AMT Hall Sensor Layout for Magnetic Interference Detection
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Solution Overview
Problem
Existing automated manual transmissions (AMTs) face interference from strong external magnetic fields, which can disrupt sensor-based gear position determination, particularly in environments like aluminum smelters and scrap yards, without feasible shielding or additional sensor setups being complex and costly.
Innovation Solution
A sensor arrangement with permanent magnets on shift rods and 3D Hall sensors aligned in a common horizontal plane detects magnetic interference by evaluating simultaneous signal changes across multiple sensors, distinguishing interference from gear shifts using defined signal tolerances and observation periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Hall sensors are used for displacement sensing in AMT, then reliability and robustness against environmental influences are improved, but susceptibility to strong external magnetic interference fields worsens
Solution Approach 1:
The sensor system is segmented into multiple independent Hall sensors (at least two) positioned at different locations. Each sensor monitors its own signal independently, and the control unit compares signals across sensors to detect interference patterns. This segmentation allows the system to maintain reliability while identifying magnetic interference through differential signal analysis.
Solution Approach 2:
The control unit continuously monitors Hall sensor signals and implements feedback control by comparing current signals with reference values and signals from other sensors. When interference is detected through signal deviation beyond tolerance thresholds, the system generates feedback to trigger protective measures such as disabling affected sensors or alerting the driver, thereby maintaining overall system reliability despite magnetic interference.
2Object-affected harmful factors
If ferromagnetic shielding is implemented to protect against magnetic interference, then protection against external magnetic fields is improved, but device complexity and spatial requirements worsen
Solution Approach 1:
Instead of enclosing sensors in ferromagnetic shielding, the invention extracts and monitors the magnetic field signals directly using multiple Hall sensors positioned at different locations. The control unit processes these signals to detect and compensate for interference, effectively removing the need for physical shielding structures while maintaining protection against magnetic interference.
Solution Approach 2:
The mechanical/physical shielding approach (ferromagnetic enclosures) is replaced with an electronic/software-based solution. Multiple Hall sensors combined with signal processing algorithms in the control unit substitute for physical shielding, reducing device complexity and spatial requirements while achieving equivalent or superior interference protection.
3Measurement precision
If additional sensors or shielded housings are added to mitigate magnetic interference, then measurement precision under interference conditions is improved, but manufacturing cost and device complexity worsen
Solution Approach 1:
The existing Hall sensors, originally designed solely for gear position detection, are made multi-functional by utilizing their signals for both position measurement and magnetic interference detection. The control unit processes these same signals to identify interference patterns, eliminating the need for additional dedicated interference detection sensors and maintaining manufacturing simplicity.
Solution Approach 2:
The functions of gear position detection and magnetic interference detection are merged into a single integrated process using the same Hall sensor signals. The control unit simultaneously performs position determination and interference detection by analyzing signal characteristics, thereby maintaining measurement precision under interference while avoiding additional manufacturing complexity and costs.
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
Effectively detects and mitigates the impact of strong external magnetic fields on AMT sensors, ensuring accurate gear position determination without additional equipment or complex shielding, allowing the system to adapt shifts to maintain functionality.
Implementation Method 1
signal pickups are each designed as a 3D Hall sensor
Data Source
Figure 1
Figure 2a~2d
Figure 3a~3d
AI summary
The invention relates to a sensor arrangement (46) for an automated transmission that has a shifting device (2) having a plurality of shift rods (4, 14, 24, 34) that are arranged axially parallel to one another and are able to be moved axially by way of associated shift actuators (8, 18, 28, 38), wherein the sensor arrangement (46) has a plurality of travel sensors (48, 56, 64, 72) that each consist of a signal transmitter (50, 58, 66, 74) attached to one of the shift rods and a signal receiver (52, 60, 68, 76) arranged fixedly on the housing, wherein the signal transmitters are each in the form of a permanent magnet, wherein the signal receivers are each in the form of a 3D Hall sensor, and in which the signal receivers (52, 60, 68, 76) are connected to an electronic transmission control unit (44) via electrical sensor lines (54, 62, 70, 78). In order to be able to detect an external magnetic interference field that might distort the sensor signals from the travel sensors (48, 56, 64, 72) without any additional outlay in terms of equipment, provision is made for the signal transmitters (50, 58, 66, 74) to be arranged with their magnetic poles (N, S) in the same axial orientation, and for the signal receivers (52, 60, 68, 76) to be arranged in a common plane (80) that is horizontal in their installation position.