Gas Sensor Assembly Using Element Dummy and Inversion

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Solution Overview

Problem

Existing methods for assembling gas sensors with ceramic sensor elements face challenges such as positional deviations and risk of damaging the protective film on the sensor element during assembly, leading to assembly failures and potential breakage of the sensor tip during sealing.

Innovation Solution

A method involving the use of an element dummy with annular mounting parts and a sealing assist jig to ensure precise alignment and compression of ceramic powder compacts, preventing positional deviations and minimizing impact on the protective film, thereby ensuring reliable assembly and sealing of the gas sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If annular mounting parts are mounted from the end with opening for measurement gas introduction, then dimensional tolerance is accommodated, but protective film is damaged or peeled off

Engineering Contradiction:

Improvedimensional tolerance accommodationVSAvoidprotective film damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional mounting direction by introducing measurement gas from the lower end instead of the upper end, allowing annular mounting parts to be installed from the lower end where no protective film exists, thus avoiding film damage while maintaining dimensional tolerance accommodation

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent separates the gas introduction function from the traditional upper end location and extracts it to the lower end, enabling independent optimization of the mounting process without compromising the protective film integrity

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If annular mounting parts are mounted on pin member then detection element is inserted, then assembly is facilitated, but mounting parts slide out of place

Engineering Contradiction:

Improveassembly facilitationVSAvoidmounting part position stability

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent performs preliminary mounting of annular mounting parts on the detection element itself before final assembly operations, ensuring proper positioning is established early in the process and maintained throughout subsequent steps

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the detection element as an intermediary fixture that temporarily holds the annular mounting parts in correct positions during assembly, eliminating the need for separate pin members while maintaining positioning accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If powder compact is compressed for sealing, then hermetic seal is achieved, but sensor element tip may break

Engineering Contradiction:

Improvehermetic sealingVSAvoidsensor element tip integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent inverts the compression direction by applying force from the lower end upward through the annular mounting parts, distributing compression forces away from the vulnerable sensor element tip while achieving hermetic sealing of the powder compact

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses the mass and structural support of the annular mounting parts and detection element to counterbalance compression forces, preventing excessive stress concentration at the sensor element tip during the sealing process

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 method effectively prevents assembly failures due to positional deviations and reduces the risk of chipping or cracking of the sensor element during sealing, allowing for accurate and reliable assembly of gas sensors with a protective film intact.

Implementation Method 1

The sealing assist jig has a buffer performance against an impact exerted from vertically above

Methodology Applied

Scientific EffectImpact absorption: Damping

Data Source

PatentUS10190895B2Method for assembling gas sensor, and gas sensor assembly apparatus

Publication Date: 2019.01.29 NGK INSULATORS LTD

AI summary

A method for assembling a gas sensor includes fitting through holes of annular mounting parts with an element dummy disposed vertically and whose cross-sectional shape perpendicular is similar to that of a sensor element. The annular mounting parts are a plurality of parts including a ceramic powder compact. A tubular body is fitted with outer peripheries of the annular mounting parts, and then, the element is abuttingly disposed on an upper end of the dummy. Subsequently, the dummy is moved vertically downward to fit the through holes of the annular mounting parts with the element, thereby obtaining a workpiece. The workpiece is vertically inverted, and with the element tip being in contact with a sealing assist jig that has a buffer performance, the upper end of the uppermost annular mounting part is pressed vertically downward to compress the powder compact, thereby sealing an inside of the tubular body.