A new energy vehicle exhaust system structure noise testing device

Abstract

The utility model belongs to the field of car, concretely relates to a new energy vehicle exhaust system structure noise test and objective evaluation device. Noise testing device includes data acquisition system, vibration sensor, microphone, force hammer, test platform and shielded cable connection line, noise objective evaluation device, including data processing unit, matrix operation unit, sound pressure superposition unit and evaluation unit. The utility model has the advantages of simple test equipment, wider test range, more robust test data and more real test results.

Description

Technical Field

[0001] This utility model belongs to the automotive field, specifically relating to a device for testing and objectively evaluating the exhaust system structure noise of new energy vehicle models. Background Technology

[0002] The current assessment of exhaust system structural noise in new energy vehicles relies on lug dynamic stiffness testing (requiring an MTS elastomer testing machine) and synchronous measurement of active / passive end displacement. The process is cumbersome, the equipment cost is high, and there are the following limitations: (1) It can only test the Z-axis vibration component and ignores the X / Y-axis vibration contribution; (2) Due to equipment limitations, the effective test frequency is limited to 250Hz, and mid-to-high frequency noise cannot be assessed; (3) The test data is greatly affected by temperature and vehicle body vibration, and the error accumulation is significant.

[0003] The complex exhaust system of new energy vehicles (as shown in Figure 1) is caused by battery layout. Hook vibration is transmitted to the vehicle body in the XYZ three-dimensional direction, causing mid-to-high frequency resonance and booming sounds inside the vehicle. Traditional methods indirectly calculate structural noise based on the noise transfer function (NTF) and hook force F, requiring simultaneous measurement of dynamic stiffness and displacement data, which has significant limitations (see patent CN201510123456.7 "Vibration Test Method for Automobile Exhaust System"). Excitation force calculation: This is achieved through the dynamic stiffness k of the hook lug and the displacement difference (ΔX) between the active and passive ends. The dynamic stiffness needs to be tested using an MTS elastomer testing machine, and displacement data needs to be obtained through a vibration testing device. Transfer function test: The sound transfer function from the exhaust system to the vehicle interior is measured using a hammer impact method.

[0004] Existing technical defects: (1) Lack of mid-to-high frequency noise calculation: Due to the limited accuracy of the MTS dynamic stiffness testing equipment, the dynamic stiffness K curve of the lifting lug can only obtain data below 250Hz, resulting in the calculation of structural noise only covering the low frequency band, and mid-to-high frequency noise above 250Hz cannot be evaluated. (2) Omission of directional components: Traditional dynamic stiffness testing can only obtain the Z-direction stiffness of the hook, while the exhaust system of new energy vehicles is complex and the X / Y direction vibration is significantly enhanced. Existing technology only calculates the Z-direction component and ignores the other two X and Y directions (accounting for 2 / 3 of the total), resulting in increased noise evaluation error. (3) Insufficient temperature adaptability: The dynamic stiffness of the lifting lug is sensitive to temperature changes, but the existing test only covers discrete temperature points from -10°C to 40°C, which cannot match the actual working conditions (such as the engine high temperature zone above 80°C), resulting in the force calculation results deviating from the true value. (4) Accumulation of measurement error: The active / passive end displacement test relies on the cantilever sensor, which is easily affected by the modal vibration amplification effect and the interference of the whole vehicle system. Multiple average corrections of errors are required, which is inefficient and difficult to guarantee accuracy. Utility Model Content

[0005] The purpose of this invention is to provide a device for testing and evaluating the structural noise of the exhaust system in new energy vehicles, which can more accurately and comprehensively test and evaluate the structural noise of the exhaust system, providing a reliable basis for the design optimization of the exhaust system.

