Simulation And Optimization Design On The Working Device Hydraulic System Of Skid Steer Loader

In recent years, China’s infrastructure has become more perfect, and gradually steps intothe stage of the maintenance. In view of the dense traffic network and the complexconstruction situation in cities, the traditional large-scale engineering machinery has not beengradually suitable for the modernization, so small construction machinery has good prospectsfor development. The typical small construction machinery, skid steer loaders, have a hugeadvantage in road maintenance, snow removal and road urban greening, etc..Compared to foreign skid steer loaders, our technology for skid steer loaders is relativelybackward, but like XCMG, Liugong, Xiagong and other domestic large engineeringmachinery manufacturers, they all put a lot of resource in this area and offer great power forthe development of skid steer loader technology. Based on the school-enterprise cooperationprojects "Research on Performance of Skid Loader Chassis Mechanism", work on thedynamic performance of the skid steer loader’s working hydraulic system and solve theproblem found in experimental test through joint simulation.Based on the theoretical analysis, combining simulation and experiments, study on adomestic certain type of skid steer loader. The specific contents are as follows.Firstly, the current situation and state of skid steer loaders is analysized all over theworld, and the techniques used in the boom structure and working hydraulic system arebriefly described. The development of simulation technology is introduced, and then explainthe techniques used in working system of skid steer loaders in this paper.Secondly, the working principle of the main hydraulic components in the workinghydraulic system is analysized. The modeling features of power bond graph is described, and the mathematical models of the relevant elements are built by the use of power bond graph.Power state equation is obtained by bond graph, and impact factor for the dynamiccharacteristics of the system is clarified.Then, based on the theoretical analysis, with experimental testing for the hydraulicsystem of skid steer loaders, the potential flow variables of pivotal measuring points areanalyzed in detail, which is good for the later simulation. After repeated tests, thephenomenon of bucket valgus exists if the control pressure is kept on when the boom is in thelower position. Considering machine space is little, the decision to study current issues by usesimulation is made.Again, based on the working principle of working hydraulic system, using AMESimbuild hydraulic system modeling, and use LMS Virtual Motion build the dynamics modelingof working device. With comparison of simulation and experiment, illustrate that simulationcan accurately simulate the actual working conditions.Finally, the problem is found coming from the leveling valve. When the boom is in thelower position, if the pilot control pressure of the boom union decreased level in multi-wayvalve is kept on, oil flows into the big chamber of bucket cylinder through damping hole inthe hig-pressure environment, which results in the bucket valgus. By computersimulation verifying, the problem could be soved by equipping with one-way valve on theleveling valve spool, and it is ensured that when the boom lift, the bucket is still able torealize self leveling.