闭式泵控液气储能重载举升机构特性研究

Research on Characteristics of Heavy-load Lifting Machinery Based on Hydraulic-gas Energy Storage and Closed Displacement Controlled System

采用变转速泵控缸闭式系统的重载举升机构,在超越负载工况下,若不采用制动电阻或能量回收装置,系统将由于电机不能支撑反向负载而失控。但制动电阻消耗电机的发电能量,降低系统能效,增加系统散热负担。针对上述问题,提出一种基于液气储能的重载举升机构闭式泵控三腔液压缸系统,并将其应用于液压挖掘机动臂。液压泵与三腔液压缸的无杆腔和有杆腔连接,控制动臂运行;配重腔与蓄能器连接平衡挖掘机执行机构的重量,直接回收利用执行机构的势能。研究中,首先确定三腔液压缸和蓄能器的参数,然后设计系统的控制策略,最后构建闭式泵控三腔液压缸的挖掘机动臂试验系统,验证系统的可行性。试验结果表明,合理设置蓄能器的压力,不仅可以实现动臂势能的直接回收利用,而且可以使电机始终处于电动状态,提高系统的可控性和能量效率,与负载敏感控制的三腔液压缸系统相比,液压泵输出能量降低27.2%。

When the heavy-load lifting machinery using variable speed displacement controlled cylinder system moves downwards,if there are no braking resistors or energy recovery device,the system will not be controlled due to that the electrical motor can’t sustain reverse load.However,the braking resistors consumes the generation energy of electrical motor,decreases the energy efficiency of the system and increases the heat dispassion burden.In order to solve the above problems,a closed displacement controlled three-chamber cylinder system of heavy-load lifting system based on hydraulic-gas energy storage is proposed.In the system,hydraulic pump is connected with the rod-less chamber and rod chamber of the three-chamber cylinder to control the lifting machinery to move.The weight balancing chamber of the three-chamber cylinder connected with an accumulator balances the weight of the lifting machinery to directly recycle the potential energy,which can improve the energy efficiency and the operation performance of the system.To research the working performance and energy efficiency of the system,it is used to control the boom of a hydraulic excavator.The parameters of the three-chamber cylinder and the accumulator is determined firstly and then the control strategy of the proposed system is designed.Finally,the test platform of the hydraulic excavator boom controlled by the proposed system is built and the system feasibility is validated.The testing results show that appropriate accumulator pressure not only can realize the boom potential energy recycling to improve the system energy efficiency,but also can keep the electrical motor working in motoring condition to improve the system controllability.Compared with the three-chamber cylinder controlled by the load-sensing system,the output energy of the hydraulic pump in the proposed system decreases by 27.2%.