Research On Improvement Analysis And Application Of Engine Cabin Sound Insulation Structure Based On Sound Quality Evaluation

With the improvement of people’s living standards,people are paying more and more attention to the level of noise in the car.Nowadays,with the rapid improvement of technology,there are more and more ways to reduce vehicle interior noise.According to the ways of noise reduction,active noise reduction and passive noise reduction can be divided.As an important sound insulation structure between engine cabin and passenger cabin,the acoustic performance of the front panel is the key factors of the vehicle interior noise,including the sound absorption level of the acoustic package attached to the panel,which plays a significant role in the overall noise level of the vehicle.The traditional sound pressure level evaluation has been unable to meet the requirements of people’s evaluation of vehicle interior noise.Therefore,the evaluation of sound quality for vehicle interior noise level has become the current trend.Aiming at the problem of vehicle interior noise caused by the middle and high frequency excitation sound of powertrain through the sound insulation structure of the front panel,the following research is done on the front panel and the acoustic package attached panel.First of all,in this paper,the front panel between the engine cabin and the passenger cabin of a domestic passenger car are studied.Through the analysis of the structure characteristics of the front panel,the subsystem is divided reasonably and the SEA model is established;combining the theoretical analysis and the test method to obtain the relevant parameters of the SEA model,and compare the test and simulation data to determine the accuracy of the SEA model.According to the simulation of the influence factors of acoustic package on front panel like cover,tone thickness and leakage.Then,the conclusion that the influence of the structure and acoustic parameters of the front panel having an impact on its sound insulation character in the range of 400Hz-8000 Hz frequency is obtained.Under the condition that the overall structure and material properties of the acoustic package of the front plate are unchanged,exploring the design method of optimizing the acoustic package,so as to achieve the goal of sound insulation and noise reduction of acoustic package on front panel.Secondly,based on the SEA model,we set up the FE-SEA model.By analyzing the influence of mesh size,subsystem split and material of the hole,we choose the best modeling scheme combined with the experimental result to ensure the accuracy of the model.After that,according to simulating and analyzing the influence of damping on the sound insulation performance of the front panel in the range of 100Hz-1000 Hz frequency,the conclusion of the damping applied to the key position of the front panel which is much better than the large area plus damping and the method of applying the position of damping is put forward.According to the above analysis,damping is applied to improve the sound insulation level of the front panel in practical engineering,and the result of damping is verified through the experiment of air sound transfer function.Finally,based on the above analysis conclusion,the acoustic package and damping are used to optimize the sound insulation structure of the front panel of the car,And optimize the other ways to influence the interior noise of the car,then,making and evaluation of internal sound quality before and after improvement by objective sound quality evaluation parameters,The results show that the optimization of the front panel has made an important contribution to the improvement of the internal sound quality of the vehicle.