Rotational Angle Sensor With Recessed Magnet Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing measuring systems for determining the angle of rotation of a shaft are prone to interference from external magnetic fields, which affects accuracy and requires complex shielding and differential measurements.
Innovation Solution
A measuring system comprising a magnetically conductive encoder and a sensor unit with two magnetic field sensors positioned within a recess of a pot-shaped permanent magnet, allowing for contactless angle detection with reduced interference and simplified construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic field sensors are used with external shielding, then protection against interference is improved, but device complexity increases
Solution Approach 1:
The sensor unit is nested within the recess of the permanent magnet, creating a compact integrated structure where the magnet itself provides the shielding function, eliminating the need for separate external shielding components
Solution Approach 2:
The permanent magnet and sensor unit are merged into a single integrated component, where the magnet serves dual purposes: generating the magnetic field for rotation detection and providing magnetic shielding against external interference
2Measurement precision
If differential measurements with multiple sensors are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The permanent magnet creates a highly localized and controlled magnetic field environment within its recess, where the field geometry is predetermined by the magnet's shape and magnetization, eliminating the need for complex differential measurements to compensate for external fields
Solution Approach 2:
The sensor unit is extracted from conventional complex arrangements and placed directly within the magnet's recess, simplifying the overall system while maintaining measurement precision through the controlled magnetic environment
3Ease of manufacture
If encoder is positioned far from axis of rotation, then sensor unit placement is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The encoder is nested within the magnet's recess structure, allowing precise positioning to be achieved through the magnet's own geometry rather than requiring separate precision mounting features
Solution Approach 2:
The magnet's recess serves multiple functions: housing the sensor unit, providing magnetic shielding, and establishing precise encoder positioning, thereby simplifying manufacturing requirements
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 system provides precise angle determination between 0° and 360° with reduced susceptibility to external magnetic fields, enhancing robustness and accuracy, and eliminating the need for complex shielding and differential measurements.
Implementation Method 1
The magnet unit has a permanent magnet with a magnetization extending essentially or exactly parallel to the axis of rotation
Implementation Method 2
The first magnetic field sensor is sensitive with respect to a first magnetic field component that is perpendicular or substantially perpendicular to the axis of rotation
Data Source
AI summary
A measuring system for determining an angle of rotation of a shaft, which is rotatable about an axis of rotation, having a magnetically conductive encoder, which is spaced from the axis of rotation and fixedly connected to the shaft, a magnet unit with a permanent magnet, and an intermediate sensor unit having two magnetic field sensors. The permanent magnet has a magnetization extending parallel to the axis of rotation, and a circular-cylindrical recess having a bottom, an axis of symmetry extending perpendicular to the bottom, and a diameter, the sensor unit being completely arranged within the recess and stationary with respect to the permanent magnet. The first distance of the encoder from the axis of rotation being less than half the diameter of the recess, the encoder being arranged in a direction parallel to the axis of rotation at a second distance from the sensor unit.