion 2b disposed along three open ends excluding the upper end of the base portion 1a. The main body 2a is formed to a thickness of about 20 mm. The sound absorbing portion 2b has a diameter portion having a thickness of about 40 mm and a circular arc surface forming an outer peripheral surface of the sound absorbing portion 2b having a circumferential length of about 12 mm.
0 mm or more is secured. As a result, a frequency of about 4
It is set so that noise of 00 Hz or more is effectively reduced by the sound absorbing unit 2b. The sound absorbing material 2 is made of a polyurethane foam formed by foaming polyurethane at a foaming ratio of about 10 times, and is integrally formed with the shielding plate 1 by integral molding.

The sound insulation cover of this embodiment constructed as described above is disposed as a side wall of an engine room of a truck such that the main body 2a of the sound absorbing material 2 faces the engine.
The mounting portion 1b of the shielding plate 1 has a mounting hole 1 on the lower surface of the vehicle body frame.
Attach by screwing through d. In this case, a predetermined gap required to avoid contact between the lower end of the sound insulation cover and the road surface is formed. In addition, both sides of the sound insulating cover are almost in contact with other members such as the vehicle body frame, but there are also parts where a gap is formed between the sound insulating cover and a mating member.

Thus, when the noise generated from the engine collides with the sound insulation cover, the noise is absorbed by the sound absorbing material 2 while being shielded by the shielding plate 1, thereby preventing the noise from leaking to the outside. . But,
Part of the noise leaks from a gap formed between the lower end of the sound insulating cover and the road surface and a gap formed between both ends of the sound insulating cover and a mating member. At this time, the noise diffracted by passing near the open end of the sound insulating cover comes into contact with the sound absorbing portion 2b covering the open end of the shielding plate 1, and the noise energy is absorbed. Accordingly, noise leaking to the outside from the gap formed around the sound insulating cover is reduced.

Therefore, the sound insulating cover of the present embodiment has the sound absorbing portion 2b formed at the open end of the shielding plate 1 wider than the thickness of the outer peripheral surface of the curved portion 1c, so that it is formed around the sound insulating cover. Noise that is diffracted from the gap and leaked to the outside can be effectively attenuated, so that noise outside the vehicle can be further reduced. In addition, the sound absorbing portion 2b of the present embodiment is formed in a substantially cylindrical shape including the curved portion 1c of the base portion 1a therein, and covers a portion covering the outer surface of the curved portion 1c (the end surface of the open end of the shielding plate 1). Since the outer peripheral surface is formed by an arcuate surface, the length of the surface where the diffracted noise contacts the sound absorbing portion 2b becomes longer, so that the noise energy can be efficiently absorbed.

Further, since the length in the width direction of the outer peripheral surface of the sound absorbing portion 2b is formed to be longer than a half wavelength of the frequency of the sound to be reduced, The noise in the frequency range higher than the current frequency can also be reduced. And the sound insulation cover of this embodiment is
Since the curved portion 1c is formed at the open end of the shielding plate 1 and the sound absorbing portion 2b is provided in the curved portion 1c, the sound absorbing portion 2b is provided.
Can be mounted in a good condition.

The sound-absorbing material 2 in this embodiment is composed of the main body 2
a and the sound absorbing portion 2b, as shown in FIG. 3, even when the sound absorbing material 2 is constituted only by the sound absorbing portion 2b provided at the three open ends of the base 1a of the shielding plate 1. Similarly to the above, it is possible to effectively reduce the noise leaking to the outside from the gap formed around the sound insulating cover. In the sound insulating cover of this embodiment, the shape of the sound absorbing portion and the shape of the open end of the shielding plate on which the sound absorbing portion is arranged are shown in FIG.
Various modifications can be made as illustrated in FIG.

The sound-insulating cover shown in FIG. 4 remains flat without forming a curved portion at the open end of the base 11a of the shield plate 11, and has a substantially cylindrical shape so as to include the open end therein. The sound absorbing portion 12b is provided. The sound insulation cover shown in FIG.
A curved portion 11c, which is formed in an open end portion in an arc shape toward the inner surface side, is formed larger than in the case of the above-described embodiment, and the outer peripheral surface of the curved portion 11c (the shielding plate 11).
The sound absorbing portion 12b having an arc-shaped cross section is provided so as to cover the front end surface of the open end portion. The sound absorbing portion 12b is integrally formed with one side portion of the main body portion 12a of the sound absorbing material 12 extending on the inner peripheral surface of the curved portion 11c.

