Strain Wave Gearing Backlash Elimination via Corrected Tooth Profile
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Solution Overview
Problem
Strain wave gearing experiences engagement backlash due to underlapping tooth engagement, which leads to increased startup torque and assembly difficulties, and existing solutions require preload or load to eliminate backlash.
Innovation Solution
Elastically deformable external teeth are used to engage with internal teeth in an overlapping state, with a corrected tooth profile to prevent interference, allowing for backlash minimization or elimination without preload, and the external teeth deform in a manner that reduces startup torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gears are designed to engage in an underlapped state to avoid interference, then assembly is facilitated and startup torque is reduced, but engagement backlash increases
Solution Approach 1:
The invention changes the tooth profile parameters by applying correction values (dx, dy) to the standard involute tooth profile. This parameter modification allows the teeth to engage in an overlapping state without interference, eliminating backlash while maintaining assembly ease. The corrected tooth profile enables the external teeth to elastically deform and fit into the internal teeth spaces even when engagement PCDs overlap.
Solution Approach 2:
The invention utilizes the elastic deformation capability of the externally toothed gear to dynamically adapt the tooth thickness during engagement. The external teeth are designed to elastically deform in the direction of tooth thickness increase and decrease, allowing them to engage with internal teeth in an overlapping state without causing interference or excessive startup torque.
2Manufacturing precision
If external teeth are made elastically deformable to eliminate backlash in underlapped engagement, then engagement precision improves, but startup torque increases rapidly due to overlapping engagement
Solution Approach 1:
By correcting the tooth profile parameters, the invention reduces the overlap amount between engaging teeth. The correction values (dx, dy) are specifically designed to minimize interference while maintaining the overlapping engagement state, thereby reducing startup torque. This parameter optimization allows the external teeth to elastically deform without causing excessive force requirements during startup.
3Manufacturing precision
If tooth profile is corrected to prevent interference in overlapping engagement, then tooth surface load increases, but engagement backlash is eliminated
Solution Approach 1:
The tooth profile correction is designed to minimize the overlap amount while still achieving backlash elimination. By optimizing the correction values (dx, dy), the invention reduces tooth surface load compared to conventional overlapping engagement designs. The corrected profile ensures that the external teeth can elastically deform into the internal teeth spaces without excessive interference or load concentration.
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 solution effectively minimizes or eliminates tooth engagement backlash, prevents rapid startup torque increases, and simplifies assembly by allowing smooth engagement without preload, while maintaining load torque capacity.
Implementation Method 1
external teeth of a flexible externally toothed gear are elastically deformable in a direction in which the tooth thickness of the external teeth increases and decreases
Data Source
AI summary
In a strain wave gearing, external teeth of a flexible externally toothed gear are elastically deformable in a direction in which the tooth thickness of the external teeth decreases. Engagement between internal teeth of a first and a second rigid internally toothed gears and the external teeth is set in an overlapping state in which the external teeth elastically deform and engage in a state in which no gap is present. The tooth profile of the internal teeth is a corrected tooth profile so that no interference occurs between a tooth top portion of the internal teeth and a dedendum portion of the external teeth when the teeth are engaged in the overlapping state. A strain wave gearing capable of minimizing or eliminating tooth engagement backlash is realized.