Aircraft Door Piston Assembly With Mechanical Locking for Pressure Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aircraft door piston assemblies struggle with partial opening and closing due to hydraulic fluid pressure loss, leading to unintended door closure when hydraulic fluid leaks around worn piston seals.
Innovation Solution
A piston assembly design featuring a screw-nut pair with dog gears that allows translation in either direction while preventing rotation, and a slider mechanism with biasing members to manage fluid pressure and maintain gear engagement, enabling precise control over door movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fluid is supplied to the piston housing to deploy the door, then the door can be opened, but hydraulic fluid leakage around worn piston seals causes pressure loss and unintended door closure
Solution Approach 1:
The system dynamically transitions between two operational modes: during door movement, the dog gears are disengaged allowing free rotation of the screw shaft; when door position needs to be held, the dog gears engage to lock the screw shaft and prevent rotation. This dynamic switching resolves the contradiction by maintaining reliability without continuous hydraulic pressure.
Solution Approach 2:
The patent replaces the purely hydraulic positioning system with a mechanical locking system using dog gears and a slider mechanism. The mechanical engagement of the dog gears with the screw shaft teeth provides a positive lock that maintains door position independently of hydraulic pressure, substituting mechanical force for hydraulic pressure in the position-holding function.
2Reliability
If a mechanical locking mechanism is added to prevent unintended door closure, then door position stability improves, but device complexity increases
Solution Approach 1:
The slider mechanism serves multiple functions: it acts as a seal against the piston shaft, provides the mechanical linkage for the dog gear engagement, and controls the biasing member that positions the dog gears. By combining these functions into a single component, the patent adds mechanical locking capability while minimizing the increase in overall device complexity.
Solution Approach 2:
The dog gears are nested within the piston assembly structure, with the first dog gear attached to the screw shaft and the second dog gear integrated with the slider. The biasing member is nested within the piston housing, engaging the slider from the rear. This nested arrangement minimizes space requirements and integrates the locking mechanism into the existing piston assembly geometry.
3Ease of operation
If the piston shaft is allowed to translate freely in both directions for door operation, then ease of operation improves, but control precision deteriorates due to inability to maintain partial positions
Solution Approach 1:
The system dynamically transitions between two operational modes: during door movement, the dog gears are disengaged allowing free rotation of the screw shaft; when door position needs to be held, the dog gears engage to lock the screw shaft and prevent rotation. This dynamic switching resolves the contradiction by maintaining reliability without continuous hydraulic pressure.
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 solution ensures stable and precise control over aircraft door opening and closing, preventing unintended closure due to hydraulic pressure fluctuations and maintaining partial positions effectively.
Implementation Method 1
Power doors for aircraft may be actuated by piston assemblies that operate under hydraulic pressure
Implementation Method 2
a screw shaft disposed within the piston housing, wherein the screw shaft includes a first gear that rotates without translation in either the forward or aft directions while the piston shaft translates in either the forward or aft directions such that the screw and piston shafts are configured as a screw-nut pair
Implementation Method 3
the first gear and the second gear are dog gears that extend radially toward one another, and wherein the slider is configured for translation in either the forward or aft directions without rotation due to pressure within the piston housing
Implementation Method 4
a slider disposed within the piston housing, wherein the slider includes a second gear, wherein the first gear and the second gear are dog gears that extend radially toward one another
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is an aircraft piston assembly (100), having: a piston housing fluid port (1110) formed in a piston housing (110); a piston shaft (120), disposed within the piston housing (110), configured for translation in either forward or aft directions when fluid is respectively supplied to or removed from the piston housing (110); a screw shaft (130), disposed within the piston housing (110), that includes a first gear (140) that rotates without translation while the piston shaft translates; and a slider (150), disposed within the piston housing (110), that includes a second gear (160), and that is configured for translation without rotation, wherein: the slider (150) moves between a first position where the first gear (140) and the second gear (160) are separated from one another to allow the piston shaft to translate and a second position where the second gear (160) surrounds the first gear (140) so that the first and second gears (140,160) are engaged with one another and the piston shaft (120) is prevented from translating.