Intrabody Extension Device Using Traction Rod and Magnetic Drive
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Solution Overview
Problem
Existing intracorporeal elongation devices, such as bone lengthening nails and spinal distraction rods, face limitations due to the rod being mounted between moving ends, leading to increased rod length under load, which restricts elongation and requires high torque for operation, making simple power transmission methods impractical.
Innovation Solution
The device design reverses the rod's mounting orientation so it shortens as the device lengthens, with a small diameter rod working in tension, utilizing a neodymium magnet for rotation control and surface treatments to reduce friction, allowing for efficient lengthening with modest torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the rod is mounted between two ends which move apart when the device lengthens, then the device can achieve elongation, but the loaded rod length increases and the rod works in compression, limiting the elongation by buckling height
Solution Approach 1:
The patent inverts the traditional mounting configuration by positioning the rod between two ends that come together when the device extends, rather than between ends that move apart. This inversion transforms the rod's working condition from compression to tension, eliminating buckling limitations and enabling greater elongation lengths.
2Length of moving object
If the rod is mounted between moving ends, then the device can elongate, but the volume devoted to the rod and thread does not contribute to bending solidity
Solution Approach 1:
By inverting the rod mounting configuration, the patent ensures that the rod and thread components work in tension rather than compression. This not only enables greater elongation but also allows the rod volume to contribute more effectively to the overall structural solidity and bending resistance of the device.
3Length of moving object
If the rod is mounted between moving ends, then the device can elongate, but the torque necessary for rotation of the rod is important, limiting the use of simple power transmission means
Solution Approach 1:
The inverted mounting configuration changes the rod's working condition from compression to tension, significantly reducing the torque required for rotation. This enables the use of simple and reliable direct magnetic transmission without amplification means, such as direct magnetic transmission between two permanent magnets.
Solution Approach 2:
The patent employs direct magnetic transmission to replace complex mechanical power transmission systems. By using permanent magnets for direct magnetic coupling, the system eliminates the need for mechanical gears, belts, or other transmission components that would be required to handle high torque loads.
4Volume of moving object
If a small diameter rod is used to reduce volume, then the device becomes more compact, but the rod requires high torque for rotation when working in compression
Solution Approach 1:
By inverting the rod mounting to work in tension rather than compression, the patent enables the use of small diameter rods with minimal torque requirements. The tension working condition eliminates buckling concerns and reduces rotational torque needs, allowing for compact device design.
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 configuration decreases the loaded rod length, enabling greater elongation potential and reducing the required torque, making the device more efficient and practical for use with simpler power transmission methods.
Implementation Method 1
a receiving permanent magnet mounted integral with said rod so that its direction of magnetization is substantially perpendicular to the axis of rotation of said rod and, outside the body, a source of driving magnetic field rotating substantially around the axis of said rod
Data Source
Figure 1~3
AI summary
A device for intrabody extension with screws working in traction. A first elongate section (1) receives a second telescopic section (2). Each of these sections includes means (61), (62) for connection to the body at a first end (11), (21), and is linked to a pin (3) containing at least one threading at a second end (12) and (22). Rotation of the pin (3) controlled by means (4) causes relative movement of the two sections (1) and (2). Thus, the pin (3) is mounted between two ends (12) and (22) which move closer when the device is elongated, and the loaded pin length (7) decreases when the device is elongated and the loaded pin length (7) works only in traction. The device according to the invention is specifically designed for making screws for bone elongation and growth prostheses.