Flexible External Gear Mesh Position Optimization
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Solution Overview
Problem
Existing gear systems in robots experience reduced durability due to high load stress on external teeth, leading to lower durability and potential defects such as cracking or chipping, especially when the center position of the wave generator is positioned within a specific range that decreases the mesh between external and internal teeth.
Innovation Solution
A gearing system with an internal gear, flexible external gear, and a wave generator that adjusts the mesh position between the gears, where the ratio of L1 to L (distance from the external teeth end to the ball center) is between 0.30 and 0.50, optimizing the mesh amount and dispersing load stress, thereby reducing maximum load stress on the external gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the center position of the wave generator is set within a half of the face width of the external teeth from the open end, then the mesh between external teeth and internal teeth is maintained, but the amount of mesh decreases and load stress on external teeth increases
Solution Approach 1:
The patent applies parameter changes by optimizing the positional parameter L1 (distance from open end to wave generator center) to be within 0.05W to 0.40W of the face width W. This parameter optimization simultaneously maintains adequate mesh engagement between external and internal teeth while increasing the amount of mesh to reduce load stress on external teeth, thereby resolving the contradiction between mesh maintenance and stress reduction
2Strength
If the amount of mesh between external teeth and internal teeth is increased, then load stress on external teeth is reduced, but the mesh position stability may be compromised
Solution Approach 1:
The patent establishes an optimal parameter range for L1 (0.05W to 0.40W of face width W) that balances two competing requirements: increasing mesh amount to distribute load stress and maintaining mesh position stability. This parameter optimization ensures that the wave generator is positioned to engage sufficient teeth for stress distribution while maintaining stable mesh engagement, resolving the contradiction between stress reduction and stability
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 optimized gearing system extends the life of the external gear by reducing load stress and improving reliability, while maintaining high torque capacity and transmission efficiency, preventing defects like cracking or chipping.
Implementation Method 1
a wave generator including a bearing having an outer ring in contact with the inner circumferential surface, an inner ring, and balls intervening between the outer ring and the inner ring, and moving a mesh position between the internal gear and the external gear about the rotation axis
Implementation Method 2
a flexible cup-shaped external gear member placed inside of the member, and a wave generator that bends the cup-shaped external gear member in a radial direction and partially meshes external teeth with internal teeth of the annular internal gear member
Data Source
AI summary
A gearing includes an internal gear, an external gear including external teeth placed around a rotation axis and meshing with the internal gear, a barrel part adjacent to the external teeth along the rotation axis, and an inner circumferential surface on an inner surface of the external teeth, and having flexibility and relatively rotating about the rotation axis to the internal gear, and a wave generator including a bearing having an outer ring in contact with the inner circumferential surface, an inner ring, and balls intervening between the outer ring and the inner ring, and moving a mesh position between the internal gear and the external gear about the rotation axis.