Aircraft Door Stop Pin Assembly with Inverted Spherical Interface
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Solution Overview
Problem
Conventional aircraft door stop pin assemblies face issues with misalignment and require additional components like wires for conductivity, leading to increased length and weight due to incompatible design envelopes and the need for lubrication.
Innovation Solution
A door stop pin assembly with a pin having a concave spherical recess and a base pad with a complementary convex surface, allowing for conductive communication and reduced base pad height, eliminating the need for separate wires and lubrication, and enabling misalignment while providing a positive stop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional threaded stop pin with convex spherical head and mating concave base pad is used, then the door stop provides load transmission and misalignment compensation, but the base pad height is incompatible with present design envelopes and requires additional wire components for conductivity
Solution Approach 1:
The patent inverts the conventional configuration by placing the concave spherical recess on the pin instead of the base pad, and the convex spherical portion on the base pad instead of the pin. This inversion allows the base pad height to be reduced to fit within present design envelopes while maintaining the spherical interface for load transmission and misalignment compensation.
Solution Approach 2:
The patent combines multiple functions into the base pad structure itself. The base pad now provides both the spherical contact interface for mechanical function and the conductive path for electrical continuity, eliminating the need for separate wire components. The reduced height base pad integrates structural support, spherical interface, and electrical conductivity in a single compact component.
2Reliability
If lubrication is used between contact surfaces of the pin and base pad, then fretting and galling are prevented, but additional wire components are required for conductivity and the assembly becomes more complex
Solution Approach 1:
The patent merges the lubrication function and electrical conductivity function into a single integrated solution. The reduced height base pad structure allows the lubricated contact surfaces to directly provide both friction reduction and electrical continuity, eliminating the need for separate wire components and reducing overall assembly complexity.
Solution Approach 2:
The base pad structure is designed to serve multiple functions simultaneously - it provides structural support, spherical interface for misalignment compensation, conductive path for electrical continuity, and lubricated contact surfaces for preventing fretting and galling. This self-service approach eliminates the need for additional wire components.
3Weight of stationary object
If the base pad height is reduced to fit tight design envelopes, then weight and size constraints are improved, but the spherical interface geometry becomes more difficult to manufacture
Solution Approach 1:
The patent inverts which component carries the concave spherical feature. By placing the concave recess on the pin (which has adequate length) and the convex portion on the reduced height base pad, the manufacturing complexity is shifted to the pin where there is sufficient space, while the base pad remains compact for weight and size optimization.
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 reduces base pad height by 30% compared to conventional designs, enabling smaller, lighter assemblies that can fit in tight spaces and eliminate the need for additional components, enhancing aerospace applications by reducing weight and size constraints while providing a conductive path for static discharge.
Implementation Method 1
The pin has a concave spherical recess. And, the base pad has an open end and a closed end such that the open end has a convex spherical portion in contact with the concave spherical recess
Implementation Method 2
The base pad and pin configuration provides a conductive path between the two
Data Source
Figure 1~3
AI summary
Disclosed herein is a door stop pin assembly including a pin and a base pad. The pin has a concave spherical recess. And, the base pad has an open end and a closed end such that the open end has a convex spherical portion in contact with the concave spherical recess.