Research On Output Coupled Hydraulic Hybird Powertrain

With the rapid development of automobile industry in the world, energy resources shortageand environmental pollution problem are becoming more and more severe, so the developmentof energy-saving, environmentally-friendly vehicle is increasingly becoming an important taskfor the society. Hybrid technique is an effective way to alleviate energy resources crisis andenvironmental deterioration before a new and clean energy technique comes into full play.Hydraulic hybrid vehicles as one of hybrid vehicles is highly valued by governments andresearch institutions gradually, because it can recycle brake energy efficiently.After looking up and reading a lot of related literatures and reference materials at home andabroad, out-coupled hydraulic hybrid powertrain is studied based on the technology ofhydro-mechanical power split transmission. The main research work of this paper includes thefollowing:(1) They are analyzed that the work principle and structure forms of hydro-mechanicalpower split transmission in this thesis, and then, the transmission strategy and the designparameters are determined. Based on the above work, they are studied that operational mode，power flow characteristic, speed characteristic of the out coupled power split transmission. Then,speed control mode is put forwarded.(2) On the basis of hydro-mechanical power split transmission and energy regenerationsystem, the structure of out-coupled hydraulic hybrid powertrain is constructed. They are studiedthat operational mode，power flow characteristic of the out-coupled hydraulic hybrid powertrain.And then, its energy control strategy is designed.(3) By using Simulink and Simscape module of Matlab, the simulation model ofhydro-mechanical power split transmission and braking energy regeneration system isestablished. The simulation of the Hydro-Mechanical power split transmission was madeinputted by UDDS. The results confirm the validity of the transmission scheme, parameterdesign and speed control mode. The simulation of the energy regeneration system was made.Simulation results show that the braking energy recovery utilization of up to49%, and the higherinitial work pressure of hydraulic accumulator, the shorter braking time for vehicle.