US 936507 A
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Description (OCR text may contain errors)
J. G. ANDERSON.
APPLICATION FILED MAILZO, 1909.
936,507. Patented Oct. 12,1909.
.UNITED STATES PATENT OFFICE.
James C. ammnson, or wasnme'ron, ms'rmc'r or comniiam.
'- Specification of Letters Patent.
Patented Oct. 12, 1909.
' Application filed March 20, 1909. Serial No. 484,725.
To all whom it may concern:
Be it known that I, JAMES C. ANDERSON, a citizen of the United States, residing at WVashington, in the District of Columbia, have invented certain new and useful Improvements in Spark-Plugs; and I do hereby d hire the followin to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which 'itappertains to make and use the same.
My invention relates to certain new and useful nnprovements. in spark-plugs, particularly of that type shown and described in -Letters Patent granted to me July 7 1903,
No. 732,812, in which the central electrode.
and easing are insulated by glass, welded to the electrode and casing.
My present invention has for its object to produce. a spark-plug which shall be simple and economical of construction, and which shall be devoid of the possibility of short-circuiting by reason of the presence of carbon, oil or moisture deposited on, or between the electrodes.
lVith these ends in view, my invention consists in the details of construction and arrangement hereinafter more fully set .forth.
In'order that those skilled in the art to which my invention appertains may know how to make my improved spark-plug and fully appreciate its advantages, I will pro-' oeed'to describe the same, referring by numorals to the accompanying. drawing in which: c
Figure l is'a central longitudinal section of a spark-plug embodying the features of my invention; Fig. 2 is an' inner; endview of the same; Fig. 3 isa view similar to Fig. 1', and illustrating "a modification of the same. Fig. *li's a'detail section of the construction shown at Fig. 1, and on enlarged scale to more fully illustrate the relation of the electrodes andthe insulation; and
Fig. 5 is a similar enlarged sectional view :of the modified construct-ion shown at Fig. 3. ike
Similar reference numerals indicate parts in the severalfigures of thedrawing'.
, 1,' represents the casing, and 2, the positive '50.
stereos insulated from one another by a body'ofglass, 3, welded tothe casing and the electrode as. fully set forth in theLetters Patent hereinbefore referred to.
J f-Th shelhlllj clearly shown in Figs. 4
' integral head which constitutes the negative 5, terminates at itsinner end in a thin chamber in a vertical direction.
electrode 4. This head or negative electrode is formed with an opening 5, the edge of which surrounds, and is at sparking distance from the positive electrode 2, and also with a series of openings 6, between ,the central opening 5 and the periphery of the shell.
The insulatin lass 3 enters these 0 enin 's 6, and terminates flush with the outer surface of the electrode, while it terminates at the locality of the opening 5, coincident with the inner surface of said electrode, as shown at Fig. 4, or with the outer surface, as shown at Fig. 5, as may be preferred. The perforati'ons or openings 6 in the negative electrode are provided in order that the flash of the explosionwithin the explosive chamber of an engine may be readi y observed from without.
In Fig. 3, I have shown a modification in which the head, or negative electrode 4, is of concave'd form, which may be desirable when the spark plug enters. the explosive In this modified construction, it will be seen that the positive electrode where it passes through the central opening 5 projects slightly .beyond the outer exposed surface of the negative electrode, and hence should any lubricating oil or moisture accumulate upon the exposed endof the positive electrode, or
between itand the negative electrode, it will be led to gravitate toward the extremity of theelectrode, and sparking will then, take place above such obstruction and until the heat generated will evaporate or dispel the same.
In either of the constructions shown, it will be seen that the negative electrode surrounds the positive electrode and is at all oints at the minimum sparking distance mm the positive electrode, and that the insulating body at the particular locality at which the sparking takes place is coextensive only with the sparking gap or are be"- tween the electrodes.
and customary to make the superficial area of the exposed surface-of the insulating material as great as poss1ble within the-limits wall ofv the shell, again ,by extending the central electrode and the surrounding in- At this point I wish to state that it'has heretofore been desirable sulation beyond the inner extremity of the shell, or by forming a. cavity in' theinsulabe depositedupon the surface of the insulacleansing or Wiping action of such spark, and expels or dissipates any short circuitouter surface of the negative electrode, the
tion and between it and the central electrode, thus as stated securing the greatest possible distance from one extremity to the,other of 5 the exposed surface of the insulation. My invention on the contrary involves the generic feature of reducing the distance over the exposedsurface of the insulation to the minimum and at the locality at which the sparking occurs in order that any short cirj cuitingbody which may be deposited upon the surface lof the insulating material will be dispelled or evaporated by the heat generated by the sparl As shown in the drawing, the insulating material 3 which is welded with the shell 1, and positive electrode 2, presents a surface at the particular locality at which the sparking must take place, coextensive with the sparking gap between the electrodes, and this sparking gap is preferably of minimum extent in order that the spark may be of the greatest intensity, in order that itm'ay overcome and dispel the comparatively feeble conductivity of any short circuiting substance which may be deposited in the gapor are between the electrodes, and hence operate to expel or remove the same, and thus preserve continuous and uninterrupted sparking.
