Small Hydraulic Excavators Throttle Control System Modeling And Simulation Research

With the rapid development of construction machinery in China, the quality and quantity of domestic hydraulic excavator has improved greatly. But because of the huge gap of home and abroad in designing and manufacturing of hydraulic components, most key hydraulic components (pump, main-valve and motor) in domestic hydraulic excavator have to be imported. The profit margin and potential development of domestic excavator industry is restricted badly. Under this background, aiming at connecting the design parameters (hydraulic circuit and throttle) of hydraulic components with the dynamic performance of excavator, the thesis makes research on modeling and simulation of throttle governing system of mini-hydraulic excavator. The main research work as follows:The development status of excavator hydraulic system, computer simulation technology and hydraulic simulation technology is surveyed. Characteristic, typical working condition and fundamental hydraulic circuit of mini-excavator are analyzed. The energy consumption of hydraulic system is analyzed qualitatively. The hydraulic pump controlling methods are discussed.The kinematics and dynamics model of a mini-excavator is established with Adams. The friction resistance moment of slewing bearing is calculated by means of force superposition method. The throttle governing system model of the mini-excavator is established with AMESim. The friction expression of hydraulic cylinder are given. The principle and modeling method of 3 position 6 port hydraulic valve are analyzed. And the program to compute the Orifice area curve is designed with Matlab. The characteristic and selecting method of hydraulic pipe and hydraulic fluid model in AMESim are introduced. The co-simulation principle and method of Adams and AMESim are introduced too.Do the co-simulation of Adams and AMESim. Get the dynamic response of hydraulic system and mechanism according to specific operations. Then by comparing the simulation results and experimental results, the accuracy of the model is verified. These operations include single operation as boom, arm, bucket and swing with different diesel engine speed, and multi- operation as boom&bucket, boom&arm, arm&bucket, boom up&swing. And then by doing the simulation of typical operating condition circle of hydraulic excavator, the dynamic energy consumption distribution is obtained.Generally, the thesis has discussed the method and process of modeling and simulation. The paper provides a novel and convenient method for designing main control valve in mini-excavator.