Fuel Injection Timing Diagnosis via Crankshaft Torque Measurement

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Solution Overview

Problem

Existing methods for diagnosing faults in fuel injection systems of internal combustion engines, particularly Diesel engines, are inadequate as they rely on assumptions about the relationship between energizing time corrections and injection timing, which is not immediately related to combustion quality, leading to potential excessive emission levels.

Innovation Solution

A method that involves commanding a test fuel injection pulse, measuring the torque released to the crankshaft, calculating the difference between actual and expected torque, and diagnosing faults if the difference exceeds a threshold, using an empirically determined map correlating torque with engine operating parameters, and performing an emergency procedure if necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If energizing time corrections are monitored to detect injection timing faults, then the OBD system can identify potential fuel injection malfunctions, but the detection accuracy is insufficient because there is no immediate and necessary relationship between energizing time and injection timing

Engineering Contradiction:

Improvefault detection reliabilityVSAvoidinjection timing measurement precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the indirect electrical monitoring method (energizing time measurement) with a direct mechanical measurement method (crankshaft position sensing). By using a crankshaft position sensor to directly measure the actual injection timing relative to the crankshaft position, the system eliminates the assumption-based indirect measurement and achieves accurate direct measurement of injection timing, thereby resolving the contradiction between detection reliability and measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the OBD system uses energizing time corrections exceeding a calibrated threshold to detect malfunctions, then it can provide a simple detection method, but it may generate false positives or miss actual timing drifts that do not affect energizing time

Engineering Contradiction:

Improvedetection method simplicityVSAvoidinjection timing fault detection reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the complex indirect detection method based on energizing time corrections with a simple direct measurement method using crankshaft position sensing. The crankshaft position sensor directly measures the actual injection timing, providing both simplicity in implementation and high reliability in detecting timing drifts, regardless of whether they affect energizing time or not.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback mechanism where the actual injection timing measured by the crankshaft position sensor is continuously compared with the expected injection timing. This feedback loop allows the OBD system to accurately detect any deviations in injection timing and generate appropriate diagnostic alerts, improving reliability while maintaining operational simplicity.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If the ECU implements compensation strategy to correct energizing time, then it can maintain desired fuel quantity, but injection timing may still drift due to mechanical damages, ECU computing errors, or production spread

Engineering Contradiction:

Improvefuel quantity control precisionVSAvoidinjection timing accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent introduces a mechanical measurement system (crankshaft position sensor) that independently verifies the actual injection timing, separate from the ECU's electrical control and compensation mechanisms. This mechanical measurement provides an objective reference that can detect timing drifts caused by mechanical wear, manufacturing variations, or computational errors, thereby ensuring timing accuracy even when the compensation strategy is actively correcting fuel quantity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides a more reliable detection of injection timing faults, ensuring proper fuel delivery and reducing emissions by directly correlating torque with combustion quality, thus improving the accuracy of fault diagnosis without affecting normal engine operation.

Implementation Method 1

commanding an injection pulse for injecting a test quantity of fuel into an engine cylinder

Methodology Applied

Scientific EffectFuel injection: Injector

Implementation Method 2

determining the torque released to an engine crankshaft due to a combustion of said injected fuel quantity

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS8751135B2Method to diagnose a fault in a fuel injection system of an internal combustion engine

Publication Date: 2014.06.10 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method is provided to diagnose a fault in a fuel injection system of an internal combustion engine. The method includes, but is not limited to commanding an injection pulse for injecting a test quantity of fuel into an engine cylinder, determining the torque released to an engine crankshaft due to the injection pulse, calculating the difference between this released torque and an expected value for the torque, and of detecting a fault in the fuel injection system if the difference exceeds a threshold.