One-Way Damper for Window Covering Speed Control
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Solution Overview
Problem
Existing pull cord devices for window coverings lack a braking effect when lowering the base rail, leading to potentially dangerous or damaging fast downward movement, especially when the combined weight of the base rail and slats exceeds the restoring force of the coil spring.
Innovation Solution
A pull cord device incorporating a spring driving unit, braking unit, and one-way damper unit, featuring a unidirectional clutch and damping liquid, which slows down the lowering process by engaging the clutching bodies in shallow grooves, allowing controlled and safer operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pull cord device relies only on the coil spring restoring force to control base rail movement, then the device structure is simple, but the downward moving speed becomes too fast causing safety hazards
Solution Approach 1:
The patent introduces a braking unit as an intermediary component between the coil spring and the base rail. This braking unit includes a braking member that can contact the cord spool to provide braking force, acting as a mediator to control the downward speed of the base rail without requiring complete structural redesign
Solution Approach 2:
The patent implements dynamic control by making the braking member movable relative to the cord spool. The braking member can be positioned at different locations along the cord spool's rotation path, allowing the braking force to be dynamically adjusted based on the base rail's position and speed, thereby controlling the downward movement speed
2Reliability
If the pull cord device adds a braking unit to control lowering speed, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent merges the braking unit with the existing container structure. The braking member is disposed within the container and integrates with the cord spool assembly, combining multiple functions (braking, cord winding, and base rail control) into a single integrated unit rather than adding separate independent components
Solution Approach 2:
The braking member is designed to automatically engage and disengage based on the base rail's movement state. When the base rail descends, the braking member naturally contacts the cord spool to provide braking force, and when the base rail is stationary or ascending, the braking member automatically disengages, eliminating the need for complex control mechanisms
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 provides a controlled and safer lowering mechanism by slowing down the base rail movement, enhancing safety and preventing injuries or damage by maintaining a stable and manageable speed.
Implementation Method 1
The damping liquid fills the gap between the housing and the unidirectional clutch
Implementation Method 2
a spring motor that biases the cord spool to rotate in a cord-winding direction
Implementation Method 3
a unidirectional clutch... that allows rotation in one direction while restraining rotation in the opposite direction
Data Source
AI summary
A one-way damper unit of a pull cord device includes a unidirectional clutch that is disposed in a housing to form a liquid-filled gap therewith and that includes: a casing formed with deep and shallow groove portions; a main shaft having an insert segment extending into the casing and a connecting segment extending outwardly of the casing for connecting to a driven wheel; and a clutching member including a clutching body that extends into the groove and that has a cross-sectional dimension shorter than a distance between the insert segment and the deep groove portion, and longer than a distance between the insert segment and the shallow groove portion.