Self-Engaging Fan Cowl Hook Latch for Single-Person Operation
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Solution Overview
Problem
Modern aircraft nacelle systems with long, small-diameter fan cowls pose difficulties in opening and closing, requiring significant effort and often necessitating multiple persons to operate the latch mechanisms for securing the upper and lower fan cowls.
Innovation Solution
A latch mechanism featuring a latch frame, pivotally mounted latch arm, and a bias member that applies a load transverse to the pivot axis, with stops to control rotational directions, allowing single-person operation by engaging a mating pin and ensuring secure locking of the fan cowls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional latch mechanisms are used on long, small-diameter fan cowls, then the fan cowls can be securely locked, but the operation requires significant effort and multiple persons
Solution Approach 1:
The latch arm is designed to automatically engage with the mating pin through its own biased movement. When the fan cowl is closed, the latch arm's bias member automatically pushes the latch arm into the engaged position with the mating pin, eliminating the need for manual intervention or multiple persons to secure the locking mechanism.
Solution Approach 2:
The latch mechanism incorporates a movable latch arm that can dynamically transition between engaged and disengaged states. The latch arm pivots about an axis and is biased by a spring member, allowing it to automatically move into the engaged position when force is applied to close the fan cowl, and can be easily disengaged by applying force in the opposite direction.
2Ease of operation
If a biased latch arm is used to enable single-person operation, then ease of operation is improved, but additional components (bias member, stops) increase device complexity
Solution Approach 1:
The latch arm serves multiple functions: it acts as the primary locking element that engages with the mating pin, serves as a lever that can be manually operated, and works in conjunction with the bias member to automatically position itself. The first and second stops work together to define the operational range, with each stop serving a specific function in controlling the latch arm's movement.
3Reliability
If stops are added to control latch arm rotation, then operational reliability is improved, but the number of components and assembly complexity increases
Solution Approach 1:
The first and second stops are positioned asymmetrically relative to the latch arm's pivot axis. The first stop is located at a first longitudinal position and the second stop at a second longitudinal position, creating an asymmetric arrangement that effectively controls the latch arm's rotational range. This asymmetric positioning allows the stops to work together with the biased latch arm to provide reliable positioning without requiring symmetric or redundant components.
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
Facilitates single-person operation for opening and closing the nacelle, enhancing accessibility and reducing operational effort while ensuring secure locking of the fan cowls, thereby improving safety and efficiency.
Implementation Method 1
a bias member configured to apply a load to the latch arm in a transverse direction generally perpendicular to the pivot axis and to bias the latch arm from rotating in a first rotational direction about the pivot axis and from rotating away from the mating pin
Data Source
AI summary
A latch mechanism configured to engage a mating pin is disclosed. In various embodiments, the latch mechanism includes a latch frame; a latch arm pivotally mounted to the latch frame at a pivot axis; and a bias member configured to apply a load to the latch arm in a transverse direction generally perpendicular to the pivot axis and to bias the latch arm from rotating in a first rotational direction about the pivot axis and from rotating away from the mating pin.