In-Line Isolator for Aircraft APU Strut Mounting

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Solution Overview

Problem

Existing isolator systems for aircraft auxiliary power units are prone to being larger and heavier due to complex loading requirements, which makes them more susceptible to deterioration and damage, and when one isolator fails, it can transmit undesirable vibrations through multiple struts, affecting both the power unit and the fuselage.

Innovation Solution

The isolator is designed for in-line mounting with a support strut, featuring an elastomer member maintained in a compression/shear state, which allows for a simpler, lighter-weight design that can be mounted away from the power unit, ensuring that if it fails, the impact is limited to a single strut, and includes a fail-safe configuration to prevent escape of the wedge and rod components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If isolators are mounted directly to the power unit with struts pivotably connected, then isolation and support from multiple directions is achieved, but the isolator size and weight increase

Engineering Contradiction:

Improveisolation capability from multiple directionsVSAvoidisolator weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The isolator system is divided into separate components: the isolator body and the struts are disconnected. The isolator is mounted away from the power unit, and struts connect the isolator to the power unit, allowing each component to be optimized independently for weight and function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The isolator serves as an intermediary element positioned between the power unit and the aircraft structure, but physically separated from direct mounting to the power unit. This intermediary positioning allows the isolator to handle loads more efficiently with reduced weight while still providing multi-directional isolation through the strut connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If isolators are mounted directly to the power unit, then vibration isolation is effective, but susceptibility to deterioration and damage increases

Engineering Contradiction:

Improvevibration isolation effectivenessVSAvoidsusceptibility to deterioration and damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The isolator is extracted from its traditional mounting position directly on the power unit and relocated to a separate position. This separation removes the isolator from the harsh thermal and mechanical environment near the power unit, reducing its susceptibility to deterioration while maintaining vibration isolation effectiveness through the strut linkage.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If a single isolator is connected to multiple struts, then vibration isolation is provided, but failure of the isolator transmits vibrations through multiple struts

Engineering Contradiction:

Improvevibration isolationVSAvoidvibration transmission upon failure

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system incorporates a fail-safe configuration with a retention structure that anticipates potential isolator failure. This preventive design ensures that if the isolator fails, the wedge and rod components are retained and cannot escape to transmit harmful vibrations through the struts, thus cushioning against the harmful effects of failure before they can propagate.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Weight of stationary object

If isolator is designed for in-line mounting with simpler configuration, then weight and complexity are reduced, but mounting away from power unit must maintain isolation effectiveness

Engineering Contradiction:

Improveisolator system weightVSAvoidvibration isolation effectiveness

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

The isolator is positioned in a different spatial dimension away from the power unit, mounted on the aircraft structure rather than directly on the power unit. This dimensional repositioning, combined with the strut linkage, maintains the isolation functionality while allowing for a lighter, simpler isolator design that doesn't need to directly bear the power unit's weight and vibrations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This design reduces the weight and susceptibility to damage of the isolator system while ensuring that vibratory forces are isolated effectively, minimizing the transmission of vibrations and maintaining structural integrity even if an isolator fails.

Implementation Method 1

an elastomer member configured to be substantially permanently maintained in a compression/shear state

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

Isolators have been used to minimize the transmission of shock and vibrations between objects

Methodology Applied

Scientific EffectDamping: Damping

Data Source

PatentEP2462363B1Isolator useful for in-line mounting with a strut

Publication Date: 2014.06.25 ITT MANUFACTURING ENTERPRISES LLC

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AI summary

A system for limiting the exchange of shock and vibration motions and forces between a load and its supporting structure including an isolator. In one aspect, the isolator is designed for in-line mounting with a support strut. The isolator includes an elastomer member that may be substantially permanently maintained in a compression/shear state.