非对称泵直驱液压挖掘机斗杆特性研究

Research on the Characteristics of Asymmetric Pump Directed Controlled Arm Cylinder of Excavator

与阀控系统相比,泵控闭式系统具有无节流损失、驱动与动势能回收一体化的优点,是电液控制技术的发展方向,但对于目前广泛应用的单出杆液压缸,采用传统的进出口流量对称型液压泵,需要附加复杂的流量补偿回路平衡液压缸的面积差,在负载方向改变时会产生压力和速度突变,影响系统运行品质。为解决这些问题,提出一种能够匹配单出杆液压缸面积差的非对称泵闭式系统方案,在对称型轴向柱塞泵的基础上,将原配流窗口由2个修改为3个,其中与原泵出油口连通的窗口不变,连通单出杆液压缸的无杆腔。将原吸油窗口修改为2个,其中1个窗口与单出杆液压缸的有杆腔连通;第3个配流窗口为补偿窗口,与蓄能器或液压油箱连通。建立系统试验台,测试验证该新型系统方案的有效性,进一步将新回路原理用于控制液压挖掘机的斗杆,并对采用新方案后斗杆的运行和能效特性进行联合研究。研究表明,与传统对称泵控系统相比较,新系统具有良好的控制特性,可消除负载方向改变造成的速度波动,同时也显著降低了系统能耗。

Compared with valve system, closed-loop pump controlled system has a number of advantages： compact structure, no throttling losses and integration of driving and kinetic-potential recovery,which has become the development direction of electro hydraulic control technology. But for the widely used single rod cylinder controlled with only one traditional symmetrical pump, an additional compensation circuit must be used to balance flow difference of the cylinder. Besides, due to speed and pressure fluctuation when the load force＇s direction reverses, the system＇s control quality will become poor. For these problems, an asymmetric pump closed controlled system that can match the differential area of a single rod cylinder is put forward. The asymmetrical pump, based on symmetrical pump, modifies the current pump flow matching windows into three ports. The window connected with the symmetrical pump＇s outlet port remains fixed and is connected with the cylinder＇s head side, while the other one is separated into two flow matching windows. The first one is connected with the cylinder＇s rod side,and the second one is a compensation window which can be connected with an accumulator or a tank. The system test platform is established for testing and verifying the effectiveness of the new system. The control performance and energy efficiency of arm cylinder controlled by the asymmetrical pump are researched with established virtual prototype of excavator. The study demonstrates that, compared with traditional pump controlled system, the new system has good control characteristics. The new system can not only eliminate velocity fluctuation caused by the direction change of load force, but can also reduce the energy consumption significantly.