Planetary Joint Transmission Layout for Compact Multi-Ratio Power Transfer
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Solution Overview
Problem
Existing power transmission devices are large in size, which is a challenge for their integration into various devices, particularly joint devices like electric prosthetic legs.
Innovation Solution
A power transmission device with a connection and disconnection mechanism that includes an engagement element between rotation members, an operation unit with an actuation element, and a transmission unit featuring planetary mechanisms, allowing for compact design and multiple power transmission paths with different ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional power transmission device is used, then power transmission function is achieved, but the device size becomes large
Solution Approach 1:
The patent applies nesting by placing the second rotation element inside the first rotation member, and the third rotation element inside the second rotation element. This nested arrangement allows multiple rotation elements to occupy overlapping radial spaces, significantly reducing the overall device volume while maintaining multiple power transmission paths with different transmission ratios
Solution Approach 2:
The patent transitions from a conventional planar arrangement to a three-dimensional nested configuration. By utilizing the radial direction for nesting and the axial direction for stacking, the invention creates multiple power transmission paths in different spatial dimensions, achieving compact size without sacrificing transmission capability
2Adaptability or versatility
If multiple power transmission paths are provided, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent makes the nested rotation elements multi-functional. Each rotation element serves dual purposes: it acts as a rotating component for power transmission and simultaneously serves as a housing or support structure for the next nested element. This multi-functionality reduces the number of separate components needed, simplifying the overall structure while enabling multiple transmission paths
3Volume of moving object
If rotation members are arranged coaxially, then space utilization is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces connection elements as intermediaries between the nested rotation members. These connection elements serve as precision reference features that facilitate accurate coaxial alignment during assembly, reducing the burden on individual component manufacturing precision while achieving the required overall alignment for compact nested arrangement
Data Source
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AI summary
A power transmission device (TM1) includes a connection and disconnection mechanism (20) and a transmission (T). The transmission (T) includes a second planetary mechanism (P2) having a sun gear (SG2), a carrier (PC2), and a ring gear (RG2). The transmission (T) changes in speed of rotation power between a first shaft (181) and a second shaft (182). The carrier (PC2) and the ring gear (RG2) are disposed outward than the second shaft (182) in a radial direction. At least a part of the carrier (PC2) and the ring gear (RG2) overlap the second shaft (182) as viewed in the radial direction.