Planetary Gear Planar Spline Coupling for Compact Torque Transfer

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Solution Overview

Problem

Existing planetary gears in wind turbines and industrial applications face challenges in minimizing installation space and optimizing production costs, particularly in torque transmission designs.

Innovation Solution

The use of planar serrations (spur toothing) between the sun shaft and planet carrier, eliminating the need for a hub and allowing for direct or indirect connection via fastening elements, reduces axial and radial space requirements while simplifying production and logistics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional coupling toothing is used between sun shaft and planet carrier, then torque transmission is achieved, but axial and radial installation space is increased

Engineering Contradiction:
Improveinstallation spaceVSAvoidcoupling structure
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent merges the coupling toothing directly into the sun shaft and planet carrier components themselves, eliminating the need for separate coupling hubs. The planar spline toothing is integrated as part of the sun shaft outer circumference and planet carrier inner circumference, reducing the number of discrete parts and minimizing installation space while maintaining torque transmission functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the intermediate coupling hub from the torque transmission path between sun shaft and planet carrier. By directly engaging the planar spline toothing on the sun shaft with the corresponding toothing on the planet carrier, the design removes unnecessary components that would occupy axial and radial space, achieving a more compact configuration.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of manufacture

If a hub is used to connect sun shaft and planet carrier, then connection is achieved, but material usage and manufacturing cost increase

Engineering Contradiction:
Improvemanufacturing costVSAvoidmaterial usage
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent removes the intermediate coupling hub from the design, directly connecting the sun shaft to the planet carrier through integrated planar spline toothing. This elimination of the hub component reduces material consumption and simplifies manufacturing processes, lowering production costs while maintaining structural integrity and torque transmission capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent combines the functions of the sun shaft, planet carrier, and coupling hub into integrated components. The sun shaft and planet carrier are designed with built-in planar spline toothing that directly engages, merging multiple functions into fewer components. This integration reduces the total material required and simplifies manufacturing operations.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If hub and planet carrier are processed separately, then manufacturing flexibility is improved, but logistics cost increases

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidlogistics cost
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The patent merges the manufacturing process by enabling the planet carrier to be produced as a single integrated piece that includes the toothing engagement surfaces. This consolidation allows the entire planet carrier to be machined in one setup or as a single casting/forging operation, eliminating the need to separately manufacture and transport a separate hub component, thereby reducing logistics costs while maintaining manufacturing flexibility.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3734112B1Planetary gear
Publication Date: 2024.09.11 FLENDER GMBH
  • EP3734112B1 patent drawingFigure 1
  • EP3734112B1 patent drawingFigure 2
  • EP3734112B1 patent drawingFigure 3

AI summary

The invention relates to a planetary gear (1) with at least two planetary stages, wherein a sun shaft (2) of a planetary stage is connected to a planet carrier (3) of a second gear stage following the first gear stage via a coupling toothing for torque transmission, characterized in that the coupling toothing is a planar spline toothing. The invention further relates to a drive train (24) of a wind turbine (20) in which a corresponding planetary gear (1) is used as a gearbox. Furthermore, the invention relates to a wind turbine (20) equipped with a corresponding drive train (24). Finally, the invention relates to an industrial application (26) which has a corresponding planetary gear (1) as a gearbox (1).