4 Description
Operating manual mzr-11507
10
Technical data subject to change without prior notice!
Last update: August 2016
4
Description
4.1
Micro annular gear pumps
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 2). 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 3). A homogenous flow is generated between the kidney-like
inlet and outlet.
internal
rotor
external
rotor
delivery side
induction side
inlet
outlet
figure 2
Principle of the micro annular gear pump
figure 3
Operating principle of the micro annular gear pump
Reciprocating and rotary pumps have a direct allocation to the fed amount of
the displacement volume
V
g
of the pump and its actuator’s number of
revolutions
n
. The displacement volume describes the volume, which is
theoretically fed with each revolution. The coherence of the flow rate referring
to the formula (= volumetric flow rate)
Q
of the pump is:
n
V
Q
g
Vol
⋅
⋅
=
η
The volumetric efficiency
η
Vol
describes the coherence of the actual flow rate
from the theoretical resulting value. Differences occur according to leaking, as
the sealing on the inside of the pump is done over a gap. The volumetric
