| Engineering machines almost are high-power construction machinery. Hydraulic excavator, as the main products of the engineering machines, energy-saving has been a key subject due to lots of reasons, such as continual variety of load, wide range of the variety, worldly energy crisis, and the higher consciousness of the protecting entironment. With the perfecting of the integrative technique between mechanics and electronics continuously, the study on the electronic energy-saving control system of the hydraulic excavator becomes the one of the important developing trends in the engineering machines. The existing foreign hydraulic excavators have witnessed obvious energy-saving especially by equipped with different electronic control systems respectively, and have improved energy-saving for different extent. Comparing with the advanced foreign excavators, energy-saving control technology of domestic excavators still is in the primary stage. Even though some universities and corporations, like Zhejiang University and Guangxi Yuchai Limited Company, have obtained outstanding achievement, but there still are biggish disparities between foreign hydraulic excavators and domestic excavators in the energy-saving, operational reliability. So, it has great significance both theoretical and experimental that to study on the energy saving technology of the hydraulic excavators. The aims of this study are, enhancing the competitive capacity of the domestic excavators and improving the energy saving effect of the control system of the domestic excavators. The dissertation, tied with the projects, special fund of the Ministry of mechanical for excellent talents (96250404), and the fund of the Ministry of Education for the backbone teacher. Analyzing present energy-saving technology on domestic hydraulic excavator and its primary energy-losing firstly, and then investigates energy-saving by incorporating the engine, hydraulic system and load to a dynamic system. The dissertation introduces a new method of energy-saving control in the excavator, and comes with an advanced, intellectualized controller. The innovations in this dissertation are as following: 1. The dissertation analyzes present research situation of hydraulic excavator, introduces the working principle of several advanced hydraulic excavator energy-saving control system, and summarizes the difference between the foreign hydraulic excavators and domestic excavators. As well as points out the research direction and developing trend of hydraulic excavator energy-saving, explains the purpose and significance of research on hydraulic excavator energy-saving control. 2. Energy-losing and energy-saving control theory analysis (1) Analysis of hydraulic excavator energy-saving control theory By analyzing Universal Characteristic Curve and Speed Adjusting Curve of diesel engine, the maximum power point and the minimum oil consuming, which are at different rotation speed when the engine is at the same accelerator position, could be found. So it is important to set the engine rotation speed according to load (on different working station). From Rotation Speed-Oil Consumption Curve, the oil consuming will see rising sharply when the rotation speed waves. The above analysis proves that steady rotation is the most importance to energy-saving. hydraulic excavator energy-saving can be realized via controlling on hydraulic pressure system and power system. (2) Analysis of hydraulic excavator energy-losing The dissertation has discovered various ways of hydraulic excavator energy-losing when working, via analyzing control circuits on hydraulic excavator. The primary energy-losing is brought by the power no-matching between engine and pump, and by the power no-matching between hydraulic system and load, the rest loss is shared by the mechanic losing, kinetic energy-losing and potential energy-losing, pressure losing ofpipeline and low efficiency of pump. The key to energy-saving is to control the flux of hydraulic system according to load regardless of which of the following has been chosen: Positive flux control, Negative flux control and Load Sensing control. 3. Design on the energy-saving control system of the hydraulic excavator Based on the characteristic of hydraulic excavator, the dissertation has incorporated engine, variable pump and load as a dynamic system for energy-saving researching. The power mode of the engine could be marked to 4 levers according the working status. Then self-adaptation control system of the power matching was designed via the exported pump pressure. When the system working, with the load changing, put filtered pump pressure, measured in several working circulations, into controller to get right position of the accelerator and practical rotation speed in power matching principle. The method of adjusting exported power is always set in this way, and it could be achieved that self-matching between the power mode of the engine and working status of the excavator. Improving the using ratio of the fuel oil could be obtained by this method. The dissertation has employed the control method of the rotate speed sensing control. Then power matching are realized by adjusting pump displacement in the certain working status, when the waves of the engine rotate speed and the system pressure have brought by the instantaneous variety of the load. The reason of the power no-matching between engine and pump, pump and load was analyzed first time. And harmonized control method of the power matching between engine and pump, pump and load is brought forward innovatively in this paper. The detailed technique is to realize self-adjusting of the valve opening, by virtue of proportional controlled pilot operated valve, which equip the function of measuring displacement. Transmission theory of the running-equipment was analyzed depending on the energy-saving. Linear running synchronous control circuit of the running motor was designed innovatively, which controlled by flow dividing valve.4. Building the mathematics model of the control system The mathematics models of the drive-working system, which obtained engine, variable displacement pump, valve and cylinder, were built in this paper. Opening-loop transfer function of the system is gained by simplifying the mathematics models. Researching the characteristic of the opened control system of the power working status by the module of Matlab, established the base for the simulink study of the intelligent control arithmetic. Analyzing the characteristic of the running system, which consist of the fixed displacement motor and variable displacement pump, its result indicates that performing constant horsepower control of the variable displacement pump is the most important in the energy-saving control of the running system. 5. The arithmetic study of intelligent control system Lucubrating the theories of the fuzzy control and nerve net control, self-adaptation fuzzy PID controller and single nerve cell PID controller of the dynamical system were designed. The simulink test result indicates that self-adaptation fuzzy PID controller and single nerve cell PID controller could effectively stabilize the rotate speed of the engine in the course of load changing. Comparing two kinds of intelligent control arithmetic, single nerve cell PID controller is the better. 6. Test-bed experiments of energy saving intelligent control system The test was done in the energy-saving control test-bed, which the aim is for validating the reliability and practical effect of the single nerve cell PID controller of the excavator. Experiment proved dynamic pattern mentioned in this dissertation could control the engine perfectly through computer no matter what working stage the hydraulic excavator has been in, middle position loss, over flow loss and loss of flux modulating have been cut down accordingly, oil consuming also showed the average result of the energy-saving control system was above 8.5 percent. Short term overloading has been realized through second level overflow control, which has heightened the efficiency as well as boosted safety. Oil consuming and system radiation has been reduced effectively via automatic idle speed system; the performance of the whole working system has been improved...
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