Research On Air-hydraulic Composite Braking System For A Parallel Heavy Duty Hybrid Hydraulic Vehicle

Along with the breakout of energy crisis, energy conservation and emission reduction hasbecome one of the research directions of the car industry. The hydraulic hybrid technology has theadvantages that it has higher power density and the recovery of brake energy is more sufficient. Itis suitable for heavy load, frequent start-stop condition. And it has more superiority in theapplication of engineering machinery, heavy vehicles and the city bus.For modified parallel hydraulic hybrid gas-liquid composite heavy-duty car braking system,the paper mainly conducts the research from the following several aspects:The paper analyzes the structure and operating principles of the gas-liquid composite brakingsystem for a parallel heavy duty hydraulic hybrid vehicle. Meanwhile, paper expounds severalcommon braking conditions. Proposed a retrofit scheme for a parallel heavy duty hybrid hydraulicvehicle. Based on the reform of the braking system the paper builds the kinetic equations of thesystem and mathematical models of the key components.Based on existing braking control strategies of hydraulic hybrid vehicle, the paper makes thecontrol strategy on the composite system. According to the requirements of braking intensity,combined with the pressure of the accumulator, the efficiency of the secondary components andother parameters aiming at maximum energy recovery，the system achieved the goal that allocateand control the gas-liquid braking torque and the front and back brake force reasonably.Model and simulate the gas and liquid composite braking system. Apply the AMESim buildthe model of accumulator, secondary components, electrical proportional valve and other keyelements and analyze the dynamic characteristics. At the same time, established the physicalmodels and the control strategy simulation model and analyze the simulation results.Make a test bench based on real vehicle platform. A variety of experimental studies ofhydraulic regenerative braking performance are taken on the test bench. The correctness of thesimulation models is verified by the experiments results.