KR20050116670A - Acoustic absorber of automobile - Google Patents

Abstract

The present invention is a vehicle sound absorbing material consisting of three layers of sound absorbing materials having different apparent densities composed of low melting point fibers (LMF) and high melting point fibers (SF), wherein the sound absorbing material for automobiles is 40 ~ 40% of the area of the low density sound absorbing material, the low density sound absorbing material It is a three-layer structure consisting of a high-density sound absorbing material arranged at 100% and a non-breathable layer made of rubber or resin material disposed at 10 to 90% of the area of the high-density sound absorbing material, and is disposed so that one surface of the low density sound absorbing material is in contact with the noise generating area. The present invention relates to a sound absorbing material for automobiles, wherein the relatively high density sound absorbing material is intensively disposed in a region having a high noise improvement contribution, and a non-breathable layer made of rubber or the like is further disposed on the surface of the high density sound absorbing material in a low frequency region. It is possible to obtain an effect of improving sound absorbing and insulating performance.

Description

Acoustic absorber of automobile

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sound absorbing materials for automobiles, and more specifically, after mixing low melting point fiber binders (hereinafter referred to as LMF) and high melting point fibers (hereinafter referred to as SF) such as polyester or polyolefin in a predetermined fineness ratio and weight ratio Manufactured through needle punching and general plush process to have different densities, using heat or adhesive to laminate the relatively dense layer at the main noise generating area, and at the same time, non-breathability such as rubber on the surface of the high-density sound absorbing material The present invention relates to a sound absorbing material for automobiles, which further includes layers to improve sound absorbing and insulating performance in the low frequency region.

In general, typical noises introduced into the interior of a vehicle include engine permeation noise generated by an engine and transmitted through a vehicle body or air, and friction noise between wheels and the ground. The engine cover or hood insulator is used to suppress such noise, but the effect of removing the noise is insignificant, and the dash outer attached to the outside of the vehicle and the dash inner attached to the interior of the vehicle, Floor carpets, etc., are responsible for removing most of the noise.

Therefore, in these cases, in order to block the noise flowing into the sound absorbing material in most cases, the sound absorbing and insulating material (hereinafter referred to as sound absorbing material) in which polyurethane foam is separately attached to the sound insulating material layer called heavy layer has been used. In this case, however, the sound insulation performance is excellent, but the assembly (weight) of the assembly (heavy) is usually 6 ~ 9kg / heavier, there is a problem that there is little sound absorption performance against the noise generated in the room. In addition, a method of attaching a separate heavy layer sound insulation material to a vehicle interior to a triple structure sound absorbing material in which a low density material is attached to both surfaces of a high density material is disclosed in Japanese Patent Laid-Open No. 10-236238. The sound absorption effect was insufficient.

As another method, a method is used in which a predetermined binder fiber is added after crushing the dead sand to manufacture a product. In this case, due to the difficult management of our company, the sound absorption is severely deteriorated, and workability deterioration due to dust generation during processing, investment cost burden due to installation of dust collector, etc., and problems such as odor when it is used inside the vehicle for a long time. In addition, in recent years, a method of using a non-woven fabric layer which is heat-bonded with a binder fiber, such as polyolefin and polyester, having a relatively low melting point and a synthetic fiber having a high melting point, has a low density instead of a heavy sound insulation material layer, Many methods have been proposed to reduce the weight of parts by constructing two or more layers with different aeration rates. (Japanese Patent Application Laid-Open No. 8-152890, Japanese Patent Application Laid-Open No. 11-180224, Japanese Patent Application Laid-Open No. 6-247202, Japan 6-259080, Japanese Patent Application Laid-Open No. 8-108500, Japanese Patent Application Laid-Open No. 10-247085, and Korean Laid-Open Patent Publication No. 2003-0000746, etc.) However, these methods simply reduce the weight of parts by arranging the nonwoven fabric in a plurality of layers. Compared to the method of attaching the layer can be achieved in part, there was a limit to reduce to the same level as the present invention.

In more detail, in general, in the case of a sound absorbing material composed of a sound absorbing material and a fiber material attached with a heavy layer sound insulating material, a mechanism for transferring sound from the engine to the interior of the vehicle is different. In other words, in the case of the sound absorbing and insulating material specification with the heavy layer sound insulating material, the noise generated from the engine passes through the dash panel of the vehicle body first, and the passed noise is applied to the crash pad inside the vehicle. It is reflected back to the sound insulation material. The reflected sound is finally introduced into the vehicle. When frequency analysis is performed on the introduced noise, most of the rough and loud high frequency sound is more than 1000 Hz. However, in the case of the dual-layer sound absorbing material composed only of fiber material, the noise generated by the engine is primarily reflected through the crash panel of the vehicle body and reflected to the crash pad, which is transmitted to the sound absorbing material part. In this case, most of the high-frequency sound of more than 1000Hz is absorbed, so the noise flowing into the vehicle is changed to a soft sound that is easy to hear, and the sound quality is improved.

