Insulator for the spark plug and the manufacturing approach thereof, together with the spark plug

Abstract

This invention provides a type of insulator for the spark plug and the manufacturing approach, together with spark plug, by which the product quality can be improved through an accuracy test on the products that determining whether a crack is happened during the manufacturing process. The insulator is manufactured by followed steps: I) Forming process. Shape the unsintered insulator that is in a set shape (compression and shape process, cutting process); II) Sintering process. Sinter the unsintered insulator. In addition, a crack detecting process is arranged between above two process. And the detecting process includes: 1) Examination liquid coating process, which is by means of coating penetrant examination liquid on the surface of the unsintered insulator; 2) Drying process, which is by means of drying the penetrant examination liquid on the surface of the unsintered insulator ; 3) Surface examineing process, which is by means of examining the surface of the unsintered insulator tofind out if any crack is occurred .

Description

technical field [0001] The present invention relates to a spark plug used in an internal combustion engine and the like, an insulator for a spark plug used for the spark plug, and a method of manufacturing the same. Background technique [0002] A spark plug is installed, for example, in an internal combustion engine (engine) to ignite the air-fuel mixture in the combustion chamber. Generally speaking, the spark plug includes: an insulator with a shaft hole; a center electrode inserted into the front end side of the shaft hole; a terminal electrode inserted into the rear end side of the shaft hole; a main body shell provided on the outer periphery of the insulator; A ground electrode that forms a spark discharge gap between the tip side and the center electrode. And, by applying a high voltage to the center electrode, a discharge is generated in the spark discharge gap between both electrodes, and the air-fuel mixture is ignited. [0003] In addition, the insulator constit...

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Problems solved by technology

[0009] However, in the case of using the inspection method of the above-mentioned Patent Document 2, if the crack is very small, the inspection liquid may not penetrate into the crack, and the inspection accuracy may be insufficient.

[0010] In addition, in order to prevent the deterioration of the appearance quality of the insulator, after the inspection, the permeability inspection liquid needs to be wiped off or evaporated, resulting in a decrease in manufacturing efficiency

In addition, it may be difficult to completely remove the inspection liquid that has penetrated into the fine unevenness of the insulator, and the inspection liquid may seep to the surface of the insulator over time, deteriorating the appearance quality.

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