Composite Wave Gear Drive Backlash-Free Low Reduction Ratio
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Solution Overview
Problem
Existing low-reduction-ratio gear drives suffer from backlash, and conventional wave gear drives that are backlash-free typically have high reduction ratios, making them unsuitable for low-reduction-ratio applications.
Innovation Solution
A composite wave gear drive comprising coaxially disposed circular splines and a flexspline, with wave generators that radially bend flexspline portions to mesh with circular splines, setting the number of teeth such that Nc2 > Nc1 > Nf, and utilizing a shared flexspline structure to achieve backlash-free operation at both low and high reduction ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wave gear drives are used to achieve backlash-free operation, then zero backlash is obtained, but the reduction ratio becomes high (1/50 or higher)
Solution Approach 1:
The wave gear drive is segmented into two independent meshing systems: a first wave generator meshing with a first circular spline, and a second wave generator meshing with a second circular spline. Each system operates independently to provide speed reduction, and their combined effect achieves the desired low reduction ratio while maintaining backlash-free operation through the elastic deformation of the shared flexspline.
Solution Approach 2:
Two wave gear drive systems are merged into a single composite structure by sharing the flexspline as a common component. The first and second wave generators simultaneously deform the flexspline to mesh with their respective circular splines, combining the reduction effects of both systems to achieve a low overall reduction ratio while preserving the backlash-free characteristic.
2Device complexity
If a single wave gear system is used, then the structure is simple, but the reduction ratio becomes high and unsuitable for low-reduction-ratio applications
Solution Approach 1:
The flexspline serves multiple functions: it is simultaneously engaged by both the first and second wave generators, acting as both the deformable element for the first meshing system and the deformable element for the second meshing system. This multi-functionality allows the single flexspline to enable two independent reduction mechanisms, achieving low reduction ratio without proportionally increasing structural complexity.
3Productivity
If existing low-reduction-ratio gear drives are used, then the reduction ratio is appropriate, but backlash occurs
Solution Approach 1:
The invention changes the fundamental operating parameter of the gear drive by using elastic deformation of the flexspline instead of rigid gear meshing. The flexspline's ability to elastically deform under the action of wave generators creates continuous contact between the flexspline teeth and circular spline teeth, eliminating backlash while enabling low reduction ratios through the coordinated action of two wave generators.
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 composite wave gear drive achieves backlash-free operation at both low and high reduction ratios, with the flexspline's elliptical shape and specific tooth configuration ensuring zero backlash and efficient speed reduction.
Implementation Method 1
the flexspline is a shared component of unitary construction... cause the flexspline bend into an elliptical shape
Data Source
AI summary
In a composite wave gear drive, a flexspline (having a number of teeth Nf) is disposed on the inner side of first and second circular splines (numbers of teeth Nc1 and Nc2, respectively). One side of the flexspline is bent into an elliptical shape by a first wave generator, the other side of the flexspline is bent into an elliptical shape by a second wave generator, and the flexspline meshes with the first and second circular splines. The first wave generator is a rotational input component, the second wave generator is a reduced-speed rotational output component, and the first and second circular splines are kept from rotating. The number of teeth is set such that Nc2=Nc1+2 and Nc1=Nf+2. A backlash-free gear drive having a low reduction ratio can be obtained.