Friction Ring Cable Energy Absorber for Lifeline Anchors
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Solution Overview
Problem
Existing energy absorbing devices for anchoring lifelines are bulky, prone to deformation under low stresses, and lack a compact, economical, and safe design to effectively absorb significant forces during falls.
Innovation Solution
An energy absorbing device with a casing, a wound cable, a friction ring, and abutment means that allows relative movement and energy absorption only under high tensile forces, preventing untimely triggering and maintaining a compact structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a piston and cylindrical housing are used to absorb energy, then energy absorption capacity is improved, but device volume increases
Solution Approach 1:
The patent extracts the essential energy absorption function from the complex piston-cylinder mechanism and implements it through a simpler cable-based system with friction elements. The cable is wound around a drum and passes through friction rings that can slide along the cable, allowing energy absorption through friction and cable deformation rather than requiring a bulky piston stroke mechanism.
Solution Approach 2:
The patent replaces the mechanical piston-cylinder system with a cable-friction-drum system. Instead of using a piston moving within a cylinder to absorb energy, the invention uses a cable wound around a drum with friction rings that slide along the cable during energy absorption, substituting a compact mechanical system for a bulkier conventional one.
2Loss of energy
If elastic components are used for damping, then shock absorption is improved, but device reliability deteriorates due to deformation under slight stress
Solution Approach 1:
The patent changes the operational parameters of the damping system by using a cable with high tensile strength and friction rings with predetermined sliding thresholds. The cable and friction system remain rigid under normal loads but allow controlled slippage only when the tensile force exceeds a specific threshold, preventing unwanted deformation under slight stress while maintaining shock absorption capability.
Solution Approach 2:
The patent introduces dynamic behavior through the friction rings that can transition from a locked state (preventing cable movement) to a sliding state (allowing energy absorption). The friction rings remain stationary during normal operation but become mobile when the tensile force on the cable exceeds the friction threshold, providing conditional energy absorption only when needed.
3Volume of moving object
If a compact design is implemented, then device volume is reduced, but energy absorption stroke is limited
Solution Approach 1:
The patent applies nesting by winding the cable around a central drum in a compact spiral pattern. The cable is arranged in concentric loops around the drum, allowing a long effective cable length (and thus long absorption stroke) to be contained within a small radial space. The friction rings slide along this nested cable arrangement, maintaining the compact structure while enabling sufficient stroke for energy absorption.
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 absorbs energy during falls without deforming under normal conditions, ensuring safety and a significant absorption stroke while maintaining a non-bulky design, with visual indicators for stress visualization.
Implementation Method 1
a friction ring (10) mounted on the first cable section (5) to exert a clamping force on the latter
Implementation Method 2
The friction generated by such a displacement of the first cable segment absorbs at least part of the energy due to the impact
Implementation Method 3
stop means (11) disposed in the housing along a part of the first cable section (5) extending between the connection means (7) and the friction ring (10), and against which the friction ring (10) is intended to bear
Data Source
Figure 1~2
Figure 3~5b
Figure 4a~7
AI summary
The device (2) has a cable portion wound inside a casing (4), and a friction ring mounted on the cable portion in order to exert clamping force on the cable portion. A stop unit i.e. stop ring, placed in the casing along a part of the cable portion extends between a connection unit (7) and the friction ring. The force is preset to authorize relative displacement of the cable portion with respect to the friction ring when the friction ring is supported against the stop unit, and a tensile force greater than a predetermined value is exerted on the connection unit.