Magnetoelastic Torque Sensor Radial Sensor Placement
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Solution Overview
Problem
Existing magnetoelastic torque sensors face challenges in accurately measuring torque due to interference from external magnetic fields, requiring complex configurations with multiple magnetized areas and sensors to compensate for these fields.
Innovation Solution
A compact magnetoelastic torque sensor design using a shaft with a single or dual magnetized area and strategically positioned magnetic field sensors, allowing for the measurement of torque and compensation of magnetic interference fields using a minimal number of sensors, with the sensors arranged at different radial distances from the shaft surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magnetized areas and sensors are used to compensate for magnetic interference fields, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transitions from planar sensor arrangement to three-dimensional radial positioning. Sensors are arranged at different radial distances from the shaft surface, creating a spatial gradient that enables interference field compensation without increasing the number of magnetized areas. This dimensional approach allows two sensors to perform the function that traditionally required multiple magnetized regions and sensors.
Solution Approach 2:
The patent changes the positional parameters of the sensors rather than increasing their quantity or adding magnetized areas. By varying the radial distance parameter, the system creates different measurement perspectives that enable mathematical separation of torque signal from interference field, achieving compensation through parameter variation rather than structural complexity.
2Measurement precision
If sensors are arranged at different radial distances from the shaft surface, then magnetic interference field compensation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system uses the differential measurements from sensors at different radial positions to calculate and compensate for interference fields. The evaluation unit processes the measurement signals mathematically, using the known radial distance differences to separate torque-induced field changes from interference fields, thereby reducing the impact of positioning tolerances.
Solution Approach 2:
By establishing fixed radial distance parameters during design and calibration, the system converts positioning precision requirements into calibrated parameter inputs. The evaluation algorithm uses these predetermined distance parameters to compute torque, reducing sensitivity to manufacturing variations compared to systems requiring precise angular or axial positioning.
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 accurate torque measurement and compensation of both homogeneous and gradient magnetic interference fields with a simplified sensor arrangement, achieving precise torque determination while maintaining a compact design.
Implementation Method 1
When a torque load is applied to the shaft, a magnetic field is created outside the shaft. This magnetic field is proportional to the torque exerted on the shaft at any point and can be measured using the torque sensor's magnetic field sensors.
Implementation Method 2
The first magnetic field sensor and the second magnetic field sensor, each configured to measure a strength of a magnetic field, are arranged at the same position in the axial direction and the circumferential direction relative to the shaft.
Implementation Method 3
Due to the proposed arrangement of the magnetic field sensors relative to the shaft and to each other, the measurements from the two magnetic field sensors can be used in such a way that the magnetoelastic torque sensor can be used to measure a torque acting on the shaft and also to compensate for and measure a magnetic interference field in the vicinity of the magnetoelastic torque sensor. In particular, homogeneous interference fields can be measured and compensated for using the magnetoelastic torque sensor.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention relates to a magnetoelastic torque sensor (10) comprising a shaft (5) with a magnetized region (51), a first magnetic field sensor (1), and a second magnetic field sensor (2). The shaft (5) has an axial direction (111), a radial direction (112), and a circumferential direction (113). The first magnetic field sensor (1) and the second magnetic field sensor (2), each configured to detect the strength of a magnetic field, are arranged at the same position relative to the shaft (5) in the axial direction (111) and the circumferential direction (113). In the radial direction (112), the first magnetic field sensor (1) is arranged at a first distance (11) from a shaft surface (53), and the second magnetic field sensor (2) is arranged at a second distance (21) from the shaft surface (53). The first distance (11) is smaller than the second distance (21).