JP2002104101A - Internal sound absorbing body in automobile engine room - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution which is light, high in sound absorbing effect and capable of being laid in a simple and easy way as an internal sound absorbing body in an automobile engine room. SOLUTION: This sound absorbing body 10 is laid in the engine room of an automobile to reduce an engine noise, forms a flexible porous material 20 like an elongated cylinder having a hollow part 21 inside, and covers a long material such as a wire, a rib or the like in the engine room to be laid. The sound absorbing body (inside hollow part) is temporarily opened at a cut 11 by utilizing the flexibility of the sound absorbing body, the wire W as a lying object for the sound absorbing body is contained in the hollow part 21 of the sound absorbing body through the cut, and again the sound absorbing body is returned to its initial shape. Thus, the sound absorbing body wraps the wire W, and the sound absorbing body can be laid simply without any special engagement tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorber in an engine room of an automobile and a method of laying the same.

[0002]

2. Description of the Related Art An internal combustion engine such as a gasoline engine is used as a drive source of an automobile, and is installed at a front part and a rear part of the automobile with a space therebetween. The engine burns gasoline or the like as fuel, converts the obtained energy into driving force, transmits the energy to wheels, and drives the vehicle. A considerable amount of noise is generated as the engine is driven (combustion, exhaust). Conventionally, in order to prevent a large amount of this noise from leaking out of the vehicle, a sound absorber is laid in an engine room to absorb engine noise. Conventional sound absorbers are generally laid along the inner surface of a vehicle hood panel by hot pressing a plate material made of glass wool impregnated with a thermosetting resin to form a flat panel. . Glass wool has excellent heat resistance and is not easily degraded even at high temperatures in the engine room, and by accumulating fine fibers,
The effect of taking sound waves inside and attenuating them is excellent.

[0003] Conventional sound absorbers in an engine room formed of glass wool have the following problems. Because of its high density and heavy weight, it has been difficult to use it for small vehicles. High temperature molding (hot pressing) of glass wool was required. Work required for installation (clamping to the hood panel)
However, laying was troublesome and time-consuming. There is a tendency to reflect sound waves incident from a direction greatly inclined from the vertical direction of the sound absorber, and the sound absorbers cannot absorb sound waves from all directions. Because of difficulty in controlling the ventilation resistance, there were cases where sound waves in a wide frequency range could not be absorbed or sound waves in a target frequency range could not be absorbed.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a light-weight structure having a high sound-absorbing effect as a sound-absorbing body in an engine room of an automobile, and a structure which can be easily laid.

[0005]

Means for Solving the Problems An object of the present invention is to provide a sound absorber which is laid in an engine room of an automobile to reduce engine noise, wherein a flexible porous material is hollow inside. It is formed into a long cylindrical shape with a part, and covers long objects such as wires (accelerator wires, electrical wiring, liquid supply pipes) and ribs (seam of panels, irregularities, etc.) in the engine room. According to a sound absorber in an engine room of a car, which is characterized by being laid.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, in which a wire W is provided in an engine room of an automobile.
Perspective view of a state in which the sound absorbing body is laid in a form to cover
And a sectional view taken along line AA.

The sound absorber 10 is made of a flexible porous material 20 and is formed in a long cylindrical shape having a hollow portion 21 inside. The outer diameter of the cylinder is 30 to 200 mm, and the inner diameter (hollow part diameter) is about 10 to 100 mm. As the porous material, fiber felt, resin foam, glass wool, rock wool, or a material obtained by impregnating these materials with a binder is used.The porous material bends when subjected to a load, and returns to its original shape when the load is removed. Flexibility (elasticity) to restore to the shape of

A skin material 30 is laminated on the outer surface of the cylinder of the flexible porous material. The most suitable skin material is a breathable nonwoven fabric, and a melt blown nonwoven fabric or a spunbonded nonwoven fabric can be used. The preferred area weight is 5
It is about 0 g / m ² . The skin material functions to protect the flexible porous material and also functions to control the air permeability of the sound absorber.

It is preferable that the flexible porous material and the skin material constituting the sound absorber have air permeability, and the total airflow resistance from the outer surface side of the sound absorber to the hollow portion inside the sound absorber is 100 Nsm ^{−. When} it is in the range of ^{3 to} 2500 Nsm- ^3, the sound absorbing performance is optimized.

For the installation of the sound absorber, a continuous cut 11 extending from the outer surface 22 to the hollow portion 21 is formed along the longitudinal direction of the sound absorber. Cut 11 using flexibility of sound absorber
By temporarily opening the sound absorbing body (inside hollow portion) from above, the wire W to be laid on the sound absorbing body is stored in the hollow portion 21 of the sound absorbing body through the opened cut, and the sound absorbing body is returned to the original shape again. The sound absorber wraps around the wire, and the sound absorber can be laid with one touch without using a special engagement tool. (In some cases, a magic fastener may be wound from the outside of the sound absorber, or a double-sided tape may be applied to the inside.) The cuts are formed in a straight line as shown in the figure, as well as curved, zigzag, spiral, etc. Can also be formed.

