Analysis on Hanger Location and Hanger Isolator of an Exhaust System with Powertrain

Abstract

To improving the NVH (Noise, Vibration and Harshness) performance of vehicles, the NVH performance of exhaust system must be considered. As hanger is the main vibration transfer path and hanger isolator is the crucial vibration isolation components, it is necessary to study hanger location and stiffness of vibration isolation. About the study of exhaust system is executed in four steps. Firstly, according the free modal analysis of the exhaust system, the ADDOFD (Average Driving Degree of Freedom Displacement) is acquired, and the suitable location of hanger is confirmed soon. Secondly, studied the powertrain influences to the vibration performance of exhaust system, the constrained modal frequencies must avoid the engine idle resonant frequency. Thirdly, the dynamic analysis of the exhaust system is researched based on the second step, in which way 100000N·mm sinusoidal excitation is applied at the powertrain’s barycenter in the crankshaft rotation direction, and then the response reaction force (less than 5N) of the hanger are gained. Finally, the relationship between the bending and torsional modes of exhaust system and the stiffness of the hanger isolator are inquired. It is of great engineering significance. Keywords-NVH; ADDOFD; resonant frequency; reaction force; exhaust system