Abstract:Considering the electro-hydraulic composite braking system of electric loader, a hydraulic braking system based on hydraulic brake valve with regenerative braking free stroke was proposed to meet the braking requirements of multi-working conditions and ensure braking safety. The stroke of hydraulic brake valve was divided into motor regenerative brake free stroke and hydraulic brake stroke, which was one of the judgment conditions for hydraulic brake system intervention. Based on the ideal curves of front and rear wheel braking force distribution for electric loader and the braking strength obtained from the braking intention identification, a distribution curve between braking intensity and the vehicle torque demand was developed. To further improve the coordination of distribution for regenerative braking force and hydraulic braking force while taking into account energy recovery efficiency, a collaborative control strategy of electro-hydraulic composite braking was proposed. When hydraulic braking system was involved, the regenerative braking torque was changed with the hydraulic braking torque, reducing the fluctuation of vehicle total braking torque and ensuring smoothness during the braking mode switching process. Finally, the co-simulation model based on AMESim-Matlab/Simulink was studied, and an experimental prototype was built to verify the feasibility of collaborative control strategy of composite braking for electric loader. The results showed that the energy recovery efficiency was up to 71.6%, the recovery rate of braking was up to 44.5%, and the energy saving was up to 7.6% in one working cycle. The proposed control strategy had good braking performance and energy recovery efficiency.
