Integrated Sun Shaft Spline Layout for Wind Turbine Torque Transfer

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Solution Overview

Problem

Existing wind turbine gearboxes with two planetary stages face challenges in efficiently transmitting torque while managing stress and design flexibility.

Innovation Solution

A wind turbine gearbox design featuring a first planetary stage with a rotatable sun gear connected to a planet carrier of a second planetary stage via a spline, allowing for a one-piece sun shaft and planet carrier web, which reduces stress and enhances design freedom.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional multi-part sun shaft design is used, then assembly and manufacturing are simpler, but stress management becomes difficult and design flexibility is limited

Engineering Contradiction:
Improvestress managementVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The sun shaft is designed as a single integrated component that combines the sun gear and shaft functions into one piece. This merging eliminates the need for separate sun gear and shaft components, reducing the number of parts and assembly steps while improving stress distribution and structural integrity throughout the torque transmission path.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated sun shaft serves multiple functions simultaneously: it acts as the sun gear, the rotational shaft, and the torque transmission element. This multi-functionality reduces the overall component count and simplifies the gearbox structure while maintaining or improving strength characteristics.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Power

If a larger diameter sun gear is used to transmit greater torques, then torque capacity increases, but the required space and material resources increase

Engineering Contradiction:
Improvetorque transmission capacityVSAvoidspace requirement
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

By integrating the sun gear and shaft into a single component, the design optimizes the distribution of material throughout the structure. This allows for more efficient use of space and material resources while maintaining the torque transmission capacity, as the integrated design eliminates gaps and weak points between separate components.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If higher-strength materials are used for the sun shaft, then torque transmission capability improves, but manufacturing cost increases

Engineering Contradiction:
Improvematerial strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The integrated sun shaft design allows for optimized material selection and manufacturing processes. By creating a single-component structure, the patent enables the use of cost-effective manufacturing methods such as casting or forging that can produce complex geometries in one step, reducing the need for expensive multi-step assembly processes and high-strength materials.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4189266B1Integrated design of a sun shaft
Publication Date: 2025.05.28 ZF FRIEDRICHSHAFEN AG
  • EP4189266B1 patent drawingFigure 1

AI summary

The invention relates to an assembly, comprising a first planetary stage (101) and a second planetary stage (103), wherein a sun gear (101d) of the first planetary stage (101) and a planet carrier (103b) of the second planetary stage (103) are interconnected for conjoint rotation by means of a spline joint (113). The sun gear (101d) integrally forms inner teeth, and a first cheek of the planet carrier (103b) or a sun shaft (111) integrally connected to the first cheek integrally forms outer teeth of the spline joint (113).