Alternator Shaft Coupling for Turbine Inspection Drive

Solution Overview

Problem

The existing mechanical drive systems for airplane engine high pressure sub assemblies are bulky and heavy due to the need for stepdown gearing to facilitate slow turning during endoscopic inspections, which increases the specific consumption of the engine and restricts access.

Innovation Solution

Combining the shaft lines of the gearbox and alternator, allowing the high pressure sub assembly to be driven via the alternator's rotor and shaft, with accessible coupling elements for external actuators, thereby simplifying the gearbox and reducing the need for stepdown gearing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If stepdown gearing is added to the gearbox to enable slow turning of the high pressure sub assembly during inspection, then the ease of operation is improved, but the weight and volume of the gearbox increase

Engineering Contradiction:

Improveease of turning high pressure sub assemblyVSAvoidweight of gearbox

Core Design Contradiction:

Ease of operationVSWeight of stationary object

Solution Approach 1:

The alternator shaft line, originally designed solely to drive the alternator for FADEC power supply, is made multi-functional by adding a coupling element that enables it to also serve as the drive interface for manual inspection operations. This eliminates the need for a separate dedicated stepdown gearing system while providing both functions through a single shaft line.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If stepdown gearing is added to the gearbox to enable slow turning of the high pressure sub assembly during inspection, then the ease of operation is improved, but the volume of the gearbox increases

Engineering Contradiction:

Improveease of turning high pressure sub assemblyVSAvoidvolume of gearbox

Core Design Contradiction:

Ease of operationVSVolume of stationary object

Solution Approach 1:

The alternator shaft line, originally designed solely to drive the alternator for FADEC power supply, is made multi-functional by adding a coupling element that enables it to also serve as the drive interface for manual inspection operations. This eliminates the need for a separate dedicated stepdown gearing system while providing both functions through a single shaft line.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If dedicated stepdown gearing is added for inspection operations, then the ease of operation is improved, but the device complexity increases

Engineering Contradiction:

Improveease of turning high pressure sub assemblyVSAvoidcomplexity of gearbox

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The alternator shaft line, originally designed solely to drive the alternator for FADEC power supply, is made multi-functional by adding a coupling element that enables it to also serve as the drive interface for manual inspection operations. This eliminates the need for a separate dedicated stepdown gearing system while providing both functions through a single shaft line.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9027355B2Mechanical drive device for driving the high pressure sub assembly of an airplane engine

Publication Date: 2015.05.12 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A manual mechanical drive to a high pressure sub assembly of a turbojet during endoscopic inspection of the high pressure turbine is provided. A coupling element suitable for coupling with an external actuator such as a crank handle is fitted on the axis of an alternator that is normally driven mechanically via the high pressure sub assembly, thereby providing a coupling suitable for driving said high pressure sub assembly.