JP2009298339A - Road surface side sound absorption floor undercover for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop/provide a road surface side sound absorption floor undercover for an automobile establishing sound absorption performance of large sound prevention effect and surface water repellent and using a base material having an expansion property and excellent in durability strength. <P>SOLUTION: As a means for solving the problem, the road surface side sound absorption floor undercover for the automobile characterized in that in the undercover, a road surface side sound absorption material is stuck/provided on any one surface or both surfaces of a surface or a back surface between a reinforcement layer and a core material and a sound absorption structure is provided at the road surface side becoming a secondary sound source is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automobile road surface side sound absorbing floor under cover.

  Originally, the purpose of attaching the under cover is to improve the aerodynamic performance and to improve the handling characteristics, thereby improving the maximum speed and acceleration, and further improving the fuel efficiency and removing dust, sand, stone, mud, etc. This is to protect the surrounding area.

However, recently, as part of measures against pollution such as vibration and noise, the sound insulation effect of the under floor is large, and a method of setting a sound insulation layer on the middle layer and a sound absorption layer on both sides or one side has been taken. The sound-absorbing material has problems with sound absorption measures and attachment strength due to water, mud, etc., and tends to increase costs. And as an intermediate layer material for the under floor, PP is mainly used. However, as the under floor having a plate thickness of 2.0 mm (2000 g / m ² ) and a large area, an increase in weight is a big problem.

  Therefore, in addition to the above-mentioned object (0002), it is desired that the undercover from now on use a base material that has both sound absorption performance and surface water repellency, is expandable and has excellent strength.

  Therefore, in order to solve the problems and problems described above, we invented an undercover for a vehicle that uses a base material that has excellent soundproofing effect, has both sound absorption performance and surface water repellency, and has expandability and excellent strength. Have been filed (JP 2006-240408).

  However, a new problem has occurred that the undercover for automobiles of the above invention cannot achieve both durability and sound absorption.

In addition, the automobile undercover that has been filed so far is introduced. (See Patent Documents 1 to 3.)
JP2004-169616 JP2002-348767 JP-A-9-258740

  Accordingly, in order to solve the above-mentioned problems, the present invention establishes a sound absorbing performance and surface water repellency with a large soundproofing effect, and uses a base material that is inflatable and has excellent durability, and is used for a road surface side sound absorbing floor for automobiles. It is to develop and provide an undercover.

  As a means for solving this problem, the under cover is provided by adhering a road surface side sound absorbing material on one or both of the front surface and the back surface between the reinforcing layer and the core material, and on the road surface side serving as a secondary sound source. A sound absorbing structure is provided.

  As an effect of the present invention, by adhering a water-repellent nonwoven fabric to one or both of the front and back surfaces between the reinforcing layer and the core material, both durability and water absorption can be achieved, and a secondary sound source and By installing the sound absorbing material on the road surface side, the soundproofing effect of the vehicle interior noise is excellent, the sound absorption rate is high in the high frequency range, and the noise level change due to the installation of the sound absorbing material on the road surface side and the overall interior of the room There are extremely beneficial effects such as a low noise level.

  As the best mode of the present invention, it is important to improve the productivity and reduce the cost by unifying and standardizing the plate thickness and shape of the members within the allowable range of quality, strength and performance.

  Therefore, when one embodiment of the present invention is described in detail with reference to FIGS. 1 to 3, a reinforcing material (2a) such as glass fiber and an olefin resin (2b) capable of dealing with a plate thickness of 1.0 mm to 10.0 mm are provided. A core material (2) which is provided by mixing and reinforcing fiber such as glass fiber and a foaming agent by heating and expanding, to reduce the specific gravity to 0.05 to 0.85, increase the weight and rigidity, and add sound absorption performance ), And an under cover integrally formed by providing a reinforcing layer (1) such as an olefin resin on one side or both sides of the core (2), the under cover is between the reinforcing layer (1) and the core (2). Consists of a road-side sound-absorbing floor undercover for automobiles, characterized in that a road-side sound-absorbing material is attached to either one or both of the front and back surfaces, and a sound-absorbing structure is provided on the road surface side that serves as a secondary sound source. Is done.

  FIG. 4 shows an illustration of the road surface sound absorption mechanism of the undercover. FIG. 5A shows an illustration of a chipping sound mechanism by an undercover, and FIG. 5B shows chipping sound improvement data.

  FIG. 6 is data showing changes in the noise level due to the installation of a sound absorbing material (sound absorbing structure) on the road surface side.

  Next, the three conditions necessary for an undercover having both excellent sound absorption performance and surface water repellency, which are the subject of the present invention, and having excellent expandability and strength are shown above. The reason will be explained. First, if the overall thickness including the reinforcing material (2a) is thick, the sound absorption is increased. In general, in order to increase the efficiency of sound absorption, the 1/4 wavelength at which the sound pressure is maximized. A sound-absorbing material with a thickness that can take Further, based on specific data on what happens when there is no plate thickness, the effect of the thickness of the base material in FIG. 1 on the sound absorption rate is shown in FIG. 7 when the plate thickness is 1.0 mm. While the rate is about 1.5%, it is 57% when the plate thickness is 10.0 mm. (However, the average value of 500 to 5 kHz) The reason why the plate thickness has a certain width is that when designing a car, the design standard of the vehicle height is determined, and there is a part where the thickness cannot be removed. In order to come out, a degree of freedom is required for thickness. Moreover, it is because it is desirable to use a terminal compressed to 1.0 mm in order to prevent water absorption.

