Hydraulic Coupling for Hybrid Electric Propulsor Power Transmission

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Solution Overview

Problem

Conventional commercial aircraft propulsion systems face challenges in efficiency and integration, particularly in hybrid electric propulsion systems where further improvements in propulsor efficiency and integration are desired.

Innovation Solution

The implementation of a hybrid electric propulsor system that includes a gas turbine engine and an electric machine, where the electric machine is operatively coupled with the fan spool of the gas turbine engine, and a hydraulic coupling is used to hydraulically couple the fan spool and the core spool, allowing for power transmission between them.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a conventional mechanical gearbox is used to couple the fan spool and core spool, then power transmission is achieved, but the device complexity and noise increase

Engineering Contradiction:
Improvepower transmissionVSAvoiddevice complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent employs a hydraulic coupling device that uses hydraulic fluid to transmit power between the fan spool and core spool. The hydraulic coupling includes a housing containing hydraulic fluid, with the fan spool and core spool immersed in the fluid. Power transmission is achieved through hydraulic coupling rather than direct mechanical gear engagement, thereby eliminating the need for a complex mechanical gearbox while maintaining effective power transfer between the spools.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Power

If a mechanical gearbox is used for power transmission, then the spools are coupled, but noise and emissions increase

Engineering Contradiction:
Improvepower transmissionVSAvoidnoise and emissions
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The hydraulic coupling system replaces mechanical gear transmission with fluid-based power transfer. The hydraulic fluid acts as the transmission medium between the fan spool and core spool, eliminating mechanical gear engagement that generates noise and requires lubrication systems that produce emissions. This hydraulic transmission method significantly reduces operational noise and harmful emissions while maintaining effective power transmission.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Power

If the fan spool and core spool are physically connected via gearbox, then power transmission is achieved, but fuel consumption increases

Engineering Contradiction:
Improvepower transmissionVSAvoidfuel consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The hydraulic coupling provides a more efficient power transmission path compared to mechanical gearboxes. The hydraulic fluid directly transmits power from the core spool to the fan spool with minimal energy loss, eliminating the inefficiencies associated with mechanical gear engagement, friction, and lubrication requirements. This results in reduced fuel consumption while maintaining the necessary power transmission between spools.

Inventive Principle:
Principle #29Pneumatics and hydraulics

4Device complexity

If a hydraulic coupling is used to couple fan spool and core spool, then device complexity is reduced and noise decreases, but the mechanism for power transmission becomes different from conventional systems

Engineering Contradiction:
Improvedevice complexityVSAvoidadaptability to conventional systems
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The hydraulic coupling device is designed to integrate with conventional gas turbine engine architectures while providing simplified power transmission. The coupling housing contains the hydraulic fluid and spools, creating a self-contained unit that can be installed in existing engine configurations. This approach reduces overall device complexity by eliminating the gearbox while maintaining compatibility with conventional engine designs through standardized mounting and operational interfaces.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 enhances propulsor efficiency by allowing independent control of rotational speeds, reduces noise, improves fuel consumption, and decreases emissions, while also eliminating the need for a physical gearbox and enabling an integrated thrust reverse system.

Implementation Method 1

a hydraulic coupling encasing at least a portion of the fan spool and at least a portion of the core spool, the hydraulic coupling hydraulically coupling the fan spool and the core spool

Methodology Applied
Scientific EffectHydraulic coupling: Hydraulic Press

Data Source

PatentEP4015795B1Hybrid electric propulsor equipped with a hydraulic coupling
Publication Date: 2025.02.12 GENERAL ELECTRIC CO
  • EP4015795B1 patent drawingFigure 1
  • EP4015795B1 patent drawingFigure 2
  • EP4015795B1 patent drawingFigure 3

AI summary

A hybrid electric propulsor equipped with a hydraulic coupling is provided. In one aspect, a propulsor includes a gas turbine engine and an electric machine operatively coupled thereto. The gas turbine engine includes a fan spool and a core spool. The electric machine is operatively coupled with the fan spool. A hydraulic coupling defines a sealed volume in which hydraulic transmission fluid is provided. The hydraulic coupling encases at least a portion of the fan spool and at least a portion of the core spool. The hydraulic coupling hydraulically couples the fan spool and the core spool and allows for power transmission between the fan spool and the core spool.