Design Method Of Sporty Sound Quality Of Vehicle Exhaust Noise Based On Order Analysis

The sound characteristics of the car is the embodiment of car quality,image and brand personality,and it is an important indicator that directly reflects the quality of car products and affects the psychology of customers.Different types of vehicles have different sound quality characteristics due to different requirements.Therefore,corresponding sound design needs to be implemented according to different functions,styles and differences between vehicle conditions and driving conditions.Creating their own sound quality characteristics of the vehicle is the main development direction of vehicle NVH(Noise,Vibration and Harshness)under the premise of meeting the needs of different customers for different sounds.Exhaust noise is one of the main noise sources of automobile noise,and its sound design is also an important task of car sound design.In this paper,in order to achieve the design target of sporty exhaust noise,the order target determination of sporty exhaust sound quality,the research on the correlation of acoustic performance and structural parameters of the exhaust system and the achievement of the sporty exhaust sound quality based on structural improvement were studied by the methods of modeling,simulation and experiment.And a design method of the sporty sound quality of the vehicle exhaust noise based on order analysis was proposed.Firstly,the paper proposed an order noise control target for the sound quality of exhaust noise.The original exhaust noise characteristic was analyzed through the objective test and subjective evaluation of the exhaust noise of the research vehicle.The order sound pressure level of the exhaust noise under rapid acceleration condition was adjustmented and the order noise was compounded by using the self-developed order sound modulation software,and then about 600 sound samples were formed.Through the subjective evaluation test,the sound samples satisfying the order target of sporty sound quality were determined,the order bistribution of which samples was analyzed,and then the order target of sporty sound quality was obtained.Four benchmark passenger vehicles those have typical sporty sound quality and no sporty sound quality respectively were selected,and their exhaust noise under accelerating condition were objectively tested to judge whether the order noise components were satisfied the determined order target range of the sporty exhaust sound quality,and the subjective evalution results proved the validity of this order target.According to this order target,it was possible to accurately and intuitively judge whether a sound had sporty sound quality from objective test results,and effectively determine the main engine speeds and characteristic frequencies those caused the sound quality that did not satisfy the sporty sense.It could provide accurate direction guidance for the design of exhaust system improvement.Secondly,the paper clarified the correlation and regularity of the structural parameters and acoustic performance of resistant muffler.On the base of the three-dimensional finite element acoustic theory,the numerical calculation method of acoustic mode and transmission loss of the closed-type resistant muffler cavity structure were analyzed.The research program on the acoustic performance of the structure of the resistant muffler was developed,and then the Virtual.lab and GT-Power software were used respectively to simulate and analyze the acoustic mode and transmission loss of the developed research program.Through the regularity study,the correlation between the structural parameters of the resistant muffler and the acoustic performance,and the correlation between the acoustic mode frequency and mode sharp and transmission loss were obtained.The conclusion qualitatively clarified the acoustic performance of the structural parameters of the resistant muffler on different frequencies and acoustic modes,and provided a theoretical basis for the design of sound quality.Finally,a method for obtaining the sporty sound quality of exhaust noise based on the structure design of the muffler was established.By establishing a one-dimensional engine working simulation model and exhaust noise coupling analysis model,the prediction model of exhaust order noise was obtained.According to the conclusion of the relationship between the structural parameters of the muffler and the acoustic performance,combined with the orthogonal test method and the sensitivity analysis of the structural parameters,the structural parameters of the muffler with the greatest influence on the exhaust order noise were determined.Through reasonable parameter design,the designed schemes which satisfied the order target of sporty sound quality were obtained.The exhaust noise objective test of actual vehicle acceleration and the on-site subjective evaluation test were carried out in the vehicle NVH semi-anechoic chamber.The test results verified that the designed exhaust muffler schemes could realized sporty exhaust sound quality,which also proved the effectiveness of the designed schemes.