Gas Sensor Element Conducting Section Porosity Control
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Solution Overview
Problem
Existing gas sensors face accuracy deterioration due to external gases entering the sensor element and reaching the inner electrode, which affects the detection of specific gas concentrations.
Innovation Solution
The sensor element incorporates a conducting section with a specific porosity and thickness ratio (Rp/Dc ≤ 145%/mm) for the outer conducting section, which reduces gas entry through the inner conducting section or gaps, thereby minimizing the likelihood of gas reaching the inner electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lead structure is simplified for ease of manufacture, then manufacturing complexity is reduced, but gas may enter through gaps between the lead and element body, deteriorating detection accuracy
Solution Approach 1:
The patent introduces a covering portion as an intermediary component between the lead and the element body. This covering portion seals the gap between the lead and element body, preventing gas from entering through the gap, while still allowing the lead to be electrically connected to the inner electrode. The covering portion acts as a mediator that maintains both ease of manufacture and detection accuracy.
Solution Approach 2:
The covering portion is implemented as a thin-walled structure that conforms to the gap between the lead and element body. This thin film approach provides effective gas sealing while maintaining manufacturing simplicity and electrical connectivity.
2Measurement precision
If the outer conducting section thickness is increased to prevent gas entry, then detection accuracy is improved, but the porosity-to-thickness ratio decreases, potentially affecting gas permeability needed for detection
Solution Approach 1:
The patent applies different structural characteristics to different regions of the outer conducting section. The covering portion has a controlled porosity-to-thickness ratio that provides gas sealing where needed, while other portions maintain appropriate porosity for gas detection. This local differentiation allows simultaneous achievement of detection accuracy and gas permeability.
Solution Approach 2:
The outer conducting section utilizes porous material structure with controlled porosity. The covering portion has reduced porosity or increased thickness to prevent gas entry, while maintaining overall gas permeability for detection function. The porous structure allows selective gas transmission based on the specific porosity-to-thickness ratio.
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
This configuration effectively reduces the likelihood of accuracy deterioration in specific gas concentration detection by minimizing gas entry into the sensor element, as demonstrated through experiments and analyses.
Implementation Method 1
an element body including an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
letting a porosity be Rp [%] and a thickness be Dc [mm], a covering portion of the outer conducting section that covers the inner conducting section satisfies Rp/Dc≤145%/mm
Data Source
AI summary
A sensor element configured to detect a concentration of a specific gas in a measurement-object gas, the sensor element includes an element body having a front end, a rear end and a peripheral face; an inner electrode disposed inside the element body; and a conducting section including an inner conducting section and an outer conducting section, the outer conducting section including a connector electrode disposed at a part of the peripheral face that is near the rear end, the outer conducting section further including a segment disposed on the peripheral face and/or a segment disposed on the peripheral face and exposed to an outside of the sensor element, the outer conducting section being electrically continuous with the inner conducting section. Letting a porosity be Rp [%] and a thickness be Dc [mm], a covering portion of the outer conducting section that covers the inner conducting section satisfies Rp/Dc≤145%/mm.