Study On Vehicle Interior Noise Reduction

With the fast developing of the automotive industry, the customers are becoming less tolerant of unwanted noise and vibrations. Vehicle interior noise is one of the key factors. Combined with project of local car manufacturer, the vehicle interior noise reduction and control are discussed.Firstly, conducted the evaluation of the car's noise performance and benchmarking, defined the object. According to spectrum analysis and order analysis, the property of the interior noise is obtained. Then the vibro-acoustic analysis of total car is analyzed via experimental modal analysis of the car body in white and experiment of the transfer loss performance of different component of the car. The improvement methods include adding sealing, damping and sound-absorbing materials and optimization of the engine mount system.Secondly, in the experiment method for transfer loss, TMP method was used to get the transfer loss according to present standing wave tube method. Measurement of acoustic sensitivity is used to evaluate the damping effects on the car body.Finally, Design optimization of a 4-cylinder 4-stroke engine-mount system for vibration control is presented in this paper. The total force transmitted from the engine to the floor is minimized by choosing the stiffness of each mount. The SQP (Sequential Quadratic Programming) method is used as the optimization algorithm. The static and dynamic deflections are also kept within the desired limits. Compared with the original system, the force transmission is only half. The mechanism of vibration isolation is investigated with the frequency response of the system.