Overhead Safety Hook Latch With Visible Open-State Cover

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Solution Overview

Problem

Existing aircraft latches are heavy, complex, and prone to accidental opening or damage due to weight distribution issues and lack of safety measures, which can lead to structural damage and unnoticed open latches.

Innovation Solution

A latch mechanism with a center of gravity positioned in front of the mounting pin, a nested toggle linkage, and a handle cover to prevent accidental opening, along with a keeper detector to ensure proper closure, providing a compact, lightweight design with enhanced visibility and safety features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If prior art latches are designed with complex quality components to ensure secure closure, then the latch reliability is improved, but the latch size and weight increase

Engineering Contradiction:
Improvelatch closure securityVSAvoidlatch weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The latch mechanism is divided into distinct functional segments: a mounting pin portion, a latch arm with hook, and a toggle linkage system. This segmentation allows each component to be optimized independently for strength and weight, reducing overall latch weight while maintaining closure security through the distributed functional architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The toggle linkage is nested within the latch arm structure, with the linkage pivots integrated into the latch arm body. This nesting eliminates separate mounting structures and reduces the overall latch envelope, decreasing weight while maintaining the mechanical advantage needed for secure closure.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If the center of gravity of the latch is positioned behind the mounting pin to allow gravity to bias the latch closed, then the latch automatically closes, but the hook may obstruct the panel opening and cause damage when the panel is closed

Engineering Contradiction:
Improveautomatic latch closureVSAvoidpanel damage from hook obstruction
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The center of gravity is inverted to the opposite side of the mounting pin, positioned forward of the pin rather than behind it. This inversion changes the gravitational bias from closed-position to open-position, requiring the latch to be deliberately closed by the user while preventing the hook from obstructing the panel opening during closure.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The toggle linkage acts as an intermediary mechanism between the latch arm and the hook. It provides mechanical control over the hook's position, allowing the latch to be closed deliberately through toggle engagement while preventing accidental hook obstruction of the panel opening during the closing motion.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If dead weight is added to the hook end of the latch to prevent obstruction of the opening, then the hook hangs downward away from the opening, but the overall latch weight increases

Engineering Contradiction:
Improvepanel damage preventionVSAvoidlatch weight
Core Design Contradiction:
Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The function of providing downward bias to prevent hook obstruction is extracted from the hook end itself and relocated to the center of gravity positioning forward of the mounting pin. This extraction eliminates the need for additional dead weight at the hook end, preventing panel obstruction while maintaining overall latch weight reduction.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If a push-in trigger actuated release mechanism is used for ease of use, then the latch is easy to operate, but accidental contact with the trigger can open the latch

Engineering Contradiction:
Improvelatch release easeVSAvoidaccidental latch opening
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The trigger mechanism is designed with preliminary protective features: the trigger is recessed within the latch body and requires a deliberate pushing motion to activate. This preliminary anti-action design prevents accidental activation by objects or inadvertent contact while maintaining ease of operation through the simple push-in release mechanism.

Inventive Principle:
Principle #9Preliminary anti-action

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 the risk of latch-related damage and accidental opening, ensuring secure closure and easy detection of open latches, while maintaining a reduced size and weight, thus protecting aircraft structures and enhancing maintenance visibility.

Implementation Method 1

places the center of gravity of the mechanism in front of the mounting pin. Therefore, 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

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

A spring is contained within the latch body and applies force to bias the trigger in the engaged position

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3513022B1Safety hook latch
Publication Date: 2026.01.14 QRP INC
  • EP3513022B1 patent drawingFigure 1~2
  • EP3513022B1 patent drawingFigure 3
  • EP3513022B1 patent drawingFigure 4

AI summary

A latch for releasably connecting two elements is operable between engaged and released positions. An elongate handle opens and closes a latch mechanism about a first axis of rotation at the rear end of the handle. The latch handle is held closed only when the latch mechanism is in the engaged position and is lockable in the closed position by a manually operable handle catch. The front end of a handle cover is rotatably connected to the front end of the handle. The cover has a cover catch on the rear end, which is engagable with the latch mechanism to hold the cover closed. The cover is substantially coextensive with and in abutment with the handle. When the latch is mounted overhead and is open, the handle extends downward by the force of gravity and the cover extends downward away from the handle. In this configuration, the open latch is highly visible.