[0006] A noise testing device for an exhaust system structure includes a data acquisition system, a vibration sensor, a microphone, a hammer, a testing platform, and a shielded cable connection. The data acquisition system stores time-domain waveform data in real time and transmits it to a data processing unit via the shielded cable (impedance ≤ 0.1 Ω). The vibration sensor is positioned near the hook in a location with high vehicle body rigidity and is fixed with bolts using a rigid bracket. The microphone is positioned inside the vehicle, near the driver's ear or in the passenger's position. The hammer is used to strike the exhaust system hook, with the striking point located at the center of the hook. The testing platform has a stiffness ≥ 100 N / mm². 2 An insulated platform; the vibration sensor, microphone, and hammer are all connected to the data acquisition system via shielded cables, with interface impedance matching ≤0.1 Ω. Signal transmission path: Vibration sensor → Data acquisition system → Data processing unit; Hammer trigger signal → Data acquisition system → Matrix operation unit.

[0007] Furthermore, the data acquisition system employs an embedded processor with a built-in multi-channel signal conditioning module, supporting the synchronous acquisition of vibration acceleration, transfer function, and sound pressure signals from the vibration sensor (three-way) and microphone, with a sampling frequency covering 20 Hz to 1 kHz.

[0008] Furthermore, the vibration sensor is triaxial, and the vehicle body stiffness requirement for mounting it is ≥200 N / mm. 2 Two are arranged symmetrically.

[0009] Furthermore, the microphone has a measurement range of 40 dB(A) to 100 dB(A) with an accuracy of ±0.5 dB.

[0010] Furthermore, the impact error of the hammer is ≤ ±5 mm, the range is 0.1 N to 50 N, and the peak force resolution is 0.01 N.

[0011] Furthermore, the test platform is made of glass fiber reinforced epoxy resin, which is used to fix the data acquisition system on the vehicle to ensure the stability and accuracy of the test process.

[0012] Furthermore, this utility model also provides an objective evaluation device for the structural noise of an exhaust system, including a data processing unit, a matrix operation unit, a sound pressure superposition unit, and an evaluation unit. The data processing unit performs signal preprocessing through an embedded processor with a built-in low-pass filter (cutoff frequency 1kHz) to improve the accuracy and reliability of the data. The matrix operation unit calculates the forces acting on each hook in each direction of the exhaust system using mathematical methods such as the least squares method based on vibration data and vibration transfer function data. Based on the calculated force and noise transfer function data, the structural noise acting on each hook in each direction of the exhaust system is calculated using mathematical methods such as the least squares method. The sound pressure superposition unit calculates the total structural noise of the exhaust system according to the principle of sound source superposition. The evaluation unit objectively evaluates the structural noise of the exhaust system based on the calculated structural noise data and in conjunction with preset evaluation standards, providing guidance for the design optimization of the exhaust system.

[0013] This invention can obtain all the data required for the structural noise of new energy vehicle models using only this testing system (the noise transfer function NTF from each hook in each direction to the vehicle interior, the vibration transfer function to each reference point, and the vibration data of the reference point under the test conditions); Evaluation unit: This patent can evaluate the impact of the exhaust system structure on the interior of the vehicle by obtaining the equivalent structural noise and the actual test noise, providing strong support for subsequent vehicle problem investigation and new vehicle design.

[0014] The beneficial effects of this utility model are as follows: Simple testing equipment: No need for lug dynamic stiffness testing equipment; Wider testing range: There is no limitation on the frequency of the lug dynamic stiffness curve, and frequencies above 250Hz can be tested; More robust test data: By optimizing the sensor layout and algorithm, full-band (20Hz-500Hz), all-directional (XYZ three-way) and full-condition coverage is achieved, and the testing efficiency is improved by 40%; More realistic test results: Because all the data used in the calculation comes from the actual operating state of the whole vehicle, the results are more realistic. Attached Figure Description

[0015] Figure 1 Existing technology exhaust system structure diagram (XY plane) of a certain new energy vehicle;

[0016] Figure 2 Diagram of the exhaust system noise testing device of this utility model;

[0017] Figure 3 This utility model provides a schematic diagram of the vibration reference point installation.

