Fabricated Intermediate Case with Strut-Mounted Engine Mounts

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Solution Overview

Problem

Existing intermediate cases of gas turbine engines, typically made by casting, are heavy, particularly for smaller engines, necessitating a lighter and more efficient design for improved support and mounting.

Innovation Solution

A fabricated engine case with an annular outer and inner case, circumferentially spaced struts, and a mount apparatus that includes a load-bearing member connecting the mount base to the struts rather than the outer case skin, providing additional stiffness and effective load distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an intermediate case is made by casting process, then manufacturing simplicity is improved, but weight increases

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidintermediate case weight

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The intermediate case is divided into multiple fabricated components (outer case, inner case, struts, mount base, load bearing members) that are manufactured separately and assembled together. This segmentation allows each component to be optimized for weight while maintaining structural integrity, resolving the contradiction between manufacturing simplicity and weight reduction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intermediate case employs a composite structure combining outer case, inner case, and strut components made through fabrication processes. This composite approach enables weight reduction compared to traditional casting while maintaining manufacturing feasibility through modular assembly of optimized components.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If mount base is directly attached to outer case skin, then structural simplicity is improved, but load bearing capability deteriorates

Engineering Contradiction:

Improvemounting structure simplicityVSAvoidload bearing capability

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

Load bearing members serve as intermediary elements between the mount base and the outer case structure. These members transmit and distribute mounting loads through the struts to the inner case, providing enhanced load bearing capability while maintaining relative structural simplicity through a clear load path.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mounting structure extends loads into the radial dimension through load bearing members that connect the mount base to struts, rather than relying solely on the outer case skin. This dimensional approach to load distribution enhances strength without significantly increasing overall structural complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Strength

If fabricated structure with struts is used, then structural stiffness is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural stiffnessVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The structure is segmented into outer case, inner case, and strut components that can be manufactured using standard fabrication processes. This segmentation maintains manufacturing complexity at acceptable levels while achieving superior structural stiffness through the rigid strut connections between cases.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple fabricated components (outer case, inner case, struts, mount base) are merged into an integrated assembly that achieves high structural stiffness. The combining of these components creates a rigid structure that outperforms traditional casting while keeping individual component manufacturing relatively simple.

Inventive Principle:

Principle #5Merging (Combining)

4Strength

If load bearing member extends through gap, then load distribution is improved, but assembly precision requirements increase

Engineering Contradiction:

Improveload distributionVSAvoidassembly precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The load bearing member acts as an intermediary that spans the gap between the mount base and outer case skin, distributing loads effectively. This intermediary element provides a defined attachment point that can accommodate reasonable assembly tolerances while maintaining superior load distribution characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8801376B2Fabricated intermediate case with engine mounts

Publication Date: 2014.08.12 PRATT & WHITNEY CANADA CORP

AI summary

A fabricated engine case has a plurality of circumferentially spaced struts radially extending between an outer case and an inner case. A mount apparatus is affixed to the outer case of the engine case. The mount apparatus is a mount base radially spaced apart from a circumferential skin of the outer case and a load bearing member extending radially inwardly to connect the mount base to an outer end of one of the struts.