溢流阀溢流损耗能量回收系统研究

Energy Regeneration System for Pressure Differential Loss Energy in Hydraulic Relief Valve

溢流阀作为三大液压阀之一,广泛应用于各种液压系统中,其出口一般接油箱,进口压力由用户设定;溢流阀阀口压差即为进出口压力差,压力等级越大,阀口压差损耗越大,溢流阀口的损耗压差被认为是不能降低的。研究提出一种通过在溢流阀的出口连接能量回收装置的结构方案,通过能量回收单元提高溢流阀的出口压力,降低比例溢流阀进出口压差的方法来降低溢流能量损耗。利用CFD软件建立比例溢流阀的流场仿真模型,分析了能量回收单元对溢流阀稳态液动力的影响。搭建了溢流损耗能量回收试验平台,试验结果表明:采用能量回收单元提高溢流阀出口压力后,不仅大大降低了溢流阀阀口的能量消耗,同时也降低了作用于阀芯的液动力和调压偏差,而溢流流量基本不受影响。

Relief valve is widely used in the industrial machinery. Commonly, because output port of relief valve is connected to the tank, the pressure drop of the relief valve is equal to the input pressure. Thus, the efficiency of the relief valve cannot be very high, which will be worse as the rated pressure of hydraulic system increases. Firstly, an energy regeneration unit connected to the output port of a relief valve is developed to recover overflow energy loss. The regeneration unit makes the output pressure of the relief valve far greater than that in the tank and reduces the pressure drop. Then, the effects of the back pressure on the distribution of the flow field and the pressure control characteristics are analyzed through CFD simulation and experiment. The results show that with the increase of the back pressure, the displacement of the main valve spool increases and the reset spring force increases accordingly. While the steady state flow force decreases dramatically with the increase of the back pressure, which results in a smaller pressure differential. The pressure differential can be reduced from 15% to 2.5%. It is also observed that the flow rate of the relief valve can be maintained at a certain value with a small oscillation. This verifies that the outlet of the relief valve connecting to the energy recovery unit to recovery the overflow energy loss cannot reduce the pressure control characteristics, but can achieve a better pressure control accuracy of the relief valve.