Instantaneous flow rate of gear micropump under trapped oil

The medium in the pump is non compressed. With the continuous rotation of the gear pair at the speed of ω, the volume extrusion region of E1, O1, N, O2, E2 will be formed in the output cavity of the pump, and its change rate is the theoretical output flow rate qxy of the pump. In fact, due to the need of leakage and trapped oil unloading, part of the flow in qxy will return to the pump input cavity in the way of leakage and unloading.

Then, the theoretical and practical instantaneous flow rate qxy, QSH is:


Qrz — leakage flow

QKZ — unloading flow

And the corresponding fluctuation coefficient δ ‘Q, δ q is: 1

Where Max (), min () and ave () denote the maximum, minimum and mean values in ().

The leakage flow qrz mainly includes radial leakage flow QR and axial leakage flow QZ. Qrz is generally calculated by static method. For the determined tooth profile parameters, radial clearance, axial clearance and medium properties, qrz is mainly a function of outlet pressure Po, and the influence factor will be used here

Krz method, and no longer give the relevant detailed calculation formula. Namely:

The unloading flow QKZ mainly includes the unloading flow QGK at the notch and the unloading flow qgz at the axial gap. Because of the dynamic property of trapped oil pressure P (s), it should be calculated by dynamic method.