In the sound insulating cover shown in FIG. 6, a bent portion 11e is formed at the open end of the base 11a of the shielding plate 11 at a substantially right angle toward the inner surface, and the outer surface of the bent portion 11e (the shielding plate 11e). A sound absorbing portion 12b having a mountain-shaped cross section is provided so as to cover the open end portion (the end surface of the open end portion). In addition, also in the case of this sound absorbing part 12b, the bent part 11e
The body part 12a of the sound absorbing material 12 extending on the inner surface of the body and one side thereof are connected and integrally formed.

The sound insulation cover shown in FIG. 7 has a bent portion 11e bent at a substantially right angle toward the inner surface side at the open end of the base 11a of the shielding plate 11, and includes a substantially rectangular tube including the bent portion 11e. A sound absorbing portion 12b having a shape is provided. In the sound insulation cover shown in FIG. 8, a curved portion 11c curved in an arc shape toward the outer surface side is formed at the open end of the base 11a of the shield plate 11, and the outer peripheral surface of the curved portion 11c (the open end of the shield plate 11). The sound absorbing portion 12b having an arc-shaped cross section is provided so as to cover the front end surface of the portion. In addition, the sound absorbing portion 12 b is provided on the base 11 of the shielding plate 11.
The sound absorbing member 12 is provided integrally on the inner surface of the main body 12a and is integrally connected to the main body 12a.

(Test) In order to confirm the effectiveness of the sound insulating cover according to the present invention, the sound intensity and the sound power level were measured, and a test was performed to compare with the conventional one. (1) Comparison of sound intensity The sound insulation cover (invention) of the present invention has a thickness of 1.6 m.
m, a shielding plate made of an iron plate having a length of 300 mm and a width of 300 mm, and a sound absorbing material made of polyurethane foam having a body portion having a thickness of 20 mm and a sound absorbing portion formed in a substantially cylindrical shape having a diameter of 60 mm were prepared. . As a conventional sound insulation cover (conventional product), a cover different from the invention product only in that there is no sound absorbing portion was prepared.

FIG. 9 shows a measurement method of this test. In a semi-anechoic chamber, an opening is formed on one side by combining an iron block C capable of sufficiently insulating sound from the outside on a concrete floor B. A cubic acoustic room D is formed, and a speaker F that generates random noise up to 15 kHz is installed at a predetermined position above the acoustic room D. And
A gap S between the opening of the acoustic room D and the concrete floor B
The sound insulation cover G to be tested is attached so that the sound is formed, and the sound leaking from the gap S is transmitted to the concrete floor surface B.
The sound incity is measured in the X direction on the measurement surface H perpendicular to the sound insulation cover. This measurement surface H is 350 m long.
m, 800 mm wide, and a total of 104 measurement points are set at intervals of 50 mm vertically and horizontally. The sound intensity refers to the ratio of the energy flow per unit area at a certain point (W / m ² ), and the numerical value is expressed in dB.

According to the above-mentioned method, the invention product and the conventional product are obtained at a 1/3 octave band frequency of 250 to 50.
The sound intensity in the region of 00 Hz was measured on the measurement surface H, and the results are shown in FIGS. FIG. 10 is a sound intensity map in the case of the invention, and FIG.
Is a sound intensity map for a conventional product. The numerical value in the sound intensity map indicates the intensity level at each measurement point. After the numerical value, P indicates that the sound energy is flowing in the same direction as the measurement direction.
(POSITIVE) or N (NEGAT
IVE). The lines in the sound intensity map are lines connecting the same intensity level values, and the step between the lines is 1 dB.

As is clear from the comparison between FIG. 10 and FIG. 11, in the case of the invention, the sound coming out of the acoustic chamber D from the gap S through the vicinity of the sound absorbing portion is smaller than that of the conventional product. It can be seen that, at the same time, the intensity level in the vicinity of the sound absorbing part is significantly reduced. Therefore, it has been proved that the noise leaking from the gap S can be effectively reduced by having the sound absorbing portion as in the invention.

