US1511199A - Spark plug and method of making the same - Google Patents

Description

Oct. 7 1924.

1,511,199 A. GHAMPION ET AL SPARK PLUG AND METHOD OF MAKING THE SAME Filed April 14 1921 Patented Oct. 7, 1924.

UNITED STATES PATENT" OFFICE.

AIIBERT CHAMPION, OF FLINT, AND LLOYD BLACKMORE, OF HIGHLAND PARK, MICHIGAN, ASSIGNORS TO A C SPARK PLUG COMPANY OF DETROIT, MICHIGAN,

A CORPORATION OF MICHIGAN.

SPARK PLUG AND METHOD OF MAKING THE SAME.

Application filed. April 14, 1921. Serial No. 461,237.

To all whom it may concem:

Be it known that we, ALBERT CHAMPION, a citizen of the United States, and resident of Flint, Genesee County, Michigan, and LLoYo BLAOKMORE, a subject of the King of Great Britain, and resident of Highland Park, Wayne County, State of Michigan, have invented certain new and useful Improvements in Spark Plugs and Methods of Making the Same, of which the following is a full, clear, concise, and exact description, such as will enable others skilled in the art to which the invention relates to make and use the same, reference being made therein to the accompanying drawings, which form a part of this specification.

Our invention relates to spark plugs of the type or class commonly referred to as single piece plugs, because of the fact that after the insulator of the plug has been assembled with and secured in place within the shell or casing of the plug the parts cannot be disassembled without destroying the plug; thus providing a plug the insulator of which cannot be removed by the user with a resulting impairment of the gas tight qualities of the lug, as it is diflicult if indeed not impossi le after having removed the insulator from the casing to replace it in such a way as to prevent leakage of gas through the joint between the parts.

More specificall stated, our invention relates to and the ohject thereof is to provide an improved shell or casing for spark plugs of the type or class above referred to; said improved casing being one which may be more readily and cheaply manufactured than has heretofore commonly been the case, with a resulting reduction in cost of the finished shell and of the plug of which it forms a part. 4

\ A further object of our invention is to provide an improved spark plug shell or casing made from sheet metal stock by subjecting the same to suitable forming,

drawing-shaping and similar operations, as distinguished from forming the same from solid bar or rod stock, as has heretofore commonly been the cas I A further object of our invention is-to provide an improved form of shell or casing for single piece spark plugs of the type above referred to.

A further object" of our invention is to provide an improved method or process of making shells or casings for single piece spark plugs; and a still further object of our invention is to provide an improved single piece spark plug and an improved method or process'of making the same.

With the above and other objects of invention in view, our invention consists in the improved single piece spark plug and method of making the same, and in the improved spark plug casing or shell and method of making the same illustrated in the accompanying drawing and hereinafter described and particularly claimed; and in such variations and modifications thereof, within the scope of the concluding claims, as will be obvious to those skilled in the art to which my invention relates.

In the drawing accompanying and forming a part of this application and wherein the referred embodiment of our invention is il ustrated:

Figure 1' is a view partly in section and partly in side elevation showing a single piece spark plug the shell or casin of which is made in accordance with on invention.

Figures 2, 3 and 4 are views showing three distinctive conditions assumed by the piece of metal from which the upper or outer section of the plug casing is formed, as the same is subjected to the various manufacturin steps or operations whereby it is produced.

Figures 5, 6 and 7 are views similar to Figures 4 to 6, but showing the lower or inner section of the casing at three distinct sta es of its manufacture.

eferring shell or casing of ourimproved single piece spark plug is made up of an outer section 8 substantially tubular in form,and having an inwardly extending ledge 9 at its upper end overlying the upper shoulder 10 of the porcelain or equivalent insulator 11 of the plug, and an inner substantially tubular section 12'having a shoulder 13 adjacent its upper end for supporting the lower shoulder 14 of the insulator; the meeting ends of the two sections bein joined along a joint at 15, preferabl by e ectrically welding the meeting ends 0 the sections together. The

to the drawing, the externalinner casing section is threaded upon its periphery so that the plug may be screwed into athreaded spark plug opening in an engine cylinder, and the exterior surface of the upper casing section is shown as octagonal in form so that the plug may be screwed into place by a suitable wrench.

In making the plug illustrated in Figure 1 the tubular casing sections are placed over the insulating member as shown, suitable gaskets being ordinarily placed between the ledge 9 and shoulder 10, and between the ledge 13 and the shoulder 14; and the assembled plug is inserted between pressure applying jaws or clamps of an electrical weld ing device designated conventionally by the letters -A and ,B and which are connected with a source of electricity, so that the parts may be pressed together while a welding current is caused to flow through the contacting surface at the abutting ends of the casing sections thus electrically welding the sections together along the joint 15. At the same time the pressure applied to the casing sections to accomplish the welding I compresses the gaskets referred to to a degree proper-to secure gas tight joints -be- -tween the insulator and the casing, the movement of the sections toward one another resulting in a slight upsetting at the abutting edges as shown; so that the act of electrically welding the contacting ends of the easingtogether secures also the necessary'gas tight joints between the casing and the insulator located therein.

