Tiltable Planet Shaft for Load-Induced Gear Misalignment

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing planetary stages in wind turbines face issues with gear misalignment due to deformations under load, leading to premature failure and increased wear, which requires rigid manufacturing tolerances and higher mass, space, and cost requirements.

Innovation Solution

A tiltable planetary shaft that can be orthogonally tilted relative to the planet carrier, allowing for self-alignment of gears to minimize load-induced misalignment, and a two-piece design for the planetary carrier and shaft for simplified assembly and reduced friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the planetary carrier is designed with high rigidity to maintain gear alignment, then gear misalignment is reduced, but mass and manufacturing costs increase

Engineering Contradiction:
Improvegear alignmentVSAvoidplanetary carrier mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The invention replaces the static rigid fixation of planet gears with a dynamic tilting mechanism. The planet gears are mounted on tiltable planet shafts that can automatically adjust their orientation in response to load-induced deformations, maintaining proper meshing alignment without requiring excessive carrier rigidity or mass.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the mounting parameter from fixed rigid connection to tiltable connection with one degree of freedom. This allows the planet shafts to adapt their angular position dynamically, compensating for deformations and maintaining gear alignment under varying load conditions.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the planetary carrier is designed with high rigidity to maintain gear alignment, then gear misalignment is reduced, but manufacturing costs increase

Engineering Contradiction:
Improvegear alignmentVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces the static rigid fixation of planet gears with a dynamic tilting mechanism. The planet gears are mounted on tiltable planet shafts that can automatically adjust their orientation in response to load-induced deformations, maintaining proper meshing alignment without requiring excessive carrier rigidity or mass.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the mounting parameter from fixed rigid connection to tiltable connection with one degree of freedom. This allows the planet shafts to adapt their angular position dynamically, compensating for deformations and maintaining gear alignment under varying load conditions.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the planet gears are rigidly fixed in the planet carrier, then positioning is precise at rest, but alignment deteriorates under load deviations

Engineering Contradiction:
Improvegear positioningVSAvoidgear alignment under load
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention replaces the static rigid fixation of planet gears with a dynamic tilting mechanism. The planet gears are mounted on tiltable planet shafts that can automatically adjust their orientation in response to load-induced deformations, maintaining proper meshing alignment without requiring excessive carrier rigidity or mass.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The tiltable planet shafts provide self-alignment functionality, automatically adjusting their orientation in response to load-induced deformations without external control. The system self-corrects alignment deviations through the natural tilting motion enabled by the spherical bearing mounting.

Inventive Principle:
Principle #25Self-service

4Weight of moving object

If the planet carrier is designed with reduced mass and space requirements, then cost and efficiency improve, but gear alignment stability deteriorates

Engineering Contradiction:
Improveplanetary carrier massVSAvoidgear alignment stability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The invention replaces the static rigid fixation of planet gears with a dynamic tilting mechanism. The planet gears are mounted on tiltable planet shafts that can automatically adjust their orientation in response to load-induced deformations, maintaining proper meshing alignment without requiring excessive carrier rigidity or mass.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the mounting parameter from fixed rigid connection to tiltable connection with one degree of freedom. This allows the planet shafts to adapt their angular position dynamically, compensating for deformations and maintaining gear alignment under varying load conditions.

Inventive Principle:
Principle #35Parameter changes

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 reduces the need for a stiff planet carrier design, tolerates deformations, minimizes wear, and decreases mass, space, and cost requirements while improving durability and assembly efficiency.

Implementation Method 1

A tiltable planetary shaft that can be orthogonally tilted relative to the planet carrier, allowing for self-alignment of gears to minimize load-induced misalignment

Methodology Applied
Scientific EffectSelf-alignment:

Implementation Method 2

a two-piece design for the planetary carrier and shaft for simplified assembly and reduced friction

Methodology Applied
Scientific EffectFriction reduction:

Data Source

PatentEP3230622B1Pivotally mounted planet shaft
Publication Date: 2021.09.22 ZF FRIEDRICHSHAFEN AG
  • EP3230622B1 patent drawingFigure 1
  • EP3230622B1 patent drawingFigure 2a~2b
  • EP3230622B1 patent drawingFigure 3

AI summary

The invention relates to a planetary stage (101) comprising a planet carrier (119), at least one planetary gear (107, 109), and at least one planet shaft (115); the planetary gear (107, 109) is mounted in the planet shaft (115) in such a way as to be rotatable about an axis of rotation. The planet shaft (115) is secured in the planet carrier (119) in such a way that the planet shaft (115) can be tilted perpendicularly to the axis of rotation relative to at least one part of the planet carrier (119).