US1135727A - Spark-plug. - Google Patents

Description

- A. SCHMIDT.: l SPARK PLUG.

Llcmon FILE 1,135,727. V' A PatentedApr.3,191-5. l

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A TTOH/VEY I UNITED sTATEs PATENT oFFIoE.

ALBEBT SCHMIDT, F FLINT, MICHIGAN, ASSIGNOB TO CHAMPION-IGNITION COMPANY, 0l" FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr. 13, 1915.

' Application led May 29, 1914. Serial No. 841,744.

To all 'whom t may concewuyy Be it known that I, ALBERT SCHMIDT, a

citizen of the Republic of France, residing useful Improvements in Spark-Plugs, of

which the following is a specification, reference being had therein to the accompanying drawings.

In the present state of the art in the manufacture ofy spark plugs, it is usual to incase the insulator member in a metallic bushing which is threaded for engagement withthe engine cylinder` These elements aresecured together so as to form a gas-tight seal, but when the plug is in use in an engine cylinder and is subjected to the heat developed by the internal combustion, it frequently becomes leaky. -This is due to the fact that the coeiicient of expansion of the metal is much greater than thatA of the porcelain or insu-L lator, so that there is a loosening of the joint therebetween. It is one of the objects of the present invention to maintain a leak-proof joint between the metal and the porcelain by initially forming said joint when the metal is heated to a temperature equal or in excess of any temperature to which it is subsequently subjected.

It is a further object to obtain a simple and expeditious method of forming the joint, and a simple and inexpensive construction of plug as hereinafter set forth.

Inv the drawings: Figure 1 is a longitudinal section through a spark plug showingl vthe metallic bushing and insulator in engagement, but 'before the sealing joint is formed; Fig. 2 is a view lillustrating the method of'heating the metal and fashioning the same to form the clamping joint; Fig. 3 isa similar view after the completion of l the joint; and Fig. 4 is anvelevation of the completed plug.

A is the metallic bushing provided with the usualthreaded nipple B, and which is formed with a main bore and a counter-bore with a shoulder kC therebetween.

D is a comparatively thin annular flange at the upper end of the counter-bore.

E is the insulator which has an enlargement F for seating upon the shoulder C within the counter-bore of the plug.y

To secure theinsulator within the sleeve with a gas-proof seal, these parts'are first Apreferably comparatively on and simultaneously an endw'ise pressure the electrodes. This will reheating the metal of bushing,

isl applied toi sult, first, in

the most intense heat being in the comparatively thin flange or n D, but the body portion of the bushing being also heated to a high temperature. The pressure of the die J will then fashion the fin into a bead which is pressed against the.`

gasket H, conforming exactly to the contour of said gasket and conforming the latter exactly to the contour of the insulator so' as-to produce a gas-tight seal. The plug' thus formed will remain gas-proof regard,

less of the heat to which 1t is subjected in use, for this heat can never 'equal that to which the metal was subjected when the sealing joint was formed.

Another advantage resulting from this method of forming the seal is that the metal -being in a plastic condition is free fromjresiliency and will more perfectly conform to the-contour of the porcelain than is possible with the cold metal.

What Iclaim as my invention is 1. The method of uniting metallic bushings and insulators of spark plugs, comprising the placingof the insulator in the bushing, the heating of the metal of the bushing to a -temperature'equal to or in excess o that to which it will be subsequently subjected in use, and the compression of the metal to form the sealing joint while thus heated. f

2. The method of uniting the metallic bushings and insulators of spark plugs, com-v prising the heating of the metal and the fashioningfof' -the same while hot into conformity to the insulator to form a gas-tight seal therewith.

3. The method of uniting metallic bushings and insulators of spark plugs, comprising the heating of the metal to atempera- 4. The method of uniting metallicbush-Y ings and insulators-of spark pllgs, comprising the placing of the insulator in the bushing, placing a compressible gasket upon said insulator, heating the 4bushing to a temperature at which the metal is plastic, and' compressing the metal while hot to conform vthe same to said gasket and the insulator.

- 5. The method of uniting metallic bushings and insulators of spark plugs, comprising the formation ofthe bushing with a thin ange, the engagement of the insulator with said bushin vthe engagement of the bushing with an e ectric Welder toheat the metal, and the application .of pressure while the metal is hot to conform the thin flange to the contour of the insulator.

6. The method .of uniting the metallic bushings-with the insulators of spark plugs, comprising the placing of the vinsulator in initial engagement with the bushing, the engagement of the bushing between electrodes of an electric Welder, one of said electrodes being of die form, and the a plication of pressure when the metal o .the

bushing is hot to conform the sameto the contourn of the insulator.

7 A spark plug, comprising an insulator and a metallic bushing forcibly conformed bly conformed to and contracted upon said insulator.

9.l A sparkplug, comprising an insulator,

and a metallic bushing having an integral portion thereof hot-fashioned and forcibly contracted upon said insulatorto form a sealing joint therewith.

10. A spark plug, comprising an insuvlator, having an enlargement, and a metallic bushing provided witha shoulder on ywhich said enlargement is seated and having an integral portion hot-fashioned and forciblyl contracted upon said enlargement to form a sealing joint therewith.

In testimony whereof I aix my signature in presence of two witnesses.

ALBERT SCHMIDT.. Witnesses:

. Loms CHENOLEY, B. O. YINCHARI

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