Aircraft Door Piston Assembly with Gear Locking for Pressure Loss
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Solution Overview
Problem
Existing aircraft door piston assemblies face difficulties in maintaining partial opening or closing due to hydraulic fluid pressure loss, leading to unintended full retraction of doors when hydraulic fluid leaks around worn piston seals.
Innovation Solution
A piston assembly design featuring a piston housing with a screw shaft and slider mechanism, where gears engage to prevent translation when fluid pressure stalls, allowing controlled translation and rotation to manage door opening and closing, utilizing biasing members and flow control valves to maintain position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional piston assembly is used for aircraft door actuation, then the door can be fully deployed and retracted under hydraulic pressure, but the door cannot be maintained in a partially opened position due to hydraulic fluid leakage around worn piston seals
Solution Approach 1:
The piston assembly is segmented into two distinct functional modes: a translation mode where the piston shaft moves linearly to deploy/retract the door, and a rotation mode where the screw shaft rotates to lock the door in position. This segmentation allows the system to achieve both full door actuation and stable partial position maintenance by separating the motion functions into distinct mechanical phases
Solution Approach 2:
The system dynamically transitions between two operational states based on hydraulic pressure conditions. When hydraulic fluid is supplied, the piston shaft translates forward to open the door. When fluid is removed, the screw shaft rotates to lock the door at the achieved position. This dynamic state transition allows the door to be opened and then securely held at any intermediate position without requiring continuous hydraulic pressure
2Reliability
If hydraulic fluid is supplied continuously to maintain door position, then the door can remain in position, but hydraulic fluid leaks around worn piston seals causing unintended door closure
Solution Approach 1:
The invention replaces the continuous hydraulic pressure maintenance system with a mechanical locking system. Instead of relying on continuous hydraulic fluid supply to hold the door position, the screw shaft mechanism converts the achieved position into a mechanically locked state through rotation, eliminating the need for continuous hydraulic pressure and preventing fluid leakage issues
3Reliability
If a mechanical locking mechanism is added to prevent door drift, then door position stability is improved, but device complexity increases
Solution Approach 1:
The invention merges the actuation function and the locking function into a single integrated piston assembly. The same hydraulic system that drives the piston shaft for door deployment also drives the screw shaft for locking. By combining these functions in one assembly rather than adding a separate locking mechanism, the patent achieves reliable door position stability while minimizing additional structural complexity
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
Enables precise control over aircraft door movement, preventing unintended full retraction and allowing secure locking of doors in partially opened or closed positions, even with hydraulic fluid pressure fluctuations.
Implementation Method 1
Power doors for aircraft may be actuated by piston assemblies that operate under hydraulic pressure
Implementation Method 2
a first biasing member extends from the piston housing aft end to engage the slider
Data Source
AI summary
Disclosed is an aircraft piston assembly, having: a piston housing fluid port formed in a piston housing; a piston shaft, disposed within the piston housing, configured for translation in either forward or aft directions when fluid is respectively supplied to or removed from the piston housing; a screw shaft, disposed within the piston housing, that includes a first gear that rotates without translation while the piston shaft translates; and a slider, disposed within the piston housing, that includes a second gear, and that is configured for translation without rotation, wherein: the slider moves between a first position where the first gear and the second gear are separated from one another to allow the piston shaft to translate and a second position where the second gear surrounds the first gear so that the first and second gears are engaged with one another and the piston shaft is prevented from translating.