Ammonia Sensor Deterioration Detection via DC Current Comparison
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Solution Overview
Problem
Existing ammonia sensors, particularly potential-difference-type sensors, face challenges in accurately determining deterioration due to poisoning by toxic substances in exhaust gases, which affects their performance and requires a more effective method for assessing sensor element degradation.
Innovation Solution
A deterioration determination apparatus for ammonia sensors that applies a DC voltage between the ammonia electrode and reference electrode to detect sensor currents at initial and subsequent use periods, comparing these currents to determine if deterioration has occurred, utilizing a potential-difference-type ammonia sensor with a solid electrolyte and a reference electrode to assess the ammonia element portion's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a potential-difference-type ammonia sensor is used to detect ammonia concentration in exhaust gases, then the sensor can operate in harsh exhaust environments, but the sensor suffers from poisoning by toxic substances which deteriorates its performance and measurement accuracy
Solution Approach 1:
The system performs preliminary action by measuring sensor current at an initial time during the initial period of use of the ammonia sensor, before significant deterioration occurs. This initial measurement serves as a baseline for later comparison to determine if deterioration has occurred, allowing early detection of performance degradation due to poisoning by toxic substances in exhaust gases
Solution Approach 2:
The system implements feedback by comparing the sensor current measured at evaluation time with the sensor current measured at initial time. This feedback mechanism enables continuous monitoring of sensor health and automatic determination of deterioration, allowing the system to compensate for or replace the sensor based on measured performance changes
2Duration of action of moving object
If the ammonia sensor is used for an extended period in harsh exhaust environments, then continuous monitoring is achieved, but deterioration occurs due to poisoning by toxic substances
Solution Approach 1:
The system establishes a baseline sensor current measurement during the initial period of use, before extended exposure to harsh exhaust environments causes significant deterioration. This preliminary measurement enables future comparison to detect when the sensor has deteriorated due to prolonged exposure to toxic substances
Solution Approach 2:
The system uses feedback by continuously monitoring sensor current and comparing it with the initial measurement. This feedback loop allows determination of whether deterioration has occurred after extended use, enabling timely replacement or compensation to maintain reliability over the sensor's service life
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 method allows for accurate determination of deterioration in the ammonia sensor element, enabling timely replacement and maintaining the sensor's effectiveness in detecting ammonia concentrations in exhaust gases, thereby improving the reliability of NOX reduction processes in vehicles.
Implementation Method 1
an ammonia element portion that includes a solid electrolyte, an ammonia electrode, and a reference electrode
Implementation Method 2
a first sensor current obtained when a direct-current (DC) voltage is applied between the ammonia electrode and the reference electrode
Data Source
AI summary
A deterioration determination apparatus is usable with an ammonia sensor that includes an ammonia element portion that includes, a solid electrolyte, an ammonia electrode, and a reference electrode. The deterioration determining apparatus compares a first evaluation value and a second evaluation value, and determines whether deterioration has occurred in the ammonia element portion of the ammonia sensor at an evaluation time or subsequent to the evaluation time. The first evaluation value is based on a first sensor current obtained when a DC voltage is applied between the ammonia electrode and the reference electrode of the ammonia element portion at an initial time that is during an initial use period of the ammonia sensor. The second evaluation value is based on a second sensor current obtained when the DC voltage is applied between the ammonia electrode and the reference electrode subsequent to the initial period of use of the ammonia sensor.