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Патент USA US2139793

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Dec. 13, 1938.
j 2,139,793 ’
Filed June 15, 1936
Patented Dec. '13, 1938
Cecil B. Benton, Vergennes,’ Vt.
Application an. 15, 1936, Serial No. 85,201
3 Claims. ‘(or 123-469)
The inventionrelates to spark plugs.
The primary object of the invention is to pro
and a sleeve 22 of insulation between collar 2| and
ring [1.
The-ground contact 24 consists of a strip of vide an electrode on the shell of the plug, usually
the “ground” electrode which can be readily and metal extending across the cylindrical opening in
5 accurately deformed or varied‘ to provide the ‘. the inner end of shell ‘ ID, with its ends 25 seated 5‘
optimum gap for sparking and also shields the in recesses cut in the end of the shell and secured
sparking face on the center electrode from direct ther°ein by brazing or welding, as indicated at 26.
The central portion 21 of the strip 24'is offset
contact with the ?ame in the cylinder.
Another object of the invention is to achieve
longitudinally of the axis of the inner electrode
10 this primary object with a diversity of forms of . 12, being bent as at 28 between the portions'25 l0
electrodes, and with spark plugs for engines hav and 21. ' The inner face of o?set portion 21 forms
ing different output characteristics.
Other objects of the invention will appear from
detailed description.
the sparking face of the ground electrode. The
electrode 24 is shaped from a strip of ?at stock
and its central portion 21 is of su??cient width
or area to overlie the sparkingface l4 on the 15
The invention consists in the several novel fea
tures which are hereinafter set forth and are . central electrode l2 so it will shield the sparking
face I 4 of the central electrode from the'?ame.
more particularly de?ned by claims at the con
clusion hereof.
In the drawing:
r {"1
in the cylinder and prevent scouring of the spark
ing face I4 by such flame. The central electrode
12 is usually made of a spark-resisting alloy of 20
steel, because it is insulated from the shell and is
Fig. 2 is’ a section, on an enlarged scale, . thus not as well cooled by intimate contact with
through the electrodes and shell, ‘illustrating the the cylinder head. The electrode 24 is formed of
a metal, steel or alloy which is sui?ciently ductile
manner of resetting the electrode on the shell to
1'3 vary, and provide the optimum gap between the‘ or malleable so as to avoid any spring-action 25
i when it is deformed and so‘ that when it is im
sparking faces of the electrodes;
Fig. 3 is an end view of the plug illustrated in pacted by a tool, such as a suitable hammer, the
Fig. 1 is a longitudinal section of a spark plug
' embodying one form of the invention; ‘
Fig 1;
central portionj1 will remain set in its deformed
Fig. 4 is a section illustrating a. modi?ed form
;-'0 of the invention applied to a vcenter (‘electrode
used for a high output engine;
Fig. 5 is an end view of the plugillustrated in
Fig. 4;
Fig. 6 is an end. view embodying another modi
35 ?ed form of the outer electrode.