[0018] Figure 4 Overall flowchart of this utility model;

[0019] Figure 5 Example of the effect. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] This embodiment provides an exhaust system structural noise testing device. For example... Figure 2 As shown.

[0022] The system includes a data acquisition system, vibration sensors, microphones, a force hammer, a test platform, and shielded cable connections. The data acquisition system stores time-domain waveform data in real time and transmits it to the data processing unit via a shielded cable (impedance ≤ 0.1 Ω). It employs an embedded processor (model: XYZ-2000) with a built-in multi-channel signal conditioning module, supporting simultaneous acquisition of vibration acceleration, transfer function, and sound pressure signals from the three-dimensional vibration sensor and microphone, with a sampling frequency covering 20 Hz to 1 kHz.

[0023] Vibration sensor placement: The vehicle body near each hook has high rigidity (rigidity ≥ 200 N / mm). 2 Two 3D vibration sensors (model: VIB-3D) are symmetrically arranged at locations such as horizontal and vertical beams, and fixed with bolts to rigid brackets (dimensions: 50mm×30mm×5mm, material: aluminum alloy). The bolt hole diameter is 5 mm, and the spacing error is ≤±2 mm. Figure 3 As shown, this is the vibration data used to measure the reference point.

[0024] Microphone placement: Inside the vehicle, at the driver's ear or passenger's position (±50 mm from the center of the seat), measuring range 40 dB(A) to 100 dB(A), accuracy ±0.5 dB. Used to measure in-vehicle noise data.

[0025] The hammer is used to strike the hook of the exhaust system. The striking point is located at the center of the hook. The error is ≤ ±5 mm. The range is 0.1 N to 50 N. The peak force resolution is 0.01 N.

[0026] The test platform has a stiffness ≥100 N / mm 2 An insulating platform, preferably made of glass fiber reinforced epoxy resin, is used to fix the data acquisition system to the vehicle, ensuring the stability and accuracy of the testing process.

[0027] Connection method and signal transmission: The vibration sensor, microphone, and hammer are all connected to the data acquisition system via shielded cables (model: SMA-5), with interface impedance matching ≤0.1 Ω. Signal transmission path: Vibration sensor → Data acquisition system → Data processing unit; Hammer trigger signal → Data acquisition system → Matrix operation unit.

[0028] An objective evaluation device for exhaust system structural noise includes a data processing unit, a matrix operation unit, a sound pressure superposition unit, and an evaluation unit.

[0029] The data processing unit performs signal preprocessing through a low-pass filter (cutoff frequency 1kHz) built into the embedded processor to improve the accuracy and reliability of the data.

[0030] The matrix operation unit calculates the forces acting on each hook of the exhaust system in each direction using mathematical methods such as the least squares method, based on vibration data and vibration transfer function data. Then, based on the calculated forces and noise transfer function data, it calculates the structural noise acting on each hook of the exhaust system in each direction using mathematical methods such as the least squares method.

[0031] The sound pressure superposition unit calculates the total structural noise of the exhaust system according to the principle of sound source superposition.

[0032] The evaluation unit objectively evaluates the structural noise of the exhaust system based on the calculated structural noise data and pre-set evaluation criteria, providing guidance for the design optimization of the exhaust system. For example... Figure 5 As shown: Actual measurements revealed a resonant booming noise issue around 40Hz inside the vehicle. This patent confirms that this frequency is due to a structural problem in the exhaust system, specifically caused by the X-axis of the second hanger in the exhaust system. Finally, by strengthening the X-axis structure of the second hanger in the exhaust system, the problem was resolved.

