KR20050046208A - Duplex acoustic absorber of automobile dash inner - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material for automobile dashers, and to a weight reduction by eliminating a separate sound insulating material layer and forming a double structure using only a polyester sound absorbing material, to a light weight and excellent sound absorbing dual structure polyester sound absorbing material for automobile dashes. will be. That is, in the case of the existing automobile dasher is generally using a material of the sound-absorbing and sound-proof structure applied by foaming the polyurethane foam in a high-density EVA layer of 4000g / ㎡ or more. Therefore, there are problems such as heavy weight overall, manufacturing cost rises and environmental pollution due to the difficulty of recycling. In the present invention, in order to improve such a problem, it is possible to reduce the weight by eliminating the heavy layer layer while improving the sound absorbing performance by stacking by varying the density of only the polyester sound absorbing material.

Description

 Duplex acoustic absorber for automobile dasher {Duplex acoustic absorber of automobile dash inner}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sound absorbing materials for automobile dashers. More specifically, the apparent density after mixing a low melting point fiber binder (hereinafter referred to as LMF) and a high melting point fiber (hereinafter referred to as SF) such as polyester or polyolefin in a predetermined weight ratio The present invention relates to a dash inner sound absorbing material that maximizes the sound absorption and sound insulation performance by making a needle punching and manufacturing through a general plush process and then using a heat or adhesive to make a complicated noise transmission path.

In general, the typical noise flowing into the vehicle interior is the engine permeation noise generated by the engine and transmitted through the body or air. The engine cover or hood insulator is used to suppress such noise, but the effect of removing 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 are used. Is responsible for removing most of the noise.

Therefore, in the case of dash inner, the material of the sound absorbing and insulating material specification which attached the sound insulation material layer for blocking the noise which flows in most sound absorption materials conventionally has been used conventionally. However, in recent years, automobile companies are demanding continuous vehicle weight reduction, and the sound absorbing and insulating material specification has a limitation in weight reduction. Accordingly, the present invention eliminates sound insulating material and improves sound absorption and sound insulation while dashing the new specification. We wanted to develop.

Of course, the development of sound-absorbing material specification is currently being developed or under development at home and abroad, but most of them are used to manufacture a product by inputting a predetermined binder fiber after crushing our company. In this case, due to the inability to manage our company, the sound absorbing variation is severe, and problems such as deterioration of workability due to dust generation during processing, investment cost burden due to installation of dust collector, etc., and odor when using for a long time occur. In recent years, a method widely used in the present invention is to replace a heavy sound insulating material layer with a low melting point binder such as polyester fiber and a non-woven fabric layer which is heat-bonded with a high melting point synthetic fiber. Many methods have been proposed to reduce the weight of parts by constructing two or more layers. (Japanese Patent Laid-Open Nos. 8-152890, 11-180224, 66-247202, 6-259080, 8-108500 However, these methods can achieve the effect of reducing the weight of parts by simply arranging the nonwoven fabric in a plurality of layers, but more satisfactorily the sound absorption or sound insulation of noise is achieved. There was a lack of aspects to achieve.

 Accordingly, the present inventors have come to invent a dashin sound absorber which has excellent sound absorption performance compared to the existing sound absorbing and insulating specification while minimizing the reduction of sound insulation performance and significantly reducing weight.

The present invention has been made a technical problem to keep the indoor noise of the vehicle equal to or more than the conventional sound absorbing and insulating material by significantly improving the sound absorption while reducing the weight, which is a problem of the conventional product. In other words, in the case of the existing sound absorbing and insulating specification, the interior noise was improved by mainly shielding the permeation noise of the engine. However, in the present invention, the interior noise is improved by removing the noise introduced into the room in the shortest time. The development was carried out to improve the noise. Therefore, the present invention was developed mainly for sound insulation and sound absorption, and based on the evaluation result by the test piece, the evaluation of the most reliable vehicle noise and vibration analysis program at home and abroad by AutoSEA (Statistical Energy Analysis) and the interior of the actual vehicle It was developed with emphasis on noise evaluation, and as a result, it was possible to invent sound absorbing and insulating material having indoor noise better than conventional sound absorbing and insulating material and having reduced weight by at least 40%.

