Reduced-Width Inductive Position Sensor Using Acute-Angle Windings
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Solution Overview
Problem
Designing a reduced-width inductive position sensor to replace Hall effect sensors in liquid level measurement applications, particularly in motor vehicles, which are sensitive to external magnetic fields and require improved precision and linearity without increasing bulk.
Innovation Solution
The design features secondary windings with turns that form acute angles at their longitudinal ends, allowing for a compact sensor structure by using a rhombus shape derived from hexagonal shapes without bases, reducing the sensor's width and enhancing linearity and sensitivity, with the primary winding surrounding the secondary windings and having linear portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect sensors are used for liquid level measurement, then the sensor can detect magnetic field changes, but the sensor becomes broadly sensitive to external magnetic fields and is unsuitable for electrified motor vehicles
Solution Approach 1:
The patent replaces Hall effect sensors (which detect magnetic fields) with an inductive position sensor that detects changes in inductance through electromagnetic coupling between primary and secondary windings. This substitution eliminates sensitivity to external magnetic fields while maintaining liquid level measurement capability, as the sensor responds only to changes in the conductive target's position relative to the windings.
2Measurement precision
If the number of turns in secondary windings is increased to obtain measurable induced voltages, then measurement reliability improves, but the sensor width increases and compactness is lost
Solution Approach 1:
The patent transitions from planar winding arrangements to three-dimensional stacked windings on opposite faces of the printed circuit board. Secondary windings are formed on both the first and second opposite faces of the PCB, with vias connecting corresponding turns between faces. This vertical stacking in the third dimension allows increased number of turns within a compact footprint, maintaining measurement reliability while preserving sensor compactness.
Solution Approach 2:
The patent implements nested winding structures where secondary windings on opposite faces of the PCB are electrically connected through vias, creating a compact three-dimensional arrangement. The windings are arranged in offset positions on opposite faces, allowing multiple turns to be nested within a small volume without increasing the sensor's planar dimensions.
3Length of moving object
If secondary windings are produced on two distinct layers with vias to connect turns, then sensor compactness is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the secondary windings into segments on opposite faces of the PCB, with corresponding segments connected through vias. Each face of the PCB contains a set of secondary winding turns, and vias connect matching turns between the two faces. This segmentation allows standard PCB fabrication processes to be used while achieving three-dimensional winding configuration for compact sensor design.
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 results in a more compact, sensitive, and linear inductive position sensor that is less affected by external magnetic fields, suitable for use in liquid level measurement applications, such as in motor vehicle tanks, while maintaining the typical shape and reducing mechanical faults.
Implementation Method 1
The operating principle of an inductive sensor is based on the variation in coupling between a primary winding and secondary windings of a transformer operating at high frequency and without the use of a magnetic circuit. The coupling between these windings varies with the position of an electrically conductive moving part, which is generally referred to as the 'target'. Specifically, currents induced in the target modify the voltages induced in the secondary windings.
Data Source
AI summary
Disclosed is an inductive position sensor including, on the one hand, a primary winding and, on the other hand, at least two secondary windings each having a plurality of turns formed of a succession of sides and produced on two opposite faces of a printed circuit board. Two pairs of two adjacent sides of each turn of at least one secondary winding form a first point directed toward a first longitudinal end and a second point directed toward a second longitudinal end of the printed circuit board, a projection on a plane of the printed circuit board of the two adjacent sides of each pair defining between them an acute projected angle.