CN211918570U - A kind of metamaterial sound insulation pad for automobile - Google Patents

Abstract

The utility model discloses a super-material sound insulation pad for automobiles, which comprises a PU foam body and mass particles distributed therein. The PU foam body comprises several layers of PU foam layers, and between two adjacent layers of PU foam layers There is space between the mass particles for accommodating the mass particles. The utility model applies the principle of acoustic package metamaterial technology, overcomes the problem of insufficient low-frequency transmission loss in the existing automobile sound insulation pad, effectively isolates the influence of external noise on the interior of the vehicle, and improves the acoustic environment of the entire vehicle.

Description

A kind of metamaterial sound insulation pad for automobile

technical field

The utility model belongs to the field of acoustic metamaterials, in particular to a metamaterial sound insulation pad for automobiles.

Background technique

With the increasingly fierce competition in China's auto industry, auto companies need to achieve more effective and accurate design and control of automotive NVH performance (noise, vibration and harshness) to meet the increasingly demanding needs of users. Automotive NVH design and control depend on the effective design of the body structure on the one hand, and on the effective application of automotive acoustic package parts on the other. Acoustic package parts are the best way to design and control automotive NVH performance due to their effectiveness, specificity and flexibility.

Car carpet sound insulation pad is one of the most important acoustic package parts of the car, which can effectively attenuate the noise transmitted from the bottom of the car to the inside of the car. Existing car carpet sound insulation pads are mainly made of polypropylene felt, blended felt, polyester ammonia (PU) soft foamed rubber and other materials, such as the "automobile carpet sound insulation pad" disclosed in patent document CN103072506, and the "automobile carpet sound insulation pad" disclosed in patent document CN106541873. Carpet sound insulation pad", "Waste Cotton Composite Car Carpet" disclosed in patent document CN101716902, etc.

The sound insulation performance of traditional automotive carpet insulation mats is governed by the law of mass, and the logarithmic curve of transmission loss increases linearly with frequency. This means that in the mid-low frequency region, the sound insulation performance of the car carpet sound insulation pad is poor and cannot effectively isolate external noise.

In recent years, the development of acoustic metamaterials has provided new ideas for solving the mid- and low-frequency problems of automotive acoustic packages. Acoustic metamaterials refer to artificial structures or composite materials formed by periodic arrangement of various materials or structures in a specific form, with extraordinary properties that natural materials do not possess, such as band gaps and negative refractive indices. In the bandgap frequency range of the acoustic metamaterial, elastic waves will not be able to propagate. Using the band gap characteristics of acoustic metamaterials, the structure of the car carpet sound insulation pad is designed, which can effectively improve the sound insulation characteristics in the low and medium frequency range and improve the NVH level of the car.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, the purpose of this utility model is to provide a kind of metamaterial sound insulation pad for automobiles, applying the acoustic package metamaterial technology to overcome the problem of insufficient low-frequency transmission loss in the existing automobile sound insulation pads, and effectively isolate the external noise from the inside of the car. Influence and improve the acoustic environment of the vehicle.

The specific technical scheme of the utility model is as follows: a metamaterial sound insulation pad for automobiles, comprising a PU foam (polyurethane foam) and mass particles distributed therein, and the PU foam comprises several layers of PU foam layers , there is a space for accommodating the quality particles between two adjacent PU foam layers.

Further, the space for accommodating the mass particles is formed by two half-hole butt joints arranged on two adjacent layers of PU foam layers.

Further, the PU foam body is provided with three layers of PU foam layers.

Further, the two adjacent PU foam layers are glued and fixed by spraying glue.

Further, the radius of the mass particles is 0.5-5 mm.

Further, the thickness of the PU foam layer is 3-10 mm, and the density is between 20-80 kg/m ³ .

Further, the mass particles are spherical or cubic.

Further, the quality particles are one of stone particles, rubber particles, EVA particles or steel balls.

The automobile inner front wall, outer front wall, carpet and wheel bag sound insulation pads prepared by applying the metamaterial sound insulation pad proposed by the present invention all belong to the protection scope of the present invention.

The utility model has the following advantages and beneficial effects:

(1) In the metamaterial sound insulation pad of the present invention, the material, volume and distribution of its mass particles can be adjusted according to the actual sound insulation requirements. When the mass of the mass particles increases, the local resonance frequency is small, which can more effectively attenuate the noise in the car. For low-frequency noise, when the mass of the mass particles decreases, the local resonance frequency increases, which can effectively attenuate the intermediate-frequency noise in the car. That is, the metamaterial sound insulation pad of the present invention can effectively improve the sound insulation performance of the sound insulation pad at medium and low frequencies, block the noise transmitted from outside the vehicle to the inside of the vehicle, and improve the NVH performance of the entire vehicle. At the same time, by adjusting the mass and distribution density of the mass particles, the local resonance frequency of the carpet sound insulation pad can be changed, and the sound insulation performance of a specific frequency band can be adjusted;

(2) The metamaterial sound-insulating pad of the present invention is lighter in weight and smaller in volume, and meets the requirements of lightweight and space layout of automobiles.

Description of drawings

Fig. 1 is embodiment 1 automobile carpet metamaterial sound insulation pad cell structure finite element model;

Fig. 2 is the transmission loss contrast graph of embodiment 1 sound insulation pad and 15mmPU foam layer (without adding mass particles);

Fig. 3 is the working deformation of the cell structure of the sound insulation pad of Example 1 under 2000Hz;

FIG. 4 is a comparison diagram of transmission loss between Example 1 and the four schemes.