In addition, when analyzing the sound pressure distribution generated when the noise emitted from the engine comes into contact with the dash panel, the sound center is the largest and the sound pressure drops toward the outside. In other words, the noise improvement contribution of the sound absorbing material in the dasher is the largest part of the dash panel adjacent to the engine and the contribution decreases as the distance goes away. In this case, the structure of the sound absorbing material is applied equally to the corresponding part. no need. However, at present, the sound absorbing material having the same structure is attached to the entire site, and thus, satisfactory weight reduction is difficult in this case, and many problems occur in terms of workability. That is, in the case of the sound absorbing material composed of the same area with the high density layer and the low density layer, the surface strength becomes too hard during and after molding, so that it is difficult to form the sound absorbing material in the angular form for application to the bent portion of the vehicle body. Problems such as poor fitability, such as removal of the product during installation, are frequently encountered.

In addition, in the case of the existing sound absorbing material, the interior noise was improved by shielding the transmission noise of the engine and the like by using the material of the same structure on part or the whole of the noise part (Japanese Patent Laid-Open No. 11-115645, etc.). Or later, the surface of the product is hardened, the formability of the angular form is inferior, and the problem is removed when attached to the fixing pin at the end of the body panel.

Apart from this problem, especially in the case of a vehicle equipped with a diesel engine, considerable low frequency noise is introduced into the room from the engine part, and the sound absorbing material alone lacks a noise reduction effect, especially in the noise reduction range of 600 Hz or less. There was a problem.

The present invention significantly reduces the weight, which is a problem of conventional products, improves room noise by preventing sound absorption and improves workability such as formability and mounting property, and at the same time reduces noise due to low frequency in the range of 600 Hz or less. It was. Therefore, in the present invention, by selectively disposing a high density sound absorbing material to the part where the engine of the dash panel directly receiving the noise generated by the engine and a fan, a belt part, etc., and at the same time, a low density sound absorbing material is disposed throughout the noise area, thereby generating indoors. In addition, by effectively removing the noise introduced into the room, by placing a non-breathable layer such as rubber and resin on the surface of the high-density sound absorbing material, while reducing the weight of the existing sound absorbing material while maintaining the effect of improving indoor noise, which is the original purpose of the sound absorbing material, In addition, it improves workability such as formability and mounting performance. Also, in the noise of engine transmission, it removes high frequency noise of 1000Hz or more, especially 1000 ~ 4000Hz, among the noise introduced into the room, Indoors by blocking the inflow of low-frequency noise in the 300-600 Hz range It was able to invent the sound-absorbing material for automobiles that can improve the sound.

Therefore, in the present invention, in the automotive sound absorbing material composed of three layers of sound absorbing materials having different apparent densities composed of low melting point fibers (LMF) and high melting point fibers (SF),

The vehicle sound absorbing material is a three-layer layer consisting of a low density sound absorbing material, a high density sound absorbing material disposed at 40 to 100% of the area of the low density sound absorbing material, and a non-breathable layer made of rubber or resin material disposed at 10 to 90% of the area of the high density sound absorbing material. It is a structure, there is provided a sound absorbing material for automobiles, characterized in that one surface of the low density sound absorbing material is disposed in contact with the noise generating portion.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In the present invention, unlike the sound-absorbing material such as polyester, which has been composed of a conventional single layer, it is possible to provide a sound absorbing material for automobiles by combining a sound absorbing material of two or more stages by heat treatment or a separate bonding process by forming a multi-structure having a different apparent density.

The sound absorbing material for automobiles of the present invention is composed of two stages of sound absorbing materials having different apparent densities of low melting point fibers (LMF) and high melting point fibers (SF), as shown in FIG. A sound absorbing material having a weight of / m 2 is used, and in the case of the high density sound absorbing material (2), it is usually composed of a weight of a surface density of 500 g / m 2 to 2000 g / m 2, and the non-breathable layer 3 is composed of a known rubber or resin material. In the case of the surface density (weight) of the low density and high density sound absorbing material, the range is similar, but the apparent density is different because the thickness of each sound absorbing material is different.

For example, if the low-density sound absorbing material uses a thickness of 15mm, 1200g / ㎡, and the high-density sound absorbing material uses a thickness of 5mm, 800g / ㎡ can be provided two kinds of sound absorbing material different in apparent density.

In the present invention, it is preferable that the application area of the high-density sound absorbing material in the molding process is configured to be about 30 to 100%, more preferably 50% or more of the low-density sound absorbing material. And the application area of the non-breathable layer is preferably configured to be 10 to 90%, more preferably 20% or more of the area of the high-density sound absorbing material.

