Nested Toggle Latch with Forward Center of Gravity
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Solution Overview
Problem
Aircraft latches are typically large and heavy, which contradicts the need for lightweight components, and their design can lead to accidental damage to aircraft panels due to weight distribution issues, where the latch's hook may obstruct panel closure.
Innovation Solution
A latch mechanism with the center of gravity positioned in front of the mounting pin, featuring a nested toggle linkage with U-shaped links that fold together to minimize size and weight, and a keeper detector to prevent accidental closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional aircraft latches are used with mounting pin at the rear, then the latch provides sufficient leverage and reach, but the hook end points upward and may obstruct panel closure causing damage
Solution Approach 1:
The patent inverts the traditional latch design by positioning the mounting pin at the forward end of the latch arm rather than at the rear. This inversion changes the weight distribution so the center of gravity is forward of the pivot point, causing the hook to hang downward away from the panel during opening, eliminating the obstruction problem while maintaining leverage through the toggle linkage mechanism
2Reliability
If dead weight is added to the hook end to prevent obstruction, then the latch hangs downward safely, but the overall weight increases contradicting aircraft weight reduction goals
Solution Approach 1:
The patent extracts the unnecessary dead weight from the hook end by redesigning the latch with the mounting pin positioned at the forward end. This design change naturally positions the center of gravity forward of the pivot point, allowing the latch to hang downward in the safe position without requiring additional weight, thus eliminating the contradiction between safety and weight reduction
3Weight of moving object
If the latch is designed to be lightweight with thin aircraft panels, then weight is reduced, but the structure becomes delicate and prone to damage from latch obstruction
Solution Approach 1:
By inverting the latch design with the mounting pin at the forward end, the patent achieves both lightweight construction and structural safety. The inverted configuration ensures the hook hangs downward away from thin, delicate panels during opening, preventing damage while maintaining the lightweight design necessary for modern aircraft
4Volume of moving object
If the mounting pin slot is positioned at the end of the latch arm, then the kinematic envelope is minimized, but the latch reach is reduced
Solution Approach 1:
The patent employs a nested toggle linkage mechanism where the toggle links fold concentrically around the latch arm. This nesting allows the latch to achieve sufficient reach and leverage while minimizing the overall kinematic envelope and volume, as the toggle mechanism collapses into a compact configuration when not in use
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 provides a lightweight latch with reduced kinematic envelope, preventing damage to aircraft structures by ensuring the hook hangs away from the keeper, allowing adequate reach and leverage while maintaining structural protection.
Implementation Method 1
the linkage-to-hook pivot joint is on the body of the latch arm in front of the mounting pin... providing adequate reach and leverage
Implementation Method 2
in applications where the latch swings in the vertical plane, the hook will necessarily hang downward away from the keeper when the latch is opened... center of gravity of the latch is 'behind' (in the direction away from the hook) the pivot point
Data Source
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AI summary
A latch with a unique nesting toggle linkage that extends and retracts a hook via movement of an actuation an actuation handle. The linkage links have U-shaped lateral cross sections with a central channel into which the respective links nest when the latch is closed to minimize the overall volume of the latch. The links fold toward each other while closing which reduces its overall length when fully closed. The components of the latch are arranged so that the center of gravity of the latch is positioned in front of a mounting pin. Therefore, in applications where the latch swings in the vertical plane, the hook will necessarily hang downwardly away from the keeper when the latch is open. A keeper detector prevents the actuation handle from closing if the keeper has not been first captured in the mouth of the hook.