CN211918570U - Metamaterial sound insulation pad for automobile - Google Patents

Abstract

The utility model discloses a metamaterial sound insulation pad for car, include the PU foaming body and distribute in wherein quality granule, the PU foaming body includes a plurality of layers of PU foaming layer, exists between the adjacent two-layer PU foaming layer and is used for holding the space of quality granule. The utility model discloses use acoustics package metamaterial technical principle, overcome the not enough problem of low frequency transmission loss in current car gives sound insulation and fills up, effectual isolated external noise improves the acoustics environment of whole car to the influence in the car.

Description

Metamaterial sound insulation pad for automobile

Technical Field

The utility model belongs to acoustics metamaterial field especially relates to a metamaterial gives sound insulation and fills up for car.

Background

With the increasing popularity of the competition in the automotive industry in China, automotive enterprises need to implement more efficient and accurate design and control of the NVH performance (noise, vibration and harshness) of automobiles to meet the increasingly demanding requirements of users. Automotive NVH design and control relies on the efficient design of the body structure on the one hand and the efficient application of automotive acoustic package components on the other hand. And the characteristics of effectiveness, specificity and flexibility of the acoustic package part are the best way for designing and controlling the NVH performance of the automobile.

The automobile carpet sound insulation pad is one of the most important acoustic package parts of an automobile, and can effectively attenuate noise transmitted from the bottom of the automobile to the interior of the automobile. The existing automotive carpet sound insulation pad is mainly made of polypropylene fiber felt, blended felt, Polyurethane (PU) soft foamed rubber and other materials, such as an automotive carpet sound insulation pad disclosed in patent document CN103072506, an automotive carpet sound insulation pad disclosed in patent document CN106541873, a waste cotton composite automotive carpet disclosed in patent document CN101716902 and the like.

The sound insulation performance of the traditional automobile carpet sound insulation pad is controlled by the mass law, and the transmission loss logarithmic curve of the traditional automobile carpet sound insulation pad linearly increases along with the increase of frequency. This means that in the middle and low frequency region, the sound insulation performance of the automotive carpet sound insulation pad is poor, and external noise cannot be effectively isolated.

In recent years, the development of acoustic metamaterials provides a new idea for solving the problem of low frequency in sound insulation of an automobile acoustic bag. The acoustic metamaterial refers to an artificial structure or a composite material formed by periodically arranging a plurality of materials or structures according to a specific form, and has extraordinary characteristics such as band gap, negative refractive index and the like which are not possessed by natural materials. In the frequency range of the acoustic metamaterial band gap, the elastic wave cannot propagate. The structure of the automobile carpet sound insulation pad is designed by utilizing the band gap characteristic of the acoustic metamaterial, so that the sound insulation characteristic in a medium and low frequency range can be effectively improved, and the NVH level of an automobile is improved.

Disclosure of Invention

To the above problem, an object of the utility model is to provide a metamaterial gives sound insulation to fill for car uses acoustics package metamaterial technique, overcomes the not enough problem of low frequency transmission loss in current car gives sound insulation to fill, and effectual isolated external noise improves the acoustics environment of whole car to the influence in the car.

The utility model discloses a concrete technical scheme as follows: the utility model provides a metamaterial sound insulation pad for car, includes PU foaming body (polyurethane foaming body) and distributes among them 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.

Furthermore, the space for containing the mass particles is formed by butting two half holes arranged on two adjacent PU foaming layers.

Further, the PU foaming body is provided with three PU foaming layers.

Furthermore, the two adjacent PU foaming layers are adhered and fixed by spray glue.

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

Further, the method can be used for preparing a novel materialThe thickness of the PU foaming layer is 3-10 mm, and the density is 20-80 kg/m³In the meantime.

Further, the mass particles are spherical or cubic in shape.

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

Use the utility model provides a metamaterial gives sound insulation and fills up in the car that obtains before enclose, carpet and wheel package give sound insulation and fill up before outer all belong to the utility model discloses a protection range.

The utility model has the advantages of it is following and beneficial effect:

(1) the utility model discloses a metamaterial gives sound insulation and fills up, material, volume and the distribution of its quality granule can be adjusted according to actual syllable-dividing requirement, and when quality granule quality increase, local resonant frequency is less, low frequency noise in can more effectual decay car, reduces when quality granule quality, and local resonant frequency increases, intermediate frequency noise in can effectual decay car. Namely, the utility model discloses a metamaterial gives sound insulation and fills up under can effectual promotion low and medium frequency sound insulation performance, and the noise that transmits to in the car outside the separation car improves the NVH performance of whole car. Meanwhile, the local resonance frequency of the carpet sound insulation pad can be changed by adjusting the mass and the distribution density of the mass particles, so that the sound insulation performance of a specific frequency section can be adjusted;

(2) the utility model discloses a metamaterial gives sound insulation and fills up, the quality is lighter, the volume is less, satisfies car lightweight and spatial arrangement requirement.