In addition, in the present invention, the low-density sound absorbing material (1) is installed in contact with the noise generating parts such as the dash, bottom, ceiling, etc., the high-density sound absorbing material (2) and the non-breathable layer (3) indoors so that the noise improvement effect is large It is preferable to arrange to face negatively.

When the composition is configured as described above, the weight of the high-density sound absorbing material is about 800 g / m 2, and about 240 to 800 g / m 2 is used as compared with the existing sound absorbing material, and the non-breathable layer is 200 to about 2000 g / m 2. By using about 1800g / ㎡, it is possible to obtain a weight reduction effect of about 50% based on the total weight of the sound absorbing material, so that the sound absorbing and insulating performance, which is the original purpose of the sound absorbing material, can be sufficiently exhibited, while also improving the fuel efficiency of the vehicle. .

At this time, when the high-density sound absorbing material is disposed less than 30% of the area of the low-density sound absorbing material, the original sound absorbing and insulating performance, in particular, the sound insulating performance is remarkably lowered, which is unsuitable. In this case, it is preferable to arrange and adjust the area appropriately in terms of improving moldability and wearability of the angular portion. In addition, when the non-breathable layer is disposed at less than 10% of the area of the high-density sound absorbing material, the improvement of the low frequency sound absorbing and insulating performance of the original purpose of less than 600 Hz, in particular, the sound insulation performance is insignificant. Although not in, it was not suitable in terms of weight reduction effect and moldability and mountability.

The sound absorbing material for automobiles of the present invention is a needle punching and mixing so that the apparent density is different after mixing a low melting point fiber binder (hereinafter referred to as LMF) and high melting point fibers (hereinafter referred to as SF) such as polyester-based, polyolefin-based at a predetermined fineness ratio and weight ratio After manufacturing through normal plush process, low-frequency absorbing material such as rubber is placed on the surface of high-density sound absorbing material and laminated by using heat or adhesive so that the relatively low density sound absorbing material can be concentrated in the main noise generating area. A sound absorbing material for automobiles having improved sound absorbing and insulating performance in a region can be provided.

In the present invention, it is preferable that the high-density sound absorbing material is disposed between the non-breathable layer and the low-density sound absorbing material as shown in FIG. 1, or the non-breathable layer is disposed between the high-density sound absorbing material and the low density sound absorbing material as shown in FIG. In the case where the non-breathable layer is disposed between the high density sound absorbing material and the low density sound absorbing material, the sound absorbing performance may be excellent, and thus the noise reducing ability may be excellent.

The difference in the sound absorbing and insulating performance between the structure of the sound absorbing material of the present invention and the existing material configuration as described above will become more apparent from the examples described later. However, the present invention is not limited to the following examples.

Example 1

Melting point 120 ° C, length 51mm, 30% by weight of sheath-core low melting polyester fiber of 4 denier, and melting point 255 ° C, length 51mm, 70% by weight of polyester staple fiber of 6 denia After the needle punching process, a high-density sound absorbing material was manufactured to have a thickness of 5 mm and a weight (surface density) of 800 g / m2, and a melting point of 120 ° C., a length of 51 mm, and a sheath-core type low melting point polyester fiber of 4 deniers. 15% by weight of 30% by weight of polyester staple fiber with melting point of 255 ° C, length 51mm, and 3 denier of single fineness, 20% by weight of polyester staple fiber with melting point of 255 ° C, length of 51mm and shortness of 6 denier (Surface Density) A low density sound absorbing material was produced at 1200 g / m 2. As the non-breathable layer, ordinary synthetic rubber having a weight (surface density) of 2000 g / m 2 was used.

The high-density sound absorbing material is manufactured by the conventional bonding and forming process, and the high-density sound absorbing material is disposed between the non-breathable layer and the low-density sound absorbing material. % Was obtained.

EXAMPLES 2-4

It was prepared in the same manner as in Example 1 except that the application areas of the high density sound absorbing material and the non-breathable layer of Example 1 were changed as shown in [Table 1].

EXAMPLES 5-8

It was prepared in the same manner as in Example 1 except that the application area of the high density sound absorbing material of Example 1 was changed to 100% and the application area of the non-breathable layer was changed as shown in [Table 1].

Comparative Example 1

 Of the sound absorbing material of Example 1 was prepared in the same manner as in Example 1 except that the application area of the high-density sound absorbing material 10%, the non-breathable layer is not applied.

Comparative Example 2

Except that the application area of the high-density sound absorption material of the sound absorbing material of Example 1 was 100%, the application area of the non-breathable layer was 100% was prepared in the same manner as in Example 1.

Comparative Example 3

A separate EVE layer having a weight (surface density) of 4000 g / m 2 and a thickness of 2 mm was attached, and the same procedure as in Example 1 was carried out except that polyurethane foam was used as the sound absorbing material. However, in the indoor noise evaluation, a product formed by foaming urethane foam on the YBT layer was used.

