RF Cavity Resonator for Passive Fluid Sensing

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Solution Overview

Problem

Existing remote sensing systems for fluid measurement in remote, isolated, or hazardous environments face challenges due to high power consumption and communication requirements, which increase system costs and limit design flexibility in applications such as bulk fluid storage, chemical production, and hazardous environments.

Innovation Solution

A remote sensing system utilizing a cavity resonator that shifts its resonance frequency in response to thermodynamic contact with process fluids, allowing for accurate fluid parameter measurement without the need for continuous power, using a tuner to adjust the resonance frequency and a signal coupler to transmit echoes when the resonance frequency matches the query signal, enabling wireless or cabled communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional remote sensing systems are used for fluid measurement, then measurement capability is provided, but power consumption and communication requirements increase system cost and limit design flexibility

Engineering Contradiction:
Improvefluid measurement accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The sensor system operates passively without requiring an internal power source. The cavity resonator uses the energy from incoming query signals to generate echoes, effectively serving itself by converting electromagnetic energy into resonant responses that carry measurement data about fluid parameters.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces traditional active electronic sensing mechanisms with a passive resonant cavity system. Instead of using powered sensors that actively transmit data, the system uses electromagnetic resonance phenomena where the cavity naturally responds to query signals, substituting mechanical/electronic active components with passive physical phenomena.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If traditional remote sensing systems are used for fluid measurement, then measurement capability is provided, but communication requirements increase system cost and complexity

Engineering Contradiction:
Improvefluid measurement accuracyVSAvoidcommunication requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the communication function from the sensing function. The cavity resonator solely provides measurement data through its resonant frequency characteristics, while a separate transceiver system handles all communication tasks. This separation simplifies the sensor design and reduces communication complexity at the sensor level.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a transceiver system as an intermediary between the passive cavity resonator and the external monitoring system. The transceiver translates the resonator's physical resonance into communicable signals, mediating between the simple passive sensor and the complex communication requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If the cavity resonance frequency is fixed, then manufacturing is simplified, but adaptability to different fluid parameters and conditions is reduced

Engineering Contradiction:
Improvecavity manufacturing simplicityVSAvoidresonance frequency adjustment
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent makes the previously static cavity resonator dynamic by introducing a tunable element. The resonant frequency can now be adjusted or tuned to match different fluid conditions and parameters, allowing the same physical cavity to adapt to various measurement requirements while maintaining manufacturing simplicity.

Inventive Principle:
Principle #15Dynamics

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 solution provides precise and cost-effective fluid parameter measurement in challenging environments by directly responding to pressure, temperature, and flow variables, reducing power consumption and communication complexities, and allowing for both wireless and cabled embodiments suitable for various hazardous conditions.

Implementation Method 1

a cavity configured to resonate at a central resonance frequency... a waveguide or RF cavity resonator having a resonance frequency that shifts in response to thermodynamic (pressure or thermal) contact with a process fluid

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

thermodynamic (pressure or thermal) contact with a process fluid

Methodology Applied
Scientific EffectThermal contact: Conduction (thermal)

Implementation Method 3

The tuner is coupled to the cavity, and tunes the resonance frequency by adjusting the cavity's effective resonance length

Methodology Applied
Scientific EffectResonance frequency tuning: Resonance

Implementation Method 4

The signal coupler is also coupled to the cavity, and is configured to transmit an echo when an incoming query signal matches the tuned and shifted resonance frequency

Methodology Applied
Scientific EffectEcho: Echo

Data Source

PatentEP2417445B1RF cavity-based process fluid sensor
Publication Date: 2016.07.20 ROSEMOUNT INC
  • EP2417445B1 patent drawingFigure 1
  • EP2417445B1 patent drawingFigure 2A~2B
  • EP2417445B1 patent drawingFigure 3A~3B

AI summary

A remote system for sensing a process fluid parameter comprises a cavity, a tuner and a signal coupler. The cavity is configured to resonate at a central frequency that shifts in response to the process fluid parameter. The tuner is configured to tune the central frequency. The signal coupler is configured to receive a query signal, and to transmit an echo signal when the query signal matches the shifted central frequency.