Research On Continuously Variable Valve Drive System Of Diesel Engine

As energy and environmental issues become increasingly severe,higher requirements are placed on energy-saving and emission-reducing engines.The variable valve technology achieves the goal of improving the engine dynamic performance and improving the emission and fuel economy by adjusting the valve lift and timing to achieve ideal intake and exhaust effects under various speeds and loads.Currently,it is subject to the research institutions and major companies.extensive attention.Based on the analysis of the current research status of variable valve technology,this paper proposes a set of variable valve actuation system for bottom camshaft diesel engine.It is used to realize the flexible valve event of diesel engine,and its structure design and working principle are introduced in detail..A multi-body simulation model was established by multi-body dynamics simulation software ADAMS.The valve lift,speed,acceleration and contact force between components were analyzed under different rotational speeds and eccentric rotation angles.The results show that the eccentric can be adjusted within the range of 0 to 180.The valve lift can be continuously variable in the range of 0.9 mm to 10.8 mm.The valve seating speed does not exceed 0.2 at different eccentric rotation angles and different engine speeds.m/s;The contact force curve between the parts is stable and there is no flying off phenomenon,which meets the requirements of the valve train under different load and speed of the engine.The middle push rod was flexibly processed through the finite element analysis software ANSYS,and a rigid-flexible hybrid multi-body dynamics simulation model was established in conjunction with ADAMS software.The effect of intermediate push rod deformation on the system was studied.The results showed that the intermediate push rod The deformation of the valve has little influence on the kinematics of the valve and the contact force between the parts,and the design of the middle push rod is reasonable.Finally,the influence of different valve clearances on the system under cold state is studied and analyzed.The results show that the effect of valve clearance is mainly reflected in the opening and closing time of the valve.Excessive valve clearance will increase the valve seating speed and increase the seating shock.The contact force between the components increases,so in order to meet the engine’s requirements for the valve train mechanism,a suitable valve clearance should be selected so as not to affect the normal operation of the system.