Method for improving acoustic cavity resonance noise of air chamber cavity of air spring

Abstract

The invention discloses a method for improving acoustic cavity resonance noise of an air spring air chamber cavity, which comprises the following steps of: establishing an air spring model, analyzing and calculating the modal of an air spring air chamber, and identifying the structural modal of the cavity at the air inlet of the air spring air chamber within a set frequency range; setting a sound cavity modal frequency according to the structure modal frequency, and ensuring that the difference between the sound cavity modal frequency and the cavity structure modal frequency is more than 15%; according to the set acoustic cavity mode frequency, the sectional area of an air inlet of the cavity and the volume of the cavity are adjusted through the Helmholtz formula, decoupling of the acoustic cavity mode and the structural mode is achieved, and resonance noise is avoided; by reasonably adjusting the sectional area of the air inlet of the air chamber cavity of the air spring and the volume of the cavity, decoupling of the acoustic cavity mode and the structural mode of the air chamber cavity is achieved, and the acoustic cavity resonance noise problem of the air chamber cavity of the air spring is avoided.

Description

Technical Field

[0001] This invention relates to the field of air spring noise technology, and more specifically to a method for improving the resonance noise of the air spring chamber cavity. Background Technology

[0002] Air springs, as a key component for improving automotive comfort, are widely used in high-end models. However, under bumpy road conditions, the air spring chamber cavity is prone to generating acoustic cavity resonance noise, with the frequency range concentrated between 700 and 1500 Hz. For example, in a certain luxury model, the high-order structural mode of the air chamber cavity inlet coupled with the acoustic cavity mode caused gas to impact the cavity sidewall, resulting in resonance noise.

[0003] In existing technologies, conventional methods for improving air spring noise mainly include: 1. Reducing noise radiation by strengthening the air spring housing structure. However, this method can only suppress noise to a limited extent and often requires significant design modifications, leading to increased weight and cost. 2. Reducing structural noise transmission by optimizing the vibration isolation system. However, the improvement effect is limited by component compatibility and can easily trigger a chain of design changes, extending the development cycle. Therefore, the above methods cannot fundamentally solve the coupling problem between acoustic cavity modes and structural modes, and the noise optimization is limited. In addition, structural changes or the addition of new components require repeated verification, resulting in long decision-making cycles and a large workload, which seriously affects the efficiency and economic benefits of vehicle development. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for improving the acoustic cavity resonance noise of an air spring chamber. By reasonably adjusting the cross-sectional area of ​​the air inlet and the volume of the air spring chamber, the acoustic cavity mode and structural mode of the chamber are decoupled, thus avoiding the occurrence of acoustic cavity resonance noise problems in the air spring chamber.

[0005] The technical solution of the present invention is as follows: In a first aspect of the present invention, a method for improving cavity resonance noise in an air spring chamber is provided, comprising the following steps: Step 1: Establish an air spring model, perform modal analysis and calculation on the air spring chamber, and identify the structural modes of the cavity at the air inlet of the air spring chamber within a set frequency range; Step 2: Set the acoustic cavity modal frequency according to the structural modal frequency, ensuring that the acoustic cavity modal frequency differs from the cavity structure modal frequency by more than 15%. Step 3: Based on the set acoustic cavity modal frequencies, adjust the cross-sectional area of ​​the cavity air inlet and the cavity volume using the Helmholtz formula to decouple the acoustic cavity modes from the structural modes, thereby avoiding resonance noise.

[0006] In some embodiments of the present invention, in step one, the set frequency range is 700-1500Hz. In some embodiments of the present invention, if there are multiple cavities at the air inlet of the air spring chamber, when setting the modal frequency of the acoustic cavity, the modal frequencies of each acoustic cavity are staggered by more than 15% and are in a non-integer multiple relationship.

[0007] In some embodiments of the present invention, in step three, the Helmholtz formula is as follows:

[0008] In the formula, f is the modal frequency of the acoustic cavity, c is the speed of sound, L is the characteristic length of the cavity inlet, A is the cross-sectional area of ​​the cavity inlet, and V is the cavity volume.

