Oxygen Sensor SCR Catalyst Deactivation Detection
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Solution Overview
Problem
Current methods for diagnosing selective catalyst reduction (SCR) catalyst deactivation in engine exhaust systems are costly due to the use of NOx/NH3 sensors, and existing systems struggle to reliably detect deactivation, leading to increased emissions of NOx and NH3.
Innovation Solution
Positioning an oxygen sensor downstream from the SCR catalyst to determine the oxygen storage capacity and extent of deactivation, allowing for reliable diagnosis and reduced emissions without the need for expensive NOx/NH3 sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NOx/NH3 sensors are positioned downstream from the SCR catalyst to measure breakthrough, then SCR catalyst deactivation can be detected, but vehicle manufacturing and maintenance costs increase
Solution Approach 1:
The patent replaces expensive NOx/NH3 sensors with a cheaper oxygen sensor that can be positioned downstream from the SCR catalyst. The oxygen sensor measures oxygen storage capacity changes that indirectly indicate SCR catalyst deactivation, providing a cost-effective solution that maintains detection reliability while reducing manufacturing and maintenance costs.
Solution Approach 2:
The patent uses oxygen storage capacity as an intermediary parameter to indirectly detect SCR catalyst deactivation. Instead of directly measuring NOx or NH3 breakthrough with expensive sensors, the system measures oxygen storage capacity changes which serve as a proxy indicator for catalyst health, thereby reducing sensor costs while maintaining detection capability.
2Reliability
If oxygen sensor is positioned downstream from SCR catalyst to measure oxygen storage capacity, then SCR catalyst deactivation can be reliably diagnosed, but the system complexity increases
Solution Approach 1:
The patent leverages the oxygen sensor's existing capability to measure oxygen storage capacity for a dual purpose: both monitoring exhaust gas composition and detecting SCR catalyst deactivation. This multi-functional use of the oxygen sensor avoids adding separate dedicated sensors, thereby reducing overall system complexity while maintaining reliable diagnosis capability.
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 reliable detection of SCR catalyst deactivation, reducing exhaust emissions and lowering vehicle manufacturing and maintenance costs by adjusting engine operations to mitigate NOx and NH3 breakthroughs.
Implementation Method 1
determining an oxygen storage capacity of the SCR catalyst based on a measurement of the oxygen sensor
Implementation Method 2
SCR catalysts can capture and mitigate NOx and NH3 breakthrough in the exhaust stream during transient fuel shutoff (TFSO) and engine start-stop events
Data Source
AI summary
Methods and systems are provided for operating an engine of a vehicle. In one example, a method may include positioning an oxygen sensor in an engine exhaust downstream from a selective catalytic reduction (SCR) catalyst, determining an oxygen storage capacity of the SCR catalyst based on a measurement of the oxygen sensor, and determining an extent of deactivation of the SCR catalyst based on the oxygen storage capacity.