US2499823A - Spark plug and method of making the same - Google Patents

Description

Patented Mar. 7, 1950 UNITED s'rA'rEs PATENT oEFlcE SPARK PLUG AND METHOD 0F MAKING THE SAME Adalbert J. Gogol, Maumee. Ohio Application May 2l, 1945, Serial No. 594,859 4 Claims. (Cl. 12S-189) This invention relates to spark plugs.

This invention has utility when incorporated in ignition devices, more particularly for holding or holding and sealing an insulator in the shell of a spark plug.

A maior problem in spark plugs is to provide an eillcient seal between the ceramic core and shell. The metallic shell and the insulator mounted therein have widely varying coefficients of expansion which must be compensated in order to prevent any leakage therebetween, leven under extreme conditions such as are encountered in present day aeroplane uses. The temperatures and pressures to which a spark plug is subjected while in use vary widely and, in order that the plug may be maintained gas-tight. the different expansion rates of the materials used in the plug must be compensated for.

Means may be used to compensate for the widely variable coefllcients of expansion of the different materials by employing a spring positioned between the insulator and the shell which ofi'ers a resilient means to compensate 4for these different expansions while the plug is in use and to maintain the required seal.

This invention contemplates the provision of a resilient member which is highly adaptable for this purpose, which is capable of being easily and economically manufactured and assembled in the production of the units and .which serves in a combination highly etllicacious for maintaining a satisfactory seal between the ceramic insulator and metallic shell of the spark plug or serving alone as the seal itself.

It is, therefore, ,a primary object of this invention 'to provide a resilient means positioned between the metallic shell v'and .the insulator of a spark plug which is capable of compensating for variations of expansion of the diil'erentmaterials used in the fabrication of the device so as to maintain a seal .between the under all operating temperatures to which the ,spark plug will be subjected during use in an internal co'mbustion engine. even under the more extreme operating conditions. such as .are frequently encountered in high altitude and heavy load aeroplane engines.

It is a further object of this invention to provide a resilient means for use between the insulator and shell of a spark plug to maintain a seal therebetween which is suiliciently flexible to prevent localization of breaking stresses upon the insmewr andauow equalization thereof-to obviate any injury such as a fractur'eof the 'insulator due to changes of temperatures 'or pressures to-wiiich 2 the plug may be subjected and to absorb and compensate for such regardless of the rapidity of variations of each or o! any combination thereof.

Still another object of this invention is to produce a spark plug inherently embodying the desirable qualities of a seal and compensating means in various plug types and employing economical base materials easily acquired in abundant quantitles and fabricated by ordinary skill.

Other objects and advantages of this invention relating to the arrangement, operation and function of the related elements of the structure, to various details of construction, to combinations of parts and to economies of ,manufactura will be apparent to those skilled in the art upon consideration of the following description and appended claims. reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Referring to the drawings:

Fig. 1 is a longitudinal section of a spark plug embodying one form of the invention disclosed herein; v

Fig. 2 is a view similar to Fig. l but showing the insulator core in elevation;

Fig. 3 is a longitudinal section, in part, of a modified construction of a plug embodying a form of the invention;

Fig. 4 is a plan view of a type of mesh material suitable to be employed in one way of forming a mat or bushing to be used between the spark plug core and shell;

Fig. 5 is a perspective view, partly broken away, of a type of mat or self-sustaining resilient ring which may be formed from the material of Pig. 4:

Hg. 6isaviewsimilartoi'1g.4,showinga 'swatch of mesh material wherein its strands are on a bias or diagonally interwoven; and

Fig. 7 is a' showing of a fragment of knit wire textile especially suitable in forming a self-sustaining rilient packing.

Referring to the drawings. particularly to Figs. 1 and 2, a metallic shell Il is provided with an externally-threaded portion I2 extending from shoulder Il of the shell. This externally-threaded portion is adapted to cooperate with an engine block (not shown), in which the plug is positioned during operation. The shell is provided with the usual polygonal portion il for convenient manipulation in positioning the spark plug in an engine block. Herein. extending from the `lower end of and across the axis of the threaded portion I2 is ground electrode il, a center electrode 2l to form -spsrk gap 2. 'While :,coaaaa l ceramicinsulator 24, and is of the alumina or other type, and extends therethrough in a central bore 26 having an intermediate seat 28, :against which collar 30 of the electrode 20 may rest for longitudinal positioning of the electrode in the This electrode may be sealed in position in l core. the center bore in any convenient manner, as,

for example, by a powder pack 82 or the like. The insulator core 24 is provided with an externally enlarged portion 38 providing shoulders 38 and 48. 'Ihe lower shoulder 88 is adapted to rest upon 15 an internal seat 42 within the shell I0 inter" mediate its length. In this type of construction, a gasket 44 is preferably positioned between the shoulder 88 and the seat 42 as a seal therebetween.

