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Little problem with the hydraulic pump
On the common knowledge of hydraulic pump, we know a lot, but there will be some of us not too common hydraulic pump phenomenon, such as trapped oil. So what is the trapped oil phenomenon, how this situation is the attack? How can we better deal with this problem? Don't worry, BRAINIAC. We'll find out. Trapped Oil is a common phenomenon in the pump, which is widely existed in the positive displacement hydraulic pump. The primary reason for this is that there is a closed volume between the oil suction and the pressure chamber, and the size of the volume changes. In order to hydraulic pump normal operation, the pump suction, pressure oil cavity is necessary to be firmly isolated, and the pump's closed working volume in the end of oil absorption must be transferred to the pressure oil cavity, in the transfer process, when the closed working volume is neither communicated with the oil absorption cavity nor communicated with the pressure oil cavity, the sealed oil volume is formed; if the size of the sealed oil volume changes, the hydraulic oil sealed in the volume is squeezed or expanded, in the oil seal volume on the attack on the local high pressure or hole, so the occurrence of trapped oil phenomenon. The methods to deal with the trapped oil are: Opening Unloading Groove, opening damping groove or damping hole, controlling the composition of oil sealing area, etc. . In the Axial Piston pump, the bottom volume of the piston will be trapped in the process of oil suction and pressure transfer, because the spacing angle of the port port is larger than the distribution angle of the cylinder bore. In order to reduce the harm of trapped oil, it can be eliminated by adopting structural methods on the distribution window of the distribution plate: for example, opening a damping groove or a damping hole at the front of the distribution window, when the dead volume of the bottom of the plunger changes, it is communicated with the oil pressure chamber or Oil Suction Chamber, to make the bottom of the plunger sealed volume to complete pre-contraction or pre-expansion can slow down the sudden change in pressure. For double-effect Vane Pump, as the circular arc section of the stator is the transfer direction of the pump suction and pressure oil cavity, the Central Angle of the circular arc section should be larger than the angle between the interval angle of the suction and pressure oil window and the blade, so that the size of the closed volume will not change, trapping phenomenon will not attack. In the external gear pump, for the sake of the smoothness of the gear transmission, it is required that the overlap degree is & GT; 1, so two pairs of gear teeth will mesh together. At this point, the closed volume formed by the two pairs of gear teeth meshing together is not connected with either the oil pressure chamber or the Oil Suction Chamber, and the volume first decreases from large to small and then increases from small to large, thus causing the phenomenon of trapped oil, in order to eliminate the phenomenon of gear pump trapped oil, usually in the pump before, after the cover plate or floating side plate, floating shaft sleeve on the unloading groove.