Interlocking Sensor Mount for Cryogenic Thermal Isolation
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Solution Overview
Problem
Sensors in extreme temperature environments, such as cryogenic fuel tanks, often malfunction due to ice buildup when not properly thermally isolated, leading to malfunctions in automotive, aviation, and aerospace applications.
Innovation Solution
A thermally-isolated sensor mount with interlocking segments providing high thermal resistance, utilizing natural gaps between microscopic surface waviness and asperities, and adjustable surface roughness and emissivity coatings to maintain sensor operation in extreme temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor is mounted directly on a cryogenic fuel tank substrate, then the sensor can be easily installed and structurally simple, but the sensor will be exposed to extreme cold temperatures causing ice buildup and malfunction
Solution Approach 1:
The sensor mount is divided into multiple discrete segments (first segment, second segment, third segment) that can be assembled together. Each segment serves a specific thermal isolation function, allowing the complex thermal protection to be broken down into manageable components that are easier to manufacture and install.
Solution Approach 2:
The mount structure uses nested segments where the second segment is positioned within the first segment, and the third segment is positioned within the second segment. This nested configuration creates multiple thermal barriers in series, significantly increasing thermal resistance while maintaining a compact overall structure.
2Temperature
If multiple interlocking segments are used to increase thermal isolation, then thermal resistance increases and sensor protection improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Different segments of the mount are designed with different local properties optimized for their specific functions. For example, external surfaces have specific emissivity characteristics for thermal radiation control, while internal surfaces have specific roughness characteristics for gap thermal resistance. This localized optimization allows each segment to be manufactured independently with focused quality control.
Solution Approach 2:
The interlocking segments are designed with adjustable fit tolerances (ANSI fit classes RC1-9) that allow the assembly to be tuned for optimal thermal performance. The gaps between segments can be controlled during assembly to achieve desired thermal resistance levels, providing flexibility in manufacturing and field installation.
3Strength
If the sensor mount is made compact and rugged, then the device size is reduced and structural strength is improved, but the thermal isolation capability may be compromised
Solution Approach 1:
The sensor mount segments are made from materials with low thermal conductivity (such as polymers or composite materials) that provide both structural strength and thermal isolation properties. This allows the mount to maintain mechanical integrity while effectively blocking heat transfer from the cryogenic substrate to the sensor.
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 ensures proper sensor operation in extreme temperatures by preventing ice buildup and maintaining thermal isolation, applicable to various applications including spacecraft, aircraft, and industrial settings.
Implementation Method 1
Natural gaps between the interlocking layers due to microscopic surface waviness and asperities increase the thermal resistance between adjoining surfaces. This is known as 'gap thermal resistance.'
Implementation Method 2
Various combinations of surface roughness and tightness of fit or pressure (such as ANSI fit class RC1-9) and external surface emissivity coatings can be determined by analysis and testing
Data Source
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AI summary
A thermally-isolated sensor mounting structure, including at least two, nested, interlocking segments, including a lower segment and an upper segment attached to the lower segment, with one or more gaps between the upper and lower segments. The upper segment comprises a passageway for holding a sensor probe. The sensor mount can be a prismatic assembly that uses dovetail joints, or a threaded cylindrical assembly that is screwed together. The sensor mount can be attached to a substrate that is extremely cold or hot. Gap thermal resistance between the upper and lower segments plus optional optical coatings isolates the sensor probe from extreme temperatures. Mating surfaces can be artificially roughened or polished to increase the gap thermal resistance. The sensor probe can be screwed into the sensor mount. A total of four (or more) interlocking segments provides sufficient thermal isolation from a cryogenic substrate to prevent ice buildup on the sensor.