Hydraulic gear oil pump trapped oil noise and noise reduction strategy
When the gear oil pump is working, a part of the hydraulic oil is trapped in the closed volume formed by the meshing of two pairs of gears and the suction and pressure oil chambers are not connected. When its capacity decreases from large to small, the trapped hydraulic oil is squeezed, and the pressure and speed increase, which is much higher than the output pressure of the gear oil pump
In recent years, the mute has been an important technical index of hydraulic gear oil pump, however, because the flow and pressure pulsation of gear oil pump is its inherent characteristics, the cause of noise is more complex, only from the theoretical analysis is often difficult to find the cause of noise, must be aimed at the different situations of noise, take different methods and measures, can be beneficial to reduce noise.
The following is the gear oil pump trapped oil noise and noise reduction method:
1. causes of noise:
When the gear oil pump is working, a part of the hydraulic oil is trapped in the closed volume formed by the meshing of two pairs of gears and the suction and pressure oil chambers are not connected. When its capacity decreases from large to small, the trapped hydraulic oil is squeezed, and the pressure speed increases, which is much higher than the output pressure of the gear oil pump (the trapped liquid is forcibly squeezed out of the leakable gap), So that the shaft and bearing are subjected to considerable impact load, causing vibration and noise; and when the trapped oil volume increases from small to large, a local vacuum is formed, the dissolved gas in the oil can be separated, resulting in "cavitation" phenomenon, resulting in cavitation, vibration and noise.
2. noise reduction raiders:
1. The external meshing hydraulic gear oil pump mainly opens "unloading grooves" on internal parts such as shaft sleeves (or inverted plates) ". The principle of slotting is to ensure that the high and low pressure chambers inside the gear oil pump do not communicate with each other, and try to make the trapped oil volume communicate with the high pressure chamber or the low pressure chamber, so as to partially remove the trapped oil phenomenon, thereby reducing noise and vibration.
2. Increase the volumetric efficiency of the gear oil pump, reduce the internal drainage of the gear oil pump, thereby reducing the flow and pressure pulsation of the pump, and achieve the purpose of reducing noise, that is, the pump selects a high-precision integral 8-shaped sleeve and uses Axial automatic compensation structure reduces leakage in the end face and increases the volumetric efficiency of the pump. At the same time, the arrangement of the riveting groove of the shaft sleeve is improved, and the asymmetrical discharge groove is adopted to reduce the noise caused by the trapped oil.
3, the use of conjugate curve of the internal meshing gear structure, reduce the phenomenon of trapped oil. For example, the external gear profile of a certain internal meshing hydraulic gear oil pump uses a straight line, while the internal gear profile is a conjugate line of straight money. The geometric shape of this pair of gear profiles determines that the trapped oil volume changes little. At the same time, because the pressure oil is led out from the bottom hole between the internal gear teeth, there is basically no trapped oil area during operation, so the gear pair transmission is quite stable and without impact, and the pulsation of pump flow and pressure is very small, in addition, the inlet area of the oil suction cavity is large, the oil absorption is sufficient, and it will not cause cavitation. Therefore, the noise of this pump is very low, which can be reduced to 55 ~ 65dB, and the application prospect is good.