Fuel Injector Deviation Learning via Minimum Injection Interval

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Solution Overview

Problem

Existing fuel injection control systems struggle to accurately learn and compensate for variations in fuel injection characteristics of fuel injectors, particularly under high-speed and high-load conditions, leading to potential deterioration in engine output characteristics and drivability.

Innovation Solution

A system that detects the minimum interval between fuel injection periods and learns the deviation from a reference injection characteristic by adjusting the displacement of the fuel injector's actuator, ensuring non-overlapping injection periods and correcting for variations in the full lift stroke of the needle valve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fuel injection control systems use learned values to compensate for variations in fuel injection characteristics, then fuel injection accuracy is improved, but the system cannot accurately learn deviations under high-speed and high-load conditions

Engineering Contradiction:
Improvefuel injection accuracyVSAvoidadaptability to high-speed and high-load conditions
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the learning method adaptive to different operating conditions. The system dynamically selects between two learning methods: using crankshaft acceleration for low-speed/low-load conditions and using minimum interval between injection periods for high-speed/high-load conditions. This dynamic adaptation resolves the contradiction by ensuring accurate learning across the full operating range of the engine.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter used for learning based on operating conditions. At low speeds, it uses crankshaft acceleration parameters; at high speeds, it switches to minimum interval between injection periods. This parameter change allows the system to maintain measurement precision across varying operating conditions, particularly enabling accurate learning under high-speed and high-load conditions where the previous method failed.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the system uses crankshaft acceleration to learn fuel injection deviations, then learning is accurate under low-speed conditions, but the method becomes ineffective under high-speed and high-load conditions

Engineering Contradiction:
Improvelearning accuracy under low-speed conditionsVSAvoidengine speed range applicability
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The system dynamically switches between two learning methods based on engine operating conditions. At low speeds, it uses crankshaft acceleration measurement which provides accurate learning. At high speeds, it transitions to using the minimum interval between injection periods method. This dynamic switching resolves the contradiction by maintaining learning accuracy across the entire engine speed range.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent segments the learning process into two distinct methods applicable to different operating conditions. The first method (crankshaft acceleration) handles low-speed conditions, while the second method (minimum interval measurement) handles high-speed conditions. This segmentation allows each method to be optimized for its specific operating range, resolving the speed range applicability issue.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If fuel injectors have individual variations in injection characteristics, then manufacturing simplicity is maintained, but fuel injection uniformity across cylinders deteriorates

Engineering Contradiction:
Improvefuel injector manufacturing simplicityVSAvoidfuel injection uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements feedback by measuring the actual fuel injection characteristics through crankshaft acceleration or minimum interval measurements, comparing them against target values, and using the deviations to correct fuel injection quantities. This feedback loop compensates for individual variations in fuel injector characteristics, achieving uniform fuel injection across all cylinders while maintaining manufacturing simplicity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-correction by automatically learning and compensating for individual fuel injector variations without requiring manual calibration or precision manufacturing. Each fuel injector system learns its own characteristics and adjusts its operation accordingly, achieving uniformity through self-service rather than through complex manufacturing processes.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS7522987B2Fuel injection control system
Publication Date: 2009.04.21 DENSO CORP
  • US7522987B2 patent drawing
  • US7522987B2 patent drawing
  • US7522987B2 patent drawing

AI summary

An apparatus aims at learning a deviation from a reference injection characteristic of a fuel injector provided for a cylinder of an engine having an output shaft. In the apparatus, a detecting unit is configured to detect a minimum interval between temporally adjacent fuel injection periods in the plurality of fuel injection periods based on a behavior of the output shaft during execution of the plurality of fuel injections. The minimum interval maintains the temporally adjacent fuel injection periods to be non-overlapped with each other. A learning unit is configured to learn the deviation from the reference injection characteristic of the fuel injector based on the detected minimum interval.