Vacuum Pump Electromagnet PCB Layout for Sensor Noise Isolation
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Solution Overview
Problem
Existing vacuum pumps face issues with displacement sensors being interfered by electromagnetic noise, leading to misdetection or nonconformity, and require excessive separation distances that increase the pump's size in the axial direction due to noise shielding.
Innovation Solution
The wiring patterns for sensors and electromagnets are separated radially and axially on different surfaces of the printed board, with non-overlapping layouts to prevent electromagnetic interference, and the magnetic fluxes between adjacent electromagnets are offset to reduce magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the noise generating source and the displacement sensor are provided away from each other, then electromagnetic noise interference with the sensor is reduced, but the pump size increases in the axial direction due to excessive separation distance requirements
Solution Approach 1:
The patent transitions from axial separation to radial separation of the electromagnet and displacement sensor. The electromagnet and sensor are arranged side-by-side in the radial direction rather than being separated axially, allowing them to be positioned close to each other while still maintaining electromagnetic isolation. This dimensional change resolves the contradiction by achieving noise reduction without increasing axial length.
Solution Approach 2:
The patent introduces a magnetic shield as an intermediary component positioned between the electromagnet and displacement sensor. This shield blocks magnetic field lines and prevents electromagnetic noise from reaching the sensor, allowing the two components to be placed close together radially while maintaining detection accuracy. The magnetic shield acts as a mediator that enables close proximity without interference.
2Reliability
If a shield is interposed between the electromagnet and displacement sensor, then electromagnetic noise interference is reduced, but the pump size increases due to the additional shield component
Solution Approach 1:
The patent places the magnetic shield on the radial side rather than requiring axial space. By utilizing the radial dimension for shield placement, the pump avoids additional axial length while still providing effective electromagnetic shielding. This maintains compact overall dimensions while achieving noise reduction.
Solution Approach 2:
The magnetic shield is implemented as a thin-walled structure that provides effective electromagnetic shielding with minimal material thickness. This thin-film approach reduces the volume occupied by the shield component while maintaining its noise-blocking function, thus reducing the overall pump volume increase.
3Reliability
If wiring patterns for sensor and electromagnet are separated radially and axially on different surfaces, then electromagnetic noise interference is suppressed, but device complexity increases
Solution Approach 1:
The patent combines the radial and axial separation requirements into a single printed circuit board design where the sensor wiring and electromagnet wiring are routed on opposite surfaces of the same board. This merging of multiple separation requirements into one integrated structure simplifies the overall device complexity while achieving the necessary electromagnetic isolation.
Solution Approach 2:
The printed circuit board serves as an intermediary structure that physically separates the sensor and electromagnet wiring through its thickness. The board's ground layers and routing patterns act as barriers to electromagnetic noise, providing isolation without requiring complex external shielding or separate cable management systems.
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 effectively suppresses electromagnetic noise interference with displacement sensors, preventing misdetection and nonconformity while maintaining a compact pump design.
Implementation Method 1
a radial electromagnet 51 that generates a magnetic field in a radial direction R
Implementation Method 2
a radial electromagnet 51 that generates a magnetic field in a radial direction R
Implementation Method 3
an axial electromagnet 52 that generates a magnetic field in an axial direction A
Implementation Method 4
an axial electromagnet 52 that generates a magnetic field in an axial direction A
Implementation Method 5
a radial sensor 53 that detects a position of the shaft 21 in the radial direction R
Data Source
Figure 1
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Figure 3
AI summary
An electromagnet unit in which influence of a noise on a displacement sensor is suppressed and which can be installed in a space-saving manner and a vacuum pump including the electromagnet unit are provided. An electromagnet unit includes a radial electromagnet which controls a shaft to a predetermined position, a radial sensor which detects a position of the shaft, and a printed board interposed between the radial electromagnet and the radial sensor and on which a wiring pattern for sensor connecting coils of the corresponding two radial sensors to each other and a wiring pattern connecting coils of the corresponding two radial electromagnets to each other are provided. The wiring pattern for sensor and the wiring pattern for electromagnet are disposed so as not to overlap when seen from the axial direction.