The Optimizing Technology Study Of Engine Mount System

The disturbance from engine and road is two causes of vehicle vibration, the engine mount system plays an important role in isolating vibration. firstly, it must isolate the transfer of vibration from engine to body, secondly, it must isolate the body vibration caused by road from engine-mount system. The performance of engine mount system has much effect on NVH performance of car, so the mount system design is always a hot topic in vehicle design. At present, there are two main methods to design mount system, one is the traditional method-- modal decouple, which control the system response by changing the stiffness matrix to change system modes; the other one controls the force transfer between the engine and body by optimizing the parameters of mounts with dynamic response as objective directly. With the two methods, design optimization of engine mount system of a national FF car is studied in this paper. The following content is included:1. The mathematic model of engine mount system that is used to decouple modes is built, the disturbance frequencies are analyzed and engine mount system mode frequencies are proper arranged. With energy mode decouple theory, the modes of engine mount system are decoupled.2. The parameterized dynamic model of rubber mount and hydro-mount are set up, which can simulate the frequency dependency characteristics and amplitude dependency characteristics of rubber mount and hydro-mount. The engine disturbances calculated through dynamic formulation and dynamic model in ADAMS/view are compared. The dynamic model of engine mount system is built in ADAMS/view, with the dynamic parameters, positions and directions of mount as variables, with the sum of weighted force responses at mounts as objective, the design optimization is implemented.3. Flex body and rigid-flex coupled dynamic model of car are built, with the velocity RMS of key points on car as evaluation, the vibration isolation performance of decouple engine mount system and dynamic optimized engine mount system is reviewed, and the final result of mount parameters are fixed.4. For transverse engine and three- point-layout engine mount system, engine mount system optimization program is programmed, and the help document is work out. The program can implement mode decouple optimization and dynamic response optimization.