Transient Control for Dedicated EGR Engines
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Solution Overview
Problem
Dedicated EGR engines face challenges in controlling combustion parameters due to variations in fuel quality, sensor errors, and estimation errors of air-fuel ratio, EGR, and fueling during transient events, leading to unmet needs for effective control strategies.
Innovation Solution
An electronic control system is implemented to determine and control combustion parameters for dedicated EGR engines, including independent fueling of dedicated and non-dedicated cylinders, responsive to inert matter, unburned air, and unburned fuel, accounting for transport delays and mixing effects within the EGR loop, using feedback and feedforward controllers to optimize combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated EGR cylinders are used to provide EGR via an EGR flow loop, then EGR quality is increased, but control problems are compounded during transient events
Solution Approach 1:
The engine control is segmented into multiple independent controllers: a first controller for non-dedicated cylinders and a second controller for dedicated EGR cylinders. This segmentation allows each controller to independently manage its respective cylinders, simplifying the control of transient events while maintaining high EGR quality through the dedicated EGR system.
Solution Approach 2:
The electronic control system determines combustion control parameters in advance for both non-dedicated and dedicated EGR cylinders. By calculating and preparing the appropriate fueling and air handling parameters before transient events occur, the system can quickly respond to changes without compromising EGR quality or control stability.
2Manufacturing precision
If independent fueling of dedicated and non-dedicated cylinders is implemented, then combustion control is improved, but device complexity increases
Solution Approach 1:
The control system is divided into separate functional blocks: a first controller managing non-dedicated cylinders and a second controller managing dedicated EGR cylinders. Each controller independently determines combustion control parameters for its assigned cylinders, achieving precise combustion control while keeping each control module relatively simple and modular.
3Measurement precision
If feedback and feedforward controllers are used to compensate for variations, then combustion parameter accuracy is improved, but computational requirements increase
Solution Approach 1:
The feedforward controller pre-calculates compensation parameters based on expected variations in fuel quality, sensor errors, and transient conditions. By determining correction factors in advance rather than reacting to deviations, the system achieves high combustion parameter accuracy with reduced real-time computational burden on the electronic control system.
Solution Approach 2:
The feedback controller continuously monitors actual combustion parameters and adjusts control signals to correct deviations from target values. This closed-loop feedback mechanism compensates for unmodeled variations and disturbances, improving measurement precision while using simple proportional-integral-derivative control algorithms that are computationally efficient.
Data Source
AI summary
One embodiment is a system comprising an engine including a dedicated EGR cylinder configured to provide EGR to the engine via an EGR loop, a non-dedicated cylinder, a plurality of injectors, an ignition system including a plurality of spark plugs, an intake throttle, and an electronic control system. The electronic control system is configured to control combustion during transient operation of the engine by determining one or more combustion control parameters compensating for variation of one or more of inert matter, unburned air and unburned fuel in EGR output by the dedicated EGR cylinder during transient operation of the engine, and an effect of the EGR loop on inert matter, unburned air and unburned fuel provided to the plurality of cylinders, and controlling operation of at least one of the throttle, the ignition system and the plurality of injectors in response to at least one of the one or more combustion control parameters.