Method for testing the natural frequency of a rearview mirror

Abstract

The present application relates to the technical field of automobile rearview mirror, and discloses a rearview mirror natural frequency test method, comprising the following steps: installing the rearview mirror on a three comprehensive vibration test bench to generate a natural frequency conclusion curve; installing the rearview mirror on an actual vehicle to test the natural frequency of the actual vehicle and obtain the frequency value of the rearview mirror to be adjusted; installing the rearview mirror on the three comprehensive vibration test bench to record the frequency value with the maximum amplitude by using vibration optical performance test, and improving the rearview mirror according to the frequency value to be adjusted and the natural frequency conclusion curve; and installing the improved rearview mirror on the actual vehicle to complete final verification. The rearview mirror natural frequency test method can measure the natural frequency of the rearview mirror by combining the test of the actual vehicle and the test bench, and can test and verify the frequency improvement scheme by the test bench, so that the influence of the whole vehicle is avoided, and the solution to the rearview mirror vibration problem can be accurately and efficiently found.

Description

Technical Field

[0001] This invention relates to the field of automotive rearview mirror technology, specifically to a method for testing the natural frequency of a rearview mirror. Background Technology

[0002] The vibration performance of rearview mirrors is one of the important performance characteristics of automotive rearview mirrors. Among them, the natural frequency of the rearview mirror system is an important parameter of the vibration performance of the rearview mirror. When the natural frequency avoids the resonance frequency band of the whole vehicle, the rearview mirror can avoid the problem of shaking.

[0003] Currently, when dealing with the problem of rearview mirror vibration, the most common method for judging the condition, analyzing countermeasures, and confirming the effect is to use subjective evaluation. However, subjective evaluation is greatly affected by the overall condition of the vehicle. If the overall condition of the vehicle is poor, it is difficult to determine the root cause of the rearview mirror vibration problem. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a method for testing the natural frequency of a rearview mirror. By combining actual vehicle testing with test bench testing, the natural frequency of the rearview mirror can be measured, and frequency improvement schemes can be verified through test bench testing. This avoids the influence of the entire vehicle and accurately and efficiently finds solutions to the rearview mirror vibration problem.

[0005] To achieve the above objectives, the rearview mirror natural frequency testing method designed in this invention includes the following steps:

[0006] A) Before installation: Install the rearview mirror on the three-dimensional vibration test bench, conduct the natural frequency test on the three-dimensional vibration test bench, obtain the natural frequency of the rearview mirror on the three-dimensional vibration test bench, generate the natural frequency conclusion curve, and judge the reliability of the key structure of the rearview mirror.

[0007] B) Vehicle installation stage: Remove the rearview mirror and install it on the actual vehicle. Perform a test on the natural frequency of the actual vehicle to obtain the natural frequency of the rearview mirror on the actual vehicle. Compare it with the resonant frequency band of the entire vehicle to determine whether there is a risk of vibration of the rearview mirror on the actual vehicle. If there is a risk of vibration, the difference between the natural frequency of the rearview mirror on the actual vehicle and the upper or lower limit of the resonant frequency band of the entire vehicle is the frequency value that the rearview mirror needs to be adjusted.

[0008] C) Physical Improvement Stage: Remove the rearview mirror and reinstall it on the three-dimensional vibration test bench. Perform a frequency sweep test on the rearview mirror using vibration optical performance testing, and record the frequency value with the largest amplitude. Then, based on the frequency value that the rearview mirror needs to be adjusted obtained in step B), and combined with the natural frequency conclusion curve obtained in step A), perform physical improvement on the rearview mirror. Increase or decrease the natural frequency of the rearview mirror by strengthening or weakening the rigidity of key structures. Then, perform a frequency sweep test on the rearview mirror again using vibration optical performance testing, and record the frequency value with the largest amplitude. Compare this with the frequency value with the largest amplitude obtained before physical improvement. If the difference is greater than or equal to the frequency value that the rearview mirror needs to be adjusted, the physical improvement is considered effective; otherwise, continue with physical improvement.

