Generator Driven Gear Tooth Profile for Stable Output Frequency

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Solution Overview

Problem

Integrated drive generators in aircraft face challenges in maintaining a constant frequency of electric power generation due to varying input shaft speeds from gas turbine engines, which affects the speed and frequency of the generator driven gear.

Innovation Solution

The implementation of a replacement generator driven gear with a specific gear tooth profile, characterized by unique roll angles at points A, B, C, and D, and a method for replacing the existing generator driven gear within an integrated drive generator system, ensuring a consistent speed and frequency output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional generator driven gear is used with varying input shaft speeds, then the generator can operate with flexible speed input, but the output frequency becomes variable and unacceptable

Engineering Contradiction:
Improveinput speed flexibilityVSAvoidoutput frequency consistency
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by modifying the gear tooth profile geometry, specifically the roll angles at different points (A, B, C, D) along the tooth profile. This geometric parameter modification allows the gear to maintain a constant output frequency despite variations in input shaft speed, resolving the contradiction between input flexibility and output consistency.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the gear tooth profile is modified with specific roll angles, then the output frequency consistency is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveoutput frequency consistencyVSAvoidgear tooth profile manufacturing
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent defines specific parameter ranges for roll angles at different gear tooth profile points (A: 14.2-15.7°, B: 16.2-17.7°, C: 22.3-23.8°, D: 24.3-25.8°). These controlled parameter specifications enable consistent performance while providing clear manufacturing targets, balancing precision requirements with manufacturability.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3508758B1Generator driven gear for integrated drive generator
Publication Date: 2024.07.24 HAMILTON SUNDSTRAND CORP
  • EP3508758B1 patent drawingFigure 1
  • EP3508758B1 patent drawingFigure 2A~2C

AI summary

A generator driven gear for use in an integrated drive generator has a gear body extending between a first end and a second end and having a disc extending radially outwardly. A boss extends from the disc toward the second end. There are outer gear teeth outwardly of an outer diameter of the disc. The outer gear teeth having a unique gear tooth profile with roll angles A, B, C, and D. An integrated drive generator and a method are also disclosed.