4 Description of the micro annular gear pump
Operating manual mzr-2521 and mzr-2921
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Technical data subject to change without prior notice!
Last update: June 2019
4
Description of the micro annular gear pump
4.1
Operating principle of the micro annular gear pump
Micro annular gear pumps are positive displacement pumps. They contain two
rotors bearing slightly eccentrically to each other; an externally toothed internal
rotor and an annular, internally toothed external rotor (see figure 6). Due to their
cycloid indenting, the rotors remain interlocked at any time, forming during
rotation a system of several sealed pumping chambers. As the rotors revolve
around their offset axis, the pumping chambers increase on the induction
(suction) side and simultaneously decrease on the delivery side of the pump (see
figure 7). A homogenous flow is generated between the kidney-like inlet and
outlet.
internal
rotor
external
rotor
delivery side
induction side
inlet
outlet
figure 6
Principle of the micro annular gear pump
figure 7
Operating principle of the micro annular gear pump
In the case of rotary displacement pumps, the delivered amount of liquid may be
easily calculated form the displacement volume
V
g
of the pump and the number
of revolutions of the rotor
n
. Displacement volume stands for the volume of liquid
that is moved within one revolution cycle of the rotor. This relation is illustrated
by the following formula:
n
V
Q
g
Vol
⋅
⋅
=
η
The volumetric efficiency
η
Vol
shows the relation between the actual and the
theoretical flow rate values. The existing differences result from internal
movement of the liquid during the operation.