Gas Sensor Solid Electrolyte Interface Porous Layer
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Solution Overview
Problem
Conventional gas sensors lack measures to facilitate the prompt passage of oxygen ions between the measurement and reference electrodes via the solid electrolyte, hindering their responsiveness and accuracy in detecting imbalances between cylinders of an internal combustion engine.
Innovation Solution
The gas sensor design minimizes interface capacitance and resistance between the solid electrolyte and electrodes, allowing for easier oxygen ion movement by optimizing the film thickness and material properties of the measurement and reference electrodes, ensuring that the interface capacitance is no more than 150 μF and interface resistance is 80Ω or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional gas sensor design is used, then the structure is simple, but the responsiveness is poor due to slow oxygen ion passage
Solution Approach 1:
The patent applies local quality by creating a porous layer only at the interface between the solid electrolyte and electrodes, rather than modifying the entire sensor structure. This localized porous structure facilitates oxygen ion transport where it is most needed while keeping the rest of the sensor design simple.
Solution Approach 2:
The patent introduces a porous layer with controlled porosity (30-70%) at the interface between the solid electrolyte and electrodes. This porous structure provides pathways for oxygen ions to pass through more easily, improving responsiveness without requiring complete structural redesign.
2Measurement precision
If conventional gas sensor design is used, then manufacturing is easy, but measurement precision is insufficient for detecting cylinder imbalances
Solution Approach 1:
The patent changes physical parameters of the interface region, specifically controlling porosity (30-70%) and thickness (1-10 μm) of the porous layer. These parameter adjustments optimize oxygen ion transport to improve measurement precision for detecting small cylinder imbalances while maintaining manufacturability through standard ceramic processing.
Solution Approach 2:
The patent incorporates the porous layer formation as a preliminary step in the manufacturing process, creating the optimized interface structure before final assembly. This preliminary action ensures measurement precision is built into the sensor during manufacturing rather than requiring post-processing adjustments.
3Reliability
If the solid electrolyte interface is not optimized, then manufacturing is simple, but oxygen ion conductivity is poor
Solution Approach 1:
The patent introduces a porous layer at the solid electrolyte interface to enhance oxygen ion conductivity. The porous structure creates additional pathways for ion transport, improving reliability without requiring complex multi-layer interfaces or alternative materials.
Solution Approach 2:
The patent applies the porous structure locally only at the critical interface region between the solid electrolyte and electrodes, rather than throughout the entire sensor. This localized approach improves oxygen ion conductivity where needed while keeping the overall device structure relatively simple.
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 enhances the responsiveness and accuracy of the gas sensor in detecting oxygen concentration differences, thereby improving the measurement of air-fuel ratio imbalances between engine cylinders.
Implementation Method 1
The solid electrolyte has oxygen ion conductivity
Data Source
AI summary
A gas sensor is provided which has improved responsiveness and is capable of improving accuracy in measurement of an imbalance between cylinders. The gas sensor includes a solid electrolyte having oxygen ion conductivity, a measurement electrode mounted on one principal surface of the solid electrolyte and is exposed to measurement gas, and a reference electrode mounted on the other principal surface of the solid electrolyte and exposed to reference gas A. Interface capacitance between crystal particles constituting the solid electrolyte is not more than 150 μF. Interface resistance between the crystal particles constituting the solid electrolyte and each of the measurement electrode and the reference electrode is not more than 80 Ω. The measurement electrode has a film thickness t1 of 2 to 8 μm.