Sensor Unit Coating for Sealing Narrow Moisture Paths

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Solution Overview

Problem

Sensor bearing units face issues with humidity and contaminating particles entering through narrow passages between the sensor element and sensor body, leading to potential damage and reduced performance.

Innovation Solution

A method of applying a coating to the exterior surface of the assembled sensor unit, covering both the sensor element and sensor body, which also includes the output cable, to enhance sealing and resistance to humidity and electrostatic discharges, using a dipping process for thorough coverage and regular thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the sensor body is overmoulded on the sensor element, then the sensor unit is compact and integrated, but narrow passages are formed between the sensor element and sensor body allowing water and contaminating particles to enter

Engineering Contradiction:

Improveintegration of sensor unitVSAvoidhumidity and contaminating particles

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

A coating is applied to the sensor element and sensor body before final assembly, creating a protective barrier in advance that prevents water and contaminating particles from entering narrow passages formed during overmoulding

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A thin film coating is applied to the sensor unit components, providing a flexible protective barrier that seals narrow passages while maintaining the compact integrated structure

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If a coating is applied to the sensor unit to improve sealing, then resistance to humidity and contaminants is improved, but additional production steps are required

Engineering Contradiction:

Improvesealing against humidityVSAvoidproduction time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The coating is applied as a preliminary step before final assembly, allowing the coating process to be integrated into the manufacturing flow without requiring post-assembly disassembly or additional complex equipment

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If conventional overmoulding is used, then manufacturing is simple, but the sensor element remains vulnerable to electrostatic discharges and environmental damage

Engineering Contradiction:

Improveconventional manufacturing processVSAvoidprotection against electrostatic discharges

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The sensor unit combines the sensor element, sensor body, and protective coating into a composite structure where the coating provides electrostatic discharge protection and environmental sealing while the core components maintain their functional properties

Inventive Principle:

Principle #40Composite materials

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 coating effectively seals the sensor unit against water, aggressive chemicals, and electrostatic discharges, improving its durability and reliability without requiring changes to conventional production processes.

Implementation Method 1

Thanks to the invention, narrow passages that may be formed between the sensor element and the sensor body are covered by the applied coating layer. This improves the sealing of sensor unit against humidity, immersion in water with aggressive chemical agent such as salt, solvent, mineral grease etc...

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

Besides, the coating layer applied on sensor unit can also provide an improved resistance against electrostatic discharges.

Methodology Applied

Scientific EffectElectrostatic discharge resistance: Electrostatic Discharge

Implementation Method 3

the method comprises, after the coating step, at least a first curing step wherein the coating is cured at room temperature and at a relative humidity lower or equal to 80%. Advantageously, the method further, after the first curing step, a second curing step wherein the coating is cured at a higher temperature and at a relative humidity lower or equal to 80%.

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS20230028121A1Method for coating a sensor unit, and associated sensor unit

Publication Date: 2023.01.26 AB SKF SKF PATENT DEPARTMENT

AI summary

A sensor unit including a sensor element; a sensor body supporting the sensor element; an output cable mounted inside the sensor body and extending outward relative to the sensor body; and a coating layer covering an outer surface of the sensor element, an outer surface of the sensor body, and an entire outer surface of the output cable.