Position Detection Device With Magnetic Field Diffusion Suppression
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Solution Overview
Problem
Existing position detection devices for reciprocating shafts, such as those in vehicle steering systems, suffer from accuracy decline due to interference from steel materials in the vehicle body, affecting the magnetic field distribution and subsequent position detection.
Innovation Solution
A position detection device comprising a substrate with an excitation coil generating a magnetic field, detection coils interlinked with the magnetic flux, a power supply unit for alternating current, and a magnetic field diffusion suppression member, such as a shield conductor, to minimize magnetic field interference and maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a permanent magnet is used to generate a magnetic field for position detection, then the detection function is achieved, but the magnetic field distribution is affected by steel materials in the vehicle body, causing position detection errors
Solution Approach 1:
A non-magnetic material (such as aluminum or copper) is introduced as an intermediary barrier between the permanent magnet and the steel vehicle body. This intermediary layer prevents the steel materials from distorting the magnetic field distribution, thereby eliminating position detection errors while allowing the permanent magnet to continue generating the necessary magnetic field for detection.
2Measurement precision
If magnetoresistive elements are used to detect position changes, then the position detection function is achieved, but the detection accuracy declines when steel materials affect magnetic field distribution
Solution Approach 1:
The non-magnetic material serves as a protective intermediary that shields the magnetoresistive elements from magnetic field distortions caused by nearby steel components. This ensures that the magnetic field reaching the detection elements remains uniform and predictable, maintaining both accuracy and reliability of position detection even in the presence of steel materials.
3Device complexity
If no magnetic field suppression measure is taken, then the device structure remains simple, but position detection accuracy is compromised due to magnetic field spread and interference
Solution Approach 1:
A thin non-magnetic material layer is applied as a flexible barrier between the permanent magnet and the surrounding environment. This thin film effectively suppresses magnetic field spread and prevents interference from steel materials, while adding minimal structural complexity and maintaining the overall simplicity of the device.
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 solution effectively suppresses the decline in position detection accuracy by controlling the magnetic field spread and interference, ensuring precise detection of the rack shaft's position across its entire range.
Implementation Method 1
a substrate provided with an excitation coil for generating a magnetic field in an area including the detection object
Implementation Method 2
a detection coil being interlinked with a magnetic flux of the magnetic field
Data Source
AI summary
A position detection device for detecting a position of a moving member moving forward and backward in a predetermined moving direction is provided with a detection object provided at the moving member, a substrate provided with an excitation coil for generating a magnetic field in an area including the detection object, and a detection coil being interlinked with a magnetic flux of the magnetic field, a power supply unit for supplying an alternating current to the excitation coil, a calculation unit that calculates the position of the moving member based on an output voltage of the detection coil, and a magnetic field diffusion suppression member for suppressing a spread of a magnetic field generated by energization to the excitation coil.