Weightless Medical Traction With Constant-Force Spring Spools
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Solution Overview
Problem
Existing traction devices for medical applications struggle to maintain a constant tractive force during surgical procedures, often requiring repeated adjustments due to slippage or limb stretching, and are cumbersome to assemble and disassemble, posing health and safety risks.
Innovation Solution
A system utilizing constant-force springs mounted on spools, with flexible biasing members and quick-connectors, allowing for adjustable and constant traction force application without gravitational loads, enabling discrete adjustments without repositioning the patient or device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gravity-based traction systems are used, then constant tractive force can be applied, but the system becomes cumbersome and difficult to assemble/disassemble
Solution Approach 1:
The patent replaces the traditional gravity-based mechanical system (weights, pulleys, ropes) with a spring-based elastic mechanical system. The constant-force spring mechanism eliminates the need for gravitational loads while maintaining constant tractive force through the elastic properties of the spring, thereby simplifying the overall system structure and reducing assembly complexity
Solution Approach 2:
The patent extracts and removes the cumbersome gravitational loading components (weights, pulleys, ropes) from the traction system, retaining only the essential force-generating element (constant-force spring). This extraction simplifies the system to its core functional elements while maintaining the desired constant force application capability
2Force
If traditional traction devices are used, then traction force can be applied, but repeated adjustments are needed when limb stretches or slippage occurs
Solution Approach 1:
The constant-force spring mechanism ensures continuous and uninterrupted application of tractive force throughout the surgical procedure. As the limb stretches or repositions, the spring automatically adjusts its length while maintaining constant force, eliminating the need for repeated manual adjustments and ensuring continuous therapeutic action
Solution Approach 2:
The patent employs a dynamic spring-based system that can adapt to changes in limb position and length. The constant-force spring inherently accommodates variations in the distance between attachment points while maintaining constant force, providing a dynamic response to anatomical changes without requiring system reconfiguration
3Ease of operation
If weight bearing members are positioned close to treatment table, then mounting is simplified, but traction effectiveness is reduced
Solution Approach 1:
The patent replaces the gravity-dependent mechanical advantage system with a direct spring-force application system. The constant-force spring generates traction force independently of gravitational orientation, allowing effective force application regardless of the device's position relative to the treatment table, thereby decoupling mounting convenience from traction effectiveness
4Ease of operation
If patient movement is allowed during traction, then patient comfort is improved, but maintaining constant force becomes difficult
Solution Approach 1:
The constant-force spring mechanism is inherently dynamic and automatically adjusts to changes in the distance between attachment points. When the patient moves or the limb repositions, the spring extends or contracts while maintaining constant force through its elastic properties, thereby allowing patient mobility without compromising force constancy
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
Provides a constant traction force that remains stable during repositioning, reduces system weight and size, and eliminates the need for cumbersome assembly, enhancing surgical efficiency and safety.
Implementation Method 1
Each of the spools houses a constant force spring that is secured to an inner circumferential wall of the spool at an outer (in coiled configurations) end, and fixed to a rigid arbor member that is independent from the spool at its inner coil end, thereby imparting a constant load to its respective spool
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A system for translating a constant traction load to an object such as a medical device or a patient includes a plurality of independently rotatable, coaxially aligned spools, each housing a constant force spring fixed at respective ends to the spool and to a rigid member, a plurality of flexible biasing members each coupled on their respective first ends to a spool and at least partially wound around the spool. A plurality of connectors are connected to the respective other ends of the biasing members, which may comprise wire rope. The connectors are configured to quickly couple to and decouple, directly or indirectly, from the object to which the traction load is being delivered. A guide provides a partial path for one or more of the biasing members to the object. A selected load may be applied by coupling one or more of the reversible couplers tensioned by the constant force springs to the object, without use of gravitational loading.