(2) Comparison of sound power level In this test, in addition to the invention product and the conventional product used in the above test, an invention product which differs from the invention product only in that the diameter of the sound absorbing portion is 40 mm as a comparative example And the diameter of the sound absorbing part is 2
An invention product different from the invention product only at the point of 0 mm was prepared. Then, a sound insulation cover to be tested is attached to the opening of the acoustic chamber D of the test apparatus, and the measurement direction (X direction in FIG. 9) is measured on the sound intensity measurement surface H.
1/30 CT frequency 2
The measurement was performed in the range of 50 to 5000 Hz. Table 1 shows the measurement results. In addition, the difference of the sound power level reduction amount of the invention product, the invention product and the invention product from the conventional product is calculated,
This is shown in the graph of FIG.

The sound power Lw is P: a certain sound power, P ₀ : a reference sound power (1 pW (10 pW
^-12 W)), it is obtained by the following equation. Lw = 10 log (P / P ₀ )

[0030]

[Table 1] As is clear from Table 1 and FIG. 12, in the case of the invention, the invention, and the invention, the sound power is lower than that of the conventional product at each of the frequencies. In addition, when comparing the invention, the invention, and the invention, the larger the diameter of the sound absorbing portion, that is, the longer the circumferential length of the outer peripheral surface of the sound absorbing portion, the larger the amount of reduction in the acoustic power. You can see that. Further, it can be seen that by increasing the length of the outer peripheral surface of the sound absorbing portion in the circumferential direction, an effective effect of reducing the acoustic power from a low frequency can be obtained. Therefore, it is possible to obtain an effective reduction effect from a low frequency by tuning the thickness and size of the sound absorbing portion according to the target reduction frequency.

Embodiment 2 FIG. 13 is a sectional view showing a state in which the sound insulation cover according to the present embodiment is attached to a vehicle body as a body panel. The sound insulation cover according to the present embodiment is provided as a body panel below both sides of a carrier or a container installed on a body frame of a truck, and includes a shielding plate 21 made of resin and a shielding plate 21. The sound absorbing member 22 is provided.

The shielding plate 21 is formed of a resin plate having a thickness of about 5 mm, and has a base 21a extending in a strip shape in the lateral direction, and a mounting portion 21b formed by bending the upper end of the base 21a at a substantially right angle. Consists of The lower end of the base 21a is slightly curved inward, and a bent portion 21c that is bent inward at a substantially right angle is formed at the front end thereof. The mounting portion 21b has a mounting hole (not shown) for screwing to the vehicle body frame.

The sound absorbing material 22 is provided along a layered main body 22a disposed on the inner surface of the base 21a and the mounting portion 21b of the shielding plate 21 so as to cover the entire surface thereof, and along three ends excluding the upper end of the base 21a. Absorbing part 2 provided integrally with the main body part 22a
2b. The main body 22a is formed to a thickness of about 20 mm. And the sound absorbing portion 22b is
Is provided so as to cover the inner surface of the lower end portion and the outer surface of the bent portion 21c, and the outer peripheral surface thereof becomes an arc surface and bulges inward and downward so that the cross section becomes a mountain shape. The sound absorbing portion 22b bulges inward from the main body portion 22a and is formed to a thickness of about 50 mm. The length in the width direction of the arc surface forming the outer peripheral surface of the sound absorbing portion 22b is about 6
0 mm or more is ensured, and the noise having a frequency of 2800 Hz or more is set to be effectively reduced by the sound absorbing portion 22b. The sound absorbing material 22 is made of a polyurethane foam formed by foaming polyurethane at a foaming ratio of about 10 times, and is integrally formed with the shielding plate 21 by integral molding.

The sound insulation cover of this embodiment constructed as described above is disposed on the body frame of a truck, for example, below the both sides of a container 25 so that the sound absorbing material 22 faces inward. Of the container 25
It is attached by screwing it through the mounting hole to the lower surface of. In this case, a predetermined gap required to avoid contact between the two is formed between the lower end of the sound insulating cover and the road surface, and both sides of the sound insulating cover are open spaces.

Thus, when noise such as engine sound or reflected sound collides with the sound insulation cover, the noise is absorbed by the sound absorbing material 22 while being shielded by the shielding plate 21, so that the noise is leaked to the outside. To prevent. However, part of the noise leaks from a gap formed between the lower end of the sound insulating cover and the road surface and an open space formed on both ends of the sound insulating cover. At this time, the noise diffracted by passing near the open end of the sound insulating cover comes into contact with the sound absorbing portion 22b provided so as to cover the open end of the shielding plate 21, and the noise energy is absorbed. Accordingly, noise leaking to the outside from the gap formed around the sound insulating cover is reduced.

