Noise Test Of An Engine And Research On Noise Reduction Of Key Components

In recent years,with the strengthening of people’s demand for vehicle comfort and environmental awareness,the customer’s requirements for vehicle sound quality become higher and higher.More and more attention has been has paid to the vehicle noise and vibration,and the requirements for vehicle noise and vibration between different countries and industries have become more and more strict.How to better understand the engine’s noise and how to reduce the noise of the engine become the problem that each noise team must face.This dissertation systematically introduces the mechanism of engine noise,noise classification,manifestation and control methods.The engine NVH development process is established,and the engine development is carried out based on the process.The scope of subjective evaluation is expanded.The ten point subjective evaluation system is put on the bench to identify and optimize the problems affecting the sound quality in advance.The acoustic characteristics of exhaust manifold heat shield are studied,the effectiveness of sandwich material with damping layer in solving resonance coupling noise of exhaust heat shield is verified.The noise reduction method of generator is introduced,and its effectiveness is verified in engineering.The mechanism of oil pump noise is studied,and the problem of oil pump pulsation noise is solved by simulation technology.The method of adjustment of intake system is improved,making the adjustment of the engine intake system be advanced to the engine bench verification stage,and the problems related to the engine intake that could only be found in the whole vehicle stage were discovered in advance and optimized and rectified,shortening the cycle of the development of the whole vehicle intake system.The multi-dimension calibration of the intake system model improves the accuracy of the analysis results and provides a solution to solve the intake system noise problem digitally.This dissertation introduces the application of acoustic package in engine noise reduction,which greatly reduces the engine sound pressure level and expands the means of engine noise reduction.Through a series of noise optimization,the engine noise level in all directions is reduced,and improve the sound quality.The results show that the method of engine noise analysis and optimization established and perfected in this paper has good engineering practical value.