Fail-Safe Hinge Pin Assembly for Tool-Less Tight Installation
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Solution Overview
Problem
Existing hinged assemblies in aircraft propulsion systems lack a fail-safe mechanism to prevent structural failure and require large tools for installation, leading to potential loosening and restricted accessibility.
Innovation Solution
A hinged assembly with a fail-safe hinge pin design featuring an inner pin loosely fitted within an outer pin, secured by collars and fasteners that allow for tool-less installation and prevent loosening, while providing a backup in case of outer pin failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional hinge pin design is used, then the structure is simple, but it lacks fail-safe mechanism and may loosen during operation
Solution Approach 1:
The hinge pin is divided into two separate pins (first hinge pin and second hinge pin) that work together. Each pin is secured by its own collar and fastener assembly, creating independent fail-safe mechanisms. If one pin fails, the other remains functional, providing redundancy and preventing complete hinge failure.
Solution Approach 2:
The collars are positioned on the outer surface of the hinge pins, with fasteners projecting through the collars to secure the pins. This nested arrangement allows multiple components (pin, collar, fastener) to work together in a compact configuration that provides both security and fail-safe functionality without excessive complexity.
2Ease of manufacture
If large tools are used for installation, then the fastening is secure, but accessibility is restricted and installation is difficult
Solution Approach 1:
The collar and fastener assembly is designed to be self-contained and self-securing. The fastener projects through the collar and engages with the hinge pin in a way that automatically maintains tightness and prevents loosening during operation, eliminating the need for continuous tool intervention or large installation tools.
Solution Approach 2:
Instead of using large tools to continuously tighten and secure the hinge pin during operation, the design inverts the approach by using a pre-installed collar and fastener assembly that maintains security passively. The fastener geometry is designed to prevent loosening through operational vibrations and movements without requiring active tool intervention.
3Stability of the object's composition
If the hinge pin is secured tightly, then the assembly remains tight, but it requires anti-rotation features that complicate the design
Solution Approach 1:
The collar is designed with an asymmetric geometry relative to the hinge pin, with the fastener projecting through specific positions on the collar. This asymmetric arrangement creates inherent resistance to rotation and loosening forces without requiring additional anti-rotation features, as the fastener-collarpin geometry itself prevents rotational movement that would cause loosening.
4Reliability
If a single hinge pin is used, then the structure is simple, but it lacks backup in case of failure
Solution Approach 1:
The hinge connection is segmented into two independent hinge pins rather than using a single pin. Each pin has its own collar and fastener assembly, creating redundant load paths. If one pin fails due to fatigue, corrosion, or other degradation, the second pin continues to provide structural support, preventing catastrophic hinge failure and allowing for safe operation or controlled shutdown.
Data Source
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AI summary
A pin assembly is provided with an axial centerline (18). This pin assembly includes an outer pin (38), an inner pin (40), a first collar (42A) and a second collar (42B). The outer pin extends axially along the axial centerline between an outer pin first end (48) and an outer pin second end (50). The inner pin extends axially along the axial centerline within a bore (52) of the outer pin. The first collar circumscribes the outer pin. The first collar is connected to the outer pin and the inner pin at the outer pin first end. The second collar circumscribes the outer pin. The second collar is connected to the outer pin and the inner pin at the outer pin second end.