Halbach Array Magnet Offset for Position Detection Linearity
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Solution Overview
Problem
Existing position detection apparatuses for motorcycle accelerator grips lack linear responsiveness due to uniform clearance distances between magnets and magnetic sensors, leading to suboptimal recognition of angle changes in magnetic flux vectors.
Innovation Solution
A position detection apparatus with a Halbach array configuration where the second magnet is offset from the first and third magnets, increasing the clearance distance between the second magnet and the magnetic sensor, allowing the magnetic flux vector to change more precisely, enhancing linearity of response and reducing the size of the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnets are arranged in a conventional Halbach array with equal clearance distances, then the structure is simple and compact, but the magnetic sensor cannot precisely recognize changes in the magnetic flux vector angle, resulting in poor linearity of response
Solution Approach 1:
The patent applies asymmetry by intentionally making the clearance distances between different magnets and the magnetic sensor unequal. Specifically, the first magnet is positioned closer to the magnetic sensor than the second and third magnets, creating an asymmetric Halbach array configuration. This asymmetric arrangement causes the magnetic flux vectors from the four magnets to combine in a way that produces a more linear relationship between rotor angle and detected magnetic flux vector angle, thereby improving measurement precision without significantly increasing device complexity
Solution Approach 2:
The patent applies local quality by optimizing the position of each individual magnet relative to the magnetic sensor. Instead of uniform positioning, each magnet (first, second, third, and fourth) is placed at a specific clearance distance tailored to its role in the Halbach array. This localized optimization of magnet positions ensures that the magnetic flux contributions from each magnet are balanced to achieve linear response characteristics, improving angle detection precision through targeted local adjustments
2Measurement precision
If the magnets are arranged with non-uniform clearance distances to improve linearity, then the response linearity improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by modifying the clearance distance parameters of the Halbach array magnets. Specifically, it changes from equal clearance distances to unequal clearance distances, where the first magnet has a smaller clearance distance to the magnetic sensor compared to the second and third magnets. This parameter modification transforms the magnetic flux vector characteristics to achieve linear response, improving measurement precision while establishing new design parameters that can be incorporated into manufacturing specifications
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 offset configuration improves the linearity of the magnetic sensor's response to angle changes, allowing for more precise detection of the accelerator grip's position and throttle opening, while also reducing the apparatus's size and manufacturing costs.
Implementation Method 1
a magnetic sensor that detects a vector of a magnetic flux
Implementation Method 2
a magnetic sensor formed from a Hall element or the like
Data Source
AI summary
A Halbach array is formed from first to third magnets provided to a rotor. Of shortest straight-line distances (clearance distances) between the first to third magnets and a Hall element as facing the first to third magnets after moving relative to the first to third magnets, the shortest straight-line distance between the second magnet and the Hall element is set the longest. In other words, the second magnet is placed at a position offset from the first magnet. In addition, the second magnet may be offset from the third magnet.