Passive Fuel Separator Aspiration via Negative Pressure
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Solution Overview
Problem
Conventional fuel systems for combustion engines face challenges in efficiently draining liquid fuel from a liquid separator without requiring a fuel pump or jet pump, and in mounting the liquid separator within the fuel tank or above it, which complicates the design and increases costs.
Innovation Solution
A fuel system design where the liquid separator is positioned such that its fuel port is at a lower elevation than the fuel tank's vent opening, allowing liquid fuel to be passively aspirated back into the tank under negative pressure conditions, eliminating the need for a pump and allowing flexible mounting inside or outside the tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fuel pump or jet pump is used to drain liquid fuel from the liquid separator, then liquid fuel can be effectively discharged from the liquid separator, but the device complexity and manufacturing cost increase
Solution Approach 1:
The liquid separator utilizes the vehicle's own negative pressure conditions during fuel tank operation to automatically aspirate and drain liquid fuel from the separator. The system serves itself by using the existing pressure differential created during normal fuel tank venting and fuel delivery operations, eliminating the need for external pumping mechanisms while maintaining reliable liquid drainage.
Solution Approach 2:
The patent replaces the mechanical pumping system with a pressure-driven aspiration system. Instead of using a fuel pump or jet pump to mechanically force liquid fuel from the separator, the system uses the natural negative pressure conditions that occur during fuel tank operation to draw liquid fuel through the separator and into the fuel tank, substituting a mechanical system with a pressure-based system.
2Device complexity
If the liquid separator is mounted inside or above the fuel tank, then liquid fuel can drain by gravity, but the device complexity and space requirements increase
Solution Approach 1:
The liquid separator employs pneumatic pressure differentials to achieve liquid fuel drainage. By positioning the fuel port at a lower elevation than the vent opening and utilizing negative pressure conditions within the fuel tank, the system creates a pressure gradient that aspirates liquid fuel from the separator into the tank, eliminating the need for gravity-dependent mounting configurations.
Solution Approach 2:
The patent changes the mounting flexibility by using pressure-driven flow instead of gravity-driven flow. This allows the liquid separator to be mounted in various positions (inside or outside the fuel tank) without requiring specific orientation or elevation relationships, as the negative pressure aspiration can draw liquid fuel regardless of the separator's vertical position relative to the tank.
3Reliability
If the liquid separator is positioned at a lower elevation than the vent opening, then passive aspiration can occur, but the available mounting space is reduced
Solution Approach 1:
The liquid separator design provides universal mounting capability by accepting various installation positions and orientations. The separator can be mounted inside or outside the fuel tank at different elevations, as the negative pressure aspiration system adapts to the available space and mounting configuration, making the system versatile for different vehicle applications and fuel tank designs.
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 simplifies the system, reduces manufacturing and assembly costs, enhances durability and reliability, and ensures a long service life by enabling passive aspiration of liquid fuel without the need for additional pumping mechanisms.
Implementation Method 1
The liquid separator is in fluid communication with the at least one vent in the fuel tank and has a fuel port disposed at a lower elevation than the at least one vent to enable the liquid fuel in the liquid separator to be passively aspirated under negative pressure conditions within the fuel tank
Data Source
AI summary
A fuel system includes a fuel tank and a liquid separator. The fuel tank includes an interior in which liquid fuel and fuel vapor are contained, and has at least one vent in fluid communication with a vapor dome in the interior of the fuel tank. The liquid separator is in fluid communication with the at least one vent in the fuel tank, and has a fuel port disposed at a lower elevation than the at least one vent to enable the liquid separator to be passively aspirated under negative pressure conditions within the fuel tank. The liquid separator may be placed inside or outside the fuel tank.