[0009] In some embodiments of the present invention, in step three, the cross-sectional area of ​​the air inlet of the mold cavity is adjusted by adjusting the diameter of the air inlet of the mold cavity.

[0010] In some embodiments of the present invention, in step three, the adjustment of the cavity volume is achieved by adjusting the position of the cavity partition.

[0011] In some embodiments of the present invention, in step one, finite element software is used to perform modal analysis and calculation of the air spring chamber.

[0012] In some embodiments of the present invention, after adjusting the cross-sectional area of ​​the air inlet and the volume of the cavity, the sound pressure distribution of the air spring chamber is simulated, and the scheme is determined based on the simulation results.

[0013] In some embodiments of the present invention, when simulation results show that there is no concentration of sound pressure energy near the cavity air inlet, the adjusted cross-sectional area of ​​the cavity air inlet and the cavity volume are used as improvement solutions.

[0014] In some embodiments of the present invention, when simulation results show that there is a concentration of sound pressure energy near the air inlet of the cavity, the position of the baffle inside the cavity is further adjusted until the concentration of sound pressure energy disappears, and the adjusted cross-sectional area of ​​the air inlet and the cavity volume are used as improvement solutions.

[0015] One or more technical solutions of the present invention have the following beneficial effects: (1) This invention addresses the physical root cause of noise generation (modal coupling), and can significantly reduce mid-to-high frequency noise (typically in the 700-1500Hz range) caused by acoustic cavity resonance. The expected noise reduction effect can reach 5-10dB(A), effectively solving the "whistling" noise problem that occurs when electric vehicles are driving on bumpy roads. Compared with the traditional method of setting a muffler in the external pipeline of the air spring or only adding sound-absorbing materials inside, this invention does not require adding too many extra components. It mainly achieves the goal by optimizing the existing structural parameters. Therefore, it has significant advantages such as low cost, easy integration, and no change to the basic structure and main performance of the air spring, and is more suitable for promotion and application in mass-produced models.

[0016] (2) The method provided by the present invention improves the resonance noise of the air spring chamber cavity by changing the diameter of the cavity inlet and adjusting the cavity volume by the partition. It is a local and refined modification inside the air spring product. The method mainly relies on mature computer-aided engineering (CAE) tools (such as finite element analysis and acoustic simulation) for early design and verification. It can complete the optimization and solidification of the scheme before the physical sample is manufactured. This greatly shortens the trial and error cycle and test cost of product development and speeds up the problem-solving speed. For vehicle development projects with tight decision-making cycles and strict cost control, it has extremely high commercial application value and market competitiveness. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the two cavities V1 and V2 at the air inlet of the air spring of the present invention; Figure 2 A schematic diagram showing the partition plate installed inside the V2 type air spring cavity of the present invention; Figure 3 This is a diagram showing the optimized results of the present invention. Detailed Implementation

[0018] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Explanation of relevant technical terms: 1. Air spring: A suspension element that uses compressed air as an elastic medium. It is widely used in automotive suspension systems to replace traditional steel coil springs.

[0021] 2. Air spring chamber: refers to the chamber inside an air spring used to contain and seal compressed air.

[0022] 3. Air spring chamber (acoustic cavity): refers to a gas-containing cavity with a fixed shape, which is enclosed by the air spring shell, diaphragm, partition and other structures.

[0023] 4. Resonance noise: When the frequency of external excitation is consistent with or close to the inherent vibration frequency of a system, the system will resonate, causing the vibration amplitude to be amplified sharply, thereby generating strong and unpleasant noise.

[0024] In this patent, it specifically refers to the harsh noise generated in the 700-1500Hz frequency range due to the frequency coupling (i.e., resonance) between the "structural mode" and the "acoustic cavity mode" of the air spring.

[0025] 5. Structural mode: refers to the inherent, free vibration characteristics of a mechanical structure (such as the shell or partition of an air spring). Each structural mode corresponds to a specific vibration frequency (structural modal frequency) and a specific vibration mode (mode shape).

[0026] 6. Cavity mode: refers to the resonant characteristics of sound waves (air pressure fluctuations) within a closed or semi-closed cavity (such as the air chamber of an air spring). Similar to structural modes, each cavity mode also corresponds to an inherent resonant frequency (cavity mode frequency) and a specific sound pressure distribution pattern.

