Engine Intake Air Cooling Control for Lean-Stoichiometric Switching
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Solution Overview
Problem
Existing engine technologies face challenges in reducing NOx emissions when switching between lean and stoichiometric combustion modes due to intermediate air-fuel ratios, which hinder NOx removal by catalysts and are influenced by in-cylinder temperature.
Innovation Solution
A control device for an engine that includes an intake air cooler and a controller to manage the switching between combustion modes by starting intake air cooling before adjusting the air-fuel ratio, ensuring the cooling is completed before finishing the air-fuel ratio adjustment, and optimizing the cooling period to minimize NOx generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intake air cooling is performed when switching from stoichiometric mode to lean mode, then control accuracy of air-fuel ratio is improved, but NOx emissions increase during mode transition due to intermediate air-fuel ratio
Solution Approach 1:
The patent applies preliminary action by starting intake air cooling before the air-fuel ratio switching is completed. The cooling is initiated when a request for mode switching is detected, and the cooling continues until after the air-fuel ratio has fully transitioned to the lean mode. This ensures that the intake air temperature is reduced during the transition period, preventing excessive NOx generation while maintaining the cooling benefit for improved air-fuel ratio control accuracy.
2Object-generated harmful factors
If intake air cooling is started before air-fuel ratio switching, then NOx generation is suppressed, but switching time is extended
Solution Approach 1:
The patent implements periodic action by controlling the intake air cooling in a time-dependent manner during mode transition. The cooling is activated at a specific timing (when switching request is detected) and deactivated at another specific timing (after air-fuel ratio switching is finished). This periodic control ensures that cooling is applied only during the necessary transition period, suppressing NOx generation while minimizing the extension of switching time.
3Object-generated harmful factors
If intake air cooling is continued after air-fuel ratio switching finishes, then NOx emissions are reduced, but energy consumption increases
Solution Approach 1:
The patent applies feedback control by monitoring the air-fuel ratio switching status and using this information to control the intake air cooling. The cooling is started when a request for switching is detected and is ended after the air-fuel ratio switching has finished. This feedback-based control ensures that cooling is maintained during the transition period to reduce NOx emissions, but is terminated promptly after switching completes, avoiding unnecessary energy consumption.
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 effectively reduces NOx emissions by lowering in-cylinder temperature during mode transitions and ensures efficient air-fuel ratio adjustments, outperforming conventional techniques by utilizing cooling effects without waste and shortening switching times.
Implementation Method 1
an intake air cooler that cools intake air supplied to the combustion chamber
Data Source
AI summary
A control device for an engine is provided, which includes a combustion chamber formed by a cylinder and a piston, an intake air amount adjuster that adjusts an intake air amount supplied to the combustion chamber, a controller switchable of a combustion mode between a fuel-lean first combustion mode and a stoichiometric second combustion mode based on an engine operating state, and an intake air cooler that cools the intake air supplied to the combustion chamber. The controller controls the intake air cooler to start intake air cooling in response to a request for switching the combustion modes, and after the intake air cooling is started, controls the intake air amount adjuster to start the switching of the combustion modes, and then controls the intake air cooler and the intake air amount adjuster so that the switching of the combustion modes ends after the intake air cooling is finished.