Fuel Tank Siphon Venting Prevents Overfill
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Solution Overview
Problem
Conventional liquid containers for motor vehicles, such as fuel tanks, face challenges in maintaining a pressure-holding function during filling operations to prevent overfilling and ensure proper ventilation, which is complicated and often results in undesired filling of the equalizing volume due to user error or design limitations, particularly when the container is tilted or in the US market where all displaced gas is discharged to the atmosphere.
Innovation Solution
The operational ventilation line is connected to the filler tube below the nozzle's outlet, forming a siphon that allows ventilation counter to the liquid column during filling, ensuring a pressure-holding function without additional valves or movable parts, and separate ventilation paths are provided for operational and filling ventilation, with the filler tube configured to allow liquid accumulation and automatic draining during vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filling ventilation valve is equipped with a pressure-holding function using spring-loaded valve bodies or switchover valves, then overfilling prevention is ensured, but the device complexity increases and systematic filling of the equalizing volume may still occur
Solution Approach 1:
The invention extracts the pressure-holding function from complex valve mechanisms and relocates it to the siphon structure itself. The siphon's inherent liquid column creates the pressure barrier, eliminating the need for spring-loaded valve bodies or switchover valves while maintaining overfilling prevention reliability.
Solution Approach 2:
The siphon structure serves itself by using its own liquid column to create the pressure-holding effect. The liquid in the siphon automatically prevents equalizing volume filling when the liquid level rises, without requiring external control mechanisms or additional components.
2Reliability
If the operational ventilation line is positioned above the liquid level, then ventilation is maintained during operation, but liquid may enter the ventilation line during filling operations
Solution Approach 1:
The siphon acts as an intermediary between the operational ventilation line and the filler tube. It allows the ventilation line to remain positioned for optimal operational ventilation while preventing liquid from directly entering the ventilation line during filling, as the siphon's liquid column creates a barrier.
Solution Approach 2:
The invention uses hydraulic principles by positioning the operational ventilation line to utilize the liquid column in the siphon as a barrier. The liquid column creates a pressure differential that prevents liquid from entering the ventilation line while allowing gas to pass through during normal operation.
3Stress or pressure
If the equalizing volume is ventilated during filling operations, then pressure build-up is prevented, but the filling operation cannot be properly detected and overfilling may occur
Solution Approach 1:
The invention segments the ventilation function into two separate paths: filling ventilation through the filling ventilation valve and operational ventilation through the operational ventilation line. This segmentation allows the operational ventilation line to remain closed during filling (enabling proper detection) while still providing pressure relief through the dedicated filling ventilation path.
Solution Approach 2:
The system dynamically switches between filling ventilation and operational ventilation modes. During filling, the operational ventilation line is closed by the liquid column in the siphon, enabling proper filling level detection. When filling is complete and the liquid level drops, the operational ventilation line opens to maintain pressure balance during vehicle operation.
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 solution simplifies the pressure-holding function, ensuring reliable operational ventilation and filling switch-off, maintaining a pressureless state during vehicle operation by selecting the cross-sectional ratio of the operational ventilation line to the filler tube, preventing overfilling and ensuring effective gas discharge through a fuel vapour filter.
Implementation Method 1
The operational ventilation line is connected to the filler tube below the outlet-side end of the nozzle which is pushed into the filler tube, in such a way that a part flow of the liquid passes into the operational ventilation line and accumulates in the siphon which is formed by the operational ventilation line.
Implementation Method 2
ventilation of the container via the operational ventilation line can take place only counter to the liquid column which is present in the siphon. As a result, a pressure-holding function is ensured by way of very simple means.
Implementation Method 3
the gas volume which accumulates on account of driving dynamics and temperature changes above the liquid level will be discharged out of the liquid container to the atmosphere via a fuel vapour filter which is configured as an activated charcoal filter.
Data Source
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Figure 2
AI summary
The invention relates to a liquid container (1 ) for a motor vehicle, in particular a fuel container (1 ), having at least one filler tube (4) and having means for operational and filling ventilation, comprising at least one operational ventilation line (7) which is connected to an equalizing volume of the liquid container (1 ) and at least one filling ventilation opening (9) which opens into the equalizing volume. The fuel container (1 ) according to the invention is distinguished by the fact that the operational ventilation opening (7) is connected to the filler tube (4) outside the container volume, in a manner which forms a siphon (8), and that the connection of the operational ventilation line (7) to the filler tube (4) is arranged in such a way that liquid is collected in the siphon (8) during each filling operation and closes the operational ventilation line (7).