Radial Magnetic Angle Sensor Using Ring Irregularities
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Solution Overview
Problem
Current mechanical absolute angle measurement systems for rotary machines are costly and require complex electronics placement, as they are typically axially arranged, making it difficult to integrate motor control electronics parallel to the motor shaft while maintaining high accuracy.
Innovation Solution
A device with a magnetic ring and two magnetic field sensors arranged radially around the shaft, where the evaluation unit compares signals to determine the mechanical absolute angular position, exploiting production irregularities and allowing for a cost-effective, space-optimized design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If axial sensor arrangement is used for mechanical absolute angle measurement, then measurement precision is improved, but device complexity and cost increase due to electronics placement requirements
Solution Approach 1:
The patent transitions from axial sensor arrangement (one dimension) to radial sensor arrangement (another dimension). The magnetic ring with multiple magnetic poles is arranged radially around the shaft, and sensors detect magnetic fields in the radial direction, enabling absolute angle measurement without requiring electronics to be placed above the shaft end.
Solution Approach 2:
The magnetic ring serves multiple functions: it generates the magnetic field for angle measurement and its production irregularities serve as the unique fingerprint for absolute position determination. The system uses the same magnetic field generation mechanism for both field creation and position identification.
2Measurement precision
If axial sensor arrangement is used for mechanical absolute angle measurement, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent transitions from axial sensor arrangement (one dimension) to radial sensor arrangement (another dimension). The magnetic ring with multiple magnetic poles is arranged radially around the shaft, and sensors detect magnetic fields in the radial direction, enabling absolute angle measurement without requiring electronics to be placed above the shaft end.
3Device complexity
If radial sensor arrangement is used, then device complexity is reduced, but measurement precision deteriorates due to inability to perform mechanical absolute angle determination
Solution Approach 1:
The patent applies local quality by intentionally introducing or utilizing production irregularities at specific locations on the magnetic ring. Each magnetic pole has unique irregularities (in magnetization, geometry, or material properties) that serve as local fingerprints. The sensors detect these localized variations to determine absolute position.
Solution Approach 2:
The patent uses magnetic field strength variations as an analog to color changes. The production irregularities create unique magnetic field signatures for each magnetic pole, similar to how different colors identify different objects. The evaluation unit identifies these unique magnetic signatures to determine absolute angular position.
4Manufacturing precision
If production irregularities are used for angle determination, then manufacturing precision requirements are relaxed, but measurement reliability must be maintained
Solution Approach 1:
The system uses feedback by comparing the detected magnetic field pattern with stored reference patterns. The evaluation unit continuously monitors the magnetic field signals, identifies the current position based on pattern matching, and can compensate for variations. This feedback mechanism ensures reliable measurement despite manufacturing tolerances.
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 mechanical absolute angle measurement with less than 1% inaccuracy, reducing costs and simplifying the structure of rotary machines by allowing motor control electronics to be placed parallel to the shaft.
Implementation Method 1
The magnetic field sensors are set up to detect the magnetic fields which are provided by the magnetic ring
Data Source
Figure 1~3
Figure 4I~4II
Figure 5~6
AI summary
A vehicle, a rotating machine, and a device for the mechanically absolute determination of the angle of a shaft (2) of a rotating machine (3) are proposed. The device comprises: - a magnetic ring (4) with a plurality of magnetic poles, - a first magnetic field sensor (5), - a second magnetic field sensor (6), and - an evaluation unit, wherein - the magnetic ring (4) is configured to be arranged on the shaft (2) of the rotating machine (3), - the magnetic field sensors (5) are configured to detect the magnetic fields of the poles of the magnetic ring (4) passing through during rotation of the shaft (2), and - the evaluation unit is configured to - compare signals based on magnetic field signals from the magnetic field sensors (5), - identify manufacturing irregularities of the magnetic ring (4), and - perform a mechanically absolute determination of the angle of the shaft (2) based on the identified irregularities.