Truncated Cone Planetary Pin for Space-Constrained Assembly

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Solution Overview

Problem

The existing methods for assembling and disassembling planetary bolts on planetary carriers are cumbersome, requiring significant space and effort, especially in inaccessible locations like wind turbines, due to the difficulty in achieving a precise fit between conical bores and bolts with different diameters.

Innovation Solution

A truncated cone-shaped planetary bolt with a stepped taper is designed to fit securely into conical bores of a planetary carrier with two cheeks, allowing for equal prestressing and using oil interference fits to reduce assembly force, facilitated by supply bores for oil distribution, enabling easy assembly and disassembly with minimal space requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If planetary bolts are shrunk into the planetary carrier using conventional methods, then the planetary gear can be assembled and disassembled, but large hydraulic cylinders and significant space are required, making maintenance difficult in inaccessible locations

Engineering Contradiction:
Improveease of assembly and disassemblyVSAvoidspace requirement for assembly tools
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The planetary bolt is segmented into two distinct parts: a tapered end portion for insertion into the first conical bore, and a widened end portion with a smaller diameter for insertion into the second conical bore. This segmentation allows the bolt to be installed through a sequence of progressively smaller openings, eliminating the need for large hydraulic cylinders and enabling maintenance in confined spaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using a single large opening that requires large assembly tools, the invention inverts the approach by using multiple openings with decreasing diameters. The bolt is inserted backwards through the sequence of bores (first through the larger first bore, then through the smaller second bore), allowing assembly with minimal space requirements.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If conventional shrinking methods are used for planetary bolts, then the bolts can be fixed to the carrier, but the process is cumbersome and requires considerable effort and mechanical aids

Engineering Contradiction:
Improvefixing reliabilityVSAvoidcomplexity of assembly process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The planetary bolt is divided into a tapered end portion and a widened end portion, each designed to fit specific conical bores. This segmentation creates multiple interference fit interfaces that collectively provide reliable fixation while simplifying the assembly process to a straightforward sequential insertion without requiring complex mechanical aids.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the bolt by creating a stepped diameter profile with different conical sections. The tapered end portion has a larger cone angle for the first bore, while the widened end portion has a smaller cone angle for the second bore. This parameter variation enables reliable fixation through interference fits while simplifying the assembly process.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If equal prestressing is required on both cheeks of the planetary carrier, then the planetary gear operates reliably, but conventional methods make it difficult to achieve equal prestressing with different bore diameters

Engineering Contradiction:
Improveequal prestressingVSAvoidmanufacturing difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The planetary bolt features local quality variations with different conical sections: the tapered end portion has a first cone angle matched to the first conical bore, while the widened end portion has a second cone angle matched to the second conical bore. This local differentiation in geometric parameters enables each section to create equal interference fits and prestressing forces in its respective bore, achieving reliable equal prestressing on both cheeks.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention applies parameter changes by defining different cone angles for different sections of the same bolt. The first conical section has a larger cone angle for the first bore, while the second conical section has a smaller cone angle for the second bore. This parameter optimization ensures that both interference fits generate equal prestressing forces, achieving reliable equal prestressing while simplifying the manufacturing process.

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

The solution allows for simple, space-saving, and cost-effective assembly and disassembly of planetary bolts, reducing the need for large hydraulic cylinders and enabling efficient maintenance in constrained environments by ensuring equal prestressing forces on both cheeks of the planetary carrier.

Implementation Method 1

using oil interference fits to reduce assembly force

Methodology Applied
Scientific EffectOil interference fit: Lubrication

Data Source

PatentEP2438327B1Planetary pin, planetary carrier, planetary gear mechanism, and method for the rotationally fixed fastening of a planetary pin to a planetary carrier
Publication Date: 2013.08.21 EICKHOFF ANTRIEBSTECHN GMBH
  • EP2438327B1 patent drawingFigure 1

AI summary

The invention relates to a planetary pin (1) for arranging a planetary gear (20) on a planetary carrier (10) with two cheeks (11, 12), characterized in that the planetary pin (1) is of frustoconical configuration, wherein the planetary pin (1) has a step-shaped tapered section (3) at its widened end in order to receive a circumferential connecting element (30). Furthermore, the invention relates to a planetary carrier (10), a planetary gear mechanism and a method for the rotationally fixed fastening of a planetary pin (1) of a planetary gear (20) of a planetary gear mechanism to a planetary carrier (10).