The sound absorbing performance of the specimens of the sound absorbing materials of the above Examples and Comparative Examples was measured using a reverberation chamber test equipment, and the sound source generated after placing the sound absorbing material of 0.7-1.44㎡ in the reverberation chamber with the test equipment which is a reduction of the existing reverberation chamber was walled. The sound absorption rate of the sound absorbing material is measured by the incidence of the incident light reflected on the sound absorbing material. At this time, the sound absorption rate is higher, the better. In addition, the sound insulation performance of the specimens of the Examples and Comparative Examples was measured using the Apamat test equipment, and the higher the value, the better.

The final product of the above Examples and Comparative Examples was analyzed and compared with the conventional specifications through the interior noise of the diesel engine through the AutoSEA noise, vibration analysis simulation program is shown in Table 2.

division Overall characteristic Sound insulation material composition Sound absorbing material composition Non-breathable layer High density sound absorbing material Low density sound absorbing material Weight (kg / ㎡) Thickness (mm) Thickness (mm) Surface density Application area ratio (%) Thickness (mm) Surface density Application area ratio (%) Thickness (mm) Surface density Application area ratio (%) Example 1 2.60 21 One 2000 50 5 800 50 15 1200 100 Example 2 2.92 21 One 2000 50 5 800 90 15 1200 100 Example 3 2.76 21 One 2000 50 5 800 70 15 1200 100 Example 4 2.44 21 One 2000 50 5 800 30 15 1200 100 Example 5 3.8 21 One 2000 90 5 800 100 15 1200 100 Example 6 3.40 21 One 2000 70 5 800 100 15 1200 100 Example 7 3.00 21 One 2000 50 5 800 100 15 1200 100 Example 8 2.60 21 One 2000 30 5 800 100 15 1200 100 Comparative Example 1 1.28 20 One 2000 0 5 800 10 15 1200 100 Comparative Example 2 4.00 21 One 2000 100 5 800 100 15 1200 100 Comparative Example 3 5.7 20 2 4000 100 18 1700 100 - - -

division Total weight (㎏ / ㎡) Sound absorption rate evaluation result Sound Insulation Result SEA simulation evaluation result Workability Weight reduction effect (%) (comparative example 3) Example 1 2.60 ◎ ○ ○ ◎ 54 Example 2 2.92 ◎ ○ ○ ○ 49 Example 3 2.76 ◎ ○ ○ ◎ 52 Example 4 2.44 ◎ ○ ○ ◎ 57 Example 5 3.80 ◎ ○ ◎ ○ 33 Example 6 3.40 ◎ ○ ◎ ○ 40 Example 7 3.00 ◎ ○ ○ ○ 47 Example 8 2.60 ◎ ○ ○ ○ 54 Comparative Example 1 1.28 ◎ ○ × ◎ 78 Comparative Example 2 4.00 × ◎ ○ × 30 Comparative Example 3 5.70 standard standard standard × -

◎: Excellent, ○: Normal, ×: Poor.

As described above, according to the present invention, the sound absorbing material of the present invention achieves a weight reduction of about 50% compared to the sound absorbing material with each layer disposed in the same area, thereby improving the fuel efficiency of the vehicle and at the same time improving the workability. In particular, while blocking the noise caused by the low frequency of the diesel engine, it has the effect of relatively lower the manufacturing cost of the product.

1 is a cross-sectional view of an example of a sound absorbing material for automobiles according to the present invention.

2 is a cross-sectional view of an example of a sound absorbing material for automobiles according to the present invention.

3 is a plan view of an example of a sound absorbing material for automobiles according to the present invention.

* Explanation of symbols for main parts of the drawings

1: low density sound absorber 2: high density sound absorber

3: non-breathable layer 4: dash panel

Claims (3)

In the sound absorbing material for automobiles composed of three layers of sound absorbing materials having different apparent densities composed of low melting point fibers (LMF) and high melting point fibers (SF), The automobile sound absorbing material is a three-layer layer consisting of a low density sound absorbing material, a high density sound absorbing material disposed at 40 to 100% of the area of the low density sound absorbing material, and a non-breathable layer made of rubber or resin material disposed at 10 to 90% of the area of the high density sound absorbing material. The structure, and the sound absorbing material for a vehicle, characterized in that one surface of the low density sound absorbing material is disposed in contact with the noise generating portion. The sound absorbing material for automobiles according to claim 1, wherein the three-layer structure is a structure in which the high density sound absorbing material is disposed between the non-breathable layer and the low density sound absorbing material, or a non-breathable layer is arranged between the high density sound absorbing material and the low density sound absorbing material. The sound absorbing material for automobiles according to claim 1, wherein the low density sound absorbing material has a surface density of 500 to 2000 g / m 2, and the high density sound absorbing material has a surface density of 500 to 2000 g / m 2.