Eddy Current Coil Layout for Tilt-Compensated Linear Displacement

The patent replaces traditional mechanical coil windings with an eddy current-based sensing mechanism. Instead of using large wire coils wound around tubes, the invention uses a sender member that generates a magnetic field and sense coils that detect changes in this field caused by eddy currents in the conductive element. This substitution eliminates the need for complex mechanical coil assemblies while maintaining measurement reliability through electromagnetic field interactions.

The patent changes the fundamental operating parameters of the sensor by transitioning from direct magnetic coupling through large coils to eddy current induction. The sender member operates at specific frequencies to generate magnetic fields that induce eddy currents in the conductive element, and the sense coils detect the modified field. This parameter change allows for smaller, less complex coil structures while achieving reliable position detection through the eddy current effect.

The patent uses asymmetrical positioning of the sender member relative to the sense coils, placing the sender offset from the centerline. This asymmetrical arrangement creates a magnetic field distribution that is sensitive to both position and tilt, allowing the system to detect and compensate for tilt errors. The asymmetry enables the sensing system to distinguish between actual position changes and tilts of the conductive element.

The patent implements feedback through the use of multiple sense coils (first and second sense coils) that provide redundant measurement information. By comparing signals from multiple coils and using the known asymmetrical geometry, the system can calculate tilt angles and compensate for them in the final position measurement. This feedback mechanism corrects tilt-induced errors and maintains measurement precision.

The patent segments the sensor into distinct functional components: a sender member with specific winding patterns and separate sense coils positioned at defined locations. This segmentation allows each component to be manufactured and positioned independently with standardized tolerances, reducing the cumulative precision requirements compared to a fully integrated single-piece design. The modular approach enables compact arrangement while maintaining manufacturability.

The patent uses specific geometric parameters (odd number of turns, asymmetrical positioning distances, coil dimensions) that are optimized to reduce sensitivity to manufacturing variations. By carefully selecting these parameters, the design achieves compact dimensions while the mathematical relationships in the eddy current model provide robustness against small dimensional deviations, balancing compactness with manufacturing feasibility.