Vibration Characteristic Analysis Of Coupled Manifold Of Engine

The exhaust purification of the vehicle is one of the important measures to control engine exhaust discharging. In order to meet the requirements of Euro IV emission standard, the catalytic converter is installed at the exit of exchaust manifold usually, that means the tight coupled manifolds are developed and used. Compared with the traditional arrangement, this structure could make the catalyst combust rapidly and full use of the catalyst efficiency, which is used widely in the Euro IV emission standard vehicle.This paper has established the three-dimensional models of tight coupled manifold and exhaust system, and the Finite Element Method and software ANSYS are employed to analyze their vibration problems. Firstly, the tight coupled manifold is investigated as a single part to analyze its natural vibration characteristics. In view of the characteristics of heated manifold by exhaust gas, the indirect method is used to calculate the thermal stress of exhaust manifold and the influence on the modes of the manifold. Secondly, the vibration situation of the whole exhaust system with the tight coupled manifold as the research object is analyzed, and the entire exchaust system vibration modes and the response are obtained under unit displacement. The vibration excited by exhaust gas is investigated also, which includes mainly the tight coupled manifold and the part of exhaust system with strong vibration. At last, regarding the problems discovered from vibration analysis of exhaust system, the optimum designs are conducted by redesigning the hanging of exchaust system, adjusting vibration isolator stiffness and installing dynamic vibration absorber.