Spark plug with increased durability

A technology of spark plugs and ceramic insulators, applied in the field of spark plugs, can solve the problems of broken ceramic insulators, cracks, damaged wire covers, and more expensive pulling out.

Inactive Publication Date: 2006-03-08
DENSO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Negative pressure or vacuum is thus created inside the wire shield, so more force is required to pull the wire shield out of the spark plug
If the wire shield is pulled under force, it can result in damage to the wire shield or its breakage or cracks on the ceramic insulator

Method used

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  • Spark plug with increased durability
  • Spark plug with increased durability
  • Spark plug with increased durability

Examples

Experimental program
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Embodiment Construction

[0034] Referring now to the accompanying drawings, especially figure 1 , which shows a spark plug for an automotive internal combustion engine according to a first embodiment of the present invention.

[0035]The spark plug 1 roughly includes a hollow cylindrical metal shell 2 , a ceramic insulator 3 , a center electrode 4 and a ground electrode 5 . The ceramic insulator 3 is held within the metal case 2 to have an insulator head 31 extending outside the metal case 2 toward the base end side (ie, the upper portion as viewed in the drawing) of the spark plug 1 . The center electrode 4 is held in a center hole 32 formed in the ceramic insulator 3 . The ground electrode 5 extends from the metal casing 2 and faces the center electrode 4 through a spark discharge gap 14 .

[0036] The metal shell 2 has a thread 21 and a hexagon head 22; the thread 21 is used for installation in the internal combustion engine, and a wrench will be fitted on the hexagon head 22 to install or remove...

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PUM

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Abstract

A spark plug is provided which is designed to be compact without sacrificing a mechanical strength of a porcelain insulator. The spark plug includes a metal shell having a base end and a top end. The porcelain insulator is made of a hollow cylinder which includes a body and an insulator head. The body is retained within the metal shell. The insulator head extends from the base end of the metal shell in a lengthwise direction of the porcelain insulator and has a length made up of a major body leading to the body of the porcelain insulator and an end portion lying far away from the body. The major body has an outer diameter D 1 , an inner diameter D 2 , and a section modulus Z at a smallest-outer diameter portion thereof which meet relations of 7.1 mm<=D 1 <=8.8 mm, D 2 >=2.8 mm, and Z>=33 mm<3>.

Description

technical field [0001] The present invention relates generally to improved durability spark plugs for internal combustion engines that may be used in automobiles, combined heat and power systems, or air supply pumps. Background technique [0002] Internal combustion engines used, for example, in automobiles utilize spark plugs to ignite an air-fuel mixture. For such spark plugs, it is increasingly required to improve the combustion in the engine in order to reduce fuel consumption or its exhaust emissions. Improvements in the combustion require improvements in the engine's thermal efficiency and compression ratio, however, this can lead to autoignition of the mixture in the combustion chamber of the engine, thus causing engine knock. [0003] The engine knock can be reduced by improving the cooling system such as a water jacket, which is arranged around the piston head to enhance the cooling of the engine. [0004] In order to improve the performance of the engine and the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01T13/20
Inventor 阿部信男川岛泰后藤常利
Owner DENSO CORP
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