Dual-Type Wave Gear Flexing for Stable Multi-Tooth Meshing
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Solution Overview
Problem
Dual-type strain wave gearing faces challenges in flexing first and second external teeth with different numbers on a shared cylindrical body, leading to inappropriate meshing states and uneven bearing-ball load distribution, affecting wear resistance, tooth rim fatigue, and wave bearing service life.
Innovation Solution
The solution involves setting the radial flexing amounts of first and second external teeth to be larger than their theoretical values, with a coefficient ω between 1.25 and 3, allowing them to mesh suitably with internal teeth and average the bearing-ball load distribution, enhancing wear resistance and tooth bottom fatigue strength, and elongating wave bearing life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If first and second external teeth with different numbers are formed on a shared cylindrical body, then a strain wave gearing with speed ratio less than 50 can be realized, but inappropriate meshing states and uneven bearing-ball load distribution occur
Solution Approach 1:
The patent applies local quality by making the cylindrical body have different radial flexing amounts at different locations. Specifically, the first external teeth are radially flexed by a first amount while the second external teeth are radially flexed by a second amount, allowing each tooth set to achieve appropriate meshing states with their respective internally toothed gears despite being on the same shared body.
2Productivity
If first and second external teeth with different numbers are formed on a shared cylindrical body, then a strain wave gearing with speed ratio less than 50 can be realized, but uneven bearing-ball load distribution occurs
Solution Approach 1:
The patent applies local quality by making the cylindrical body have different radial flexing amounts at different locations. Specifically, the first external teeth are radially flexed by a first amount while the second external teeth are radially flexed by a second amount, allowing each tooth set to achieve appropriate meshing states with their respective internally toothed gears despite being on the same shared body.
3Ease of manufacture
If the cylindrical body is flexed uniformly, then manufacturing is simplified, but meshing states of external teeth with different numbers become inappropriate
Solution Approach 1:
The patent applies local quality by making the cylindrical body have different radial flexing amounts at different locations. Specifically, the first external teeth are radially flexed by a first amount while the second external teeth are radially flexed by a second amount, allowing each tooth set to achieve appropriate meshing states with their respective internally toothed gears despite being on the same shared body.
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 approach enables suitable meshing states for both external teeth, improving wear resistance and tooth bottom fatigue strength, and averaging the bearing-ball load distribution, resulting in a strain wave gearing with a low speed ratio and extended wave bearing service life.
Implementation Method 1
a flexible externally toothed gear in which first external teeth capable of meshing with the first internal teeth and second external teeth capable of meshing with the second internal teeth are formed in the outer-peripheral surface of a radially flexible cylindrical body
Implementation Method 2
a first wave bearing fitted to the outer-peripheral surface, the first wave bearing comprising bearings for supporting the first external teeth; and a second wave bearing fitted to the outer-peripheral surface, the second wave bearing comprising bearings for supporting the second external teeth
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
An externally toothed gear (4) of a dual-type strain wave gearing (1) is provided with first and second external teeth (7, 8) having different teeth numbers, and is flexed into an ellipsoidal shape by a wave generator. When the theoretical values (d1, d2) of the radial flexing amounts at major-axis positions of the first and second external teeth (7, 8) flexed into the ellipsoidal shape are expressed by d1=m1n1 and d2=m2n2 (m1 and m2 represent the modules of the first and second external teeth, and n1 and n2 represent positive integers), the radial flexing amounts (d1a, d2a) of the first and second external teeth (7, 8) flexed by the wave generator (5) satisfy d1a=ωd1 and d2a= ωd2, where 1.25 ≦ω≦ 3. Accordingly, a dual-type strain wave gearing can be achieved with which the first and second external teeth having different numbers can be suitably flexed to form excellent mating states with respective internally toothed gears.