Fuel Tank Venting System Liquid Separation
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Solution Overview
Problem
Existing fuel tank designs are complex and insufficient in separating liquid fuel from fuel gas during refueling, particularly when flow ducts have small cross sections and high flow velocities, leading to liquid carry-over issues.
Innovation Solution
A fuel tank design where the operational and refueling venting lines are combined and communicate with a fuel vapor filter, with a filler pipe that forms a swirl volume to separate liquid hydrocarbons from fuel gas, and includes a valve that prevents liquid hydrocarbons from entering the venting path during refueling, using a pivotally supported valve body and a dividing wall as a droplet separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the flow ducts are designed with small cross sections, then the fuel tank structure is compact, but the flow velocities of the fuel gases become relatively high, making it difficult to separate liquid carry-over from the volumetric flow of fuel gas
Solution Approach 1:
The venting system is segmented into separate operational venting and refueling venting paths. The operational venting line includes a dedicated swirl pot for liquid separation, while the refueling venting line has its own drainage arrangement. This segmentation allows each path to be optimized for its specific function without compromising the other.
Solution Approach 2:
A multi-way valve at the filler head acts as an intermediary that directs fuel gases through different paths depending on the operating state. During refueling, it directs gases through the refueling venting line with drainage; during operational venting, it directs gases through the operational venting line with swirl pot separation.
2Reliability
If separate venting lines are provided for refueling and operational venting, then the venting functions are well-defined, but the design becomes relatively complex and additional measures are needed for liquid separation
Solution Approach 1:
The operational and refueling venting lines are merged into a common downstream path that leads to a shared fuel vapor filter. This merging reduces the number of separate components and simplifies the overall system architecture while maintaining distinct upstream paths for liquid separation and drainage.
Solution Approach 2:
The fuel vapor filter serves as a universal component that handles both operational venting vapors and refueling vapors. The multi-way valve provides multi-functionality by switching between different venting paths based on operating conditions.
3Ease of manufacture
If a fuel drainage is provided in the refueling duct, then some liquid separation is achieved, but it is not sufficient to separate liquid carry-over from the volumetric flow of fuel gas without additional measures
Solution Approach 1:
Instead of relying solely on vertical drainage, the invention introduces a swirl pot that utilizes rotational motion (adding a dimensional aspect to the separation process). The swirl pot creates centrifugal forces that enhance liquid-gas separation beyond what simple gravity drainage can achieve.
Solution Approach 2:
The swirl pot changes the flow parameters of the fuel gas by inducing rotation and reducing flow velocity. This parameter change allows liquid droplets to separate from the gas stream more effectively before the vapors enter the fuel vapor filter.
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 design effectively separates liquid hydrocarbons from fuel gas, reducing the need for additional measures like swirl pots and ensuring efficient vapor filtration without overloading the fuel vapor filter, by utilizing the filler pipe as a liquid trap and conducting operational venting flow through the refueling duct to the fuel vapor filter.
Implementation Method 1
the filler pipe itself advantageously serves to receive the liquid carry-over in dynamic running, that is to say in the operational state of the motor vehicle. According to the invention the filler pipe in the operational venting path forms a swirl volume, which with the aid of the expanded volume of the filler pipe allows liquid hydrocarbon to be separated from the fuel gas.
Implementation Method 2
in any switching position of the valve it communicates with a downstream fuel vapor filter connected to the filler head
Data Source
AI summary
The invention relates to a fuel tank having at least one filler pipe (2) enclosing a refueling duct (13), at least one operational venting valve (11), at least one refueling venting valve (8) and at least one venting line (9), which is connected to a filler head (3) of the filler pipe (2). The filler head (3) comprises a valve, which when refueling closes a flow path from the venting line (9) into the refueling duct (13). One of outstanding features of the fuel tank is that the venting line (9) is embodied as a collective venting line for the refueling and operational venting and that in any switching position of the valve it communicates with a downstream fuel vapor filter (10) connected to the filler head (3).