Fuel Composition Estimation Using Pressure Change Detection
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Solution Overview
Problem
Existing methods for estimating the composition of liquefied petroleum gas (LPG) in fuel tanks are inaccurate due to factors like fuel tank refill events and residual air, leading to incorrect fuel injection and engine performance issues, including engine stalls.
Innovation Solution
A method that infers a fuel tank refill event based on the rate of change in fuel tank pressure and updates the estimated fuel composition during shutdown, ensuring accurate priming and injection settings upon engine restart, using reliable fuel tank data to improve composition estimation and engine performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel composition is estimated using fuel tank pressure and temperature, then composition estimation can be performed, but accuracy deteriorates due to refill events and residual air
Solution Approach 1:
The system performs preliminary detection of refill events by monitoring fuel tank pressure changes before composition estimation is performed. By detecting refills in advance and flagging composition estimates as unreliable, the system prevents using inaccurate data for fuel injection calculations, thereby maintaining reliability while preserving the ability to perform composition estimation.
Solution Approach 2:
The system continuously monitors fuel tank pressure and provides feedback about refill events to the composition estimation process. When pressure changes indicate a refill, the system updates the reliability status of the composition estimate, creating a feedback loop that prevents using outdated or inaccurate composition data for fuel injection control.
2Measurement precision
If fuel composition is updated continuously, then accuracy improves, but computational complexity increases
Solution Approach 1:
Instead of continuous composition updates, the system performs composition estimation periodically based on triggered events (refill detection, engine shutdowns, restarts). This periodic approach maintains accuracy by updating composition data when necessary while reducing computational complexity by avoiding constant monitoring and calculation.
Solution Approach 2:
The system changes the state parameter of composition estimation from continuous to event-triggered. By monitoring specific parameters (pressure change rate, shutdown status) and updating composition only when thresholds are met, the system achieves necessary accuracy while minimizing computational burden.
3Reliability
If fuel rail priming duration is extended, then engine startability improves, but time loss increases
Solution Approach 1:
The system dynamically adjusts fuel rail priming duration based on real-time composition data and detected refill events. When a refill is detected and composition is updated, the system calculates the optimal priming duration needed for the new composition, avoiding both excessive priming (time loss) and insufficient priming (startability issues).
Solution Approach 2:
The system performs fuel rail priming as a preliminary action before engine restart, using the most recent composition data available. By calculating and executing the necessary priming duration before startup, the system ensures reliable engine startability while minimizing the time required, as the priming is performed only when necessary based on composition changes.
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 enhances the accuracy and reliability of fuel composition estimation, reducing engine stalls and improving performance by ensuring sufficient fuel rail priming and adjusting engine operations based on updated composition data.
Implementation Method 1
a fuel pump configured to deliver the gaseous fuel from the fuel tank to the engine
Implementation Method 2
a pressure regulator configured to regulate a pressure of the gaseous fuel delivered by the fuel pump
Data Source
AI summary
Methods and systems are provided for operating a fuel system configured to deliver a gaseous fuel to an engine. Following tank refilling, the fuel composition is selectively updated based on fuel tank pressure, temperature, and air content data. When the engine is subsequently restarted, the fuel rail is primed for a duration based on the updated composition.