Magnetic Rotary Encoder Shielding for Brake Field Interference
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Solution Overview
Problem
Magnetic rotary encoder sensor systems are not used in the vicinity of electrical machines due to interference from strong magnetic fields generated by components like magnetic brakes, leading to distorted measurements and the need for more expensive and larger optical sensors.
Innovation Solution
A shielding system using deflection elements redirects interfering magnetic fields away from the measurement volume, allowing magnetic sensors to operate effectively by guiding interference fields around the measuring area without complete attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors are used in the vicinity of electrical machines with magnetic brakes, then the measurement is distorted by interfering magnetic fields, but using other sensor types (optical) increases cost and installation space
Solution Approach 1:
A shielding system consisting of magnetically conductive deflection elements is introduced as an intermediary between the magnetic brake and the magnetic sensor. This shielding system redirects the interfering magnetic field lines around the measurement volume, allowing the magnetic sensor to accurately measure the pole wheel's magnetic field without distortion from the brake's interference field.
Solution Approach 2:
The shielding system is divided into multiple deflection elements arranged in specific spatial configurations. These segmented elements work together to create a shielded measurement volume, with each element contributing to redirecting field lines from specific directions, providing comprehensive protection while maintaining sensor accessibility.
2Object-affected harmful factors
If optical sensors are used instead of magnetic sensors to avoid magnetic interference, then measurement accuracy is maintained, but installation space and cost increase
Solution Approach 1:
The magnetically conductive shielding system acts as a mediator that enables magnetic sensors to operate in magnetically disturbed environments. By redirecting interference field lines around the measurement volume, the shielding allows compact magnetic sensor installations while maintaining immunity to magnetic interference, avoiding the space requirements of optical sensor systems.
3Object-affected harmful factors
If the distance between the magnetic brake and rotary encoder sensor is increased to reduce interference, then magnetic interference is reduced, but installation space requirements increase
Solution Approach 1:
The shielding system with deflection elements is positioned between the magnetic brake and the rotary encoder sensor, creating a magnetically shielded zone. This intermediary structure redirects magnetic field lines around the sensor assembly, enabling effective interference reduction without requiring increased axial distance, thus maintaining compact installation dimensions.
Solution Approach 2:
Instead of solving the interference problem by increasing axial distance (one dimension), the shielding system uses radially arranged deflection elements to redirect field lines in three-dimensional space. This approach creates a shielded measurement volume that maintains compact axial dimensions while effectively blocking magnetic interference paths.
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 the use of magnetic rotary encoder sensors in magnetically disturbed environments, maintaining accurate measurements while being cost-effective and compact, thus overcoming the limitations of optical sensors.
Implementation Method 1
deflection elements (74) which redirect interfering magnetic field lines (14) around a spatial area, in particular around a measuring volume (76), in which a magnetic sensor (24) is intended to measure a useful field (38) of a pole wheel (26)
Implementation Method 2
xMR sensors have the following characteristics in common: they change their resistance depending on an external magnetic field
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
The invention relates to a shielding system (72) for a magnetic rotary encoder sensor system (22) in the surroundings (12) of a machine (16) with a magnetic interference field (14). The rotary encoder sensor system (22) has a magnetic sensor (24), a pole wheel (26), and preferably a pole wheel support (32), and the pole wheel (26) has a plurality of permanent magnets (28) with changing magnetic polarities in the circumferential direction (U), said magnets generating a usable field. The pole wheel support (32) is designed to be rotationally fixed to a rotating machine shaft (30), which extends in an axial direction and the rotational speed and/or angular position of which is to be determined by means of the rotary encoder sensor system (22), and when the rotary encoder sensor system (22) is assembled, the magnetic sensor (24) is positioned directly opposite the pole wheel (26) and on a pole wheel (26) rotation plane (36) which can be influenced by the interference field relative to the machine shaft (30). The shielding system (72) has at least one magnetically conductive deflection element (74) which is preferably fixed to the machine and which is shaped and dimensioned such that in the assembled state a measuring volume (76) is set which is substantially free of the interference field and which at least adjoins the magnetic sensor (24) and the permanent magnets (28) that are required to generate an analyzable usable field (38) when the interference field (14) is active.