Combustion Engine Fuel Setting Control for Idle Acceleration

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Solution Overview

Problem

Existing fuel control methods for combustion engines, particularly during idle mode, result in reduced acceleration performance due to periodically extending the closing time of the fuel valve, which complicates ignition controller design and limits control bandwidth.

Innovation Solution

A control unit and method that determine a desired fuel setting by monitoring ignition timing and revolution speed variance, using convex function relationships to optimize fuel settings without relying solely on extended fuel valve closing times, allowing for efficient ignition timing control and improved acceleration performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the closing time of the fuel valve is periodically extended to make the fuel mixture leaner, then the fuel setting is optimized for emissions and combustion efficiency, but the acceleration performance is reduced during the extended closing time interval

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidacceleration performance
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent applies periodic action by using regular perturbations of the fuel valve closing time to probe the system response and determine the desired fuel setting. Instead of continuously extending the closing time, the system uses periodic, small adjustments to measure engine response (RPM changes) and iteratively converges to the optimal fuel setting, thereby avoiding prolonged periods of reduced acceleration performance while still achieving combustion optimization.

Inventive Principle:
Principle #19Periodic action

2Object-generated harmful factors

If the closing time of the fuel valve is extended to optimize fuel setting, then emissions are reduced and combustion is improved, but the ignition controller design becomes more complex and control bandwidth is limited

Engineering Contradiction:
ImproveemissionsVSAvoidignition controller design
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent implements feedback by monitoring the engine's response (RPM changes) to fuel valve closing time perturbations and using this information to update the fuel setting. The control unit continuously adjusts the fuel valve closing time based on the measured engine response, creating a closed-loop system that automatically converges to the optimal fuel setting without requiring complex pre-programmed control strategies or limiting the control bandwidth.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3814621B1Method and control unit in a combustion engine for determining a desired fuel setting
Publication Date: 2026.02.18 HUSQVARNA AB
  • EP3814621B1 patent drawingFigure 1~2
  • EP3814621B1 patent drawingFigure 3~4
  • EP3814621B1 patent drawingFigure 5~6

AI summary

A method in a combustion engine 100 for determining a desired fuel setting λ+. The method comprises configuring a fuel setting λ, determining a combustion engine parameter β in dependence of the configured fuel setting λ, wherein the combustion engine parameter is related to the fuel setting by a convex function relationship, and updating the fuel setting λ towards the desired fuel setting λ+, based on the determined combustion engine parameter β and on the convex function relationship between the fuel setting λ and the combustion engine parameter β.