Drawings

FIG. 1 is a finite element model of the cellular structure of the sound insulating mat of the metamaterial for the car carpet of example 1;

FIG. 2 is a graph comparing the transmission loss of the acoustical pad of example 1 with a 15mm PU foam layer (without added mass particles);

FIG. 3 is a working variation of the cell structure of the sound-insulating mat of example 1 at 2000 Hz;

FIG. 4 comparative graph of transmission loss for example 1 and the four schemes.

In the figure: 1-PU foaming layer; 2-mass particles.

Detailed Description

Example 1

As shown in fig. 1, the metamaterial sound insulation pad for the car carpet provided by the present example is provided with three PU foam layers, and one layer of mass particles is arranged between two adjacent PU foam layers, that is, two layers of mass particles are provided. The density of the PU foaming layer is 80kg/m³The thickness of a single layer is 5 mm; the mass particles are made of steel materials and are spherical, and the radius of the mass particles is 2 mm; the mass particles are uniformly distributed in the PU foaming process, and 1 mass particle is distributed between two PU foaming layers within the average range of 20mm multiplied by 20 mm; the upper PU foaming layer and the lower PU foaming layer adopt a single-sided semi-open pore design, the middle PU foaming layer adopts a double-sided semi-open pore design, the shape and the size of the open pores are consistent with those of the mass particles, and a space is reserved for the mass particles. The volume of the openings needs to be slightly less than the volume of the mass particles to create an interference fit in the fit to secure the mass particles and provide rigidity to the movement of the mass particles.

The sound insulation pad made of the metamaterial for the automotive carpet can be regarded as periodic repetition of a cellular structure, wherein the cellular structure is composed of three PU foaming layers and two layers of quality particles, the size of the cellular structure is 20mm multiplied by 20mm, and the thickness of the cellular structure is 15 mm. A finite element model of the cell structure is established, and periodic boundary conditions are set to simulate the periodic repetition of the cell structure, as shown in fig. 1. By loading the incident plane wave, the transmission loss of the metamaterial sound-insulating pad of the automobile carpet can be solved, as shown in fig. 2. From the analysis results, the transmission loss of the metamaterial sound-insulating pad for the automobile carpet provided by the embodiment is far higher than that of a PU foaming structure with the same thickness below 2500Hz, the peak value is obtained at 2000Hz, and the transmission loss is basically the same above 4500 Hz. The working deformation at the 2000Hz peak was analyzed and as shown in fig. 3, the mass particles at this frequency formed localized resonances, greatly increasing the transmission loss of the structure.

To verify the effect of mass particle mass and position on the performance of the results, the performance of example 1 and the following protocol were compared. In the first scheme, the mass particle radius is reduced to the current half, namely 1 mm; in the second scheme, two mass particles of 1mm and 2mm are adopted and are alternately distributed in the PU foaming layer; in the third scheme, the position of the existing mass particles is respectively offset by 5mm towards two directions of a plane; in the fourth scheme, the position of the existing mass particles is offset by 2mm towards two directions of the plane respectively. The transmission losses for example 1 and the four schemes are shown in figure 4. Comparing the embodiment 1 with the first scheme and the second scheme, the mass of the particles is in inverse proportion to the local resonance frequency, the mass is reduced by N times, and the resonance frequency is increased by about N ^0.5 times; the local resonance frequency is insensitive to the mass distribution of the two particles, but is more sensitive to the total mass. Comparing the example with the third and fourth schemes, it can be seen that the position of the mass particles is offset to the outside of the center, and the resonance frequency increases with the increase of the offset distance, because the offset of the position of the mass particles changes the equivalent stiffness; in order to make the metamaterial sound bag have good effect, the mass and the distribution of the mass particles need to be 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 portion of the floor and the target level of noise in a vehicle, the frequency range corresponding to the peak value of the sound insulation target is determined, the local resonance frequency is kept consistent with the target peak value frequency by adjusting the elastic modulus of the PU foaming layer and the mass particle mass, and therefore the transmission loss of the structure in the specified frequency band is improved. If the sound insulation performance target of the sound insulation pad comprises two or more peak values, two or more mass particles can be arranged in the PU layer, so that the peak value of the multi-transferable loss curve is formed, and the requirement of the sound insulation performance target is met.

While the technical content and the technical features of the specific embodiments of the invention have been disclosed, it is understood that various changes and modifications of the combination of the various features disclosed above and features not explicitly shown herein can be made by those skilled in the art within the spirit of the invention, and the scope of the invention is defined by the terms of the appended claims. The above description of embodiments is intended to be illustrative, and not restrictive, and the scope of the invention is defined by the appended 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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