Modular Coaxial Gear Set Reducer for Assembly Precision

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Solution Overview

Problem

Existing planetary gear based reducers face challenges with complicated assembly, insufficient accuracy, and deviation of concentricity, leading to increased machining difficulty, cost, and potential issues with noise and transmission efficiency.

Innovation Solution

A modularized coaxial gear set reduction mechanism is introduced, featuring a housing, transmission axle, internally toothed ring track, and a coaxial gear set comprising a sun gear, planetary gear set, and output member. This modular design simplifies assembly, enhances concentricity, and reduces machining complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If machining precision of each component is heightened to improve concentricity and assembly accuracy, then assembly accuracy and concentricity are improved, but the difficulty of machining and assembling increases, leading to increased overall cost of fabrication

Engineering Contradiction:
ImproveconcentricityVSAvoidmachining difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The reduction mechanism is divided into modular components (planetary gear carrier frame, sun gear, planetary gears, internally toothed ring, housing) that can be manufactured separately with standard tolerances and assembled together. This segmentation allows each component to be machined independently without requiring extremely high precision across the entire assembly, thereby reducing overall machining difficulty while maintaining assembly concentricity.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If machining precision is lowered to reduce manufacturing cost, then overall cost of fabrication is reduced, but situations such as unsecured assembly and poor gear engagement may incur, leading to issues of noise and poor transmission efficiency

Engineering Contradiction:
Improvefabrication costVSAvoidgear engagement quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

By segmenting the mechanism into modular components with standardized interfaces, the patent enables manufacturing at lower cost while ensuring reliable gear engagement through proper modular design. The modular structure allows for easier quality control and assembly verification without requiring ultra-precise machining of every component.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The planetary gears are nested within the planetary gear carrier frame, with the sun gear at the center and planetary gears surrounding it. This nested arrangement ensures proper gear engagement and load distribution, maintaining transmission efficiency and reducing noise even when manufactured with standard tolerances rather than extreme precision.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Device complexity

If a planetary gear based reduction mechanism is assembled with multiple components mounted sequentially, then the reduction mechanism can be constructed, but the assembly process becomes complicated and time-consuming

Engineering Contradiction:
Improveassembly structureVSAvoidassembly time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The reduction mechanism is segmented into distinct modular components (planetary gear carrier frame with mounted planetary gears, sun gear assembly, internally toothed ring, housing) that can be prepared separately and then assembled together in a simplified process. This modular segmentation dramatically reduces assembly complexity and time compared to sequentially mounting individual components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple components are merged into pre-assembled modules - for example, planetary gears are pre-mounted on the planetary gear carrier frame, and the sun gear is prepared as a separate assembly. These merged modules are then easily installed into the housing with the internally toothed ring, simplifying the overall assembly process and reducing assembly time.

Inventive Principle:
Principle #5Merging (Combining)

4Device complexity

If multiple components are assembled to form a reduction mechanism, then the reduction mechanism can be constructed, but inventory management becomes difficult due to the large number of parts

Engineering Contradiction:
Improvenumber of componentsVSAvoidinventory management
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

While the mechanism is segmented into functional modules for assembly purposes, the modular design actually simplifies inventory management by creating standardized, interchangeable components. Each module (planetary gear carrier frame, sun gear, internally toothed ring) can be manufactured as a standard unit and stored separately, making inventory tracking and replacement more efficient than managing numerous small individual parts.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4019805B1Modularized coaxial gear set reduction mechanism
Publication Date: 2025.06.11 YAO LI HO
  • EP4019805B1 patent drawingFigure 1
  • EP4019805B1 patent drawingFigure 2
  • EP4019805B1 patent drawingFigure 3

AI summary

A mechanism includes a housing (10), a transmission axle (15) arranged at a center of the housing (10), an internally toothed ring track (18) fixed to an inner circumference of the housing (10), and a coaxial gear set (20) arranged between the transmission axle (15) and the internally toothed ring track (18). The coaxial gear set (20) includes a sun gear (21), a planetary gear set (30), and an output member (40). The planetary gear set (30) includes a first carrier frame (31) and a second carrier frame (35) rotatably arranged at two ends of the sun gear (21). Multiple planetary gears (33) are rotatably arranged between the first and second carrier frames (31, 35) and around the sun gear (21). Each of the planetary gears (33) is in meshing engagement with the output member (40). The coaxial gear set (20) is made in a modularized form for subsequent assembly in an optional manner, so as to provide an efficacy of easing assembling and servicing operations.