  In addition, when we introduce the comparison of bending strength and weight with the conventional PP product about the reason why the specific gravity is 0.05 to 0.85 and the light weight and rigidity are increased, as shown in Fig. 8, compared with the conventional product. The developed product can be made thicker, lighter per unit area, and more rigid. Further, when the plate thickness is 6.0 mm, the rigidity tends to further increase.

  As shown in Fig. 9, two 50mm x 50mm sample specimens with different thicknesses are completely immersed in distilled water and taken out after 2 hours. The surface water was wiped off with a dry cloth and weighed immediately. However, the cut surface was sealed so as not to absorb water from the cross section of the sample. As a result, when the test piece floor under cover (FUC) is 1.5 t, the weight change rate is 0.6, and when the test piece floor under cover (FUC) is 6.4 t, the average value of the weight change rate is 1.1. In either plate thickness, there is a tendency that almost no water is absorbed. Further, by reducing the plate thickness, the water absorption rate is low, and compressing the plate thickness of the product terminal is effective as a technique for preventing water absorption.

  In addition, as a result of confirming based on data what kind of core material is added with the sound absorption performance, in the reverberation chamber method sound absorption rate evaluation according to JIS 1409, the sound absorption performance of the core material shown in FIG. Regarding the effect of the reinforcing layer on the sound absorption, when compared with conventional PP products, when only the core material is used, and when the core material and the reinforcing layer are attached, the maximum value is about 38 times that is not comparable. High sound absorption was confirmed.

  Next, the local cross-sectional structure of the undercover will be described. Conventionally, GF (glass fiber) and PP material are mixed in the core material, and a reinforcing layer (1) such as a PP film having a thickness of 50 to 500 μm on both surface portions. However, as shown in FIGS. 1 to 3, the undercover of the present invention has water repellency on either the front surface or the back surface between the conventional core material (2) and the reinforcing material (1). A nonwoven fabric (3) is attached and provided, and a sound absorbing material (4) is installed on the road surface side serving as a secondary sound source. In addition, if the said water-repellent nonwoven fabric (3) sticks and uses it not only on one side but on both surfaces according to a condition, the further waterproof and soundproofing effect can be anticipated.

  In addition, as shown in FIG. 12, the engine undercover provided in one lower part of the engine is the same as in the previous application (Japanese Patent Application Laid-Open No. 2006-240408) as to the type and attachment location of each part of a vehicle such as an automobile (CA). (EUC), three floor undercovers (FUC) provided at the lower part of the floor, front mudguards (FMG) provided at the two tire house parts on the left and right of the rear wheel, and rear parts provided at the two tire house parts on the left and right of the rear wheel There are four types of mudguards (RMG), and they are provided at a total of eight locations.

  The sound-absorbing undercover for automobiles according to the present invention establishes sound-absorbing performance and surface water repellency with a large soundproofing effect, and is compatible with both durability and water absorption by using a base material that is inflatable and has excellent durability. In addition, since it has an excellent soundproofing effect for vehicle interior noise, it has industrial applicability in terms of contributing to the automobile industry market.

FIG. 3 is a partial cross-sectional structure view of an undercover according to an embodiment of the present invention. FIG. 3 is a partial cross-sectional structure view of an undercover according to an embodiment of the present invention. FIG. 3 is a partial cross-sectional structure view of an undercover according to an embodiment of the present invention. It is a reference figure which shows one Example of this invention and shows the illustration of the road surface side sound absorption mechanism of an undercover. An embodiment of the present invention is shown, wherein (A) is an illustration of a chipping sound mechanism by an undercover, and (B) is chipping sound improvement data. It is the graph which showed the test data of this invention, and showed the change of the noise level by having installed the sound-absorbing material on the road surface side. It is the graph which showed the test data of this invention and showed the influence which base material thickness has on a sound absorption coefficient. The test data of this invention is shown, and the comparison data of bending strength between the product of the present invention and the conventional PP product is shown. The test data of this invention is shown, and the relationship between the plate thickness of the substrate and the weight change rate (water repellency) is shown. It is the graph which showed the test data of this invention and showed the influence which the sound absorption performance of a core material and a reinforcement layer have on sound absorption. It is the graph which showed the test data of this invention and represented the influence which the Example of this invention has on a sound absorption coefficient. It is a perspective view which shows the usage example of this invention and shows the undercover attachment point of a motor vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reinforcing layer, such as olefin resin 2 Core material 2a Reinforcing material, such as glass fiber 2b Olefin resin 2c Foaming agent 3 Water repellent nonwoven fabric 4 Sound absorbing material EUC Engine under cover FUC Floor under cover FMG Front mud guard RMG Rhea mud guard

Claims (1)

Glass fiber and other reinforcing materials (2a) and olefinic resin (2b) that can accommodate a plate thickness of 1.0 mm to 10.0 mm are mixed and provided, and the reinforcing fibers such as glass fiber and the foaming agent are heated and expanded. A specific gravity of 0.05 to 0.85 and a low specific gravity to improve weight and rigidity, and to add sound absorption performance, and a reinforcing layer such as an olefin resin on one or both sides of the core (2) In the under cover integrally formed by providing (1), the under cover has a road surface side sound absorbing material (3) attached to either one or both of the front and back surfaces between the reinforcing layer (1) and the core material (2). A road-side sound-absorbing floor undercover for automobiles, characterized in that a sound-absorbing structure is provided on the road-side that is worn and provided as a secondary sound source.