LVDT Multi-Range Secondary Windings for High Precision
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Solution Overview
Problem
Conventional Linear Variable Differential Transformers (LVDTs) provide constant position accuracy throughout their range of motion, which may not be sufficient for applications requiring enhanced accuracy at specific locations within the stroke, limiting their position sensing capabilities.
Innovation Solution
The LVDT design incorporates a primary winding and two secondary windings, one with standard accuracy for the full stroke and another with high accuracy for a portion of the stroke, where the high-accuracy winding provides a position output with less error, achieved through a concentric arrangement of windings with varying turns and pitches, allowing for enhanced resolution in specific regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single secondary winding is used for the full stroke, then the device complexity is reduced and manufacturing is simplified, but the measurement precision is constant and may be insufficient for critical regions
Solution Approach 1:
The secondary winding is divided into two distinct segments: a first secondary winding providing standard accuracy over the full stroke, and a second secondary winding providing high accuracy over a portion of the stroke. This segmentation allows different precision levels in different regions, resolving the contradiction between constant precision and device complexity.
Solution Approach 2:
The patent applies local quality by providing enhanced measurement precision (higher turns per unit length) in the second secondary winding for the critical portion of the stroke where higher accuracy is needed, while maintaining standard precision in the first secondary winding for the full stroke. This ensures high precision where required without unnecessarily increasing complexity throughout the entire device.
2Measurement precision
If a second high-accuracy secondary winding is added for a portion of the stroke, then the measurement precision is enhanced in critical regions, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The second secondary winding is nested within the same cylindrical space as the first secondary winding, with both windings concentric around the probe. This nesting approach allows high-accuracy windings to be added without significantly increasing the overall device dimensions or manufacturing complexity, as the windings share the same spatial envelope.
Solution Approach 2:
The patent resolves manufacturing complexity by transitioning from a one-dimensional linear winding arrangement to a two-dimensional concentric arrangement. The second secondary winding is positioned radially inward relative to the first secondary winding, allowing both windings to coexist in the same axial space while providing distinct measurement functions.
3Measurement precision
If the tertiary winding has a narrower pitch for high accuracy, then the measurement precision is improved, but the winding density increases and manufacturing becomes more difficult
Solution Approach 1:
The narrower winding pitch is applied locally only in the second secondary winding for the portion of the stroke where high accuracy is required, rather than throughout the entire device. This localized application of high-density windings achieves improved resolution where needed while limiting the overall manufacturing precision requirements to specific regions.
Solution Approach 2:
The patent applies partial action by providing high-precision windings (narrower pitch) only for the portion of the stroke where enhanced accuracy is needed, rather than applying high precision throughout the full stroke. This reduces the overall manufacturing precision burden while achieving the required resolution in critical regions.
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 enables high-resolution position measurement over the entire stroke with improved accuracy in critical regions, reducing errors and enhancing the LVDT's position sensing capabilities without the need for separate high-accuracy sensors.
Implementation Method 1
a primary winding extending axially over the length of the LVDT electrical stroke
Implementation Method 2
the secondary winding and tertiary winding receive magnetic coupling from the primary winding depending on a position of the probe along the LVDT electrical stroke
Data Source
AI summary
A linear variable differential transformer (LVDT) having an electrical stroke includes a probe axially movable along a length of the LVDT electrical stroke, a primary winding extending axially over the length of the LVDT electrical stroke, and a secondary winding extending axially over the length of the LVDT electrical stroke. The LVDT further includes a tertiary winding extending axially over less than the length of the LVDT electrical stroke, the tertiary winding at least partially overlapping with the secondary winding. An advantage of the LVDT in accordance with the present disclosure is that the accuracy of the position calculated from the tertiary winding is greater relative to the total stroke of the LVDT than that calculated from the secondary winding. This is accomplished while still fitting within the envelope of a standard single output LVDT.