Aircraft Fuel Transfer System with Float Valves
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Solution Overview
Problem
Aircraft fuel systems face challenges in managing fuel pressure and maneuver loads, particularly during vertical acceleration, which requires additional reinforcement and complex fuel management systems when upper and lower tanks are hydraulically connected.
Innovation Solution
A fuel transfer system with an upper tank and a lower tank connected by a fuel transfer line, featuring upper and lower float valves that allow gravity-driven fuel transfer, isolating hydraulic pressure and simplifying fuel management by controlling fuel levels through sequential volume reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If upper and lower tanks are hydraulically connected to allow gravity-driven fuel transfer, then fuel management is simplified and additional reinforcement to the lower fuel tank structure is avoided, but fuel pressure increases proportionately with vertical acceleration during maneuvers
Solution Approach 1:
The patent introduces a break tank as an intermediary component between the upper and lower fuel tanks. This break tank acts as a hydraulic separator that interrupts the direct hydraulic connection while still allowing gravity-driven fuel transfer. The break tank contains a float valve mechanism that controls fuel flow, enabling the system to maintain simplified gravity-based fuel management without transmitting full hydraulic pressure loads from the upper tank to the lower tank structure during vertical maneuvers.
2Stress or pressure
If a shutoff valve is used to disconnect two tanks, then fuel pressure on the lower tank structure is reduced, but level sensors and manual or automatic electronic control devices are required making the fuel management system more complicated
Solution Approach 1:
The patent employs a float valve mechanism within the break tank that automatically controls fuel transfer between upper and lower tanks based on fuel level conditions. The float valve self-regulates the hydraulic connection and disconnection without requiring external sensors, electronic controls, or manual intervention. This self-service mechanism achieves pressure management while maintaining simple fuel management system architecture.
3Strength
If additional reinforcement is applied to the lower fuel tank structure to withstand high acceleration conditions, then the tank can handle increased fuel pressure, but the aircraft structure weight increases
Solution Approach 1:
By introducing the break tank as a hydraulic intermediary, the system prevents full hydraulic pressure transmission to the lower tank structure during vertical maneuvers. This allows the lower tank to be designed with standard structural reinforcement rather than additional heavy reinforcement, thereby maintaining sufficient strength while avoiding unnecessary weight increase in the aircraft structure.
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 system effectively manages fuel pressure and maneuver loads by allowing controlled fuel transfer through gravity, reducing the need for additional reinforcement and simplifying fuel management, while maintaining a stable center of gravity and efficient fuel consumption.
Implementation Method 1
an upper float valve associated with the upper fuel transfer line outlet, and a lower float valve associated with the lower fuel transfer line outlet
Implementation Method 2
allowing gravity-driven fuel transfer
Data Source
Figure 1
Figure 2~5
Figure 3A~3F
AI summary
A fuel transfer system for an aircraft includes an upper tank, a lower tank, a fuel transfer line connecting the upper tank to the lower tank, an upper fuel transfer line outlet in the lower tank, a lower fuel transfer line outlet in the lower tank, an upper float valve associated with the upper fuel transfer line outlet, and a lower float valve associated with the lower fuel transfer line outlet. The upper fuel transfer line outlet, which is in the lower tank, is in fluid communication with the upper tank. The lower fuel transfer line outlet, which is located in the lower tank, is in fluid communication with the upper tank.