Composite Aircraft Gearbox Casing with Internal Liner

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Solution Overview

Problem

The existing upper casings for gearboxes in aircraft are heavy due to their metal composition, which complicates the use of composite materials for weight reduction while maintaining structural integrity and equipment support.

Innovation Solution

A composite upper casing design comprising a hollow shell made of composite materials with a simple geometrical shape, combined with an internal liner for equipment support, allowing for the use of preimpregnated fibers and resin transfer molding for fabrication, and metal reinforcement for structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the upper casing is made of metal to transmit forces and moments and carry equipment, then the structural integrity and equipment support are ensured, but the weight of the casing increases significantly

Engineering Contradiction:

Improvestructural integrityVSAvoidcasing weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The upper casing is divided into two distinct parts: an external shell made of composite material and an internal liner made of metal. The composite shell transmits forces and moments while the metal liner provides equipment support, allowing each material to be optimized for its specific function and reducing overall weight compared to a solid metal construction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The upper casing uses a composite structure combining composite material (for the shell) and metal material (for the liner). This composite approach allows the casing to achieve both weight reduction through composite material and sufficient strength through the metal liner, resolving the contradiction between weight and structural integrity

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If the upper casing is made of composite materials to reduce weight, then the casing weight is reduced, but the ability to transmit forces and moments and support equipment is compromised

Engineering Contradiction:

Improvecasing weightVSAvoidforce transmission capability

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The upper casing is segmented into a composite shell for weight reduction and a metal liner for strength. The composite shell maintains reduced weight while the integrated metal liner ensures adequate force transmission capability, allowing the system to achieve both goals simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The composite construction combines lightweight composite material with metal reinforcement in the form of a liner. This allows the casing to achieve weight reduction from the composite material while maintaining force transmission capability through the metal liner, resolving the contradiction between weight and strength

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If the upper casing carries various pieces of equipment with projections, then the equipment support functionality is achieved, but the geometrical shape becomes complex and manufacturing difficulty increases

Engineering Contradiction:

Improveequipment support functionalityVSAvoidmanufacturing simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The upper casing is segmented into a simple composite shell and a separate metal liner. The liner can be designed with the necessary geometrical complexity to support equipment, while the composite shell maintains a simple shape for easier manufacturing. This segmentation allows equipment support functionality to be achieved without compromising manufacturing simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The metal liner provides localized geometrical complexity and equipment support functionality only where needed, while the majority of the upper casing shell maintains a simple geometrical shape suitable for composite manufacturing. This local quality approach ensures equipment support functionality without requiring the entire structure to be complex

Inventive Principle:

Principle #3Local quality

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 achieves a reduced weight gearbox casing that maintains performance in transmitting forces and moments while supporting equipment, simplifying the manufacturing process and reducing material complexity.

Implementation Method 1

allowing for the use of preimpregnated fibers and resin transfer molding for fabrication

Methodology Applied

Scientific EffectResin transfer molding:

Data Source

PatentUS10737777B2Gearbox casing, a gearbox, and an aircraft

Publication Date: 2020.08.11 EUROCOPTER FRANCE SA

AI summary

An upper casing with a hollow shell made of composite materials. The shell was a side wall that extends in elevation from a housing flange to a housing collar, the side wall including at least one cutout. The upper casing includes an internal liner that is inserted inside the shell and that is fastened to an inside face of the shell, the liner comprising a base and a top, together with at least two legs extending in elevation from the base to the top, the liner further comprising at least one equipment support in register with a cutout, each equipment support being for carrying a removable piece of equipment of the upper casing.