Inductive Position Sensor With Dual-Coil Welding Switch Control
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Solution Overview
Problem
Conventional welding control systems using potentiometers and switches suffer from inefficiencies, including wasted potentiometer range, continuous output issues, and mechanical tolerance stack-ups, leading to reliability and cost concerns.
Innovation Solution
The use of inductive sensors with two coils having different spacing regions, which generate a linear flux density gradient, allowing for precise control of welding output and mitigating common-mode errors through measurement circuitry that recognizes and adjusts for positional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional potentiometers and switches are used for welding control, then the system can provide on/off switching and output level control, but the system suffers from mechanical tolerance stack-ups, wasted potentiometer range, and continuous output issues that reduce reliability
Solution Approach 1:
The patent replaces mechanical potentiometers and snap switches with an inductive sensing system using coils and a conductive target. The measurement circuitry detects changes in inductance as the target moves through different positions, providing both switch function (when target enters/exits coil regions) and magnitude control (proportional to target position) without mechanical wear or tolerance stack-ups
Solution Approach 2:
The patent introduces a conductive target as an intermediary element that moves in response to user input (foot pedal or finger-tip control) and interacts with the inductive coils to translate mechanical displacement into electrical signals for both switching and proportional control functions
2Measurement precision
If a single coil is used for position sensing, then the device complexity is reduced, but the system becomes susceptible to common-mode interference and cannot accurately distinguish position changes from distance changes
Solution Approach 1:
The patent divides the sensing function into two separate coils with different spatial configurations (different spacings between turns). Each coil independently measures inductance changes, and the measurement circuitry processes both signals to distinguish position changes from distance changes, eliminating common-mode interference
Solution Approach 2:
The patent creates different local sensing characteristics in different regions of the coil assembly. The first coil has a different spacing pattern than the second coil, creating distinct inductance response profiles that allow the system to differentiate between target position and target distance through comparative measurement
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 a cost-effective and reliable switching and control mechanism, reducing susceptibility to common-mode interference and allowing for efficient on/off switching and power magnitude control in welding applications.
Implementation Method 1
inductive sensors with two coils having different spacing regions, which generate a linear flux density gradient
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A sensor which includes inductive coils and an inductance to digital converter. The output of the sensor may be used to replace the functions of a switch and a potentiometer to initiate and control various outputs in welding-type systems and applications.