Wave Generator Plug Support Ring for Large Hollow Strain Wave Gears

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Solution Overview

Problem

The existing wave generators for strain wave gearings face challenges in maintaining rigidity and preventing deformation during manufacturing and operation, especially when increasing the hollow diameter, which leads to improper meshing between gears under load.

Innovation Solution

A wave generator with a cylindrical rigid plug and a high-rigidity plug support ring, formed from materials like cemented carbide or ceramics, is used to maintain the shape and prevent deformation, allowing for a larger hollow part while ensuring proper meshing between the externally and internally toothed gears.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the inner diameter of the hollow part is increased to increase the hollow diameter of the strain wave gearing, then the hollow diameter is improved, but the thickness of the plug in the radial direction is reduced and the rigidity decreases

Engineering Contradiction:
Improvehollow diameterVSAvoidrigidity of plug
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The invention uses a composite structure consisting of a rigid plug made from iron-based material and a plug support ring made from high-rigidity material (more rigid than the iron-based material). This composite structure allows the hollow diameter to be increased while the plug support ring provides additional rigidity support to prevent deformation of the plug during manufacturing and operation.

Inventive Principle:
Principle #40Composite materials

2Length of stationary object

If the thickness of the plug is reduced to increase the hollow diameter, then the hollow diameter is improved, but the plug deforms during manufacturing process and operation

Engineering Contradiction:
Improvehollow diameterVSAvoidshape stability of plug
Core Design Contradiction:
Length of stationary objectVSStability of the object's composition

Solution Approach 1:

The composite structure of the rigid plug and plug support ring provides enhanced shape stability. The plug support ring, being more rigid than the iron-based plug material, prevents radial deformation of the plug during the press-fitting manufacturing process and maintains shape stability when large loads are applied during operation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The wave generator is segmented into multiple functional components: the rigid plug, the plug support ring, and the wave-generator bearing. This segmentation allows each component to perform its specific function - the plug provides the hollow structure, the support ring provides rigidity and shape stability, and the bearing enables rotation - thereby solving the deformation problem without compromising the hollow diameter.

Inventive Principle:
Principle #1Segmentation

3Length of stationary object

If the plug is deformed radially under load, then the hollow diameter is maintained, but the flexing shape of the externally toothed gear changes and proper meshing cannot be maintained

Engineering Contradiction:
Improvehollow diameterVSAvoidmeshing reliability
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

The high-rigidity plug support ring prevents radial deformation of the rigid plug when large loads are applied during operation. By maintaining the circular shape of the plug, the externally toothed gear maintains its proper flexing shape, ensuring reliable meshing with the internally toothed gear throughout the operating cycle.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3351822B1Wave motion generator for wave motion gear device
Publication Date: 2021.05.26 HARMONIC DRIVE SYST IND CO LTD
  • EP3351822B1 patent drawingFigure 1(a)~1(b)
  • EP3351822B1 patent drawingFigure 2

AI summary

A wave generator (5) for a strain wave gearing (1) makes a flexible externally toothed gear (4) to flex into an elliptical shape and mesh with rigid internally toothed gears (2, 3), and makes meshing positions of the flexible externally toothed gear with the both gears (2, 3) to move in a circumferential direction. On the inner side of a rigid plug (6) of the wave generator (5), a plug support ring (11) is secured and integrated. The rigid plug (6) is formed from an iron-based material, and the plug support ring (11) is formed from a high-rigidity material that is more rigid than the iron-based material. Since deformation of the rigid plug (6) is suppressed, the wave generator (5) provided with a large hollow part (9) can be obtained.