Mechanism Analysis Of Collision Between Piston And Stigma For Valve Train In 265 Diesel Engine

The normal operation of the valve train of the internal combustion engine determines the stability and working efficiency of its operation.The collision between the piston and the valve often occurs during the operation of the internal combustion engine.Therefore,it is very important to study its collision mechanism in depth.For the collision problem between piston and valve in the valve train of type 265 diesel engine,the full text takes the crankshaft axis as the coordinate origin a 3D parametric model is established in CREO3.0.The analysis of the multi-rigid kinematics is carried out to obtain the curves of the displacement,velocity and acceleration for the valve and piston motion.The result shows the maximum displacement of the piston is 999.96 mm,the maximum speed is 2670.84 mm/s,the maximum displacement of the valve is 1020.47 mm,and the maximum speed is 303.58 mm/s.It is also found that when the cam rotates clockwise from 48.39° to 129.16°,the piston and the valve may collide in the same or reverse direction.The 3D parametric model of the valve train mechanism is made by CREO3.0.And it is imported into ADAMS,HYPERMESH and ANSYS.And then the rigid-flexible multi-body dynamics analysis of the valve train is carried out to obtain the curves of displacement,velocity and acceleration for the valve and piston motion.The result shows in the encounter collision,the maximum displacement of the piston is 997.90mm,the maximum speed is 2715.90mm/s,the maximum acceleration is 3718.37m/s2,the maximum displacement of the valve is 1019.20mm,the maximum speed is 361.40mm/s,and the maximum acceleration is 295.83m/s2;In the chase collision,the maximum displacement of the piston is 997.90mm,the maximum speed is 2718.40mm/s,the maximum acceleration is 2854.07m/s2,the maximum displacement of the valve is 1019.20mm,the maximum speed is 423.90mm/s,and the maximum acceleration is 393.04m/s2;The maximum collision force between the piston and the valve is 7063.20N,and the maximum collision stress on the valve is 43.68MPa.Since the collision stress is less than the yield limit of the valve material,the elastic deformation is generated.Two analysis results are compared.The analysis results show that the rigid-flexible coupling dynamics analysis is better than the multi-rigid dynamic analysis.The reasons for the collision between the stigma and the piston involves the phase error of the cam,the wear and machining defects of the camshaft and the follower roller,machining defects,gear assembly errors,loose coupling bolts,and the clearance errors of bearing and bushing,etc.The research results of this paper have certain reference value for the design of internal combustion engine,and also provide the relevant basis for the optimization design of valve train.