String Fastening Device with Integrated Clutch and Pawl Mechanism
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Solution Overview
Problem
Conventional string fastening devices are complex, difficult to assemble, and have exposed parts that can tangle with foreign objects, particularly when installed on shoes, due to their numerous components and protruding shifting levers.
Innovation Solution
A simplified string fastening device with a clutch mechanism that allows the knob to be rotated in one direction to tighten the string, featuring a tubular base, axially movable pawls, a toothed reel, and a positioning ring, which eliminates the need for a gear set and external shifting lever, enabling easy operation by pulling the knob upward to loosen the string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional fastening device with ratchet device, gear set and shifting lever is used, then the string can be securely reeled and loosened, but the device has too many parts making it difficult and time-consuming to assemble
Solution Approach 1:
The patent merges the ratchet wheel and reel into a single integrated component with teeth directly formed on the reel body. The pawl is integrated with the knob assembly, eliminating the need for separate gear sets and shifting levers. This consolidation reduces the total part count and simplifies assembly while maintaining the one-way rotation control function.
Solution Approach 2:
The reel serves multiple functions: it acts as both the spool for winding the string and the ratchet wheel with teeth for one-way rotation control. The knob assembly combines the release mechanism, pawl actuation, and rotation control in a single component, providing universal functionality that eliminates the need for separate specialized parts.
2Ease of operation
If a conventional fastening device with exposed shifting lever is used, then the string can be loosened manually, but the exposed shifting lever might tangle foreign objects
Solution Approach 1:
The patent removes the external shifting lever from the device structure. The release mechanism is extracted and integrated into the knob assembly itself, where the knob's axial movement directly actuates the pawl without requiring an external lever. This eliminates the protruding element that could catch foreign objects while preserving the manual release function.
Solution Approach 2:
Instead of using an external lever that pushes the pawl to release, the invention inverts the mechanism by having the knob's axial movement directly lift the pawl through integrated cam surfaces or inclined planes. The release action is achieved by pulling the knob rather than pushing an external lever, reversing the traditional operation direction and eliminating external protrusions.
3Volume of moving object
If a compact fastening device is used, then the space is limited, but it is difficult to accommodate all necessary components
Solution Approach 1:
The patent employs nested positioning where the pawl is housed within the knob assembly, the reel is positioned within the tubular base, and the positioning ring is nested on the reel to limit axial movement. This nested arrangement allows multiple components to occupy overlapping or concentric spaces, maximizing space utilization within the compact tubular structure while accommodating all necessary functional elements.
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
The solution provides a compact, easy-to-assemble device with reduced risk of tangling and improved usability by allowing the string to be easily loosened without external protrusions, enhancing operational efficiency and assembly convenience.
Implementation Method 1
A plurality of second teeth are defined in the underside of the knob and engaged with the inclined surfaces of the pawls such that the knob is rotated in one direction and stopped in the other direction by the pawls
Implementation Method 2
The pawl 66 is pivotably connected to the cover 62 and is cooperated with a torsion spring 661 so that the pawl 66 is normally biased by the torsion spring 661 toward the ratchet wheel 71
Data Source
AI summary
A string fastening device includes a reel on which a string is reeled thereon and a toothed ring is connected to the reel. A knob has a shaft inserted into a tube extending from the base of the device and the reel is rotatably mounted on the tube. The knob has first teeth in an underside thereof and the first teeth are engaged with the toothed ring so that the reel is driven by rotation of the knob to tighten the ring. The knob can be pulled away from the reel to disengage the first teeth from the toothed ring so that the string can be loosened. The knob includes second teeth and the base has two pawls which limit the knob to rotate in one direction to drive the reel.