The invention is exempli?ed in. Figs. 1 to 3 in
shape with practically :no tendency to spring
back to its normal shape. This degree of ductility 30
‘or malleability may be attained by subjecting the _ 7
metal to_suitable heat treatment.v The heat ap
plied to the ends 25 of the strip, for welding or
brazing them to the shell, may be utilized to some
extent‘ for this purpose. The ground electrode 35
may be made-‘of spark-resisting ‘alloy; since it can
a spark plug comprising a shell II), which is pro- , :‘be separately formed from the shell or integrally
formed therewith. In either event, the material '
vided with the usual screw-thread for engaging a
corresponding internal thread in the engine cas
40 ing and with a polygonal ?ange ll whereby the
assembled plug may be screwed into the casing;
a center electrode l2 having a cylindrical termi-'
nal l3 at its inner end on which the ?at circular
_ sparking face I4 is formed; and a stem 9 extend
ing longitudinally through the plug; a sleeve l5_
of suitable insulation surrounding the stem 9
should be suf?ciently ductile ormalleable to elimi
nate any spring-action when it is deformed, com- 40
pressed or bent, and to cause it to remain set in
its adjusted position or shape.‘
When the gap between thesparking surfaces on
the electrodes becomes excessive from use or
wear, an ordinary hammer of suitable size may be 45
used‘to pound down the portion 21 of the strip
forming the electrode 24. A templet or strip a,
and engaged by a shoulder IE on electrode l2; a indicated by dotted lines in Fig. 2, of a correct
coupling ring l1 provided with a screw-thread I8 thickness to correspond to the optimum gap be
50 for engaging a‘ corresponding internal thread in tween the‘ electrodesfi may be inserted between 50
the shell l0 and‘ having a shouldered inner end them while the portion 21 of the strip forming
for engaging a gasket 20 and forcing it against a electrode 24 is hammered down to provide the
conoidal surface in the shell; a collar 2| ?xed to ' proper gap; On account of the softness or lack
the outer end of the stem 9 of electrode 12 and of spring in the metal forming the electrode 24,v
55 for electrical connection‘with a conductor wire; the central portion 21 will be set, as indicated 55
by dotted lines in Fig. ‘2, so that the sparking
- face on its inner side will be brought down to the
correct distance from the sparking face of the
center electrode, without resulting in any substan
tial recession of the sparking face on portion 21
from the strip a or the sparking face Id of the
inner center electrode. By hammering down the
entire central portion 21 and the use of 'a templet,
the normal parallelism of the sparking-faces,
10 which are perpendicular to the axis of the elec
trode I 2, will be retained. By forming the ground
electrode of metal which will remain set in the
positionkin which it is hammered, it makes it pos
sible to provide a spark plug in which the spark
16 ing faceof the center electrode is shielded by
the ground electrode to prevent direct contact
of the ?ame with the sparking face of the inner
electrode and to easily vary or adjust the sparking '
faces-for the correct or most e?lcient spark gap.
20' In the event that the gapbetween‘the sparking
faces of the electrodes is too small, after the elec
trode 24 has been applied, the gap may be in
creased by screwing out the assembly consistingr
' of the electrode I2, sleeves I5, 22 and ring ll’
25 slightly, inserting a templet a and then screwing
deformation of the metal while the central por
tion is being hammered to form the desired spark
The invention exempli?es a spark plug with an
electrode on the shell which shields the sparking
face of the central electrode from direct contact
with the cylinder ?ame and is‘readily and accu
rately variable to provide the optimum spark-gap. .
The invention also‘ provides for variation of the
spark-gap by hammering, which results in reset 10
ting or adjusting the metal'without spring-action.
The invention also provides for embodying these
features in ground electrodes'of different forms.
The invention also ‘provides a ground electrode
having these characteristics which provide for
recession of the spark-plug gap into the shell for
high output engines.
‘ .
The invention also provides a ground electrode
having, these characteristics which may be sepa
rately formed'from the shell, sothat they may be 20
made of spark-resisting metal, although it is to be
understood that in some instances the invention
may be applied to ground electrodes which, for
cheapness in manufacture, are integrally formed
with the shell.
'down the said assembly. Usually, use of the plug
The invention is not to be understood as re--_ ,
increases the gap and the adjustment required is_ stricted to the details setvforth, since these may
a decrease of the gap, which is done by hammering be modi?ed within the scope of the appended
the portion 21 of electrode 24, as before described. claims, without departing from the-spirit and
30 In low output engines, the diameter of the cylin
scope of the invention.
