Dual-Type Strain Wave Gearing for Balanced Tooth Meshing
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Solution Overview
Problem
In strain wave gearings, the differing numbers of first and second external teeth lead to inadequate meshing states, resulting in reduced load capacity, torque transmission, and wear resistance, along with potential interference and imbalance in tooth bottom fatigue strength, as well as increased fluctuation in bearing-ball load distribution, which can degrade the service life of wave bearings.
Innovation Solution
The dual-type strain wave gearing configures first and second external teeth with specific tooth depth and pressure angle relationships, ensuring they flex equally and mesh satisfactorily with internal teeth, with the first teeth having greater depth and pressure angle than the second teeth, and thicker rim walls to maintain balance and prevent interference, thereby optimizing meshing states and torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the externally toothed gear has different numbers of first and second external teeth to achieve different speed ratios, then the speed ratio range is improved, but the meshing state becomes inadequate leading to reduced load capacity and torque transmission
Solution Approach 1:
The patent applies local quality by configuring different tooth depths and pressure angles for first and second external teeth. Specifically, the first external teeth have a first tooth depth and first pressure angle, while the second external teeth have a second tooth depth and second pressure angle. This localized differentiation allows each tooth set to be optimized for its specific meshing requirements, maintaining adequate meshing states and load capacity across different speed ratio configurations
Solution Approach 2:
The patent utilizes parameter changes by varying the tooth depth and pressure angle parameters for different external teeth. The first external teeth are configured with specific depth and pressure angle parameters, while the second external teeth have different parameters. This parameter differentiation enables the gear system to achieve multiple speed ratios while maintaining proper meshing conditions and torque transmission capability for each configuration
2Adaptability or versatility
If the externally toothed gear has different numbers of first and second external teeth, then the speed ratio is improved, but interference and imbalance in tooth bottom fatigue strength occur
Solution Approach 1:
The patent applies local quality by configuring different tooth depths and pressure angles for first and second external teeth. Specifically, the first external teeth have a first tooth depth and first pressure angle, while the second external teeth have a second tooth depth and second pressure angle. This localized differentiation allows each tooth set to be optimized for its specific meshing requirements, maintaining adequate meshing states and load capacity across different speed ratio configurations
Solution Approach 2:
The patent utilizes parameter changes by varying the tooth depth and pressure angle parameters for different external teeth. The first external teeth are configured with specific depth and pressure angle parameters, while the second external teeth have different parameters. This parameter differentiation enables the gear system to achieve multiple speed ratios while maintaining proper meshing conditions and torque transmission capability for each configuration
3Reliability
If the wave generator presses the flexible externally toothed gear radially outward to sustain meshing, then the meshing is maintained, but the bearing-ball load distribution fluctuates increasing wave bearing wear and reducing service life
Solution Approach 1:
The patent applies local quality by configuring different tooth depths and pressure angles for first and second external teeth. Specifically, the first external teeth have a first tooth depth and first pressure angle, while the second external teeth have a second tooth depth and second pressure angle. This localized differentiation allows each tooth set to be optimized for its specific meshing requirements, maintaining adequate meshing states and load capacity across different speed ratio configurations
Solution Approach 2:
The patent utilizes parameter changes by varying the tooth depth and pressure angle parameters for different external teeth. The first external teeth are configured with specific depth and pressure angle parameters, while the second external teeth have different parameters. This parameter differentiation enables the gear system to achieve multiple speed ratios while maintaining proper meshing conditions and torque transmission capability for each configuration
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 configuration eliminates insufficiencies and interferences in meshing, enhances load capacity and torque transmission, maintains tooth fatigue strength balance, and minimizes bearing-ball load fluctuations, thereby extending the service life of wave bearings and improving overall performance.
Implementation Method 1
a cylindrical externally toothed gear capable of flexing in a radial direction
Implementation Method 2
two rows of ball bearings fitted to the outer-peripheral surface
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth (7, 8) having different teeth numbers. The first and second external teeth (7, 8) are flexed by a wave generator by the same flexing amount, into an ellipsoidal shape. The tooth depth (h1) of tooth profiles (70) of the first external teeth (7) having a low teeth number is smaller than the tooth depth (h2) of tooth profiles (80) of the second external teeth (8) having a high teeth number. A dual-type strain wave gearing can be achieved with which the first and second external teeth having different teeth numbers can be suitably flexed to form excellent meshing states with respective internally toothed gears.