Harmonic Reducer Flexspline Assembly for High Torque in Compact Axial Space

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Solution Overview

Problem

Conventional harmonic reducers suffer from large axial dimensions and poor driving torque due to the rigidity of the flange, leading to inefficient tooth engagement and increased axial length, which complicates mass production and reduces transmission efficiency.

Innovation Solution

A novel harmonic reducer design separates the flexible gear from a torque transmission member, incorporating a deformable elastic portion to enhance flexibility and uniform deformation, allowing nearly full tooth engagement and improved torque transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the axial length of the flexible gear is increased to improve torque transmission, then the torque transmission capacity is improved, but the axial dimension of the harmonic reducer becomes larger

Engineering Contradiction:
Improvetorque transmission capacityVSAvoidaxial dimension
Core Design Contradiction:
PowerVSLength of moving object

Solution Approach 1:

The flexible gear is divided into multiple independent thin-walled sections (first, second, third sections) along the axial direction, each capable of deforming independently. This segmentation allows the gear to achieve full tooth engagement and high torque transmission without requiring excessive axial length, as each section contributes to the overall deformation and engagement capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the flexible gear are designed with different structural characteristics - the first section has a larger diameter with a first flange for stability, the second section has optimized wall thickness for deformation, and the third section has a smaller diameter with a second flange for connection. This local differentiation allows each section to perform its specific function optimally, achieving high torque transmission with compact overall dimensions.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If the flange is made rigid to maintain structural stability, then the structural stability is improved, but the radial deformation capability deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidradial deformation capability
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The flanges are designed with localized thin-walled structures at specific positions rather than being completely rigid. The first flange has a first thin-walled section and the second flange has a second thin-walled section, allowing these localized areas to deform radially while the overall flange structure maintains stability. This enables the flanges to provide both structural support and deformation capability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The flanges are segmented into multiple functional zones - rigid connection areas for structural stability and thin-walled deformation areas for radial flexibility. This segmentation allows the flange to simultaneously achieve structural stability for mounting and radial deformation capability for tooth engagement during wave generator rotation.

Inventive Principle:
Principle #1Segmentation

3Stability of the object's composition

If the flexible gear is designed as an integrated thin-walled elastic structure to improve deformation uniformity, then the deformation uniformity is improved, but the manufacturing difficulty increases

Engineering Contradiction:
Improvedeformation uniformityVSAvoidmanufacturing difficulty
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The flexible gear is divided into multiple separate thin-walled sections that can be manufactured independently using standard machining processes, then assembled together. This segmentation makes manufacturing easier compared to creating a single complex integrated structure, while the precise connection interfaces ensure uniform deformation across all sections when assembled.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple independently manufactured thin-walled sections are combined through precise connection interfaces (flanges with mounting holes) to form the complete flexible gear. This merging of separately manufactured components achieves the deformation uniformity of an integrated structure while maintaining the manufacturing ease of individual standard parts.

Inventive Principle:
Principle #5Merging (Combining)

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 design reduces the axial dimension and weight of the harmonic reducer while maintaining deformation safety and extending service life, enhancing torque transmission capacity and efficiency.

Implementation Method 1

a deformable elastic portion (132)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4707640A1New harmonic reducer, flexspline assembly and robot
Publication Date: 2026.03.11 SHENZHEN TONGCHUAN TECHNOLOGY CO LTD
  • EP4707640A1 patent drawingFigure 1
  • EP4707640A1 patent drawingFigure 2
  • EP4707640A1 patent drawingFigure 3

AI summary

The present application relates to a novel harmonic reducer, a flexible gear assembly, and a robot. The harmonic reducer device includes a rigid gear, a flexible gear, a wave generator, and a torque transmission member. The wave generator is positioned within the rigid gear, and the flexible gear is placed between the rigid gear and the wave generator, such that the flexible gear is deformed by the protrusions of the wave generator, such that the external gear of the flexible gear, corresponding to the protrusions, is partially engaged with the internal gear of the rigid gear. The input connection portion of the torque transmission member is joined to the torque output portion of the flexible gear, while the output connection portion of the torque transmission member is connected to a fixed connector to transmit torque. The deformable elastic portion of the torque transmission member is designed to deform simultaneously with the flexible gear.