Study On Engine Support Dynamics And Vibration Isolation

Engine support system refers to the elastic system that supports the engine.Generally refers to the elastic connection system between the engine and its components on the vehicle and the frame,as well as the elastic connection system between the engine and the test bench in the laboratory.The engine support system is generally connected with the frame or bench through the suspension element,so it can also be called the engine suspension system.The engine support system can isolate engine vibration and restrain engine vibration.With software development as the ultimate goal,the fuzzy and unclear problems in the model and calculation are studied to support the design and optimization services.Firstly,the vibration excitation source of the engine is analyzed in this paper,and the two excitation forces which have the greatest influence on the system,the reciprocating inertia force of a single cylinder and the overturning moment are calculated in detail.In order to increase the calculation range of overturning moment of the system under different rotational speeds,three kinds of interpolation algorithms are proposed,which are neighborhood interpolation algorithm,triangle interpolation algorithm and bilinear interpolation algorithm respectively.Secondly,the single cylinder incentive force is extended to multi-cylinder engines,and the expression of the generalized force of multi-cylinder engines is written,which lays a foundation for the generalization of software development.In the selection of degrees of freedom,the coordinate system with the origin at the intersection of the center line of the crankshaft and the rear end face of the first cylinder block is selected,which is different from the commonly used three coordinate systems with the origin at the center of mass.And for the commonly used three kinds of coordinates between the inertial parameters of the transformation between the strict description and the transformation tool development.Then the kinetic energy,potential energy and dissipated energy of the engine support system are calculated in the selected modeling coordinate system,and the mass matrix,stiffness matrix and damping matrix are obtained.Finally,the equations of mass matrix,stiffness matrix,damping matrix and generalized force array are substituted into the equation of Lagrange.Then the dynamic calculation and analysis of the engine support system are carried out,and the natural frequency and mode of the engine support system are obtained by using the free vibration calculation method of jorisky decomposition method and Jacobi method.Based on the results of free vibration calculation,the energy distribution and stability validity calculation methods of the system are presented.Then,the forced vibration calculation method of the deformable mode superposition method and the harmonic response calculation method is adopted for the engine support system.Then,the dynamic algorithm was programmed for the engine support system,and an engine vibration calculation software was developed with visual studio.This software can calculate the vibration of the engine support system composed of different number of cylinders,different strokes,different engine types,and different number of supports.The mechanical model of a certain engine support system is built in ADAMS to verify the software algorithm.Finally aiming at a certain engine support system vibration isolation effect is not ideal,considering the limitation of design and production costs,to support suspension rubber components as design variables,the three main vibration decoupling degree as the objective function,an improved particle swarm-tabu search optimization algorithm,the optimization of the engine support system,the optimized engine support system the main direction of the decoupling rate was improved.This paper also discusses the influence of strut parameters,and presents an equivalent treatment model of strut stiffness,which can accurately reflect the influence of strut stiffness on engine vibration.