US1155515A - Spark-plug. - Google Patents

Description

SPARK PLUG.

APrjyQAUON FILED 11111124. 1913` Patented 00115, 1915 x ALBERT SCIMIDT, OF FLINT, MICHIGAN, ASSGNGR TO UNITED STATES PATENT operon.

onnivrrron renrrron coureur,

0F FLINT, MIOHIGAN,=A CORPORATION F MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented lot.. 5, itali.

Application filed July 24, 1913. n Serialo. 780,565.

useful Improvements in Spark-Plugs, of

which the' following is a specifica-tion, reference being had therein tothe accompanying drawings.

The invention relates to spark plugs, and

lhas more particular reference to the means for securing the insulators in the.' metallic casing.

In the drawings: Figure l is'va central longitudinal section through the plug; and Fig. 2 is a perspective view of some of the parts detached. l

A isa metallic casing provided `with a hexagonal portion B and threaded nipple C.

D is a bushing having a threadedengagement with an internally threaded portion of the casing A," and being provided with a tapering or conical bore.

E is an insulator formed with a shoulder F for bearing against a complementary shoulder G upon opposite sidesv of said shoulder an upwardly-tapering portion H and a downwardly extending portion I of reduced diameter.

It is one of the objects of the invention to provide means for holding the insulator within the casing by a bearing 'of considerable ext-ent. Such a bearing performs the double function oi distributing the stress upon the insulator and also of forming a heat conducting medium for absorbing the heat of the insulator and dissipating the saine. To this end the tapered bore of the bushing D ispreferably complementary to the tapering portion ofthe insulator. Instead, however, of forming a direct engagement between the bushing and insulator, an inner bushing- J is lirst sleeved'upon the insulator, this being preferably made of n softer metal than the bushing D and forming a bearing surface on the insulator. Preterably I form the bushing` of aluminum.

vthe burning gases, will be conducted in the casing and also having rhis metal' is sufficiently soft and pliable and also possesses a high degree of heat conductivity.

In assembling the parts, the insulator E is placed in the casing A, with a gasket or packing K interposed between the shoulders F and G. The bushing upon the tapering portion' oft the insulator,

4after which the bushing D is engaged therewith and turned in the threaded portion of the casing A. This will draw the bushing J downward upon the insulator, and at the same time will press the shoulder F toward the shoulder G, compressing the gasket and forming a gas tight seal. By reason or' the extended surface of the bushing the pressure on the insulator is distributed and is comparatively slight at any one point, while at the same time this extended surface rapidly absorbs the heat of the insulator and conducts it into the bushing D and casing A. As a result, the heat absorbed by the inner end of the insulator, which is in contact with through the portion I of reduced diameter, enlarged portion, and from the latter be' dissipated through the bushing and wall of the casing.

IVhat I claim as'my invention is:

l. A spark plug, comprising an outer casing havinga threaded nipple, an internally threaded outer portion and a shoulder bearing therebetween, an insulator having a p0rtion Within vvthe nipple portion and an .enlargement fornnng a shoulder opposed to the shoulder on the casing and a portion tapering outward from said shoulder, a

bushin0F havinff a threaded en `a ement with J is then sleeved into the l the internally threaded portion of said casy' ing and a tapered bore, andan inner sleeve or bushing of substantially the length of said last mentioned bushing interposed between said last mentioned bushing and the tapering portion of said insulator forming an extended surface in contact with each and f ka heat conducting medium therebetween.

2. A spark plug, comprising a casing, an insulator therein having an enlargement formhg a shoulder opposed to n eomplerst-mentioned tapering bushingr to `form .1 10 nlentmy Shoulder on the casing, and tapersent and heabconducting medium.

ing' olitwud from Suid shoulder, n tapering In testimony whereof I affix my signature bushing surrounding said tapering portion in presence of two Witnesses.

of the 1115111211101' und hmjn? :L tllr'eaded en- ALBERT SCHMIDT gagement wlth the casmg, una :L second l tapering bushing ext-ending substantaly the Witnesses:

length of said 'i'sn1entio11ed tapering bush- B. DYNIUUARD,

ing, interposed between Suid insulator and "V. Gr. LA ROCK.

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