Engine Controller Dither Purge Control Air-Fuel Ratio Deviation
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Solution Overview
Problem
Existing controllers for internal combustion engines face challenges in maintaining a consistent air-fuel ratio across cylinders during dither control and purge control, leading to combustion deterioration due to uneven fuel vapor distribution.
Innovation Solution
A controller that executes dither control by differentiating air-fuel ratios between cylinders and limits the purge flow rate during dither control to reduce deviations from the target air-fuel ratio, using a guard process to set a target purge parameter and adjust the purge flow rate, and optionally prohibits purge control or stops the dither control when the deviation becomes excessive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dither control is executed to increase catalyst temperature, then catalyst temperature increases, but air-fuel ratio distribution becomes uneven and combustion deteriorates
Solution Approach 1:
The patent applies local quality by differentiating air-fuel ratios between specific cylinders (rich and lean cylinders) rather than treating all cylinders uniformly. This localized differentiation enables the catalyst temperature increase while controlling the overall combustion quality through strategic air-fuel ratio distribution.
Solution Approach 2:
The patent changes the air-fuel ratio parameter differently for different cylinders during dither control. By making at least one cylinder rich and at least one cylinder lean, the system achieves catalyst temperature increase while managing combustion stability through parameter variation.
2Quantity of substance
If purge control is executed to return fuel vapor to intake passage, then fuel vapor is recycled, but fuel vapor distribution becomes uneven and air-fuel ratio deviates from target
Solution Approach 1:
The patent performs preliminary action by determining whether dither control is being executed before executing purge control. This preliminary check allows the system to prevent purge control during dither control, avoiding uneven fuel vapor distribution and air-fuel ratio deviation.
Solution Approach 2:
The patent applies preliminary anti-action by preventing purge control when dither control is active. This preemptive prevention avoids the harmful effect of uneven fuel vapor distribution that would occur if purge control were executed during dither control.
3Quantity of substance
If purge control is executed during dither control, then fuel vapor is recycled, but combustion deterioration tendency is promoted due to uneven fuel vapor distribution
Solution Approach 1:
The patent performs preliminary action by checking whether dither control is being executed before allowing purge control. This preliminary determination prevents the combination of purge control and dither control that would cause combustion deterioration.
Solution Approach 2:
The patent applies preliminary anti-action by preventing purge control during dither control execution. This preemptive measure avoids promoting combustion deterioration through uneven fuel vapor distribution.
Data Source
AI summary
A controller for an internal combustion engine is configured to execute a dither control process, a purge control process, and a limiting process. The dither control process operates the fuel injection valves such that at least one of the cylinders is a lean combustion cylinder, in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and at least another one of the cylinders is a rich combustion cylinder, in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio. The purge control process controls the purge flow rate by operating the adjustment device. The limiting process limits the purge control process such that, when the dither control process is being executed, the purge flow rate is reduced as compared to a case in which the dither control process is not being executed.