This gasket may be of nickel, soft iron, an alloy, 20

or other suitable material.

The upper end of the electrode may have electrical communication within the core with a contact terminal 46 which has threaded connection` 49 with the core and extends outwardly therefrom 25 and coniigured in any desirable form to receive a connection from an ignition circuit.

The shell ill extends upwardly beyond the shoulder 40 to provide an annular chamber 48 about the core for receiving a iiexible mat or bushing 58.v This packing 50 is flexible in all directions, and is conveniently formed by compacting a mass, or from a convolved mesh strip 52. In the formation of the member 50, layers of a. foraminous material may be rolled to form a ring or cylindrical body of dimensions to ll the chamber 48. A vsuitable material is a wire or y other heat-resisting material, mesh or screen of a comparatively line weave. When the multi-ply bushing is formed, it can be wound into a tight expansion of this highly resilient wad which securely locks it in the chamber. Following this assembly, ring- 54 is placed against the exposed or upper edge of the mat and the upper perimeter 5S of the shell lli is spun or peened thereover,

thereby again compactingthe mat and rmly of mesh material, wholly or partially loaded with holding its mass in position.

Even with thisl compacting, the bushing remains resilient, holding the seal gas-tight entirely about the shoulder 38 and compensating for any The bushing may not only serve as a spring.

cooperating with the ring or gasket 44 to form a seal, it may provide the complete seal itself. Such a construction is found of value in many instances. For example, in a plug of the type wherein the insulatorv core is of practicallyconstant diameter throughout, and its maior portion 84 (Fig. 3) or the chamber 88 is of another forni .or capacity. This latter type plug is devoid of any shoulder seal and the core portion 84 may be of a constant diameter through the chamber 88 and so extend therebeyonrl.v This core maybe of any longitudinal exterior outline as desired but, for convenience, is herein shown as cylindrical with a packing 88v completely filling the chamber 88,

In the bushing construction, it may be desirable to provide a treated packing such as a. tlller for the interstices therein. When the matting is formed, or the screen material is wound, the resulting cylinder may be compacted or crushed to gether by external forces from all directions wherein all symmetry of the mesh is lost and a body is formed replete with minute labyrinths. These irregular chambers may be nlled with an inert substance such as talc, a ceramic powder, or graphite, and such ller may or may not be treated as with an oil, a, polymerized oil, or a drying oil, for example, tung, linseed, Perilla or China oil. The ller may furthermore be composed of any combination of these materials as the ultimate use to which the plug is designed may dictate or require for the most efllcient operation. In the production of these bushings, the base mesh material may be wholly or in part coated with the inert material 10. either alone, or treated with an oil 12. 'I'he coating may be over the entire mesh, or either the inner or intermediate wraps, and the oil may be applied with the coating or subsequently applied by coating or immersion of the cylinders or the .packed plugs therein.

It has also been found the packings may be, to meet certain conditions, loaded with plastics sueh as of the Bakelite type or with silicones, or these materials are used as binders for the ilbers employed.

The .bushings are formed by direct packing of a massof the material or from layers or wraps the dry or treated filler and then compacted by squeezing into a highly resilient mass wherein the strands of-the mesh are contorted into a non-uniform mass, thereby forcing the nller and all changes due to expansion between the 55 throughout to illl the `multiple interstices. Such body parts of the plug and defeating any localization of stresses. In the bushing formation, as by matting a mass of thread-like material, or by convolving a continuous strip of mesh, the remass is packed directly into the chambers o1' the plug-or is compacted to a size for ready insertion into the plug for assembly. The ring 54 may then be inserted and compression therefrom silient form may be of a pattern forming cylinoo against the mass in the ilnal assembly by peendrical insert 50 having rims 58, 60 to more or less interilt with the cross-sectional shapes of the chamber as deilned by the shell and the insulator walls. This promotes a more complete packing in the finished plug. The base material 52 may 65 be a mass oi' `wires or a right-angle wovenwire mesh, providing square or rectangular interstices. or it may be a material 62 having a bias weave, either warp or Woof, or both, diagonally ing or spinning the edge 56 reshapes the bushing into a chamber packing, tightly, yet resiliently gripping the insulator core and providing a sate isfactory plug seal.

When the plug has been packed with a treated Wad, it may then be allowed to dry at ordinary temperatures, or heated to a degree of heat which may even be of a magnitude and duration to produce a curing c tect on some of the matericrossing the strip extent. Or the bushing may be als or that will polymerize any of the oils used.

made of layers of mesh having different gauges and weaves, so that an insert may be formed, not only to nt in any type of plug, but to meet any and all working conditions for which the plug isdesigned.

