Threaded Adhesive Joint for Compact Planetary Gear Connections

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Solution Overview

Problem

Existing connecting devices for rotating machine parts, particularly in planetary gears, are limited in variability and constructive possibilities, leading to unsatisfactory performance in terms of compactness, manufacturability, and reliability.

Innovation Solution

A planetary gear design featuring internal and external threads with adhesive bonding and roller bearings for secure torque transmission, eliminating the need for additional fasteners and allowing for a compact, versatile construction with various gear ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If multiple bolts arranged on a pitch circle diameter are used to connect two machine parts, then the connection strength is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveconnection strengthVSAvoiddevice complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent extracts the connection function from multiple bolts and consolidates it into a single threaded connection. The internal thread in the first machine part engages with the external thread on the second machine part, eliminating the need for multiple bolts while maintaining connection strength through the threaded engagement mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The threaded connection serves multiple functions simultaneously: it provides mechanical strength through thread engagement, enables adjustable positioning along the threaded portion, and allows for secure fastening through the nut. This multi-functional approach replaces the specialized function of multiple bolts with a single versatile threaded mechanism.

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

2Reliability

If multiple bolts arranged on a pitch circle diameter are used to connect two machine parts, then the connection reliability is improved, but the ease of manufacture deteriorates

Engineering Contradiction:
Improveconnection reliabilityVSAvoidease of manufacture
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the connection function from multiple bolts and consolidates it into a single threaded connection. The internal thread in the first machine part engages with the external thread on the second machine part, eliminating the need for multiple bolts while maintaining connection strength through the threaded engagement mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the connection parameter from multiple discrete bolt positions to a continuous threaded structure. The threaded portion with varying diameters allows for adjustable positioning and secure fastening, providing reliability through parameter variation rather than through the quantity of connection elements.

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If a compact design with smaller pitch circle diameter is pursued, then the device size is reduced, but the gear ratio capability is limited

Engineering Contradiction:
Improvedevice sizeVSAvoidgear ratio capability
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent employs a nested structure where the threaded connection is integrated within the planetary gear assembly. The internal thread in the first machine part and external thread on the second machine part are positioned to engage without increasing the overall pitch circle diameter, allowing compact design while maintaining adjustment capability for gear ratio variation.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent introduces dynamic adjustability through the threaded connection, allowing the gear ratio to be changed without altering the physical size of the planetary gear. The threaded portion enables the second machine part to be positioned at different locations along the thread, providing variable gear ratios within a compact form factor.

Inventive Principle:
Principle #15Dynamics

4Strength

If additional fasteners like bolts or screws are used for secure connection, then the connection strength is improved, but the device complexity and number of parts increase

Engineering Contradiction:
Improveconnection strengthVSAvoidnumber of parts
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the connection function with the structural components themselves. The internal thread is formed as an integral part of the first machine part, and the external thread is formed on the second machine part, eliminating the need for separate fasteners. This merging reduces the number of parts while maintaining connection strength through the threaded engagement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The threaded connection serves multiple functions simultaneously: it provides mechanical strength through thread engagement, enables adjustable positioning along the threaded portion, and allows for secure fastening through the nut. This multi-functional approach replaces the specialized function of multiple bolts with a single versatile threaded mechanism.

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

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 provides a secure, compact, and reliable connection with enhanced manufacturability, enabling larger pitch circle diameters and gear ratios without additional bolts or screws, thus improving the structural integrity and versatility of planetary gear systems.

Implementation Method 1

The external thread (9) is screwed into the internal thread (7), wherein at least one of the internal thread (7) and the external thread (9) is coated with adhesive (11)

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP3179138B1Device and method for connecting two rotating machine parts
Publication Date: 2023.05.10 WITTENSTEIN SE
  • EP3179138B1 patent drawingFigure 1
  • EP3179138B1 patent drawingFigure 2

AI summary

Planetary gear with a device for connecting two machine parts (3, 5), in particular two machine parts (3, 5) made of metal rotatable about the same axis, with a first machine part (3), a second machine part (5), wherein the first machine part (3) has an internal thread (7) and the second machine part (5) has an external thread (9), adhesive (11) which is arranged between the internal thread (7) and the external thread (9).