Therefore, the sound insulating cover of the present embodiment has the sound absorbing portion 22b formed at the open end of the shielding plate 21 wider than the thickness of the outer peripheral surface of the bent portion 21c, so that it is formed around the sound insulating cover. Noise that is diffracted from the gap and leaked to the outside can be effectively attenuated, so that noise outside the vehicle can be further reduced. Further, since the outer peripheral surface of the sound absorbing portion 22b of this embodiment is formed by an arc surface, the length of the surface where the diffracted noise contacts the sound absorbing portion 22b becomes longer, so that the noise energy can be efficiently reduced. Can be absorbed.

Further, since the length in the width direction of the outer peripheral surface of the sound absorbing portion 22b is formed to be longer than a half wavelength of the frequency of the sound to be reduced, The noise in the frequency range higher than the current frequency can also be reduced. In the sound insulating cover of the present embodiment, a bent portion 21c is formed at an open end of the shielding plate 21,
Since the sound absorbing portion 22b is provided in the bent portion 21c, the mounting state of the sound absorbing portion 22b can be improved.

In the sound insulation cover of this embodiment,
The shape of the sound absorbing portion 22b and the shape of the open end of the shielding plate 21 in which the sound absorbing portion 22b is arranged can be variously changed in the same manner as in the first embodiment. [Embodiment 3] FIG. 14 is a sectional view showing a state in which the sound insulating cover according to the present embodiment is attached to an engine.

The sound insulation cover of this embodiment is directly attached to an engine E mounted on a vehicle, and includes a shielding plate 31 made of an iron plate and a sound absorbing material 3 provided on the shielding plate 31.
And 2. The shielding plate 31 is formed in a rectangular shape having a predetermined dimension by an iron plate having a thickness of about 1.6 mm corresponding to the outer peripheral shape of a portion of the engine E to which the sound insulating cover is attached.

The sound absorbing material 32 is provided on the inner surface of the shield plate 31 so as to cover the entire surface thereof, and a layered main body portion 32a is provided along the four open ends of the shield plate 31 and the open ends thereof. And a sound absorbing portion 32b formed in a substantially cylindrical shape. The main body 32a is formed to a thickness of about 10 mm. The sound absorbing portion 32b has a diameter portion having a thickness of about 30 mm and a circumferential length of an arc surface forming the outer peripheral surface of the sound absorbing portion 32b of 50 mm or more. Thereby, the noise having a frequency of about 3400 Hz or more is set to be effectively reduced by the sound absorbing portion 32b. The sound absorbing material 32 is made of polyurethane foam formed by foaming polyurethane at a foaming ratio of about 10 times, and is formed integrally with the shielding plate 31 by integral molding.

The sound insulating cover is attached to a predetermined position of the engine E by a mounting bracket 33 such that the sound absorbing material 32 faces the engine block with a little space therebetween. In this case, a gap is formed between the sound insulating cover and other members at the peripheral end. Accordingly, when the noise generated from the engine E collides with the sound insulation cover, the noise is absorbed by the sound absorbing material 32 while being shielded by the shielding plate 31, thereby reducing the noise leaking to the outside of the sound insulation cover. At this time, the noise diffracted by passing near the open end of the sound insulating cover comes into contact with the sound absorbing portion 32b covering the open end of the shielding plate 31 and the noise energy is absorbed, so that the noise from the periphery of the sound insulating cover is absorbed. Noise leaking to the outside is reduced.

Accordingly, the sound insulating cover of this embodiment has the sound absorbing portion 32b formed at the open end of the shielding plate 31 wider than the thickness of the front end surface thereof, so that the gap formed around the sound insulating cover is formed. The noise that is diffracted from and leaks to the outside can be effectively attenuated, whereby the noise outside the vehicle can be further reduced. Further, since the outer peripheral surface of the sound absorbing portion 32b of this embodiment is formed by an arc surface, the length of the surface where the diffracted noise contacts the sound absorbing portion 32b becomes longer, so that the noise energy can be efficiently reduced. Can be absorbed.

Since the length in the width direction of the outer peripheral surface of the sound absorbing portion 32b is formed so as to be longer than the length of a half wavelength of the frequency of the sound to be reduced, It is also possible to reduce noise in a frequency range higher than a certain frequency. In the sound insulating cover of the present embodiment, the shape of the sound absorbing portion 32b and the shape of the open end of the shielding plate 31 on which the sound absorbing portion 32b is arranged can be variously changed as in the case of the first embodiment. it can.

