Segmented Flexible Gear Wheel for Low-Backlash Wave Transmission

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Solution Overview

Problem

Existing flexible gear transmissions in the automotive and robotics sectors face issues with tilting of the central gear wheel relative to the ring gear axis, leading to incomplete torque transmission, flank direction errors due to manufacturing tolerances, and geometric deviations, resulting in meshing problems, noise, and reduced service life.

Innovation Solution

The flexible gear wheel is segmented into multiple disks in the axial direction, each with toothed segments connected by spring segments, allowing for radial flexibility and compensation of tilting and manufacturing errors, ensuring full engagement and reduced backlash.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single flexible gear wheel is used, then the structure is simple, but tilting relative to the ring gear axis causes incomplete torque transmission and partial gear engagement

Engineering Contradiction:
Improvegear wheel structureVSAvoidtorque transmission completeness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The flexible gear wheel is divided into multiple gear wheel disks (first, second, third disks) arranged axially. Each disk can tilt independently to compensate for misalignment, ensuring complete torque transmission across all disks while maintaining overall structural simplicity

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If manufacturing tolerances are relaxed, then production cost decreases, but flank direction errors and geometric deviations cause meshing problems

Engineering Contradiction:
Improveproduction toleranceVSAvoidmeshing quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

Dividing the gear wheel into multiple independent disks allows each disk to accommodate manufacturing variations independently. The spring segments connecting the disks provide flexibility to absorb geometric deviations and flank direction errors, maintaining reliable meshing even with relaxed production tolerances

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring segments introduce radial flexibility that allows the gear wheel disks to adjust their positions dynamically. This flexibility compensates for manufacturing tolerances in real-time during operation, ensuring proper meshing conditions are maintained despite variations in production quality

Inventive Principle:
Principle #35Parameter changes

3Power

If the gear wheel width is increased to improve torque transmission, then power capacity increases, but tilting causes only partial width engagement

Engineering Contradiction:
Improvetorque transmission capacityVSAvoidengagement completeness
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The gear wheel is segmented into multiple axial disks, each contributing to torque transmission. This allows the overall power capacity to be increased by adding more disks without suffering from partial engagement issues, as each disk independently maintains full engagement through its ability to tilt and flex radially

Inventive Principle:
Principle #1Segmentation

4Measurement precision

If backlash is reduced to improve precision, then positioning accuracy increases, but manufacturing tolerances cause variable backlash

Engineering Contradiction:
Improvepositioning accuracyVSAvoidbacklash consistency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The spring segments provide radial flexibility that allows the gear wheel disks to maintain consistent backlash compensation despite manufacturing variations. This flexibility ensures that positioning accuracy is maintained with consistent backlash across all disks, overcoming the variability introduced by manufacturing tolerances

Inventive Principle:
Principle #35Parameter changes

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 configuration enhances power transmission, reduces noise, and increases the service life by ensuring full gear engagement and minimizing meshing faults, leading to improved performance and durability.

Implementation Method 1

spring segments connected to one another in the circumferential direction, which are connected to one another by means of spring segments

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3828442A1Flexible toothed wheel and transmission comprising such a flexible toothed wheel
Publication Date: 2021.06.02 MAXON MOTOR AG
  • EP3828442A1 patent drawingFigure 1
  • EP3828442A1 patent drawingFigure 2
  • EP3828442A1 patent drawingFigure 3

AI summary

The present invention relates to a transmission comprising a ring gear, a flexible gear arranged within the ring gear, and a wave generator connected to the flexible gear, which deforms the flexible gear so that it engages with the ring gear in certain areas. The object of the present invention is to improve such a transmission in such a way as to reduce meshing disturbances and backlash, improve noise characteristics and power transmission, and increase service life. To this end, the invention provides that the flexible gear has at least two flexible gear disks arranged axially adjacent to one another, and each gear disk comprises at least two tooth segments circumferentially connected to one another by means of spring segments.