Sensor Unit Coating for Sealing Narrow Moisture Paths

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Solution Overview

Problem

Sensor bearing units are prone to humidity and contaminant ingress due to narrow passages between the sensor element and sensor body, leading to potential damage from water and particles.

Innovation Solution

A method of applying a coating to the exterior surfaces of assembled sensor units, including the sensor element and body, to seal these passages and enhance resistance to humidity and electrostatic discharges, using a dipping process that ensures thorough coverage and uniform thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sensor body is overmoulded on the sensor element, then the sensor unit structure is simplified and manufacturing is easier, but narrow passages are formed between the sensor element and sensor body allowing water and contaminants to reach the sensor element

Engineering Contradiction:

Improvesensor body overmoulding processVSAvoidprotection against humidity and contaminants

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A coating layer is applied to the sensor element before the sensor body is overmoulded onto it. This preliminary coating action ensures that the sensor element surface is protected with a hydrophobic and contaminant-resistant layer before the overmoulding process creates narrow passages, thereby preventing water and contaminants from reaching the sensor element through these passages.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A thin film coating layer is applied to the sensor element surface. This flexible thin film conforms to the sensor element geometry and extends into the narrow passages formed during overmoulding, creating a continuous protective barrier against humidity and contaminants while maintaining the simplified overmoulded structure.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If a coating is applied to seal the sensor unit, then protection against humidity and contaminants is improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvesealing against humidity and contaminantsVSAvoidcoating application process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating material is formulated with specific parameters including hydrophobicity to repel water, contaminant resistance properties, and electrostatic discharge protection characteristics. By optimizing these material parameters, a single coating layer provides multiple protective functions (sealing, chemical resistance, ESD protection) simultaneously, reducing the need for multiple separate protective layers and processes.

Inventive Principle:

Principle #35Parameter changes

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, while maintaining compatibility with conventional production processes and improving the overall reliability of the sensor unit.

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 EffectPhysical barrier sealing:

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 protection: Electrostatic Discharge

Implementation Method 3

Preferably, the coating is applied in a dipping process. Alternatively, the coating may be applied by spraying or brushing.

Methodology Applied

Scientific EffectDipping process:

Data Source

PatentUS11629980B2Method for coating a sensor unit, and associated sensor unit

Publication Date: 2023.04.18 AB SKF SKF PATENT DEPARTMENT

AI summary

A method for coating a sensor unit providing at least one sensor element and a sensor body supporting the sensor element. The method includes applying, in the assembled state of the sensor unit, a coating on the exterior surface of the sensor unit such as to coat the sensor element and the sensor body.