Non-contact Hall Sensor for Locking Differential Actuator
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Solution Overview
Problem
Existing sensors for electromagnetic actuator assemblies in locking gearsets face issues with wear, mounting problems, and accuracy due to runout and interference from external magnetic fields, particularly in differential systems where precise control of wheel rotational speed is required.
Innovation Solution
A Hall-type sensor system utilizing vane interruption with a ferrous target and magnet configuration, where the ferrous target moves between the sensor and magnet to indicate engagement/disengagement, minimizing sensitivity to runout and external magnetic interference, and using concentrators to direct the magnetic field for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical positional sensor is used, then the sensor can detect the engaged/disengaged mode, but the sensor experiences wear and mounting issues
Solution Approach 1:
The patent replaces mechanical contact-based positional sensors with a magnetic field-based sensing system. A magnet is positioned on the moving component, and a magnetic sensor detects changes in magnetic field strength as the magnet moves between engaged and disengaged positions. This eliminates mechanical contact, wear, and mounting issues while maintaining detection accuracy.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the moving component and the sensor. Instead of direct mechanical contact, the magnet on the moving component modulates the magnetic field, which the magnetic sensor detects. This intermediary approach allows contactless detection and improves reliability.
2Measurement precision
If a magnetic proximity sensor is used, then the sensor can detect position, but the sensor is subject to interfering fields from adjacent electromagnetic solenoid
Solution Approach 1:
The patent positions the magnet and magnetic sensor in a specific local configuration where the magnet is placed on the moving component close to the solenoid, and the magnetic sensor is positioned to detect only the local magnetic field changes caused by the magnet's movement. This localized approach allows the system to ignore broader electromagnetic interference from the solenoid while maintaining accurate position detection.
Solution Approach 2:
Instead of trying to shield the sensor from the solenoid's magnetic field, the patent inverts the approach by using the magnet on the moving component to create a distinct, localized magnetic field signature. The magnetic sensor detects changes in this specific field rather than trying to exclude the solenoid's field, effectively reversing the problem-solving approach.
3Reliability
If a Hall type sensor with vane interruption is used, then the sensor is less sensitive to runout, but the sensor still requires precise magnetic field configuration
Solution Approach 1:
The patent changes the configuration parameters of the magnetic field system by positioning the magnet on the moving component and the magnetic sensor on the stationary component. This parameter change allows the system to detect position through magnetic field strength variations while maintaining insensitivity to runout, as the magnet-sensor geometry compensates for radial deviations.
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
The solution provides reliable and accurate sensing of the actuator assembly's mode with reduced sensitivity to runout and external magnetic fields, ensuring precise control of wheel rotational speed without mechanical contact, enhancing the differential's locking functionality.
Implementation Method 1
A Hall-type sensor utilizing vane interruption with a ferrous target and magnet configuration
Data Source
AI summary
The present invention relates to sensing engaged/disengaged modes of an electromagnetic actuator assembly, such as can be used in a locking differential or other locking gearset. Described herein is a sensor for sensing such engagement/disengagement and methods of using such a sensor. The sensor has a magnet having a north and south pole, a Hall element, and a ferrous target, wherein the ferrous target moves relative to the Hall element and magnet as a result of a position of the locking gearset.