NVH Analysis And Improvement Design Of Vehicle Engine Mounting System

The engine mounting system is an important subsystem of the automobile, so its characteristic of transmitting vibration has very great influence on automobile comfortableness. If choosing suitable parameters of the engine mounting system, it can reduce the automobile’s vibration and noise level and improve the automobile’s NVH. At the same time, it can also guarantee safe and reliable when engine is working, and avoid becoming damage too early of the engine part and accessories.Regarding improving the automobile’s NVH as start point, this text puts the engine mounting system as the research object and analyses characteristic of noise and vibration. At the end, this text gets the purpose to optimize and improve designing to the engine mounting system. The main research contents are asfollows:(1) Testing and diagnosing the car NVH performance preliminarily. Taking a local auto as the research object, the engine mounting system is the real reason leading the sound’s quality to be worse, at the same time, the common technological procedure to test and diagnose the car NVH performance is set up.(2) The vibration analysis and improvement designing to the engine mounting system. It puts optimization to mounting system for the background, sets up corresponding CAE and analyzed models at first, and examines the degree of reliance through energy solves coupling. Then takes the minimum of the sum of against force as implementing the goal function; through the sensitivity analysis, confirms the rigidity of six directions as the variable of designing, thus set up optimization design model and draw the result of optimizing. Finally, analyses a lot of operating modes and weighing, then gets out of the implement the project improved suggestion to the engine mounting system.(3) The acoustics analysis and improvement designing to the engine mounting system. Regarding the engine mounting system as a substructure (subsystem) appended on the car body, an explicit formula about the quantitative relationship between the sound pressure of interior noise and some of the engine mounting system characteristic parameters of a vehicle, is deduced based on the dynamic substructure modification method for structure-acoustic coupling analysis of an automobile’s passenger compartment. In order to improve computational efficiency and reduce the requisition for soft hardware environment of the computer, it gets the quantitative relation by using the technology of response surface. Then sets up the acoustics optimization design model, the result is valuable for improving the auto’s NVH. At the same time, it verifies the exactness of the preliminary conclusion tested and diagnosed by further.In the course of above-mentioned research, we obtained certain theory and technological innovation, as follows:(1) The common technological procedure is set up to test and diagnose the car NVH performance. it offers the effective technological solution for solving the actual project problem.(2) An explicit formula about the quantitative relationship between the sound pressure of interior noise and some of the engine mounting system characteristic parameters of a vehicle is deduced based on the dynamic substructure modification method for structure-acoustic coupling analysis of an automobile’s passenger compartment. It established the foundation for acoustics optimization design to the engine mounting system.(3) In order to improve computational efficiency and reduce the requisition for soft and hardware environment of the computer, the response surface technology is introduced to get response surface approximate relationship between the sound pressure of interior noise and some of the engine mounting system characteristic parameters of a vehicle.