The substantially tubular casing sections 8 and 12 may be made from pieces of tubing cut to proper length and shaped to provide the flanges 9 and 13 by the use of suitable dies, or made otherwise in accordance with approved manufacturing processes. In Figures 2 to 7, however, we have shown these members as formed from discs of sheet or thin plate metal stock by the use of suitable shaping, drawing, cutting and other appropriate operations; thus providingfor the making of the parts of the shell or casing and, as follows, the complete casing of the plug from sheet metal stock; which enables the shell to be made at slight cost, and with a minimum waste of material.

Thus Figure 2 shows a cup-shaped mem: ber 16 made from a fiat circular disc of metal by forcing it the proper number of times through suitable drawing dies by the use of suitable plungers; and Figure 3 shows the cup after it has been forced through dies of proper form to impart an octagonal form to the side wall 17 and to the peripheral surface thereof, and after the end wall 18 of the cup has been partially shaped to provide the inwardly extending holding ledge 9 hcreinbefore referred to. Thereafter, and after such further shaping operations as may be necessary to impart the proper form to the section being operated upon, the central portion of the end wall 18 is removed as by a suitable punch and die; thus providing an opening 19 through which the upper end of the insulating member 11 extends, and leaving the inturned ledge 9 in the form necessary to hold the insulator in place within the shell when the sections thereof are assembled and welded together as hereinbefore explained.

By subjecting a sheet metal disc of proper diameter to suitable drawing, forming, shaping, punching and equivalent steps the same may be made to assume the cup form 20 shown in Figure 5; then the form shown in Figure 6 with the offset supporting flange or shoulder 21 adjacent the upper end thereof; and finally, after the head 22of the cup has been punched out, to assume the form shown in Figure 7 which is that of the finished lower or inner casing section; the threads shown in said figure having been cut by a separate operation and the shoulder 21 having been smoothed up or otherwise finished, when such a course is deemed necessary, to provide the supporting shoulder 13 adjacent the upper end of the said lower or inner casing section.

While as herein explained it is necessary in the manufacture of spark plugs in accord ance with our invention that the pressure applied to the tubular casing sections be maintained while their free edges are being welded together, in order that the tight joints thus produced between the insulator and the portions of the sections which hold Y the same in place within the shell shall persist, and be maintained in the completed plug so that leakage of gas past the joints will be prevented, it is not essential that the welding shall be of the character commonly implied by the term and in which there shall be no metal at the joint other than the metal of the sections themselves; as we intend in some cases to accomplish the Welding by running in or ama'lgamating a. third metal at the joint in accordance with methods of weldin wherein parts are joined wholly or in part y a Wire, strip, ori otherwise shaped piece of metal fused adjacent the joint to be formed, and permitted to run in between the parts to be joined together.

Having thus described and explained our invention, we claim and desire to secure by Letters Patent:

1. The method of making a spark plug which consists in assembling an insulating member within two tubular casing sections having free edges adapted to engage one another, and each of which sections is provided with holding means adapted to on ago said insulating member and hold it in ace within the casing formed by said to ular members; applying pressure to said tubular members to force them toward one another;

and welding the free edges of said casing sections together while the force applied to said members is maintained. I

2. The method of making a spark plug which consists in assembling an insulating member within two tubular casing sections having their free meeting edges in contact, and which casing sections are so formed as to grasp said insulator and hold the same permanently within the casing formed by said casin sections; and simultaneously forcing sai sections toward one another and weldin their abutting edges together.

3. T e method of making a spark plug which consists in assembling an insulating member within two tubular casing sections havin their free meeting edges in contact,

and w ich casing sections are so formed as to grasp said insulator and hold the same permanently within the casing formed by said casing sections; and simultaneously forcing said sections toward one another and cansing a welding current of electricity to flow through the oint at their contacting ed s.

4. The method of making a spark p ug shell or casing which consists in assembling two tubular casing members or sections so formed as to receive and support an insulator in line with one another, with their ends in contact; and welding the abutting ends of said casing members to ther.

5. The method of making a spark shell or casing which consists in forming two cup-shaped members from sheet metal, and properly shaping said members and removmg the end walls thereof to thereby provide two tubular casing'members or sections; as-

. sembling said casing members in line with plug one another and with theirends in contact; and welding the abutting ends of said casing sections together.

6. In a sparkplug, two tubular casing members or sections having abutting ends welded together; and an insulating member located within the casing thus formed.

7. In a spark plug, two tubular casing members or sections having abuttin ends welded together; supporting means ocated within one of said members; holding means carried by the other of said members; and an insulating member located within the easin thus formed and held in place between said supporting and holding means.

8. A spark lug comprising a shell or casing made up of two tubular casing members arranged in line, and the abutting ends oi which are welded together; and an insulat ing member permanently held in place within said shell.

9. A spark plug comprising a shell or casing made up of two tubular casing members arranged in line with one another and th abutting ends of which are welded together; a supporting shoulder located within said casing and adjacent the joint between said casing members and in one of said members; an inturned holding flange located at the .free end of the other of said casing members; and an insulating member located within said casing and permanently held in place between said supporting shoulder and said-inturned flange.

In testimony whereof we aiiix our signatures.

ALBERT CHAMPION. LLOYD BLACKMORE.

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