drical end l3 of the inner electrode is smaller
Having thus described the invention, what I
than the diameter used in high output engines. claim as new and desire to secure by Letters
In the modi?cation illustrated in Figsrfl and 5, Patent is:
the electrode 249- on the shell is made of metal
1. A spark. plug comprising a shell-provided
having the ductile and springless properties here
inbefore described and comprises a central por
with means whereby it may be secured to an
engine-casing, an inner electrode in the shell hav
tion 21*‘ of sufficient area to extend over the spark- ‘ ing a ?at sparking-face at its inner end, and a
ing face on. the large cylindrical .end I38 of the ?at strip forming a coacting electrode, bridging
central electrode i‘la of a spark plug fora high the inner end of the shell, formed separately ‘from
40 output engine. The ends ‘Mia of the strip 24‘1 are and having both of its ends permanently bonded 40
brazed or welded in recesses in the end of the shell to the shell and comprising an integral central
sea. In this modi?cation the electrode 24*‘ is nor
portion having a substantially ?at sparking-face
mally ?at and its entire ?at central portion is parallel with the sparking-face on the inner elec
adapted to be de?ected or hammered tdward‘the trode, said strip being formed of malleable or due
45 sparking face MB of the inner ‘electrode, as indi
tile metal which can be pounded or de?ected to- »
cated by dotted lines in Fig. 4,‘ so asto maintain Ward the sparking-face on/the inner- electrode to
parallelism between the sparking" surfaces. In vary the gap between the sparking-faces by de
'high output engines, it is desired to terminate the formation between its central portion and both of
central electrode inwardly of the end of the shell its bonded ends, so that the central portion will
50 as shown. In this case, the central portion 228- is remain set and maintain the parallelism ‘between
de?ected downwardly by a suitable hammer to the sparking-faces.
keep its inner face in parallelism with the spark
2. A spark plug comprising a shell provided with
ing face it“ and the metal between the central means whereby it maybe secured to an engine
portion and the end portions 25 is de?ected down
casing, an inner electrode in the shell having a
55 wardly and stretched, as indicated at 289-. While ?at sparking-face at itsinner end, and a ?at strip
‘this isdone a templet may be inserted between forming a coacting electrode, bridging the inner
the sparking faces of the electrodes to arrest and end of the shell, formed separately from, and
set the central portion of the strip the correct having both of its ends permanently bonded to
distance'from the sparking face I4“ and provide the shell and comprising an integral central por-,
the correct spark gap.
tion having a substantially ?at sparking-face 60
Fig. 6 illustrates a modi?ed form of ground parallel with the sparking-face on the inner elec
electrode of ductile or malleable metal having the trode and longitudinally extending portions be
same properties as those hereinbefore described tween the central portion and the bonded portion,
and which comprises a circumferential rim 30 said. strip being formed of malleable'or ductile /
which is brazed or welded, as indicated at 3!, to metal which can be pounded or de?ected toward 65
the shell ill"; a central portion 32 adapted to the'sparking‘lface on the inner electrode to vary
extend over and shield the sparking face on the the gap between the sparkingafaces by deforma
end of the inner electrode 82'’, and a series of tions in the longitudinally extending portions, so
connecting arms 33 between the annular portion that the central portion will remain set and main
30 and the central portion 3!. The central por
tain the parallelism‘between the sparking-faces.
tion 32 may be de?ected by a hammer, as herein
3. A spark plug comprising a shell provided- '
bei‘ore‘described, when the sparking faces are to with means whereby it ‘may be secured to an
be brought together to compensate for wear. In engine-casing, an inner electrode in, and ter~
tphis form of the invention the arms 33 are offset minating inwardly of, the shell having‘ a ?at
75_adja‘cent_the annular portion 30 to permit the sparking-face at its inner-end, and a transversely 75
straight ?at strip forming a coacting electrode,
electrodeto vary the gap between thesparking
‘ bridging the inner end of the shell, formed sepa
faces by deformations between its central portion
rately from and having both of its ends perma
nently bonded to the shell and comprising an and both of its bonded ends, so that the ‘central
integral central portion having a. substantially
?at sparking-face narallel with the sparking-face
on the inner electrode, said strip being formed of
malleable or ductile metal which can be pounded
portion will remain set and maintain the paral- B
lelism between the sparking-faces.
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