Study On Torque Computing And Vibration Of Camshaft In Engine Valve System

The design of the valve train will affect the function of whole engine directly, sothere is more and more people pay attention to the investigation of it. The paper aimingat the overhead camshaft valve mechanism, give motion and dynamic analysis to it, thetheoretical solution is derived by the load torque of camshaft, and thus load torque ofthe valve train camshafts in several typical speed were calculated. A valve train finiteelement model of internal combustion engine has been developed using ANSA fortransient simulation analysis, then the contact force of tappet and valve train cam、valvespeed、valve displacement、valve velocity、valve acceleration data and so on werecalculated at several typical uniform speed of camshaft, thus to calculate the simulationresult of camshaft load torque value. By mutual comparison of the theoretical resultswith simulation results, the theoretical formula and simulation analysis were reciprocalauthentication for each other, and verify the correctness of the finite element model.By the valve transient finite element analysis, combined with instantaneousconstraints modal analysis of the camshaft, the camshaft vibration nature was bereceived, as well as the relation of camshaft vibration size and the camshaft speedvariation. At the sometime, the torsional vibration on valve train has been analysis.According to bending vibration trend, the main factors affecting the camshaft bendvibration were got, after that the effective methods to control camshaft vibration havebeen proposed.The main research and conclusions of this paper are as follows:①Analyzed the forces of camshaft system, and deduced the theoretical formulaof the camshaft load torque. Make use of the theoretical formula to calculatethe load torque camshaft in several commonly used velocities for the Valvemodel which this paper studied.②To simplify modalities of single cam valve train system and established itsfinite element model, then make the simulation analysis，based on thesimulation data calculate the load torque of camshaft. Comparing the result oftheoretical calculation and simulation result, it is show that two resultagreement each other very much, the theoretical formula and simulationanalysis were reciprocal authentication for each other, and verify thecorrectness of the finite element model. ③According to the simplified modalities and the method which the modelestablished of the single cam valve train, the whole valve train system has beensimplified and its finite element model has been established, then its transientsimulation analysis has been done, based on the simulation data calculate theload torque of camshaft, and the results were compared with the single camvalve train camshaft load torque, the two results show good agreement, so thecorrectness of the finite element model of the whole valve train has beenverified.④The valve train system camshaft vibration response analysis model has beenestablished and its transient analysis has been done, as well as the camshaftconstraint modal analysis, its vibration response has been researched combinedwith the transient analysis results and the camshaft constraint modal analysis.We got the bending vibration characteristics of the camshaft, as well as therelation curve of camshaft bending vibration size and velocity of camshaft.⑤The valve train system camshaft torsional vibration response analysis modelhas been established. Analyzed the torsional vibration of the camshaft and thecamshaft free modal. The result show that camshaft has a little torsionalvibration but have not torsional resonance, the main factor which effect thecamshaft torsional vibration is the measurement of load.⑥Reasons of the bending vibrations of the camshaft has been studied, thenanalyzed the effect of rigidity of camshaft、width of camshaft bearing seat forcamshaft bending vibrations, According to the analysis results several effectiveways to control the camshaft bending vibration has been given.