How to solve the cavitation phenomenon of the gear pump


Four failures of the gear pump in the laboratory: cavitation, tooth surface wear, side plate wear, and suction line intake were studied. The gear pump is CBG2004 type, and the theoretical displacement is 40.60. By adjusting the throttle valve on the suction line of the gear pump, the pump is artificially created to generate air pockets, that is, the population vacuum of the pump is increased to 0.06 MPa, so that the pump experiences no The process of air pockets to severe air pockets. During the test, the pump speed was fixed, and the outlet pressures were 0.5, 3.5, 7.9, and 12.5 MPa, respectively. The flow pulsation signal of the gear pump drain port was measured before and after the cavitation, and the change of the pump outlet pressure was observed at the same time.
Waveform of the output flow of the pump under different loading pressures with time. As can be seen:
(l) When the gear pump does not generate air pockets, the output flow of the oil pump is basically constant, and the outlet pressure is also basically unchanged.
(2) When the gear pump generates cavitation and cavitation, the output flow of the pump drops significantly, and the outlet pressure of the pump does not decrease significantly. Sometimes, the pressure remains basically constant.
(3) As the population vacuum of the gear pump increases, the output flow of the pump decreases, the flow pulsation increases, the flow rate in the first 105 decreases, and the output pressure remains basically unchanged; conversely, when the population vacuum decreases, the pump The output flow rises and the flow pulsation weakens.
(4) Under the same population vacuum condition, when the set pressure of the loading relief valve is different, the pulsation characteristics of the output flow of the gear pump are also different, and the outlet pressure signal has no obvious fluctuation. When the external load pressure is low, the amplitude of the high-frequency pulsation portion of the outlet flow rate at which the gear pump generates cavitation and cavitation is small, and the amplitude of the low-frequency pulsation portion is large. When the external load pressure is high, the flow pulsation when the gear pump is cavitation is obviously aggravated, and the amplitude of the high-frequency pulsation portion becomes large. Since the outlet pressure is high, the high-pressure oil leaking back into the suction chamber increases, and thus the flow waveform is in the flow chart. There is a lot of "reflow" phenomenon.