High-Temperature Sensor Element with Ceramic Encapsulation
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Solution Overview
Problem
High-temperature sensor elements face challenges in maintaining accuracy and durability in oxidizing environments while being cost-effective, as existing solutions often degrade quickly and are not robust enough to withstand high temperatures for extended periods.
Innovation Solution
A high-temperature sensor element comprising a thermistor element with electro-conductive bridges connected to a ceramic-based contacting element, sealed with a ceramic or glass encapsulation compound, using materials like aluminum oxide and metallic conductors, and assembled using firing or welding processes to ensure stability and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sensor elements are used in high-temperature environments, then initial temperature measurement function is provided, but they degrade quickly and lose reliability
Solution Approach 1:
The patent employs a composite structure consisting of a ceramic base body (aluminum oxide or aluminum nitride), metallic conductor lines, a thermistor element with specific composition, and a glass encapsulation compound. This composite material system provides high-temperature stability, oxidation resistance, and mechanical strength, enabling the sensor to maintain reliability in environments up to 1000°C for extended periods
Solution Approach 2:
The glass encapsulation compound creates a hermetic seal around the thermistor element and conductor lines, isolating them from the oxidizing atmosphere. This protective barrier prevents oxygen from reaching and degrading the metallic components and thermistor material, thereby extending service life in high-temperature environments
2Temperature
If robust materials and sealing processes are used to withstand high temperatures, then temperature resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent integrates multiple functions into unified components: the ceramic base body serves as both mechanical support and electrical insulation, the glass encapsulation provides both hermetic sealing and thermal protection, and the conductor lines are directly applied to the ceramic surface. This merging of functions reduces the number of separate components and assembly steps compared to conventional designs
Solution Approach 2:
The patent replaces complex mechanical assembly operations with firing and sintering processes. Conductor lines are applied via screen printing and bonded through firing, eliminating the need for mechanical fastening. The glass encapsulation is formed by melting and sealing, replacing complex mechanical sealing mechanisms. These thermal processing steps simplify the overall manufacturing process while achieving high-temperature performance
3Stability of the object's composition
If expensive high-temperature stable materials are used, then temperature stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent utilizes the temperature-dependent electrical resistance characteristics of the thermistor element (NTC or PTC) to achieve temperature measurement without requiring expensive active sensing materials. By carefully selecting the thermistor composition and geometry, stable temperature characteristics are achieved through parameter optimization rather than using costly exotic materials
Solution Approach 2:
The patent employs homogeneous ceramic materials (aluminum oxide or aluminum nitride) with consistent properties throughout the base body, ensuring uniform thermal and electrical characteristics. The glass encapsulation compound is also formulated to have homogeneous composition and matched thermal expansion properties, reducing the need for expensive gradient materials or complex composite structures
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 provides a robust, cost-effective high-temperature sensor element with stable temperature characteristics and resistance, maintaining accuracy and durability in high-temperature, oxidizing environments without significant degradation.
Implementation Method 1
The wire parts are preferably fixed on the contact areas of the NTC element and the conductor lines of the contacting element by a fired conductive compound or by a welding process or by a bonding process
Implementation Method 2
The wire parts are preferably fixed on the contact areas of the NTC element and the conductor lines of the contacting element by a fired conductive compound or by a welding process or by a bonding process
Implementation Method 3
the NTC element and a part of the contacting element adjacent to the NTC element are hermetically sealed by a surrounding encapsulation compound
Implementation Method 4
The abbreviation NTC stands for Negative Temperature Coefficient Thermistor. These are therefore sensor elements which, at least within a limited temperature interval, have a negative temperature coefficient of the electrical resistance
Data Source
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AI summary
A high-temperature sensor element includes at least one thermistor element having at least two contact areas and one contacting element including an isolating ceramic base body and at least two conductor lines. The contact areas of the thermistor element are connected to the conductor lines of the contacting element by an electro-conductive bridge. A process for assembling a sensor element is also described in which an thermistor element is connected by a temperature resistant junction to a contacting element, and in which the thermistor element and part of the contacting element adjacent to the thermistor element are sealed by a encapsulation compound.