SOUND ABSORBER AND WHEEL HAVING SAME

Abstract

The present disclosure relates to a sound absorber and a wheel having the same. The sound absorber is configured as a rectangular hexahedral box and forms a porous double-layer Helmholtz resonance sound absorbing structure, at the same time, the sound absorber in the form of a box forms a structural resonance sound absorbing device itself, and the first-order natural mode frequency of the device is identical to that of a wheel air chamber. When the box-type sound absorbing structure is assembled in a wheel, double functions of absorbing acoustic resonance of the wheel air chamber under the organic combination of Helmholtz resonance sound absorption and structural resonance sound absorption can be realized.

Claims

1. A sound absorber, the sound absorber is mounted on a moving component in an air environment to reduce acoustic resonance, wherein the sound absorber is configured as a rectangular hexahedral box and forms a porous double-layer Helmholtz resonance sound absorbing structure, the box has two sides defining boundaries of two ends of the box in the moving direction of the moving component, the inside of the box is divided by a partition into a first cavity and a second cavity successively arranged in the moving direction of the moving component, the partition is parallel to one side of the box, two hollow tubes are mounted on the side, the two hollow tubes respectively have an orifice opened to a wheel air chamber on the side and extend into the first cavity at a distance corresponding to their lengths, a hollow tube is mounted on the partition, the hollow tube has an orifice opened to the first cavity on the partition and extends into the second cavity at a distance corresponding to its length, and the first cavity and the second cavity constitute two layered resonant cavities of the porous double-layer Helmholtz resonance sound absorbing structure.

2. The sound absorber according to claim 1, wherein the structural parameters of the box are determined by a predetermined sound absorption coefficient and a sound absorption amount of the porous two-layer Helmholtz resonance sound absorbing structure, the structural parameters comprising plate thicknesses of the partition and the side, orifice diameters and lengths of the hollow tubes, and shapes, volumes and wall thicknesses of the first cavity and the second cavity.

3. A wheel equipped with the sound absorber according to claim 1, wherein the sound absorber is mounted inside a wheel air chamber to reduce acoustic resonance.

4. The wheel according to claim 3, wherein one or more sound absorbers are mounted on a hub of the wheel.

5. The wheel according to claim 4, wherein the sound absorber is mounted in a state that the bottom surface of the box is attached to the rim bottom surface of the hub, and is arranged such that the side mounted with the two hollow tubes is used as an air incident flow side when the wheel rotates.

6. The wheel according to claim 5, wherein the sound absorber is fixed to the hub of the wheel by means of a band.

7. The wheel according to claim 6, wherein the box of the sound absorber is made of metal or plastic and forms a structural resonance sound absorbing device itself, and the first-order natural mode frequency of the structural resonance sound absorbing device is identical to that of the wheel air chamber.

8. The wheel according to claim 6, wherein the sound absorber is provided with a U-shaped groove on the top surface of the box opposite to the bottom surface of the box, and the band is embedded into the U-shaped groove and wound one circle on the hub to fix the box of the sound absorber.

9. The wheel according to claim 8, wherein two ends of the band are fastened by buckles, and the fastening force of the band can be adjusted and/or displayed by means of a fastening tool.

10. The wheel according to claim 3, wherein a plurality of sound absorbers are arranged side by side on the hub of the wheel or a plurality of sound absorbers are arranged along the circumference of the hub.

11. A wheel equipped with the sound absorber according to claim 2, wherein the sound absorber is mounted inside a wheel air chamber to reduce acoustic resonance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a schematic diagram of a sound absorber according to the present disclosure.

[0025] FIG. 2 is a schematic diagram of a mounting position of the sound absorber on a wheel.

[0026] FIG. 3 is a schematic diagram of assembly and fixing of the sound absorber and a hub.

[0027] In which: 1-side of a box, the side being mounted with two hollow tubes, 2-hollow tube, 3-hollow tube, 4-first cavity, 5-partition, 6-hollow tube, 7-second cavity, 8-U-shaped groove; 10-sound absorber, 20-hub, 30-wheel air chamber, 40-tire, 50-band.

DETAILED DESCRIPTION

[0028] The technical solution in the embodiments of the application is clearly and completely described in combination with drawings of the embodiments of the application below, and obviously, the described embodiments are part of embodiments of the application rather than all embodiments. Based on the embodiments of the application, all the other embodiments obtained by those having ordinary skill in the art without any creative works are within the protection scope of the application.

