Ammonia Sensor Catalyst Diagnosis via Transmission Shifts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current catalyst deterioration diagnosis methods for three-way catalysts in gasoline engines face inaccuracies due to limited evaluation of precious metal deterioration, sensor measurement errors, and restrictive diagnostic conditions, particularly affecting oxygen storage capacity and NOx removal performance.
Innovation Solution
A catalyst deterioration diagnosis system utilizing a gas sensor with sensitivity to ammonia, which monitors temporary increases in detection values during transmission shifts to accurately assess catalyst deterioration, reducing interference from NOx and allowing for more frequent and accurate diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the OSC method is used to diagnose catalyst deterioration, then oxygen storage capacity can be evaluated, but measurement accuracy is reduced due to sensor errors and inability to evaluate precious metal deterioration
Solution Approach 1:
The patent uses transmission shift events as an intermediary trigger to initiate ammonia detection. The transmission controller detects shift events and signals the ECU to start monitoring, which in turn activates the ammonia sensor reading. This intermediary mechanism allows frequent diagnostics without requiring complex continuous monitoring systems, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The system utilizes existing transmission shift events (which occur naturally during normal driving) to trigger catalyst diagnostics. Instead of requiring a separate diagnostic trigger or continuous monitoring, the system self-activates diagnostics using the transmission's own operational data, eliminating the need for additional complex triggering mechanisms while maintaining diagnostic accuracy.
2Measurement precision
If traditional O2 sensors are used for diagnosis, then oxygen storage capacity can be monitored, but NOx removal performance cannot be directly assessed
Solution Approach 1:
The patent changes the detection parameter from oxygen concentration (O2 sensors) to ammonia concentration (ammonia sensor). This parameter change enables direct assessment of NOx removal performance, as ammonia is a byproduct of NOx reduction reactions. The ammonia sensor directly measures the effectiveness of the catalyst's NOx removal function, providing both precision and versatility in diagnosing different catalyst performance aspects.
3Measurement precision
If continuous monitoring is implemented, then diagnostic accuracy improves, but device complexity and energy consumption increase
Solution Approach 1:
The patent implements periodic ammonia detection triggered by transmission shift events rather than continuous monitoring. The ECU is configured to read the ammonia sensor value only when a shift event is detected by the transmission controller. This periodic action maintains diagnostic accuracy by capturing catalyst performance at multiple time points while significantly reducing energy consumption compared to continuous monitoring, as the sensor is activated only at discrete intervals during normal driving.
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
The system enables high-accuracy catalyst deterioration diagnosis from the viewpoint of ammonia generation, providing more direct and frequent assessments compared to traditional methods, with improved accuracy and reduced interference, suitable for passive OBD and various engine states.
Implementation Method 1
a gas sensor having sensitivity to ammonia that outputs a detection value corresponding to a component of an exhaust gas that has passed through the catalyst
Implementation Method 2
a catalyst into which an exhaust gas from an internal combustion engine is introduced
Data Source
AI summary
A catalyst deterioration diagnosis method is a method for a system. The system includes a stepped transmission or a continuously variable transmission connected to an internal combustion engine, a catalyst into which an exhaust gas from the internal combustion engine is introduced, and a gas sensor having sensitivity to ammonia that outputs a detection value corresponding to a component of an exhaust gas that has passed through the catalyst. The catalyst deterioration diagnosis method includes the following steps. Monitoring of temporary increase of a detection value of the gas sensor is started, and thereby a temporarily increased amount of the detection value of the gas sensor is acquired. The monitoring is started when upshifting of the stepped transmission or pseudo-upshifting of the continuously variable transmission is performed. Whether or not the temporarily increased amount is larger than a threshold amount is determined.