Mechanical-Hydraulic Co-Simulation On Working Device Of Medium-Sized Hydraulic Excavator And The Optimization Of The Valve Structre

Excavators are widely used in industrial and civilian construction as a kind ofengineering machines. The hydraulic excavator is developing rapidly because of itsexcellent performance and advantages of index. While the efficiency of data mining andreliability are determined by the performance of the hydraulic excavator working unit, thestability of the hydraulic system is determined by the multitandem valve. Therefore, theunceasing improvement and innovation of the working device structure, the hydraulicsystem and the multitandem valve is key to the future development of the hydraulicexcavators.The study of the excavator working devices can be devided into two parts, on onehand the structure and the movement of the working device were analyzed, while on theother hand its hydraulic system was analyzed.A20-ton class hydraulic excavator was taken as the object of study in this thesis. Onbasis of that, the excavator model is built up in LMS Virtual.lab Mation and the dynamicsanalysis of the excavator was simulated. The other model is built up in AMESim and itshydraulic system was simulated. Then the Co-Simulation model is built and the wholesystem was simplely analyzed.The related data was verified by experiments. Finally thisthesis comes up with some suggestions on the improvement of the valves.This thesis is divided into the following parts.In the first part the background and the purpose of this thesis were elaborated and thestudy and the developing trend of hydraulic excavators both at home and abroad, as well asthe hydraulic technology and the simulation skills were introduced.In the second part theoretical analysis and kinematic simulation analysis of theworking device were conducted. First the movement of excavator’s working device wesanalysised by D-H coordinate system theory then a whole machine model was built inCATIA. In LMS Virtual.lab Motion the model is simplified and the whole machinedynamic model was bulit. At last the kinematics analysis of the excavators was performedand the envelop line of the excavators were simulated. In the third part the hydraulic system of the working device was introduced. First theprinciple of the Separate hydraulic circuit in excavator working devices was introduced.Then a multitandem valve and superstructure hydraulic system model is built in AMESimand simple analysis of the hydraulic system was conducted.In the fourth part a Co-Simulation analysis was provided. An interface is set up inAMESim and LMS Virtual.lab Motion, and the Co-Simulation of the mechanical systemand hydraulic system were performed. The working course of the excavators in reality canbe simulated in order to make the simulation data close to the experimental data, whichprovides basis for further experiment.In the fifth part experiment on the working of the excavators in reality was conducted,so the data like the pressure and flow can be measured. On one hand, the excavator isrequired to repeat every movement for several times and every time is tracked. On the otherhand, a whole digging process will be followed to collect data. Finally, the data collectedwill be combined for analysis.In the sixth part several suggestions to improve the structures of the valves were putup. On one hand the flow is needed to be increased, so the idea of increasing folw byincreasing the number of oil inlet and outlet channels was promoted, on the other hand thecontrol segment was consided.It was based on the following principle in order to reduce theimpact from bemoulli force.By the way the movement of valve rod can be controlledexactly.