Research On Excitation Characteristics Of Valve Train

Valve train is one of the main noise source of internal combustion engine, and the impact of the valve train neighboring components is the main source of internal combustion engine noise and vibration. The 4102BG diesel engine is selected as the research object, it is necessary to research the excitation characteristics of the valve train in depth.A lumped dynamic model of valve train is developed by lumped parameter method. Linear-spring contact model, kelvin contact model, hertz contact model and hertz-hysteresis contact model are used to simplify and establish four contact pairs,which includes the tappet-pushrod contact pair, the pushrod-rocker arm, rocker arm-valve, valve-valve seat. The influences of contact stiffness. The dynamic model is calculated with the finite-difference method by the Fortran77 programming language.Characteristic curves of five contact pairs in four different contact models are used to contrast analysis, the influences of different parameters on contact forces are discussed.A contact forces testing system is built. Because the testing 4102 diesel engine is a bare engine which has a group of valve train, the camshaft is pulled by electric motor. The lack of lubricating system leads to the valve train neighboring components damages, therefore camshaft lubrication system is built. Strain gauges of different contact forces are calibrated, and sensitivities of the contact force measuring strain gauges are calculated. Different contact forces are measured finally, four contact models are verified by a comparison between the test results and the simulation results, and analyse the merits and demerits of four contact models in the calculation of the valve train system.