[Embodiment 4] FIG. 15 is a sectional view of a sound insulating cover according to this embodiment. The sound insulation cover of this embodiment is used as a rear bumper of a vehicle, and includes a shielding plate (bumper body) 41 made of resin and a sound absorbing material 42 provided on the shielding plate 41.

The shielding plate 41 is formed in a laterally long shape corresponding to the outer peripheral shape of the rear body of the vehicle, and is bent at substantially right and left upper and lower ends to have a substantially U-shaped cross section.
The sound absorbing material 42 includes a layered main body 42 a disposed to cover the entire inner surface of the lower bent portion of the shielding plate 41, and a shielding plate 4.
A sound absorbing portion 42 disposed along the open end of the lower bent portion 1 and having a substantially cylindrical shape including the open end therein.
b. The main body 42a is formed to a thickness of about 20 mm. The sound absorbing portion 42b has a diameter portion having a thickness of about 60 mm.
The circumferential length of the arc surface that forms the outer peripheral surface of is 120 mm
The above is secured. Thereby, the frequency is 1400H
It is set so that noise of z or more is effectively reduced by the sound absorbing portion 42b. The sound absorbing material 42 is made of polyurethane foam formed by foaming polyurethane at a foaming ratio of about 10 times, and is formed integrally with the shielding plate 41 by integral molding.

The sound insulation cover is fixedly held and fixed to the rear body of the vehicle by a screw at a predetermined position on the rear side thereof, and is provided as a part of a partition wall of the body together with a shock absorber as a bumper. In this case, a slight gap is formed between the sound absorbing portion 52b of the sound insulating cover and the body. Accordingly, noise such as engine sound, exhaust sound, and their reflected sounds that come to the rear from the abdomen of the vehicle when the vehicle is running or the like are shielded by the shielding plate 41, and the noise energy is reduced by the sound absorbing material 42. By being absorbed,
Leakage of the sound insulation cover to the outside is reduced. At this time, the noise diffracted by passing near the lower end of the sound insulating cover comes into contact with the sound absorbing portion 42b covering the open end of the shielding plate 41 and the noise energy is absorbed, so that the sound absorbing portion 42b and the body are The noise leaking from the gap to the outside is further reduced.

Therefore, since the sound insulating cover of this embodiment has the sound absorbing portion 42b formed at the open end of the shielding plate 41 wider than the thickness of the front end surface thereof, the gap formed around the sound insulating cover is formed. The noise that is diffracted from and leaks to the outside can be effectively attenuated, whereby the noise outside the vehicle can be further reduced. Further, since the outer peripheral surface of the sound absorbing portion 42b of this embodiment is formed by an arc surface, the length of the surface where the diffracted noise contacts the sound absorbing portion 42b becomes longer, so that the noise energy can be efficiently reduced. Can be absorbed.

Further, since the length in the width direction of the outer peripheral surface of the sound absorbing portion 42b is formed to be longer than a half wavelength of the frequency of the sound to be reduced, It is also possible to reduce noise in a frequency range higher than a certain frequency. In the sound insulating cover of the present embodiment, the shape of the sound absorbing portion 42b and the shape of the open end of the shielding plate 41 on which the sound absorbing portion 42b is arranged can be variously changed as in the case of the first embodiment. it can.

[0049]

According to the sound-insulating cover of the present invention, the sound-insulating cover comprises: a shielding plate mounted on a vehicle body for shielding noise generated from equipment mounted on the vehicle; and a sound absorbing material provided on the shielding plate. The sound absorbing material covers at least the distal end surface of the open end of the shielding plate, the outer peripheral surface of the curved portion or the outer surface of the bent portion, and
Since the end surface, the outer peripheral surface or the sound absorbing portion formed to be wider than the thickness width of the outer surface , it is possible to effectively attenuate noise leaking to the outside by diffracting from a gap formed around the sound insulating cover. As a result, outside noise can be further reduced.

