Partial-Contact Cycloid Gear Assembly for Compact High Reduction
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Solution Overview
Problem
Conventional rolling-contact cycloid and strain-wave gear assemblies face challenges in miniaturization, shock resistance, and transparency, with high complexity and cost due to numerous high-precision parts, making them unsuitable for applications requiring compact size and high shock forces or high transparency.
Innovation Solution
A gear assembly with a partial contact design featuring unequal engagement of pins with transfer members and offset roller bearings, allowing for a higher reduction ratio in a smaller size, using drawn-cup needle roller bearings for cost-effectiveness and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rolling-contact cycloid or strain-wave gear assemblies are used, then high reduction ratio and shock resistance are achieved, but device complexity and cost increase due to numerous high-precision parts
Solution Approach 1:
The gear assembly is segmented into distinct functional components: a first transfer member with cycloidal lobes, a second transfer member, multiple pins distributed around the circumference, and roller bearings positioned at specific locations. This segmentation allows each component to be optimized independently while reducing overall complexity compared to conventional designs.
Solution Approach 2:
Roller bearings are positioned at specific local locations rather than uniformly distributed, creating unequal engagement between pins and transfer members. This local quality approach reduces the number of high-precision parts needed while maintaining shock resistance through strategic placement of bearing support at critical locations.
2Reliability
If conventional rolling-contact cycloid or strain-wave gear assemblies are used, then high reduction ratio is achieved, but device size increases making miniaturization difficult
Solution Approach 1:
The roller bearings engage the pins unequally, with some bearings providing support while others have reduced or no engagement during certain phases of operation. This partial action allows for a higher reduction ratio in a compact size by optimizing the engagement pattern rather than requiring full uniform engagement throughout the entire circumference.
Solution Approach 2:
The gear assembly utilizes the radial dimension effectively with the eccentric arrangement of the second transfer member relative to the first, creating a compact design that achieves high reduction ratio without increasing overall volume. The offset positioning allows torque transmission through a compact radial layout.
3Reliability
If conventional rolling-contact cycloid gear assemblies are used, then shock resistance is achieved, but transparency decreases due to high complexity
Solution Approach 1:
The design extracts only the essential elements needed for shock resistance: a minimal set of roller bearings positioned at critical locations rather than a complete circumferential array. This extraction maintains shock resistance while reducing complexity and improving transparency by eliminating unnecessary high-precision parts.
Solution Approach 2:
The unequal engagement pattern changes the operational parameters of the gear assembly, allowing pins to engage transfer members with varying force distribution. This parameter change enables shock resistance through dynamic load distribution while reducing the number of precision components needed.
Data Source
AI summary
A gear assembly in accordance with at least some embodiments of the present technology includes first and second supports extending circumferentially around an assembly axis in first and second planes, respectively. The gear assembly includes a first transfer member having first lobes and first troughs circumferentially alternating around the assembly axis in a third plane. The gear assembly includes a second transfer member having second lobes and second troughs circumferentially alternating around the assembly axis in a fourth plane. The third and fourth planes are between the first and second planes along the assembly axis. The gear assembly includes first and second pins circumferentially interspersed around the assembly axis and extending between the first and second supports. The gear assembly transfers torque at least primarily via contact between the first pins and the first lobes and via contact between the second pins and the second lobes.