Torque Detector Axial Tooth Extension for Flux Leakage
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Solution Overview
Problem
Conventional torque detectors face limitations in increasing the density of magnetic flux passing through a magnetic sensor due to excessive magnetic flux leakage caused by narrower gaps between teeth, which restricts the opposing area between the permanent magnet and the teeth of the magnetic yokes.
Innovation Solution
The torque detector design includes magnetic yokes with teeth extending beyond the rings of the permanent magnet, reducing gaps and suppressing magnetic flux leakage, while maintaining a larger opposing area, thereby increasing the magnetic flux density detected by the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width of each tooth of the magnetic yokes is increased to enlarge the opposing area between the permanent magnet and the teeth, then the amount of magnetic flux transferred is increased, but the gaps between adjacent teeth become excessively narrow, causing increased magnetic flux leakage
Solution Approach 1:
The invention transitions from increasing tooth width in the radial direction to extending tooth length in the axial direction. The first teeth extend beyond the second ring and the second teeth extend beyond the first ring, creating an opposing area increase without compromising circumferential gaps, thus resolving the contradiction between detection accuracy and magnetic flux leakage
Solution Approach 2:
The invention changes the geometric parameters of the teeth by extending their length in the axial direction beyond the rings, rather than increasing their width. This parameter change allows the opposing area to be enlarged while maintaining adequate gaps between adjacent teeth, preventing excessive magnetic flux leakage
2Measurement precision
If the opposing area between the permanent magnet and the teeth is increased to enhance detection accuracy, then the magnetic flux density should increase, but the narrower gaps cause excessive magnetic flux leakage that limits further improvement
Solution Approach 1:
The invention resolves the contradiction by extending teeth in the axial dimension beyond the rings, rather than increasing radial width. This dimensional change increases the opposing area for magnetic flux transfer while preserving sufficient circumferential gaps between teeth, thereby enhancing detection accuracy without generating excessive magnetic flux leakage
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 enhances the accuracy of torque detection by increasing the magnetic flux density through the sensor, reducing signal noise, and maintaining efficient material usage and assembly precision.
Implementation Method 1
a permanent magnet that is magnetized in a circumferential direction of the torque detector
Implementation Method 2
a magnetic sensor that detects a magnetic flux density of a magnetic circuit formed of the permanent magnet, the first magnetic yoke and the second magnetic yoke
Data Source
Figure 1
Figure 2
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AI summary
A torque detector (30) includes a permanent magnet (41), a pair of magnetic yokes (60), and a magnetic sensor (31). The magnetic yokes (60) include a first magnetic yoke (60A) and a second magnetic yoke (60B). The first magnetic yoke (60A) has a first ring (61) and a plurality of first teeth (62) extending from the first ring (61) in an axial direction (ZA). The second magnetic yoke (60B) has a second ring (63) and a plurality of second teeth (64) extending from the second ring (63) in the axial direction (ZA). The first teeth (62) extend in the axial direction (ZA) beyond the second ring (63) of the second magnetic yoke (60B). The second teeth (64) extend in the axial direction (ZA) beyond the first ring (61) of the first magnetic yoke (60A).