Research On Key Technology Of Power Split Continuously Variable Transmission

A power split continuously variable transmission (PSCVT) with two-stage step-up gearbox concept in the context of the mini car with engine of FF application was presented in this dissertation. The scheme of PSCVT was designed and verified by simulation. The continuously variable unit(CVU), as the key part of PSCVT was researched deeply by means of combination of simulation calculation and prototyping test. The research was performed as follows:1. PSCVT scheme design. Firstly, the whole scheme of PSCVT was studied and analysised based on the kinematics and mechanics according to the configuration characteristic of the application objection; Secondly, the main PSCVT performance parameters were optimized and confirmed by means of mechanical optimization methodology. Finally, the three-dimension modeling and assembly of the whole gearbox were done and the gearbox configuration was optimized by dint of virtual prototype technology.2. PSCVT performance simulation research. PSCVT mathematic model was established and embedded into the simulation software Advanced Vehicle Simulator (ADVISOR) to finish the whole vehicle modeling with the purpose of estimating the performance PSCVT itself and matching between PSCVT and the whole vehicle. The simulation was carried out according to the chosen vehicle under different driving cycles.3. Electromechanical CVU pulley actuation scheme research and design. As the key part of PSCVT, CVU plays an important role to the whole transmiison performance. An electromechanical CVT pulley actuation system for the variable pulley set (variator) was presented based on the analysis on the other actuation systems for speed ratio control of CVT, and the engineering design as well as prototype manufacture were finished.4. Electromechanical pulley actuation CVU force analysis. The force working on CVU was analyzed and force model was obtained with the purpose of buildbing up theory foundation for the CVU design, the choice as well as the control of actuation motors used for speed ratio shifting and clamping control. The relationship between the pulley clamping force with the torque transmitted by CVU was verified under different speed ratios and the influence that the shape of the instantaneous belt configuration playing to the pulley clamping force was obtained by simulation and calculation to the force model based on the transmission characteristics of PSCVT.5. PSCVT ratio control research. The influence that speed ratio changing rate playing to the vechle performance was obtained by modeling and simulation calculation to the vechile dynamics. To improve the vehicle performance, the ratio control strategy was established and sliding mode variable structure fuzzy controller for the angle displacement of motor which was used to changing the speed ratio of CVU was designed.6. Experiment research on electromechanical pulley actuation CVU. The test rig was established for the electromechanical pulley actuation CVU prototype performance test and the experiment study was done to verify the feasibility of the scheme.The test was comprised of stable test and dynamic test. The former contained the test on relationship between the CVU speed ratio and the motor angle, the law between the CVU transmission efficiency and clamping force, the law between the torque loss as well as the speed loss and the load respectively and the transmission capability of CVU, and the latter was the test on the CVU speed ratio control from initialization to the goal by controlling the motor angle.