A SUV Intake Acceleration Noise Analysis And Control Research

Vehicle interior noise affects the passenger occupant comfort, and the hearing maybe be damaged by a vehicle interior noise for long. As the source of vehicle interior noise is diverse and the noise control is complex, the problem of controlling the vehicle interior noise has become a major difficulty for vehicle manufacturers. Along with the automobile exhaust muffler, engine elastic support, mechanical mechanism and other noise reduction measures are widely used, also the engine speed and the intensive degree rise, the influence of intake system noise to interior noise is increasingly coming to light, and becomes the main noise sources of vehicle interior noise. Therefore, the reasonable structure of the intake system is the most effective and simple way to reduce the vehicle noise.How to design a reasonable structure of the intake system to control the noise is the key issue of vehicle interior noise control.The method of theory calculation, computer simulation, experiment analysis and verification, is used for researching the vehicle interior noise in this article.According to research, we can get the design and engineering method for air cleaner and t resonator.By reducing the intake noise, we can reduce the vehicle interior noise to achieve the objective. The main research results are as follows:First, it analyzes the noise of intake systems of source, generation and identification method. Noise control work is first to master the noise source and producing, select the right noise identification method to identify the noise characteristic. According to the generation principle,the intake noise can be divided into cyclical pressure pulse noise, pipeline resonance noise, cylinder Helmholz resonance noise and current noise. The noise source is a wide frequency range noise from low frequency to high frequency. As intake pipe of air speed increases together with the increase of engine speed, the intake noise is increasing rapidly. Therefore, the intake system must be designed which can reduce a relatively wide frequency of noise.And because the noise identification must get the relationship of engine speed with intake noise, we can not use the traditional noise identification methods, including spectrum analysis method.So the order tracking analysis method will be used as it can be satisfied this requirement.Second, using the theoretic calculation combining with computer simulation, determine the air intake filter design. Based on the expansion muffler principle, according to theoretical calculation, combination with the engine layout, we can get three schemes of the intake air cleaner.By computer simulation software of acoustic boundary element method ( Acoustic, BEM, ABEM ) and acoustic finite element method ( Acoustic, FEM, AFEM ),we can get the acoustic performance simulation of the three models,that the?possibility of three schemes coupled resonance between shell structure mode and cavity acoustic mode is very low. For each order, all schemes can reduce the noise in acoustic modal frequencies for all orders. According to the transmission loss result with or without filter paper, the schemeⅢis the best, which the insertion tube is longer, tube diameter of inlet and outlet is thinner, at higher flow rates or more thick filter on the air filter has better silencing effect.so that the air filter in the frequency band are good acoustic attenuation performance. By simulation and calculation results, the final selection schemeⅢis the final design plan. Using computational fluid dynamics simulation(CFD), the schemeⅢof fluid dynamics simulation results show that, the air cleaner on the engine load range has good flow characteristics, maximum differential pressure is about 2.4kPa at maximum flow rate 540m3/h, which less than the general engineering requirement, the maximum allowable differential pressure 3kPa.Third, identify the inlet noise characteristics after air cleaner by order analysis and auxiliary silencer test method. According to the Ford engineering test specification CETP:03.12-1-L401, the real vehicle test was done in semi anechoic laboratory within the drum, using the LMS Test. Lab software to collect the air intake and the interior noise data. By the analysis, the test results show that 68Hz, 141Hz, 203Hz, 302Hz, 361Hz, 450-480Hz of the order present obvious peak of noise. The frequency of the noise at the air intake is is closely related to the car interior noise. According to the air inlet noise frequency analysis and retrofitting of absolute muffler comparison test, it should be design the muffler of 68Hz, 140Hz, 304Hz, 470Hz to reduce the influence of frequency noise, improving linearity and enhancing comfort under certain speed.Fourth, base on the principle of noise elimination of Helmholtz resonator intake system optimization, we design the resonance frequency of 68Hz, 140Hz, 304Hz, 470Hz resonant cavity, and do the work frequencies test one by one. Comparing the vehicle interior noise test results between original state and different frequency resonant cavity, we can found that the vehicle interior noise decreased the 3-5dB ( A ) at about 68Hz resonant cavity and about 2000RPM, but at 68Hz with other frequency resonant cavity, the noise reduction effect without obvious changes, and in addition to about 2000RPM noise inside the vehicle to have the same degree of lower speed range, other noise without significant changes. Therefore, that is the reason that 68Hz resonator can reduce the noise to contol the 2 order intake noise.After finishing the engineering design and producting prototype of 68Hz resonator, we do the comparison test equipt the prototype. The test results show that the target has been reached the design requirement.This research object of this paper is a new vehicle of Jiangling Motor Co., LTD, which studied the identification and control in the intake noise. Base on the intake system, we research the intake acceleration noise analysis and control, using CAE simulation and test methods to design and optimize the air intake system, and finally reduce the intake noise in order to achieve the purpose of control of vehicle interior noise. This paper presents the design, simulation and test combination noise analysis and control method for vehicle, domestic enterprises NVH design has a good reference value.