Sun Gear and Planet Carrier Positive-Locking Assembly

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Solution Overview

Problem

Existing methods for joining sun gears and planetary carriers in planetary gears are limited by restricted material choices and unsuitable material pairings, particularly for press fits, which restricts flexibility and increases production costs.

Innovation Solution

A method involving a positive connection between the sun gear and planetary carrier using forming techniques such as rolling, flanging, or roller burnishing to create a secure form-fitting connection, allowing for various material pairings like metal and ceramic or metal and plastic, with optional press fits for enhanced stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If material-bonding methods (welding, brazing, bonding) are used to join sun gear and planet carrier, then the components can be connected securely, but the choice of materials is limited and many material pairings are unsuitable

Engineering Contradiction:
Improveconnection securityVSAvoidmaterial selection flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces material-bonding methods (welding, brazing, bonding) with a mechanical forming process. A tab on the planet carrier is formed over a groove on the sun gear shaft area, creating a positive mechanical connection. This substitution eliminates material compatibility constraints while maintaining secure connection, enabling diverse material pairings such as metal and ceramic or metal and plastic.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If interference fit is used between sun gear and planet carrier, then the components can be connected, but many material pairings are unsuitable or only conditionally suitable

Engineering Contradiction:
Improveconnection securityVSAvoidmaterial pairing compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the interference fit method with a forming process where a tab is deformed over a groove. This mechanical forming approach creates a positive locking connection that is not constrained by material pairing compatibility, allowing any material combination to be joined securely without the limitations inherent in interference fit methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If separate manufacturing and joining of sun gear and planet carrier is performed, then manufacturing flexibility is maintained, but the joining process is complex and costly

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidjoining process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The groove is pre-formed on the sun gear shaft area during sun gear manufacturing, and the tab is subsequently formed over this groove in a single forming operation. This preliminary preparation of the groove simplifies the joining process compared to traditional methods, reducing complexity and cost while maintaining the benefits of separate component manufacturing.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If traditional joining methods are used, then components can be connected, but production time and cost increase

Engineering Contradiction:
Improveconnection securityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces multi-step material-bonding or interference fit processes with a single forming operation where the tab is deformed over the groove. This mechanical forming process significantly reduces production time and cost while achieving secure connections capable of transmitting high torques, thereby improving overall productivity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 method enables simple, inexpensive, and flexible production of sun gear and planetary carrier combinations, allowing for secure connections that can transmit high torques, while enabling the use of diverse materials and improving assembly efficiency.

Implementation Method 1

The component to be deformed, typically the planet carrier, is preferably made of metal. The forming process can be carried out, for example, by rolling, crimping, crimping, embossing, bending, folding or kneading.

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP3832171A1Method for producing a combination from a solar gear and a planetary carrier, and combination produced according to said method
Publication Date: 2021.06.09 MAXON MOTOR AG
  • EP3832171A1 patent drawingFigure 1~3
  • EP3832171A1 patent drawingFigure 4~5
  • EP3832171A1 patent drawingFigure 6~7

AI summary

The present invention relates to a method for manufacturing a system for a planetary gear consisting of a sun gear and a planet carrier, wherein the sun gear and planet carrier are manufactured as separate components and subsequently joined together. According to the invention, the two components are joined together by forming a positive-locking connection between them.