Engine Intake Air Control During Fuel Cut for Catalyst Cooling
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Solution Overview
Problem
Existing catalyst devices in internal combustion engines, particularly those with three-way catalysts, face issues with excessive temperature rise during fuel cuts, leading to reduced NOx purification performance due to oxygen absorption, which is not effectively addressed by existing methods.
Innovation Solution
An engine system with a control unit that adjusts intake air amount and fuel supply to manage catalyst temperature, implementing intake air amount increase during fuel cuts when the catalyst is overheating and increasing fuel supply post-cut to consume absorbed oxygen, while preventing excessive air-fuel reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the intake air amount is increased during fuel cut to cool the catalyst device, then the catalyst temperature is reduced, but the oxygen absorption in the three-way catalyst increases causing poor NOx purification performance
Solution Approach 1:
The control unit increases the intake air amount during fuel cut before the fuel supply is resumed, proactively cooling the catalyst device to prevent excessive temperature rise that would occur after fuel supply resumption. This preliminary cooling action ensures the catalyst temperature remains within the optimal range for NOx purification when fuel supply is restored.
Solution Approach 2:
The intake air amount is dynamically adjusted based on real-time catalyst temperature conditions. When the catalyst temperature exceeds a predetermined threshold during fuel cut, the control unit increases the intake air amount; when the temperature is within the acceptable range, the normal fuel cut control is maintained. This dynamic adjustment optimizes both catalyst temperature control and NOx purification performance.
2Temperature
If the intake air amount is increased during fuel cut, then the catalyst device is cooled, but the air-fuel ratio in the catalyst device becomes leaner making it difficult to reduce NOx
Solution Approach 1:
The control unit increases the intake air amount during fuel cut before the fuel supply is resumed, proactively cooling the catalyst device to prevent excessive temperature rise that would occur after fuel supply resumption. This preliminary cooling action ensures the catalyst temperature remains within the optimal range for NOx purification when fuel supply is restored.
Solution Approach 2:
The intake air amount is dynamically adjusted based on real-time catalyst temperature conditions. When the catalyst temperature exceeds a predetermined threshold during fuel cut, the control unit increases the intake air amount; when the temperature is within the acceptable range, the normal fuel cut control is maintained. This dynamic adjustment optimizes both catalyst temperature control and NOx purification performance.
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
Effectively prevents catalyst overheating and enhances NOx purification performance by controlling intake air and fuel supply, ensuring reliable catalyst operation and improved emissions control.
Implementation Method 1
If the catalyst device includes a three-way catalyst, oxygen is absorbed in the three-way catalyst in the fuel cut.
Implementation Method 2
the amount of air drawn into the combustion chamber is increased and a large amount of air is introduced into the exhaust passage, therefore into the catalyst device, to cool the catalyst device with the air
Data Source
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AI summary
When an accelerator opening degree is lower than a predetermined accelerator determination opening degree, a control device implements a fuel cut that stops fuel supply; when the control device implements the fuel cut, the control device implements an intake air amount increase control so that an intake air amount is larger when a catalyst temperature is high than when the catalyst temperature is low; when the control device ends the fuel cut and resumes fuel supply, the control device implements a fuel amount increase so that a fuel amount to be supplied to a combustion chamber is larger than a basic fuel amount; and the control device prohibits the intake air amount increase control for a predetermined period after the control device ends the fuel amount increase control.