GMR Sensor Magnet Positioning via Hall Effect Field Measurement
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Solution Overview
Problem
Multiturn GMR sensors in automated clutch systems face challenges in determining the optimal magnetic field range, leading to miscounting of rotor positions due to weak or strong magnetic fields, which affects the accurate detection of the electric motor's position.
Innovation Solution
A method involving a second magnetic field sensor, such as a Hall effect sensor, is used to measure the magnetic field strength in the plane spanned by the magnetic sum vector, allowing for adjustment of the magnet to ensure the GMR sensor operates within its optimal range, eliminating the need to consider geometric distances and field strength tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic field strength is increased to improve detection range, then the sensor can detect weaker signals, but pole transitions are generated even though the magnet is not rotating, causing false readings
Solution Approach 1:
The patent adjusts the magnetic field strength parameter to fall within a specific optimal range (8-15 mT) that allows the GMR sensor to detect pole transitions accurately without generating false readings. This parameter optimization resolves the contradiction by finding the precise value that satisfies both detection range and measurement precision requirements
Solution Approach 2:
The patent replaces mechanical adjustment methods with a magnetic field characterization approach using a Hall effect sensor to measure and map the magnetic field distribution. This substitution enables precise control of the magnetic field strength parameter without mechanical intervention, allowing accurate positioning of the magnet relative to the GMR sensor
2Measurement precision
If the magnetic field strength is decreased to avoid false pole transitions, then false readings are reduced, but the magnet's pole transitions are not rotated further, causing miscounting
Solution Approach 1:
The patent establishes a lower bound for the magnetic field strength parameter (8-15 mT) that ensures the magnetic field is strong enough to produce detectable pole transitions in the GMR sensor. This parameter setting prevents miscounting while maintaining sufficient detection range through optimized field strength
3Ease of manufacture
If geometric distance measurement is used to position the magnet, then the setup process is simplified, but field strength tolerances of the magnets must be taken into account, increasing complexity
Solution Approach 1:
The patent replaces geometric distance measurement with direct magnetic field strength measurement using a Hall effect sensor. This substitution eliminates the need to calculate and compensate for field strength tolerances based on distance, as the actual field strength is measured directly at the sensor location, simplifying the overall process while reducing complexity
4Adaptability or versatility
If the GMR sensor operates outside its optimal magnetic field range, then the system is more tolerant of magnet variations, but the sensor miscounts or generates false pole transitions, reducing reliability
Solution Approach 1:
The patent identifies and maintains the GMR sensor within its optimal operating parameter range (8-15 mT magnetic field strength) through careful magnet positioning and field strength adjustment. This parameter control ensures reliable operation and accurate pole transition detection while providing sufficient tolerance to magnet variations through the optimized field strength range
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 approach ensures reliable detection of the rotor's position across multiple rotations, as the magnetic field is consistently within the specified working range, enhancing the accuracy and reliability of the GMR sensor's operation.
Implementation Method 1
a Hall-effect sensor is used as the second magnetic field sensor
Implementation Method 2
a position of the rotor is inferred by an evaluation unit from a changing magnetic field generated by the magnet
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for adjusting the position of a magnet relative to a GMR sensor, by means of which the position of the rotor is inferred by an analysis unit (21) from a variable magnetic field that is generated by the magnet (18) secured to a rotor (17) of a drive unit (14). In a method with which a highly precise signal output of the GMR sensor (20) is possible, an optimal working region of the GMR sensor is derived from a direction and/or rotation of a magnetic sum vector of the magnetic field defined by the magnet in that a magnetic field strength is measured on a plane defined by the sum vector using a second magnetic field sensor.