Aircraft Engine Spool Valve Structure to Prevent Jamming
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Solution Overview
Problem
Existing aircraft engine valves experience force imbalances leading to jamming, which can cause undesirable oil leakage during startup due to insufficient air pressure, especially in bearing cavities.
Innovation Solution
A spool valve design with a spool movably received within a housing, featuring a valving section, guiding section, and apertured section, and a biasing member to maintain a closed position, along with a sleeve and adjustment member to manage pressure imbalances, ensuring smooth operation and reduced jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional valve design is used, then the structure is simple, but force imbalances occur leading to jamming and oil leakage
Solution Approach 1:
The spool is divided into three distinct sections: a valving section with sealing surfaces, a guiding section for precise positioning, and an apertured section for fluid communication. This segmentation allows each section to perform its specific function optimally, preventing force imbalances and jamming while maintaining reliable operation.
Solution Approach 2:
The biasing member acts as an intermediary element that applies a balancing force to the spool, counteracting pressure imbalances between the inlet and outlet sides. This mediator prevents the spool from sticking in the closed position due to force imbalances, ensuring reliable valve operation without requiring complex additional mechanisms.
2Reliability
If the spool is biased to closed position, then oil leakage is prevented, but the valve may jam due to force imbalances
Solution Approach 1:
The biasing member provides a counterbalancing force that opposes the pressure differential across the spool. This counterforce prevents the spool from becoming stuck in the closed position by compensating for sealing forces, allowing smooth operation while maintaining reliable sealing when closed.
Solution Approach 2:
The valving section is specifically designed with sealing surfaces that engage only when the spool is in the closed position, while the guiding section provides continuous support. This localized sealing quality ensures reliable oil containment without creating excessive friction or jamming throughout the entire spool length.
3Reliability
If air pressure is insufficient during startup, then the valve should remain closed to prevent leakage, but force imbalances cause jamming
Solution Approach 1:
The biasing member is pre-loaded to apply a balancing force to the spool before startup conditions are fully established. This preliminary counteraction prevents the spool from jamming in the closed position even when air pressure is insufficient, ensuring the valve can transition smoothly to the open position when needed while preventing leakage during normal 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
The spool valve effectively mitigates jamming and ensures controlled oil flow to engine components, minimizing leakage and maintaining operational efficiency by balancing pressure forces.
Implementation Method 1
a biasing member biasing the spool to the closed position
Implementation Method 2
the spool moveable between: a closed position in which the valving section overlaps the outlet and in which the spool blocks fluid communication between the inlet and the outlet, and an open position in which the valving section is offset from the outlet and in which the inlet is fluidly connected to the outlet
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A valve (60; 360; 460) has: a housing (61; 461) defining an internal cavity circumscribed by a peripheral wall (61C) extending between a first end (61A) and a second end (61B) and having an outlet (600; 3600; 4600) and an inlet (60I); a spool (62; 162; 262; 362; 462) having a valving section (62A) sealingly engaged to the peripheral wall (61C) between the outlet (600; 3600; 4600) and the second end (61B), a guiding section (62B) sealingly engaged to the peripheral wall (61C) between the outlet (600; 3600; 4600) and the first end (61A), and an apertured section (62C) defining apertures (62D), the spool (62...462) moveable between: a closed position in which the valving section (62A) overlaps the outlet (600; 3600; 4600) and in which the spool (62...462) blocks fluid communication between the inlet (60I) and the outlet (600; 3600; 4600), and an open position in which the valving section (62A) is offset from the outlet (600; 3600; 4600) and in which the inlet (60I) is fluidly connected to the outlet (600; 3600; 4600) through the one or more apertures (62D) of the apertured section (62C) of the spool (62...462); and a biasing member (63) biasing the spool (62...462) to the closed position.