Sprocket Carrier Fastening for Quick Sprocket Changes
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Solution Overview
Problem
Current sprocket replacement methods in chain drive power transmission systems, particularly in racing karts, are inefficient and time-consuming, often resulting in lost nuts and requiring disengagement of bolts, which can lead to delays during pit stops.
Innovation Solution
A sprocket assembly with a securing arrangement featuring bolts and nuts that utilize an interference fit between the knurled shank portion of the bolt and the sprocket carrier, allowing for quick release and reinstallation without disengaging the nuts, facilitating faster sprocket changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional bolts and nuts are used to secure the sprocket, then the sprocket can be firmly secured to the carrier, but the replacement process becomes time-consuming and requires disengagement of nuts
Solution Approach 1:
The bolt is segmented into distinct functional portions: a knurled shank portion for interference fit engagement with the carrier, and a threaded shank portion for nut engagement. This segmentation allows the bolt to provide both secure anchoring and easy removal capabilities, resolving the contradiction between firm securing and quick replacement.
Solution Approach 2:
Instead of requiring the nut to be disengaged for removal, the design inverts the removal mechanism: the knurled shank portion's interference fit allows the bolt to be pulled directly out of the carrier without touching the nut. This inversion eliminates the time-consuming nut disengagement step while maintaining secure securing during operation.
2Reliability
If traditional bolts and nuts are used to secure the sprocket, then the connection is secure, but nuts may be lost during the replacement process
Solution Approach 1:
The extraction principle is applied by removing the nut from the removal process entirely. The knurled shank portion provides a direct extraction mechanism where the bolt itself is pulled out of the carrier through interference fit engagement, eliminating the need to handle or disengage nuts during replacement, thus preventing lost nuts.
Solution Approach 2:
The bolt's knurled shank portion serves a dual function: it provides secure anchoring in the carrier through interference fit, and simultaneously serves as its own removal tool. The knurled surface allows direct gripping and extraction of the bolt without requiring separate nuts or additional components, making the system self-sufficient and preventing component loss.
3Productivity
If the bolt is retained by interference fit, then quick release is enabled, but the bolt must fit precisely in the aperture
Solution Approach 1:
Different portions of the bolt are given different local qualities: the knurled shank portion has a rough, high-friction surface for strong interference fit engagement, while the threaded shank portion has precise threading for nut engagement. This local quality differentiation allows the critical interference fit portion to tolerate minor dimensional variations while maintaining secure retention, reducing the overall precision requirement.
Solution Approach 2:
The knurled surface changes the friction parameter at the interference fit interface, creating a high-friction zone that enhances retention even with moderate dimensional tolerances. This parameter change allows the bolt to maintain secure engagement without requiring extremely tight manufacturing precision, balancing quick release capability with manufacturing feasibility.
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 solution significantly reduces the time required for sprocket changes, enhancing racing efficiency by allowing for quicker pit stops and minimizing the risk of lost components.
Implementation Method 1
the bolt is retained within the sprocket carrier by an interference fit between the knurled shank portion of the bolt and the sprocket carrier
Data Source
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AI summary
A sprocket assembly (101) comprises a sprocket carrier (102), a sprocket (103), and a plurality of fixing devices (104) for use in securing the sprocket ( 103) to the sprocket carrier (102). Each fixing device (104) comprises a bolt (601) and a nut (602), the nut (602) engageable with a threaded shank portion (604) of the bolt (601), and the bolt (601) insertable through a fixing aperture (401) of the sprocket carrier (102) into a fitted condition in which the bolt (601) is retained within the sprocket carrier (102) by an interference fit between a knurled shank portion (605) of the bolt (601) and the sprocket carrier (102). A sprocket (103), a sprocket carrier (102), and a sprocket protector (106) for use within the sprocket assembly ( 101).