Braking characteristics integrating open working chamber model and hydraulic control system model in a hydrodynamic retarder

Hydraulic control system has important influence on the steady and transient braking performance of a hydrodynamic retarder. The braking characteristics of hydrodynamic retarder regulated by hydraulic control system should be investigated first, before designing and making the braking strategy and control method. The accurate and detailed braking characteristics models of open working chamber and hydraulic control system are established, integrated, and validated by steady and dynamic experimental data. Based on full factorial design experimental method, the influence of control parameters on braking performance achieving steady state is analyzed with parameter sensitivity, and the effect of control parameters on braking response characteristics is conducted. Then the influence of different tube lengths between working chamber and hydraulic control system on braking performance is discussed and analyzed. The results show the control pressure and rotor rotational speed both have significant impact on braking characteristics with obvious nonlinear, coupling, and interaction effect. The longer response time of hydraulic control system will be for the larger braking torque. Shortening the tube lengths as much as possible is needed to improve the braking torque, cooling flow rate, and system integration.