Real-Time NOx Adsorption Catalyst Diagnosis via Lambda Difference
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Solution Overview
Problem
Current NOx-adsorption catalysts (NACs) in engine aftertreatment systems lose effectiveness over time, leading to reduced NOx compound storage capacity and increased emissions, with no direct measurement available for their degradation, necessitating more frequent regenerations and lacking real-time diagnostic capabilities to meet stringent emissions regulations.
Innovation Solution
A system and method for real-time diagnosis of NACs using modules such as a NAC operation module, exhaust conditions module, engine conditions module, and integration module, which verify steady-state operating conditions, calculate lambda differences, and determine transition areas to set a NAC function indicator, enabling diagnosis without excessive computer power and using commonly available sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time diagnosis of NAC is implemented using complex measurement systems, then diagnostic accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces lambda sensors as intermediary measurement devices that indirectly assess NAC storage capacity by measuring oxygen concentration in exhaust gas. Instead of directly measuring NOx storage, the system uses oxygen sensors upstream and downstream of the NAC to detect lambda values, which serve as proxies for NAC functionality. This intermediary approach enables diagnosis without requiring complex direct measurement equipment.
Solution Approach 2:
The patent replaces complex mechanical or chemical measurement systems with electronic sensor-based detection. By using lambda sensors and electronic control units to monitor exhaust gas composition and calculate diagnostic parameters, the system substitutes sophisticated physical measurement apparatus with simpler electronic detection methods, reducing overall system complexity while maintaining diagnostic capability.
2Measurement precision
If direct measurement of NAC storage capacity is implemented, then diagnostic accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent makes existing lambda sensors serve multiple functions: they continue to provide exhaust gas composition data for engine control while simultaneously enabling NAC diagnostic capabilities. This multi-functionality allows the same sensors to be used for both operational control and degradation detection, eliminating the need for separate dedicated measurement equipment and simplifying manufacturing.
Solution Approach 2:
The diagnosis system utilizes data already being collected by the engine control system for normal operation. The lambda sensors and control unit that exist for engine management purposes are leveraged to provide NAC diagnostic information, allowing the system to diagnose itself without requiring additional independent measurement infrastructure, thereby reducing manufacturing complexity.
3Object-generated harmful factors
If frequent regenerations are performed to compensate for NAC degradation, then emissions are reduced, but productivity and fuel efficiency decrease
Solution Approach 1:
The patent implements preliminary diagnosis that detects NAC degradation trends before they lead to complete failure or excessive emissions. By monitoring lambda differences and calculating diagnostic parameters in real-time, the system can predict when NAC performance will deteriorate to problematic levels, allowing for proactive maintenance scheduling that optimizes the balance between emissions control and engine productivity.
Solution Approach 2:
The patent establishes a feedback loop where continuous monitoring of exhaust gas composition provides real-time information about NAC storage capacity. This feedback enables dynamic adjustment of regeneration timing and strategy, allowing the system to perform regenerations only when necessary based on actual NAC condition rather than on fixed schedules, thereby maintaining emissions control while minimizing impact on productivity.
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
Enables real-time diagnosis of NACs, allowing for timely mitigating responses to degradation, such as increased regeneration frequency or emissions control schemes, thereby reducing emissions and meeting regulatory requirements.
Implementation Method 1
these catalysts adsorb NOx compounds and oxygen while an engine runs lean, and desorb and reduce the NOx compounds in a regeneration cycle while the engine runs rich
Implementation Method 2
these catalysts adsorb NOx compounds and oxygen while an engine runs lean, and desorb and reduce the NOx compounds in a regeneration cycle while the engine runs rich
Implementation Method 3
The catalytic materials in the NAC age over time and become less effective. Specifically, the NAC will lose capacity to store NOx compounds and oxygen
Data Source
AI summary
An apparatus, system, and method are disclosed for real-time diagnosis of a NOx-adsorption catalyst (NAC). The method includes verifying that a NAC temperature exceeds a threshold, determining that the NAC is in a steady-state operating condition, and surveying a first oxygen sensor upstream of the NAC and a second oxygen sensor downstream of the NAC. The method further includes calculating a lambda difference between the first and second oxygen sensors, and interpreting a NAC regeneration indicator. The method further includes determining a lean-to-rich transition and a rich-to-lean transition area based on the lambda difference and the regeneration indicator. The method concludes with setting a NAC function indicator according to the lean-to-rich transition area and the rich-to-lean transition area.