Plastic Helical Gear 3D Tooth Modification
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Solution Overview
Problem
Conventional plastic helical gears with crowning techniques do not sufficiently reduce rotation transmission errors caused by misalignment of gear shafts, leading to inaccuracies in power transmission.
Innovation Solution
A plastic helical gear with a three-dimensional tooth surface modification that combines a tooth top modification surface and an arc crowning surface, gradually reducing tooth thickness from the tooth top to the root along the entire tooth width and height, effectively distributing tooth contact and improving alignment robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crowning is applied to plastic helical gears, then tooth contact is concentrated on the middle of tooth width, but rotation transmission error caused by misalignment of gear shafts is not sufficiently reduced
Solution Approach 1:
The patent transitions from conventional two-dimensional crowning (in the tooth width direction only) to three-dimensional tooth surface modification that incorporates both the tooth width direction and the tooth height direction. This dimensional expansion creates a more comprehensive contact zone that accommodates misalignment in multiple directions, thereby improving rotation transmission accuracy while maintaining manufacturing precision.
Solution Approach 2:
The patent applies different modification characteristics to different regions of the tooth surface. The tooth top modification surface specifically addresses the tooth top region to reduce transmission error, while the arc crowning surface addresses the tooth width distribution. This localized quality enhancement allows each region to contribute optimally to reducing rotation transmission error caused by misalignment.
2Manufacturing precision
If tooth shape modification is applied to reduce rotation transmission error, then transmission accuracy improves, but device complexity increases due to combined surface modification
Solution Approach 1:
The patent merges the tooth top modification surface and the arc crowning surface into a unified three-dimensional modification section. By combining these two modification features into a single integrated structure rather than applying them as separate operations, the patent reduces overall device complexity while achieving the dual benefits of reduced transmission error and improved transmission accuracy.
Data Source
AI summary
A plastic helical gear has a three-dimensional tooth surface modification section on a tooth surface of each of involute-shaped teeth. The three-dimensional tooth surface modification section is a combined surface of a tooth top modification surface and an arc crowning surface. The tooth top modification surface is reduced in tooth thickness from a position between a tooth top and a tooth root toward the tooth top. The arc crowning surface is reduced in tooth thickness from a position between one end in the tooth width direction and the other end in the tooth width direction toward both ends in the tooth width direction. A line extending from an intersection point P0 between the starting position of the tooth top modification surface and the apex position of the arc crowning surface to the tooth root is aligned with a line on the tooth surface of the involute-shaped tooth.