Arc-Profile Speed Reduction Mechanism for Higher Gear Ratios
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Solution Overview
Problem
Existing speed reduction mechanisms, such as those described in Patent Document 1, face limitations in increasing the reduction ratio without increasing the body size, particularly due to the use of involute gears which restrict the number of teeth on the helical gear and driven side helical gear.
Innovation Solution
The proposed speed reduction mechanism incorporates a first gear with a spiral engagement projected part and a second gear with multiple engagement recessed parts, allowing for an arc-shaped projected/recessed engaging structure. This design enables an increase in the number of teeth on the second gear while maintaining a single tooth on the first gear, thereby enhancing the reduction ratio without enlarging the mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of teeth on the driven side helical gear is increased to increase the reduction ratio, then the reduction ratio is improved, but the teeth become arranged closely with vertical and flat engaging surfaces causing interference with the helical gear teeth
Solution Approach 1:
The invention applies curvature to the engaging surfaces of the gear teeth. Specifically, the helical gear teeth are formed with an arc-shaped engaging surface having a curvature center at a position different from the gear center, and the driven side gear teeth are formed with a corresponding arc-shaped engaging surface. This curved geometry allows for increased number of teeth on the driven side gear without causing interference, while maintaining reliable engagement and achieving higher reduction ratios.
2Ease of manufacture
If involute gears are used for the helical gear and driven side helical gear, then the manufacturing is simplified, but the reduction ratio cannot be further increased without increasing the body size
Solution Approach 1:
The invention changes the geometric parameters of the gear teeth from conventional involute profiles to arc-shaped profiles with specific curvature radii. The helical gear teeth have an arc-shaped engaging surface with a curvature center at a position different from the gear center, and the driven side gear teeth have corresponding arc-shaped surfaces. This parameter change enables higher reduction ratios within the same body size while maintaining manufacturability through defined geometric relationships.
3Power
If the number of teeth difference between helical gear and driven side helical gear is increased, then the reduction ratio is improved, but the adjacent teeth on driven side helical gear are arranged close causing interference
Solution Approach 1:
By implementing arc-shaped engaging surfaces on both the helical gear teeth and driven side gear teeth with properly positioned curvature centers, the invention enables closer arrangement of adjacent teeth on the driven side gear without interference. This allows increasing the number of teeth difference between gears to achieve higher reduction ratios while maintaining compact body dimensions.
Data Source
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AI summary
Provided are a speed reduction mechanism comprising interlocking gears capable of further increasing a reduction ratio, and a motor equipped with the speed reduction mechanism. In the present invention, one spiral-shaped engagement projection part 31c is provided to a pinion gear 31, a plurality of engagement recess parts 32d to which the engagement projection part 31c engages are provided to a helical gear 32, the engagement projection part 31c and the engagement recess parts 32d are both formed such that the cross-sectional shapes thereof along a direction perpendicular to the axial direction of the pinion gear 31 are arc-shaped, and the shape of oblique teeth 32c and the shape of the engagement recess parts 32d are determined on the basis of the shape of the engagement projection part 31c provided to a spiral-shaped tooth 31b.