Axial Magnetic Field Angle Sensor for Rotor Offset Compensation
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Solution Overview
Problem
Conventional angle sensors experience inaccuracies due to axial offsets between the rotor and stator under high mechanical loads, leading to systematic measurement errors, especially when the rotor has an inclined groove and is subjected to high axial loads.
Innovation Solution
The magnetic field generated by the sensor is aligned parallel to the axis of rotation, ensuring that any axial offset between the rotor and stator results in only a tolerable angular error, and the magnetic field generator includes a metallic core and excitation coil that guides the magnetic field through the sensor coil in the axial direction, allowing for precise alignment and increased rotor diameter for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional angle sensors use an inclined groove on the rotor for measurement linearity, then measurement accuracy is improved, but under high axial loads the rotor and stator become axially offset leading to systematic measurement errors
Solution Approach 1:
Instead of having the magnetic field lines run radially through inclined grooves in the rotor (conventional approach), the patent inverts the approach by using axial magnetic field lines that pass through the rotor radially. The sensor coils are arranged radially around the rotor, and the magnetic field generator creates field lines that extend axially through the rotor body, fundamentally reversing the traditional field geometry to eliminate sensitivity to axial offsets.
Solution Approach 2:
The patent changes the geometric parameters of the magnetic field configuration from radial field lines with inclined grooves to axial field lines passing through radial sensor coils. This parameter change in field orientation and sensor arrangement makes the measurement system insensitive to axial position variations while maintaining measurement linearity and accuracy.
2Measurement precision
If the rotor diameter is increased to improve measurement accuracy, then angular resolution is improved, but the device becomes less compact
Solution Approach 1:
The patent transitions from radial sensor coil arrangements (conventional) to axial sensor coil arrangements, utilizing the axial dimension for field generation and measurement. This dimensional change allows the magnetic field to pass through the rotor in the axial direction while sensors are positioned radially, enabling accurate measurement with a more compact rotor geometry by exploiting three-dimensional field-sensor interaction.
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 enhances the accuracy of angle measurements by minimizing the impact of axial offsets and allowing for a more compact design without the need for fine slotting, thereby reducing measurement errors and improving the robustness of the angle sensor.
Implementation Method 1
The magnetic field induces an electrical voltage in the sensor coils, from which the position of the magnetic field or the rotor relative to the stator is determined.
Implementation Method 2
the magnetic field generator comprises an excitation coil for generating the magnetic field and a metallic core that is guided through the excitation coil for guiding the magnetic field
Data Source
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AI summary
The invention relates to an angle sensor (10) comprising a rotor (12) defining the angle to be measured, a magnetic field generator (42), and a stator (14) with at least one sensor coil (20). To obtain a simple, compact, and accurate angle sensor (10), it is proposed that the magnetic field generator (42) be shaped and arranged relative to the sensor coil (20) such that the magnetic field (44) it generates flows through the sensor coil (20) parallel to the axis of rotation (13) of the rotor (12).