Three-Convex Harmonic Reducer for Higher Transmission Precision
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Solution Overview
Problem
Existing harmonic speed reducers suffer from poor transmission stability and low transmission accuracy due to large unit area load and significant gear pitch and accumulated pitch errors resulting from only two tooth misalignment motions during a wave generator's rotation.
Innovation Solution
A triple harmonic speed reducer design featuring a flexible inner gear with a three-convex cam structure and a rigid circular spline, allowing for three misalignment motions, which reduces gear pitch and accumulated pitch errors, and increases the meshing contact surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional two-convex cam structure is used in the wave generator, then the structure is simple, but the transmission accuracy is low due to large gear pitch and accumulated pitch errors
Solution Approach 1:
The cam structure is segmented into three convex portions instead of the traditional two, creating multiple misalignment motion cycles during one wave generator rotation. This segmentation increases the number of meshing contact points between the flexible inner gear and rigid outer gear, thereby reducing gear pitch errors and accumulated pitch errors to improve transmission accuracy.
Solution Approach 2:
The invention transitions from a two-convex to a three-convex cam structure, adding an additional dimension of misalignment motion. This dimensional change creates three distinct misalignment cycles per rotation, increasing the meshing contact surface area and reducing unit area load, which directly improves transmission accuracy by minimizing gear pitch errors.
2Reliability
If the meshing contact surface between teeth is small, then the structure is compact, but the unit area load is large resulting in poor transmission stability
Solution Approach 1:
The meshing contact is segmented into three distinct contact zones corresponding to the three convex portions of the cam. This segmentation distributes the load across three separate meshing regions during one rotation, increasing the total meshing contact surface area and reducing the unit area load on each contact point, thereby improving transmission stability.
Solution Approach 2:
The three-convex cam structure ensures continuous meshing contact throughout the rotation cycle, with three overlapping contact zones providing uninterrupted load distribution. This continuous action maintains stable transmission by preventing load concentration and ensuring smooth power transfer across the gear interface.
3Manufacturing precision
If only two tooth misalignment motions occur per rotation, then the structure is simple, but the gear pitch error and accumulated pitch error are large
Solution Approach 1:
The cam is segmented into three convex portions that create three distinct misalignment motion cycles per rotation. This segmentation increases the frequency of tooth engagement and disengagement events, reducing the cumulative pitch error by distributing the misalignment corrections across three cycles instead of two, thereby improving position precision.
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
This design enhances position and rotation precision, stability, and carrying capacity, resulting in smoother and more stable operation with higher precision and reduced unit area load.
Implementation Method 1
a flexible bearing is annularly arranged between an outer ring peripheral surface of the cam and an inner ring peripheral surface of the flexible inner gear
Implementation Method 2
the flexible inner gear is forced to deform elastically and become elliptical
Data Source
AI summary
Disclosed is a triple harmonic speed reducer, which enables a flexible inner gear to generate three tooth misalignment motions after a wave generator rotates for one circle, so that the harmonic speed reducer has higher position precision and rotation precision, more stable transmission, and more stable operation. The triple harmonic speed reducer includes a wave generator, a flexspline and a rigid circular spline, wherein the flexspline includes a flexible inner gear and an output part, the wave generator is arranged in an inner installation cavity of the flexible inner gear, the wave generator includes an input shaft end and a cam, wherein a flexible bearing is annularly arranged between an outer ring peripheral surface of the cam and an inner ring peripheral surface of the flexible inner gear, the cam of the wave generator is specifically of a three-convex structure.