Aircraft Door Hinge Assembly with Programmable Linkage
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Solution Overview
Problem
Existing aircraft door hinge assemblies are complex, prone to stretching or flex, and require multiple components, leading to increased costs and rigging requirements, while chain systems face issues with tensioning, lubrication, and corrosion.
Innovation Solution
A hinge assembly utilizing three linkage rods and two pivot fittings with a combined Emergency Power Actuation System (EPAS)/Snubber cylinder, providing a programmable mechanical linkage for controlled door motion with adjustable links and simple components like rods, pins, and bearings, reducing complexity and component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing hinge assemblies use multiple fittings and links, then the door can be connected to the fuselage, but the linkage becomes complex and prone to stretching or flex
Solution Approach 1:
The hinge assembly is divided into distinct functional segments: a structural hinge for securing the door, a mechanical linkage with three specific links for motion control, and a pivot fitting for rotation. This segmentation allows each component to be optimized for its specific function while reducing overall complexity compared to monolithic designs.
Solution Approach 2:
The patent combines multiple functions into integrated components. The mechanical linkage integrates motion control, position control, and structural support into a unified system of three links and two pivot fittings, eliminating the need for separate tensioning, lubrication, and corrosion protection systems required by chain systems.
2Ease of operation
If chain systems are used for door linkage, then flexibility is provided, but issues with tensioning, lubrication, and corrosion arise
Solution Approach 1:
The patent replaces the chain system with a rigid mechanical linkage composed of three links and two pivot fittings. This substitution eliminates the need for lubrication and tensioning mechanisms while providing controlled door motion through geometric constraints rather than flexible chain connections.
Solution Approach 2:
The design changes from a flexible chain system to a rigid linkage system, fundamentally altering the mechanical parameters. The three-link mechanism provides the necessary flexibility for door motion control through its geometric configuration rather than through material flexibility, eliminating corrosion and lubrication requirements.
3Manufacturing precision
If complex machining or manufacturing practices are used, then precise door control is achieved, but component costs and fabrication difficulty increase
Solution Approach 1:
The patent applies precision only where necessary: the pivot fittings require precise machining to ensure smooth rotation and proper geometric constraints, while the links themselves can be fabricated using simpler methods. This localized approach to quality control achieves the required door position control without demanding complex manufacturing practices across all components.
Solution Approach 2:
The three-link mechanism provides dynamic door control through its geometric configuration, allowing the door to follow a programmed motion path. The system adapts to manufacturing tolerances through its kinematic design, reducing the need for ultra-precise fabrication while maintaining accurate door positioning throughout the opening sequence.
4Reliability
If multiple components are used in the hinge assembly, then the door can be securely connected, but the overall weight and installation complexity increase
Solution Approach 1:
Each component in the three-link mechanism serves multiple functions: the links provide structural support, motion control, and position constraint simultaneously. The pivot fittings provide rotation axes and geometric constraints. This multi-functionality reduces the total component count and weight compared to systems requiring separate elements for each function.
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 offers a lighter, easier-to-install design with improved motion control, reduced component costs, and elimination of issues associated with chain systems, such as tensioning and corrosion, while maintaining a rigid linkage for smooth door operation.
Implementation Method 1
three linkage rods and two pivot fittings are employed to create a programmable mechanical linkage between the rigid aircraft structure and the moving door structure
Implementation Method 2
The hinge also translates the door forward to provide a clear opening into the aircraft as the door swings away from the body
Implementation Method 3
The inclusion of the EPAS/snubber system in this manner should allow for simplification and possibly reduced costs of the EPAS components
Data Source
AI summary
A hinge assembly for attaching a door structure to an aircraft fuselage is provided. The door structure is linked to the aircraft body structure by way of a programmable mechanical linkage that is attached to the hinge member. The programmable mechanical linkage is actuated along the hinge member so as to maintain the door structure attached thereto in a controlled angular relationship relative to the longitudinal axis of the aircraft fuselage through its attachment to the fixed aircraft frame.