Position Sensor With Differential Magnetic Flux Detection
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Solution Overview
Problem
Existing position sensors for detecting the rotation angle of a moving body, such as a throttle grip on a motorcycle, face complications due to the influence of external magnetic fields, leading to increased structural complexity and the need for multiple magnetic sensors.
Innovation Solution
A position sensor configuration using a magnet with radially divided magnetic poles and two magnetic sensors positioned to detect magnetic fluxes in opposite directions, with an anomaly detection circuit to differentiate between internal and external magnetic field influences, allowing for simplified structure and effective detection of rotation angles and external magnetic field impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three magnetic sensors are mounted to detect external magnetic field influence, then detection accuracy is improved, but device complexity and number of parts increase
Solution Approach 1:
The patent extracts the external magnetic field detection function from the main sensor system by using the difference in detection signals from two magnetic sensors. Instead of adding a third sensor specifically for external field detection, the system uses the signal difference between two sensors to identify and compensate for external field effects, thereby reducing the number of components while maintaining detection accuracy.
Solution Approach 2:
The two magnetic sensors serve multiple functions: they detect both the internal magnetic field from the rotating magnet and the external magnetic field influences simultaneously. By using the difference between their signals, the system achieves external field compensation without requiring dedicated separate sensors for each function, thus reducing overall device complexity.
2Measurement precision
If magnetic sensors are used to detect rotation angle, then detection capability is improved, but sensitivity to external magnetic fields increases
Solution Approach 1:
The system uses the difference signal from the two magnetic sensors as feedback to identify and compensate for external magnetic field effects. The anomaly detection circuit continuously monitors the signal difference and provides feedback to correct the rotation angle detection, thereby maintaining accuracy despite the presence of external magnetic fields.
Solution Approach 2:
The patent introduces an intermediary approach by using the difference between two sensor signals as a mediator to identify external field effects. This difference signal acts as an intermediary that separates the useful signal (internal magnetic field) from the harmful interference (external magnetic field), enabling selective detection and compensation.
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 detection of the rotation angle of a moving body while minimizing the number of components and structural complexity, effectively mitigating the effects of external magnetic fields on the sensor's accuracy.
Implementation Method 1
a magnet (10) that rotates in conjunction with a moving body, and a magnetic sensor (21, 22) that detects a magnetic flux generated by the magnet (10)
Implementation Method 2
two magnetic sensors (21, 22) each detecting the direction of a magnetic flux
Data Source
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AI summary
A position sensor according to the present invention includes: a magnet configured to move together with a moving body and generate a first magnetic flux along a specific movement direction of the moving body and a second magnetic flux along the opposite direction to the specific movement direction of the moving body; and a sensor configured to detect the direction of the first magnetic flux and the direction of the second magnetic flux. The magnet is configured by at least one magnet having at least two pairs of magnetic poles to be paired formed thereon.