Analysis And Research On Exciting Force Of Mechanical Noise In Internal Combustion Engine Caused By The Secondary Motion Of The Piston Basing On The Experiment

The noise of internal combustion engine can be divided into mechanical noise andcombustion noise and aerodynamic noise according to the generation mechanism. The pistonslap to the liner is the largest source of mechanical noise in the internal combustion engine,which is caused by the secondary motion of the piston. To these problems, simulation of thesecondary motion of the piston, in this paper, vibration response of the piston slapping andregularity of the sensitive parameters in piston slap force have been researched in thefoundation of kinematics and dynamics of the crank-connecting rod mechanism in this paper.Some progress has been made in terms of technical access to piston slap force and regularityof the sensitive parameters. More accurate and complete information of the exciting forceswill be provided for the analysis on the noise and vibration of powertrain in internalcombustion engine ultimately.With a four-stroke gasoline engine as the object of the research, the finite element modelof the piston has been established and the radial stiffness of the piston has been calculated byusing Hypermesh that is a finite element software, which can be used as the boundaryconditions of the dynamics simulation on the piston secondary motion; On the basis ofprevious research on the piston temperature field, the temperature field and thermaldeformation of the piston in the course of work have been calculated by using Workbench thatis a finite element software, and superimpose with the cold profile of the piston to obtain thethermal profile, which can be used as the boundary conditions of the simulation on contactstate of piston to cylinder.On the basis of relevant boundary conditions, the model that is the piston slapping to cylinder has been established in the multi-body dynamics analysis software-EXCITE,including the piston cylinder liner, connecting rod, piston pin, and piston rings. Piston slapmotion has been calculated combined with structural parameters and working conditions ofthe engine. The characteristics of the dynamics the secondary motion of the piston and contactload of the piston to cylinder have been obtained. Focusing on the researchment ofcharacteristics of piston slapping force. By comparing with quasi-static piston side forcecalculated by theoretical calculations, the characteristics of the dynamic slapping force in timedomain have been obtained, and the relevant characteristics of these different piston forces infrequency domain have been analyzed by fast flourier transform.On the basis of the above study, force vibration response based on the mode has beencalculated in the foundation of the finite element model of the powertrain.The piston slappingforce obtained by simulation has been loaded in the finite element model of thepowertrain,also with the other relative exciting forces. The vibration response of the surfacenode that is on both the thrust side and anti-thrust side of the liner have been obtainedrespectively by using the software LMS virtual. Lab. The vibration of the corresponding nodeis also tested by arranging the measuring system on the gasoline. The rationality of thesimulation results have been proved through the comparative analysis with the experimentalresults.Finally, the dynamic slap force variation in the impact factors has been researched in thefoundation of sensitive parameters of piston dynamic slap force ,mainly selecting engineoperating conditions, piston pin offset and clearance between piston and cylinder as theobjects of the research. By setting different structural parameters and the speed, the pistonsecondary motion have been simulated and analyzed, the characteristics of secondary motionof the piston and mutative regularity of the dynamic slap force have been analyzedemphatically as well, which can lay the foundation for the further researchment on piston slapand provide technical support for the control of the piston dynamic slap force and reduction ofthe mechanical noise in internal combustion engine.