Escape Hatch Handle Assembly With Two-Stage Cam Unlocking

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Solution Overview

Problem

Existing aircraft escape hatches face challenges in maintaining an open position during emergency egress due to wind gusts or other loads, and the handle assemblies require complex sequential actuation to unlock multiple locking systems, complicating efficient passenger egress.

Innovation Solution

The escape hatch stay system includes a first and second stop arm that over-center to lock the hatch open, with a gas strut damping excessive loads, and a handle assembly that unlocks both locking systems with a single rotational input using a cam mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex sequential actuation mechanism is used to unlock multiple locking systems, then the escape hatch can be securely locked, but the operation complexity increases and egress efficiency decreases

Engineering Contradiction:

Improvelocking securityVSAvoidhandle operation complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent combines multiple locking systems into a single integrated locking mechanism. The handle assembly operates one cam mechanism that simultaneously controls both locking systems through a shared shaft and cam profile, eliminating the need for separate sequential actuation of multiple locks.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single cam mechanism serves multiple functions by unlocking both locking systems through its rotation. The cam profile is designed to interact with both locking mechanisms simultaneously, allowing one handle operation to perform the work of multiple separate locking releases.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple locking systems are used on the escape hatch, then the security and reliability improve, but the device complexity and operation time increase

Engineering Contradiction:

Improveescape hatch securityVSAvoidlocking system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple locking control functions into a single cam mechanism. Instead of having separate actuators for each lock, one cam with a specifically designed profile controls both locking systems through a shared shaft, reducing the number of independent components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cam mechanism is segmented into different profile sections (concave and convex portions) that correspond to different locking systems. Each segment of the cam profile engages with a specific locking mechanism at different rotational positions, allowing sequential unlocking through a single rotation.

Inventive Principle:

Principle #1Segmentation

3Productivity

If the escape hatch is designed to remain open against external forces like wind gusts, then the egress efficiency improves, but the structural stability and control become challenging

Engineering Contradiction:

Improveegress efficiencyVSAvoidhatch position control

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent employs a stay system with stop arms that act as mechanical counterweights to balance the escape hatch. The stop arms are positioned to provide counterbalancing force against the hatch weight and external forces like wind gusts, allowing the hatch to remain stable in the open position without requiring continuous active control.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The stay system is pre-configured with stop arms that engage beforehand to prevent the hatch from swinging too far or closing unintentionally. The mechanical linkage is designed to automatically engage the stop arms at appropriate positions, providing prior cushioning against excessive movement or unintended closure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 system ensures the escape hatch remains open against external forces, preventing damage and allows efficient egress by simplifying the handle operation with a single-hand, two-stage rotation to unlock both locking mechanisms.

Implementation Method 1

an output arm configured to dampen an applied load

Methodology Applied

Scientific EffectDamping: Damping

Implementation Method 2

a cam mechanism that transforms rotational motion into linear displacement

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentUS12428870B2Handle assembly for escape hatch

Publication Date: 2025.09.30 TEXTRON INNOVATIONS INC

AI summary

A handle assembly for an escape hatch. A handle assembly for an escape hatch comprises an interior handle and an exterior handle. The interior handle has an interior cam associated therewith and the exterior handle has an exterior cam associated therewith. The interior cam and the exterior cam each have a concave profile surface and a curved profile surface. A middle cam is sandwiched between the interior cam and the exterior cam and has a notched profile. The interior and exterior cams are associated with a tumbler having a flag. The middle cam is associated with an output rod operatively coupled to a second flag. Each of the interior handle and the exterior handle can be successively rotated in a first arc of rotation and a second arc of rotation with one hand. The first and second arcs of rotation are respectively associated with the flag and the second flag.