Study On Dynamic Characteristic Model And Optimization Of Powertrain Mounting

Powertrain mounting,which has the function of fixing and damping vibration of powertrain, is an elastic member connecting the frame and the powertrain. According to requirements of powertrain mounting system, the mount is needed to reflect performances when it is hit by large amplitude single at low frequency,it has large stiffness and damping character to damp the vibration causing by uneven road surface,and when it is hit by small amplitude single at high frequency, it has small stiffness and damping character to isolate the powertrain vibration under normal operating condition. Hydraulic engine mounts is the most widely used elastic element currently,and with deepening research on the dynamic characteristics of hydraulic engine mount, the damping performance has also been a huge increasing on NVH.In this paper, it carried out to establish the model, to identify the main parameters,analysis and optimization of dynamic characteristics parameters based on direct throttle hydraulic engine mount. It also revealed the isolation theory of hydraulic engine mounts and the influence of the main component to its dynamic characteristics.In addition, through the multi-objective optimization of hydraulic engine mount, get more ideal design parameters in order to lay a foundation for the design and development of the same kinds of mounts. The main contents follows:1 、 According to the requirements of vibration isolation of powertrain mounting system, established lumped parameter model under two kinds of resistance excitation,and Nonlinear characters of internal fluid, flowing through the relevant components were analyzed.2、The main rubber springs and direct-complete throttle hydraulic engine mount were tested to research dynamic characteristics based on the direct throttle hydraulic engine mount,with dynamic stiffness and the lag angle as the characteristic evaluation indicators of hydraulic engine mounts. It contains the influence of different excitation amplitudes and frequencies at the different excitation solution rubber engine mounts to the dynamic characteristics of the main spring and complete hydraulic engine mount. In addition,it shows dynamic characters in different conditions of hydraulic engine mounts,which provides evidence for the optimization of parameters and a reverse researching method of hydraulic engine mount.3、After the establishment of three-dimensional finite element model, it verified the accuracy of the simulation by comparing dynamic simulation curve obtained by liquid-solid coupling finite element analysis and experiments; In order to study the accuracy of the model parameters and establish a correspondence between the physical model parameters between models to provide the basis for subsequent optimization, use finite element method to identify parameters of mount to provide the basis for further optimization and reverse research by comparing with theoretical calculations of lumped parameter model.4、According to lumped parameter model,make the stiffness and damping of main rubber spring elements, the volume fluid chamber stiffness of the throttle in the lumen,the length and cross-sectional area of Inertia channel and others of hydraulic engine mount as design variables, and make the peak of dynamic stiffness and damping element, frequency value at the dynamic stiffness and damping reaching the peak,constant value of dynamic stiffness and damping of hydraulic engine mount when the frequency approaches infinity as the optimization target to carry out multi-objective optimization by the use of genetic algorithms. Compared with original value, compared to the original value, the optimized damping performance meets the isolation needed better of mounting system by the reverse research of Liquid- Solid Coupled Finite Element Analysis.