Propeller Feathering via Electric Motor-Driven Pitch Change

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Solution Overview

Problem

Propeller driven aircraft face challenges in feathering the propeller blades during thermal engine shutdown due to increased inertia, leading to drag and adverse air flow effects on control surfaces.

Innovation Solution

A hybrid electric propulsion system with a thermal engine, electric motor, gearbox, and hydro-mechanical pitch change mechanism, where the electric motor operates using electrical power from an electric power storage unit to actuate the pitch change mechanism and feather the propeller blades during thermal engine shutdown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thermal engine is shutdown, then the propeller cannot be feathered properly due to increased inertia, but this causes substantial drag on the aircraft

Engineering Contradiction:

Improvepropeller feathering capabilityVSAvoiddrag

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an electric motor as an intermediary device to actuate the pitch change mechanism during thermal engine shutdown. The electric motor serves as a mediator that can operate independently of the thermal engine's mechanical drive system, enabling the propeller to be feathered when the thermal engine is shutdown. This resolves the contradiction by providing an alternative power source that overcomes the increased inertia problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the thermal engine's mechanical drive system with an electric motor-driven system for actuating the pitch change mechanism. During thermal engine shutdown, the electric motor substitutes for the mechanical propulsion system, providing the necessary torque to rotate the propeller blades to the feathered position. This substitution eliminates the dependency on thermal engine mechanical power for feathering operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the propeller pitch is not properly oriented during thermal engine shutdown, then feathering cannot be achieved, but this produces adverse air flow effects on control surfaces

Engineering Contradiction:

Improvepropeller pitch controlVSAvoidadverse air flow effects

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The electric motor acts as an intermediary control system that can independently adjust propeller pitch orientation during thermal engine shutdown. It provides the necessary control authority to rotate the propeller blades to the correct feathered angle, ensuring proper pitch orientation without relying on the thermal engine's operational state. This resolves the control difficulty by providing an independent actuation system.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If a traditional windmilling gas turbine engine is used, then the propeller can be feathered, but the thermal engine has increased inertia that causes difficulties in feathering during shutdown

Engineering Contradiction:

Improvefeathering speedVSAvoidinertia

Core Design Contradiction:

ProductivityVSForce

Solution Approach 1:

The patent replaces the thermal engine's mechanical inertia-based operation with an electric motor-driven system. The electric motor can rapidly deliver the necessary torque to overcome propeller inertia and achieve quick feathering, eliminating the delay caused by thermal engine inertia. This substitution enables faster response and more reliable feathering operation during shutdown scenarios.

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 effective feathering of propeller blades during thermal engine shutdown, reducing drag and avoiding adverse air flow effects, thereby enhancing aircraft control.

Implementation Method 1

control the electric motor to operate using electrical power from the electric power storage unit to cause the main oil pump to actuate

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

produce a pressurized flow of engine oil to the pitch change mechanism

Methodology Applied

Scientific EffectHydraulic pressure generation: Hydraulic Press

Implementation Method 3

hydro-mechanical pitch change mechanism... produce a pressurized flow of engine oil to the pitch change mechanism for a period of time sufficient for the pitch change mechanism to feather the propeller blades

Methodology Applied

Scientific EffectHydro-mechanical actuation: Hydraulic Press

Data Source

PatentUS12473843B2Hybrid electric propulsion system with pitch change mechanism operation

Publication Date: 2025.11.18 PRATT & WHITNEY CANADA CORP

AI summary

A hybrid electric propulsion system for an aircraft is provided that includes a thermal engine, an electric motor, a gearbox, an electric power storage unit, a propulsion unit, and a controller. The thermal engine has a main oil pump configured to be driven by the thermal engine. The gearbox is in communication with the thermal and electric motors. The propulsion unit includes a propeller having propeller blades, and a pitch change mechanism. The controller is in communication with the thermal and electric motors, the propulsion unit, and a memory storing instructions. The instructions when executed cause the controller to control the electric motor to operate using electrical power from the electric power storage unit to cause the main oil pump to actuate and produce a flow of engine oil to the pitch change mechanism for a period of time sufficient to feather the propeller blades.