Radial Compound Harmonic Drive Assembly With Lower Rotating Inertia
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Solution Overview
Problem
Prior art compound harmonic drives face manufacturing complexity due to axially adjacent gears and high rotating inertia, which reduces system response and increases manufacturing difficulty.
Innovation Solution
A compact compound harmonic drive design with radially adjacent gears, a flex spline with outwardly and inwardly facing teeth, and a wave generator with non-circular inner and outer surface profiles, reducing complexity and inertia while enabling continuous output rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If axially adjacent gears are used in compound harmonic drives, then the drive can achieve high torque output, but the manufacturing complexity increases and the rotating inertia increases
Solution Approach 1:
The patent transitions from axial arrangement of gears to radial arrangement, changing the spatial dimension of gear placement. This dimensional change allows gears to be positioned around the circumference rather than stacked along the axis, reducing manufacturing complexity while maintaining torque transmission capability
Solution Approach 2:
The patent implements a nested configuration where the flex spline with teeth is positioned within the annular gear, and the wave generator is positioned within the flex spline. This nested arrangement allows multiple gear components to occupy overlapping radial spaces, reducing the overall axial length and moment of inertia while preserving the compound gear ratio functionality
2Force
If axially adjacent gears are used in compound harmonic drives, then the drive can achieve high torque output, but the rotating inertia increases which reduces system response
Solution Approach 1:
The nested arrangement of the flex spline within the annular gear and the wave generator within the flex spline creates a compact configuration that minimizes the radial and axial dimensions of rotating components. This reduces the moment of inertia of the rotating assembly, enabling faster acceleration and improved system response while maintaining high torque output capability
3Force
If axially adjacent gears are used in compound harmonic drives, then the drive can achieve high torque output, but the manufacturing difficulty increases
Solution Approach 1:
By changing from axial to radial gear arrangement, the patent simplifies the manufacturing process. The radial configuration allows for more straightforward machining of gear teeth and easier assembly of components, as parts can be accessed from the radial direction rather than requiring complex axial stacking and alignment procedures
4Device complexity
If a compact design with radially adjacent gears is used, then the rotating inertia is reduced and manufacturing is simplified, but the drive length must be optimized
Solution Approach 1:
The nested configuration places the flex spline inside the annular gear and the wave generator inside the flex spline, creating a concentric arrangement that minimizes both axial and radial dimensions. This nesting strategy achieves compactness in multiple dimensions simultaneously, reducing the overall drive length while maintaining the necessary gear ratios and torque transmission paths
Data Source
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AI summary
Disclosed is a compound harmonic drive including: an inner ring gear (110a) including a first set of gear teeth (120a); a flex spline (130) including a flex spline inner ring (140a) and a flex spline outer ring (140b), the flex spline inner ring forms a second set of gear teeth (120b) that engage the first set of gear teeth and the flex spline outer ring forms a third set of gear teeth (120c); an outer ring gear (110b) including a fourth set of gear teeth (120d) that are engaged by the third set of gear teeth; and a wave generator (150) disposed between the flex spline inner ring and the flex spline outer ring, wherein the gear system rotates about an axis and each set of gear teeth is axially aligned with each other and radially offset from each other about the axis.