Inductive Position Measurement With Soft Magnetic Shielding
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Solution Overview
Problem
Existing inductive position measuring devices lack a compact and robust design for precise absolute position determination, particularly in applications requiring high accuracy and resistance to interference.
Innovation Solution
The use of a scale unit with two measuring graduations and a scanning unit arranged in the gap between them, featuring a soft magnetic intermediate layer between coil arrangements to separate magnetic field lines and prevent eddy currents, allowing for precise position-dependent scanning signals and a compact, robust structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two measuring graduations are arranged in parallel with a scanning unit between them, then absolute position measurement capability is achieved, but magnetic field interference and eddy currents increase
Solution Approach 1:
A soft magnetic intermediate layer is introduced between the first and second coil arrangements to act as a magnetic field mediator. This layer guides and separates the magnetic field lines from the two coil arrangements, preventing their interaction and eliminating eddy currents while maintaining the functionality of both measuring graduations for absolute position measurement
Solution Approach 2:
The magnetic field space between the two measuring graduations is segmented by the soft magnetic intermediate layer. This layer divides the magnetic flux paths, creating separate magnetic circuits for each coil arrangement, thereby preventing field line crossover and reducing magnetic interference
2Volume of moving object
If coil arrangements are placed in the gap between measuring graduations, then compact design is achieved, but crosstalk between sensors increases
Solution Approach 1:
The soft magnetic intermediate layer serves as a physical and magnetic intermediary between the two coil arrangements. It maintains the compact spacing between coils while simultaneously preventing magnetic crosstalk by providing dedicated flux paths through its high permeability material properties
Solution Approach 2:
The intermediate layer introduces local magnetic property variations in the gap region. By placing soft magnetic material with high permeability between the coils, it creates localized magnetic circuits that confine flux lines to specific regions, preventing them from reaching adjacent coil arrangements
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 configuration enables precise absolute position measurement with minimal interference, maintaining a compact and mechanically stable design suitable for applications in automation and transport systems.
Implementation Method 1
The soft magnetic material as an intermediate layer has the function of conducting the field lines of the alternating magnetic field emanating from the first coil arrangement in the layer of the intermediate layer and thus forming a closed and spatially limited magnetic circuit
Implementation Method 2
at least one intermediate layer made of soft magnetic material is arranged between the first coil arrangement and the second coil arrangement
Implementation Method 3
Due to the poor electrical conductivity, no eddy currents can arise in this material, which dampen the exciter field of the respective coil arrangement
Implementation Method 4
The absolute position is obtained by inductive scanning of two measuring graduations with slightly different periodic measuring graduations
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to the invention, the inductive position measuring device for absolute position measurement comprises a scale unit (1) with a first measuring division (11) and a second measuring division (12) running parallel to and opposite the first measuring division (11). A scanning unit (2) is arranged in a gap between the first measuring division (11) and the second measuring division (12) and is displaceable relative to the scale unit (1) in the measuring direction (X). This scanning unit (2) includes a first coil arrangement (21) for scanning the first measuring division (11) and for generating a first position-dependent scanning signal, and a second coil arrangement (22) opposite the first coil arrangement (21) for scanning the second measuring division (12) and for generating a second position-dependent scanning signal.An intermediate layer (6) made of soft magnetic material is arranged between the first coil arrangement (21) and the second coil arrangement (22), which shields the two coil arrangements (21, 22) from each other.