Blind Cord Spool with Longitudinal Ribs for Even Winding
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Solution Overview
Problem
Existing blind cord spool designs face challenges in achieving even winding without overlapping, while maintaining sufficient cord tension and minimizing friction, especially when using conical shapes and smooth surfaces, which can lead to excessive tension and axial transport issues.
Innovation Solution
A cord spool with a cylindrical body featuring longitudinally extending ribs, which provide enhanced circumferential friction to manage cord tension and prevent overlapping, combined with a conical design and a snap-indexed end plug for adjustable cord length, ensuring even winding and reduced axial friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conical spool with smooth surface is used to transport windings axially, then axial friction is reduced and windings are transported smoothly, but cord tension becomes too high and winding control deteriorates
Solution Approach 1:
The spool surface is given different local properties: the axial direction maintains smoothness for low friction, while the circumferential direction has ribs creating high friction zones. This local differentiation allows the spool to simultaneously enable smooth axial transport and maintain adequate cord tension for winding control.
Solution Approach 2:
The invention changes the surface parameter of the spool from uniformly smooth to ribbed with increased circumferential friction. The ribs modify the friction coefficient in the circumferential direction while maintaining low axial friction, thereby adjusting the tension characteristics without sacrificing transport smoothness.
2Reliability
If circumferential threading is used on the spool, then cord tension is maintained and overlapping is prevented, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of circumferential threading throughout, the invention applies ribs only at specific locations on the spool surface. This localized approach maintains winding control where needed while keeping the overall structure simpler and easier to manufacture than full circumferential threading.
Solution Approach 2:
The invention extracts only the essential friction-providing elements (ribs) from the more complex circumferential threading system. The ribs provide the necessary cord tension maintenance and overlapping prevention without requiring the complex threaded structure of prior solutions.
3Power
If a keyed connection between spool and drive shaft is used, then rotational drive is transmitted, but longitudinal space is consumed
Solution Approach 1:
The spool is designed with a hollow cylindrical body that can be mounted over the drive shaft, nesting the spool structure around the drive mechanism. This nested configuration transmits rotational power through the keyed connection while minimizing the axial space occupied by the connection 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 effectively manages cord tension and prevents overlapping, ensuring smooth and even winding of blinds while maintaining low axial friction, thus improving the operational efficiency of blind lifting and lowering mechanisms.
Implementation Method 1
the use of longitudinally extending ribs on the spool solves this problem... provide enhanced circumferential friction to manage cord tension
Implementation Method 2
The decrease in diameter of the spool in the sloping portion ensures the transport of the windings and the even, regular winding of the cord
Data Source
AI summary
A cord spool for winding a lift cord for lifting or lowering a window covering wherein the cord spool includes an elongated general cylindrical body with a large diameter end and a small diameter end and a circumferential outer surface of a given length extending therebetween. The circumferential outer surface having a plurality of generally parallely extending longitudinal ribs. The cord spool can be provided as part of a lifting and lowering mechanism for a blind further including a rotatable drive shaft and at least one lift cord. A support is provided for rotatably supporting the cord spool and the support may be attached to a head rail by means of a separate cord guiding grommet in the head rail. It may also include means for supporting a drive mechanism. The cord spool can be constructed from two halves and may also include an end plug, which can be snap-indexed between relative angular positions to adjust the cord length.