Study On Energy-Saving Technology Of Hydraulic Excavator Based On Power Match

Hydraulic excavator, a multi-function construction equipment and typical machine of mechantronics technology, requires higher efficiency of fuel consumption and the leading trend and topic of technology development of excavator is in energy-saving study. The energy-saving controls of hydraulic excavator directly affects the economic-capability and reliability of itself.Integrated control system, which combines engine and main pump and control valve, is installed in foreign excavators and greatly improves the performance of excavator. The research aims at the project (BE2001015) named "Computer-aided control system of excavator"supported by Technology committee of Jiangsu Province and takes into account the technologic level of domestic excavator and foreign technology nowadays. The purpose of this research is in pursuit of high operation efficiency of excavator and to study the energy saving controls of hydraulic excavators, which can reduce heat generation of hydraulic system and fuel consumption.The work of this dissertation is as follows: 1. First of all, the background of this dissertation and the significance of energy saving controls of hydraulic excavator in China are introduced,the dissertation also summaries the history of mechantronics developments of hydraulic excavator and application of energy saving technology aboard at the present time.The loss of energy occurs while excavator is at operation,and the cause which leads to loss of energy are presented in this dissertation. 2. Hydraulic transmission and control technology is basic of energy saving system of excavator,the development and progress of excavator are contributed to the progress of hydraulic components and control methods of hydraulic system.The sorts of and control methods of and characteristic of hydraulic system are described in details in the dissertation.And several power control methods and their complex are also introduced and power loss of negative control system is analyzed in quantum of proof. The negative control system produced by Kawasaki Corp., which applies in domestic excavator at large, is analyzed in details as well. 3. Taking medium class crawler-typed excavator as an example, the models and mathematics equations of the components and system of excavator power system are built in this dissertation.The models include engine model, pump model, engine-pump match model. Based on test data, the dissertation builds Cummins 6BT diesel timing curves and pressure-displacement curves of K3V112 pump. The most of domestic excavator adopt constant power hydraulic system which set power value is under that of engine. A scheme has been put forward, which is that the power value of the pump is above that of the engine, according to the analysis of the power match of excavator. The main controller controls the output of the pump while the load pressure changes and the pump can absorb the output of the engine totally, and then engine runs steadily and follows the measured speed. The output of pump varies with the wok conditions and the excavator mainly operations under the conditions of the heavy task, standard task and light load. And engine runs in different speeds when rated power, lowest oil consumption and top torque are aimed at respectively. So the match of engine and pump come into being three power modes:heavy work mode(engine runs at the rated power speed), standard work mode(engine runs at lowest oil consumption speed) and lower load mode(engine runs at top torque speed). Attentions to bad conditions of excavator operation are referred to in design of throttle controller. The DC servo motor is adopted as core component of throttle controller and the equation of DC servo motor is deduced in the dissertation. 4. Being combined theory with practical function of excavator, the electronic energy saving control system, which based on the variable displacement control of pump and throttle control of engine, is designed and developed. The control system comprises main controller (pump controller) and engine throttle controller. The pump controller regulates the displacement of pump according to the variety of engine speed and the throttle controller. The main controller receives inputs from engine speed dial and the speed sensor, power mode selector switch. The controller processes these inputs and sends a control signal to proportional reducing valve solenoid. The proportional reducing valve changes the electric signal to a hydraulic...