Research on axial thrust balance of water pump

Balance hole can not be too much open, mainly affecting the efficiency of the pump, the following describes some of the axial thrust of the pump balance. For single-stage pump axial force balance generally have the following forms: 1, open a balanced hole Drill a few holes near the hub of the rear cover of the pump and add a seal on the rear cover. The outer diameter of the seal ring is equal to the outer diameter of the suction inlet of the impeller. Pump work, the back cover ring liquid and suction port connected, the pressure and suction port pressure is similar. Seal outside the cover area and the suction port outside the front cover of the same area, thus sending the liquid pressure in the front and rear cover of the total force is basically equal to a small part of the unbalanced axial force by the bearing. Under normal circumstances, a balanced hole balancing axial force better. Its characteristics are: more leakage, through the balanced hole of the liquid and impede the normal flow of impeller liquid inlet, the centrifugal pump to reduce the efficiency of about 2-5%, only for small single-stage centrifugal pump. 2, using balanced pipe This method is the same as the method of opening the balance hole, and a mouth ring is arranged on the rear cover of the impeller corresponding to the suction inlet, the liquid in the sealed space is introduced into the pump inlet by a balance tube, Balance, so that the axial force balance, this device requires cross-flow pipe cross-sectional area should be equal to or greater than the mouth ring gap flow area of ​​4-5 times. 3, the use of balanced leaves In the back of the impeller rear cover symmetrically placed a few radial ribs, when the impeller rotation, the same as the pump blade blade back to the liquid to accelerate the rotation, the centrifugal force increases, so that the pressure on the back of the blade significantly reduced, so that the impeller Both sides of the pressure to achieve balance, the balance depends on the degree of balance of the blade size and the gap between the blade and the pump body. The disadvantage is the pump efficiency is reduced. 4, using double suction impeller In the flow of single-stage centrifugal pump or a few multistage centrifugal pump with double inlet impeller, the thrust is balanced by its own working conditions, but in fact it is difficult for manufacturers to do the pump two Since the geometry of the side-flow components is exactly the same, there is still a small axial force acting on the rotor, so that it is borne by a single-row radial ball bearing on one end of the shaft. In addition, for multi-stage pump axial balance device, the impeller symmetrical arrangement method, balancing hub balance axial force and balance disc balance axial force and other forms can be used.