Design Of Container Sidelifter’s Hydraulic System And Research On Its Synchronous Control Mechanism

Container vehicle with crane (so called side-lifter) is the maintool in the industry of transportation. However, the in-synchronousmovement of the lifters which are controlled by the hydraulic system isa urgent problem needed to be resolved. As a result, the main objectiveof this research is about to design feasible hydraulic systems, based ondifferent controlling mechanism, to realize the synchronous movement ofboth lifters. In this paper, two kinds of hydraulic system were designedaccording to different controlling theory: open-loop controllingmechanism and close-loop controlling mechanism, and the reliability ofboth systems were examined by simulation in software environment.In terms of hydraulic system designed with open-loop controllingmechanism, the synchronous movement of cylinder groups which control themovement of lifter arms was guaranteed by a duplex pump. Both sub-pumpshave the same parameters which can support same flow to the cylinders andensure the movements of pistons of cylinders have same speed. Firstly,physical model of the system was developed and relevant hydrauliccomponents were chosen according to calculation of their ability andcapacity. Then, the operation of system was simulated by the softwareAMESim and the results of simulation reflected the synchronicity ofpistons movement. It was found that the reason causing thein-synchronous movement of piston, when the mass distribution incontainer was not balanced, was the existence of by-pass valve. The curvesreflecting the relationship of load-speed of piston also showed that thein-synchronicity increased with the increment of unbalanced loadingdegree. However, this in-synchronicity was acceptable when the load gapwas controlled around four tons. As a result, the designed hydraulicsystem was available if the unbalanced loading condition was not serious. While for the hydraulic system which was designed using close-loopcontrolling mechanism, the proportional valve was the main componentensuring the synchronous movement of pistons. In this section, thephysical model of hydraulic was simplified at first. Further, amathematical model was development based on the simplified physical modelwhich indicated the relationship between flow and speed of pistons. Also,the derivation of model s transfer function was finished which was usedfor the simulation of the hydraulic system. In the controlling section,a PID controlling model was developed and added into the whole numericalsystem. Simulation of the numerical model was conducted under theenvironment of Simulink and the results showed that the adjust of thedifference in speed was rapid and it did not changed with difference inload, which indicated that this hydraulic system was available andreliable.