Ammonia Sensor Element with Dual Mixed-Potential Cells
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Solution Overview
Problem
Ammonia sensor elements face challenges in withstanding harsh vehicle exhaust gas environments and ensuring sufficient strength and poisoning resistance, particularly due to the low melting point of Au-based detection electrodes, which complicates the formation of effective protection layers through low-temperature sintering or thermal spraying.
Innovation Solution
The use of ammonia sensor elements with two mixed-potential-type ammonia detection cells, where the first and second detection electrodes have different metal compositions, including alloys with higher melting points than Au, such as Au-Pt and Au-Pd, allowing for high-temperature sintering and enhanced protection layer strength and poisoning resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection layer is formed by low-temperature sintering or thermal spraying on Au-based detection electrodes, then the electrode material is protected from water and poisoning substances, but the protection layer lacks sufficient strength and poisoning resistance due to the low melting point of Au
Solution Approach 1:
The patent changes the melting point parameter of the detection electrode by alloying Au with Pt or Pd, which have higher melting points. This allows the protection layer to be formed by high-temperature sintering, ensuring sufficient strength and poisoning resistance while maintaining the electrode's catalytic activity for ammonia detection
Solution Approach 2:
The patent uses composite materials by creating Au-Pt or Au-Pd alloy detection electrodes. These composite materials combine the low melting point and catalytic activity of Au with the high melting point and strength of Pt or Pd, enabling both effective protection layer formation and maintained detection performance
2Measurement precision
If a single ammonia detection cell is used, then the sensor structure is simple, but accurate separation and detection of ammonia from NOx in exhaust gas cannot be achieved
Solution Approach 1:
The patent divides the detection system into two separate ammonia detection cells, each with detection electrodes having different metal compositions. This segmentation allows each cell to respond differently to ammonia and NOx, enabling accurate separation and quantification of ammonia concentration in the exhaust gas through differential measurement
Solution Approach 2:
The patent applies local quality by giving each detection electrode a specific metal composition tailored to its detection function. The first detection electrode has one metal composition optimized for certain detection characteristics, while the second has another composition optimized for complementary characteristics, enabling differentiated response to ammonia and NOx
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 approach enables accurate ammonia detection from NOx in exhaust gases while ensuring the protection layer's strength and resistance, ensuring reliable performance in harsh environments.
Implementation Method 1
two mixed-potential-type ammonia detection cells that respectively include first and second ammonia detection electrodes
Implementation Method 2
a protection layer is optionally formed on a detection electrode of the ammonia sensor element so as to protect the detection electrode from water and poisoning substance
Implementation Method 3
the metal composition of the first ammonia detection electrode contains a metal having a melting point higher than that of Au and capable of alloying with Au
Data Source
AI summary
Disclosed is an ammonia sensor element for detecting ammonia in a gas under measurement, including two mixed-potential-type ammonia detection cells that respectively include first and second ammonia detection electrodes. The first ammonia detection electrode has a metal composition containing Au as a predominant component. The second ammonia detection electrode has a metal composition containing Au as a predominant component. The metal compositions of the first and second ammonia detection electrodes are different from each other.