Helicopter Hybrid Propulsion System Torque Compensation

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Solution Overview

Problem

Existing hybrid propulsion systems for single-engine helicopters face challenges with bulk and mass due to the integration of assistance devices, which also suffer from power limitations and inefficiencies, particularly when dealing with torque losses and emergency power needs.

Innovation Solution

A propulsion system incorporating an assistance device with two electric machines, one acting as a generator to harness energy from the main engine and the other as a motor to deliver additional power to the main gearbox, optimizing energy use and reducing bulk and mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a traditional assistance device with solid-state storage and gas generator is integrated into the helicopter propulsion system, then emergency power assistance capability is improved, but bulk and mass of the system increase significantly

Engineering Contradiction:

Improveemergency power assistance capabilityVSAvoidbulk and mass of propulsion system

Core Design Contradiction:

PowerVSWeight of stationary object

Solution Approach 1:

The patent replaces the traditional mechanical assistance device (gas generator with solid-state storage) with an electric machine system. The electric machine can operate in both motor mode to provide emergency power assistance and generator mode to recover energy, eliminating the need for bulky gas generators and solid fuel storage while maintaining the same emergency power assistance capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electric machine is designed to perform multiple functions: it can operate as a motor to provide emergency power assistance during autorotation or power deficits, and as a generator to recover energy during normal operation or when excess power is available from the main engine. This multi-functionality eliminates the need for separate assistance device components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If assistance power is injected via the free turbine of the main turbine engine, then power delivery to the main rotor is improved, but the system becomes vulnerable to rapid deceleration from aerodynamic friction losses when gas supply fails

Engineering Contradiction:

Improvepower delivery to main rotorVSAvoidsystem stability during gas supply failure

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent extracts the assistance power injection point from the free turbine of the main turbine engine and relocates it to the main rotor drive shaft or transmission system. This separation allows the electric machine to provide assistance power independently of the main engine's gas supply status, preventing rapid deceleration when gas supply fails while maintaining effective power delivery to the main rotor.

Inventive Principle:

Principle #2Taking out (Extraction)

3Power

If the helicopter operates at low ambient temperatures and low altitude, then engine power output is improved, but the torque transmitted through the reduction gearbox and main gearbox becomes limited by design torque values

Engineering Contradiction:

Improveengine power outputVSAvoidtorque limitation through reduction gearbox

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an electric machine as an intermediary power source that can directly assist the main rotor drive shaft or transmission system. This electric machine bypasses the torque limitations of the reduction gearbox by providing additional power in parallel with the main engine, allowing the system to exceed the design torque values of the gearbox while operating at low temperatures and altitudes where the main engine produces high power output.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 efficient energy compensation for torque losses, provides additional power during emergencies, and maintains system performance without increasing bulk or mass, thereby enhancing the helicopter's operational capabilities.

Implementation Method 1

a first electric machine mechanically coupled to the reduction gearbox and configured to operate as an electric generator to take off energy produced by the main engine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a second electric machine mechanically coupled to a second input of the main gearbox, the second electric machine being supplied with electrical power by the first electric machine and configured to operate as an electric motor to deliver additional mechanical power to the main gearbox

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12208912B2Hybrid propulsion system for a helicopter

Publication Date: 2025.01.28 SAFRAN HELICOPTER ENGINES

AI summary

Propulsion system for a helicopter comprising a main engine, a main rotor, a main gearbox including an output mechanically connected to the main rotor, a reduction gearbox mechanically coupled between the main engine and a first input of the main gearbox, and an assistance device. The assistance device comprises a first electric machine mechanically coupled to the reduction gearbox and configured to operate as an electric generator to take off energy produced by the main engine, and a second electric machine mechanically coupled to a second input of the main gearbox, the second electric machine being supplied with electrical power by the first electric machine and configured to operate as an electric motor to deliver additional mechanical power to the main gearbox.