[0027] Example 1 In a typical embodiment of the present invention, a method for improving the cavity resonance noise of an air spring is proposed, comprising the following steps: Step 1: Establish an air spring model, perform modal analysis and calculation on the air spring chamber, and identify the structural modes of the cavity at the air inlet of the air spring chamber within a set frequency range; Step 2: Set the acoustic cavity modal frequency according to the structural modal frequency, ensuring that the acoustic cavity modal frequency differs from the cavity structure modal frequency by more than 15%. Step 3: Based on the set acoustic cavity modal frequencies, adjust the cross-sectional area of ​​the cavity air inlet and the cavity volume using the Helmholtz formula to decouple the acoustic cavity modes from the structural modes, thereby avoiding resonance noise.

[0028] The method of this embodiment will be described in detail below: Step 1: Establish an air spring model, perform modal analysis and calculation on the air spring chamber, and identify the structural modes of the cavity at the air inlet of the air spring chamber within a set frequency range.

[0029] Specifically, firstly, an air spring network model is established, and then finite element software is used to perform modal analysis and calculation on the air spring chamber, identifying and recording all mode shapes of the cavity structure near the air inlet within the 700-1500Hz range.

[0030] Step 2: Set the acoustic cavity modal frequency according to the structural modal frequency, ensuring that the acoustic cavity modal frequency differs from the cavity structure modal frequency by more than 15%.

[0031] Specifically, the frequency range of the acoustic cavity modal is set according to the modal avoidance principle: for example, if the air inlet has a cavity structure mode of 1000Hz, the frequency range is set... Figure 1 The acoustic modes of the air chambers V1 and V2 of the air spring are fv1 and fv2. Then, fv1 and fv2 cannot be within the range of 1000Hz±15%, and the settings of fv1 and fv2 cannot be integer multiples of each other; that is, fv1 and fv2 must be greater than 1150Hz or less than 850Hz, and fv1 / fv2≠n, fv2 / fv1≠n; (n is a natural number).

[0032] Step 3: Based on the set acoustic cavity modal frequencies, adjust the cross-sectional area of ​​the cavity air inlet and the cavity volume using the Helmholtz formula to decouple the acoustic cavity modes from the structural modes, thereby avoiding resonance noise.

[0033] Specifically, the Helmholtz formula is as follows:

[0034] In the formula, f is the modal frequency of the acoustic cavity, c is the speed of sound, L is the characteristic length of the cavity inlet, A is the cross-sectional area of ​​the cavity inlet, and V is the cavity volume.

[0035] Since the speed of sound c and pi π are both constants, the required modal frequencies of the air spring chamber cavity can be set by changing the cross-section A of the cavity inlet and the cavity volume V.

[0036] Furthermore, the cross-sectional area of ​​the air inlet of the mold cavity is adjusted by adjusting the diameter of the air inlet.

[0037] Adjusting the cavity volume is achieved by adjusting the position of the cavity baffles. For example, increasing the inlet diameter from Φ5cm to Φ7cm and adding baffles inside the cavity to reduce the cavity volume can increase the modal frequency of the air chamber cavity acoustic cavity; Figure 2 As shown, by adjusting the position of the partition, the acoustic modal frequency of the air chamber cavity can be steplessly adjusted within a certain range.

[0038] The adjustment principle is that the Helmholtz formula reveals the negative correlation between A and V: To increase frequency f: A can be increased (enlarging the diameter of the air inlet) or V can be decreased (adding baffles in the cavity to reduce the gas volume).

[0039] To reduce the frequency f : You can reduce A (reduce the diameter of the air inlet) or increase V (remove the baffle to increase the gas volume).

[0040] Adjusting A (inlet diameter): This is usually relatively easy to achieve, but the range of diameter variation may be limited by other functions (such as airflow speed and intensity). Adjusting V (cavity volume): Changing the volume by adding baffles is a very effective and flexible method. Since the installation space and basic shape of the air spring are strictly limited by the overall vehicle layout, the total volume of the cavity and the approximate position and length (L) of the air inlet already have a baseline value in the initial design. Adjustments are made based on this baseline value.

