RF Welding Device Impedance Control for Flexible Medical Tubes
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Solution Overview
Problem
Portable cordless radiofrequency welding apparatuses for flexible tubes face inefficiencies due to impedance changes during welding, leading to reduced energy efficiency and limited autonomy, especially when trying to achieve more than 500 welds while maintaining a compact and lightweight design.
Innovation Solution
The device incorporates a clamping member with adjustable electrodes, a radio-frequency generator, and a power converter featuring series-connected inductors and an electric current flow control element to maintain constant impedance during welding, ensuring optimal energy transfer and efficiency by short-circuiting inductors during resonant frequency detuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If portable cordless welding apparatuses are designed to be compact and lightweight, then portability is improved, but energy efficiency deteriorates due to impedance changes during welding
Solution Approach 1:
The patent applies dynamics by making the inductor configuration adjustable during operation. The system dynamically switches between different inductor connections (series/parallel) based on real-time impedance detection, allowing the apparatus to adapt to changing welding conditions while maintaining optimal energy efficiency in a compact design
Solution Approach 2:
The patent changes electrical parameters (inductor connection configuration) to maintain constant impedance despite electrode distance variations. By switching between series and parallel inductor connections, the system adjusts the total inductance to compensate for impedance changes, thereby maintaining energy efficiency without increasing apparatus weight
2Adaptability or versatility
If the distance between electrodes changes during welding, then welding adaptability is improved, but impedance stability deteriorates, adversely affecting weld quality and energy efficiency
Solution Approach 1:
The patent implements feedback by continuously detecting the impedance of the welding circuit and using this information to control the switching between inductor configurations. The microprocessor monitors impedance changes and triggers appropriate switch operations to maintain constant total inductance, thereby stabilizing impedance despite electrode distance variations
Solution Approach 2:
The system dynamically adjusts the inductor connection configuration in response to real-time impedance measurements. By switching between series and parallel connections based on detected impedance levels, the system maintains stable total inductance and constant impedance throughout the welding process, enabling adaptability without sacrificing stability
3Duration of action of moving object
If maximum energy efficiency is achieved to ensure autonomy greater than five hundred welds, then welding autonomy is improved, but device complexity increases due to impedance control mechanisms
Solution Approach 1:
The patent segments the inductor into multiple sections that can be independently connected in series or parallel configurations. This segmentation allows the system to achieve multiple impedance states using the same physical components, extending welding autonomy without proportionally increasing device complexity
Solution Approach 2:
The same inductor components serve multiple functions by being reconfigurable between series and parallel connections. The inductor assembly can provide different total inductance values depending on the connection configuration, allowing a single component set to handle multiple impedance requirements, thereby extending autonomy without linearly increasing complexity
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 enhances energy efficiency, allowing the welding device to perform over 500 welds on a single charge with minimal weight and size, maintaining consistent impedance and resonant frequency, thus improving the overall performance and autonomy of the portable welding apparatus.
Implementation Method 1
a high-frequency (HF) signal is generated between these two electrodes, causing dielectric loss and a rise in tube temperature
Implementation Method 2
said power converter comprising at least two inductors connected in series with the first and second electrode of the welding member
Data Source
AI summary
A device for welding a flexible tube by radio frequency includes:a clamping member having a welding head formed by a first electrode and a second electrode,a power source configured to supply electrical power to the welding device, anda welding member having a radiofrequency generator and a radiofrequency power converter, the first and second electrodes, the power source, the radio-frequency generator and the power converter forming between them an electrical circuit having an impedance, the power converter including at least two inductors connected in series with the first and second electrode of the welding member and an electrical current flow control element configured to cut off the flow of the electrical current in one of the inductors so as to maintain the impedance of the electrical circuit constant during welding.