Outer Sun Gear Crown Mounting for Precise Torque-Based Centering

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Solution Overview

Problem

In turbomachine reduction gears, particularly with herringbone toothings, precise positioning and orientation of outer sun gear crowns are challenging due to machining defects, leading to load asymmetry, premature wear, efficiency degradation, noise, and vibration, and existing methods require assembled grinding and paired crowns, limiting interchangeability and repair simplicity.

Innovation Solution

A method involving the independent centring and orientation of first and second crowns using identical torques applied in the same direction around their axes, eliminating the need for assembled grinding, allowing for interchangeable crowns and simplified repair by applying torques corresponding to operational phases, and optionally joining the crowns using annular flanges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional methods (pins, screws, assembled grinding) are used to centre and orient the first and second crowns, then the crowns can be positioned and oriented in relation to each other, but the process becomes complex, time-consuming, and limits interchangeability

Engineering Contradiction:

Improvepositioning and orientation precision of crownsVSAvoidcomplexity of centring and orientation process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies torques to the first and second crowns to modify their positioning parameters. By applying identical torques in the same direction to both crowns, the method achieves precise positioning and orientation while maintaining simplicity and interchangeability, avoiding complex mechanical centring devices

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts the complex mechanical centring and orientation devices (pins, screws, assembled grinding processes) from the system and replaces them with a simpler torque application method. This removes the disturbing complexity while maintaining the required positioning precision

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If traditional methods with pins and screws are used to fix the crowns, then the crowns can be held in position, but the ease of repair is reduced and individual crown replacement becomes difficult

Engineering Contradiction:

Improvestability of crown positioningVSAvoidsimplicity of crown replacement

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent treats the first and second crowns as independent, interchangeable segments. By applying torques independently to each crown and allowing them to be replaced individually while maintaining positioning stability, the method enables easier repair and maintenance without requiring replacement of the entire crown assembly

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If machining defects are present, then the axial positions of intercepts vary, but using traditional centring methods increases load asymmetry and premature wear

Engineering Contradiction:

Improvealignment of axial positions in radial planeVSAvoidload distribution symmetry and wear resistance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses torque application to dynamically adjust the positioning parameters of the crowns, compensating for machining defects. By applying identical torques to both crowns, the method ensures that axial positions of intercepts align in the same radial plane while maintaining load symmetry and preventing premature wear

Inventive Principle:

Principle #35Parameter changes

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 method ensures better contact distribution between planet gear toothings and crowns, reduces scrap, facilitates assembly, increases service life, and simplifies repairs by allowing individual crown replacement, while maintaining proper positioning and orientation without the need for assembled grinding.

Implementation Method 1

a first torque-applying means for applying a first torque to the first crown centred on an axis of the first crown and a second torque-applying means for applying a second torque to the second crown centred on an axis of the second crown, the first torque and the second torque having identical values and being applied in a same direction of rotation about the axes of the first and second crowns

Methodology Applied

Scientific EffectTorque: Torque

Data Source

PatentUS11499623B2Installation for mounting an outer sun gear

Publication Date: 2022.11.15 SAFRAN TRANSMISSION SYST

AI summary

An installation for mounting an outer sun gear in a reduction gear. The reduction gear includes an outer sun gear and planet gears meshing with an inner sun gear and with the outer sun gear and each mounted for free rotation around a pivot of a planet carrier. The outer sun gear includes a first crown having a first toothing and a second crown having a second toothing each meshing with first and second toothings of the planet gears. The installation includes a frame for supporting the reduction gear along its longitudinal axis, and first and second torque applicators, such as cylinders, that apply a torque around an axis of first and second rings, respectively. The first ring is configured to engage with the first crown of the outer sun gear and the second ring is configured to engage with a second crown of the outer sun gear.