Reductant Injector Pressure Control for Engine Emissions
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Solution Overview
Problem
Monitoring the exhaust gas stream downstream of a selective catalytic reduction catalyst (SCR) introduces latency in reductant delivery systems, affecting dynamic responsiveness and emission control in internal combustion engines.
Innovation Solution
A reductant delivery system with a fluidic pump and injector upstream of the catalytic device, controlled by a pressure sensor to determine a zero-flow pressure and adjust the injector activation based on the difference between expected and actual pressure drops, using a proportional-integral control relationship to optimize reductant injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reductant injection is controlled using feedback from downstream NOx sensor monitoring, then emission control accuracy is improved, but system latency increases and dynamic responsiveness deteriorates
Solution Approach 1:
The system performs preliminary action by monitoring upstream pressure conditions before reductant injection occurs and before exhaust gases reach downstream sensors. This advance monitoring allows the control system to predict and adjust injection parameters proactively, eliminating the time delay inherent in waiting for downstream sensor feedback. The pressure differential measurement provides real-time information about injection system status without requiring downstream exhaust analysis.
Solution Approach 2:
The invention introduces an intermediary measurement approach by using upstream pressure differential as a proxy indicator for injection system performance. Instead of directly measuring downstream emissions with latency, the system uses pressure sensor readings from the upstream side of the injector as an intermediate signal that correlates with injection effectiveness. This intermediary measurement enables real-time control without the temporal delay of downstream monitoring.
2Object-generated harmful factors
If reductant injection is controlled using downstream feedback, then emission purification is improved, but dynamic responsiveness during engine operation deteriorates
Solution Approach 1:
The system implements feedback control using upstream pressure differential measurements that provide real-time information about injection system status. The control module continuously monitors the pressure difference across the injector and adjusts injection parameters based on this immediate feedback, enabling rapid dynamic response. This upstream feedback mechanism eliminates the inherent delay in downstream sensor-based control while maintaining effective emission purification through adaptive injection control.
Solution Approach 2:
The control system takes preliminary action by detecting pressure changes upstream of the injector before injection occurs and adjusting injection timing and quantity in real-time. This proactive control based on upstream pressure conditions allows the system to respond dynamically to changing engine operating conditions without waiting for downstream exhaust analysis, thereby maintaining both emission purification effectiveness and rapid dynamic responsiveness.
3Device complexity
If reductant delivery system operates without pressure-based adjustment, then system complexity is reduced, but reductant injection precision deteriorates
Solution Approach 1:
The invention replaces complex mechanical flow measurement and adjustment mechanisms with a simpler electronic pressure sensing and control system. By using pressure differential measurements across the injector and processing this data through a control module, the system achieves precise reductant injection control without requiring complex mechanical flow meters, variable geometry injectors, or other mechanically complex precision devices. This substitution maintains injection precision while reducing overall system complexity.
Solution Approach 2:
The reductant delivery system performs self-service by using its own internal pressure differential as a measurement signal for controlling injection precision. The pressure sensors monitor conditions within the existing delivery system infrastructure, and the control module uses this self-generated information to automatically adjust injection parameters. This self-service approach eliminates the need for external complex measurement and control equipment while maintaining precise injection delivery.
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 reduces system latencies and improves dynamic responsiveness, minimizing NOx reduction variation and NH3 consumption by ensuring precise reductant delivery, thereby enhancing emissions control.
Implementation Method 1
monitoring, via a pressure sensor, a pressure in the reductant delivery system upstream of the injector to determine a zero-flow pressure
Implementation Method 2
A reductant delivery system includes a fluidic pump fluidly connected to an injector
Implementation Method 3
an actual pressure drop deviation upstream of the injector is determined
Data Source
AI summary
A reductant delivery system for an internal combustion engine is arranged to inject a reductant into the exhaust aftertreatment system upstream of a catalytic device. A method for controlling the reductant delivery system includes operating the fluidic pump at a preset state, operating the injector at a zero-flow state, and monitoring, via a pressure sensor, a pressure in the reductant delivery system upstream of the injector to determine a zero-flow pressure. The injector is activated under a preset condition and an actual pressure drop upstream of the injector is monitored. A pressure drop deviation is determined based upon the actual pressure drop upstream of the injector and an expected pressure drop upstream of the injector. An adjustment to the activation of the injector is determined based upon the pressure drop deviation, and the injector is controlled based upon the adjustment.