Spark Plug Insulator Charge Neutralization for Sealing Layer Consistency

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Solution Overview

Problem

The existing method for manufacturing spark plugs often results in a protruding peripheral edge of the first sealing layer due to electrical adsorption on the insulator's inner wall, leading to inconsistent resistance values among products.

Innovation Solution

A method that includes a charge adjusting step to neutralize the insulator and electrically conductive glass powder before filling, preventing electrical adsorption and ensuring a consistent shape of the first sealing layer, which involves positioning the center electrode, filling with conductive glass powder, resistor composition powder, and sintering to form the sealing layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulator is charged by friction during transportation, then the electrically conductive glass powder is electrically adsorbed on the inner wall of the insulator, but the peripheral edge of the first sealing layer significantly protrudes toward the proximal end after sintering

Engineering Contradiction:

Improveconsistency of resistance valuesVSAvoidprotrusion of peripheral edge

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent applies preliminary action by introducing a charge neutralization step before filling the shaft hole with electrically conductive glass powder. This preliminary action removes static charge from the insulator surface, preventing the subsequent electrical adsorption of powder particles that would cause irregular protrusion and resistance value inconsistency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of static electricity (which causes powder adsorption and shape irregularity) into a beneficial process by using charge neutralization. The static charge that would normally cause problems is actively removed, transforming the situation from harmful to beneficial, ensuring uniform powder distribution and consistent sealing layer shape.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If the peripheral edge of the first sealing layer protrudes significantly, then the manufacturing process is simple, but the resistance value becomes inconsistent among products

Engineering Contradiction:

Improvesimplicity of filling processVSAvoidconsistency of resistance values

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The charge neutralization step is performed as a preliminary action before the simple filling process. This maintains the ease of manufacture by keeping the filling operation itself simple, while the preliminary charge removal ensures that the resulting sealing layer has consistent dimensions and resistance values, thus improving manufacturing precision without significantly complicating the overall process.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the electrically conductive glass powder is filled into the charged insulator, then the filling operation is quick, but the powder is electrically adsorbed on the inner wall

Engineering Contradiction:

Improvespeed of filling operationVSAvoiduniformity of powder distribution

Core Design Contradiction:

ProductivityVSShape

Solution Approach 1:

The patent performs charge neutralization as a preliminary action that is quick and does not significantly slow down the filling operation. By removing the static charge before filling, the powder particles are not electrically adsorbed on the inner wall, ensuring uniform distribution and consistent sealing layer formation while maintaining high productivity.

Inventive Principle:

Principle #10Preliminary action

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

This approach prevents the peripheral edge of the first sealing layer from significantly protruding, ensuring consistent resistance values and reducing variability among spark plug products.

Implementation Method 1

a charge adjusting step for placing at least one of the insulator and the first electrically conductive glass powder in an uncharged state or placing the insulator and the first electrically conductive glass powder in the same charged state

Methodology Applied

Scientific EffectElectrostatics: Electrostatics

Implementation Method 2

a sintering step for sintering the first electrically conductive glass powder, the resistor composition powder, and the second electrically conductive glass powder in the shaft hole

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS10985535B2Method for manufacturing spark plug with peripheral edge of proximal end surface of sealing distal-end layer prevented from significantly rising toward proximal end

Publication Date: 2021.04.20 DENSO CORP

AI summary

In a method for manufacturing a spark plug, a space on a proximal end side of a center electrode in a shaft hole of an insulator is filled with first electrically conductive glass powder. A space on the proximal end side of the first electrically conductive glass powder in the shaft hole is filled with resistor composition powder. A space on the proximal end side of the resistor composition powder in the shaft hole is filled with second electrically conductive glass powder. The first electrically conductive glass powder, the resistor composition powder, and the second electrically conductive glass powder are sintered in the shaft hole. Prior to filling of the resistor composition powder, at least one of the insulator and the first electrically conductive glass powder is placed in an uncharged state, or the insulator and the first electrically conductive glass powder are placed in the same charged state.