Cord Tension Control Using Threaded Spool Stops
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Solution Overview
Problem
Retractable coverings for architectural openings, such as top down/bottom up coverings, often experience entanglement issues with lift cords around their spools, leading to malfunctioning due to the cords becoming entangled when one movable rail is moved past another.
Innovation Solution
A cord tension control system utilizing pairs of adjacent threaded rods that rotate in unison with wrap spools, featuring abutment nuts that engage at preselected positions to prevent entanglement by ensuring that movement of one rail past another is avoided at any desired relative location of the rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lift cords are wrapped around spools to raise and lower movable rails, then the covering can be extended and retracted, but the lift cords become entangled when one movable rail is moved past another
Solution Approach 1:
A guide member is introduced as an intermediary component between the lift cord and the spool. The guide member includes a groove that directs the lift cord along a predetermined path, preventing the cord from becoming entangled on the spool when rails move past each other. The cord is guided through the groove and exits at a controlled location, maintaining proper cord routing throughout the full range of motion.
Solution Approach 2:
The guide member is pre-configured with a groove that establishes the correct cord path before any rail movement occurs. This preliminary arrangement of the cord through the guide member's groove prevents entanglement from occurring in the first place, rather than attempting to correct it after it happens.
2Adaptability or versatility
If multiple movable rails are used for top down/bottom up coverage, then positioning flexibility is improved, but cord entanglement risk increases
Solution Approach 1:
Each movable rail is equipped with its own guide member that acts as an intermediary to control the specific lift cord associated with that rail. The guide members independently manage each cord's path, allowing multiple rails to move freely while preventing cross-entanglement between cords even when rails pass each other in various sequences.
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 system effectively prevents entanglement of lift cords, ensuring smooth operation and maintaining the functionality of the covering by controlling the rotation of the threaded shafts and associated abutment nuts, thus avoiding the malfunctioning caused by cord entanglement.
Implementation Method 1
a threaded shaft (92) rotatably mounted in the headrail (46) for unison rotation with the wrap spool (86) and having an abutment nut (120) thereon that is translatable along the length of the threaded shaft (92) as it rotates
Data Source
AI summary
Cord tensioning systems are provided for top down/bottom up coverings to prevent entanglement of lift cords about associated wrap spools by correlating rotation of the wrap spools with translating threaded nuts mounted on threaded shafts rotating in unison with the wrap spools whereby abutment of nuts associated with lift spools prevent over movement of rails associated with the spools and thus entanglement of the lift cords associated therewith.