Research on analysis and control method of interio

2022-07-26
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Research on the analysis and control method of automobile interior noise Abstract: through the diagnosis and analysis of the interior noise of a new car, it is confirmed that the car has serious resonance noise when the engine speed is 3700r/min, and the whole noise transmission path is deeply and carefully analyzed. Three improvement measures are proposed and tested respectively. After the three improvement measures are comprehensively adopted, The noise inside the vehicle is reduced by 3dB (a)

key words: noise order resonance vibration isolation

1 introduction

with the rapid development of automobile noise research, the noise target has been set higher and higher. The ideal noise control target should be a noise that is easy to accept, not boring after a long time, fully meets the requirements of customers and has a sense of power. Therefore, although the noise performance of automobile is not the basic performance of automobile, it is the quality index of automobile. With the further understanding of automobile, automobile noise will determine the sales status of automobile and dominate the automobile market. The noise performance of automobile has undoubtedly become a very important automobile quality index

when evaluating the noise perception of the car, it is found that the noise loudness of the car increases significantly at 3700r/min. If the noise lasts for a long time, it will make people feel irritable and very uncomfortable. Thus, the technical content of the car will be doubted. Therefore, how to solve the noise problem at 3700r/min has become an important problem to improve the vehicle

2 analysis of vehicle interior noise test

2.1 analysis of vehicle interior noise test of speed tracking

as engine noise plays a decisive role in vehicle noise, the change of vehicle noise with engine load can be seen by speed tracking noise test, which can also find out the change of vehicle noise at a certain order (based on engine speed), Further confirm the relationship between the excitation frequency of the noise excitation source and the engine speed. Now, the speed tracking noise test is carried out for the vehicle. The test results are shown in Figure 1. It can be seen that there is a large peak in the vehicle noise at 3700r/min, which is consistent with the sensory evaluation results. Moreover, the excitation of this peak is the second-order excitation of the engine, and the resonance noise frequency is 125Hz

Fig. 1 the car interior noise speed tracking order spectral matrix

2.2 speed tracking vibration test

now the query method is used to conduct vibration tests on the parts of the car that may cause this noise frequency, and the vibration test results of the bottom guard are shown in Fig. 2. The vibration of the bottom guard shown in Fig. 2 is consistent with the test results of the car interior noise, that is, there is resonance at 3700r/min. The bottom guard was removed for noise comparison test. The test results are shown in Figure 3. After the bottom guard was removed, the noise within 40000 tons has decreased by about 3.5 dB (a) by 1986. Therefore, the resonance noise in the vehicle at 3700r/min is mainly caused by the resonance of the bottom guard under the second-order excitation of the engine

Fig. 2 vibration order diagram of original bottom guard plate

Fig. 3 comparison results of four gear vehicle interior noise with and without bottom guard plate

3 noise transmission path analysis

from the structural characteristics of the vehicle, it can be preliminarily judged that the resonant noise transmission path in the vehicle at 3700r/min is shown in Fig. 4

Figure 4 noise transmission path figure

now the fifth engine mount is removed for the vehicle noise comparison test. The results are shown in Figure 5, and the results are reduced by about 2dB (a). It can be seen that the excitation is mainly transmitted from the fifth suspension to the bottom guard plate

Fig. 5 third gear interior noise acceleration test with or without fifth suspension rubber pad

4 improvement measures

1) change the material of the bottom guard to remove the resonance frequency. SMC material is used to replace the steel plate bottom guard. The comparison of the noise in the car is shown in Figure 6. Therefore, SMC material reduces the noise in the car of non recruited patients by 1.3db (a)

Figure 6 comparison results of interior noise of SMC material and steel plate bottom guard

2) reduce the excitation to the bottom guard, add rubber pads between the cross beam and the bottom guard, and use vibration isolation to reduce the excitation. The comparison results of interior noise are shown in Figure 7. Therefore, the method of reducing the excitation to the bottom guard reduces the interior noise by 2dB (a)

Figure 7 comparison results of interior noise before and after weakening the excitation to the bottom guard

3) vibration isolation method is adopted between the bottom guard and the subframe, and rubber pads are added to reduce the vibration transmitted into the body. The comparison results of interior noise are shown in Figure 8. Therefore, vibration isolation method is adopted for the bottom guard and the subframe to reduce the interior noise by 2dB (a)

figure 8 comparison results of interior noise after vibration isolation of bottom guard and subframe

in conclusion, the comparison results of interior noise after all the above three measures are adopted are shown in Figure 9, which reduces the interior noise of the vehicle by 3dB (a), and the visible effect is extremely obvious

Figure 9 comparison results of vehicle interior noise when all soft connections are used

5 conclusion

for vehicle interior noise test, if each component can be analyzed and measured in detail according to the methods described in this paper, and if some other auxiliary methods such as finite element method and noise simulation software can be combined, some effective test experience can be summarized, and useful databases can be accumulated, so as to reduce vehicle interior noise step by step, To improve the noise quality inside the vehicle, our noise design and operation software will fully meet the needs of customers and the market

references

1 heavy ultrasound Noise control engineering of electromechanical equipment Beijing: Light Industry Press, 1989, heyusheng Automobile noise control Beijing: China Machine Press, 1995

3 suzukls, t &kayaba, F. the analysis and mechanism of engine intake assembling noise, sae901755

4 Kuroda o &fujil y its working principle is that the servo system controls the electromechanical system (1988) Approach to Improve Engine Sound Quality, SAE880083(end)

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