Single Cable Descent Control Using Eddy Current Braking
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Solution Overview
Problem
Existing descent control devices for structures along cables are constrained by the need for multiple cables and idler sheaves, limiting the angle and positioning of the cable, and requiring significant site preparation and material usage.
Innovation Solution
A single cable descent control device using a pair of rotors with conductive frames and magnets mounted on a central axle, inducing eddy currents to create a braking force, allowing for precise and controlled descent with reduced mechanical wear and overheating, and eliminating the need for multiple cables and idler sheaves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple cables and idler sheaves are used to support descent control devices, then braking capability and control precision are improved, but device complexity and material usage increase
Solution Approach 1:
The patent replaces traditional mechanical friction brakes with an electromagnetic braking system. The electromagnetic brake uses magnetic fields to apply braking force to the cable, eliminating the need for complex mechanical friction-based braking mechanisms. This substitution provides more reliable and controllable braking while reducing mechanical wear and structural complexity.
Solution Approach 2:
The patent employs variable speed control by adjusting electromagnetic parameters (current, voltage, magnetic field strength) to control the descent rate. By changing electromagnetic parameters dynamically, the system achieves precise speed regulation without requiring multiple cables or complex mechanical arrangements, thus improving reliability while reducing device complexity.
2Reliability
If multiple cables are used to support the enclosure, then descent control reliability is improved, but cable positioning flexibility and site preparation requirements worsen
Solution Approach 1:
The electromagnetic braking system replaces mechanical friction-based control on multiple cables with a single cable system. The electromagnetic brake can independently control the descent on one cable, providing reliable control without requiring multiple cables to be positioned precisely, thus improving adaptability while maintaining reliability.
3Force
If idler sheaves are used to impart tension to the cable, then cable tension control is improved, but the size and rigidity requirements of side walls increase
Solution Approach 1:
The electromagnetic brake directly applies braking force to the cable without requiring mechanical sheaves to transmit and distribute tension through the enclosure structure. This eliminates the need for large, rigid side walls to support multiple sheaves, reducing structural requirements while maintaining effective cable tension control.
4Force
If mechanical friction brakes are used, then braking force is achieved, but mechanical wear and overheating risk increase
Solution Approach 1:
The patent replaces mechanical friction brakes with an electromagnetic braking system that uses magnetic fields to generate braking force. The electromagnetic brake applies magnetic resistance to the moving cable without physical contact, eliminating mechanical wear and reducing overheating risks associated with friction-based braking, while still providing effective braking 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
This solution provides greater flexibility in cable positioning, reduces material and labor costs, and allows for controlled descent with minimal mechanical stress, enabling steeper paths and more versatile load configurations while maintaining safety and precision.
Implementation Method 1
rotation of the rotor relative to the conductors creates relative motion between the magnets' magnetic field and the conductor and induces eddy currents in the conductor that oppose the magnetic field and create a rotational braking force
Implementation Method 2
rotation of the rotor relative to the conductors creates relative motion between the magnets' magnetic field and the conductor and induces eddy currents in the conductor
Data Source
AI summary
A single cable descent control device comprises a pair of rotors with corresponding frames of conductive material mounted on a common central axle on either side of a drive pulley. The pulley is adapted to sit above a single descent cable. An enclosure is suspended from the device. Disposed along at least one surface of each of the rotors or of the corresponding frames or both, is a series of magnets such that rotation of the rotors relative to the frames induces eddy currents that oppose the magnetic field and create a rotational braking force providing precise and controllable descent of the enclosure with little or no mechanical wear or risk of overheating. In this configuration, constraints on the size of the enclosure are dispensed with, as are corresponding limitations on the positioning and angle of descent of the cable. Further, significant labor and material savings in manufacturing the enclosure may be obtained from the resulting simplicity of design. The device may be used in numerous other applications, including without limitation, permitting controlled descent of gondolas or chairs from ski lift operations when normal lift operation is temporarily precluded.