Inductive Shaft Position Sensor with Dual Opposing Windings
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Solution Overview
Problem
Existing inductive sensors for measuring the angular position of a shaft are susceptible to axial play and distortions due to angular movement, especially when the shaft moves axially or experiences stray movements, making it difficult to accurately determine the angular position without contact.
Innovation Solution
A device with two inductive positional sensors, each with secondary windings in mutual phase opposition, configured on a support with a common primary winding, is used to measure the angular position of a shaft from a radial position, allowing for simultaneous measurement of angular position and speed of rotation, and axial displacement by eliminating flux variations associated with longitudinal displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single inductive sensor is used to measure angular position, then the measurement is contactless and simple, but the measurement is susceptible to axial play and distortions due to angular movement
Solution Approach 1:
The single sensor is divided into two separate inductive positional sensors, each measuring different aspects of shaft position. The first sensor measures angular position while the second sensor measures axial displacement, allowing independent compensation for axial play and angular movement distortions.
Solution Approach 2:
A processing circuit acts as an intermediary that receives signals from both sensors and mathematically processes them to eliminate the harmful effects of axial play and angular movement, producing a corrected angular position measurement that compensates for these disturbances.
2Adaptability or versatility
If the shaft moves axially or experiences stray movements, then the shaft maintains operational flexibility, but the angular position measurement becomes distorted
Solution Approach 1:
The second sensor provides feedback about axial displacement, which is fed into the processing circuit. This feedback is used to calculate and eliminate the distortion it causes in the angular position measurement from the first sensor, allowing the shaft to move freely while maintaining measurement accuracy.
Solution Approach 2:
The system preemptively measures axial displacement before it can distort the angular position reading, and then applies a corrective calculation to counteract the expected distortion, thereby preventing measurement errors before they occur.
3Measurement precision
If two sensors are used to eliminate axial play effects, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
Both inductive positional sensors share a common primary winding, which merges the magnetic field generation function. This reduces the number of independent components needed and simplifies the overall device structure while still achieving accurate angular position measurement through the combination of two sensors.
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 provides a signal that is solely dependent on the angular position of the shaft, unaffected by longitudinal variations, enabling accurate measurement of angular position and axial displacement, thus overcoming the susceptibility to axial play and distortions.
Implementation Method 1
The operating principle of an inductive sensor is based upon the variation of coupling between a primary winding and the secondary windings of a transformer operating at high frequency
Implementation Method 2
The primary winding is then, for example, supplied by an external high-frequency power source, and the secondary windings are the site of currents induced by the magnetic field which is generated by the flow of current in the primary winding
Implementation Method 3
Currents induced in the target modify the currents induced in the secondary windings
Data Source
AI summary
A device for the measurement of the angular position of a shaft, having: a support upon which a primary winding and at least two secondary windings in mutual phase opposition are configured, to form a first inductive positional sensor, and a second positional sensor having at least two secondary windings in mutual phase opposition and arranged on the same support, opposite the secondary windings of the first positional sensor with respect to a median line, such that a motif is formed in each case on either side of the median line, wherein the primary winding encloses all the secondary windings. A unit having a device of this type and a target having two helixes of opposing pitches.