Variable-Force Coil Spring for Smooth Blind Upward Folding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional coil springs in window blinds often face issues with inconsistent elastically restoring forces, leading to non-smooth upward folding or malfunction, due to insufficient force at the lowermost position or excessive force causing rebound.
Innovation Solution
A variable-force coil spring with specific sections that gradually decrease and maintain elastically restoring force, ensuring smooth operation by balancing force requirements as the window blind is opened and closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coil spring is designed with constant torque throughout its length, then the structure is simple, but the elastically restoring force is too small at the lowermost position to resist friction, causing non-smooth upward folding
Solution Approach 1:
The coil spring is divided into multiple sections (first section, second section, third section) along its length, where each section has different torque characteristics. The first section has larger torque for initial lifting, the second section provides gradual force reduction, and the third section maintains appropriate force at the lowermost position, resolving the contradiction between operational smoothness and structural simplicity.
Solution Approach 2:
Different portions of the coil spring are given different local properties (torque values) according to the force requirements at different positions. The spring has larger torque in the upper portions and smaller torque in the lower portions, creating a non-uniform torque distribution that enables smooth upward folding while maintaining reasonable complexity.
2Ease of operation
If the coil spring is designed with varying torque to provide sufficient force at the lowermost position, then upward folding becomes smooth, but the elastically restoring force may become too large, causing rebound
Solution Approach 1:
The coil spring is segmented into three distinct sections with progressively different torque characteristics. The first section provides high torque for initial lifting, the second section gradually reduces torque to prevent excessive force, and the third section maintains appropriately low torque at the lowermost position to avoid rebound, thus achieving both smooth operation and position stability.
Solution Approach 2:
The coil spring design implements dynamic torque variation along its length, where the torque is not constant but changes progressively from the upper portions to the lower portions. This dynamic torque distribution allows the spring to adapt its force output to the specific operational requirements at different positions, preventing both insufficient force and excessive force conditions.
3Adaptability or versatility
If the coil spring provides large elastically restoring force, then the bottom rail can be stopped at any position, but the force is too large at the lowermost position, causing rebound similar to constant-force spring
Solution Approach 1:
The coil spring is divided into multiple torque sections, with the third section specifically designed to provide appropriately reduced torque at the lowermost position. This segmentation allows the spring to maintain high adaptability for position stopping throughout the range of motion while eliminating the harmful rebound effect that would occur with constant or uniformly high force.
Solution Approach 2:
The torque parameter of the coil spring changes progressively along its length, transitioning from high torque in the upper sections to lower torque in the third section. This parameter variation enables the spring to provide sufficient stopping force at intermediate positions while reducing force at the lowermost position to prevent rebound, achieving both adaptability and harm elimination.
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
Enables smooth and convenient upward folding of window blinds by maintaining consistent or slightly ascending restoring force, allowing the blind to be stopped at any position and facilitating easy upward folding.
Implementation Method 1
a coil spring (10) wound on the coil spring winding wheels (44), wherein the coil spring (10) is provided at different parts thereof with different torque
Data Source
AI summary
A variable-force coil spring includes a central hole and a band coiled from the central hole outward. The band includes an inner end located in the central hole, an outer end, and an outer end section from the outer end to a first length, a first force descending section generating gradually descending elastically restoring force from the first length to a second length, a second force descending section generating gradually descending elastically restoring force from the second length to a third length, and a force maintaining section generating maintained elastically restoring force from the third length to a fourth length, which are successively arranged from the outer end toward the inner end in order. The present invention further provides a pulling cord control device including a variable-force coil spring. The present invention is applicable to a window blind to make it convenient and easy to be upward folded smoothly.