Temperature Sensor Thermal Isolation via Segmented Housing
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Solution Overview
Problem
Conventional temperature sensors face reduced responsiveness due to heat transfer from the heat-sensitive element through the insulating support and insulation sheath, leading to increased response time in measuring fluid temperatures.
Innovation Solution
A temperature sensor design featuring a housing tube with a distal accommodation portion having a smaller outside diameter than the sheath accommodation portion, accommodating at least half of the insulating support, which reduces heat transfer by minimizing temperature differences between the heat-sensitive element and the insulating support, and using materials like alumina for the insulating support to further restrain heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the heat-sensitive element, insulating support and insulation sheath are disposed in a thermally coupled condition, then the structural compactness is improved, but the responsiveness deteriorates due to heat transfer from the heat-sensitive element through the insulating support and insulation sheath
Solution Approach 1:
The housing tube is divided into two portions: a distal accommodation portion with a smaller outside diameter that accommodates the insulating support, and a sheath accommodation portion with a larger outside diameter that accommodates the insulation sheath. This segmentation creates thermal isolation by limiting the thermal coupling between components, thereby reducing heat transfer from the heat-sensitive element through the insulating support and insulation sheath, while maintaining structural compactness.
2Loss of time
If the insulating support has a large volume, then the heat transfer restraint is improved, but the device complexity increases
Solution Approach 1:
The insulating support is nested within the distal accommodation portion of the housing tube, which has a smaller outside diameter. This nesting arrangement allows the insulating support to have a sufficiently large volume to restrain heat transfer while being compactly integrated into the housing structure, avoiding excessive device complexity.
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 design enhances responsiveness by reducing heat transfer, allowing the temperature sensor to quickly measure fluid temperatures with improved accuracy and efficiency.
Implementation Method 1
a heat-sensitive portion whose electric characteristic varies with temperature... a thermistor sintered-body whose resistance varies with temperature
Implementation Method 2
an insulating support in contact with a rear end of the heat-sensitive element... restraining heat transfer from the heat-sensitive element through the insulating support
Data Source
AI summary
A temperature sensor (100) includes a heat-sensitive element (21) having a thermistor sintered-body (22), an insulating support (31), an insulation sheath (41) and a housing tube (11). The insulating support (31) is in contact with the rear end of the heat-sensitive element (21) and the insulation sheath (41) is in contact with the rear end of the insulating support (31). The housing tube (11) accommodates the heat-sensitive element (21), the insulating support (31) and the insulation sheath (41). The housing tube (11) includes a sheath accommodation portion (14) which accommodates the insulation sheath (41) and a distal accommodation portion (13). The distal accommodation portion (13) is located toward the distal end of the housing tube (11) with respect to the sheath accommodation portion (14), is smaller in outside diameter than the sheath accommodation portion (14), and accommodates at least half of the insulating support (31) as measured from the axially distal end of the insulating support (31).