US1529853A

US1529853A - Spark plug

Info

Publication number: US1529853A
Application number: US503637A
Authority: US
Inventors: Thoma William Chris
Original assignee: Individual
Current assignee: Individual
Priority date: 1921-09-27
Filing date: 1921-09-27
Publication date: 1925-03-17
Anticipated expiration: 1942-03-17

Description

March 17, 1925.

W. C. THOMA SPARK PLUG Filed Sept. 27, 1921 Patented Mar. 17, 1925.

WILLIAM CHRIS THOMA, QF LAURENS, IOWA.

SPARK PLUG.

Application filed September 27, 1921.

T0 all-whom c't may concern Be it known that 1, WILLIAM CHRIS T-HOMA, acitizen of the United'States, and

V resident of Laurens, inthe county of Pocahontas and State of Iowa, have invented a certain new and useful Spark Plug, ofwhich the following is a specification.

This invention relates to improvements in sparkplugsin which the insulating member is'atorined of a series of transverse layers of mica or similar insulating material bound together'by means-of longitudinally extending rods. Insulating members constructed in thismanner are Vlyefilclellll as long as the edges of thelayers are-kept free from oil, but when the insulators are used in cylinders in which a considerable amount of oil is used, the spaces between thelayersbecome saturated with oil and shortcircuiting results be tween the longitudinally extending terminal member andthe casing of the spark plug in which the insulatoris-mounted. This is due to the tact that-the space'between the layers of mica become filled with conducting substances which enter the spaces between the discs or layers of material.

One of the objects of my invention is to overcome the above difficulty by providing means whereby the-cylindrical face of the insulating member may be absolutely protected against oil from coming into engagement therewith.

A further object is to provide in a spark plug having an insulating member formed of a series of adjacent discs of insulating material, new and improved means for mounting the insulating member within the casing of the spark plug in such a manner that the circumferential edges of the discs will not be exposed to oil or similar substances.

A further object is to provide in a spark plug improved arrangement of spark terminals and the manner in mounting the same.

A still further object is to provide improved means for mounting the insulating member within the casing of a spark plug.

These and other-objects will'be apparent to those skilled in the art.

My invention consists in-the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in any claims,

Serial No. 503,637.

and illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of my improved spark plug.

Figure 2 is a longitudinal sectional view of'the same taken on the line'a'2 of Figure 1. I

Myimprovedspark plug comprises a casing 10,-the upper endof :which' is provided with a hexagonal 'nut "11, and the lower end of whichis provided with a screw threaded portion 12.

The casing lOis-provided with a centrally arranged cylindrical opening 13. *The upper end of the opening 13 is provided witha screw threaded portion 14:,tllQlOlVQI' end of the casing is provided with a cylindircal opening 15 of a slightly less diameterthan the opening 13 so that a slight'inclined 'inwardly extending shoulder 16 is provided. The lower end of the opening 15 is provided with an inwardly extcnding flange l7, the inner edges of which form an opening 18. Theportion 12 is of standard diameter and provided with standard thre-ads.

The insulatingineniber'19 of my improved spark plugis perferably formed of ,aseries of discs of mica and laid adjacent to each other and bound together by means ofcentrally located conductor rods-20.

These rods 20 are spaced a slight-distance apart and have their upper ends screw threaded and extending througha plate 21, and each provided with anut 22.

The plate 21 is formed il-shaped so that the upper portion of said member 21 lies above the nuts 22 and is pro videdwitha terminal screw 23. Abe said sci'ew'is-provided with the usual terminal nut 2% so an ranged that connection inay be made between a suitable conductor wire and the plate'Ql.

The lower ends of the rods :20 extend downwardlythrough the lower end of the insulating member 19, and are provided with collars 25 which rest adjacent tothelower end of said member 19,thereby providing means whereby the discs of said -member may be rigidly clampedbetween the collars 25, andtlie plate 21 forming the ncmber 19 into a rigid insulator.

The central portion 26 of the insulator l9 is formed cylindrical and of a diameter slightly less than the diameter of the opening 13 and designed to rest in said opening when in its normal position.