In the figure: 1-PU foam layer; 2-quality particles.

Detailed ways

Example 1

As shown in Figure 1, the metamaterial sound insulation pad for automobile carpet provided in this example is provided with three layers of PU foam layers, and one layer of mass particles is provided between two adjacent layers of PU foam layers, that is, there are two layers of mass particles in total. The density of the PU foam layer is 80kg/m ³ , and the thickness of the single layer is 5mm; the mass particles are made of steel, spherical, and the radius is 2mm; the mass particles are kept relatively evenly distributed in the PU foam, and the two layers of the PU foam layer are the same. There is 1 mass particle distributed in the average range of 20mm×20mm; the upper and lower PU foam layers are designed with single-sided semi-open cells, and the middle PU foam layer is designed with double-sided semi-open cells. and size are consistent with the shape and size of the mass particles, leaving room for the mass particles. However, the volume of the opening needs to be slightly smaller than the volume of the mass particles, thereby forming an interference fit in the assembly to fix the mass particles and provide stiffness for the movement of the mass particles.

The car carpet metamaterial sound insulation pad provided in this embodiment can be regarded as a periodic repetition of a cellular structure. The cellular structure is composed of three layers of PU foam layers and two layers of mass particles, with a size of 20mm×20mm and a thickness of 15mm. A finite element model of the cellular structure is established, and periodic boundary conditions are set to simulate the periodic repetition of the cellular structure, as shown in Figure 1. The transmission loss of the car carpet metamaterial sound insulation pad can be solved by loading the incident plane wave, as shown in Figure 2. It can be seen from the analysis results that the transmission loss of the automotive carpet metamaterial sound insulation pad provided in this example is much higher than that of the PU foam structure of equal thickness below 2500 Hz, and has a peak value at 2000 Hz, and the transmission loss is basically the same above 4500 Hz. The working deformation at the peak of 2000Hz is analyzed, as shown in Figure 3. At this frequency, the mass particles form local resonance, which greatly increases the transmission loss of the structure.

To verify the effect of mass particle mass and location on the resulting performance, the performance of Example 1 and the following protocols were compared. In scheme 1, the radius of the mass particles is reduced to half of the current one, that is, 1mm; in scheme 2, two kinds of mass particles of 1mm and 2mm are used, which are alternately distributed in the PU foam layer; in scheme three, the existing mass particles are The position of the particle is offset by 5mm in the two directions of the plane; in scheme 4, the position of the existing mass particles is offset by 2mm in the two directions of the plane. The transmission losses of Example 1 and the four schemes are shown in Figure 4. Comparing Example 1 with Scheme 1 and Scheme 2, it can be seen that the particle mass is inversely proportional to the local resonance frequency, the mass is reduced by N times, and the resonance frequency is roughly increased by N^0.5 times; the local resonance frequency has no effect on the mass distribution of the two particles. Sensitive, but more sensitive to total mass. Comparing the example with Scheme 3 and Scheme 4, it can be seen that the position of the mass particle is offset to the outside of the center, and the resonance frequency increases with the increase of the offset distance. The reason is that the offset of the position of the mass particle changes the equivalent stiffness; The material sound packet has a good effect, and the quality and distribution of the mass particles need to be relatively uniform.

In the design process of the carpet metamaterial sound insulation pad, the sound insulation performance target of the carpet sound insulation pad can be calculated according to the sound load level of the lower part of the floor and the target level of the interior noise, and the frequency range corresponding to the peak value of the sound insulation target can be determined. The elastic modulus of the foam layer and the mass of the mass particles keep the local resonance frequency consistent with the target peak frequency, thereby improving the transmission loss of the structure within the specified frequency band. If the sound insulation performance target of the sound insulation pad includes two or more peaks, two or more mass particles can also be arranged in the PU layer to form multiple peaks of the transfer loss curve to meet the requirements of the sound insulation performance target. .

The technical content and technical features of the specific embodiments of the present invention have been disclosed above, however, it is understood that under the creative idea of the present invention, those skilled in the art can understand the various features disclosed above and those not explicitly shown here. Various changes and improvements are made to the combination, but they are all within the scope of protection of the present invention. The descriptions of the above embodiments are exemplary rather than restrictive, and the protection scope of the present invention is determined by the claims.

Claims (8)

1. The utility model provides a metamaterial sound insulation pad for car which characterized in that, includes the PU foaming body and distributes wherein the quality granule, the PU foaming body includes a plurality of layers of PU foaming layer, exists between two adjacent layers of PU foaming layer to be used for holding the space of quality granule.

2. The sound insulation cushion for the automobile metamaterial according to claim 1, wherein the space for accommodating the mass particles is formed by butt joint of two half holes arranged on two adjacent PU foaming layers.

3. The sound insulation mat as claimed in claim 1, wherein the PU foam is provided with three PU foam layers.

4. The sound insulation cushion for the automobile metamaterial according to claim 1, wherein the two adjacent PU foam layers are adhered and fixed by spraying glue.

5. The sound insulation mat for the automobile metamaterial according to claim 1, wherein the mass particles have a radius of 0.5 to 5 mm.

6. The automotive metamaterial sound insulation pad as claimed in claim 1, wherein the PU foam layer has a thickness of 3 to 10 mm.

7. The acoustical mat of claim 1, wherein said mass particles are spherical or cubic.

8. The acoustical mat of claim 1, wherein the mass particles are one of stone particles, rubber particles, EVA particles, or steel beads.

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