Lace Spool Fastening Mechanism With Over-Tightening Torque Limit
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Solution Overview
Problem
Existing fastening mechanisms for securing articles with laces are prone to loosening due to external forces or vibrations, and can cause lace breakage or damage from excessive tension, with inadequate space for lace reception leading to exposure risks.
Innovation Solution
A fastening device featuring a case unit with a spool, engaging teeth, and a torque unit that includes torque portions to prevent over-tightening by prohibiting spool rotation when excessive force is applied, using mechanisms like friction, deformation, or engagement with depressions to stabilize the lace tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple spring-based fastening mechanism is used, then the structure is simple and easy to manufacture, but the lace is easily released due to vibrations or external force
Solution Approach 1:
The fastening mechanism is divided into distinct functional components: a pawl arm with pawl teeth for engagement, a ratchet wheel with ratchet teeth for one-way locking, and a spring for providing tension. This segmentation allows each component to perform its specific function reliably while maintaining overall structural simplicity and ease of manufacture.
2Ease of operation
If a rotating buckle mechanism is used to tighten the lace, then the lace can be received inside the buckle and tension adjusted, but the lace may break or the article may be damaged due to excessive tension
Solution Approach 1:
The pawl-ratchet mechanism provides mechanical feedback that prevents over-tensioning. When the lace reaches its maximum safe tension, the pawl arm cannot further engage the ratchet teeth, automatically stopping the tightening process. This feedback mechanism ensures the lace receives adequate tension without risking breakage or damage to the article.
3Device complexity
If the fastening mechanism uses only spring restoring force, then the structure is simple, but the lace is easily released due to lack of positive locking
Solution Approach 1:
The invention merges two different locking principles into one unified mechanism: the spring provides continuous restoring force for automatic engagement, while the pawl-ratchet system provides positive mechanical locking. This combination achieves both simplicity and high reliability, preventing lace release under vibration or external force while maintaining an relatively simple device structure.
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
Prevents over-tightening of laces, ensuring secure fastening by preventing spool rotation when excessive force is applied, thereby avoiding lace breakage and damage, while providing a controlled tensioning mechanism.
Implementation Method 1
as a force born by the at least one torque portion exceeds a threshold, the at least one torque portion is deformed
Implementation Method 2
a friction force prohibits the spool from rotating in the releasing direction
Data Source
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AI summary
A fastening device includes a case unit including an inner space, a spool received within the inner space and configured for a lace to be wound thereabout, an engaging unit disposed above the spool along an axis, a torque unit disposed above the engaging unit along the axis and including at least one torque portion, and a knob covering the case unit. As a rotation of the knob in a tensioning direction causes the torque unit to drive the engaging unit for allowing the knob to drive the spool, the spool is rotated in the tensioning direction to tension the lace, and as a force born by the at least one torque portion exceeds a threshold, the spool is not rotated in the tensioning direction.