Wave Gear Drive Ratio Switching for Variable Load Conditions

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Solution Overview

Problem

Existing stress shaft transmissions have fixed transmission ratios, limiting their versatility and adaptability to varying load and dynamic requirements.

Innovation Solution

A stress wave transmission system with at least one clutch that allows switching between two different transmission ratios, and optionally multiple ratios, by varying the number of teeth on the flexspline and circular spline toothing, enabling flexible adaptation to different load and dynamic conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed transmission ratio is used in the tension wave gear, then the structure is simple and reliable, but the adaptability to varying load and dynamic requirements is limited

Engineering Contradiction:
Improveadaptability to varying load and dynamic requirementsVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the transmission ratio variable rather than fixed. The tension wave gear mechanism allows continuous adjustment of the transmission ratio by controlling the deformation of the flexspline, enabling the system to adapt to varying load and dynamic requirements. The wave generator creates a moving deformation pattern in the flexspline that can be modulated to achieve different transmission ratios, transforming a static mechanical system into a dynamic one.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by varying the transmission ratio through controlled deformation of the flexspline. By changing the amplitude and frequency of the wave generator's motion, the system can adjust the number of engaged tooth pairs and the deformation magnitude, thereby changing the effective transmission ratio. This allows the same physical structure to operate at multiple transmission ratios without mechanical reconfiguration.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple flexspline gears with different numbers of teeth are used to achieve different transmission ratios, then versatility is improved, but the device complexity increases due to multiple clutches and switching mechanisms

Engineering Contradiction:
Improvetransmission ratio variabilityVSAvoidclutch and switching mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a single flexspline that can perform multiple functions - engaging with different circular splines to provide various transmission ratios. Instead of requiring separate clutch mechanisms for each gear ratio, the flexspline itself becomes a multi-functional element that can selectively engage with multiple circular splines of different tooth counts, allowing one component to replace what would traditionally require multiple components and switching mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges multiple gear ratio functions into a single integrated mechanism. By combining the flexspline with multiple circular splines in one assembly, the system eliminates the need for separate clutch mechanisms and switching devices. The flexspline acts as a common interface that can simultaneously or selectively engage with different circular splines, merging what would be separate transmission paths into a unified structure.

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

Enables flexible adjustment of transmission ratios to match changing load and dynamic conditions, allowing for efficient operation across a range of applications without fundamental restrictions on the number of teeth or transmission ratios, and can operate with or without a clutch.

Implementation Method 1

The shaft generator bends the rolling bearing and the flex spline into an oval shape, thus engaging the teeth of the circular spline and the flex spline along the vertical axis of the oval shaft generator.

Methodology Applied
Scientific EffectMechanical deformation: Deformation

Implementation Method 2

When the shaft generator rotates, the outer surface of the flexspline rolls along the inner surface of the circularspline, with the teeth of the flexspline engaging and disengaging with the teeth of the circularspline on opposite sides.

Methodology Applied
Scientific EffectRolling motion: Roller

Data Source

PatentEP3892889A1Wave gear drive
Publication Date: 2021.10.13 OVALO
  • EP3892889A1 patent drawingFigure 1
  • EP3892889A1 patent drawingFigure 2
  • EP3892889A1 patent drawingFigure 3

AI summary

The invention relates to a tension wave gear characterized in that a first flex spline gear meshes with a first circular spline gear, and a second flex spline gear meshes with a second circular spline gear, wherein the number of teeth of the first flex spline gear differs from the number of teeth of the second flex spline gear. The tension wave gear includes a switching clutch for switching between two different gear ratios of the tension wave gear.