Laminated Solid Electrolyte Gas Sensor Water Intrusion Prevention
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Solution Overview
Problem
Conventional gas sensors for measuring NOx concentrations in combustion gases face challenges in preventing condensate water from entering the sensor element, which can lead to measurement accuracy deterioration due to contamination and clogging.
Innovation Solution
The gas sensor design incorporates horizontally-long slit openings on the forward end surface and a porous layer on the side surfaces to prevent water droplets from entering, with the porous layer positioned at least 2 mm from the forward end, ensuring that condensate water is absorbed and dispersed, thereby protecting the sensor element from contaminants and maintaining measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the opening size is increased to improve gas diffusion, then water droplets can enter the sensor element more easily
Solution Approach 1:
The patent applies a porous layer on the side surfaces of the sensor element. This porous structure allows gas molecules to diffuse through while the surface tension and capillary effects in the porous material prevent larger water droplets from entering, thus resolving the contradiction between gas diffusion efficiency and water droplet intrusion prevention.
Solution Approach 2:
The patent introduces a vertical dimension by positioning the porous layer at a specific distance (≥2mm) from the forward end surface. This spatial arrangement creates a protective zone that intercepts water droplets before they can reach the opening, allowing the opening to be optimized for gas diffusion without compromising against water intrusion.
2Object-affected harmful factors
If the porous layer is positioned close to the forward end to prevent water entry, then gas diffusion is hindered
Solution Approach 1:
The patent positions the porous layer in the vertical dimension at a distance of 2mm or more from the forward end surface, rather than placing it directly at the opening. This spatial separation allows gas to diffuse horizontally through the opening while water droplets falling vertically are intercepted by the porous layer, resolving the contradiction between water protection and gas diffusion.
3Productivity
If the opening area is increased to improve sensor response, then measurement precision deteriorates due to water contamination
Solution Approach 1:
The porous layer acts as a selective barrier that permits gas molecules to pass through while blocking water droplets. This allows the opening area to be optimized for fast sensor response without compromising measurement precision, as the porous layer prevents water contamination that would otherwise degrade accuracy.
Solution Approach 2:
The porous layer serves as an intermediary element between the opening and the sensor element interior. It mediates the interaction between gas and water, allowing beneficial gas diffusion while blocking harmful water intrusion, thus enabling both fast response and high precision measurements.
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 design effectively prevents condensate water from entering the sensor, reducing the risk of contamination and clogging, thereby maintaining the sensor's responsiveness and measurement accuracy over time.
Implementation Method 1
these water droplets are moved and absorbed into the porous layer to be dispersed inside the porous layer
Data Source
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AI summary
A laminated solid electrolyte gas sensor (100) for detecting a predetermined gas component in a measurement gas includes a sensor element in which an opening (10a) of a first gas inlet (10) and an opening (11a) of a second gas inlet (11) for introducing the measurement gas from an outside are provided at one end. The openings are elongated and substantially rectangular. A sum of sizes in a lateral direction of the openings is greater than or equal to 8 µm and less than or equal to 60 µm, and a sum of areas of the openings is greater than or equal to 0.02 mm2 and less than or equal to 0.1 mm2. The sizes in the lateral direction and the areas of the openings are set to be within a preferable range so that the water droplets attached on the forward end surface can be prevented from entering into the sensor element through the openings.