[0033] This invention can obtain all the data required for the structural noise of new energy vehicle models using only this testing system (the noise transfer function NTF from each hook in each direction to the vehicle interior, the vibration transfer function to each reference point, and the vibration data of the reference points under the test conditions); the reference points need to be placed where the hook stiffness is relatively high (stiffness ≥ 200 N / mm). 2The location of the hook (including but not limited to crossbeams, longitudinal beams, and the vehicle body near the hook) must be carefully considered, with at least two reference points required. Symmetry (25±5mm) must be maintained, and the installation location must avoid the vehicle body weld area. Signal preprocessing is achieved using a low-pass filter (cutoff frequency 1kHz) built into the embedded processor to improve data accuracy and reliability. The matrix operation unit, implemented using an FPGA chip (model: FPGA-X5), supports parallel computing for increased efficiency and employs the least squares method to calculate the force F in each direction for each hook. The calculated F and the measured NTF are used to obtain the structural noise in each direction for each hook. The sound pressure superposition unit uses the principle of sound source superposition to obtain the equivalent structural noise. The evaluation unit uses the obtained equivalent structural noise and actual test noise to evaluate the impact of the exhaust system structure on the vehicle interior, providing strong support for subsequent vehicle troubleshooting and new vehicle design.

[0034] The overall testing and evaluation process in this embodiment is as follows: Figure 4 As shown. Overall, it can: ① simplify the testing process by inversely calculating the excitation force through passive end vibration and vibration transfer function, avoiding reliance on the frequency and temperature limitations of dynamic stiffness testing; ② provide multi-directional coverage by introducing XYZ three-dimensional vibration transfer function and component force calculation to fully evaluate the three noise components of XYZ, adapting to the complex structure of new energy vehicles; ③ provide full-condition coverage by combining real-time condition correction of transfer function parameters to improve the calculation accuracy in multiple scenarios such as normal temperature / high temperature / low temperature, asphalt / cement road surface; ④ optimize error control by symmetrically arranging reference points near the hook with stiffness ≥200N / mm. 2 The position is adjusted to reduce cantilever effect interference, reduce random errors, and improve the signal-to-noise ratio of a single measurement.

[0035] The preferred embodiments of this patent have been described in detail above. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A device for testing the structural noise of an exhaust system, characterized in that: The noise testing device includes a data acquisition system, vibration sensors, microphones, a hammer, a testing platform, and shielded cable connections. The data acquisition system stores time-domain waveform data in real time and transmits it to the data processing unit via shielded cables. The vibration sensor is positioned near the hook in a location with high vehicle body rigidity and secured with rigid bracket bolts. The microphone is positioned near the driver's ear or in the passenger's position inside the vehicle. A hammer is used to strike the exhaust system hook, with the striking point located at the center of the hook. The test platform has a stiffness ≥100 N / mm². 2 An insulated platform; vibration sensors, microphones, and force hammers are all connected to the data acquisition system via shielded cables, with interface impedance matching ≤0.1 Ω.

2. The exhaust system structural noise testing device according to claim 1, characterized in that: The data acquisition system uses an embedded processor with a built-in multi-channel signal conditioning module, which supports the synchronous acquisition of vibration acceleration, transfer function and sound pressure signals from vibration sensors and microphones, with a sampling frequency covering 20 Hz to 1 kHz.

3. The exhaust system structural noise testing device according to claim 1, characterized in that: The vibration sensor is a triaxial vibration sensor, and the vehicle body stiffness requirement for its installation is ≥200 N / mm. 2 Two are arranged symmetrically.

4. The exhaust system structural noise testing device according to claim 1, characterized in that: The microphone has a measurement range of 40 dB(A) to 100 dB(A) with an accuracy of ±0.5 dB.

5. The exhaust system structural noise testing device according to claim 1, characterized in that: The impact error of the hammer is ≤ ±5 mm, the range is 0.1 N to 50 N, and the peak force resolution is 0.01 N.

6. The exhaust system structural noise testing device according to claim 1, characterized in that: The test platform is made of glass fiber reinforced epoxy resin, which is used to fix the data acquisition system on the vehicle to ensure the stability and accuracy of the test process.

Images