Coil State Monitoring via Ohmic Resistance Comparison
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Solution Overview
Problem
Vibronic sensors face challenges in maintaining reliability and safety integrity, particularly at high temperatures, due to limitations in piezoelectric materials and the need for effective condition monitoring of coils within these sensors.
Innovation Solution
A method for monitoring the condition of coils with at least two connection wires by determining the total ohmic resistance, comparing actual and target values, and using status indicators to diagnose defects such as shorted turns or poor electrical contact, which can be applied to vibronic sensors and other measuring devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If piezoelectric materials are used for the drive/receiver unit, then conversion efficiency is improved, but temperature range is limited to approx. 300°C
Solution Approach 1:
The patent changes the material parameter from piezoelectric to electromagnetic drive/receiver units, which fundamentally alters the operating temperature range from limited to -200°C to 500°C while maintaining conversion efficiency through electromagnetic induction principles
2Temperature
If high-temperature piezoceramic materials are used, then temperature range is extended above 300°C, but effectiveness is significantly reduced and mechanical stress causes fracture
Solution Approach 1:
The patent replaces the mechanical stress-prone piezoelectric ceramic system with an electromagnetic drive/receiver unit that uses magnetic fields for actuation, eliminating the mechanical stress issue that causes fracture in high-temperature piezoceramic materials while maintaining operational effectiveness across a wide temperature range
3Reliability
If condition monitoring of coil is implemented, then reliability is improved, but device complexity is increased
Solution Approach 1:
The patent implements self-service condition monitoring where the coil itself serves as the sensor for detecting its own health status through electrical resistance measurements. The existing excitation signal is used to monitor coil condition without requiring separate monitoring hardware, thereby improving reliability while minimizing added complexity
Solution Approach 2:
The patent introduces feedback by continuously measuring the electrical resistance of the coil and comparing it against expected values to detect changes in coil condition. This feedback mechanism enables real-time monitoring of coil health, allowing for early detection of degradation or failure modes
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
This approach enables precise condition monitoring and enhances the functional safety of measuring devices by detecting malfunctions and ensuring reliable operation, even in safety-critical applications.
Implementation Method 1
The drive/receiver unit excites the mechanically oscillatable unit to mechanical oscillations by means of an electrical excitation signal... In the case of flowmeters, however, the mechanically oscillatable unit can also be designed as an oscillatable tube through which the respective medium flows
Implementation Method 2
the drive/receiver unit can receive the mechanical vibrations of the mechanically oscillatable unit and convert them into an electrical reception signal
Implementation Method 3
Determining a target value of a total ohmic resistance for the coil and the connecting wires... determining an actual value of the total ohmic resistance at least on the basis of the received signal
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
The invention relates to a method for monitoring the state of a coil (17) with at least two connection wires (d1, d2), said coil (17) being part of a device (1) for determining at least one process variable of a medium (4) in a container (5), and to a device (1) for determining process variables of a medium (4) in a container (5), said device being capable of carrying out a method according to the invention. The method has the following steps: - ascertaining a target value (Rges,ref) of an ohmic total resistance for the coil (17) and the connection wires (d1,d2), - applying an electric excitation signal to the coil (17) and receiving an electric received signal from the coil (17) by means of the two connection wires (d1,d2), - ascertaining an actual value (Rges) of the ohmic total resistance at least using the received signal, and - comparing the actual value (Rges) with the target value (Rges,ref) and ascertaining a state indicator using the comparison.