充液阀系对液力缓速器制动转矩起效的迟滞影响

Baking rapidly is one of the core requirements of heavy duty vehicles with hydrodynamic retarder auxiliary braking system, but it is difficult to consider the influence of the flow state in valve system in the transient braking process of the hydrodynamic retarder in which working medium changes from the gas phase to the liquid phase, which leads to the large deviation of the initialization time by simulation compared with test data. In order to obtain the influence of the valve system on the fluid filling process so as to accurately predict braking initialization time, hydraulic and hydrodynamic integrated flow system computational models with and without control valves are built. The full gas phase flow field in the hydrodynamic retarder is taken as the initial condition for the transient numerical simulation of the fluid filling, and the flow velocity of charging valve discharging valve are tanken as boundary conditions, and the transient trend of braking torque and the distribution characteristics of flow field parameters in the integrated flow system in the process of filling and braking of two models are simulated and verified by experiment. The results show that the charging valve had obvious effect on the brake torque hysteresis effect, and there are obvious deviations if valves are not considered, and especially the prediction of the initialization time is too idealistic and up to 4 s hysteresis, while he computational model of hydraulic and hydrodynamic integrated flow system with charging and discharging valves system isproved to be more accurate and the initialization time deviation is reduced to 0.8 s.The prediction method in this paper can provide theoretical basis for the design of dynamic braking control strategy and the design of vehicle braking system with hydrodynamic retarder.