The bushing, which either serves asa spring in connection with other sealing means, either alone or loaded, may be economically produced and assembled. and cooperates withother plug v parts to form a superior product.

An especially desirable packing material is a wire textile" (Fig. 7) which may have a knit body either strip or tubular in form and is readily collapsed into a chamber or into a self-sustaining ring 59 for insertion into a chamber. The rings 59 may be reinforced by a suitable foraminous or other material 16.

The materials used for the packing may be combined with such heat-resisting threads or fibers 18 as asbestos, glass or the like.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the d'etails of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended t limit the scope of the 'following claims beyond the requirements of the prior art.

What is claimed and it is desired to secure by United States Letters Patent:

1. In a spark plug, a metallic shell having an internal chamber provided with a seat therein, an insulator having a center electrode and an enlarged external portion disposed in the chamber cooperating with said seat and forming an annular chamber with the shell above the enlarged portion, a deformable gasket cooperating between the enlarged portion and said seat, a preformed resilient mat of metallic fibers conformed to fit the annular chamber between the insulator and the shell and positioned therein, and an inturned lip on the shell to cooperate with one end of the resilient mat to urge the mat and the enlarged portion of the insulator against said seat to coin the deformable gasket and to resiliently hold the enlarged portion thereagainst through the resiliency of the mat to form a seal with the seat.

2. In a spark plug, a metallic shell having an internal chamber provided with an inwardly extending seat, an insulator having a center electrode and an enlarged external portion defining a pair of shoulders, said enlarged portion disposed in said chamber vwith the lower shoulder cooperating with said seat and the upper shoulder providing an annular chamber formed between vthe insulator and the shell chamber. a deformablegasket positioned between the lower shoulder and the seat adapted to be coined therebetween, a preformed resilient mat of metallic fibers conformed to nt the annular chamber and adapted to be positioned therein to resiliently hold the lower shoulder against the gasket to form a seal, and means on the shell to cooperate with the resilient mat to form an anchor for the mat whereby the resiliency thereof acts against the upper shoulder of the insulator.

3. In a spark plug, a metallic shell having an internal chamber provided with a seat therein.

an insulator having a center electrode and an enlarged external portion disposed in the chamber cooperating with said seat and forming an annular chamber with the shell above the enlarged portion, a deformable gasket cooperating between the enlarged portion and said seat, a preformed resilient mat of metallic fibers conformed to fit the annular chamber between the insulator and the shell and positioned therein, an inturned lip on the shell to cooperate with one end of the resilient mat to urge the mat and the enlarged portion of the insulator against said seat to coin the deformable gasket and to resiliently hold the enlarged portion thereagainst through the resiliency of the mat .to form a seal with the seat, and an inert filler for the resilient mat to fill the interstices thereof to aid in sealing.

4. In a spark plug, a metallic shell having an internal chamber provided with an inwardly extending-seat, an insulator having a center electrode and an enlarged external portion denning a pair of shoulders, said enlarged portion disposed in said 'chamber with the lower shoulder cooperating with said seat and the upper shoulder providing an annular chamber formed between the insulator and the shell chamber, a deformable gasket positioned between the lower shoulder and the seat adapted to be coined therebetween, a preformed resilient mat of metallic fibers conformed to fit the annular chamber and adapted to be positioned therein to resiliently hold the lower shoulder against the gasket to form a seal, an inert filler for the resilient mat to fill the interstices thereof, and means on the shell to cooperate with the resilient mat to form an anchor for the mat whereby the resiliency thereof acts against the upper shoulder of the insulator.

. ADELBERT J. GOGEL.

REFERENCES CITED The following references are of record in the ille of thisy patent:

UNITED STATES PATEN'IS Number Name Date 854,400 Brooke May 21. 1907 1,012,031 Underwood Dec. 19, 1911 1,052,170 Peterson Feb. 4, 1913 1,084,543 Furber Jan. 13, 1914 1,210,193 Mosler Dec. 26, 1916 1,286,384 Merger Dec. 3. 1918 1,349,454 Heath Aug. 10, 1920 1,999,785 Rohde Apr. 30, 1935 2,225,105 Flynt Dec. 17, 1940 2,238,396 Rabezzana et al. Apnl, 1941 2,248,415 Schwartzwalder et al. July 8, 1941 2,251,211 Armstrong July 29, 1941 2,252,496 Dutterer Aug. 12, 1941 2,275,085 Michel et al. Mar. 3, 1942 2,308,968 Gregory Jan. 19, 1948 2,356,102 Tognola Aug. 15, 1944 2,367,445 Btoltenberg Jan. 16, 1946 FOREIGN PATENTS Number Country Date 683,054 France June 5. 1930

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