Wave Generator Roller Inclination for Angular Transmission Precision
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Solution Overview
Problem
Conventional roller-type wave generators experience deflection issues when flexing cup-shaped or silk-hat-shaped flexible externally toothed gears into ellipsoidal shapes, leading to decreased precision in angular transmission due to misalignment between rollers and the inner peripheral surface of the gear.
Innovation Solution
The rollers are designed with their center axis lines parallel to the gear's center axis and their outer peripheral surfaces inclined to match the inner peripheral surface incline, preventing deflection and ensuring precise contact without angular transmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If rollers are arranged on the major axis of the flexible externally toothed gear, then the gear can be flexed into an ellipsoidal shape, but deflection occurs on the contacting region of the inner peripheral surface leading to decreased angular transmission precision
Solution Approach 1:
The roller outer peripheral surfaces are given different inclinations matched to the local incline of the inner peripheral surface at each roller's contact position. This local adaptation of roller geometry eliminates deflection at each contact point while maintaining the overall ellipsoidal flexing of the gear, thereby resolving the contradiction between achieving the required shape transformation and maintaining angular transmission precision
Solution Approach 2:
The inclination angle of the roller outer peripheral surface is changed as a parameter to match the local incline of the gear's inner peripheral surface. By adjusting this geometric parameter of the roller based on its position, the invention eliminates deflection while maintaining the ellipsoidal flexing action, thus resolving the precision issue
2Device complexity
If rollers with circular outer peripheral surfaces are used to flex the gear, then the structure is simple, but deflection occurs in the tooth-trace direction contacting the inner peripheral surface
Solution Approach 1:
Instead of using uniform circular rollers throughout, the invention applies local quality by giving each roller an outer peripheral surface with a specific inclination matched to its contact position on the gear. This localized geometric adaptation maintains structural simplicity while eliminating the deflection that would compromise angular transmission reliability
Solution Approach 2:
The invention introduces asymmetry in the roller geometry by inclining the outer peripheral surface at different angles for rollers at different positions. This asymmetric design, where each roller is tailored to its specific location, prevents deflection in the tooth-trace direction while maintaining overall system simplicity
Data Source
AI summary
An externally toothed portion of a cup-shaped flexible externally toothed gear of a wave gear device is flexed into an ellipsoidal shape by a six-roller-type wave generator. A region of an inner peripheral surface of the ellipsoidally flexed externally toothed portion that is positioned on a major axis of the ellipsoidal shape is maximally inclined. First rollers of the wave generator are arranged so that the incline is identical to the incline of the region of the inner peripheral surface. A circular outer peripheral surface of the first rollers can be brought into contact with the region of the inner peripheral surface in an external-tooth tooth-trace direction without deflection; therefore, the angular transmission precision of the wave gear device can be improved.