FIG. 2 shows a second embodiment of the present invention, and is a cross-sectional view showing a state in which a sound absorbing body is laid so as to cover a long rib in an engine room of an automobile. The same sound absorbing body 40 (the skin material 42 is laminated on the outer surface of the flexible porous material 41 on the cylindrical surface) of the same sound absorbing body 40 as that of the first embodiment is attached to the narrow rib R erected from the body panel P of the engine room. Lay it.
The laying mode of the sound absorber in this embodiment is similar to that of the first embodiment, in that the cut 43 is temporarily widened using the flexibility of the sound absorber, and the rib R to be laid on the sound absorber is sandwiched between the cuts. By returning the sound absorber to its original shape again.

[0012]

(Example 1) (Sound absorber) A flexible porous material obtained by impregnating a phenol resin as a binder into rock wool is used, and has a density of 0.09 g / cm ³ and a hollow portion inside. It is formed into a long cylindrical shape (outer diameter 75 mm, inner diameter 35 mm). On the outer surface side of the cylinder, a nonwoven fabric made of polyester fiber (surface weight: 40 g / m ² ) is laminated as a skin material. The total airflow resistance from the outer surface of the sound absorber to the hollow portion of the sound absorber is 300.
Nsm- ³ . (Layout mode) Accel wire, cooling water hose, etc. in the engine room of the test vehicle (sedan type vehicle with an engine room in front of the vehicle, engine displacement: 3000 cc)
The portion of the panel reinforcement mainly located above the engine body is the object to be laid, and the sound absorber is opened in a manner in which a cut formed along the longitudinal direction of the sound absorber is opened and the object to be laid is sandwiched inside. Laid. The total installed amount of the sound absorber is 1 m in total.

(Evaluation method) A test vehicle having a sound absorbing body laid in the engine room in the above-described manner was driven in an anechoic chamber in a no-load state with a gear in a neutral range. The noise levels inside and at the driver's seat (D seat) ear position were measured. In addition, the noise level in the engine room without the sound absorber installed and the noise level at the driver's seat (D seat) ear position were measured in the same manner as a comparative example.

(Evaluation Results) FIG. 3 shows the evaluation results of the noise level. As shown in the figure, the embodiment (shown by a dotted line) reduces the noise level in the engine room in the range of 315 to 10 kHz compared to the comparative example (shown by a solid line).
dB improvement. Further, the noise level at the driver's seat (D seat) ear position is improved by 2 to 4 dB. Since the sound absorber of the invention is laid at an intermediate position in the space of the engine room,
Compared to conventional sound absorbers laid along food panels,
It is considered that a large air layer can be formed behind the sound absorber, so that the sound absorption effect can be enhanced from low frequencies to high frequencies. In addition, since the cross section is circular as a whole, it is considered that sound waves incident from all directions were absorbed with high efficiency.

[0015]

The sound-absorbing body of the present invention has a lightweight and excellent sound-absorbing structure, and can be easily laid on a wire or a rib in an engine room of an automobile.

[Brief description of the drawings]

FIG. 1 is a perspective view and a cross-sectional view showing a first embodiment of the invention.

FIG. 2 is a perspective view showing a second embodiment of the present invention.

FIG. 3 shows the measurement results of sound absorbing properties.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sound absorber 11 Notch 20 Flexible porous material 21 Hollow part 22 Outer surface 30 Skin material W Wire R Rib

Claims (5)

[Claims] 1. A sound absorber laid in an engine room of an automobile to reduce engine noise, wherein a flexible porous material is formed in a long cylindrical shape having a hollow portion inside.
A sound absorber in an engine room of an automobile characterized by being laid and covered with a long object such as a wire or a rib in an engine room. 2. The sound absorber in an engine room of an automobile according to claim 1, wherein a skin material is laminated on at least the outer surface of the cylinder of the flexible porous material. 3. The sound absorber in an engine room of an automobile according to claim 2, wherein the skin material is a non-woven fabric. 4. The total airflow resistance from the outer surface of the sound absorber to the hollow inside the sound absorber is 100 Nsm ⁻³ to 250 Nsm.
4. The sound absorber in an engine room of an automobile according to claim 1, wherein the sound absorber is in a range of 0 Nsm- ³ . 5. A sound absorber in an engine room of an automobile according to claim 1, wherein a continuous cut is formed from an outer surface side to a hollow portion along a longitudinal direction of the sound absorber. .