LNG Engine Control Feedback for Methane-Aware Failure Diagnosis
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Solution Overview
Problem
In LNG vehicles, the variation in fuel composition due to differing boiling points causes methane to vaporize first, leading to heavier fuel supply, which affects the accuracy of defect diagnosis in the fuel supply system, making normal diagnosis impossible.
Innovation Solution
An engine control device that calculates a feedback correction value based on the actual and target fuel supply amounts, modifies it with methane values, and performs defect diagnosis using a modified feedback correction value to ensure accurate system diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is performed based on the deviation between actual and target fuel supplying amounts, then the fuel supply system is controlled to maintain target supply levels, but the defect diagnosis accuracy deteriorates because the feedback correction value varies due to fuel composition changes
Solution Approach 1:
The patent introduces a methane value parameter to characterize fuel composition changes. By acquiring the methane value and using it to modify the feedback correction value, the system adapts to varying fuel composition while maintaining both control reliability and diagnosis accuracy. This parameter change approach allows the system to compensate for the variability caused by different fuel grades and storage conditions.
Solution Approach 2:
The methane value acts as an intermediary parameter between the fuel supply system and the control/diagnosis system. By acquiring this intermediate characteristic of the fuel and using it to modify the feedback correction value, the system can accurately diagnose defects without being misled by normal variations in fuel composition. The intermediary allows separation of control functions from diagnosis functions.
2Device complexity
If methane vaporization is allowed to occur naturally, then the fuel supply system remains simple, but the fuel composition changes causing heavier fuel supply and diagnostic errors
Solution Approach 1:
The patent implements a feedback mechanism where the methane value (representing fuel composition) is continuously acquired and used to modify the feedback correction value. This feedback loop allows the system to compensate for methane vaporization effects in real-time, maintaining diagnostic accuracy without requiring complex physical modifications to the fuel supply system. The feedback approach adapts to natural vaporization processes rather than attempting to prevent them.
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
Enables normal performance of defect diagnosis in the fuel supply system by accounting for methane vaporization, thereby maintaining diagnostic accuracy.
Implementation Method 1
methane with a low boiling point is vaporized first and emitted to the atmosphere because the components of the fuel have different boiling points
Data Source
AI summary
This control device for an engine provided with a fuel supply system capable of supplying liquefied natural gas to the engine as fuel comprises: a control unit for calculating a feedback adjustment value on the basis of a deviation between an actual fuel supply quantity and a target fuel supply quantity, and performing feedback control of the fuel supply system on the basis of the calculated feedback adjustment value; an acquiring unit for acquiring a methane number of the liquefied natural gas; a correcting unit for correcting the feedback adjustment value on the basis of the acquired methane number; and a failure diagnosis unit for performing failure diagnosis of the fuel supply system on the basis of the corrected feedback adjustment value. The engine control device can allow the failure diagnosis of the fuel supply system to operate normally.