Double Splined Coupling With Crowned Splines for Engine Core Misalignment

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing turbine engines face challenges in integrating an electric machine within the engine core, particularly in coupling rotating components like the electric machine or gearbox with the turbine engine shaft effectively.

Innovation Solution

A double splined coupler, such as a double articulation quill shaft, is used to connect rotating structures within the turbine engine, incorporating crowned spline connections to accommodate axial misalignment and operational shifts, and a flexible coupling for additional flexibility, along with a seal assembly to isolate compartments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the electric machine is arranged within the engine core, then the overall size of the gas turbine engine is reduced, but the complexity of coupling rotating components increases

Engineering Contradiction:
Improveoverall engine sizeVSAvoidcoupling structure complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The double splined coupler is arranged within the engine core, nesting the electric machine coupling mechanism inside the existing turbine engine structure. This allows the electric machine to be integrated within the core rather than externally, reducing overall engine volume while maintaining functional coupling capabilities through the nested splined connection system

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The coupler is divided into multiple segments including a first spline connection for connecting to the turbine engine shaft and a second spline connection for connecting to the electric machine. This segmentation allows each spline connection to be optimized independently for its specific coupling requirements, managing the complexity of integrating multiple rotating components within the constrained engine core space

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If crowned spline connections are used to accommodate axial misalignment, then the adaptability of the coupling increases, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveaccommodation of axial misalignmentVSAvoidspline connection precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The spline connections incorporate crowned surfaces with curved geometries rather than flat surfaces. This curvature allows the spline teeth to maintain contact and transmit torque even when axial misalignment occurs between the turbine engine shaft and the electric machine, providing adaptability to operational shifts while the precise crowning geometry ensures proper load distribution across the spline interface

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If a flexible coupling is incorporated, then the reliability of the connection increases, but the device complexity increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidcoupling mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The coupler incorporates flexible elements that allow dynamic adjustment and movement to accommodate operational variations and misalignments between the turbine engine shaft and the electric machine. This flexibility enhances the reliability of the connection by allowing the coupling to adapt to changing operational conditions, while the flexible design is integrated into the overall coupler structure to manage complexity

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4166774B1Double splined coupling for a turbine engine
Publication Date: 2025.07.16 RTX CORP
  • EP4166774B1 patent drawingFigure 1
  • EP4166774B1 patent drawingFigure 1B
  • EP4166774B1 patent drawingFigure 2~3C

AI summary

An assembly is provided for a turbine engine. This turbine engine assembly includes a turbine engine shaft, a gearbox and a coupler. The turbine engine shaft is configured to rotate about a rotational axis. The gearbox includes a gear configured to rotate about the rotational axis. The coupler is coupled to the turbine engine shaft by a coupler-shaft connection. The coupler-shaft connection is configured as or otherwise includes a crowned spline connection. The coupler is coupled to the gear by a coupler-gear connection. The coupler-gear connection is configured as or otherwise includes a crowned spline connection.