The upper end of the member 19 is formed slightly conical, the lower end of the conical member being of a less diameter than the member 26 to form a shoulder 27.

The shoulder 27 and the adjacent portion of the member 19 is provided with a conical sleeve 28 having an outwardly extending flange 29, the flange 29 being designed to rest on the shoulder 27, and the portion 28 being designed to snugly fit the lower end or" the conical portion. 7

A screw threaded bushing 30 is provided and designed to coact with the screw threadedportion 14. The said bushing is provided with a hexagonal nut 31 and with a conical opening 32 designed to fit the outer surface of the member 28, while the inner end of the bushing 30 rests against the flange 29. The opening in the bushing, however, is loose enough so as to permit the said bushing to rotate freely on the sleeve 28. This forms means whereby theinsulator may be secured in the casing as will hereinafter be made clear.

Adjacent to the lower end of the cylindrical portion 26, I have provided a smaller cylindrical portion 33, and adjacent to the lower end or the cylindrical portion 33, I have provided a downwardly extending conical portion 34, the upper end of the conical portion 34 being of less diameter than the portion 33 to form an annular shoulder 35.

The diameter of the portion 33 is slightly less than the diameter of the opening 15, while the diameter of the lower end of the conical portion 34 is of a diameter substantially equal to the diameter of the open-V ing 18.

Mounted upon the portion 33, I have provided a shell 36 of thin sheet metal having a number of annular and outwardly extending beads 37, and at its lower end an annular and inwardly extending flange 38. The inner edge of the flange 38 is designed to Test against and overlap the lower end of the insulating member 19.

The space between the shell 36 and the conical portion 34 is filled with asbestos or some other insulating, heat-resisting material 39. In assembling the shell 36 the member 39 is placed adjacent to the portion 34,

then the shell 36 is placed over the member 39 and the said casing squeezed longitudinally onto the member 33. This will cause the member 39 to be packed and squeezed to a very condensed condition so as to positively engage the ends of the .discs torming the portion 34, and thereby form an oil tight joint to prevent the oil from seeping between the discs.

After the shell 36 has been squeezed into position, the .upper edge of said shell is spun into the cylindrical portion 33, as s own at 40, so as to prevent the said shell from moving out of position due to the ex pansion of the material within.

By this arrangement, it will be seen that I have provided an insulating member comprising the member 19, the shell 36 and the packing 39 in a unitary form whichmay be removed or placed in the casing 10 when so desired. The beads 37 are of such diameter that they will be squeezed into position as the member 19 is moved downwardly into the opening 15, and as they engage the in clined shoulder 16, thereby forming a tight joint between the beads and the wall of the opening 15 to prevent oil from entering the space between the portions 26 and 33 and the walls of the opening 13. 7

To further assist in preventing the oil from working upwardly between the insulating member and the casing 10, I have provided a packing washer 41 which is similar to those used in spark plugs.

The packing 41 is placed between the flange 38 and the flange 17. NVhen the bushing 30 is screwed into the casing 10 the said flanges will be moved toward each other and engage the packing 41, thereby forming a tight joint.

By making the bushing 30 loosely mounted on the sleeve 28, the said bushing may be screwed into position and the insulator clamped without rotating the said insulator and destroying the contact between the packing 41 and the adjacent flanges, the beads 3? and the adjacent wall. By forming the sleeve28 so that it tightly fits the member 19, the portion 28 of the said sleeve will be made to carry a portion of the force applied by the bushing '30, and to distribute the said force to a large number of discs of the member 19 rather than applying all of the pressure to the shoulder 27 as has been done heretofore. lVhen all the pressure is applied to the shoulder 27, it causes the disc adjacent to the bushing 30 to be sprung downwardly and a fracture or opening will result between the lower end of the conical portion and the upper end of the cylindrical portion 26. By providing the conical sleeve 28 the pressure is applied substantially uniform to all of the discs and no fracture will result.

