Hanger Location Design And Research Of The Vibration Isolation Of A Passager Car Exhaust System

With the increasing of the retained vehicles, the exhaust gas and noise pollute the environment where people are living. In the components of vehicle, the engines is the main cause of noise and exhaust gas.Therefore, the exhaust system is important for the control work of noise and exhaust gas which are transferred from the engine. When the vehicle is running, the exhaust system vibrates because of the frequent load from the engine. Thereby, the vibration has an impact on the fatigue durability and reliability of the structures and isolators. At the same time, the vibration may be transferred to the body through the hangers and isolators, and the NVH level will decrease. So, it's necessary to study and optimize the vibration of the exhause system.Modal analysis can help to get the mode shape and frequency and give the theroy basis of vibration analysis and fault diagnosis as well as some optimizing work.Modal analysis can be divided to two kinds---the test modal analysis and numerical modal anslysis. This paper uses both the test modal analysis and numerical modal anslysis to study the exhaust system. Using the modal analysis, the modal frequency and shape of the exhaust system can be got. Then it can be known whether the modal frequecy is kept from the engine idle speed exciting frequency.In this paper, based on the exhaust system of a passenger car, with softwares---Hypermesh and ANSYS, FEA modal of the exhaust system is completed, firstly. Especially, the different FEA models of the muffler are compared, and this paper chooses the models closed to actual structures. The modal test result is closed to the simulation data, so this way to build the FEA model of the muffles is reasonable ADDOFD is used to design and adjust the hanger locations, From the result of the static analysis, modal analysis and dynamic analysis, the force of the hangers is more average; the modal frequency is kept from the engine idle speed exciting frequency; the force transferred to body by isolator is reduced.In the last part of this paper, Orthogonal design is used into the isolator dynamic sftiffness optimizing,and the result indicate this idea is effective and the vibration isolation of the rubber isolator system is improved.Finally the way to analyze the exhaust vibration performance is helpful for engineering project. However, the idea of designing hanger location and optimizing the isolator dynamic stiffness can be used to guide the design and modify of the exhaust system in the beginning period of vehicle development.