[0009] D) Verification phase: The improved rearview mirror is reinstalled on the actual vehicle, and the natural frequency of the rearview mirror on the actual vehicle is tested to obtain the natural frequency of the rearview mirror on the actual vehicle, thus completing the final verification.

[0010] Preferably, when performing natural frequency testing on the three-integration test bench, the test parameters are as follows:

[0011] Test equipment: Three-dimensional vibration test bench;

[0012] The natural frequency of the rearview mirror fixture is >100Hz;

[0013] Sensor placement: A total of 3 data acquisition points, respectively attached to the center of the primary mirror surface, the midpoint of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting points on the base:

[0014] Point of impact: Before the rounded corner at the lower end of the telescope shaft;

[0015] Striking tool: Sensing force hammer;

[0016] Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function;

[0017] Transfer function curve: The first peak corresponds to the first mode of the hindsight mirror in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in units of a / F.

[0018] Preferably, when conducting the natural frequency test of a real vehicle, the test parameters are as follows:

[0019] Sensor placement: There are a total of 3 data acquisition points, which are respectively attached to the center of the main mirror surface, the middle point of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting point on the base;

[0020] Point of impact: Before the rounded corner at the lower end of the telescope shaft;

[0021] Striking tool: Sensing force hammer;

[0022] Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function;

[0023] Transfer function curve: The first peak corresponds to the first mode of this assembly component in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in a / F.

[0024] Preferably, the test parameters for conducting vibration optical performance tests are as follows:

[0025] Acceleration: 0.2g / 0.5g;

[0026] Frequency band sweep: 10Hz~50Hz;

[0027] The laser source is 400mm from the mirror and reflects the light perpendicularly onto the projection board at a 45° angle. The projection board is 2000mm from the mirror.

[0028] Frequency sweep and recording: 0.2g acceleration: sweep frequency and record the frequency value with the largest amplitude; 0.5g acceleration: sweep frequency and record the frequency value with the largest amplitude, and record the specific size of the amplitude for each frequency value.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. By establishing and applying the test system for the natural frequency of the rearview mirror system, the analysis of the vibration performance of the rearview mirror has achieved the following effects: predicting vibration performance, directly addressing the root cause of vibration problems, analyzing countermeasures and verification without being limited by the whole vehicle, and effectively avoiding repeated verification.

[0031] 2. Provide more comprehensive testing methods for rearview mirror vibration performance during the design and development of the rearview mirror system, reduce the impact of actual vehicles on the analysis, countermeasures and verification of rearview mirror vibration performance, shorten the cycle of vibration problem analysis, countermeasures and verification, and ensure vehicle performance and quality. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments.

[0033] A method for testing the natural frequency of a rearview mirror includes the following steps:

[0034] A) Before installation: Install the rearview mirror on the three-dimensional vibration test bench, conduct the natural frequency test on the three-dimensional vibration test bench, obtain the natural frequency of the rearview mirror on the three-dimensional vibration test bench, generate the natural frequency conclusion curve, and judge the reliability of the key structure of the rearview mirror.

[0035] B) Vehicle installation stage: Remove the rearview mirror and install it on the actual vehicle. Perform a test on the natural frequency of the actual vehicle to obtain the natural frequency of the rearview mirror on the actual vehicle. Compare it with the resonant frequency band of the entire vehicle to determine whether there is a risk of vibration of the rearview mirror on the actual vehicle. If there is a risk of vibration, the difference between the natural frequency of the rearview mirror on the actual vehicle and the upper or lower limit of the resonant frequency band of the entire vehicle is the frequency value that the rearview mirror needs to be adjusted.

[0036] C) Physical Improvement Stage: Remove the rearview mirror and reinstall it on the three-dimensional vibration test bench. Perform a frequency sweep test on the rearview mirror using vibration optical performance testing, and record the frequency value with the largest amplitude. Then, based on the frequency value that the rearview mirror needs to be adjusted obtained in step B), and combined with the natural frequency conclusion curve obtained in step A), perform physical improvement on the rearview mirror. Increase or decrease the natural frequency of the rearview mirror by strengthening or weakening the rigidity of key structures. Then, perform a frequency sweep test on the rearview mirror again using vibration optical performance testing, and record the frequency value with the largest amplitude. Compare this with the frequency value with the largest amplitude obtained before physical improvement. If the difference is greater than or equal to the frequency value that the rearview mirror needs to be adjusted, the physical improvement is considered effective; otherwise, continue with physical improvement.

