Rotation Detection Device Using Magnetic Flux Difference
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Solution Overview
Problem
Conventional rotation detection devices can only count the passage of gear teeth, limiting the resolution of the rotation angle detection and requiring unnecessary calibration due to the inclination of magnetoresistive elements, which restricts continuous detection of the rotation angle.
Innovation Solution
A rotation detection device featuring a rotatable body with tooth tips and bottoms, a magnet generating a magnetic field, and a magnetic sensor with a signal processor that calculates the rotation angle based on differences in magnetic flux densities at multiple positions, allowing for continuous angle detection and reduced calibration procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive elements are arranged to be inclined with respect to the magnetic flux symmetry, then the binary signal accurately corresponds to gear tooth passage, but the rotation angle cannot be detected continuously due to limited resolution
Solution Approach 1:
The patent transitions from detecting only the passage of gear teeth (binary state) to detecting the actual position of gear teeth by measuring magnetic flux density differences in multiple directions (x and z components). This dimensional expansion from binary counting to continuous position measurement enables continuous rotation angle detection while maintaining accuracy.
Solution Approach 2:
The patent replaces the conventional mechanical counting method (binary signal based on gear tooth passage) with a magnetic field-based detection system. By using magnetic detection elements to measure flux density differences, the system achieves continuous analog measurement of rotation angle, substituting discrete mechanical counting with continuous magnetic field sensing.
2Ease of manufacture
If magnetoresistive elements are arranged to be inclined, then calibration becomes unnecessary for binary signal generation, but the device cannot provide continuous rotation angle detection
Solution Approach 1:
The patent employs correction values that are automatically calculated and applied by the signal processing unit based on the detected magnetic flux densities. The system self-corrects for manufacturing variations and inclination effects through computational algorithms, eliminating the need for manual calibration while enabling continuous rotation angle detection.
Solution Approach 2:
The patent changes the detection parameters from binary signal levels to continuous magnetic flux density measurements in multiple directions. By measuring both the x-component and z-component of magnetic flux density and calculating their differences, the system transforms the detection mode to achieve continuous rotation angle measurement without requiring precise mechanical alignment or calibration.
3Ease of operation
If only binary signal output is used for counting gear teeth, then the device is simple to operate, but the rotation angle detection resolution is limited
Solution Approach 1:
The patent adds dimensional information by measuring magnetic flux density in multiple directions (x and z components) rather than relying on a single binary signal. This multi-dimensional measurement approach provides continuous position information, enhancing resolution while maintaining operational simplicity through automated signal processing.
Solution Approach 2:
The patent substitutes the simple binary counting mechanism with a magnetic field-based continuous measurement system. The signal processing unit automatically converts raw magnetic flux density measurements into rotation angle information, providing high-resolution continuous detection while keeping the user interface simple and ease of operation intact.
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
Enables continuous detection of the rotation angle with suppressed calibration procedures by using a magnetic sensor to process differences in magnetic flux densities, improving the resolution and accuracy of the rotation detection.
Implementation Method 1
a magnet configured to form a magnetic field toward tooth surfaces of the tooth tip and the tooth bottom of the rotatable body
Implementation Method 2
a magnetic detection element disposed at a position between the rotatable body and the magnet and other than on the rotation axis of the rotatable body, and configured to detect magnetic flux densities in the direction of the rotation axis of the rotatable body at at least two positions
Data Source
AI summary
A rotation detection device includes a rotatable body having a tooth tip and a tooth bottom on planes normal to a rotation axis direction, a magnet forming a magnetic field toward the tooth surfaces of the tooth tip and bottom, a magnetic detection element disposed between the rotatable body and the magnet and other than on the rotation axis of the rotatable body, and detecting the magnetic flux densities in the rotation axis direction of the rotatable body at at least two positions, and a magnetic sensor having a signal processor for calculating the rotation angle of the rotatable body according to difference between the magnetic flux densities in the rotation axis direction detected at two positions and difference between the magnetic flux densities in the direction perpendicular to the rotation axis direction and a radial direction of the rotatable body detected at two positions by the magnetic detection element.