Arc-Profile Deceleration Mechanism for High-Ratio Gear Engagement
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Solution Overview
Problem
Existing deceleration mechanisms, such as those described in Patent literature 1, face limitations in increasing the deceleration ratio without enlarging the mechanism, due to the use of involute gears which restrict the number of teeth on the helical gear.
Innovation Solution
The proposed deceleration mechanism employs a first gear with a spiral tooth part and a second gear with inclined tooth parts, featuring engagement projected and recessed parts formed in an arc shape. This design allows for an increased deceleration ratio by varying the number of teeth on the second gear while maintaining one tooth on the first gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of teeth on the driven side helical gear is increased to increase the deceleration ratio, then the deceleration ratio increases, but the adjacent teeth become arranged close to each other and the engagement surface becomes flat, causing interference between teeth and deterioration in engagement state
Solution Approach 1:
The invention applies curvature to the engagement surfaces of the gear teeth. Specifically, the driven side helical gear is designed with a curved engagement surface that maintains proper contact geometry even when the number of teeth is large. This curvature prevents the engagement surface from becoming flat, thereby avoiding tooth interference while achieving high deceleration ratios.
Solution Approach 2:
The invention changes the geometric parameters of the gear teeth, specifically modifying the engagement surface shape from the conventional involute profile to a custom curved profile. This parameter change allows the gear to maintain proper engagement characteristics with a small number of teeth on the driving gear while having many teeth on the driven gear, achieving high deceleration without tooth interference.
2Power
If the difference in the number of teeth between the helical gear having a small gear number and the driven side helical gear is increased to increase the deceleration ratio, then the deceleration ratio increases, but the size of the deceleration mechanism must be increased
Solution Approach 1:
The curved engagement surface design allows for a more compact gear arrangement. By optimizing the curvature radius and engagement geometry, the invention achieves high deceleration ratios within a smaller volume, eliminating the need to increase the overall size of the deceleration mechanism to accommodate larger tooth count differences.
3Reliability
If involute gears are used for the helical gear having a small gear number and the driven side helical gear, then the engagement is reliable, but there is a limit to increasing the deceleration ratio without increasing the size of the deceleration mechanism
Solution Approach 1:
The invention changes the fundamental engagement parameter from the standard involute profile to a custom curved profile optimized for high-ratio deceleration. This parameter change enables the gear to achieve both reliable engagement and high deceleration ratios, overcoming the limitations of conventional involute gears which cannot achieve high deceleration without increasing size.
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
The arc-shaped engagement structure maintains the engagement state between the gears, enabling an increased deceleration ratio without enlarging the mechanism, and allows for a more compact design compared to traditional worm reduction gears.
Implementation Method 1
an engagement projected part arranged on the first tooth part, formed in an arc shape in a direction orthogonal to the axial direction of the first gear, and having a curvature center at a position eccentric from the rotation center of the first gear; an engagement recessed part arranged between the adjacent second tooth parts, formed in an arc shape in a direction orthogonal to the axial direction of the first gear, and engaged with the engagement projected part
Data Source
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Figure 3
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AI summary
A deceleration mechanism is provided with first and second gears, a first tooth part arranged in the first gear and extending spirally in an axial direction of the first gear, an engagement projected part arranged on the first tooth part, second tooth parts arranged on the second gear, and an engagement recessed part arranged between the adjacent second tooth parts. The engagement projected part is formed in an arc shape in a direction orthogonal to the axial direction of the first gear and has a curvature center eccentric from a rotation center of the first gear. The second tooth parts are inclined with respect to the axial direction of the first gear and arranged in a circumferential direction of the second gear. The engagement projected part is formed in an arc-shape in a direction orthogonal to the axial direction of the first gear and engaged with the engagement projected part.