When the insulating body 3 extends only to, and in the same plane'with the inner surface of the negative electrode 4, the sparking takes place within the circumferential space between it and the positive electrode 2, and hence the surface of the insulating material coincident with the inner surface of the negative electrode is subjected to the ing medium. Likewise if the insulating material extends to, and coincident with the spark will jump from the positive to the negative electrode and over the insulating material, and in a similar manner dissipate any short circuiting material which might tion.
I wish it to be understood that'the generic and underlying feature of my invention resides in the fact that the insulating'material at the particular locality at which the sparking takes place is coextensive only with i the sparking gap or are between the two electrodes, or in other words, the two eleci trodes are so arranged that one completely 3 surrounds the other at uniform and minimum sparking distance, and that the entire circumferential area of the insulation between the electrodes is such, that the flash from the central electrode to the surround- I ing electrode simultaneously and uniformly traverses the entire surface of the insulating material 3, and consequently the entire surface of this insulating material is kept free I from the presence of any short-circuiting body, and this is what is meant by the statement that the area of the insulating material between the electrodes is coextensive with the sparking gap or are between the two electrodes. This condition is secured as illustrated in the drawing by reducing or attenuating the inner extremity of the electrode 2, in order that when the surrounding electrode 4, is brought into minimum sparking distance with the former, the entire circumfcrential area of the insulating material between the two electrodes is such that the flash will be uniform and simultaneous in every radial direction, and hence sparking cannot take place at any one radial point while shorl-circuiting material may be deposited at some one or more other ,radial localities.
In other words, the extreme diameter of the insulating material surroundln the central electrode is coextensive with the sparking gap or are between the electrodes. \Vhile the relation between thetwoelectrodes and the insulating material at the locality where the spark occurs is .designedly such that the spark occurring will be a ring spark and trend. in all radial directions simultaneously, it will also be understood, that this described relation of the electrodes and the insulating surface is such, that if for any unforeseen reason the spark should cease to be a ring-spark, and should travel in a single radial line from the central electrode to the surrounding electrode, and moisture or other short-circuiting body be deposited upon the insulating material either side of the sparking ath, the entire superficial area of the insu' ation is so limited as not to provide surface sufficient for the deposited moisture &c. to overcome the natural sparking between the electrodes. I have taken pains to reiterate this feature of construction in order that there may be no doubt as to this generic feature of my invention, as I consider it of the utmost importance. While I prefer to arrange the positive electrode centrally within the insulating material between it and the shell or casing, I desire it to be understood that'I do not wish to be confined to this particular construction, as the positive electrode may pass through a surroundin spark gap or opening in the inner end 0 the shell at any other locality, so long as the relation between the electrodes and the body of insulating material is such as described that at the particular locality at which the place, the spark must traverse the entire surface of the insulating material and 0perate to keep such surface free from the presence of any short-circuiting medium.
Having described the construction, op-
eration and advantages of my improved what I claim as new and desire,
spark plug to secure by Letters Patent is:
' insulatin 1. A spark plug embodying in its ora shell having its inner end re-- ganization, turned at an angle to its axis to constitute one of its electrodes; a second electrode longitudinally disposed within the shell and terminating-in reduced and attenuated form within sparking distance from the surrounding returned end of the shell; and a body of shell an the longitudinally disposed electrode and in contact with the returned end of the shell and bridging the space between it and the longitudinally disposed electrode.
2. In a spark plug such as described, a shell returned at its inner end at an angle to its axis, and formed with a perforation or orifice therein; an electrode longitudinally disposed within the shell and terminating in attenuated form, and at sparking distance from the boundary of the perforation or orifice in the returned end of the a body of insulating material confined between the shelland the longitudinally disposed electrode and brid ing the annular space between said electrot e and the boundmaterial confined between the shell; and
ary of the perforation or orifice in the returned inner end of the shell, and in substantial contact therewith.
' 3. In a spark plug such shell returned at its inner end at an angle to its axis to constitute one electrode; a second electrode longitudinally disposed within the shell and terminating in attenuated form, and at sparking distance from the returned inner end of the shell; and an insulating body of glass occupying the entire space between theshell and the longitudinally disposed electrode, and Welded to said electrode and shell and'in substantial contact with'theinner end of the latter and bridging the sparking space between the shell and the electrode.
In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.
. I JAMES C. ANDERSON. Witnesses:
D. G. STUART,
HEnRY C. HAZARD.
as described, a