Analysis And Control Of Vehicle Cab Interior Noise Based On Excitation Of Power-train

Excitation of power-train is one of the main sources of vehicle interior noise and vibration. Most of vehicle interior noise caused by power-train excitation through mounts of body is low frequency, while, most of vehicle interior noise caused by power-train excitation through sound wave is high frequency. Low frequency noise can be controlled by modifying body structure and high frequency noise can be controlled by damping and sound-absorbing material.The main purpose of this paper is to study how to utilize CAE methods in vihicle NVH design, and to control vehicle interior low frequency and high frequency noise combining the characteristic of power-train excitation. At the mean time, this paper also studies how to control noise by test method. The main contents of this paper are as follows:1. Vehicle interior low frequency (20~200Hz) noise excited by power-train system was analyzed and controlled by using finite element analysis (FEA). Through vehicle interior noise calculation, it is found that the noise close to driver’s ears exceeded the design objectives at the peak of 125Hz.The rear windshield is the panel which makes the biggest contribution to the noise through panel contribution analysis. At last, top girder of the rear windshield was modified for the optimization. Validation analysis showed that the method used to control vehicle interior low frequency noise was effective.2. Statistical energy analysis (SEA) was done to control vehicle interior high frequency (200-5000Hz) noise excited by power-train system. Through analysis, the noise near driver’s ears was found to exceed the design objectives and its value is between 600 to 1000Hz. Through input energy analysis of driver’s head and leg cavity, it is found that front doors make the biggest contribution to vehicle interior high frequency noise. Finally, damping and sound-absorbing materials are added to the front doors according to analysis results. Validation analysis showed that the method used to control vehicle interior high frequency noise was effective.3.Experimental transfer path analysis (TPA) was employed to control vehicle interior noise excited by the power-train system in this article. Firstly, the transfer path analysis model which was from the passive side of engine mount to the driver’s ear was established. Then, the Z-left mount was found the main source of the vehicle interior noise by TPA. The reason why this path contributes remarkably is the bad transfer rather than the larger excitation. Finally, the left mounting bracket was strengthened according to the analysis results. Validation analysis showed that the method used to control vehicle interior noise was effective.The research shows that from low frequency to high frequency ranges, from CAE to test and from theory to practice, this paper gave a fully solution in vehicle NVH design based on the power-train excitation.