Fuel Control Apparatus for Stabilizing Engine Idling During Consecutive Startups
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Solution Overview
Problem
Existing fuel control systems for internal combustion engines using heavy fuel struggle with unstable idling due to combustion state deterioration, particularly during consecutive startups, as they fail to accurately judge the miss firing state and adjust fuel amounts accordingly, leading to inadequate heavy fuel corresponding control.
Innovation Solution
A fuel control apparatus that includes miss firing judging, fuel property judging, heavy fuel correspondence controlling, and running time period calculating means to determine when alternative control is necessary, increasing the fuel amount during re-startups if the running time period is short, thereby stabilizing combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If catalyst warm-up control is carried out by retarding ignition timing and leaning the air-fuel ratio, then catalyst activation is accelerated, but combustion state deteriorates causing unstable idling
Solution Approach 1:
The system performs preliminary judgment of fuel properties (heavy fuel detection) before executing catalyst warm-up control. By detecting heavy fuel characteristics in advance through miss firing judgment during initial operation, the system prepares alternative control strategies to prevent combustion deterioration before it occurs during catalyst warm-up phase.
Solution Approach 2:
The system continuously monitors engine operation parameters including miss firing detection and revolution stability. Based on feedback from these measurements, the ECU dynamically adjusts fuel injection amount and determines whether to switch between catalyst warm-up control and alternative control, ensuring stable idling while achieving catalyst activation.
2Reliability
If fuel amount is increased by setting increased correction coefficient whenever miss firing is judged, then heavy fuel leaning is suppressed stabilizing idling, but fuel consumption increases
Solution Approach 1:
Instead of continuously increasing fuel amount, the system applies partial correction only when necessary. The ECU judges fuel properties and determines the degree of fuel amount correction based on detected heavy fuel characteristics and current engine operation state, applying minimal necessary correction to maintain stable idling rather than excessive fuel addition.
Solution Approach 2:
The system dynamically changes fuel injection parameters including correction coefficient based on detected fuel properties and engine operating conditions. The ECU adjusts the correction coefficient magnitude according to the severity of heavy fuel characteristics and current combustion state, optimizing the balance between idling stability and fuel consumption.
3Adaptability or versatility
If consecutive re-startup is judged based on temperature difference between cooling water and intake air, then re-startup detection is performed, but precise judgment of evaporated fuel supply condition is not achieved
Solution Approach 1:
The system uses engine revolution fluctuation as an intermediary indicator to indirectly detect miss firing caused by evaporated fuel. Instead of directly measuring evaporated fuel amount, the ECU monitors revolution stability and miss firing patterns, which serve as intermediate signals reflecting the underlying fuel vaporization condition during re-startup.
Solution Approach 2:
The system replaces direct thermal measurement with mechanical revolution monitoring to detect fuel vaporization effects. By substituting temperature-based detection with engine performance monitoring (revolution stability), the system achieves more precise indirect measurement of evaporated fuel supply conditions that directly affect combustion.
4Reliability
If alternative control is performed by increasing fuel amount during re-startup with short running time period, then combustion state deterioration is suppressed, but fuel injection control complexity increases
Solution Approach 1:
The control system segments the operating conditions into distinct phases: initial operation phase for fuel property judgment, catalyst warm-up phase, and re-startup phase with short running time period. Each phase has predetermined control strategies stored in memory, allowing the ECU to select appropriate control mode without complex real-time calculations, thus managing complexity while maintaining combustion stability.
Data Source
AI summary
When a combustion feedback correction coefficient to which a predetermined value is added in correspondence to half miss firing judgment exceeds a heavy fuel judgment value (K0), heavy fuel judgment is made, and heavy fuel corresponding control for increasing the fuel amount by a combustion feedback correction coefficient (Kfb) and by prolongation of increasing fuel amount (τ) immediately after the startup is performed. When startup is consecutive startup, having a small drop width of a cooling water temperature (TH), from the last engine stop, and the number of times of ignition (Nig) accumulated during the last running is smaller than a warming judgment value (Nig0) at re-startup after running under the heavy fuel corresponding control, miss firing judgment is regarded as being impossible and alternative control for increasing the fuel amount is performed instead of the heavy fuel corresponding control.