According to the present invention, in a flow carpet sound absorbing material for automobiles,

In order to improve sound insulation, the surface of the relatively low density first sound absorbing material is heat-treated, and is composed of two sound absorbing materials having different apparent densities composed of LMF and SF, such as polyester or polyolefin, and the sound absorption (absorption rate) is 315. 0.5 or more in the low frequency range of ～ 1000Hz, 0.8 or more in the high frequency range of 1250Hz to 3150Hz, and sound insulation (transmission loss) is 10dB (A) or more in the low frequency range of 315 to 1000 Hz and in the high frequency range of 1250 to 3150 Hz. Provided is a dual structured sound absorbing material for an automobile dasher, characterized in that more than 15 dB (A).

Hereinafter, the present invention will be described in more detail.

Looking at the configuration of the dual-structure sound absorber for automobile dasher of the present invention, the first stage is composed of a weight of 800g / ㎡ or more, if the weight exceeds 1800g / ㎡ less weight reduction effect of the vehicle parts, difficult production in mass production For this reason, it is preferable to configure 800-1800g / m 2, and in the second stage, the weight is 800g / m 2 or more, but when it exceeds 1600g / m 2, 800-1600g / m 2 is preferable because the surface becomes too hard. In addition, it is preferable that the total weight of the laminated sound absorbing material has a weight of 1600 g / m 2 or more, in terms of sound absorbing and insulating effect, and it is preferable to perform a separate heat treatment on the surface of the sound absorbing material of the first stage. This is to shield the primary by the heat treatment film on the surface of the low-density sound absorbing material when the outside noise flows into the vehicle interior.

In more detail, in general, in the sound absorbing material specification consisting of only the sound absorbing and insulating material with a sound insulating material and the sound absorbing material, the difference in transmittance to external noise is remarkably generated. In other words, when the sound insulation material is attached, the sound insulation performance (transmission loss) is remarkably excellent since external noise is primarily shielded by the sound insulation material. However, in the case of only the sound absorbing material, there is no separate sound insulating material, so the shielding ability against external noise is significantly reduced. Accordingly, in the present invention, in order to develop a new sound insulating layer to replace the sound insulating material, as shown in FIG. 1, only a part of the surface directly attached to the steel panel 3 of the vehicle, in particular, the sound insulating material 1 A coating film was formed. In this case, the external noise is primarily shielded by the sound insulating coating film, and the transmitted noise is reabsorbed by the surface of the first stage sound absorbing material 1 and the second stage sound absorbing material 2 which are not heat treated.

Therefore, in the present invention, as in Examples 1 to 5 and Comparative Examples 1 to 5, the sound absorption and sound insulation performance were compared with the case where the surface heat treatment was performed in the case of not performing the surface heat treatment. Of course, the sound absorbing performance was not much different because it measures the sound absorbing ability of the sound passing through the sound absorbing material, but the surface heat treatment of the transmission loss was superior to about 10dB (A) or more. The difference also appeared in the driving test results.

In addition, in the present invention, it is preferable to use a higher apparent density of the second sound absorbing material than the first density of the sound absorbing material. Even when the sound absorbing material having the same surface density is used, the thickness of the first sound absorbing material is higher than that of the second sound absorbing material. Since the thickness is about three times relatively thick, the apparent density is much lower density of the first single sound absorbing material. The reason why the high density sound absorbing material is applied in the second stage is to induce sound loss by causing reflection and refraction when the noise passing through the low density material of the first stage passes through the high density material of the second stage. By applying a material having a density difference in the first stage and the second stage, continuous reflection and refraction are achieved.

