Spoke with Square Cross-Section for Torque Management
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Solution Overview
Problem
Existing spoke designs face issues with deformation and damage during assembly due to strong clamping forces required to prevent rotation and torque-induced twist, which can lead to breakage and corrosion, and do not effectively manage stress concentrations.
Innovation Solution
A spoke with a square cross-section and a rectangular shaft section is designed to allow easy rotation positioning with limited force, distributing torque and stress evenly, reducing drag and the risk of breakage by clamping at the square section and limiting torque to the second end, while the rectangular section enhances tensile stress and reduces shear stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spoke is clamped strongly to prevent rotation during nipple screwing, then rotation prevention is achieved, but the spoke may be damaged or deformed
Solution Approach 1:
The spoke features an asymmetric cross-sectional design with a first section having a different cross-section than a second section. This asymmetry allows the clamp to engage with the larger cross-section for stable positioning and torque application, while the smaller cross-section reduces the clamping force required, preventing damage to the spoke during assembly
Solution Approach 2:
Different sections of the spoke have different cross-sectional properties optimized for different functions. The first section has a larger cross-section for clamping and torque resistance, while the second section has a smaller cross-section for reduced clamping force requirement and stress distribution, creating local quality variations that solve the contradiction
2Ease of operation
If the spoke shaft is allowed to rotate freely during nipple screwing, then no deformation or twist occurs, but the nipple cannot be properly tensioned
Solution Approach 1:
The asymmetric cross-section acts as an intermediary between the clamp and the spoke shaft. It provides a positive engagement surface that prevents rotation during tensioning while distributing forces evenly to avoid deformation, serving as a mediator that enables both rotation prevention and stress management
Solution Approach 2:
The cross-sectional parameters of the spoke are changed along its length, with the first section having different dimensions than the second section. This parameter variation allows optimization for different functional requirements: clamping stability in one region and stress reduction in another
3Strength
If the spoke has a larger cross-section area, then tensile strength is increased, but drag during rotation increases
Solution Approach 1:
The spoke is segmented into different cross-sectional sections along its length. The first section has a larger cross-section for high tensile strength where stress is concentrated, while the second section has a smaller cross-section for reduced drag during rotation, dividing the spoke into functional zones that optimize both strength and energy efficiency
Data Source
Figure 1~5
AI summary
The invention concerns a spoke for coupling a hub to a rim of a wheel comprising a first end (C) for mounting in the hub (7) which first end has a head (6) for holding the spoke in the hub (7), a second end (A) that has a screw thread (1) on which a nipple can be screwed for holding the spoke in the rim and tensioning the spoke and a shaft (B) between the first end (C) and the second end (A). In accordance with the invention between the screw thread (1) and the shaft (B) the spoke has a square cross-section.