Rotation Sensor Radial Magnetic Element Design
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Solution Overview
Problem
Conventional rotation detecting devices face challenges in accurately detecting rotational states due to unpredictable changes in magnetization orientation of iron cores, leading to fluctuating pulse signal outputs and difficulty in reducing device size along the rotational axis.
Innovation Solution
A rotation detecting device is designed with a pair of magnetic field generating portions and a magnetic field detecting portion, where the magnetic field generating portions are arranged around the axial line with opposite polarities, and the magnetic field detecting portion has a magnetic element with varying magnetization orientation along its longitudinal direction, allowing for stable magnetization changes only when specific magnetic field configurations are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the sensor coil is arranged such that the axial direction of the iron core is in parallel to the tangential direction of the rotational direction, then the device size along the rotational axis is reduced, but the magnetization orientation becomes unstable when the permanent magnet approaches the center portion
Solution Approach 1:
The patent changes the arrangement dimension from axial (parallel to rotational axis) to radial (parallel to radius of rotation). This dimensional change allows the iron core to maintain stable magnetization orientation while keeping the device compact along the rotational axis, as the radial arrangement naturally guides magnetic flux through the center of the iron core.
Solution Approach 2:
The patent introduces a magnetic flux concentrating structure (yoke) as an intermediary between the permanent magnet and the iron core. This mediator concentrates and guides the magnetic flux through the center portion of the iron core, ensuring stable magnetization orientation changes only when needed for rotation detection.
2Measurement precision
If the iron core orientation changes only when permanent magnet approaches end portions, then accurate rotation detection is achieved, but unpredictable magnetization changes occur when magnet approaches center portion
Solution Approach 1:
The patent creates different magnetic field conditions at different locations of the iron core. The radial arrangement and magnetic flux concentrating structure ensure that the center portion experiences concentrated flux while end portions experience weaker flux, making magnetization changes predictable and location-dependent.
Solution Approach 2:
The patent pre-arranges the magnetic circuit geometry and flux concentrating structures to control where magnetization changes occur. By designing the magnetic path in advance, the system ensures that magnetization orientation changes only at predetermined locations (end portions) rather than unpredictably at the center.
3Measurement precision
If the wire-shaped magnetic element extends parallel to the rotational center axis, then accurate magnetic field detection is achieved, but the device size along the rotational axis cannot be reduced
Solution Approach 1:
The patent reorients the magnetic element from axial extension (parallel to rotational axis) to radial extension (parallel to radius of rotation). This dimensional change reduces the device footprint along the rotational axis while maintaining detection accuracy through the concentrated magnetic flux at the iron core center.
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 accurate detection of rotation by preventing unpredictable magnetization changes and allowing for a reduced device size along the rotational axis, with enhanced magnetic flux density at the center portion of the detecting element.
Implementation Method 1
a detection coil is wound around a wire-shaped magnetic element capable of generating a large Barkhausen jump
Data Source
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AI summary
A rotation detecting device includes rotation detecting device includes a first supporting member and a second supporting member disposed around an axial line. The rotation detecting device further includes a pair of magnetic field generating portions for generating a magnetic field in a region between the first supporting member and the second supporting member. The rotation detecting device further includes at least one magnetic field detecting portion attached to the second supporting member for detecting the magnetic field. The rotation detecting device further includes a first magnetic member for covering one end portion of the magnetic field detecting portion and a second magnetic member for covering the other end portion of the magnetic field detecting portion.