Pressure Relief Assembly for Thrust Reverser Nacelle Burst Duct Protection

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Solution Overview

Problem

Modern aircraft turbofan propulsion systems face catastrophic failures due to rapid pressurization in nacelle compartments with high-pressure pneumatic ducts, which existing pressure relief mechanisms struggle to manage effectively, leading to structural integrity issues and potential deflections of thrust reverser structures.

Innovation Solution

A pressure relief assembly comprising a latch mechanism and a pressure relief door with a hinge mechanism, designed to automatically release radially outward in response to increased pressure, allowing pressurized fluid to vent to ambient air, and featuring a bracket weight less than the latch mechanism weight to enhance rapid pressure relief and provide visual indication of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure relief door is provided to limit pressure in the compartment, then pressure relief function is achieved, but the device complexity increases due to additional latch mechanisms and hinges

Engineering Contradiction:

Improvepressure relief functionVSAvoidlatch mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pressure relief latch mechanism is designed to automatically release in response to increased pressure without requiring external intervention. The system serves itself by using the pressure differential to trigger the release mechanism, eliminating the need for complex control systems or manual operation while maintaining reliable pressure relief functionality

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical control systems with a pressure-responsive mechanical latch that automatically releases when pressure thresholds are exceeded. This substitution simplifies the overall system by using direct pressure-mechanical coupling rather than requiring sensors, actuators, or control logic

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the pressure relief latch is designed to automatically release in response to increased pressure, then rapid pressure relief is achieved, but the structural strength requirements increase to handle the release forces

Engineering Contradiction:

Improvepressure relief speedVSAvoidstructural strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The latch mechanism is pre-configured with a release threshold that activates at predetermined pressure levels. The structural components are pre-designed to accommodate the expected release forces, and the hinge and bracket arrangements are established beforehand to distribute loads appropriately during automatic release

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The hinge mechanism and bracket support structure are designed to counterbalance the forces generated during latch release. The hinge provides a pivot point that redirects release forces, and the bracket arrangement distributes these forces to minimize stress on critical structural components

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Loss of information

If the bracket weight is made less than the latch mechanism weight, then the pressure relief door provides visual indication of use, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvevisual indication of useVSAvoidweight balance precision

Core Design Contradiction:

Loss of informationVSManufacturing precision

Solution Approach 1:

The pressure relief door utilizes visual indication through its positional change rather than color change. When the latch releases, the door moves to a different position that can be visually observed, providing information about pressure relief events without requiring painted surfaces or color-changing materials

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The system uses weight differential as a design parameter to create the visual indication function. By making the bracket lighter than the latch mechanism, the door naturally hangs down when released, creating a visible position change that indicates pressure relief has occurred

Inventive Principle:

Principle #35Parameter changes

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 effectively limits peak pressure and prevents structural damage by rapidly releasing pressure when thresholds are exceeded, ensuring the integrity of the thrust reverser structure and providing a visual indication of events during aircraft landing.

Implementation Method 1

The pressure relief latch may be configured to automatically release radially outward in response to an increase in pressure on the pressure relief door

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS11542027B2Pressure relief assembly

Publication Date: 2023.01.03 ROHR INC

AI summary

A thrust reverser of a nacelle may include a translating sleeve and an inner fixed structure a pressure relief assembly. A pressure relief mechanism may include a pressure relief door coupled via a hinge and a latch to the inner fixed structure. Alternatively, a pressure relief door may be coupled to a frame via a hinge and a latch to the inner fixed structure. The pressure relief assembly may limit deflections between the thrust reverser and the pylon in response to a burst duct. The pressure relief door may release from the latch automatically in response to an over pressurization event.