SCR Assembly Fault Detection Using Exhaust Pressure Signals
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Solution Overview
Problem
Conventional selective catalytic reduction systems in internal combustion engines face issues such as build-up of solids in the exhaust pipes and spray modules, leading to restricted gas flow, increased backpressure, ammonia release, and elevated NOx output, which are not efficiently detected and addressed.
Innovation Solution
A computer-implemented method using upstream pressure information and pressure difference information to determine faults in the selective catalytic reducer assembly, including models to calculate expected pressures and differences, enabling detection of clogging or flow restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If selective catalytic reduction is used to convert NOx, then NOx reduction efficiency is improved, but solid build-up in exhaust pipes and spray modules occurs leading to flow restriction and increased backpressure
Solution Approach 1:
The system performs preliminary detection of fault conditions by monitoring pressure differences and upstream pressure changes before solid build-up severely impacts exhaust flow. This early detection allows for preventive maintenance actions to be taken before reliability deteriorates significantly.
Solution Approach 2:
The system implements continuous feedback monitoring of pressure parameters (pressure difference across DPF and upstream pressure changes) to detect deviations from normal operation. This feedback mechanism enables real-time identification of flow restriction conditions caused by solid build-up in the SCR assembly.
2Object-generated harmful factors
If more urea is released into the exhaust stream, then NOx conversion is improved, but solid build-up near spray modules increases causing flow restriction
Solution Approach 1:
The system replaces direct mechanical inspection of the SCR assembly for solid build-up with a pressure-based detection system. By monitoring pressure differences and upstream pressure changes, the system can infer clogging conditions without physical access to the SCR components, simplifying the detection mechanism.
Solution Approach 2:
The system uses pressure measurements as an intermediary parameter to indirectly detect solid build-up in the SCR assembly. Instead of directly measuring solid accumulation, the system monitors the effect of clogging on exhaust flow pressure, using pressure as a mediator to detect the underlying problem.
3Measurement precision
If fault detection is implemented using pressure monitoring, then early detection capability is improved, but system complexity increases
Solution Approach 1:
The pressure sensors serve multiple functions: they monitor both the pressure difference across the DPF and the upstream pressure changes. This multi-functionality allows a single sensing system to detect multiple fault conditions (DPF clogging and SCR assembly clogging) without requiring separate dedicated sensors for each function.
Solution Approach 2:
The system uses existing pressure sensors in the exhaust aftertreatment system for fault detection purposes. Rather than adding dedicated detection equipment, the system leverages the self-service capability of existing pressure measurements to identify faults, minimizing additional system complexity.
Data Source
AI summary
A computer-implemented method for detecting a fault in a selective catalytic reducer assembly of an internal combustion engine system includes: receiving, by processing circuitry of a computer system, upstream pressure information indicative of an exhaust gas pressure at a position upstream the diesel particulate filter, as seen in an intended direction of flow from the internal combustion engine to the diesel particulate filter; receiving, by the processing circuitry, pressure difference information indicative of a pressure difference across the diesel particulate filter; and using, by the processing circuitry, the upstream pressure information and the pressure difference information to determine whether or not a fault has occurred in the exhaust selective catalytic reducer assembly.