[0041] After adjusting the cross-sectional area of ​​the air inlet and the volume of the air cavity, the sound pressure distribution in the air spring chamber is simulated, and a solution is determined based on the simulation results. If the simulation results show no sound pressure energy concentration near the air inlet, the adjusted cross-sectional area of ​​the air inlet and the volume of the air cavity are used as the improvement solution. If the simulation results show sound pressure energy concentration near the air inlet, the position of the baffle inside the cavity is further adjusted until the sound pressure energy concentration disappears, and the adjusted cross-sectional area of ​​the air inlet and the volume of the air cavity are used as the improvement solution.

[0042] like Figure 3 As shown, by planning the distribution of the acoustic modes of the air chamber cavity of the air spring, the structure of the acoustic modes and the structural modes of the air chamber cavity are realized, and the sound pressure level of the mid-to-high frequency noise in the vehicle in the 700~1500Hz range is optimized by 5~10dB(A).

[0043] The method for improving the acoustic cavity resonance noise of an air spring chamber provided in this embodiment first identifies the structural modal frequencies and mode shapes of the air chamber cavity in a specific frequency band by establishing a finite element model of the air spring. Then, based on the identified structural modes, the acoustic cavity modal frequencies of the air chamber are actively set to be at least 15% different from the structural modal frequencies, changing from traditional passive suppression (such as strengthening the structure and adding damping materials) to active frequency planning. Finally, through the classic Helmholtz resonator principle, the acoustic target is transformed into specific physical parameters—by finely adjusting the cross-sectional area (A) of the air inlet and the volume (V) of the cavity, the preset acoustic cavity modal frequencies are accurately achieved, thereby physically avoiding the coupling of acoustic cavity resonance and structural resonance.

[0044] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for improving the acoustic cavity resonance noise of an air spring chamber, characterized in that, Includes the following steps: Step 1: Establish an air spring model, perform modal analysis and calculation on the air spring chamber, and identify the structural modes of the cavity at the air inlet of the air spring chamber within a set frequency range; Step 2: Set the acoustic cavity modal frequency according to the structural modal frequency, ensuring that the acoustic cavity modal frequency differs from the cavity structure modal frequency by more than 15%. Step 3: Based on the set acoustic cavity modal frequencies, adjust the cross-sectional area of ​​the cavity air inlet and the cavity volume using the Helmholtz formula to decouple the acoustic cavity modes from the structural modes, thereby avoiding resonance noise.

2. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, In step one, the set frequency range is 700-1500Hz.

3. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, If there are multiple cavities at the air inlet of the air spring chamber, when setting the modal frequencies of the acoustic cavities, the modal frequencies of each acoustic cavity should be staggered by more than 15% and be in a non-integer multiple relationship.

4. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, In step three, the Helmholtz formula is as follows: In the formula, f is the modal frequency of the acoustic cavity, c is the speed of sound, L is the characteristic length of the cavity inlet, A is the cross-sectional area of ​​the cavity inlet, and V is the cavity volume.

5. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, In step three, the cross-sectional area of ​​the air inlet of the mold cavity is adjusted by adjusting the diameter of the air inlet.

6. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, In step three, the cavity volume is adjusted by adjusting the position of the cavity partition.

7. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, In step one, finite element software is used to perform modal analysis and calculation of the air spring chamber.

8. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 1, characterized in that, After adjusting the cross-sectional area of ​​the air inlet and the volume of the cavity, the sound pressure distribution of the air spring chamber is simulated, and the scheme is determined based on the simulation results.

9. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 7, characterized in that, If the simulation results show that there is no concentration of sound pressure energy near the cavity air inlet, then the adjusted cavity air inlet cross-sectional area and cavity volume are used as improvement solutions.

10. The method for improving the acoustic cavity resonance noise of an air spring chamber as described in claim 7, characterized in that, If the simulation results show that there is a concentration of sound pressure energy near the air inlet of the cavity, the position of the baffle in the cavity is further adjusted until the concentration of sound pressure energy disappears. The adjusted cross-sectional area of ​​the air inlet and the cavity volume are used as improvement solutions.

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