A method for controlling vibration and abnormal noise of automobile subwoofer

Abstract

The present invention relates to the field of automobile manufacturing, and more specifically, to a method for controlling vibration and abnormal noise of a vehicle subwoofer. The method establishes a finite element model of the vehicle body in its complete state. First, the dynamic stiffness of the subwoofer's mounting location is calculated. If the dynamic stiffness is too low, structural optimization is required. If the target value cannot be achieved due to layout or other reasons, the addition of rubber vibration isolation is considered. Finally, the subwoofer's operating excitation, obtained from the test, is applied to the subwoofer's mounting location on the vehicle body. The sound pressure responses of the driver and front passenger in the vehicle are calculated and compared with the target values ​​for feedback, thereby satisfying design requirements.

Description

Technical Field

[0001] The present invention relates to the field of automobile manufacturing, and in particular to a method for controlling abnormal vibration and noise of an automobile subwoofer. Background Art

[0002] With the increasing number of car owners in my country, car audio modification has become a symbol of improving drivers' lives. Many people enjoy listening to music while driving. Therefore, the quality of music has a significant impact on the customer's subjective experience. Subwoofers have high output power, strong bass impact, and powerful bass transients, making them suitable for audiophiles who enjoy singing, DJing, and rock music. Therefore, many OEMs directly include subwoofers in their car development to enhance the competitiveness of their vehicles.

[0003] Compared to regular car speakers, subwoofers offer greater power and a deeper, deeper bass. However, improper pre-design matching, such as improper mounting locations or poor mounting rigidity, can easily lead to unwanted noise from subwoofer excitation. This is especially true after a car has been used for a while, as various performance factors degrade. Many cars on the market experience these noise issues after-sales repairs, increasing repair costs and severely impacting the brand's reputation. Therefore, it's crucial to manage unwanted subwoofer noise during vehicle development.

[0004] As people's living standards improve, the popularity of cars is increasing. This leads to higher expectations for vehicles. Currently, numerous vibration control theories, such as vibration isolation and transfer functions, are available to address NVH (Non-Volatile, Harsh) vibration issues. Through various design and optimization methods, automotive noise and vibration can be effectively controlled. The primary source of noise from car subwoofers is the excitation of the subwoofer itself, which is amplified by its mounting location. Summary of the Invention

[0005] In view of the above problems, the present invention can positively guide the installation of the subwoofer and the design and development of the local structure of the vehicle body by controlling the resonant abnormal sound produced by the subwoofer.

[0006] The specific technical solutions are as follows:

[0007] A method for controlling vibration and abnormal noise of a car subwoofer comprises the following steps:

[0008] 1) Model Preparation: Build a finite element model of the vehicle body with trim. The model includes the body-in-white, interior acoustic cavity, closure components, interior and exterior trim, and various accessories mounted on the body. Fluid-structure coupling processing is required between the interior acoustic cavity, the body, and closure components.

[0009] 2) Select the subwoofer installation location:

[0010] 3) Subwoofer installation location selection: Calculate the dynamic stiffness of the subwoofer installation point. If the dynamic stiffness is too low, reselect the location or optimize the structure design;

[0011] 4) Subwoofer vehicle resonance and noise analysis: Based on the subwoofer excitation measured on the test bench, it is applied to the subwoofer body mounting position, and the noise and vibration response inside the vehicle is calculated and compared with the target.

[0012] Furthermore, in step 2), the subwoofer installation point is selected at a position with strong rigidity, such as a crossbeam or longitudinal beam, and it is avoided to be installed on a large thin-walled surface (such as the floor or rear panel).

[0013] Furthermore, in step 3), the dynamic stiffness is calculated using the finite element method and dynamics-related theories, and the dynamic expression is:

[0014]

[0015] [M] represents the mass matrix; [C] represents the damping matrix; [K] represents the stiffness matrix; {F} represents the external load vector matrix; represents the node acceleration; Nodal velocity; {u} represents the nodal displacement vector; (t) represents the load action time;

[0016] The steps for establishing the finite element model of the vehicle body with decoration include:

[0017] (1) Import the geometric model of the body with decoration and perform mesh division;

[0018] (2) Define the grid cell type;

[0019] (3) Define the material properties and density of the mesh elements; ensure that the model quality is consistent with the actual quality;

[0020] (4) Define the properties of the unit, solid, shell, etc.

[0021] Furthermore, in step 3), if the installation point dynamic stiffness is low due to layout or other reasons, it is necessary to add rubber vibration isolation pads to reduce the vibration transmitted from the subwoofer to the vehicle.

[0022] By studying subwoofer excitation and response, this paper comprehensively explains how to control subwoofer resonance and the resulting abnormal noise. It also proposes a method for controlling the resonant noise caused by subwoofer excitation. A finite element model of the vehicle body is established. The dynamic stiffness of the subwoofer installation location is first calculated. If the dynamic stiffness is too low, structural optimization is required. If optimization to the target value is impossible due to layout or other reasons, the addition of rubber vibration isolation is considered. Finally, the subwoofer excitation obtained during operation is applied to the subwoofer installation location on the vehicle body. The sound pressure response of the driver and front passenger is calculated and compared with the target value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flowchart of the subwoofer vibration and abnormal noise control method of the present invention;

[0024] Figure 2 The finite element model established in Example 1;

[0025] Figure 3 Calculation results of the subwoofer vibration and abnormal noise in Example 1. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] 1) Model preparation. Establish a finite element model of the body with decoration. The model includes the body in white, the interior sound cavity, closure parts, interior and exterior decoration and various accessories installed on the body. The interior sound cavity and the body and closure parts need to be processed by fluid-solid coupling. The established model is as follows: Figure 2 shown.

