The Study Of Automatic Shifting Theory And Control System Of Constructin Machinary

The working condition of construction machineries is always bad, and the driver must shift the gear frequently. The shift operation makes the driver tired and reduces the working efficiency. The automatic transmission technology is a way to promote the working efficiency of construction machineries.Refers to the achievements the predecessors have attained, the purpose of this Ph.D dissertation is to study the theory and engineering technology of automatic transmission, and implement the automatic control of the hydrodynamic transmission of ZLM50 wheel loader, including the design of hardware and software, the control technique and the simulation technique. The dissertation includes seven chapters:In chapter one, the history of automatic transmission and its application on construction machineries are introduced. The general structure and function of automatic transmission are illustrated. And the aim of its application on construction machineries is analyzed in detail.In chapter two, the driver-loader-environment model is established. The powertrain system of wheel loader and the parts' characteristics are analyzed. The model of diesel, torque convertor, the gearbox model and environment resistance are established.In chapter three, Base on the analysis of wheel loader's operation characteristics, the driver model is established. Base on the analysis of wheel loader's working conditions, the environment model is established. The driver-loader-environment model is the foundation of the shift strategy test, fuel economic estimate.the fuel consumption of Multi-operating-mode-driving-cycle is defined as a new index of fuel economic, and the time consumption of Multi-operating-mode-driving-cycle is defined as a new index of working efficiency and power characteristics.In chapter four, the reason of shifting impact is analyzed. For improving the shifting quality, an optimized pressure curve of wet clutch is established. The curve has been validated by test.In chapter five, the scheme of the control system of automatic transmission is established, and the shifting strategy is also established.In chapter six, the hardware of the TCU is developed and tested. The reliability and safety is considered during the whole design process of TCU. The software structure of the TCU is designed based on Real-Time-Operating-system, and coding of basic software module is finished. The function test of whole automatic transmission control system is carried out on test bed. The result of experiment shows the design of the control system is successful.Chapter seven is the summary of the dissertation, the main research achievements are showed, the problems requiring further studies are discussed.