Sensor with Coated PCB Cavity for Reduced Air Gap Detection

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Solution Overview

Problem

Existing sensor assemblies struggle to detect magnetic fields at air gap distances less than 1 mm due to housing clearance requirements, which compromises the reliability of magnetic field detection in electrical machines.

Innovation Solution

A sensor design featuring a printed circuit with a coating layer forming a cavity for the sensitive component, where the detection surface is flush with the cavity opening, obscured by a protective film, allowing for a reduced air gap distance while maintaining protection and effective magnetic field detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sensitive component is enclosed in a housing made of non-magnetic material to prevent shocks and intrusion of foreign bodies, then the protection of the sensitive component is improved, but the air gap distance increases making magnetic field detection unreliable

Engineering Contradiction:

Improveprotection of sensitive componentVSAvoidmagnetic field detection

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The invention extracts the protective function from a separate housing structure and integrates it into the printed circuit board itself through a coating layer. This eliminates the need for additional housing thickness while maintaining protection against shocks and foreign bodies, thereby reducing the air gap distance without compromising the sensitive component.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the protective function with the printed circuit board structure by forming a coating layer directly on the circuit board. This integration combines the structural support, electrical connection, and protection functions into a single component, eliminating the need for a separate housing and reducing the overall air gap distance.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If the detection surface is exposed without protection, then the air gap distance is reduced improving magnetic field detection, but the sensitive component becomes vulnerable to shocks and foreign bodies

Engineering Contradiction:

Improvemagnetic field detectionVSAvoidshocks and foreign bodies

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention uses a thin coating layer formed on the printed circuit board to protect the detection surface. This thin film provides protection against shocks and foreign bodies while maintaining sufficient magnetic field permeability, allowing the detection surface to remain effective at reduced air gap distances without requiring a thick rigid housing.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If a housing is added to protect the sensitive component, then the protection is improved, but the device complexity and assembly clearance requirements increase

Engineering Contradiction:

Improveprotection of sensitive componentVSAvoidassembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The printed circuit board is designed to perform multiple functions simultaneously: providing structural support, establishing electrical connections, and protecting the sensitive component through its coating layer. This multi-functionality eliminates the need for separate protective housing and reduces the number of components and assembly steps.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reliable detection of magnetic fields at reduced air gap distances, enhancing the sensor's reliability and accuracy while preventing damage from foreign bodies and shocks.

Implementation Method 1

a sensor comprising a sensitive component capable of detecting the magnetic field delivered by the movement of an encoder disposed at an air gap distance

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP4006494B1Sensor capable of detecting the magnetic field of a remote encoder of an air gap

Publication Date: 2023.09.13 NTN EUROPE

Figure 1a~1b
Figure 2~3
Figure 4a~4b

AI summary

The invention relates to a sensor (4) comprising a sensitive component (5) capable of detecting the magnetic field delivered by the movement of an encoder disposed at an air gap distance, said sensor comprising a printed circuit board (7) having a face (8) on which said sensitive component is implanted having a detection surface (9) which is disposed opposite said face, said printed circuit board comprising a coating layer (16) of at least a part of the face (8), the coating layer (16) forming a cavity (17) in which the sensitive component (5) is disposed, the thickness of said coating layer being such that the detection surface (9) is flush with an opening of the cavity (17) opening into the free face (26) of said coating layer, said opening being covered by a protective film (18) which is disposed so as to cover the detection surface (9).