Segmented Permanent Magnet for Wide-Range Position Detection
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Solution Overview
Problem
Existing relative position detection devices struggle to accurately detect relative displacement over a wide range with high resolution while minimizing the size of the permanent magnet part.
Innovation Solution
A relative position detection device is designed with a permanent magnet part having two magnetic pole parts with N-pole and S-pole configurations, where the middle portion and non-middle portions are strategically positioned to vary the cross-sectional area and distance to the magnetic sensor, allowing for a wider range of magnetic flux density variation without increasing the magnet's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the permanent magnet part is designed with a slant face to decrease thickness toward the end face, then the detection range for relative displacement is widened, but the variation in magnetic flux density becomes insufficient over the wide range
Solution Approach 1:
The permanent magnet part is divided into multiple magnetic pole parts (first, second, third, and fourth magnetic pole parts) with different cross-sectional areas. Each magnetic pole part contributes to the magnetic flux density in a specific displacement range, ensuring sufficient variation across the entire wide detection range while maintaining compact dimensions.
Solution Approach 2:
Different regions of the permanent magnet part are designed with different cross-sectional areas to optimize magnetic flux density distribution. The first and second magnetic pole parts have different cross-sectional areas than the third and fourth magnetic pole parts, creating localized variations in magnetic field strength that ensure sufficient flux density variation across the wide detection range.
2Measurement precision
If the permanent magnet part size is increased to improve magnetic flux density variation, then the resolution in relative displacement detection is increased, but the device size increases
Solution Approach 1:
The permanent magnet part is segmented into multiple magnetic pole parts with varying cross-sectional areas. This segmentation allows the compact magnet structure to generate sufficient magnetic flux density variation across a wide range, achieving high resolution in relative displacement detection without increasing the overall magnet size.
Solution Approach 2:
The cross-sectional area parameter of the permanent magnet part is varied across different magnetic pole parts. By changing this geometric parameter, the patent achieves sufficient magnetic flux density variation over a wide range while maintaining a compact magnet structure, thereby improving resolution without increasing device size.
3Ease of manufacture
If the permanent magnet part has uniform cross-sectional area, then the manufacturing is simplified, but the magnetic flux density variation is insufficient over wide range
Solution Approach 1:
The permanent magnet part is divided into multiple magnetic pole parts with different cross-sectional areas. This segmentation enables the magnet to provide sufficient magnetic flux density variation over a wide detection range while maintaining a relatively compact structure, balancing manufacturing feasibility with performance requirements.
Solution Approach 2:
Different sections of the permanent magnet part are designed with different cross-sectional areas to optimize the magnetic field distribution. The first and second magnetic pole parts have different cross-sectional areas than the third and fourth magnetic pole parts, ensuring sufficient flux density variation across the wide detection range while keeping the overall structure manufacturable.
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 and high-resolution detection of relative displacement over a wide range, including rotation angles, while maintaining a compact magnet size, thereby enhancing the operation range and precision of the accelerator position sensor.
Implementation Method 1
the magnetic sensor 22 detects a variation in a magnetic flux density of the permanent magnet part 17
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
Provided is a relative position detection device that is able to easily and accurately detect the amount of relative displacement between a permanent magnet part and a magnetic sensor over a wide range, and also able to increase the resolution in the amount of relative displacement, with suppression of a size increase of the permanent magnet part. The relative position detection device includes a permanent magnet part and a magnetic sensor that are arranged so as to be displaceable relative to each other. The magnetic sensor has an upper limit value and a lower limit value of a detectable magnetic flux density. The permanent magnet part includes at least two magnetic pole parts. Each of the two magnetic pole parts is magnetized in a facing direction in which the permanent magnet part and the magnetic sensor face each other. The permanent magnet part has a middle portion including a boundary between the two magnetic pole parts and two non-middle portions adjacent to the respective sides of the middle portion in a relative displacement direction. The permanent magnet part is configured such that the middle portion and, of the two non-middle portions, at least the non-middle portion capable of facing the magnetic sensor satisfy at least one of a requirement concerning a cross-sectional area and a requirement concerning a distance to the magnetic sensor.