Axially Adjustable Strain Wave Gearing for Torque and Rigidity Tuning

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Solution Overview

Problem

Existing voltage wave transmissions lack flexibility in adjusting parameters such as breakaway torque, idle torque, back friction torque, rigidity, play, and lost motion, which are crucial for optimal performance in applications like robotics and vehicle steering systems.

Innovation Solution

The wave generator in the voltage wave transmission is designed to be axially displaceable relative to the flexspline, allowing for adjustment of these parameters without interrupting operation, enabling selective operation in different settings to optimize torque and rigidity characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the wave generator is fixed relative to the flexspline, then the structure is simple and reliable, but the torque and rigidity parameters cannot be adjusted

Engineering Contradiction:
Improveadjustability of torque and rigidity parametersVSAvoidstructural complexity of wave generator
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The wave generator is designed with axial adjustability, transforming it from a static component to a dynamic one. The adjusting mechanism allows the wave generator to be positioned at different axial locations relative to the flexspline, enabling continuous adjustment of engagement characteristics. This dynamic capability permits optimization of breakaway torque, idle torque, and rigidity parameters according to specific application requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention utilizes parameter changes by varying the axial position of the wave generator. By changing this geometric parameter, the engagement depth and contact characteristics between the wave generator and flexspline teeth are modified, thereby adjusting the transmission parameters such as breakaway torque and rigidity without changing the fundamental structure.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the wave generator is made axially adjustable, then torque and rigidity can be optimized, but the device complexity increases

Engineering Contradiction:
Improveoperational efficiency through parameter optimizationVSAvoidcomplexity of adjustment mechanism
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The wave generator is segmented into distinct functional components: the adjusting mechanism and the shaping element. This segmentation allows the adjusting mechanism to be independently designed and optimized, potentially using simpler mechanisms such as threaded adjustments or spring-loaded positioning, while the shaping element maintains its primary function of deforming the flexspline.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adjusting mechanism introduces controlled dynamics to the otherwise static wave generator. Rather than requiring complex real-time control systems, the mechanism allows for preset positional adjustments that can be made during assembly or maintenance, providing operational flexibility without excessive complexity.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If the axial position of the wave generator is changed, then transmission parameters can be adjusted, but manufacturing precision requirements increase

Engineering Contradiction:
Improveflexibility in operation settingsVSAvoidprecision of axial positioning
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention employs partial action by providing a range of axial positions rather than requiring precise positioning at a single optimal point. The adjusting mechanism allows selection from multiple discrete or continuous positions, where any position within the adjustment range provides functional operation, reducing the stringency of precision requirements compared to a fixed-design approach.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

By making the axial position a variable parameter rather than a fixed dimension, the design accommodates manufacturing tolerances more effectively. The adjusting mechanism compensates for variations in component dimensions, allowing the system to achieve desired transmission parameters through post-assembly adjustment rather than requiring tight 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 design enhances the flexibility and adaptability of voltage wave transmissions, allowing for real-time adjustments to torque and rigidity parameters, improving performance and efficiency in various applications without the need to stop the system.

Implementation Method 1

The usually elliptical wave generator presses the flexspline into an elliptical shape and thus brings the external teeth of the flexspline into engagement with the internal teeth of the circular spline

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

at least one parameter of the tension shaft transmission, for example the breakaway torque, the idle torque, the torque, the back friction torque, the rigidity, the play or the lost motion can be changed by changing the axial position of the shaft generator relative to the Flexspline

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4276332A1Strain wave gearing
Publication Date: 2023.11.15 OVALO
  • EP4276332A1 patent drawingFigure 1
  • EP4276332A1 patent drawingFigure 2
  • EP4276332A1 patent drawingFigure 3

AI summary

The invention relates to a tension wave drive comprising a circular spline, a flex spline, and a wave generator. The invention also relates to an actuator comprising such a tension wave drive and a drive motor. The tension wave drive is characterized in that the wave generator is arranged to be axially displaceable relative to the flex spline.