The Key Technique Research of the 4WD Parallel-Series Hybrid Electric Vehicle of CAF6470E

As the rapid development of automobile industrial, the environmental problem becomes serious increasingly. Because the key techniques of electrical automobile have few breakthroughs, the hybrid electric vehicle (HEV for short) will show its special advantages in a very long time. At present, there are few domestic researches on 4WD HEV, the study of the key techniques is still in a beginning stage. The research of this paper is based on 4WD HEV of CFA6470E, the control optimization of the engine, fuel economy optimization, power split, control strategy and so on are composed.A proper reequipment and arrangement of the whole vehicle is applied based on the original vehicle. Through calculation, the preferences and selection of the drive and power components are confirmed, as well as the selection and design of the key components, and the arrangement of each component.Based on the experiment data of the engine, the best fuel economy is confirmed. Considering of the electronic throttle and CVT, the rev characteristic of the engine in best fuel economy is achieved, and the desire ratio of CVT is ascertained according to the requirement of the best fuel economy.An equivalent model for charge/recharge modes of the 4WD hybrid electric vehicles is proposed through the method of the equivalent fuel consumption. When the engine is operated within the ranges of the best fuel economy, the desired operation curve (DOC) is derived based on the definition of optimization target function for the effective specific fuel consumption. The optimization result is obtained by simulation, and the result shows that optimal combinations of control variables among engine and every motor are defined from DOC.According to the HEV with CVT, the structure of the hybrid system, the drive modes and the drive power split have been researched. The cooperation control of the engine, motors, clutches and CVT enables the system to achieve the sufficient response and smoothness in drive mode split, the best economy match of the engine and the transmission is obtained as well, the shift and control of the clutches are automatic.Considering the characteristic of 4WD HEV and each component, the corresponding control method is proposed. The simulative model is founded, the energy management is suggested based on the vehivle speed, the states of the engine, motors and battery are optimized, and the optimization result is obtained.