[0037] D) Verification phase: The improved rearview mirror is reinstalled on the actual vehicle, and the natural frequency of the rearview mirror on the actual vehicle is tested to obtain the natural frequency of the rearview mirror on the actual vehicle, thus completing the final verification.

[0038] The test parameters for the natural frequency test of the three-dimensional integrated test bench are as follows:

[0039] Test equipment: Three-dimensional vibration test bench;

[0040] The natural frequency of the rearview mirror fixture is >100Hz;

[0041] Sensor placement: A total of 3 data acquisition points, respectively attached to the center of the primary mirror surface, the midpoint of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting points on the base:

[0042] Point of impact: Before the rounded corner at the lower end of the telescope shaft;

[0043] Striking tool: Sensing force hammer;

[0044] Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function;

[0045] Transfer function curve: The first peak corresponds to the first mode of the hindsight mirror in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in units of a / F.

[0046] The test parameters for conducting the natural frequency test on a real vehicle are as follows:

[0047] Sensor placement: There are a total of 3 data acquisition points, which are respectively attached to the center of the main mirror surface, the middle point of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting point on the base;

[0048] Point of impact: Before the rounded corner at the lower end of the telescope shaft;

[0049] Striking tool: Sensing force hammer;

[0050] Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function;

[0051] Transfer function curve: The first peak corresponds to the first mode of this assembly component in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in a / F.

[0052] The test parameters for vibration optical performance testing are as follows:

[0053] Acceleration: 0.2g / 0.5g;

[0054] Frequency band sweep: 10Hz~50Hz;

[0055] The laser source is 400mm from the mirror and reflects the light perpendicularly onto the projection board at a 45° angle. The projection board is 2000mm from the mirror.

[0056] Frequency sweep and recording: 0.2g acceleration: sweep frequency and record the frequency value with the largest amplitude; 0.5g acceleration: sweep frequency and record the frequency value with the largest amplitude, and record the specific size of the amplitude for each frequency value.

[0057] In the above embodiments, the natural frequency of the rearview mirror is confirmed by using a three-dimensional test bench. This eliminates the influence of sheet metal mounting points and door sheet metal structures, yielding the natural frequency of the rearview mirror itself. The result is used to guide design improvements before vehicle installation. Since there are no sheet metal influencing factors, this conclusion is generally higher than the natural frequency measured on an actual vehicle. Therefore, the vertical axis (acceleration a / F under unit force) of this natural frequency conclusion curve is generally used to make a preliminary judgment on the reliability of key structures of the rearview mirror.

[0058] During real-vehicle natural frequency testing, if the engine's first-order frequency at idle is 30Hz, then the natural frequency of the rearview mirror measured on the real vehicle must avoid 27-33Hz. This can determine whether the rearview mirror has a risk of idling vibration on this model. This method can also be used to accurately find the cause of the rearview mirror when idling vibration occurs, whether it is due to the natural frequency not avoiding the resonance band and resonating with the whole vehicle, and at the same time determine whether the frequency needs to be increased or decreased to avoid the resonance band.

[0059] This invention provides a rearview mirror natural frequency testing method. By establishing and applying a rearview mirror system natural frequency testing framework, it achieves the following effects in analyzing rearview mirror vibration performance: predicting vibration performance, directly addressing the root cause of vibration problems, analyzing countermeasures and verification without being limited by the whole vehicle, and effectively avoiding repeated verification. It also provides a more comprehensive rearview mirror vibration performance testing method during the design and development of rearview mirror systems, reducing the impact of actual vehicles on the analysis, countermeasures, and verification of rearview mirror vibration performance, shortening the cycle of vibration problem analysis, countermeasures, and verification, and ensuring vehicle performance and quality.