[0028] 2) Subwoofer installation location selection: The subwoofer installation location selection is critical. It is recommended to select a location with strong rigidity, such as a crossbeam or longitudinal beam, and try to avoid installing it on a large thin-walled surface (such as the floor or rear panel).

[0029] 3) Subwoofer Mounting Location Selection: Calculate the dynamic stiffness of the subwoofer mounting point. If the stiffness is too low, reselect the location or optimize the structural design. If the mounting point has low dynamic stiffness due to layout or other reasons, add rubber vibration isolation pads to reduce vibration transmitted from the subwoofer to the vehicle interior.

[0030] The calculation of dynamic stiffness requires the use of finite element method and dynamics related theory. The dynamic expression is:

[0031]

[0032] [M] represents the mass matrix; [C] represents the damping matrix; [K] represents the stiffness matrix; {F} represents the external load vector matrix; represents the node acceleration; Nodal velocity; {u} represents the nodal displacement vector; (t) represents the load action time.

[0033] The steps to establish the finite element model of the body with decoration include:

[0034] (1) Import the geometric model of the body with decoration and perform mesh division;

[0035] (2) Define the grid cell type;

[0036] (3) Define the material properties and density of the mesh elements; ensure that the model quality is consistent with the actual quality;

[0037] (4) Define the properties of the unit, solid, shell, etc.

[0038] 4) Analysis of vehicle resonance and abnormal noise of subwoofer

[0039] The subwoofer excitation measured on the test bench is applied to the subwoofer's body mounting location, and the noise and vibration response inside the vehicle is calculated and compared with the target.

[0040] Example 1

[0041] The specific implementation method is described below using a certain PK model as an example.

[0042] 1. Analyze the type of software required

[0043] The finite element analysis software AltairNVHD is used for response analysis, and the pre-processing software is Hypermesh.

[0044] 2. Data Preparation

[0045] Collect the CAD geometric data of the vehicle body assembly (including interior and exterior trim, body accessories, etc.) as well as the material grade, weight data, and connection data (connection method) corresponding to each part.

[0046] 3 Establishing the finite element model

[0047] Based on the collected CAD geometry data, as well as the corresponding material, weight, and connection data, the decorated body is discretized according to finite element theory, and Hypermesh pre-processing software is used to perform mesh division and define unit attribute types and materials.

[0048] 3.1 Mesh the decorated vehicle body.

[0049] 3.2 Divide the decorated car body into grids and assign material properties. According to the material characteristics, input the corresponding material properties.

[0050] 3.3 Definition of boundary conditions and working conditions

[0051] The subwoofer excitation is derived from actual bench testing;

[0052] The excitation position is the actual installation position of the subwoofer;

[0053] The body structure and the acoustic cavity inside the vehicle need to set the fluid-solid coupling parameters. After setting, submit the calculation. The final calculated results are as follows Figure 3 .

[0054] The above describes in detail the preferred embodiments of this patent, but this patent is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the purpose of this patent.

Claims

1. A method for controlling vibration and abnormal noise of a car subwoofer, characterized by: The steps include: 1) Model Preparation: Build a finite element model of the vehicle body with trim. The model includes the body-in-white, interior acoustic cavity, closure components, interior and exterior trim, and various accessories mounted on the body. Fluid-structure coupling processing is required between the interior acoustic cavity, the body, and closure components. The steps for establishing the finite element model of the decorated car body include: (1) importing the decorated car body geometry model and meshing it; (2) defining the mesh element type; (3) defining the material properties and density of the mesh elements; ensuring that the model quality is consistent with the actual quality; (4) defining the element properties, solid and shell; 2) Select the subwoofer installation location: 3) Subwoofer installation location selection: Calculate the dynamic stiffness of the subwoofer installation point. If the dynamic stiffness is too low, reselect the location or optimize the structure. The dynamic stiffness calculation uses the finite element method and related dynamics theory. The dynamic expression is: [M] represents the mass matrix; [C] represents the damping matrix; [K] represents the stiffness matrix; {F} represents the external load vector matrix; represents the node acceleration; Nodal velocity; {u} represents the nodal displacement vector; (t) represents the load action time; 4) Subwoofer vehicle resonance and noise analysis: Based on the subwoofer excitation measured on the test bench, it is applied to the subwoofer body mounting position, and the noise and vibration response inside the vehicle is calculated and compared with the target.

2. The method for controlling vibration and abnormal noise of a car subwoofer according to claim 1, characterized in that: Step 2) Select a location with strong rigidity for the subwoofer installation point.

3. The method for controlling vibration and abnormal noise of a car subwoofer according to claim 1, characterized in that: In step 3), if the installation point dynamic stiffness is low due to layout or other reasons, add rubber vibration isolation pads to reduce the vibration transmitted from the subwoofer to the car.

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