US 12,228,441 B2
Method for monitoring a Coriolis mass flow meter
Alfred Rieder, Landshut (DE); and Hao Zhu, Freising (DE)
Assigned to Endress+Hauser Flowtec AG, Reinach (CH)
Appl. No. 17/996,800
Filed by Endress+Hauser Flowtec AG, Reinach (CH)
PCT Filed Mar. 23, 2021, PCT No. PCT/EP2021/057464
§ 371(c)(1), (2) Date Oct. 21, 2022,
PCT Pub. No. WO2021/213765, PCT Pub. Date Oct. 28, 2021.
Claims priority of application No. 10 2020 111 127.4 (DE), filed on Apr. 23, 2020.
Prior Publication US 2023/0184573 A1, Jun. 15, 2023
Int. Cl. G01F 1/84 (2006.01)
CPC G01F 1/8436 (2013.01) 15 Claims
OG exemplary drawing
 
1. A method for monitoring a Coriolis mass flow meter, the flow meter comprising an oscillator including at least one measurement tube, an exciter and two oscillation sensors, the method comprising:
exciting the oscillator using the exciter as to cause flexural vibrations of a first antisymmetric vibration mode in response to an excitation signal applied to the oscillator at a resonance frequency of the first antisymmetric vibration mode
wherein the exciter is offset from a center of the at least one measurement tube in a longitudinal direction, and
wherein the exciter is offset not more than 5% of a measurement tube length in the longitudinal direction relative to the center of the at least one measurement tube such that symmetry breaking caused by an asymmetric mounting of that exciter is limited, which symmetry breaking causes a phase difference between vibrations of the two oscillation sensors upon excitation of the oscillator with an eigenfrequency of a symmetric drive mode;
sensing a vibration amplitude of the first antisymmetric vibration mode at the resonance frequency of the first antisymmetric vibration mode;
sensing a time constant of the decaying free vibrations of the first antisymmetric vibration mode; and
determining a modal elastic property of the oscillator with respect to the first antisymmetric vibration mode based on the vibration amplitude of the first antisymmetric vibration mode, the excitation signal and the time constant.