Movable Support Structure for Thermal Stress Mitigation in Temperature Sensors
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Solution Overview
Problem
High-temperature sensors, such as exhaust gas temperature sensors, face issues with excessive compressive and tensile stresses due to high heating and cooling gradients, leading to damage of internal components and conductors, which reduces their lifespan and reliability.
Innovation Solution
A temperature sensor design featuring a mineral-insulated supply line, a bottomed metal tube with a movable support structure that decouples the temperature sensing element, allowing axial movement to mitigate stress, and a potting material with similar thermal expansion properties to reduce frictional forces, thereby minimizing damage from thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the temperature sensing element is fixedly secured in the bottomed metal tube, then the structural stability is improved, but the wire connection suffers excessive stress from thermal expansion differences leading to conductor damage
Solution Approach 1:
The support structure is made movable within the bottomed metal tube, allowing it to dynamically adjust its position in response to thermal expansion and contraction. This dynamic capability enables the system to accommodate temperature-induced dimensional changes without generating excessive stress on the wire connections, thereby maintaining both structural stability and connection reliability throughout the operating temperature range.
Solution Approach 2:
The system is divided into separable components: the bottomed metal tube, the movable support structure, and the wire connections. This segmentation allows each component to respond independently to thermal stresses - the support structure can move relative to the tube while the wire connections remain relatively stress-free, preventing conductor damage while maintaining overall structural integrity.
2Reliability
If the support structure is made movable to reduce stress, then the wire connection reliability is improved, but the manufacturing precision and assembly complexity increase
Solution Approach 1:
The friction coefficient between the support structure and the bottomed metal tube is carefully controlled by selecting materials with appropriate surface properties. By optimizing this friction parameter, the support structure maintains sufficient engagement to prevent excessive movement while allowing enough freedom to accommodate thermal expansion. This parameter optimization enables reliable wire connections without requiring extremely tight manufacturing tolerances or complex assembly procedures.
3Stability of the object's composition
If high friction material is used between support structure and metal tube, then the support structure is firmly held, but the wire connection suffers greater stress during thermal cycling
Solution Approach 1:
The support structure is designed with controlled movability rather than being completely fixed or completely free. The friction between the support structure and metal tube is optimized to allow the support structure to move just enough to accommodate thermal expansion differences, preventing excessive stress buildup in the wire connections while maintaining sufficient stability to prevent loose or unstable positioning during operation.
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 effectively reduces stress on wire connections, increasing the lifespan and reliability of high-temperature sensors by limiting compressive and tensile forces, ensuring consistent thermal contact and reducing wear from friction, thus enhancing their durability in fluctuating temperature environments.
Implementation Method 1
Due to the different coefficients of thermal expansion (CTE) of the material of the bottomed metal tube and the connection leads and the temperature difference between the bottomed metal tube and the connections leads during rapid temperature changes of the medium to be measured, the temperature sensing element moves in axial direction of the bottomed metal tube in the bottomed metal tune.
Implementation Method 2
The potting material has similar thermal expansion properties to reduce frictional forces, thereby minimizing damage from thermal cycling.
Implementation Method 3
The forces acting on the connection leads are now limited to the frictional forces between the temperature sensing element and the bottom metal tube.
Data Source
AI summary
A temperature sensor including a mineral-insulated supply line, a bottomed metal tube and a temperature sensing element secured in a support structure. An open end part of the bottomed metal tube is connected mechanically to the mineral-insulated supply line. A wire connection mechanically and electrically couples the temperature sensing element to the mineral-insulated supply line. The support structure is moveable in axial direction of the bottomed metal tube in a bottom end part of the bottomed metal tube.