Simulation Analysis And Research On The Dynamic Characteristics Of Double Intake-exhaust Valve Engine

The multi-body system dynamics analysis model of double intake-exhaust valve train was established based on multi-body dynamics theory and visual prototype technique in this study. The dynamic and stress characteristics of double intake-exhaust valve were analyzed when the valve eccentricity seated according to the relevant information offered by the enterprise.Firstly, based on the multi-body dynamics theory, the three dimensional solid models of relevant parts of double intake-exhaust valve train, such as valve, valve guide, valve seat, valve bridge, rock arm and tappet were built using the software Pro/e, then they were assembled according to the actual connections. Finally the assembly model was imported to the software ADAMS to create the dynamic analysis model of double intake-exhaust valve train.Secondly, the incompatibility problems of dynamic characteristics, such as the valve lift, velocity, acceleration and the contact force between tappet and cam, were analyzed according to the model and the working parameters of the double intake-exhaust valve train supplied from the enterprise. The improvement design scheme of double intake-exhaust valve train was proposed and the effects of different parameters, such as valve train's centralized quality, spring rigidity and valve train's damping coefficients, on the dynamic characteristics were researched. The results show that the dynamic characteristics, such as the valve velocity and acceleration increased with the cam speed, valve train's stiffness and centralized quality and decreased with the valve train's damping coefficient. The contact force between tappet and cam decreased with the valve train's damping coefficients obviously. The parameters of the valve train were optimized and the incompatibility problem was improved effectively.Finally, the stress characteristics of the valve train were studied in the abnormal conditions. The assembly model of double intake-exhaust valve train on the eccentricity sitting was firstly built by the software Pro/e, and then was imported into the finite element analysis software ANSYS-workbench. Then the effects of the clearance (ΔD) between valve and valve guide and the valve cone angle (β) on valve stress were analyzed, and the reasonable values ofΔD andβwere discussed. The results show that whenΔD was smaller than 0.22 mm, the maximum stress and the second hot spot stress present a stable value, whereas, whenΔD was beyond 0.22 mm, the above stresses increased withΔD sharply. Furthermore, the effects ofΔD andβon valve stress were mutual coupling, that was, whenΔD was 0.22 mm, the maximum surface stress increased withβ, while the second hot spot stress firstly decreased and then increased withβ. Meanwhile, whenβis 45°, the second hot spot stress reached the minimum. Therefore, the reasonable value is thatΔD is 0.22 mm andβis 45°.