Study Of Dynamic Characteristics Of Hydraulic Mount

The hydraulic engine mount is a bidirectional vibration isolation element between the powertrain and the frame,and its dynamic characteristics affect the vibration isolation performance of the mounting system,which is related to the NVH performance of the vehicle.However,the dynamic characteristics of the hydraulic mount are highly sensitive to excitation amplitude.If the dynamic characteristics of the hydraulic mount can be accurately predicted,it can be beneficial to the design of the hydraulic mount.In addition,there is the possibility of decoupler’s impact noise in the hydraulic engine mount.This paper will study the simulation and experiment of the dynamic characteristics of the hydraulic mount,prediction and experiment of the decoupler’s impact noise.The main works are shown as follows:1)Based on the structure of the hydraulic mount,the nonlinear lumped parameter model of the hydraulic mount is established.And then the differential equations of motion of hydraulic mount are deduced,and the mathematical model of the hydraulic mount is obtained.2)Through material experiments,the parameters of the hyperelastic constitutive model and the viscoelastic constitutive model of the rubber are identified.The parameter identification method of the lumped parameter model is proposed.Through finite element analysis and fluid mechanics formulas,the lumped parameters of the hydraulic mount are calculated,such as the dynamic stiffness and the loss angle of the main rubber,the equivalent piston area,the volumetric compliance of the upper chamber,the liquid inertia and resistance of the flow channel,and the contact force between the decoupler and the cage.3)Using the lumped parameter model and the results of the parameter identification,the dynamic characteristics of the hydraulic mount are simulated.Through the bench test,the static and dynamic characteristics of the hydraulic mount are measured.The simulation results are compared with the test results to verify the accuracy and reliability of the lumped parameter model and parameter identification method.The influence of the parameters of the hydraulic mount on the dynamic characteristics is analyzed.The trend of the influence of each parameter on the dynamic characteristics of the hydraulic mount is obtained,which is convenient for adjusting the dynamic characteristics of the hydraulic mount during the development stage.4)The generating mechanism of the abnormal noise of the hydraulic mount is illustrated,and the method of avoiding the impact noise of the decoupler is analyzed.Taking three hydraulic mounts as an example,the contact stiffness between the decoupler and the cage of the hydraulic mounts is calculated,and the contact stiffness is used to determine whether the hydraulic mount will generate abnormal noise.A bench test of abnormal noise of hydraulic mount is designed,and the impact noise of the decoupler of the hydraulic mount is evaluated by the sound pressure signal.The relationship between the reaction force at the fixed end of the hydraulic mount and the impact force of the decoupler is deduced,and a method is proposed to determine whether the hydraulic mount will generate the decoupler impact noise based on the reaction force signal.According to the results of the simulation and experiment,the structural design experience of the decoupler and the cage is summarized.The research can guide the development and optimization of the hydraulic mount,and it is valuable in engineering applications.