All-Ceramic Temperature Probe for 1200°C Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional temperature sensors, such as ceramic thermistor elements, have limited operating temperatures and delayed response times due to encapsulation materials, making them unsuitable for high-temperature applications and aggressive media, and resistance adjustment is difficult once encapsulated.
Innovation Solution
A temperature sensor design featuring multiple ceramic plates with NTC sensor elements embedded and sintered to form a ceramic body, providing all-ceramic encapsulation for robustness and short response times, along with adjustable resistance through connection cap machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor elements are coated with polymer or glass to protect against external influences, then mechanical stability and corrosion resistance are improved, but maximum operating temperature is limited to approximately 200°C for polymer and 500-700°C for glass
Solution Approach 1:
The patent changes the material parameter of the encapsulation from polymer or glass to ceramic material. This parameter change enables the sensor to withstand temperatures up to 1200°C while maintaining mechanical stability and corrosion resistance, as ceramic materials have inherently higher thermal stability and chemical inertness compared to polymer or glass coatings.
Solution Approach 2:
The patent uses a composite structure where a ceramic sensor element is encapsulated in a ceramic housing. This composite ceramic-ceramic construction provides both the high temperature resistance (up to 1200°C) and the mechanical stability required, overcoming the limitations of polymer or glass encapsulation while maintaining protective functions.
2Reliability
If sensor elements are housed in plastic or stainless steel casing with potting compounds to enable use in aggressive media, then protection against aggressive media is improved, but response time is delayed due to additional heat transfer and low thermal conductivity
Solution Approach 1:
The patent changes the encapsulation material from plastic or potting compounds to ceramic material. This parameter change dramatically improves thermal conductivity, enabling the sensor to respond quickly to temperature changes while still providing protection against aggressive media through the chemically inert ceramic housing.
Solution Approach 2:
The patent applies local quality by creating direct thermal contact between the ceramic sensor element and the external environment through strategically placed thermal contact surfaces on the ceramic housing, while maintaining protective encapsulation in other areas. This localized optimization of thermal contact minimizes heat transfer resistance without compromising overall protection.
3Manufacturing precision
If resistance is adjusted by mechanical processing such as trimming or grinding before encapsulation, then resistance tolerance is minimized, but adjustment after encapsulation is only possible to a limited extent
Solution Approach 1:
The patent performs resistance adjustment through mechanical processing (trimming or grinding) before the ceramic encapsulation is completed, during the green state when the ceramic is still soft. This preliminary action ensures precise resistance tolerance (±1% or better) is achieved before final encapsulation, eliminating the need for difficult post-encapsulation adjustments.
Solution Approach 2:
The patent introduces dynamic adjustability by allowing resistance fine-tuning after encapsulation through controlled heating that temporarily softens the ceramic material, enabling mechanical adjustment of the sensor element. This dynamic property allows post-manufacturing resistance adjustment while maintaining the sealed encapsulated structure.
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 all-ceramic encapsulation enables temperature sensors to operate stably at up to 1200°C with response times under three seconds, and resistance tolerances can be set to less than 1%, suitable for aggressive environments and precise temperature monitoring.
Implementation Method 1
ceramic negative temperature coefficient (NTC) thermistors
Implementation Method 2
The first, second, and third ceramic plates and the NTC sensor elements are sintered together to form a ceramic body
Data Source
Figure 1A~1F
Figure 1G~1J
Figure 2~3
AI summary
The invention relates to a temperature probe comprising two first ceramic plates, a second ceramic plate arranged between the first ceramic plates, and two third ceramic plates. Each of the two first ceramic plates comprises an opening in each in which an NTC sensor element is arranged. An electrode is arranged between the second ceramic plate and each of the first ceramic plates. The first and the second ceramic plates are arranged between the two third ceramic plates. An electrode is arranged between each third ceramic plate and a first ceramic plate. Each electrode electrically contacts an NTC sensor element. Each NTC sensor element is enclosed by ceramic plates. The first, the second and the third ceramic plates and the NTC sensor elements are sintered to form a ceramic body. The invention further relates to a method for producing a temperature probe.