Variable Pitch Fan Module Reducing Hub Ratio

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing fan modules with variable pitch blades for propulsion assemblies face challenges in reducing radial bulk and hub ratio while avoiding significant structural modifications, with conventional timing change systems being cumbersome and extending the rotor shaft length, leading to increased drag and operational constraints.

Innovation Solution

A fan module design featuring a rotor with a pitch change system incorporating a speed reducer with an epicyclic gear, a fixed planet carrier, and internal bearings, which reduces axial and radial dimensions by integrating the control means radially inside the rotor shaft, eliminating the need for an oil transfer bearing and minimizing hub ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional pitch change system with an annular ferrule attached to the rotor shaft is used, then the control means can be positioned to adjust blade pitch, but the radial space is increased and the hub ratio is increased

Engineering Contradiction:

Improveblade pitch adjustment capabilityVSAvoidradial space occupied by pitch change system

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The control means is nested within the rotor shaft structure itself, with the fixed body mounted on the inner circumference of the rotor shaft and the movable body positioned inside the rotor shaft. This nesting arrangement allows the pitch change system to be integrated within the existing rotor shaft volume, eliminating the need for an external annular ferrule and reducing the overall radial space occupied by the pitch change system.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention repositions the control means from a radial arrangement (external annular ferrule) to an axial arrangement (inside the rotor shaft). By utilizing the axial dimension of the rotor shaft for housing the control means, the system achieves blade pitch adjustment capability while minimizing radial space occupation and reducing the hub ratio.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If an annular ferrule attached to the rotor shaft is used for the pitch change system, then the control means can be positioned, but the length of the rotor shaft is increased

Engineering Contradiction:

Improveblade pitch adjustment capabilityVSAvoidrotor shaft length

Core Design Contradiction:

Ease of operationVSLength of moving object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

3Ease of operation

If the pitch change system is installed in an annular space formed between the rotor shaft and an annular ferrule, then the control means can be positioned, but the radial annular space available under the pivot axis is reduced

Engineering Contradiction:

Improveblade pitch adjustment capabilityVSAvoidradial annular space under pivot axis

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

Instead of positioning the control means externally on the rotor shaft (conventional approach), the invention inverts the arrangement by positioning the control means internally within the rotor shaft structure. The fixed body is mounted on the inner circumference while the movable body is positioned inside the rotor shaft, effectively inverting the traditional radial arrangement to an axial arrangement that preserves radial annular space.

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration reduces the radial bulk and hub ratio, enhances operational efficiency by minimizing drag, and eliminates potential leaks and unbalance issues associated with oil transfer systems, allowing for more compact and efficient integration within aircraft propulsion systems.

Implementation Method 1

a power shaft driving the rotor shaft via an epicyclic gear reducer, the gear reducer comprising a planetary gear connected to the power shaft and a planet carrier

Methodology Applied

Scientific EffectEpicyclic gearing: Epicyclic Gearing

Implementation Method 2

at least one internal bearing arranged between the fixed annular shroud of the planet carrier and the rotor shaft of the fan, and a first and a second bearing being mounted between a support ring secured to the fixed casing and the rotor shaft of the fan

Methodology Applied

Scientific EffectBall bearing: Ball Bearing

Data Source

PatentEP3647546B1Fan module with blades with variable pitch angle

Publication Date: 2024.11.27 SAFRAN AIRCRAFT ENGINES SAS

Figure 1~2
Figure 3

AI summary

The invention relates to a blower module (1) with variable pitch blades (16) for a longitudinal axis propulsion assembly, said module (1) comprising: - a rotor (13) through which a rotor shaft (10) passes along the longitudinal axis X and carrying the blades (16) of the blower (2), - a blade pitch change system (22) comprising connecting means (34) linked to the blades (16) of the blower (2) and a control means (23) acting on the connecting means (34), the control means (23) comprising a fixed body (35) and a movable body (36) in translation along the longitudinal axis X relative to said fixed body (35), and - a load transfer bearing (28) arranged between the connecting means (34) and the control means (23).According to the invention, the blower module (1) comprises a power shaft (30) driving the rotor shaft (10) via an epicyclic gear reducer (50), the gear reducer (50) comprising a planetary gear (51) connected to the power shaft (30) and a planet carrier (53) comprising a fixed annular ferrule (56) integral with a fixed housing (9), the fixed body (35) of the control means (23) being mounted on said annular ferrule.