Internal Planetary Gear Split Input Shaft Integration

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Solution Overview

Problem

Existing internal planetary reduction gears face limitations in reduction range and installation volume due to constraints such as non-terminating decimal errors in reduction ratio calculations, increased manufacturing costs, limited inner diameter for input shaft insertion, and the need for separate auxiliary structures for low reduction ratios.

Innovation Solution

An internal planetary reduction gear design featuring an integrated main body with internal gears, a split input shaft module allowing easy installation without auxiliary structures, and a configuration of isotropic 1-stage planetary gears and crank shafts with D-cut processed portions to enhance speed reduction and prevent idling, along with a precession prevention plate and vibration prevention pins for stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the 1-stage reduction gear is located at the output end side, then the speed reducer may be easily applied to a high reduction ratio, but the inner diameter of the insertion space is quite limited and manufacturing costs increase due to multiple sealing components

Engineering Contradiction:
Improvereduction ratio rangeVSAvoidinsertion space inner diameter
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent inverts the conventional arrangement by placing the 1-stage reduction gear at the input end side instead of the output end side. This inversion allows the input shaft to have a larger inner diameter for easier installation while maintaining adaptability to different reduction ratios through the modular planetary gear configuration

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

2Adaptability or versatility

If the 1-stage reduction gear is located at the output end side, then high reduction ratio is achieved, but separate sealing components are provided on outer circumferential surface of each 1-stage reduction gear increasing manufacturing costs and weight

Engineering Contradiction:
Improvereduction ratio capabilityVSAvoidnumber of sealing components
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the sealing function into the integrated main body structure. The housing forms a unified sealed enclosure that contains all planetary gears and crank shafts, eliminating the need for multiple separate sealing components on each reduction gear stage, thereby reducing complexity and weight

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If pin gear is employed, then the structure is simple, but the number of pins to be accommodated is limited due to the diameter of pin (about 2 mm) which much limits the reduction range

Engineering Contradiction:
Improvestructural simplicityVSAvoidreduction range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter of the power transmission element from pin gears to planetary gears with crank shafts. This parameter change enables accommodation of more transmission elements within the same space, significantly expanding the reduction range while maintaining structural simplicity through the standardized planetary gear configuration

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If the input shaft is provided as one body, then manufacturing is simplified, but when tooth shape on outer circumferential surface is greater than space at center, the input shaft is unable to pass through center space requiring separate auxiliary structure

Engineering Contradiction:
Improveinput shaft manufacturingVSAvoidinput shaft installation
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent segments the input shaft into two separate parts: a first input shaft and a second input shaft. This segmentation allows the shaft assembly to pass through the center space of the housing during installation, after which the two parts are coupled together. This resolves the installation constraint while maintaining manufacturing simplicity through standardized coupling mechanisms

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3306133B1Internal planetary reduction gear
Publication Date: 2022.08.10 SEJIN IGB CO LTD
  • EP3306133B1 patent drawingFigure 1
  • EP3306133B1 patent drawingFigure 2
  • EP3306133B1 patent drawingFigure 3

AI summary

Disclosed is an internal planetary reduction gear. The internal planetary reduction gear according to an embodiment of the present invention comprises: an internal-gear integrated main body that has an internal gear integrally formed on the inner wall thereof and is provided with a plurality of components for speed reduction; an input shaft module formed as a single body by coupling at least two separated parts with each other, wherein the input shaft module has an input gear formed on an end portion thereof and is connected to the internal-gear integrated main body to receive rotary power from a motor that is connected to the exterior of the internal-gear integrated main body; and an output shaft module that is connected to the input shaft module to interact therewith and reduces the speed of the rotary power of the motor, which is input from the input shaft module, to output the same.