Mode-Splitting Resonator for Coriolis Flowmeter Balance Bar Decoupling
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Solution Overview
Problem
Existing Coriolis flow meters face challenges in decoupling vibrations between orthogonal modes, leading to reduced accuracy due to cross-coupling of noise between the Y-direction and Z-direction, which is difficult to address without affecting the flow meter's performance.
Innovation Solution
A mode splitter is introduced for the balance bar, comprising a mass portion and coupling portions with different stiffnesses in the drive and orthogonal directions, effectively isolating vibrations and reducing off-resonance responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a balance bar with substantially square cross-section is used to provide dynamic balance, then the natural frequencies in drive and orthogonal directions are substantially equal, but this causes cross-coupling of noise between directions and reduces measurement accuracy
Solution Approach 1:
The patent applies asymmetry by modifying the balance bar cross-section from a substantially square shape to an asymmetric shape where the dimension in the orthogonal direction is deliberately made different from the dimension in the drive direction. This asymmetric geometry creates different stiffness characteristics in orthogonal versus drive directions, causing the natural frequencies to differ and thereby decoupling the vibration modes to eliminate cross-coupling noise while preserving dynamic balance.
2Measurement precision
If the cross-sectional dimensions of the balance bar are modified to decouple vibrations, then measurement accuracy improves, but this affects the dynamic balance and natural frequency matching
Solution Approach 1:
The patent applies local quality by making a localized geometric modification to the balance bar cross-section. Specifically, one dimension of the cross-section (orthogonal direction) is differentiated from the other dimension (drive direction) while maintaining the overall balance bar structure and its dynamic balance properties. This localized asymmetric modification selectively affects the stiffness and natural frequency in the orthogonal direction without compromising the overall dynamic balance of the system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mode splitter enhances meter accuracy by decoupling vibrations, ensuring the natural frequencies of the drive and orthogonal modes are distinct, thereby improving measurement precision.
Implementation Method 1
The mode splitter comprises a mass portion and coupling portions with different stiffnesses in the drive and orthogonal directions, effectively isolating vibrations and reducing off-resonance responses
Implementation Method 2
coupling portions with different stiffnesses in the drive and orthogonal directions, the second stiffness being different than the first stiffness
Implementation Method 3
Once flow begins through the vibrating tubes, however, a Coriolis force is induced on the tubes
Data Source
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AI summary
A mode splitter (300) for a balance bar (150) of a Coriolis flow meter (100) is disclosed. The mode splitter (300) comprises a mass portion (302), and a first coupling portion (304a) coupled to the mass portion (302). The first coupling portion (304a) has a first stiffness in a drive direction (Y) and a second stiffness direction in an orthogonal direction (Z), and the orthogonal direction (Z) is orthogonal to both the drive direction (Y) and a longitudinal direction of the balance bar (150). The second stiffness is different than the first stiffness.