Adjustable Friction Limiting Block for Venetian Blind Cord Resistance
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Solution Overview
Problem
Conventional cord-resistance adjusting devices for venetian blinds require different restoring forces to accommodate varying window sizes and weights, making them inconvenient to standardize and mass-produce.
Innovation Solution
A cord-resistance adjusting device with a casing unit, spring driving unit, cord reels, and limiting blocks that allow adjustable frictional resistance by positioning limiting blocks along the cord-exit path, enabling adjustment of the resisting force to balance the blind's weight and desired height without external force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different restoring forces are provided for different window sizes and weights, then the device can accommodate various venetian blind configurations, but the device becomes difficult to standardize and mass produce
Solution Approach 1:
The patent applies parameter changes by modifying the frictional resistance through adjustable limiting blocks rather than changing the entire spring mechanism. The limiting blocks can be positioned at different locations along the cord-exit path to adjust the frictional resistance, thereby adapting the restoring force to different blind weights while keeping the main spring mechanism standardized.
Solution Approach 2:
The patent introduces dynamic adjustability through movable limiting blocks that can be repositioned along the cord-exit path. This dynamic adjustment mechanism allows the frictional resistance to be changed based on the specific application requirements, enabling a single standardized device to serve multiple purposes without requiring custom spring forces for each application.
2Adaptability or versatility
If frictional resistance is adjusted by positioning limiting blocks along the cord-exit path, then the restoring force can be adapted to different blind weights, but the device structure becomes more complex
Solution Approach 1:
The patent segments the cord-exit path into multiple positions where limiting blocks can be placed. Instead of using a continuously variable mechanism, the path is divided into discrete segments with limiting blocks positioned at specific locations. This segmentation provides adjustable frictional resistance while maintaining a relatively simple structure that can be easily manufactured and assembled.
Solution Approach 2:
The limiting blocks serve as intermediary elements between the cord and the housing. These blocks mediate the frictional resistance by contacting the cord at different positions along the exit path. This intermediary approach allows for simple adjustment of the restoring force without requiring complex mechanisms, as the limiting blocks are straightforward components that can be easily positioned and fixed.
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
Facilitates standardization of the restoring force and components for venetian blinds of different dimensions by allowing adjustable frictional resistance, ensuring the blind can be maintained at any desired height without external force application.
Implementation Method 1
the first cord-exit hole is provided with a cord-exit path consecutively passing through the inner limiting column, the at least one limiting block and the outer limiting column, whereby the respective lift cord frictionally contacts the at least one limiting block when moving from the inner limiting column to the outer limiting column along the cord-exit path
Implementation Method 2
The scroll spring 822 is mainly wound around the take-up spool 824 when no forces are applied thereto
Implementation Method 3
a restoring force of the scroll spring 822 balances the weight of the lower beam and the slats
Data Source
AI summary
A cord-resistance adjusting device for a venetian blind includes limiting blocks disposed in a casing unit containing a scroll spring and cord reels. Each of two side casing parts of the casing unit has inner and outer limiting columns mounted thereinside. Each limiting block is movably disposed in the respective side casing part between the inner and outer limiting columns. A lift cord bends around and frictionally contacts the respective limiting block when moving from the inner limiting column to the outer limiting column.