Self-Retracting Extension Limiting Device for Variable Distance
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Solution Overview
Problem
Existing rigging devices face challenges in accommodating varying distances between objects, such as floating docks, where slack in stabilizing cables can become entangled or cause uneven restoring forces, leading to inefficiencies and potential damage.
Innovation Solution
A self-retracting extension limiting device with overlapping and self-contained elements that provides a staged restoring force, minimizing slack and maintaining alignment, using tension springs and apex blocks to connect cables, ensuring a weak initial force that increases significantly when the limit of travel is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cable is used to connect two objects with variable distance, then the cable can accommodate distance variations, but slack in the cable becomes entangled or causes uneven restoring forces
Solution Approach 1:
The patent employs a dynamic spring mechanism that automatically adjusts its tension based on the distance between objects. The spring transitions from a relaxed state with minimal force to a tensioned state with significant restoring force, dynamically adapting to accommodate distance variations while preventing cable slack and entanglement.
Solution Approach 2:
The spring's physical state changes from compressed/relaxed to extended/tensioned as the distance between objects increases. This parameter change in the spring's mechanical state allows the system to provide appropriate restoring force at different extension points, solving the slack control problem while maintaining distance adaptability.
2Reliability
If a spring is added to create restoring force, then slack is taken out of the cable, but the device complexity increases
Solution Approach 1:
The patent merges the spring mechanism directly with the cable assembly, creating an integrated unit where the spring is positioned within the cable's path. This combination eliminates the need for separate slack control devices while maintaining the restoring force function, thus reducing overall device complexity.
Solution Approach 2:
The spring mechanism is self-regulating and automatically provides the necessary restoring force without requiring external control systems or additional components. The spring's inherent elastic properties enable it to self-adjust and maintain cable tension, simplifying the overall device structure while ensuring reliable slack control.
3Force
If a retracting drum with spring is used, then the restoring force can be controlled, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the complex retracting drum mechanism and replaces it with a simpler spring-cable assembly. By removing the drum component entirely and using a direct spring-cable configuration, the design achieves restoring force control through the spring's elastic properties alone, significantly simplifying manufacturing while maintaining force control capability.
Solution Approach 2:
The spring mechanism uses simple, inexpensive elastic materials that can be easily manufactured and replaced if needed. This approach replaces complex mechanical assemblies with affordable spring components, making the device easier to manufacture and maintain while still providing effective restoring force control.
4Reliability
If the check cable is made taut to prevent slack, then entanglement is reduced, but the restoring force becomes too strong over the entire range of motion
Solution Approach 1:
The spring provides a dynamic restoring force that is minimal when the cable is slightly extended and increases progressively as the cable approaches its full extension. This dynamic force adjustment prevents entanglement by keeping the cable taut only when necessary, while avoiding excessive force during normal operation.
Solution Approach 2:
The spring's restoring force parameter changes based on its extension state. At small extensions, the force is weak and allows natural motion; as extension increases toward the limit, the force strengthens to prevent over-extension and entanglement. This parameter change resolves the contradiction between preventing entanglement and avoiding excessive force.
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 device effectively manages tidal variations and maintains alignment, reducing wear and entanglement by providing a controlled and staged restoring force, ensuring the stability of connected objects across varying distances.
Implementation Method 1
spring 16 takes the slack out of the cable by creating slack portion 20... spring 16 will expand and slack portion 20 will become more horizontal... the check cable is preferably made of a material having a much higher linear extension coefficient than spring 16
Implementation Method 2
When all the slack is removed from slack portion 20 the check cable will draw taut. The check cable is preferably made of a material having a much higher linear extension coefficient than spring 16. Thus, as the blocks move away from each other, there will be a first range of distance where the force tending to pull the blocks together (a 'restoring force') grows linearly. Then, when the check cable grows taut, the restoring force tending to pull the blocks together will suddenly grow much greater.
Data Source
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AI summary
A self-retracting extension limiting device. It is designed to be attached between a first object and a second object, where the distance between the first and second objects is variable. The device exerts a restoring force tending to draw the two objects together. A first, relatively weak restoring force is exerted over a range of distance. Then, when the objects have been separated to a defined limit of travel, the device exerts a much greater restoring force. The invention includes overlapping and self-contained elements so that unwanted slack is minimized.