Stepping Motor Indexing for Foldable Aircraft Propeller Blades

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing propeller propulsion units for aircraft face challenges in efficiently deactivating propellers without affecting aerodynamic performance, particularly due to issues with precise angular positioning and drag reduction when blades are folded.

Innovation Solution

The use of a stepping electric motor coupled to the propeller hub allows for precise indexing and locking of the propeller in specific angular positions, enabling efficient deactivation and drag reduction by folding blades into housings within the nacelle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a friction brake is used to stop the propeller, then the propeller can be stopped at an angular position, but it cannot precisely index the propeller into an indexed angular position

Engineering Contradiction:

Improveangular positioning precisionVSAvoidbraking device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the friction brake mechanism with a stepping motor to achieve precise angular positioning. The stepping motor uses electromagnetic fields to rotate the propeller hub to exact angular positions without requiring mechanical friction-based braking, thereby achieving both precision and reduced complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from continuous friction-based stopping to discrete stepped angular positions. The stepping motor divides the rotation into precise incremental steps, allowing the propeller to be indexed to specific angular positions with high precision.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the propeller is stopped using a friction brake, then the blades can be folded, but additional energy is required to restart the propulsion motor

Engineering Contradiction:

Improveblade folding operationVSAvoidenergy consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The stepping motor serves dual functions: it acts as both the propulsion motor for driving the propeller and as the indexing mechanism for positioning the blades. This eliminates the need for a separate braking system and reduces overall energy consumption by using the same motor for multiple purposes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The stepping motor can reposition the propeller hub to the correct angular position without requiring external intervention or additional energy input beyond what is already used for propulsion. The motor self-corrects the angular position by delivering precise rotational steps.

Inventive Principle:

Principle #25Self-service

3Reliability

If the propeller is not precisely indexed, then the blades may contact structural elements during folding, but precise indexing requires complex positioning mechanisms

Engineering Contradiction:

Improvesafe blade foldingVSAvoidpositioning mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical positioning mechanisms with a stepping motor that uses electromagnetic control to achieve precise angular positioning. This substitution maintains reliability for safe blade folding while significantly reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from mechanical interlocking or cam-based positioning to electromagnetic angular positioning. The stepping motor controls the angular position parameter with high precision through electrical signals, simplifying the overall positioning mechanism while ensuring reliable blade folding.

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 solution enables precise control over propeller positioning, reducing drag and maintaining aerodynamic efficiency when propellers are deactivated, and allows for easy reactivation without the need for motor energy.

Implementation Method 1

a stepping electric motor which comprises a rotor which is coupled to the hub of the propeller

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS12208911B2Propulsion unit with foldable propeller blades and method for stopping the propeller in an indexed angular position

Publication Date: 2025.01.28 SAFRAN HELICOPTER ENGINES

AI summary

A propulsion unit having a propeller for an aircraft including a nacelle; a propeller mounted in the nacelle so as to be capable of rotating about a longitudinal axis of rotation, the propeller having blades mounted by a root so as to be capable of pivoting between a deployed position, in which they extend radially relative to the axis of rotation, and a folded position, in which they are longitudinally received against the nacelle; drive means that rotate the propeller; indexing means for stopping the propeller in at least one indexed angular position (θ i) relative to the nacelle; the propulsion unit wherein the indexing means consist of a stepping electric motor including a rotor that is coupled to the propeller.