Dual Sensor Head in Single Thermowell for Flow Switch Reliability
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Solution Overview
Problem
Existing thermal type flow and liquid level sensors face challenges in achieving high reliability with low failure rates, especially in space-constrained environments like aircraft, where dual sensor installations are impractical due to size and weight limitations, leading to potential false positives and costly shutdowns.
Innovation Solution
A dual compact sensor head design providing fully redundant and separated output signals within a single installation location, utilizing two RTD sensors with independent circuit boards to compare temperature differences and prevent false positives, ensuring continued operation even if one sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual sensor assemblies are installed to achieve redundancy and reduce false positives, then reliability is improved, but device complexity and installation space requirements increase
Solution Approach 1:
The patent combines two independent sensor assemblies into a single integrated housing. The first and second sensor assemblies are mounted within the same housing structure, sharing common mounting features, wiring channels, and protective elements. This merging approach achieves the reliability benefits of dual sensors while reducing installation complexity and space requirements compared to separate assemblies.
Solution Approach 2:
The housing structure is designed to serve multiple functions simultaneously: it provides mechanical support for both sensor assemblies, contains the wiring and electrical connections for both sensors, offers protective shielding, and enables single-point installation. This multi-functionality reduces the overall system complexity while maintaining the redundancy needed for high reliability.
2Reliability
If dual sensor assemblies are installed to achieve redundancy, then reliability is improved, but weight and size limitations are exceeded
Solution Approach 1:
By consolidating two sensor assemblies into a single housing, the patent eliminates duplicate structural components, mounting hardware, and protective elements that would exist if two separate assemblies were installed. This sharing of common components significantly reduces the total weight while maintaining the redundancy of having two independent sensing elements.
3Reliability
If dual sensor assemblies are installed in close proximity to achieve redundancy, then reliability is improved, but available installation space is insufficient
Solution Approach 1:
The patent nests the second sensor assembly within the same housing that contains the first sensor assembly. The housing is designed with internal compartments or mounting structures that accommodate both sensors in a nested arrangement, allowing them to be installed in close proximity while maintaining independent sensing functions. This nesting approach minimizes the external footprint and installation space required.
Solution Approach 2:
The housing structure integrates mounting features, wiring channels, and protective elements that serve both sensor assemblies simultaneously. This shared infrastructure reduces the overall installation space required compared to two separate installations, while still providing the redundancy needed for high reliability applications.
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 solution significantly increases sensor reliability, reduces false positives, and allows for advanced warning and alarm signals, ensuring safe operation by maintaining high confidence in fluid flow or liquid level monitoring without the need for additional sensor assemblies.
Implementation Method 1
utilizing two RTD sensors with independent circuit boards to compare temperature differences
Implementation Method 2
Heated flow and liquid level sensors have been available for at least several decades
Data Source
AI summary
A fluid flow or liquid level switch providing a high level of reliability. Dual reference sensors in a single thermowell operates with two active, independent sensors, which operate with independent electronics having dual signal outputs, to provide constant and continuous redundancy in operation.