Energy-Saving Research On Hoisting Closed-Loop Hydraulic System Of Luffing Tower Crane

Luffing tower crane, which is a special kind of tower crane. It changes its working range by changing the pitch of boom. Because of its extraordinary structure, it is more and more widely used in recent years. Hoisting mechanism is a very important part in its working mechanisms. Since closed-loop hydraulic system has many advantages against open-loop hydraulic system, the hoisting system of large-tonnage luffing tower cranes usually use closed-loop hydraulic system recently. Considering the particularity of the hoisting system’s working condition, there is a lot of energy wasted when the load is lowered. With the concerning issues like shortage of fuel supply and deterioration of environment, it is quite necessary to study this project.Corresponding to this actual project problem, based on hydraulic system of LH2200-100 luffing tower crane, this article performs simulation and energy conservation research, designs a new type of closed-loop hydraulic energy-regenerative system that can be used in hoisting mechanism, and through simulation research, the energy-saving effect and factors influence the efficiency are analyzed. At last, to enhance the efficiency of this system, two types of control strategies are presented.The specific work and achievements are summarized as follows:(1) According to related articles, the basic principle and characteristic of common open-loop system and closed-loop system for hoist mechanism are analyzed.(2) Based on actual project, the components and selection principle of LH2200-100 luffing tower crane hoisting mechanism hydraulic system are introduced, the calculate formula of the system is described as well.(3) The transfer functions of closed-loop hydraulic pump motor speed control system are derived theoretically.(4) The simulation model of hoisting mechanism closed-loop hydraulic system is established and one hoisting working condition is analyzed.(5) According to hoisting mechanism closed-loop hydraulic system, a new type of energy-regenerative system is proposed, the energy-saving efficiency and factors influence the efficiency are simulated.(6) Displacement control strategy of the pump/motor secondary unit and number control of the hydraulic accumulator are designed, with software AMESim and SIMULINK co-simulation, the energy-saving efficiency of this system is further improved.