Aircraft Engine Mount Layout for Decoupled Torque Roll Vibration

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Solution Overview

Problem

There is a compromise in designing aircraft engine mounting arrangements that requires high stiffness to limit engine deflection under gravity loads while also needing low stiffness to minimize torque and vibration transmission, which existing designs struggle to balance effectively.

Innovation Solution

The use of a mounting arrangement featuring one-degree-of-freedom links and A-frame links with varying stiffness configurations, where the roll constraint has a lower stiffness than the axial and link stiffness, decouples torque roll mode from other degrees of freedom, allowing for low vibratory force transmission while maintaining low deflections under high g loading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If high mount stiffness is used, then engine deflection is limited under gravity loads, but torque and vibration transmission increases

Engineering Contradiction:

Improveengine deflectionVSAvoidtorque and vibration transmission

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The engine mounting system is segmented into multiple independent links (forward links, rearward links, A-frame links, axial constraint, roll constraint) each with specific stiffness characteristics. This segmentation allows different parts of the mounting system to have different stiffness values, enabling the system to simultaneously limit engine deflection while isolating torque vibrations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different mounting links are assigned different stiffness qualities based on their functional requirements. The forward and rearward links have high stiffness to limit deflection, while the roll constraint has low stiffness to isolate torque vibrations. This local differentiation of stiffness properties resolves the contradiction between deflection limitation and vibration isolation.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If low mount stiffness is used, then torque and vibration transmission is reduced, but engine deflection increases under gravity loads

Engineering Contradiction:

Improvetorque and vibration transmissionVSAvoidengine deflection

Core Design Contradiction:

Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The mounting system is divided into multiple functional segments with different stiffness characteristics. High-stiffness links (forward, rearward, axial constraints) handle deflection limitation, while low-stiffness elements (roll constraint) handle vibration isolation, allowing both requirements to be met simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Specific mounting elements are assigned local stiffness qualities matching their functional needs. The roll constraint has low stiffness locally to reduce torque transmission, while other links maintain high stiffness locally to prevent excessive deflection, resolving the global contradiction through local property differentiation.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11214377B2Mount arrangement for torque roll vibration isolation

Publication Date: 2022.01.04 PRATT & WHITNEY CANADA CORP

AI summary

A mounting arrangement for mounting a rotary engine to an aircraft structure, wherein the engine has a three orthogonal axes comprising: a roll axis; a pitch axis; and a yaw axis. The mounting arrangement comprises: one-degree-of-freedom links with reaction axes passing through the roll axis. A separate roll constraint has a moment reaction about the roll axis to decouple the torque roll mode from the other one-degree-of-freedom links.