Gas Sensor Cover Assembly Water Splash Protection

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Solution Overview

Problem

Gas sensors installed in internal combustion engine exhaust systems are prone to breakage due to water splashing, and existing solutions that prevent water adhesion either delay the response time or increase thermal capacity, compromising the sensor's performance.

Innovation Solution

A gas sensor design featuring a cover assembly with an outer and inner cover, where the gas inlet is oriented to split the gas flow into an outer and inner stream, directing water droplets away from the sensor element while maintaining quick gas access, thus preventing water entry without delaying measurement response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a water-repellant protective film is installed on the gas sensor element to prevent water adhesion, then the sensor element is protected from breakage, but the response time is delayed and thermal capacity is increased

Engineering Contradiction:

Improvesensor element breakage preventionVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The protective cover assembly is divided into an outer cover and an inner cover, creating a segmented structure that separates the water-blocking function (outer cover) from the gas sensing function (inner cover). This segmentation allows water to be blocked at the outer cover while maintaining direct gas access to the sensor element through the inner cover, thus preventing breakage without delaying response time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner cover acts as an intermediary component between the outer water-blocking cover and the gas sensor element. It provides a protected pathway for exhaust gas to reach the sensor element while preventing water droplets from contacting the sensor, thereby mediating between protection requirements and response speed requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the gas inlet is positioned to allow direct gas flow to the sensor element for quick response, then response speed is maintained, but water droplets can easily enter and adhere to the sensor element causing breakage

Engineering Contradiction:

Improvegas sensor response speedVSAvoidwater droplet adhesion

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The dual-cover structure segments the gas flow path into an outer stream (between covers) and an inner stream (through inner cover). The outer cover blocks water while the inner cover allows gas passage, creating separate pathways that simultaneously achieve water protection and rapid gas response.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner gas inlet is oriented at an angle (not perpendicular to the exhaust flow direction), creating a three-dimensional flow path that directs water droplets away from the sensor element while allowing gas to reach the sensor through the inner cover. This angular orientation adds a dimensional component to the flow path that prevents water adhesion.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If a protective cover assembly is added to prevent water entry, then water protection is improved, but device complexity increases

Engineering Contradiction:

Improvewater protectionVSAvoidcover assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective cover assembly is segmented into an outer cover and an inner cover, each performing a specific function. The outer cover handles water blocking while the inner cover handles gas passage, allowing for modular design and easier manufacturing compared to a single complex protective structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The outer cover serves multiple functions: it blocks water droplets, guides exhaust gas flow, and provides structural protection. The inner cover serves as both a protective barrier and a gas inlet conduit. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity.

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

The design effectively prevents water-induced breakage of the gas sensor while maintaining its responsiveness and activation speed, ensuring accurate and timely gas concentration measurements.

Implementation Method 1

the gas inlet is oriented to split the gas flow into an outer and inner stream, directing water droplets away from the sensor element

Methodology Applied

Scientific EffectFluid flow separation:

Data Source

PatentUS7901556B2Gas sensor equipped with cover assembly designed to minimize splashing of sensor element with water

Publication Date: 2011.03.08 DENSO CORP

AI summary

A gas sensor is equipped with a cover assembly made up of an outer cover and an inner cover in which a gas sensor element is disposed. The outer cover has an outer gas inlet and an outer gas outlet formed closer to a top end of the cover assembly than the outer gas inlet. The inner cover has an inner gas inlet formed closer to the top end of the cover assembly than the outer gas inlet. The inner gas inlet is oriented to minimize the entry of drops of water having entered along with a gas to be measured into the inner cover to avoid splashing of the gas sensor element with the water.