Potential Energy Recovery System Of Electric Heavy Forklift Based On Double Hydraulic Motor Generator

Non-road mobile construction machinery with traditional fuel engine as the power source has the problems of high energy consumption,high emission and high pollution,which has a great impact on global climate.Under the background of energy conservation,environmental protection and green development,the pure electric drive construction machinery has become a new development direction with the characteristics of low noise,zero emission and no pollution.At present,the main pure electric drive forklifts in the domestic and foreign markets are small forklifts of less than 5 tons,and the research on heavy forklifts of 25 tons or more is not mature.This paper focuses on the potential energy recovery of pure electric drive heavy forklifts to provide some basic research for the development of pure electric drive heavy forklifts.Firstly,this paper introduces the main control methods of the hydraulic cylinder’s descending speed,compares and analyzes the characteristics of the hydraulic motor generator driving methods with different displacements and variable speeds,and determines hydraulic cylinder’s descending control method.Aiming at the problem of low recovery efficiency at low speed,this paper designed a double hydraulic motor generator potential energy recovery scheme,introduced the characteristics of the new potential energy recovery scheme,proposed the control strategy of the double hydraulic motor generator potential energy recovery system.Secondly,the mathematical models of three different control systems are established,and the response and stability of the system are analyzed.Based on AMESim,the simulation models of three different control methods are established,and the operating performance of forklift under three different control methods is analyzed.In this paper,the lifting cylinder descending characteristics of the double hydraulic motor generator potential energy recovery system are studied,and the speed response and followability,mode switching characteristics and low-descending speed stability are analyzed in detail.The simulation results show that the operation of the double hydraulic motor generator potential energy recoverysystem has good operation performance.At last,according to the basic function requirements of the whole machine and the potential energy recovery control strategy,the design and development of the whole machine control system are completed.Complete the whole machine construction,design and write the whole machine control program,complete the whole machine function debugging.It is proved that the double hydraulic motor generator potential energy recovery system has good operating performance and the simulation model is correct.At the same time,the effects of different loads and different descent speeds on the potential energy recovery efficiency are also studied.The tests show that the recovery efficiency of the potential energy recovery system of the double hydraulic motor generator is between 11.48% and 80.18% under different loads and different descending speeds.By analyzing the tast data,the potential energy recovery control strategy is optimized,the energy saving estimation and test summary under the standard operating conditions of the system are completed.