String Length Adjuster With Integrated Shaft Coupling Assembly
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Solution Overview
Problem
Conventional string length adjusting devices require multiple components, including coupling members and springs, leading to increased manufacturing costs, complexity, and difficulty in assembly and maintenance, with high failure rates and poor quality uniformity.
Innovation Solution
A simplified string length adjusting device composed of only three components - a fixing housing, a rotating housing, and a winding drum - that are press-fitted together without the need for coupling members or springs, utilizing a shaft and sawteeth interaction for operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If coupling members (bolts, screws) and springs are used to couple components, then the device can maintain structural integrity and provide elastic force, but manufacturing costs increase and device complexity increases
Solution Approach 1:
The patent combines multiple functions into the housing structure itself. The housing serves as both the structural container and the coupling mechanism, eliminating the need for separate coupling members and springs. This merging of functions reduces component count while maintaining structural integrity through the integrated design of the housing that provides both containment and elastic coupling capabilities.
Solution Approach 2:
The patent extracts and removes the coupling members (bolts, screws) and springs from the device assembly. By taking out these separate components and eliminating their functions through integrated housing design, the device achieves simpler construction with fewer parts while maintaining the necessary structural and elastic functions through the housing itself.
2Ease of manufacture
If coupling members are used to couple components, then the device can be assembled, but assemblability deteriorates due to difficulty in maintaining uniform fastening torque
Solution Approach 1:
The patent removes coupling members from the assembly process entirely. By extracting the bolts, screws, and springs that require torque control, the device achieves easier assembly without the need to maintain uniform fastening torque. The integrated housing design allows for simpler assembly operations that do not require precision torque control.
3Force
If springs are used as essential components, then the device can provide elastic force for operation, but failure rate increases due to spring deformation or separation
Solution Approach 1:
The patent extracts and eliminates springs from the device. By removing the spring component entirely and replacing its elastic force function with an integrated housing design, the device eliminates the failure modes associated with springs such as deformation, separation, and fatigue. The housing structure provides the necessary elastic response without relying on separate spring components that can fail.
4Adaptability or versatility
If multiple components are used in the device, then the device can perform required functions, but production costs increase
Solution Approach 1:
The patent merges multiple components into an integrated housing structure. By combining the functions of multiple separate parts into a single housing component, the device maintains its functional capabilities while reducing the total number of parts that need to be manufactured, inventoried, and assembled. This merging directly reduces production costs through simplified manufacturing and assembly processes.
Solution Approach 2:
The housing is designed to perform multiple functions simultaneously - serving as the structural container, the coupling mechanism, and the source of elastic force. This multi-functionality eliminates the need for separate specialized components, reducing the overall component count and associated production costs while maintaining all required device functions.
Data Source
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AI summary
Provided is a device for adjusting the length of a string. The device has an improved structure that lowers the unit cost and failure rate of a product by reducing the number of components and improves the assemblability, consistency in quality, operational stability, and convenience of future servicing of the product. In the device, a shaft and a shaft coupling part of a winding drum are simply coupled without a separate coupling member as a protruding portion formed on the shaft becomes caught in a catching portion formed on the shaft coupling part. Accordingly, coupling is enhanced, and thus replacement and maintenance of the device is easier.