Engine Fuel Injection Control for Air-Fuel Ratio Stability
Solution Overview
Problem
Engine devices experience fluctuations in air-fuel ratios due to inconsistent purge conditions across different intake air amount and load ratio regions, leading to inefficiencies and potential engine instability.
Innovation Solution
The engine device employs a controller that adjusts fuel injection and purge control based on specific regions defined by intake air amount and load ratio, using more stringent purge conditions in supercharging regions to stabilize the air-fuel ratio, including temperature and fuel pressure adjustments, and determines the dominant purge type to optimize evaporated fuel gas distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the same purge conditions are applied across all intake air amount and load ratio regions, then the control system remains simple and uniform, but air-fuel ratio fluctuations occur in high load ratio regions
Solution Approach 1:
The patent divides the engine operating range into multiple regions based on intake air amount and load ratio, and applies different purge control conditions to each region. Specifically, in high load ratio regions (Rk[n-1] to Rk[n]), purge is inhibited when the air-fuel ratio correction amount has not been set in the current trip, whereas in other regions purge can proceed with standard conditions. This localized differentiation stabilizes air-fuel ratio in critical high-load regions while maintaining acceptable control complexity.
2Loss of substance
If purge is executed in all regions without restriction, then evaporated fuel is effectively managed, but air-fuel ratio fluctuations increase in high load ratio regions
Solution Approach 1:
The patent changes the purge control parameters (opening degree and timing of purge control valve) based on operating region and air-fuel ratio correction status. In high load ratio regions where the air-fuel ratio correction amount has not been set in the current trip, the purge control valve opening degree is reduced or purge is temporarily inhibited. This dynamic parameter adjustment prevents air-fuel ratio fluctuations while still managing evaporated fuel through controlled purge in other regions.
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 reduces air-fuel ratio fluctuations, enhances engine stability, and minimizes deposit formation on cylinder injection valves by applying tailored control strategies based on region-specific conditions.
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
Fuel injection control of an engine is executed by setting a required injection amount and an air-fuel ratio correction amount. When setting conditions are met, the air-fuel ratio correction amount is set for a corresponding region to which a current intake air amount or load ratio belongs among a plurality of regions into which the range of the intake air amount or the load ratio is divided such that a region of a larger intake air amount or a higher load ratio becomes wider than a region of a smaller intake air amount or a lower load ratio. When purge conditions are met, a purge control valve is controlled such that purge of supplying an evaporated fuel gas to an intake pipe is executed based on a required purge ratio.