Dual Flex Spline Actuator for Balanced Strain Wave Gearing
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Solution Overview
Problem
Existing strain wave gears face challenges in achieving balanced load distribution, minimizing twisting and asymmetrical forces, and improving efficiency while maintaining a compact size and lightweight design.
Innovation Solution
The actuator incorporates a pair of flex splines oriented in opposite directions, earthed to earth annuli, which are connected to a stable support, and a wave generator that elastically deforms the flex splines to engage with a circular spline, utilizing pre-stage gearing and epicyclic gear trains for efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flex spline is used in the strain wave gear, then the structure is simpler, but the load distribution becomes unbalanced and twisting forces increase
Solution Approach 1:
The single flex spline is divided into two separate flex splines that are earthed to different earth annuli. This segmentation allows each flex spline to carry a portion of the load independently, achieving balanced load distribution and reducing twisting forces while maintaining structural integrity through the dual-earth-annulus configuration.
2Stability of the object's composition
If the flex spline is made more rigid to reduce deformation, then the structural stability improves, but the elastic deformation capability required for gear engagement is reduced
Solution Approach 1:
The flex spline is designed with non-uniform thickness, being thinner at the tooth roots and thicker at the base. This local quality variation allows the tooth regions to deform elastically for gear engagement while the thicker base regions maintain structural stability and resist excessive deformation, effectively balancing both requirements within a single component.
3Manufacturing precision
If the number of teeth in the flex spline and circular spline are made closer, then the gear ratio precision improves, but the number of teeth in mesh decreases reducing load capacity
Solution Approach 1:
Two flex splines are used in parallel, each engaging with the circular spline. This merging of two engagement paths increases the total number of teeth in mesh across both flex splines, thereby increasing load capacity while maintaining the precise tooth count relationship required for accurate gear ratios.
4Force
If the actuator size is increased to accommodate more components, then the load capacity and efficiency improve, but the compactness and weight increase
Solution Approach 1:
The dual flex spline configuration is nested within a compact housing that accommodates both earth annuli and the circular spline in a space-efficient arrangement. The wave generator is positioned centrally to drive both flex splines simultaneously, creating a nested structure that maximizes load capacity within a minimized footprint and weight.
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 achieves balanced load distribution, reduced tooth mesh skewing, higher efficiency, and a compact, lightweight actuator with improved reliability and lower cost, suitable for applications requiring high gear ratios and reconfigurable gear ratios.
Implementation Method 1
The wave generator is configured to be activated by rotation of the input shaft, and the wave generator is configured to elastically deform both of the pair of flex splines when the input shaft activates the wave generator
Data Source
AI summary
An actuator includes an input shaft, a wave generator, a pair of flex splines, a pair of earth annuli, and an output annulus. Each of the pair of flex splines are earthed to an earth annulus. The output annulus comprises a circular spline. The wave generator is configured to be activated by rotation of the input shaft, and the wave generator is configured to elastically deform both of the pair of flex splines when the input shaft activates the wave generator.