Design On Parameter Of Hydraulic Engine Mount

Comfort is the main performance index for automobile, especially for car. There are two vibration resources in automobile, one is the road surface random exciting while running; the other one is vibration of engine while working. In a general way, the first one has great influences on the passenger, but with the improvement of road conditions and the consummate of the suspension system designing, the influences in this aspect are lowered to a certain degree; on the other hand, the design of modern car emphasized on lowering the weight, adopting new-type, high-strength, light-nature materials in order to lower the mass of the whole vehicle, but it is too hard to lower the weight of engine, thus the vibration exciting of the engine on the bodywork increases comparatively and becomes the main vibration resource of car. So it is a key problem for automobile designing to isolate the vibration transmitted from the engine to the bodywork.The vehicle engine mounting system usually consists of an engine and several mounts connected to the vehicle structure. The result of study indicate that the characteristic of the vibration isolation has great influence to the comfort. The engine mounting system with excellent performance may isolate the vibration transmitted from the engine to the bodywork, reduce the noise in the cab, improvethe ride comfort and protect the engine. There are five parts in this dissertation as following: Based on large amount of internal and external thesis, chapter one introduce the background and history of the development of vehicle engine mounting system; advance design requirement and ideal specification of mount;gather up the representative structures of different type mount have been introduced, list the advantage and disadvantage of different type mount.Chapter two analyze the configuration and working principle of a hydraulic mount adopted by some native car, set up its mechanics model. Then set up mathematical model base on hydrodynamics and mechanics model.Chapter three firstly introduce the criterion of appraise vibration isolation; give the method,formula and program of accounting every parameter. Simulation and computation of mount dynamic characteristics are done by Matlab/Simulink. From the outcome of simulation we can see that the dynamic characteristics of the mount system is improved effectively by using hydraulic mount. But, there are some tolerances in simulation: The causation is simulation for the characteristics of fluid flow exist error with the course of real working. For example the simulation for inertia track take into the concentrative mass of inertia track account, but neglect the coupling action of the fluid with rubber. So there is some limit when the model of this dissertation is used to simulate or forecast the mount dynamic characteristics in high frequency.Then in chapter four , contrast the outcome of simulation and analyze the infection of AP,L,A f, and so on. From the contrast we can see that there are many factors influence the dynamic characteristics of the mount system, The dynamic stiffness of Hydraulic Engine Mount is influenced by rubber spring and hydraulic absorber machine. Hydraulic absorber machine-a most factor- infulances the damping of Hydraulic Engine Mount . The dynamic characteristics of mount can meet the demand of ideality dynamic characteristics of mount system,thus the vibration of engine can be attenuated rapidly on idle speed and comfort is improved.Chapter five is a summary of this dissertation and prospect of this research.