Double-Flexspline Harmonic Reducer With Deformation Limiting
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Solution Overview
Problem
Existing harmonic reducers face challenges with return difference accuracy due to engagement tightness issues between elliptical long shaft teeth and rigid gear teeth, leading to increased production costs and reduced precision life, as well as wear that affects engagement tightness and accuracy.
Innovation Solution
A double-flexspline harmonic reducer with a strong flexspline and a weak flexspline, where the strong flexspline has a flexible thin wall for non-circular elastic deformation, and a deformation stopper limits the deformation of the strong flexspline, allowing for adjustable deformation and improved engagement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the engagement between flexspline and rigid wheel is made tighter to reduce return difference, then transmission precision is improved, but assembly difficulty increases and rotation becomes difficult
Solution Approach 1:
The invention changes the fundamental parameter of the rigid wheel into a flexible component (flexspline), transforming the engagement mechanism from rigid-to-flexible to flexible-to-flexible. This parameter change allows both flexsplines to engage with controlled elastic deformation, achieving tight engagement for precision while maintaining ease of assembly and rotation through elastic compliance.
Solution Approach 2:
The invention introduces a double-flexspline structure where both the inner and outer flexsplines are made of elastic materials with different stiffness characteristics. The outer flexspline has limited elastic deformation capability controlled by a stopper, while the inner flexspline has greater flexibility. This flexible-shell approach enables precise engagement while avoiding the assembly and rotation difficulties associated with overly tight rigid engagements.
2Manufacturing precision
If higher accuracy requirements are imposed on harmonic reducer to improve transmission precision, then return difference is reduced, but production cost increases and material/processing options are limited
Solution Approach 1:
The invention changes the material parameter from rigid to elastic for both flexsplines, fundamentally altering the engagement mechanism. This parameter change allows the system to achieve high transmission precision through controlled elastic deformation rather than relying on extremely tight manufacturing tolerances, thereby reducing production costs and expanding material and processing options.
Solution Approach 2:
By using flexible components instead of rigid components with tight tolerances, the invention achieves high precision through elastic compliance. The outer flexspline's limited deformation (controlled by stopper) and inner flexspline's greater flexibility create a system that tolerates broader manufacturing variations while maintaining precision, thus reducing production costs and enabling use of cheaper materials and processing techniques.
3Manufacturing precision
If the flexspline and rigid wheel are made to accurately engage to improve transmission precision, then return difference is reduced, but precision life is shortened due to wear
Solution Approach 1:
The invention changes the engagement parameter from rigid contact to elastic contact between two flexsplines. This parameter change transforms the wear mechanism from severe rigid-to-rigid contact wear to milder elastic deformation wear, maintaining engagement accuracy over extended periods and thereby extending precision life.
Solution Approach 2:
The double-flexspline structure with elastic materials allows engagement through controlled deformation rather than rigid contact. The outer flexspline's limited elastic deformation and inner flexspline's greater flexibility create a compliant engagement that reduces wear compared to rigid wheel engagement, thus extending the duration during which precision is maintained.
4Manufacturing precision
If a rigid wheel is replaced with a strong flexspline to improve deformation control, then engagement accuracy is enhanced, but structural complexity increases
Solution Approach 1:
The invention replaces the rigid wheel with a strong outer flexspline that has limited elastic deformation capability controlled by a stopper. This flexible shell structure, combined with the inner flexspline, creates a double-flexspline system that enhances engagement accuracy through controlled elastic interaction while managing structural complexity through the stopper mechanism.
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 design enhances the tolerance to machining tolerances, reduces material fatigue, and extends the precision life of the reducer while allowing the use of cheaper materials and processing techniques, achieving high-precision transmission with reduced costs.
Implementation Method 1
the contact part of the strong flexspline and the weak flexspline is subjected to the radial pressure of the weak flexspline to generate a non-circular elastic deformation
Implementation Method 2
the limiting contact surface...is contacted with the annular limiting surface, and the deformation of the strong flexspline is limited due to the contact between the strong flexspline after deformation the deformation stopper
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present application discloses a double-flexspline harmonic reducer, comprising a strong flexspline (3), a weak flexspline (2), a wave generator (1), and a deformation stopper (4) of the strong flexspline; the strong flexspline and the weak flexspline are coaxially fixed axially and radially, the strong flexspline and the weak flexspline are respectively provided with teeth that can engage with each other; the number of teeth of the strong flexspline and the weak flexspline are different; the wave generator is used to make the weak flexspline to undergo non-circular elastic deformation and partially engage with the strong flexspline; the contact part of the strong flexspline and the weak flexspline is subjected to the radial pressure of the weak flexspline to generate a non-circular elastic deformation, a flexible tubular wall of the strong flexspline has a toothless surface, and a limiting contact surface is processed on the toothless surface, and the deformation stopper of the strong flexspline is relatively fixed with the strong flexspline; the deformation stopper of the strong flexspline is processed with an annular limiting surface, and the limiting contact surface, located at the non-circular elastic deformation region where the strong flexspline is subjected to the radial pressure of the weak flexspline, is contacted with the annular limiting surface, and the deformation of the strong flexspline is limited due to the contact between the strong flexspline after deformation the deformation stopper. The double-flexspline harmonic reducer has more tolerant of machining tolerances, and can use parts with lower tolerance requirements to achieve high-precision, small return difference or even zero return difference.