Electric Propeller Blade Pitch Actuation Without Hydraulics

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Solution Overview

Problem

Existing aircraft propeller systems face inefficiencies and weight challenges due to hydraulically-powered pitch change mechanisms, which require high pressure oil flow and heavy motors, limiting their performance and efficiency.

Innovation Solution

A propeller blade pitch change system utilizing a pitch change actuator, such as a closed loop servomotor or stepper motor, connected via a harmonic or planetary gear train, located in the blade pocket with anti-rotation features, allowing for individual control of each propeller blade's pitch angle, detected by sensors and controlled by a pitch change controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If hydraulically-powered pitch change mechanisms are used, then pitch change capability is achieved, but system weight increases and efficiency decreases

Engineering Contradiction:

Improvepitch change capabilityVSAvoidsystem weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent replaces the hydraulic power system with an electric power system. Specifically, electric motors (such as servomotors or stepper motors) are used instead of hydraulic pumps and actuators to drive the pitch change mechanism. This substitution eliminates the need for hydraulic fluid, high-pressure oil lines, and associated valves, thereby reducing system weight while maintaining pitch change capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the hydraulic system components from the propeller assembly. By eliminating the hydraulic pump, reservoir, fluid lines, and hydraulic actuators, the design reduces overall system weight and complexity while achieving the same functional outcome through electric motors and gear mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

2Power

If centrally located motor driving central pitch change mechanisms is used, then pitch change is achieved, but device complexity and weight increase

Engineering Contradiction:

Improvepitch change capabilityVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent divides the pitch change mechanism into distributed components located at individual blade roots rather than a single central mechanism. Each blade has its own pitch change actuator (electric motor) and gear train, allowing independent control of each blade's pitch angle. This segmentation simplifies the overall system architecture by eliminating complex central传动 mechanisms and high-pressure hydraulic distribution systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements local pitch control by placing individual pitch change actuators at each blade root. This allows each blade to have its pitch angle independently adjusted based on local aerodynamic conditions, improving overall propeller efficiency while simplifying the control system compared to a centralized mechanical linkage system.

Inventive Principle:

Principle #3Local quality

3Force

If hydraulic systems are used, then pitch change force is sufficient, but system weight and size increase

Engineering Contradiction:

Improvepitch change forceVSAvoidsystem weight

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The patent substitutes electric motors with sufficient torque capability for hydraulic actuators. The electric motors are coupled with gear trains (such as planetary gears or harmonic drives) that provide mechanical advantage, delivering the necessary pitch change force while keeping the motor size and weight manageable. This electric-gear system replaces the heavier hydraulic pump, fluid lines, and high-pressure actuators.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables compact, efficient, and precise control of propeller blade pitch, improving aerodynamic balance and reducing weight by eliminating the need for heavy hydraulic systems, allowing for faster pitch changes and higher torque outputs.

Implementation Method 1

The pitch change actuator is one of a closed loop servomotor or a stepper motor

Methodology Applied

Scientific EffectServomotor/Stepper motor: Linear Motor

Implementation Method 2

the drive mechanism is one of a harmonic gear train or a planetary gear train

Methodology Applied

Scientific EffectGear train: Gear

Data Source

PatentUS11312477B2Aircraft propeller electric blade pitch change and control

Publication Date: 2022.04.26 HAMILTON SUNDSTRAND CORP

AI summary

A propeller assembly of an aircraft includes a hub, a plurality of propeller blades extending from the hub and secured thereto and a propeller blade pitch change system located at at least one propeller blade of the plurality of propeller blades. The propeller blade pitch change system includes a pitch change actuator located in the propeller blade, and a drive mechanism operably connected to the pitch change actuator and to the propeller blade to urge rotation of the propeller blade about a propeller blade axis.