Gas Sensor Inner Cover Flow Path Design for Responsiveness

Solution Overview

Problem

Gas sensors experience reduced responsiveness when the flow velocity of measurement-object gas is low, leading to inefficiencies in gas concentration detection.

Innovation Solution

The gas sensor design includes a first and second gas chamber with specific flow passages to minimize the path length of measurement-object gas, ensuring it reaches the sensor element quickly even at low velocities, while maintaining responsiveness at high velocities, and includes features to prevent water ingress and enhance heat retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the gas flow passage is made longer to ensure heat retention, then heat retaining properties improve, but responsiveness at low flow velocity deteriorates

Engineering Contradiction:

Improveheat retaining propertiesVSAvoidresponsiveness at low flow velocity

Core Design Contradiction:

TemperatureVSSpeed

Solution Approach 1:

The gas flow passage is divided into multiple segments with different functions: a first gas flow passage extending from the back side toward the front side for heat retention, and a second gas flow passage extending from the front side toward the back side for rapid gas delivery. This segmentation allows each passage to optimize for its specific function, resolving the contradiction between heat retention and responsiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a spatial dimension by creating bidirectional flow passages that extend in opposite directions from the sensor element. The first passage extends backward while the second passage extends forward, utilizing three-dimensional space to provide multiple pathways for gas flow simultaneously, thereby achieving both heat retention and rapid response.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If the gas flow passage is made shorter to improve responsiveness, then responsiveness at low flow velocity improves, but heat retaining properties deteriorate

Engineering Contradiction:

Improveresponsiveness at low flow velocityVSAvoidheat retaining properties

Core Design Contradiction:

SpeedVSTemperature

Solution Approach 1:

The gas flow passage is divided into multiple segments with different functions: a first gas flow passage extending from the back side toward the front side for heat retention, and a second gas flow passage extending from the front side toward the back side for rapid gas delivery. This segmentation allows each passage to optimize for its specific function, resolving the contradiction between heat retention and responsiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a spatial dimension by creating bidirectional flow passages that extend in opposite directions from the sensor element. The first passage extends backward while the second passage extends forward, utilizing three-dimensional space to provide multiple pathways for gas flow simultaneously, thereby achieving both heat retention and rapid response.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If only one gas flow passage is used, then device complexity is reduced, but responsiveness at both high and low velocities cannot be maintained

Engineering Contradiction:

Improvegas flow passage structureVSAvoidresponsiveness at high and low velocities

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The gas flow passage is divided into multiple segments with different functions: a first gas flow passage extending from the back side toward the front side for heat retention, and a second gas flow passage extending from the front side toward the back side for rapid gas delivery. This segmentation allows each passage to optimize for its specific function, resolving the contradiction between heat retention and responsiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual passage structure serves multiple functions simultaneously: the first passage provides heat retention, the second passage provides rapid gas delivery, and together they maintain responsiveness at both high and low flow velocities. This multi-functionality justifies the increased structural complexity by delivering multiple performance benefits from a single integrated design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10775357B2Gas sensor

Publication Date: 2020.09.15 NGK INSULATORS LTD

AI summary

An inner protective cover 130 of a gas sensor forms an element-chamber inlet 127 having a first outside opening 128a, a second outside opening 128b, and an element-side opening 129. The second outside opening 128b is disposed such that the path of a measurement-object gas from the first outside opening 128a to the element-side opening 129 of the element-chamber inlet 127 communicates in the middle thereof with a first gas chamber 122, and that there is a path shorter than the shortest path of the measurement-object gas extending from an outer inlet 144a through the first outside opening 128a to a gas inlet 111.