Hermetic High-Temperature Sensor Unit With Glass-Ceramic Sealing
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Solution Overview
Problem
Existing sensor elements in harsh environments with high temperatures and aggressive media suffer from contamination, leading to measurement drift due to lack of hermetic sealing.
Innovation Solution
A hermetically sealed unit design with a housing that integrates an electrical functional element, using a non-conducting substrate and electrically conductive elements, sealed with a glass or glass ceramic insulating material, forming a hermetic bond to protect the element from external contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective tube housing is used for sensor elements in high-temperature environments, then the sensor element is protected from mechanical damage, but the housing is not hermetically sealed allowing corrosive gases to penetrate and cause measurement drift
Solution Approach 1:
The patent changes the material parameter from conventional metals to glass or glass-ceramic materials that can be hermetically sealed. The sealing is achieved by fusing the glass material to the sensor element and housing at high temperatures, creating a hermetic barrier that prevents gas penetration while maintaining mechanical strength in corrosive environments above 700°C.
Solution Approach 2:
The patent employs composite construction by combining the sensor element with glass or glass-ceramic sealing material. This composite structure integrates the electrical functional element with the hermetic seal, creating a unified assembly that provides both mechanical protection and hermetic sealing against corrosive gases at high temperatures.
2Reliability
If glass packing is used to hold the measuring probe in place, then electrical insulation is provided, but customary glass materials are unsuitable for temperatures above 700°C
Solution Approach 1:
The patent changes the glass material parameters by selecting specific glass compositions and applying appropriate heat treatment processes. The glass or glass-ceramic material is chosen and processed to have a softening point and thermal stability exceeding 700°C, while maintaining its electrical insulation properties. This allows the glass to serve both as an insulating material and a high-temperature resistant sealing material.
3Ease of operation
If the sensor element is exposed to the local environment for external access, then connection is simplified, but contamination from corrosive substances causes impairment and drift in measured values
Solution Approach 1:
The patent divides the sensor element into two distinct sections: a first section that is hermetically sealed within the housing and protected from the environment, and a second section with connection wires or connection pads that remains externally accessible for electrical connection. This segmentation allows the sensitive measuring portion to be isolated from contaminants while maintaining ease of electrical access.
Solution Approach 2:
The hermetic seal acts as an intermediary barrier between the protected sensor element and the corrosive external environment. The glass or glass-ceramic sealing material provides this intermediate protective layer, allowing the sensor to function accurately in harsh environments while connection wires extend through the seal to provide external electrical access without exposing the sensitive elements to contamination.
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 hermetic seal with a helium leak rate of less than 1·10−5 mbar·l/sec, preventing contamination and ensuring accurate measurements by shielding the sensor from corrosive substances and mechanical stress.
Implementation Method 1
the insulating material has been fused onto the at least one electrical functional element, resulting in the formation of a physical and/or chemical bond at an interface therebetween
Implementation Method 2
a hermetic seal with a helium leak rate of less than 1·10−5 mbar·l/sec, preventing contamination and ensuring accurate measurements by shielding the sensor from corrosive substances
Data Source
AI summary
A unit for high-temperature for uses above 700° C. is provided. The unit includes a housing and an electrical functional element. The functional element has a non-conducting substrate, an electrically conductive element, and at least one connection wire or pad. The functional element has a first section, a second section, and a third section. The first section is within the housing and shielded from a local environment. The second section includes the at least one connection wire or pad and is accessible externally to the housing. The third section is between the first and second sections and is embedded in an electrically insulating material. The insulating material seals off the housing from the functional element. A physical and/or chemical bond at an interface between the insulating material and the functional element.