Engine SCR Control via Dynamic Weighting Factors
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Solution Overview
Problem
Existing control systems for internal combustion engine systems with SCR exhaust aftertreatment struggle to tailor controls to varying engine and SCR operating conditions, and accommodate differences in platform and hardware, leading to inefficiencies and burdens on the SCR catalyst.
Innovation Solution
The implementation of unique control methods and systems that regulate engine out NOx emissions and aftertreatment temperature conditions through EGR cooler bypass operation, utilizing an electronic control unit (ECU) to manage combustion parameters and EGR fraction, and employing lookup tables and weighting factors to adjust control modes based on engine operating conditions and SCR efficiency levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing control systems are used for internal combustion engine systems with SCR exhaust aftertreatment, then the system structure is simple, but the ability to tailor controls to different engine and SCR operating conditions is insufficient
Solution Approach 1:
The control system dynamically adjusts control parameters based on real-time engine operating conditions and SCR efficiency levels. The ECU continuously monitors parameters such as engine speed, load, temperature, and SCR conversion efficiency, then adapts control strategies including EGR fraction, injection timing, and reductant dosing rates to optimize performance across varying operating conditions.
Solution Approach 2:
The system changes control parameters such as EGR fraction, fuel injection timing, and reductant dosing based on detected operating conditions. When SCR efficiency drops below thresholds, the system adjusts these parameters to reduce the burden on the SCR catalyst or maintain optimal operating temperatures, thereby adapting control behavior to different operational states.
2Adaptability or versatility
If existing control systems are used, then hardware requirements are minimal, but the ability to accommodate variations in platform and hardware is limited
Solution Approach 1:
The control system is designed with universal adaptability to accommodate different engine platforms and hardware configurations. The ECU uses configurable parameters and lookup tables that can be tailored to specific engine types, SCR catalyst characteristics, and hardware variations, allowing a single control architecture to serve multiple applications while optimizing performance for each specific configuration.
3Reliability
If engine out NOx is not regulated, then engine performance is maintained, but the burden on the SCR catalyst increases
Solution Approach 1:
The system implements feedback control by monitoring SCR conversion efficiency, aftertreatment temperature, and engine operating conditions. Based on this feedback, the ECU adjusts engine out NOx levels through EGR fraction control and fuel injection adjustments, ensuring that the SCR catalyst operates within optimal parameters while maintaining acceptable engine performance. The feedback loop continuously balances NOx reduction needs against engine performance requirements.
4Reliability
If aftertreatment temperature is not controlled, then system complexity is reduced, but SCR catalyst efficiency is compromised
Solution Approach 1:
The control system performs preliminary thermal management by predicting required aftertreatment temperatures based on engine operating conditions and proactively adjusting EGR fraction and fuel injection timing to achieve target temperatures before SCR operation becomes critical. This preventive approach ensures optimal SCR efficiency is maintained without requiring complex real-time temperature control mechanisms.
Data Source
AI summary
An electronic control system is adapted to control a system including an internal combustion engine and an exhaust aftertreatment system including an SCR catalyst. The electronic control system provides a first dynamically determined weighting factor in response to performing a selected one of a plurality of calculations, determines an operating mode of the engine in response to an engine load and an engine speed, selects one of a plurality of inputs in response to the operating mode of the engine to provide an interpolation weighting factor, the plurality of inputs including the first dynamically determined weighting factor and one or more predetermined weighting factors, utilizes the interpolation weighting factor to interpolate between a first set of combustion control data and a second set of combustion control data to determine a set of combustion control values, and controls operation of the engine using the set of combustion control values.