Fuel Filter Bypass Valve for On-Demand Wash Flow Control
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Solution Overview
Problem
Current fuel systems in aircraft do not provide sufficient filtered fuel to meet the needs of increasing numbers of actuators, leading to inefficiencies and reduced fuel availability for cleaning filters, and traditional systems waste fuel on continuous washing flows.
Innovation Solution
A fuel filter system with a bypass valve that opens when a predetermined pressure drop occurs, allowing filtered fuel to be directed for cleaning the filter when needed and sealing the washing path when not required, thereby optimizing fuel usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous bypass flow is used to clean the filter, then the filter remains clean, but fuel is wasted and filtered fuel availability decreases
Solution Approach 1:
The bypass valve operates periodically rather than continuously, opening only when the pressure differential across the filter reaches a predetermined threshold. This periodic operation cleans the filter only when necessary, eliminating continuous fuel waste while maintaining filter cleanliness through on-demand washing cycles.
Solution Approach 2:
The system uses the engine's own fuel pressure differential to automatically trigger the bypass valve opening. When the filter becomes clogged and pressure differential increases, the system self-activates the cleaning function without external control, using the problem condition itself as the trigger for the solution.
2Reliability
If continuous bypass flow is used to clean the filter, then the filter remains clean, but the number of filtered fuel available for actuators decreases
Solution Approach 1:
The bypass valve opens periodically only when the pressure differential threshold is reached, rather than remaining open continuously. This ensures that filtered fuel is diverted for cleaning only when the filter performance degrades, maximizing the quantity of filtered fuel available for actuators during normal operation while maintaining filter cleanliness.
3Reliability
If a pressure regulating bypass valve is used, then flow can be bypassed to drain, but additional flow is introduced under normal operation
Solution Approach 1:
The invention extracts the bypass function from a continuously operating pressure regulating valve and implements it as a demand-activated mechanism. The bypass path is taken out of the normal flow circuit and only activated when the pressure differential across the filter reaches a threshold, preventing unnecessary fuel flow diversion while maintaining filter protection capability.
Solution Approach 2:
The bypass valve acts as an intermediary element that mediates between the filter and the drain, opening only when necessary. This intermediary component controls the bypass flow based on the actual need, preventing direct continuous connection that would cause unnecessary fuel flow loss while ensuring filter protection when needed.
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
Enhances the availability of filtered fuel for actuators by maintaining filter cleanliness without unnecessary washing flows, improving system efficiency and reducing fuel waste.
Implementation Method 1
When the pressure drop across the filter increases the bypass valve opens to allow fuel to flow across the filter cleaning the debris
Data Source
AI summary
A dual variable displacement pump having an actuation pump sub-system (APS) with an inlet configured to feed fuel from a fuel source into the APS, a first outlet configured for connecting the APS in fluid communication with an actuation system to supply filtered fuel for actuation. The APS has a first pump with a pump inlet in fluid communication with the fuel source, and a pump outlet connected to the third outlet of the APS. The APS further has an actuation filter between the pump outlet of the first VDP with an outlet of the APS. The fuel filter has an input, an output and a washing path. The fuel filter may be cylindrical in shape. The system further comprising a bypass valve having an input from the washing path, and a drain, wherein when the cylindrical fuel filter has a pressure drop from the input to the output, the bypass valve opens to permit cleaning of the filter by allowing fuel to flow from the washing path to the drain. The bypass valve comprises a spool, a valve seat and a spring that has a spring rate (Sk). The output may be provided through an input to the bypass valve, behind the spool.