| The second milestone,which as the development of internal combustion engines is turbocharging technology.Its function has developed from plateau power compensation to comprehensive improvement of engine performance,and is developing towards compound turbocharging characterized by turbine output power.Turbocharging technology has become an inseparable part of engine technology,which has a significant impact on the power and economy of internal combustion engines.In the sequential turbocharging system,the switching valve is a key component,which plays a key role in realizing the energy distribution of the parallel supercharger,the pressure ratio,flow adjustment and matching of all working conditions with different engine operating conditions.In this paper,the impact dynamic response process of the switching valve of the turbocharging system under five different closing times is analyzed and studied,and compared with the theoretical solution;the finite element simulation analysis was carried out on the switching valve of the turbocharging system under different driving torque,gas pressure and temperature,and the influences of the three factors on the switching valve of the turbocharging system are compared;select the key dimensions of the valve plate and the valve shaft as design variables,and take the maximum stress and the maximum pressure of the contact surface as the main optimization goals to complete the multi-objective of the turbocharging system switching valve Response surface optimization.Main research content:（1）The transient dynamic finite element simulation study of the switching valve closing process of the turbocharging system is conducted,and the instantaneous speed and the peak stress of the contact surface are obtained when the contact times of the switching valve closing time of the turbocharging system are under five operating conditions of 0.3s、0.5s、0.6s、0.7s and 0.9s.The speed deviation rate is about 2% and the peak stress deviation rate of the contact surface is within 10% compared with the theoretical calculation results.（2）The steady-state simulation analysis of 4 driving torques and 5 gas pressures of the switching valve of the turbocharging system under normal temperature conditions,and the thermal-structural coupling simulation analysis under 4 high temperature conditions are completed.Comparing the simulation results: the deformation of the switching valve of the turbocharging system mainly occurs on the valve plate and the valve shaft under the action of different driving torque,gas pressure and temperature,and the deformation part of the valve plate is mainly concentrated in the transition part from the valve shaft to the contact surface,and is distributed symmetrically;under the action of different factors,the deformation,stress,contact surface pressure and frictional stress of the contact surface of the switching valve of the turbocharging system have the same distribution law,and show a gradually increasing trend with the increase of different factors;Through comparative analysis,temperature is the most important factor affecting the reliability of the switching valve of the turbocharging system.（3）Based on the Central Composite Design method and Kriging method,the size combination of 15 groups of design variables and the multi-objective response surface optimization model of the switching valve of the turbocharging system are obtained;under the same working conditions,the Multi-Objective Genetic Algorithm to solve and calculate,and simulate and analyze the optimized size models respectively,and compare the original design size results: the optimized structure size can effectively reduce the pressure on the contact surface of the switching valve of the turbocharging system and significantly improve the service life. |
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