Research On The Relationship Between The Dynamics Performance Of Hybrid Electric Forklift Mast And Potential Energy Recovery

As the energy crisis getting serious, people’s requirements of energy saving of construction machinery are increasing. Potential energy recovery and utilization are considered to be one of the important solution to solve the problem of construction machinery energy saving. How to improve the efficiency of potential energy recovery has become the key problem of the research of construction mechanical potential energy recovery system.This dissertation takes a’National Key New Product’scheme as the background, takes a hybrid electric forklift as research object, implements research on base of the overall analysis of hybrid construction machinery research status, research and application situation of potential energy recovery system. The potential energy recovery technology of hybrid electric forklift is studied, the relationship between the dynamics performance of hybrid electric forklift mast and the potential energy recovery efficiency is analyzed, technical solution and control strategy of potential energy recovery system is designed, the basic principles of mast dynamic optimization design are proposed. The primary work and results include the following aspects.1) Composition and working principle of conventional electric forklift working device are analyzed. The problems existing in the conventional electric forklift working device system were pointed out. Based on the measured working data of electric forklift, the feasibility of the working device system potential energy recovery and reuse are researched, the proportion of recoverable energy of lifting cylinder and tilting cylinder is analyzed.2) Mathematical model of hybrid electric forklift potential energy recovery system is established. Using established mathematical model, the relationship between the dynamics performance parameters of hybrid electric forklift mast and the potential energy recovery efficiency is derived, the relationship between the parameters of crucial parts in the potential energy recovery system and the potential energy recovery efficiency is derived, too. Simulation model of hybrid electric forklift potential energy recovery system based on AMESim and Virtual.lab Motion software was established. Using established simulation model, potential energy recovery system is analyzed. The correctness of theoretical study is proved.3) Aiming at the problems existing in the working device system, the potential energy recovery system of hybrid electric forklift based on the double power source and variable speed volumetric speed control is proposed. The mathematical models of potential energy recovery system based on the double power source and variable speed volumetric speed control system are constructed. The control performace of system is analyzed. Fuzzy PI control system for motor speed control and fuzzy controller are designed, control strategy based on fuzzy theory is proposed.4) The potential energy recovery system based on variable speed volumetric speed control and throttling auxiliary speed control is proposed. The mathematical model of potential energy recovery system based on compound speed control is constructed. The control performace of system is analyzed. Crucial parts in the potential energy recovery system are designed. The decision-making way of fork working mode is analyzed. The control rule of the generator speed is discussed. A compound control strategy that consists of throttling auxiliary speed control and variable speed volumetric speed control is presented.5) Based on the basic factors determined dynamic performance of forklift mast and structural feature of forklift mast, eight principles of structural dynamic optimization design for forklift mast was set forth. The obtained principles have great practical values for the structural design of forklift mast.6) Using the research results make prototype, experimental study is carried out on the prototype. The effectiveness of simulation model and the accuracy of simulation results are tested by experimental results. The contrast experimental results of conventional electric forklift and the hybrid electric forklift with potential energy recovery system show that the hybrid electric forklift with potential energy recovery system can lengthen working hours by11.6%, potential energy recovery effect is obvious. Hybrid electric forklift with potential energy recovery system avoid lead-acid battery large current discharge, can effectively extend the service life of lead-acid battery. It can decrease the cost of the use of electric forklift.