SCR Reductant Dosing Error Diagnosis via Flow Feedback

Solution Overview

Problem

Aftertreatment systems for internal combustion engines face challenges in diagnosing errors in reductant dosing systems, such as stuck open or closed dosing modules, blockages, and leakages, which affect the efficiency of selective catalytic reduction (SCR) processes, leading to inadequate NOx emission reduction.

Innovation Solution

A diagnostic method and system that utilize a controller to access commanded and estimated flow data, calculate percentage error values, and determine specific error types based on predetermined thresholds, indicating issues like stuck closed, partial blockage, stuck open, or leakage errors in the dosing module or pressure lines, allowing for targeted corrective actions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reductant dosing system is used to introduce reductant into the exhaust gas flow for SCR process, then NOx emission reduction is achieved, but errors such as stuck open, stuck closed, blockage, or leakage may occur in the dosing module or pressure lines

Engineering Contradiction:

ImproveSCR process efficiencyVSAvoiddosing system errors

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system continuously monitors the actual reductant flow rate and compares it against the commanded flow rate to generate feedback signals. This feedback mechanism enables real-time detection of dosing errors by calculating percentage error values and comparing them against predetermined thresholds, allowing the controller to identify stuck open, stuck closed, blockage, or leakage conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical diagnostic methods with an electronic control system that uses sensors to measure flow rates and processes data through a controller. This substitution of mechanical monitoring with electronic sensing and computation enables more precise and reliable error detection in the reductant dosing system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the dosing module or pressure lines develop errors (stuck open, stuck closed, blockage, leakage), then reductant flow is affected, but diagnosing these errors becomes difficult without proper monitoring systems

Engineering Contradiction:

Improveerror diagnosis capabilityVSAvoiddosing error detection

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system continuously monitors the actual reductant flow rate and compares it against the commanded flow rate to generate feedback signals. This feedback mechanism enables real-time detection of dosing errors by calculating percentage error values and comparing them against predetermined thresholds, allowing the controller to identify stuck open, stuck closed, blockage, or leakage conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The controller acts as an intermediary between the dosing module and the monitoring system. It processes sensor data, calculates flow rate comparisons, determines percentage errors, and identifies error conditions. This intermediary function simplifies the diagnostic process by centralizing the analysis and interpretation of dosing system performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If no diagnostic monitoring is implemented, then system complexity is low, but error identification and timely maintenance are compromised

Engineering Contradiction:

Improvemonitoring system structureVSAvoidmaintenance response time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The system continuously monitors the actual reductant flow rate and compares it against the commanded flow rate to generate feedback signals. This feedback mechanism enables real-time detection of dosing errors by calculating percentage error values and comparing them against predetermined thresholds, allowing the controller to identify stuck open, stuck closed, blockage, or leakage conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary monitoring and error detection before failures can affect SCR process performance. By continuously comparing actual versus commanded flow rates and identifying errors early through percentage error analysis, the system enables timely maintenance actions that prevent degradation of emissions control effectiveness.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9664092B2Diagnosing system for reductant dosing system

Publication Date: 2017.05.30 CUMMINS EMISSION SOLUTIONS INC

AI summary

An SCR system may include a controller configured to diagnose errors with a dosing system. The controller may control a pump to compensate for a loss in pressure when dosing reductant and may maintain the pressure as close to a target pressure by modifying a parameter affecting the operation of the pump. The modification of the parameter may be used to determine an estimated flow feedback. The controller may use the estimated flow feedback data and commanded dosing amount data to calculate a percentage error in response to and using an integrated commanded flow and an integrated estimated flow feedback to detect errors of the dosing system. The errors may include an injector stuck closed error, a blocked pressure line error, a partial blockage of a pressure line or injector error, an injector stuck open error, a disconnected pressure line error, a leakage of a pressure line or injector error.