Sunscreen Cord Tensioning Assembly With Rotation-Limit Stops
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Solution Overview
Problem
Existing tensioning devices for flexible elongate members, such as those in sunscreen assemblies, face issues where rapid movement can lead to slacking due to inertia, causing irregular winding and loss of tensioning function.
Innovation Solution
A restriction device is implemented to limit the maximum relative rotation between the first and second winding members, using cooperating projections or recesses to maintain the elongate member in a taut state, allowing pre-tensioning before assembly and controlling rotation to prevent slacking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first end of the elongate member is moved quickly towards the first winding member during winding, then winding speed is improved, but the inertia of the winding shaft causes the elongate member to slack resulting in irregular winding
Solution Approach 1:
The restriction device applies a preliminary counteracting force to the inertial effect. By providing mechanical stops (projections and recesses) that limit the maximum relative rotation between winding members, the system pre-prevents the elongate member from going slack during rapid winding operations, counteracting the harmful inertial effect before it can cause irregular winding
Solution Approach 2:
The restriction device introduces dynamic control to the tensioning system. The ability of the first and second winding members to rotate relative to each other within limited bounds allows the system to dynamically adapt to rapid movement conditions while maintaining tension, transforming a static tensioning arrangement into a dynamically responsive one
2Productivity
If the first end of the elongate member is moved quickly away from the first winding member during unwinding, then unwinding speed is improved, but the inertia of the second winding member causes the elongate member to slack resulting in loss of tensioning function
Solution Approach 1:
The restriction device applies preliminary counter-action to prevent slacking during rapid unwinding. The mechanical stops limit the relative rotation between winding members, pre-preventing the inertial slacking effect before it occurs, thereby maintaining tensioning function even during high-speed unwinding operations
3Adaptability or versatility
If the maximum relative rotation between first and second winding members is not limited, then the tensioning device can accommodate large movements, but the elongate member will slack during rapid operations due to inertia
Solution Approach 1:
The restriction device creates a dynamically controlled range of motion. By allowing relative rotation within limited bounds defined by the mechanical stops, the system maintains adaptability for normal operations while preventing the excessive rotation that would cause slacking during rapid movements, thus resolving the contradiction between range of motion and reliability
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 ensures the elongate member remains taut during all operations, preventing slacking and maintaining the tensioning device's functionality even under rapid movement conditions.
Implementation Method 1
the first and second winding members are interconnected by a tensioning member striving to cause a relative rotation between the first and second winding members for creating a prestress or tension in the elongate member
Implementation Method 2
a restriction device configured to limit the maximum possible relative rotation between the first and second winding members
Implementation Method 3
the first and second winding members are interconnected by a tensioning member striving to cause a relative rotation between the first and second winding members for creating a prestress or tension in the elongate member
Data Source
AI summary
A tensioning device for tensioning a flexible elongate member, such as a cord, comprises a first winding member which can rotate around an axle for, directly or indirectly, winding and unwinding the elongate member at a first end thereof, and a second winding member which can rotate around said axle for, directly or indirectly, winding and unwinding the elongate member at the second end thereof. The first and second winding members are interconnected by a tensioning member striving to cause a relative rotation between the first and second winding members for creating a prestress or tension in the elongate member. A restriction device is provided for limiting the maximum possible relative rotation between the first and second winding members.