[0029] The terms ‘first’, ‘second’, ‘third’, ‘fourth’ and the like in the specification and in the claims of the application are used for distinguishing different objects but not for describing a specific sequence. Furthermore, the terms ‘comprise’ and ‘have’ as well as their any variations are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or equipment comprising a series of steps or units does not limit steps or units which have been listed, but selectively further comprises steps or units which are not listed, or selectively further comprises other inherent steps or units for the process, method, product or equipment.

[0030] Reference in the specification to ‘embodiments’ of the application means that a particular feature, structure or characteristic described in connection with the embodiments is included in at least one embodiment of the application. The appearances of the phrase ‘the embodiments’ in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in the application can be combined to other embodiments.

[0031] The present disclosure provides a sound absorber 10. The sound absorber is mounted on a moving component (as shown in FIG. 2, particularly a hub 20 of an automobile wheel equipped with a pneumatic tire 40) in an air environment (as shown in FIG. 2, particularly a wheel air chamber 30) to reduce acoustic resonance. As shown in FIG. 1, the sound absorber is configured as a rectangular hexahedral box and forms a porous double-layer Helmholtz resonance sound absorbing structure. The box has two sides defining boundaries of two ends of the box in the moving direction of the moving component, the inside of the box is divided by a partition 5 into a first cavity 4 and a second cavity 7 successively arranged in the moving direction of the moving component, the partition is parallel to one side 1 of the box, two hollow tubes 2 and 3 are mounted on the side 1, the two hollow tubes respectively have an orifice opened to the wheel air chamber on the side 1 and extend into the first cavity 4 at a distance corresponding to their lengths, a hollow tube 6 is mounted on the partition 5, the hollow tube has an orifice opened to the first cavity 4 on the partition 5 and extends into the second cavity 7 at a distance corresponding to its length, and the first cavity 4 and the second cavity 7 constitute two layered resonant cavities of the porous double-layer Helmholtz resonance sound absorbing structure. The structural parameters of the box are determined by a predetermined sound absorption coefficient and a sound absorption amount of the porous two-layer Helmholtz resonance sound absorbing structure, the structural parameters including plate thicknesses of the partition 5 and the side 1, orifice diameters and lengths of the hollow tubes, and shapes, volumes and wall thicknesses of the first cavity 4 and the second cavity 7. This will be further described below.

[0032] Based on this, the present disclosure also provides a wheel equipped with the sound absorber 10, and the sound absorber is mounted inside the wheel air chamber 30 to reduce acoustic resonance. One or more sound absorbers 10 are mounted on the hub 20 of the wheel. It is possible to arrange a plurality of sound absorbers 10 side by side on the hub 20 of the wheel or arrange a plurality of sound absorbers 10 along the circumference of the hub. As shown in FIG. 2, the sound absorber 10 is mounted in a state that the bottom surface of the box is attached to the rim bottom surface of the hub 20, and is arranged such that the side 1 mounted with the two hollow tubes is used as an air incident flow side when the wheel rotates. As shown in FIG. 3, the sound absorber 10 is fixed to the hub 20 of the wheel by a band 50 (for example, a steel band). It is particularly advantageous that the box of the sound absorber is made of metal or plastic and forms a structural resonance sound absorbing device itself, and the first-order natural mode frequency of the structural resonance sound absorbing device is identical to that of the wheel air chamber 30. As shown in FIG. 2 and FIG. 3, the sound absorber (10) is provided with a U-shaped groove 8 on the top surface of the box opposite to the bottom surface of the box, and the band 50 is embedded into the U-shaped groove and wound one circle on the hub 20 to fix the box of the sound absorber. Two ends of the band 50 are fastened by buckles, and the fastening force of the band can be adjusted and/or displayed by means of a fastening tool.

[0033] FIG. 1 shows an embodiment of the sound absorber according to the present disclosure, which is embodied as an injection-molded rectangular hexahedral box-type structure. The inside is divided into two cavities by a thin plate (partition 5), that is, a first cavity 4 and a second cavity 7, two hollow tubes 2 and 3 are mounted on one side 1 (parallel to the thin division plate in the box) of the box-type structure, and a hollow tube 6 is mounted on the thin division plate in the box.

[0034] The plane of one end orifices of the two hollow tubes 2 and 3 and the side 1 of the box-type structure are on a surface, the tubes 2 and 3 extend into the first cavity 4, the plane of one end orifice of the hollow tube 6 and the thin division plate (partition 5) in the box are on a surface, and the hollow tube 6 extends into the second cavity 7.

[0035] The two hollow tubes 2 and 3 of the box resonance sound absorbing structure shown in FIG. 1 are in communication with the wheel air chamber (or tire air chamber) 3 shown in FIG. 2, and the box resonance sound absorbing structure is mounted on the circular arc surface of the hub 2 shown in FIG. 2 to form a porous double-layer Helmholtz resonance sound absorbing structure.

