Inductive Displacement Sensor Winding and Field Confinement
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Solution Overview
Problem
Existing inductive displacement sensors are sensitive to assembly inaccuracies, conductive parts in the measurement zone, and lack linearity, leading to precision and robustness issues, and are fragile, making them unsuitable for industrial applications.
Innovation Solution
The design includes a transducer with secondary windings arranged in a specific configuration with multiple turns and metallization levels to improve linearity and robustness, and the addition of field confinement parts to adjust the target-transducer distance, reducing linearity errors and sensitivity to parasitic disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional secondary windings are used in inductive displacement sensors, then the device structure is simple, but the measurement precision and linearity are poor
Solution Approach 1:
The secondary winding is divided into multiple discrete turns (at least 3 turns) instead of a continuous winding. Each turn is spatially separated and contributes to the overall measurement signal, improving linearity and reducing sensitivity to assembly variations while maintaining a manageable structural complexity
Solution Approach 2:
Each turn of the secondary winding is positioned at a specific location relative to the primary winding and target, with optimized dimensions (radial width wr, axial width wz) to maximize local coupling efficiency. This localized optimization of each turn's geometry and position enhances overall measurement precision without requiring complete redesign of the entire winding structure
2Measurement precision
If the transducer and target are placed close together to improve measurement sensitivity, then the measurement precision improves, but the sensitivity to parasitic disturbances increases
Solution Approach 1:
The patent introduces field confinement parts (magnetic shields or conductive screens) that actively manage parasitic electromagnetic fields. These components convert harmful parasitic disturbances into beneficial field confinement effects, directing the electromagnetic field primarily through the intended measurement path between the primary winding and target, thereby reducing sensitivity to external parasitic disturbances while maintaining close transducer-target positioning for high measurement sensitivity
3Measurement precision
If conventional windings are used without field confinement, then the device structure is simple, but linearity errors are large
Solution Approach 1:
Field confinement parts are introduced as intermediary elements between the primary winding and the external environment. These intermediaries (magnetic shields or conductive screens) mediate the electromagnetic field distribution, confining it to the desired measurement zone and eliminating field distortion that causes linearity errors, without requiring complex modifications to the winding structure itself
4Reliability
If the sensor is made more robust for industrial applications, then the reliability improves, but the measurement precision may deteriorate
Solution Approach 1:
The patent designs the secondary winding with flexible parameters (number of turns, radial width wr, axial width wz) that can be optimized for different application requirements. The field confinement parts are also designed with adjustable positioning and dimensions, allowing the system to adapt between robustness-oriented configurations (for industrial reliability) and precision-oriented configurations (for high measurement accuracy), making the sensor suitable for various industrial applications with different priority requirements
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
The solution enhances the linearity and robustness of inductive displacement sensors, reducing linearity errors and sensitivity to disturbances, making them more suitable for industrial use and improving measurement accuracy.
Implementation Method 1
The transducer includes a primary winding, or inductor, suitable for producing an alternating electromagnetic field, and at least one secondary winding at the terminals whereof an alternating voltage is induced, also referred to as electromotive force or EMF, in the presence of the electromagnetic field produced by the primary winding
Implementation Method 2
The target is a partially or fully conductive element, also referred to as a coupling armature, the presence and/or movement whereof in front of the transducer modifies the coupling between the primary winding and the secondary winding
Data Source
AI summary
A transducer for an inductive displacement sensor includes a secondary winding of 2N turns of alternating directions extending in a zone of length Dtot, the winding including: a first coiled conductive section forming N half-turns, extending between a first end of the winding, situated at the midpoint of the length Dtot, and a first point of the winding, situated at one end of the length Dtot; a second section forming N half-turns, extending between the first point and a second intermediate point situated at the midpoint of the length Dtot; a third section forming N half-turns, extending between the second point and a third intermediate point situated at a second end of the length Dtot; and a fourth section forming N half-turns, extending between the third point and a second end of the winding situated at the midpoint of the length Dtot.