The lower ends of the members 20 are curved slightly inwardly toward each other to form a spark gap. A ground member 42 is provided, the lower end of which is spaced member of which dinary spark plug as I find it gives better results.

By this arrangement, it will be seen that I have provided a spark plug, the insulating may be formed of mica or similar material and so arranged that oil or similar substances will not enter the space between the discs. The insulating member may be easily and quickly removed from the w casing when so desired, for cleaning and renewing. It will also be seen that I have provided improved means whereby the said insulator may be effectively and efliciently secured in the casing without destroying or breaking down the discs of the insulating member.

I claim as my invention.

1. A spark plug comprising a casing having a cylindrical opening at its central portion, the inner end of said opening being provided with an inwardly extending flange, an insulator formed of a series of adjacent and transversely arranged disks, said insulator being provided with an enlarged cylindrical portion designed to fit the upper end of the opening of said casing having an upwardly and outwardly extending end and a downwardly extendinocylindrical portion, the lower end of whici is formed conical, a packing member for the conical portion of said downwardly extending end, means secured to the downwardly extending cylindrical portion for securing said packing in position, means for securing said insulator member within said casing, a conductor member for said insulator, and a ground member for said casing placed in operative relation with each other.

2. A spark plug comprising a casing having a clyindrical opening in its central portion and a smaller cylindrical opening adjacent to one end, the inner end of said smaller opening being provided with an inwardly extending flange, the outer end of said larger cylindrical opening being screw threaded, an insulator formed of a series of adjacent and transversely arranged disks, said insulator being provided with a cylindrical portion designed to fit the larger opening of said casing, the lower end of said insulator being provided with a smaller cylindrical portion and a smaller conical portion, a packing member for covering the last said conical portion and means for securing said packing member thereto, a conductor extended longitudinally through said insulator, a terminal screwed to the upper end of said conductor, a ground conductor in operative relation with the first said conductor, a screw threaded bushing designed to coact with the screw threaded portion of said casing and to secure the insulator in position.

3. A spark plug comprising a casing having a cylindrical opening at its central portion and a smaller cylindrical opening adjacent to one end, the inner end of said smaller opening being provided with an inwardly extending flange, the outer end of said larger cylindrical opening being screw threaded, an insulator formed of a series of adjacent and transversely arranged discs, said insulator being provided with a cylindrical por tion designed to fit the larger opening of said casing, and with a conical upwardly extending end, a sleeve for said upwardly extending conical portion, a bushing for said sleeve, a conductor extending longitudinally through said insulator, a terminal screw for the upper end of said conductor, the lower end of said insulator being provided with a smaller cylindrical portion, and a smaller conical portion, a packing member for the last said conical portion, and means for securing said packing member thereto, a packing ring between the lower end of said insulator member and the annular flange of said casing, a ground conductor in operative relation with the first said conductor.

4. A spark plug comprising a casing, an insulator member mounted therein, a double conductor arranged longitudinally through the center of said insulator having the lower ends of its members bent slightly toward each other, a collar on each of said members spaced apart and designed to rest against the lower end of said insulator, the spacing of said collars being less than the spacing between the downwardly projecting end, a terminal at the upper end of said insulator member being connected to both of said conductors, means for securing said insulator in said casing, and a ground conductor in operative relation with the first said conductors.

5. A spark plug, a casing having a cylindrical opening at its central portion and a smaller cylindrical opening adjacent to one end, the inner end of said smaller opening being provided with an inwardly extending ange, an insulator formed of a series of adjacent and transversely arranged disks, said insulator being provided with a cylindrical portion designed to fit the larger opening of said casing and a smaller upwardly extending end, the lower end of said insulator being provided with a smaller cylindrical portion and a smaller conical portion, a packing member for the last said conical portion, means for securing said packing member thereto, a packing ring between the lower end of said insulator member and the annular flange of said casing, longitudinally through said insulator, a ground conductor in operative relation with the inwardly extending end of the first said conductor, means for detachably securing the insulator member within said casing.

Des Moines, Iowa, September 2, 1921.

WILLIAM CHRIS THOMA.

a conductor extended