The Crankshatf System’s Muti-body Dynamics Simulation Analysis Of4EC Engine

NVH analyze has been payed more and mora attention.The designand conditions of operation of the crankshaft has particularly importantinfluence on the engine.Compared to traditional test methods,using theFEM and multi-body dynamics to analyze the dynamics problems of thecrankshaft and NVH characteristics of the engine block has significantadvantages.In this paper,combining the FEM and multi-body dynamicsmethod,multi-body dynamics simulation on the4EC engine crankshaft,the main bearing dynamic properties was studied.In the main bolts ofengine cylinder head,sump and the timing cover,to set degrees offreedom in order to get the output response by the change ofperformance parameters of the crankshaft and powerunite.Then,we canobserve the changes of the engine body noise.The main contents are asfollowed.First,by using CAD software,FEM analysis software,andsimulation software to creat a reasonable4EC engine crankshaft bodydynamic model.Second,complete one working cycle simulationoperations to extract the main bearings’dynamic load and the dynamicresponse of the body bolts.Third,by changing the parameters,such asadjusting the gap between the main bearing,loosning the main bearing atthe horizontal bolt to change the main bearings of the model,as well aschanging the crankshaft material modulus of elasticity,especially whenthe crank mode was adjusted close to the modal of the main bearings toinspect the main bearings’dynamic load and the dynamic response of thebody bolts.In order to get accurate results by the computer,some changesin the model was made.The geometric characteristics of the helical gearon the crankshaft,and some small rounded corners was removed.UsingRBE2to instead the cylinder head,oil pan,timing cover,etc.This greatly simplifies the model,shorten the computing time.Secondly,when dividing the finite element mesh,to deal withstructural discretization,that is,according to the crankshaft and the body’sown structural characteristics and load conditions,different regions of thegrid density level was divided in order to control the number of the grids.Then the model could reflect the actual working conditions.Then,import finite element model into ABAQUS to calculate themodal and get the natural frequency characteristics of the model.In oederto reduce the time for computation,modal compression was performed.A.exb file contains*.DOFT,*.GEOM,*.OUT4,*.KDIC,*.KELM was got fornext calculation.After EXCITE multi-bdy dynamic simulation,the dynamic load of themain bearings was extracted in the form of the response curve.Thencompare response curves to the ones that after changing the parameters.We could also obtain the body’NVH feather.