Circular Wave Drive with Eccentric Gearing for Low Backlash
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Solution Overview
Problem
Current power transmission and speed reduction devices, such as harmonic and cycloidal drives, face issues like material fatigue, complex construction, vibration, and gear backlash, which limit their performance and lifespan.
Innovation Solution
The circular wave drive system, comprising a compliant input ring gear, input and output cycloidal discs, a primary drive gear with a compliant radial wall, and an eccentric motion generator, provides a simpler, compact design with low backlash and a wide range of speed reduction ratios without the need for rollers, using an eccentric motion generator to achieve efficient speed reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a harmonic drive is used for power transmission and speed reduction, then torque transfer capability is improved, but the flexspine material fatigues from repeated deformation which limits the device lifespan and performance
Solution Approach 1:
The patent changes the fundamental operating parameter from repeated elastic deformation to rigid body motion with controlled engagement. The wave generator creates a moving wave pattern that sequentially engages and disengages teeth, allowing components to maintain their shape while achieving the necessary motion and torque transfer, thereby eliminating fatigue-related lifespan limitations
Solution Approach 2:
The gear system is segmented into distinct engagement zones where teeth interact in a sequential manner rather than simultaneous continuous deformation. This segmentation allows each tooth pair to engage and disengage in sequence, transferring torque through controlled contact rather than continuous material deformation, thus preventing fatigue accumulation
2Force
If a cycloidal drive is used for power transmission and speed reduction, then torque transfer capability is improved, but the construction becomes complex with many moving parts that increase the likelihood of failure
Solution Approach 1:
The patent merges the wave generation function and gear engagement into a single integrated system. The wave generator body itself creates the moving wave pattern that directly engages the gear teeth, eliminating the need for separate rollers, pins, or other intermediary moving parts found in traditional cycloidal drives, thus simplifying the construction while maintaining torque transfer capability
Solution Approach 2:
The wave generator serves multiple functions simultaneously: it generates the moving wave pattern, provides the engagement surface for torque transfer, and acts as the driving element. This multi-functionality reduces the number of dedicated components needed, simplifying the overall device structure while achieving effective power transmission
3Force
If a cycloidal drive is used for power transmission and speed reduction, then torque transfer capability is improved, but eccentric rotation of the cycloidal disc produces undesirable vibration that may be transmitted through the input and output shafts
Solution Approach 1:
The patent converts the potentially harmful eccentric motion into a beneficial controlled wave pattern. By designing the wave generator with intentional eccentricity, the harmful vibration is transformed into a useful moving wave that systematically engages and disengages gear teeth in sequence, achieving torque transfer while the structured nature of the wave minimizes random vibration transmission
4Speed
If toothed gears are utilized to achieve desired reduction ratios, then speed reduction capability is improved, but gear backlash becomes difficult to properly establish
Solution Approach 1:
The patent transitions from static gear engagement to dynamic sequential engagement. The moving wave pattern created by the wave generator causes gear teeth to engage and disengage in a controlled sequence as the wave progresses around the circumference. This dynamic approach allows the system to achieve precise speed reduction ratios while the controlled engagement nature minimizes problematic backlash, as teeth engage progressively rather than with sudden gaps
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 circular wave drive offers a long-lasting, efficient power transmission solution with a wide range of speed reduction ratios, from 8:1 to 10,000:1, minimizing backlash and vibration, and is constructed for durability and simplicity, outperforming existing technologies in terms of performance and lifespan.
Implementation Method 1
a compliant input ring gear having an inner surface, wherein the compliant input ring gear includes internal input ring gear teeth oriented on the inner surface... a compliant primary drive gear having an outer surface, wherein the primary drive gear includes external primary drive gear teeth oriented on the outer surface
Implementation Method 2
an eccentric motion generator, wherein the eccentric motion generator includes an eccentric portion and a non-eccentric portion and wherein a centerline of the eccentric portion and the non-eccentric portion are offset from one another
Data Source
AI summary
A circular wave drive system is provided. In one aspect, the circular wave drive includes a compliant input ring gear having an inner surface having internal input ring gear teeth; an input cycloidal disc having an outer surface having external input cycloidal disc gear teeth oriented on the outer surface, and wherein the external input cycloidal disc gear teeth at least partially engage the internal input ring gear teeth; a compliant primary drive gear having an outer surface having external primary drive gear teeth; an eccentric motion generator including an eccentric portion and a non-eccentric portion and wherein a centerline of the eccentric portion and the non-eccentric portion are offset from one another; and an output cycloidal disc having an inner surface with internal output cycloidal disc teeth, and wherein the internal output cycloidal disc teeth at least partially engage the external primary drive gear teeth.