Engine Purge Control Stabilizing Air-Fuel Ratio
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Solution Overview
Problem
The air-fuel ratio in an engine device tends to be unstable during the second purge due to the longer path for evaporated fuel gas to reach the combustion chamber and fluctuations in supercharging pressure, leading to low accuracy in the purge concentration-related value.
Innovation Solution
The engine device includes a controller that corrects the purge concentration-related value by setting it closer to the value immediately before switching from the second purge to the first purge, using a reflection factor based on the difference between stored values and considering intake air temperature and high-temperature non-execution counter values, to maintain a more appropriate air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the second purge passage is used to supply evaporated fuel gas to the intake pipe upstream of the compressor, then the purge efficiency is improved, but the air-fuel ratio stability deteriorates due to longer travel time and supercharging pressure fluctuations
Solution Approach 1:
The patent divides the single purge passage into two separate purge passages: a first purge passage that supplies evaporated fuel gas downstream of the throttle valve (shorter path), and a second purge passage that supplies evaporated fuel gas upstream of the compressor (longer path with higher efficiency). The system can selectively switch between these two passages based on operating conditions, allowing it to optimize between purge efficiency and air-fuel ratio stability as needed.
2Extent of automation
If the purge concentration-related value is learned during the second purge, then the purge control is optimized, but the accuracy of the learned value deteriorates due to air-fuel ratio instability
Solution Approach 1:
The patent performs preliminary learning of the purge concentration-related value during the first purge when air-fuel ratio stability is high and the learning conditions are favorable. This pre-learning establishes a baseline value that can be used as a reference when switching to the second purge, where learning is avoided or limited due to instability. This ensures accurate purge control without the need to learn during unstable conditions.
3Adaptability or versatility
If switching between first and second purge passages is implemented, then the system adaptability is improved, but the device complexity increases due to additional control logic
Solution Approach 1:
The patent implements a dynamic switching mechanism that automatically selects between the first and second purge passages based on real-time engine operating conditions such as load, speed, and temperature. The control system monitors these parameters and transitions between passages as needed, providing adaptability without requiring manual intervention or overly complex control logic. The switching criteria are based on predefined thresholds that simplify the control decision-making process.
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 correction method promptly stabilizes the air-fuel ratio by adjusting the purge concentration-related value, reducing fluctuations and improving accuracy, especially during transitions between purge passages.
Implementation Method 1
a second purge passage through which the evaporated fuel gas is supplied for purging to the intake pipe, upstream of a compressor of a turbocharger, by an ejector that generates a negative pressure using a supercharging pressure from the turbocharger
Data Source
AI summary
When first switching of switching from a first purge of supplying evaporated fuel gas to an intake pipe through a first purge passage to a second purge of supplying the evaporated fuel gas to the intake pipe through a second purge passage occurs and then second switching of switching from the second purge to the first purge occurs, a purge concentration-related value is corrected to a value closer to a first stored value that is the purge concentration-related value immediately before the first switching than to a second stored value that is the purge concentration-related value immediately before the second switching.