Elastic Harmonic Gear Wheel Flange for Stress-Relieved Deformation
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Solution Overview
Problem
Existing harmonic drives with elastic gear wheels face damage due to high tensions at transition points when connected to large chain wheels, limiting their service life and torque transmission capability.
Innovation Solution
The design incorporates a flange with strategically placed through holes that reduce stiffness and allow greater deformation, relieving load and tension spikes, while maintaining structural integrity through directional reinforcement and attachment holes, allowing for a more elastic gear wheel with enhanced material flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flange is reinforced to maintain structural integrity, then strength is improved, but deformation capability deteriorates leading to permanent damage at transition points
Solution Approach 1:
The flange is designed with non-uniform thickness, being thicker at the outer edge for strength and thinner at the inner region near attachment holes for deformation capability. This local variation in geometric properties allows different regions to fulfill different functional requirements simultaneously.
Solution Approach 2:
The flange is divided into distinct regions with different thicknesses and structural characteristics. The outer region provides structural support while the inner region accommodates deformation, creating a segmented structure that resolves the contradiction between strength and deformability.
2Stability of the object's composition
If the flange is made thinner to increase flexibility, then deformation capability is improved, but strength deteriorates leading to potential breaks under heavy loads
Solution Approach 1:
The flange thickness is optimized locally: thinner at the inner region where deformation is needed and thicker at the outer edge where structural strength is required. This local differentiation resolves the contradiction between flexibility and strength.
Solution Approach 2:
The geometric parameter of flange thickness is varied continuously or stepwise across the flange radius, transitioning from thinner inner regions to thicker outer regions. This parameter change allows the flange to exhibit both flexibility and strength in different locations.
3Ease of manufacture
If attachment holes are provided for securing the flange, then ease of attachment is improved, but deformation capability deteriorates due to stress concentration at hole edges
Solution Approach 1:
Attachment holes are strategically positioned in regions where they cause minimal disruption to the overall deformation pattern. The flange geometry is designed so that hole locations coincide with areas where stress concentration has less impact on the critical deformation zones.
Solution Approach 2:
The attachment holes serve as intermediaries that connect the flange to mounting surfaces while the surrounding flange structure acts as a stress-distributing medium that mitigates the harmful stress concentration effects of the holes.
4Duration of action of stationary object
If the gear wheel is made more elastic to increase deformation, then service life is improved, but torque transmission capability deteriorates
Solution Approach 1:
The elastic properties of the gear wheel are optimized by controlling the thickness distribution and material properties to achieve an optimal balance between deformation capability and torque transmission. The gear wheel is designed to deform within elastic limits that extend service life while maintaining sufficient stiffness for torque transfer.
Solution Approach 2:
The gear wheel is designed to undergo controlled partial deformation that is sufficient to reduce stress concentrations and extend service life, but not so excessive as to compromise torque transmission capability. The deformation is kept within optimal bounds.
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 reduces material fatigue and tension spikes, enabling higher precision rotational movements and increased service life by allowing greater deformation without weakening the gear wheel in less deformed regions, making it suitable for high-torque applications like internal combustion engine compression ratio adjustment.
Implementation Method 1
The holes provided only for reducing the thickness, in comparison, allow for a significantly greater deformation of the material, thus reducing the tension spikes and counteracting material fatigue
Implementation Method 2
The attachment holes are at a spacing to the outer edge of the flange. The attachment holes may be circular, and their diameter is adapted to the attachment screws
Implementation Method 3
The toothing of the cylindrical section may be an outer toothing, which meshes with an inner toothing on the housing of the gearing
Data Source
AI summary
An elastic gear wheel for a harmonic drive has a cylinder portion with tooth, and a flange which is integrally designed with the cylinder portion. The flange has recesses for fastening, and through-apertures for fastening.