Position Detection Device Spacing Fluctuation Suppression
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Solution Overview
Problem
Conventional position detection devices for reciprocating shafts, such as those in vehicle steering systems, experience accuracy errors due to vibrations and eccentric mounting, leading to inaccuracies in detecting the position of the rack shaft.
Innovation Solution
A position detection device comprising a substrate with an excitation coil generating a magnetic field, detection coils linked to the magnetic flux, and a calculation unit that calculates the position based on induced voltage, along with a spacing fluctuation suppression structure to maintain a constant distance between the substrate and the detection object, thereby stabilizing the detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetoresistive element detection is used, then position detection can be achieved, but detection accuracy deteriorates when vibrations occur or when the moving member is mounted eccentrically
Solution Approach 1:
The patent replaces the magnetoresistive element-based mechanical detection system with an electromagnetic induction-based system. The excitation coil generates a magnetic field that interacts with the detection coil to induce voltage signals for position detection. This substitution eliminates the mechanical contact and magnetic field interference issues that cause inaccuracies under vibration and eccentric mounting conditions.
Solution Approach 2:
The patent changes the detection parameter from magnetic field interaction (magnetoresistive elements) to electromagnetic induction (coils). By using the induced voltage in the detection coil as the detection parameter, the system becomes insensitive to vibrations and eccentric mounting, as these factors do not affect the electromagnetic induction process in the same way they affect magnetic field-based detection.
2Measurement precision
If the distance between the substrate and detection object varies due to vibration, then the detection system remains simple, but position detection accuracy decreases
Solution Approach 1:
The patent employs a dynamic compensation approach where the system continuously adapts to spacing variations through software processing of the induced voltage signals. Rather than adding complex mechanical spacing control mechanisms, the system dynamically adjusts the detection algorithm to account for changes in the magnetic field coupling caused by vibration-induced spacing variations.
Solution Approach 2:
The patent implements feedback through the calculation unit that processes the induced voltage signals from the detection coil. The system uses the signal characteristics to infer position information while compensating for spacing variations, creating a feedback loop that maintains detection accuracy despite changes in the distance between the substrate and detection object.
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 position detection accuracy deterioration caused by vibrations and eccentric mounting, ensuring precise detection of the rack shaft's position even under varying conditions.
Implementation Method 1
an excitation coil that is positioned to face the moving member and parallel to the moving direction of the moving member for generating a magnetic field in an area including the detection object
Implementation Method 2
a detection coil that is 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 attached to the moving member, a substrate provided with an excitation coil being positioned to face the moving member and parallel to the moving direction of the moving member 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 spacing fluctuation suppression structure that suppresses fluctuations in a spacing between a facing surface facing the detection object and the detection object in the substrate.