| The role of valve train is to realize ventilation process,in other words, according tothe work order of the engine cylinder, opening and closing the intake and exhaust valvetiming to ensure that the cylinder to rule out exhaust gas and sucked into the freshair.With the speed of the internal combustion engine, valve dynamics can not be ignored.In the case of better fullness ratio of the valve lift curve, minimize the valve trainvibration, noise as well as abnormal wear, in order to ensure the reliability of the valvetrain and improve service life.This article is based on a diesel engine exhaust valve train as the main object ofstudy. From the view of kinematics and dynamics, Analysis the reason of Unreliableexhaust valve.By optimizing the cam profile, improve the mechanical properties ofthe exhaust valve system, thereby improving the reliability of the exhaust valve. Themain contents are as follows:Firstly, Utilize the three-dimensional solid model and material Parameters,combined with CAD/CAM/CAE software CATIA to strike the desired mass andstiffness Parameters of the component.Use the provided rocker location map and springdrawing to define the rocker arm ratio and the valve spring element.For the differenceof Kinematics and dynamics，using AVL_ExciteTD build dual-mass kinematic modeland multi-quality dynamic model.Secondly, respectively calculated on kinematic and dynamic models, analysis of themain performance Parameters. The kinematics analysis can be found, the discontinuityof data measured cam and low fullness ratio of the valve lift curve; Dynamics analysisfound that, due to the exhaust rocker arm with a Jacobs type brake, high speedperformance is poor, along with the high seated velocity and additional vibration.Finally, taking into account the low service life of the exhaust valve and the lack ofkinematics and dynamics performance, re-design the cam profile and modify some ofthe Parameters to improve the overall performance of the valve train. |
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