Claims

1. A method for testing the natural frequency of a rearview mirror, characterized in that: Includes the following steps: A) Before installation: Install the rearview mirror on the three-dimensional vibration test bench, conduct the natural frequency test on the three-dimensional vibration test bench, obtain the natural frequency of the rearview mirror on the three-dimensional vibration test bench, generate the natural frequency conclusion curve, and judge the reliability of the key structure of the rearview mirror. B) Vehicle installation stage: Remove the rearview mirror and install it on the actual vehicle. Perform a test on the natural frequency of the actual vehicle to obtain the natural frequency of the rearview mirror on the actual vehicle. Compare it with the resonant frequency band of the entire vehicle to determine whether there is a risk of vibration of the rearview mirror on the actual vehicle. If there is a risk of vibration, the difference between the natural frequency of the rearview mirror on the actual vehicle and the upper or lower limit of the resonant frequency band of the entire vehicle is the frequency value that the rearview mirror needs to be adjusted. C) Physical Improvement Stage: Remove the rearview mirror and reinstall it on the three-dimensional vibration test bench. Perform a frequency sweep test on the rearview mirror using vibration optical performance testing, and record the frequency value with the largest amplitude. Then, based on the frequency value that the rearview mirror needs to be adjusted obtained in step B), and combined with the natural frequency conclusion curve obtained in step A), perform physical improvement on the rearview mirror. Increase or decrease the natural frequency of the rearview mirror by strengthening or weakening the rigidity of key structures. Then, perform a frequency sweep test on the rearview mirror again using vibration optical performance testing, and record the frequency value with the largest amplitude. Compare this with the frequency value with the largest amplitude obtained before physical improvement. If the difference is greater than or equal to the frequency value that the rearview mirror needs to be adjusted, the physical improvement is considered effective; otherwise, continue with physical improvement. D) Verification phase: The improved rearview mirror is reinstalled on the actual vehicle, and the natural frequency of the rearview mirror on the actual vehicle is tested to obtain the natural frequency of the rearview mirror on the actual vehicle, thus completing the final verification.

2. The method for testing the natural frequency of a rearview mirror as described in claim 1, characterized in that: When performing natural frequency testing on the three-integration test bench, the test parameters are as follows: Test equipment: Three-dimensional vibration test bench; The natural frequency of the rearview mirror fixture is >100Hz; Sensor placement: A total of 3 data acquisition points, respectively attached to the center of the primary mirror surface, the midpoint of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting points on the base: Point of impact: Before the rounded corner at the lower end of the telescope shaft; Striking tool: Sensing force hammer; Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function; Transfer function curve: The first peak corresponds to the first mode of the hindsight mirror in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in units of a / F.

3. The method for testing the natural frequency of a rearview mirror as described in claim 1, characterized in that: The test parameters for conducting the natural frequency test on a real vehicle are as follows: Sensor placement: There are a total of 3 data acquisition points, which are respectively attached to the center of the main mirror surface, the middle point of the vertical section of the mirror rod or the front of the rounded corner of the upper horizontal section, and the middle position of the 2PC mounting point on the base; Point of impact: Before the rounded corner at the lower end of the telescope shaft; Striking tool: Sensing force hammer; Impact method: Simulate the impact direction of the hammer in the X, Y, and Z directions to obtain the three-dimensional FRF transfer function; Transfer function curve: The first peak corresponds to the first mode of this assembly component in that direction (X / Y / Z) on the horizontal axis, and the vertical axis is the acceleration under unit force, in a / F.

4. The method for testing the natural frequency of a rearview mirror as described in claim 1, characterized in that: The test parameters for vibration optical performance testing are as follows: Acceleration: 0.2g / 0.5g; Frequency band sweep: 10Hz~50Hz; The laser source is 400mm from the mirror and reflects the light perpendicularly onto the projection board at a 45° angle. The projection board is 2000mm from the mirror. Frequency sweep and recording: 0.2g acceleration: sweep frequency and record the frequency value with the largest amplitude; 0.5g acceleration: sweep frequency, record the frequency value with the largest amplitude, and record the specific size of the amplitude for each frequency value.