[0036] The relevant parameters of the rectangular hexahedral box-type structure shown in FIG. 1 are determined by the sound absorption coefficient and sound absorption amount of the double-layer Helmholtz resonance sound absorbing structure, as described in the following formulas:

[0037] Z is acoustic impedance of the resonance structure. Z.sub.p1 is acoustic impedance of a hole of a first layer perforated structure, and Z.sub.a1 is acoustic impedance of a first layer cavity. Z.sub.p2 is acoustic impedance of a hole of a second layer perforated structure, and Z.sub.a2 is acoustic impedance of a second layer cavity.

[00001]$Z_{p1}=\frac{\rho }{{\delta }_1}\sqrt{8\gamma \omega }\left(1+\frac{t_1}{d_1}\right)+j\frac{\omega \rho }{{\delta }_1}\left[\sqrt{\frac{8\gamma }{\omega }}\left(1+\frac{t_1}{d_1}\right)+t_1+0.85d_1\left(1-1.47\sqrt{{\delta }_1}+0.47\sqrt{{\delta }_1^3}\right)\right]$$Z_{p2}=\frac{\rho }{{\delta }_2}\sqrt{8\gamma \omega }\left(1+\frac{t_2}{d_2}\right)+j\frac{\omega \rho }{{\delta }_2}\left[\sqrt{\frac{8\gamma }{\omega }}\left(1+\frac{t_2}{d_2}\right)+t_2+0.85d_2\left(1-1.47\sqrt{{\delta }_2}+0.47\sqrt{{\delta }_2^3}\right)\right]$$Z_{a1}=-j\rho c\cot \left(\frac{\omega D_1}{c}\right)$$Z_{a2}=-j\rho c\cot \left(\frac{\omega D_2}{c}\right)$$Z=Z_{p1}+\frac{z_{a1}\left(z_{a2}+z_{p2}\right)}{Z_{a1}+Z_{a2}+Z_{p2}}$

[0038] In the formulas, ρ is air density, c is sound velocity of air, ω=2πf, and f is frequency. γ is an air movement viscosity coefficient, γ=15×10.sup.−6 m.sup.2/s. t.sub.1 and t.sub.2 are respectively thicknesses of the first layer plate and second layer plate, d.sub.1 and d.sub.2 are respectively hole diameters of the first layer plate and second layer plate, δ.sub.1 and δ.sub.2 are respectively perforation rates of the first layer plate and second layer plate, and D.sub.1 and D.sub.2 are respectively thicknesses of the first layer cavity and second layer cavity. p Z.sub.r is relative acoustic impedance of the resonance structure.

[00002]$Z_r=\frac{Z}{\rho c}$

[0039] If R is the real part of Z.sub.r and X is the imaginary part of Z.sub.r, the sound absorption coefficient a of the resonance sound absorbing structure is:

[00003]$\alpha =\frac{4R}{{\left(R+1\right)}^2+{\left(X+1\right)}^2}$

[0040] Calculation formula of sound absorption amount is: A=αs

[0041] A is the sound absorption amount of the resonance sound absorbing structure.

[0042] S is the sum of cross-sectional areas of the hollow tube 2 and the hollow tube 3 of the resonance sound absorbing structure.

[0043] The first-order natural mode frequency of the rectangular hexahedral box-type structure shown in FIG. 1 as a resonance sound absorbing structure is identical to that of the wheel air chamber. The natural frequency meets the design requirements by means of plate thickness and shape adjustment, and the adjustment is implemented by calculation of finite elements.

[0044] The upper surface of the porous double-layer resonance sound absorbing structure shown in FIG. 1 is designed with a U-shaped groove 8 for mounting the sound absorbing structure to the hub 1 shown in FIG. 3. As shown in FIG. 2 and FIG. 3, the mounting method is: a steel band as the band 3 passes through and is embedded into the U-shaped groove 8, and is wound one circle on the hub to press the resonance sound absorbing structure against the hub for fixing. Since the steel band is wound one circle on the hub, one or more sound absorbing structures can be fixed on the hub. The steel band joints are fastened with buckles, and the fastening force can be displayed by a fastening tool to judge the mounting firmness.

[0045] The embodiments of the application are described in detail above, particular examples are used herein to explain the principle and embodiments of the application, and the above description of the embodiments is only used to help understanding the methods and core concept of the application; and meanwhile, for those having ordinary skill in the art, according to the idea of the application, there will be changes in the specific implementation mode and application scope, in conclusion, the contents of the specification shall not be construed as a limitation of the application.