Fuel Tank Leak Detection for Sump-Shaped Venting Lines
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Solution Overview
Problem
Current leak detection systems for sealed fuel systems in vehicles fail to accurately detect leaks in systems with venting lines that form a sump, as liquid fuel can block vapor circulation, leading to undetected leaks and difficulties in managing fuel systems for leak detection and pressure sensor malfunctions.
Innovation Solution
A sealed fuel system with a leak detection device featuring two pressure sensors and a controller, where one sensor measures pressure in the vapor dome and the other measures pressure above the highest possible liquid level in the venting line, combined with a temperature sensor to enhance detection accuracy, allowing for reliable leak detection even when vapor volumes are unconnected, and a method that compares pressure and temperature measurements at predetermined intervals to determine if a leak is present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a venting line forms a sump to simplify assembly and reduce reinforcement needs, then ease of manufacture and weight are improved, but liquid fuel can block vapor circulation causing leak detection to fail
Solution Approach 1:
The vapor dome is divided into two separate measurement zones: one in the fuel tank vapor dome and another in the filler pipe vapor dome above the sump. This segmentation allows independent pressure monitoring in regions that may be disconnected by liquid blocking, ensuring leak detection reliability while maintaining the simple sump geometry for ease of manufacture
2Ease of manufacture
If additional holes are drilled in the vehicle frame to pass the venting line, then ease of manufacture is improved, but weight increases due to reinforcement pieces
Solution Approach 1:
The venting line is designed with flexible routing that can adapt to the vehicle frame structure without requiring fixed holes. The line can be routed through existing openings or flexible passages, eliminating the need for additional reinforcement pieces and associated weight while maintaining ease of installation
3Device complexity
If a single pressure sensor is used in the fuel tank vapor dome, then device complexity is reduced, but leak detection reliability deteriorates when vapor volumes are unconnected
Solution Approach 1:
The pressure monitoring function is segmented into two separate sensors placed in different vapor domes (fuel tank and filler pipe). This segmentation ensures that even if liquid fuel blocks the venting line and disconnects the vapor volumes, each sensor can independently detect pressure changes in its respective zone, maintaining leak detection reliability
Solution Approach 2:
The controller acts as an intermediary that receives and compares pressure signals from both sensors, along with temperature data. This intermediary processing enables the system to reliably detect leaks by analyzing pressure differential changes across the venting line, compensating for the increased device complexity through intelligent algorithmic mediation
4Reliability
If temperature sensors are added to enhance detection accuracy, then leak detection reliability is improved, but use of energy increases
Solution Approach 1:
Temperature sensors are activated periodically at predetermined intervals rather than continuously. The system performs periodic temperature measurements to calculate expected pressure changes based on thermal expansion, enabling accurate leak detection only when temperature data is needed. This periodic operation significantly reduces electrical consumption while maintaining detection reliability
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
The solution enables accurate leak detection in fuel systems with sump-shaped venting lines, reducing the need for additional reinforcement and weight, while also simplifying assembly and reducing electrical consumption by using two pressure sensors and a temperature sensor to assess pressure and temperature changes, ensuring reliable detection across various vehicle conditions.
Implementation Method 1
a first pressure sensor provided to measure the pressure in the vapor dome of the fuel tank
Implementation Method 2
a second pressure sensor to measure the pressure in the venting line above the highest possible liquid level that could be present in the venting line or to measure the pressure in the filler pipe above the highest possible liquid level that could be present in said filler pipe
Implementation Method 3
temperature is measured in addition to pressure inside the fuel vapor dome in order to related the two basic ways and determine whether there is a leak present
Implementation Method 4
relies on the evolution of temperature to build pressure inside the fuel tank based on the principle of the ideal gas law that relates a change in temperature in a sealed fuel system to a change in pressure in said system as a function of the amount of temperature change and the gas properties of the gaseous mixture inside the tank
Data Source
AI summary
The invention relates to a leak detection system on board of a vehicle comprising a fuel tank (301, 401), a filler pipe (302, 402), a venting line (303, 403) for recirculating fuel vapors from the tank to the filler pipe, said system having a combination pressure and temperature sensor mounted in the vapor dome of the fuel tank, and a pressure sensor located in the recirculation line above the highest possible liquid level that could be present in the recirculation line and to methods to detect said leak.