In the present invention, the frequency evaluation section is limited to the range of 315 to 3150 Hz, which indicates whether the engine satisfies the frequency of interest section 315 to 3150 Hz including 800 to 1500 Hz, which is the combustion noise generated by the engine, and the booming noise required by the automotive test team. To evaluate. In the present invention, the sound absorbency (absorption rate) is 0.5 or more in the low frequency section of 315 to 1000 Hz, 0.8 or more in the high frequency section of 1250 to 3150 Hz, and is 10 dB (A) or more in the low frequency section of 315 to 1000 Hz. Sound absorption material (transmission loss) of less than -3150 kHz is provided with a sound absorbing material for automobile dasher with 15 dB (A) or more. A sound absorption performance of 0.9 means that 90% of incident sound energy is absorbed, and an overloss of 10 dB ( A) means that the sound pressure lost when sound energy passes through the material is 10dB. At this time, the sound absorption is written in Arabic numerals, Absorption Raito (Absorption Raito), the higher the value is excellent sound absorption. In case of transmission loss, it is expressed as sound pressure level of dBA, and the higher the value, the better the sound insulation.

In general, in the case of only the sound absorbing material, the difference in transmission loss is lowered by 10 dB (A) or more in the low frequency section of 315 to 1000 Hz and 20 dB (A) or more in the high frequency section of 1250 to 3150 Hz when compared with the general sound absorbing and insulating material. Of course, the transmitted sound energy is reflected from the interior of the car and can be re-absorbed by the sound absorbing material at the top to improve the interior noise of the car. However, if too much difference in transmission loss occurs as shown above, too much sound energy is generated. The sound absorption alone does not improve indoor noise. Especially in the case of dash inner, unlike the flow carpet sound absorbing material, it is the part that directly receives engine permeation. There is a need for improvement. Therefore, in the low frequency range of 315 to 1000 Hz, indoor noise can be improved only by improving the transmission loss within 10 dB (A) or less than 100 dB (A) even in the 1250 to 3150 Hz section in the low frequency section of the conventional sound absorbing and absorbing material. We tried to improve the sound insulation performance by blocking the sound energy as much as possible. Therefore, the sound absorbing performance, which is an advantage of the sound absorbing material, is improved as much as possible, and the sound insulating performance is improved within the above-described range. As a result, the entire assembly weight is satisfied by at least 40% while satisfying the noise absorbing dasher and the interior noise of the car. It has a lowering effect.

In addition, the specifications developed in the present invention were analyzed on the assumption that they were applied to a real vehicle using an AutoSEA (Stastic Energy Analysis) simulation program (Table 4). (Table 4), when the surface heat treatment of the sound-absorbing material specification was not performed and there was no significant difference in sound-absorption, the sound pressure difference was about 10 dB (A) or more. In the room noise evaluation, the surface heat treatment resulted in a level equal to or higher than that of the conventional sound absorbing and insulating material specification, but most of the surface heat treatments were inferior.

The difference in sound absorption 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: Mixing 30% by weight of low-melting point polyester fiber of 120 ° C, 51mm in length, 4denia of short fineness, and 70% by weight of polyester staple fiber of melting point 255 ° C, 51mm in length, 6denia of short fineness After the needle punching process, the second-layer high-density layer sound absorbing material was manufactured to have a thickness of 5 mm and a weight (surface density) of 1200 g / m 2, and then a sheath-core type having a melting point of 120 ° C., a length of 51 mm and a single fineness of 4 deniers. 30% by weight of low-melting polyester fiber and 50% by weight of polyester staple fiber having a melting point of 255 ° C., length of 51 mm and a single fineness of 3 denier, 20% by weight of polyester staple fiber having a melting point of 255 ° C., length of 51 mm and a short degree of dedenability of 6 denier To form a low-density layer sound absorbing material for the first stage at a thickness of 15 mm and a weight (surface density) of 1000 g / m 2, laminated on the high-density layer sound-absorbing material for the second stage, and passing it through a hot oven to bond, and then passing it through a quenching press roller. Of The sound absorbing material was subjected to surface heat treatment. The surface heat treatment condition is to set the upper roller to 120 ℃ and the lower roller temperature to room temperature, and adjust the overall thickness of the product through the hot oven and adjust the upper part of the single-stage sound absorbing material. The second stage rollers were set at 180 ℃ and the upper rollers were set at 180 ° C, and the lower roller temperature was maintained at room temperature. Finally, the upper roller is set to a temperature of 100 ℃, the lower roller is passed through the three-stage roller at room temperature to the final slow cooling, while passing through the cooling roller to quench the thickness adjustment and surface heat treatment Completed.

