Mass flowmeter according to the Coriolis principle with at least two measuring tube pairs and method for determining the mass flow

摘要

The invention discloses a mass flowmeter (100) according to the Coriolis principle, comprising two measuring tube pairs of different useful natural frequencies, each having an electrodynamic exciter (140a, 140c) for inducing bending vibrations and a pair of vibration sensors (142a-1, 142a-2, 142c-1, 142c-2) for detecting bending vibrations at two positions of a pair of measuring tubes; and an operation and evaluation circuit (160); for driving the exciter with a common exciter signal and for detecting signals of the vibration sensors; for determining flow-dependent phase differences between the signals of the inlet-side and outlet-side vibration sensors of one of the vibration sensor pairs and for determining mass flow measurements on the basis of these flow-dependent phase differences; wherein in each case an inlet-side and outlet-side sensor signal path is adapted to transmit sensor signals superimposed on both pairs of measuring tube; wherein the operating and evaluation circuit is adapted to perform a zero point correction for the first pair of measuring tubes and / or the second pair of measuring tubes in consideration of signal amplitude ratios of the pairs of measuring tubes when determining the mass flow measured values on the basis of flow-dependent phase differences.