Simulation Study On Closed Hydraulic System In Hoisting Mechanism Of Crawler Crane

Crawler crane is a kind of widely used of mobile hoisting equipment. As one of the most important mechanisms of crawler crane, the dynamic properties of hoisting mechanism directly affect the working performance of the whole machine. At present, most of the international manufacturers have adopted the closed hydraulic system, however only a small number of domestic products used in such a controlling way. That is because the closed hydraulic system used in the hoisting mechanism is still at the trying design stage and lacks the theory support. So using the hydraulic system simulation analysis methods to solving the key problems during the large crawler cranes design is of great significance.In this paper, the dynamic simulation study on the closed hydraulic system in the hoisting mechanism is on the background of the subject-1250t crawler crane, which is jointly developed by school of mechanical engineering of DUT and Foton Lovol International Heavy Industries Co., Ltd.(1) Based on the study of the closed hydraulic system principle and the characteristics of the closed hydraulic system, the key technologies of the closed hydraulic system applied in the hoisting mechanism are put forward, and the study focus of this paper is summed up.(2) The hydraulic principle of the hoisting mechanism of 1250t crawler crane is designed. According to the calculation results of selection condition of the hoisting mechanism, the components are selected.(3) Considered for the nonlinearities of the hydraulic system and the bulk modular, the features of the subsystems in the hoisting mechanism are analyzed, and the bond graph models of the variable displacement pump, the auxiliary pump, the hydraulic motor etc. are built up. Then, according to the interaction between subsystems, the bond graph model of the whole mechanism is developed.(4) Based on the 20-sim simulation software, the bond graph model of the hoisting mechanism with closed hydraulic system is built up; and the parameters and constraints are set. Finally, the model solution is achieved.(5) Using the simulation results, firstly, the influence of the suction pressure is analyzed; secondly, the pressure memory control is detailedly studied, the parameters optimization in the pressure memory control, the influence of fluctuations of the memory pressure, and the influence of the load change to the optimization results are discussed; thirdly, the load lowering control is detailedly studied, and the effect of the brake release time to the load lowering control is analyzed. A new load lowering control method is put forward, and the superiority of the method is validated through the simulation; finally, the effort of the auxiliary pump pressure and displacement are discussed.In summary, this paper presents a complete dynamic simulation and optimization study on the hoisting mechanism with closed hydraulic system using the bond graph method. All study results not only play an important theory-instructing role in improvement, optimization and design of hoisting hydraulic system, but also have a good chance to be applied in practice.