Ferromagnetic Scale Sensor Using Tangential Magnetic Axis
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Solution Overview
Problem
Existing sensor arrangements for scanning ferromagnetic scales with tooth-shaped structured surfaces struggle to achieve high accuracy in determining the angle of rotation and position in magnetically disturbed environments due to suboptimal magnetic field strength and distribution, leading to increased measurement errors.
Innovation Solution
The magnetic axis of the permanent magnets is oriented parallel to the edges of the tooth structure, with the sensor positioned above the tooth structure and in front of a pole surface, ensuring the highest magnetic field strength is achieved at the sensor location, and multilayer GMR sensors are used to enhance signal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor is positioned between the pole face and the tooth surface with the magnetic axis radially oriented, then the arrangement is simple and effective for speed detection, but the magnetic field strength at the sensor location is insufficient and measurement precision deteriorates in magnetically disturbed environments
Solution Approach 1:
The patent inverts the conventional radial orientation of the magnetic axis to a tangential orientation parallel to the tooth edges. This inversion repositions the sensor to a location where it can detect the maximum gradient of the magnetic field, thereby achieving high measurement precision without compromising arrangement simplicity
Solution Approach 2:
The patent changes the orientation parameter of the magnetic axis from radial to tangential, and adjusts the sensor position relative to the pole face and tooth structure. These parameter changes optimize the magnetic field gradient at the sensor location, enabling precise position determination even in magnetically disturbed environments
2Strength
If the sensor is moved closer to the edge of the pole face to increase magnetic field strength, then the field strength increases, but sensor offset due to inhomogeneous field distribution increases leading to greater measurement error
Solution Approach 1:
The patent applies local quality by positioning the sensor at a specific location where the magnetic field gradient is maximized rather than uniformly distributing the sensor across the pole face. The tangential orientation of the magnetic axis creates a localized region of optimal field gradient at the sensor position, providing high field strength without the inhomogeneous distribution problems that would cause offset errors
3Stability of the object's composition
If the magnetic axis is oriented perpendicular to the tooth surface as in conventional arrangements, then the field distribution is uniform, but the magnetic field strength at the sensor location is limited and cannot achieve high precision in disturbed environments
Solution Approach 1:
The patent inverts the conventional perpendicular orientation of the magnetic axis to a parallel orientation relative to the tooth edges. This inversion creates a non-uniform but highly gradient field distribution that the sensor can effectively detect, achieving high measurement precision while maintaining sufficient field stability through the optimized tangential configuration
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 allows for precise determination of tooth position with high accuracy, even in magnetically disturbed environments, by maximizing magnetic field strength and minimizing interference field effects, resulting in improved measurement resolution and reduced error.
Implementation Method 1
at least one permanent magnet (4) whose magnetic axis (5), which is oriented at right angles to pole surfaces (S, N) facing one another, is arranged parallel to edges of the tooth structure
Implementation Method 2
The magnetic field sensor (1) is a magnetoresistive sensor
Implementation Method 3
multilayer GMR sensors are used to enhance signal resolution
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Disclosed is an arrangement for high-resolution determination of positions on linear or circular ferromagnetic measuring rods (3) that have a teeth structure, said arrangement providing reliable results in an environment affected by magnetic interference. For this purpose, a magnetic field sensor (1) is placed at the point where the field of a permanent magnet (4) is at a maximum and is mounted across from the measuring rod (3) in such a way that the soft magnetic material of the measuring rod causes the field to strengthen further. The obtained field strength is sufficient to be able to use multilayer GMR sensors in which the resistance changes by more than 40 percent, thus allowing a high signal amplitude to be used for greater position resolution.