[0050] Then, the sound absorbing portion, the distal end surface of the open end portion of the shielding plate, if the outer peripheral surface of the outer peripheral surface or the portion covering the outer surface of the bent portion of the curved portion is formed to be circular arc surface, and diffraction Because the length of the surface where the coming sound contacts the sound absorbing part can be lengthened,
Noise energy can be efficiently absorbed. Also,
If the length in the width direction of the outer peripheral surface of the sound absorbing portion is formed to be longer than a half wavelength of the frequency of the sound to be reduced, noise in a frequency region higher than the frequency to be reduced is reduced. can do.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a sound insulating cover according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view of a sound insulation cover according to a modification of the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a sound insulating cover according to another modification of the first embodiment of the present invention.

FIG. 5 is a sectional view of a sound insulation cover according to another modification of the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of a sound insulation cover according to another modification of the first embodiment of the present invention.

FIG. 7 is a cross-sectional view of a sound insulating cover according to another modification of the first embodiment of the present invention.

FIG. 8 is a cross-sectional view of a sound insulation cover according to another modification of the first embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a method of measuring sound intensity in a test.

FIG. 10 is a sound intensity map in the case of the invention product in the sound intensity measurement test.

FIG. 11 is a sound intensity map for a conventional product in a sound intensity measurement test.

FIG. 12 is a graph showing the difference in the amount of sound power reduction between the invention, the invention, and the conventional product in the sound power measurement test.

FIG. 13 is a cross-sectional view showing a state where the sound insulation cover according to the second embodiment of the present invention is attached to a vehicle body as a body panel.

FIG. 14 is a cross-sectional view showing a state where the sound insulation cover according to the third embodiment of the present invention is attached to an engine block.

FIG. 15 is a sectional view of a sound insulating cover according to Embodiment 4 of the present invention.

FIG. 16 is a side view of the truck showing an arrangement position of the sound insulation cover.

FIG. 17 is an explanatory diagram showing a state in which noise leaks from a gap at the lower end of the sound insulation cover.

FIG. 18 is a chart used for diffraction calculation when designing a sound insulating cover.

19A is a table for calculating a constant K value when calculating a noise attenuation amount of a thick sound insulating cover, and FIG. 19B is an explanatory diagram illustrating an angle when calculating the constant K value. .

[Explanation of symbols]

1, 11, 21, 31, 41, 71: Shielding plate 1a, 11a, 21a: Base 1b, 21b: Mounting portion 1c, 11c: Curved portion 1d: Mounting hole 11e, 2
1c Bending portion 2, 12, 22, 32, 42, 72 Sound absorbing material 2a, 22a, 32a, 42a Body portion 2b, 12b, 22b, 32b, 42b Sound absorbing portion 2
5 ... Container 33 ... Mounting bracket 7 ... Sound insulation cover 70 ... Body frame A ... Road surface B ... Concrete floor surface C ... Iron block D ... Gap E ... Engine F ... Speaker G ... Sound insulation cover
S: gap H: measuring surface

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60R 13/08 G10K 11/16

Claims (5)

(57) [Claims] 1. A shielding plate mounted on a vehicle body for shielding noise generated from equipment mounted on the vehicle, and a sound absorbing material provided on at least a planar open end of the shielding plate. Material the vehicle sound insulation cover comprises said at least a tip surface has covered, and sound absorbers which are wider than the thickness width of the front end surface of the open end portion of the shield plate. 2. An open end having a curved portion curved in an arc shape.
Generated from equipment mounted on the vehicle
Shielding plate, Sound absorbing material provided on at least the curved portion of the shielding plate
And, The sound absorbing material covers at least the outer peripheral surface of the curved portion,
It has a sound absorbing part formed wider than the thickness of the outer peripheral surface.
A sound insulation cover for vehicles. 3. An open end having a bent portion, which is attached to a vehicle body.
Shields noise generated from equipment mounted on vehicles
A shielding plate, Sound absorbing material provided at least at the bent portion of the shielding plate
And, The sound absorbing material covers at least an outer surface of the bent portion, and
It has a sound absorbing part formed wider than the thickness of the outer surface
A sound insulation cover for a vehicle, characterized in that: Wherein said sound-absorbing part, the tip of the open end
The sound insulating cover for a vehicle according to any one of claims 1 to 3 , wherein a surface, the outer peripheral surface, or an outer peripheral surface of a portion covering the outer surface is formed by an arc surface. 5. The length in the width direction of the outer peripheral surface of the sound absorbing portion, the vehicle of claim 1, wherein is formed longer than the length of a half wavelength of the frequency of the sound for the purpose of reducing Sound insulation cover.