Displacement Sensor Return Core Shielding and Housing Cavity
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Solution Overview
Problem
Existing displacement sensors face challenges in robustness against external magnetic fields and increasing cost pressures, requiring a cost-effective and robust solution.
Innovation Solution
A displacement sensor design featuring a receiver device with a functional core surrounded by a receiving coil and a return core that shields from external electromagnetic fields, using a crystalline alloy for the return core and an amorphous alloy for the functional core, housed in an injection molding compound with a cavity to support the return core and reduce mechanical stress, and employing inductive coupling for signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the return core is designed exactly the same as the functional core to enable single-process production, then manufacturing cost is reduced, but the return core cannot be securely supported without mechanical pressure during production
Solution Approach 1:
The housing is segmented into two parts: a first housing part that supports the functional core, and a second housing part that forms a cavity for the return core. This segmentation allows each core to be supported in its own dedicated space, enabling the return core to be securely held without mechanical pressure from injection molding while maintaining production efficiency.
Solution Approach 2:
The cavity acts as an intermediary structure between the housing and the return core. By providing a dedicated cavity that receives and holds the return core, the design eliminates the need for the return core to withstand injection molding pressure, while still securing it in place through the cavity's geometric constraints.
2Reliability
If an amorphous core is used for the functional core, then magnetic properties are improved, but cost increases significantly compared to crystalline materials
Solution Approach 1:
Different material qualities are assigned to different components based on their specific functional requirements. The functional core uses expensive amorphous material where high magnetic performance is critical for sensor operation, while the return core uses inexpensive crystalline material where only basic shielding and structural functions are needed. This local differentiation optimizes both performance and cost.
3Strength
If the return core is firmly fastened to multiple holding elements, then mechanical stability is improved, but thermal expansion stress increases due to different expansion coefficients
Solution Approach 1:
Instead of firmly fastening the return core to all holding elements, the design uses only at least one holding element for attachment. This partial action provides sufficient mechanical stability to prevent excessive movement while leaving the core free to expand and contract thermally without generating stress from rigid constraints at multiple points.
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 results in a more cost-effective and robust displacement sensor with reduced interference from external magnetic fields, achieving over 60% cost savings and improved shielding effectiveness, particularly at low frequencies.
Implementation Method 1
an excitation coil (4) for exciting an alternating electromagnetic field, a receiver device for inductively receiving the alternating electromagnetic field
Implementation Method 2
a return core, the return core being designed to shield the functional core from an external electromagnetic field. External magnetic fields are largely routed past the functional core by the return core
Data Source
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Figure 5~6
AI summary
The invention relates to a displacement sensor for sensing a displacement, comprising: an excitation coil (4) for producing an alternating electromagnetic field; a receiving device for inductively receiving the alternating electromagnetic field and for outputting an output signal dependent on the received alternating electromagnetic field, the receiving device having a functional core (76), which is surrounded by at least one receiving coil (5); and a return core (77), the return core (77) being designed to shield the functional core (76) from an external electromagnetic field, and the receiving device comprising a housing having a cavity (86), in which cavity the return core (77) is arranged.