    After the sound absorbing material was made into an assembly state, the sound absorbing and sound insulating performance was measured by using sound absorbing and sound insulating measuring equipment, and the indoor virtual noise was analyzed and compared with the conventional specification through the AutoSEA noise and vibration analysis simulation program. Finally, the evaluation is applied to the actual vehicle and is shown in Tables 2 to 4. The vehicle used in the present invention is a domestic vehicle limited to the weight reduction of more than 40% compared to the conventional sound absorbing and insulating specifications, in the embodiment was carried out the material configuration of more than 40%.

EXAMPLES 2-6

 The weight of the first and second stages of the sound absorbing material of Example 1 was changed as shown in Table 1, and was prepared in the same manner as in Example 1 except that the weight was adjusted to 2400 g / m 2, 2600 g / m 2, and the like.

[Comparative Examples 1-6]

As in Table 1, it was prepared in the same manner as in Example 1 except that the heat treatment was not performed on the lower surface of the first-stage sound absorbing material of the sound absorbing materials of Examples 1 to 5, respectively.

Comparative Example 7

 A separate 2 mm thick EVA layer 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 vehicle interior noise evaluation, a product formed by foaming urethane foam on the YB 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 existing test equipment which is a reverberation chamber was reduced. 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.

As described above, according to the present invention, it is possible to improve the fuel efficiency of the vehicle by improving the weight increase problem caused by the insertion of the heavy layer, which is a problem of the existing dash inner sound absorbing material, and at the same time, the sound absorbency and sound insulation can be improved together with the manufacturing cost. Can be lowered relatively.

1 is a cross-sectional view of the sound absorbing material for automobile dasher according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: first stage sound absorption material 2: second stage sound absorption material

3: automobile steel panel

Claims (4)

In the automotive carpet carpet sound absorption material, In order to improve sound insulation, the surface of the relatively low density first stage sound absorbing material is heat-treated, and is composed of two levels of sound absorbing materials having different apparent densities of low melting point fiber (LMF) and high melting point fiber (SF). Is 0.5 or more in the low frequency range of 315 to 1000 Hz, 0.8 or more in the high frequency range of 1250 to 3150 Hz, and sound insulation (transmission loss) is 10 dB (A) or more in the low frequency range of 315 to 1000 Hz and high frequency of 1250 to 3150 Hz. Dual-structured sound absorbing material for a car dasher, characterized in that more than 15dB (A) in the section.  The sound absorbing material of claim 1, wherein the sound absorbing material is made of polyester, and the first stage has a surface density of 800 to 1800 g / m 2, and the second stage has a surface density of 800 to 1600 g / m 2, and the total surface density of the sound absorbing material is 1600 g / m 2 or more. Dual structure sound absorbing material for automobile dash inner.    According to claim 1, wherein the heat treatment of the first stage sound absorbing material is set to 120 to 140 ℃ for the first stage quenching press roller, the surface temperature of the second stage quenching press roller is set to 160 to 200 ℃, 100 to 120 ℃ Dual structure sound-absorbing material for automobile dasher, characterized in that the heat treatment by.    4. The dual structure sound absorber for automobile dasher according to claim 3, wherein the surface heat treatment of the first sound absorbing material is performed but only the surface of the first sound absorbing material attached to the steel panel is heat treated.