Research On Oil-charging And Discharging System Characteristics And Control Strategy For A Hydrodynamic Retarder

In this dissertation,based on three dimensional computational fuild dynamics method,theoretical modeling of oil-charging and discharging system,approximate model and bench test,the integration simulation model of working chamber and oil-charging and discharging system for a duel torus hydrodynamic retarder was established.The dynamic braking characteristics controlled by oil-charging and discharging system was analyzed,and the evaluation method for dynamic braking characteristics was proposed,as well as braking control strategy design and optimization.Then bench test verification was conducted.The study achieved fast response and accurate braking control of hydrodynamic retarder with improving dynamic braking characteristics effectively.The tangent-arc blade design method was proposed to obtain cascade parametric design model and automatic modeling for the full flow passage of working chamber with oil-charging and discharging flow passage.The numerical simulation of the impact of oil-charging and discharging flow rate on braking characteristics was conducted with sensitivity analysis.Based on approximate model,the rapid braking characteristics model of working chamber was built.The braking torque error between simulation and test was within 6%,and the computing accuracy of oil pressure was improved,which would provide necessary support for oil-charging and discharging system research.The oil-charging and discharging control scheme was proposed.The steady and transient flow force and flow coefficient of the switch valve and charging regulation valve were obtained,and parameter modification of theoretical model was conducted,contributing to the rapid model of oil-charging and discharging system.Compared to the test data,the steady simulated error of oil pressure was less than 3%,and the dynamic response delay was less than 0.09 s,which could accurately predict the dynamic characteristics of oil-charging and discharging system.The integration model of working chamber and oil-charging and discharging system was built,and the influence of control parameters on braking characteristics was analyzed as well as the braking response and the tubes' influence on braking characteristics.Then the dynamic braking indicators were proposed,and dynamic braking quantitative evaluation method based on improved radar map was presented.The study solved the rapid prediction and evaluation of dynamic braking characteristic for hydrodynamic retarder,and provided foundation for braking control strategy study as well.Based on the integration model and evaluation method,the control strategies of hydrodynamic retarder were studied.The braking strategies of constant deceleration,constant speed and pedal brake were proposed.The constant deceleration control parameters with anti-windup PID controller were optimized.The parallel control of PID and fuzzy for constant speed brake was proposed,and fuzzy control weight was optimized.The self-adjusting fuzzy control method with integral control for pedal brake was proposed,compared with conventional fuzzy control.The results showed that the braking characteristics could be improved obviously.The bench test of hydrodynamic retarder was carried out.The regulating error of braking torque was less than 5.5%,and the response time was less than 1.2s decreasing by60%,compared with the reference prototype.The oil-charging and discharging system could meet fast response and accurate control of hydrodynamic retarder,and the control method based on integration model and evaluation method had good control effect.The test verified the good dynamic prediction accuracy of integration model with dynamic braking torque error of 5.27%.