Segmented Shaft Position Sensing Under Vibration-Induced Tilt
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Solution Overview
Problem
Conventional position detection devices for shafts that move forward and backward in an axial direction suffer from detection errors due to shaft tilting caused by vibrations, leading to inaccurate position detection.
Innovation Solution
A position detection device with an excitation coil and detection coils configured to generate and detect alternating current magnetic fields, utilizing detection targets with specific alignment and spacing to minimize the impact of shaft inclination, ensuring accurate position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the shaft moves in the axial direction using a conventional position detection device, then the position can be detected, but detection errors occur when the shaft tilts due to vibration
Solution Approach 1:
The detection coil is divided into four portions (first to fourth portions) arranged in the axial direction of the shaft. Each portion corresponds to a specific detection target portion, allowing segmented detection of the shaft position along its length. This segmentation enables the system to maintain accurate position detection even when the shaft tilts, as the multiple portions provide redundant measurement points that are less susceptible to single-point errors caused by inclination.
Solution Approach 2:
The invention transitions from a single-plane detection approach to a multi-dimensional detection scheme by arranging detection coil portions and detection target portions both radially and axially. The detection coil portions are positioned at different radial distances from the shaft center, while also being distributed along the axial direction. This spatial distribution in multiple dimensions ensures that magnetic flux linkage remains stable even when the shaft tilts, as the three-dimensional arrangement provides geometric compensation for inclination effects.
2Device complexity
If the detection coil uses a simple wiring pattern on a single substrate, then the device complexity is reduced, but detection accuracy deteriorates when shaft inclination occurs
Solution Approach 1:
Different portions of the detection coil are designed with specific local characteristics to optimize their function. The first to fourth portions are positioned at different locations along the axial direction with specific radial distances from the shaft center. Each portion has optimized winding patterns and dimensions tailored to its specific position, allowing the coil structure to maintain detection accuracy across various shaft positions and inclination angles while managing overall complexity through localized optimization rather than uniform 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
The device effectively suppresses detection errors caused by shaft inclination, enabling high-accuracy position detection of shafts by maintaining consistent magnetic flux distribution despite tilting.
Implementation Method 1
an excitation coil that generates an alternating current magnetic field; a detection target fixed to the shaft and in which the magnetic flux of the alternating current magnetic field is chained together; and a detection coil in which the magnetic flux of the alternating current magnetic field is chained together
Implementation Method 2
the detection coil has first to fourth portions where an induced voltage is induced by the magnetic flux of the alternating current magnetic field chained together
Data Source
AI summary
A position detection device for detecting the position of a shaft that moves forward and backward in the axial direction in a predetermined range includes an excitation coil that generates an alternating current magnetic field, a detection target fixed to the shaft and in which the magnetic flux of the alternating current magnetic field is chained together, and a detection coil in which the magnetic flux of the alternating current magnetic field is chained together, wherein the detection coil has first to fourth portions where an induced voltage is induced by the magnetic flux of the alternating current magnetic field chained together, and connection portions connecting the first to fourth portions, wherein the first to fourth portions each extend along the coil longitudinal direction which is parallel to the axial direction, and at least a portion of each is aligned perpendicular to the coil longitudinal direction, wherein the detection target has a first detection target portion at least partially facing the first portion in the first predetermined range of the predetermined range, a second detection target portion at least partially facing the second portion in the second predetermined range of the predetermined range, a third detection target portion at least partially facing the third portion in the third predetermined range of the predetermined range, and a fourth detection target portion at least partially facing the fourth portion in the fourth predetermined range of the predetermined range, wherein the induced voltage induced in the first to fourth portions varies with the position of the first to fourth detection target portions relative to the first to fourth portions respectively, and wherein the first detection target portion, the second detection target portion, the third detection target portion, and the fourth detection target portion are spaced apart in the axial direction of the shaft.