Method and systems for airflow control
First Claim
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1. A system for an engine having an intake manifold and a plurality of cylinders, comprising:
- a controller storing instructions executable to adjust an exhaust gas recirculation (EGR) amount supplied to the engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range by;
obtaining a base intake manifold oxygen concentration from a first map based on engine speed and/or engine load;
adjusting the base intake manifold oxygen concentration based on a brake-specific NOx value to obtain a target intake manifold oxygen concentration, the brake-specific NOx value determined from a NOx sensor feedback signal, engine speed, engine load, ambient humidity, an exhaust oxygen concentration, and a fuel quantity command;
converting the target intake manifold oxygen concentration to a target intake gas fraction; and
adjusting a position of an EGR valve based on the target intake gas fraction and a feedback value, the feedback value determined based on a measured EGR valve position and corrected in accordance with an intake manifold air flow rate.
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Abstract
Various methods and systems are provided for controlling emissions. In one example, a controller is configured to respond to a sensed or estimated intake oxygen fraction by controlling an exhaust gas recirculation (EGR) amount supplied to an engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range, and adjusting a target intake manifold oxygen fraction or target intake manifold EGR fraction in response to a NOx sensor feedback signal.
70 Citations
13 Claims
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1. A system for an engine having an intake manifold and a plurality of cylinders, comprising:
a controller storing instructions executable to adjust an exhaust gas recirculation (EGR) amount supplied to the engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range by; obtaining a base intake manifold oxygen concentration from a first map based on engine speed and/or engine load; adjusting the base intake manifold oxygen concentration based on a brake-specific NOx value to obtain a target intake manifold oxygen concentration, the brake-specific NOx value determined from a NOx sensor feedback signal, engine speed, engine load, ambient humidity, an exhaust oxygen concentration, and a fuel quantity command; converting the target intake manifold oxygen concentration to a target intake gas fraction; and adjusting a position of an EGR valve based on the target intake gas fraction and a feedback value, the feedback value determined based on a measured EGR valve position and corrected in accordance with an intake manifold air flow rate. - View Dependent Claims (2, 3, 4)
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5. A method for an engine having an intake manifold and a plurality of cylinders, comprising:
with instructions executable by a controller, controlling an exhaust gas recirculation (EGR) amount supplied to the engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range by; adjusting a target intake manifold oxygen concentration based on a NOx sensor feedback signal; converting the target intake manifold oxygen concentration to a target fresh air fraction; and adjusting the position of an EGR valve based on the target fresh air fraction and a fresh air fraction feedback value, the fresh air fraction feedback value determined based on a measured EGR valve position, an intake volumetric efficiency model, and an air-fuel ratio-based fresh air fraction estimation. - View Dependent Claims (6, 7, 8, 9)
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10. A system, comprising:
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an engine having an intake manifold and a plurality of cylinders; an exhaust gas recirculation (EGR) passage configured to recirculate exhaust gas from at least a subset of the plurality of cylinders to the intake manifold; and a controller storing instructions executable to control an EGR amount supplied to the engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range by; adjusting a target intake manifold oxygen concentration based on a NOx sensor feedback signal; converting the target intake manifold oxygen concentration to a target EGR fraction; and adjusting a position of an EGR valve based on the target EGR fraction and an EGR fraction feedback value, the EGR fraction feedback value determined based on a measured EGR valve position, an intake manifold volumetric efficiency model, and an air-fuel ratio-based EGR fraction estimation. - View Dependent Claims (11, 12, 13)
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Specification