Simulation And Experiment Study For The Dynamic Characteristics Of A Semi-active Control Hydraulic Mount

Comfort is the main performance index for automobile,especially forcar.There are two vibration resources in automobile,one is the road surfacerandom exciting while running;the other one is vibration of engine whileworking.In a general way,the first one has great influences on the passenger,butwith the improvement of road conditions and the consummate of the suspensionsystem designing,the influences in this aspect are lowered to a certain degree;onthe other hand,the design of modern car emphasized on lowering theweight,adopting new-type,high-strength,light-nature materials in order to lowerthe mass of the whole vehicle,but it is too hard to lower the weight ofengine,thus the vibration exciting of the engine on the bodywork increasescomparatively and becomes the main vibration resource of car.So it is a keyproblem for automobile designing to isolate the vibration transmitted from theengine to the bodywork. The vehicle engine mounting system usually consists of an engine andseveral mounts connected to the vehicle structure.The result of study indicate,thecharacteristic of the vibration isolation has great influence to the comfort.Theengine mounting system with excellent performance may isolate the vibrationtransmitted from the engine to the bodywork,reduce the noise in the cab,improvethe ride comfort and protect the engine. There are six parts in this dissertation as following: Based on large amount of internal and external thesis, chapter one introducethe background and history of the development of vehicle engine mountingsystem;advance design requirement and ideal specification of mount；gather upthe representative structures of different type mount have been introduced, list the 69Abstractadvantage and disadvantage of different type mount. Chapter two analyze the configuration and working principle of a semi-activecontrol hydraulic mount adopted by some native car,set up its mechanicsmodel.The working principle is:two separate chambers are conneted with eachother by an inertia track and an orifice.The control method is controlling ON-OFFof the orifice.The upside of orifice communicate with the upper chamber all thetime,whereas there are a kinetic valve between its underside and the buttonchamber.There are a pore connected with engine in the downside of the kineticvalve.In the natural working state,the orifice is closed by the valve and the fluidflow only by the inertia track. On the idle speed,the orifice is opened and the fluidflow by orifice mostly.It is benefitable for attenuate the vibration on idle speedbecause the damping and the dynamic stiffness are devalued. Chapter three summarize the history and background of bondgraph;introduce its theory foundation and principle; set up the bond graph modelof a semi-active control hydraulic mount and detrude the state equation of themount system,establish research and simulation foundation for mount systemdynamic characteristics adopting bond graph. The experiment method,principle and content of the experiment of hydraulicmount dynamic characteristics are introduced briefly in chapter four.From theoutcome of experiment we can see that the dynamic characteristics of the mountsystem is improved effectively by using semi-active control.In low frequencyscale, especially on the frequency of idle speed,the dynamic characteristics ofmount system can be adjusted and controlled.The dynamic characteristics ofmount can meet the demand of ideality dynamic characteristics of mountsystem,thus the vibration of engine can be attenuated rapidly on idle speed andcomfort is improved. Chapter five firstly introduce the criterion of appraise vibration isolation;give 70吉林大学硕士学位论文the method,formula and program of accounting every parameter. Simulation andcomputation of mount dynamic characteristics are done by Matlab/Simulink...