Note: Descriptions are shown in the official language in which they were submitted.
1
SF~ARK PLUG WITH A RI1NG/OF~N~.RING SHAFED GROUND
ELECTRODE
This invention relates to a spark plug for an internal combustion
engine having a metal shell at least partially enclosing an insulator
the containing a conductive centre electrode, the centre electrode
having a bottom end exiting from the insulator at a bottom end of
spark plug, the bottom end off the eentre electrode being spaced
spar t Pram a ground electrode attached to the metal shell by at least
one support member.
Commercial internal combustion engine spark plugs in current wide
spread use have characteristically had a centre electrode with an
exposed end in its base that is spaced apart from a ground
electrode. The ground electrode is usually a single arm welded to an
edge of the plug and bent over towards the centre electrode at
substantially a right angle. Although these plugs work satisfactorily,
it has been determined that their design substantially detracts from a
complete burn cycle in an internal combustion engine's combustion
chamber. This results in the overheating of plug parts, incomplete
combustion and the production of oxides of nitrogen in the
combustion chamber.
Attempts at improving plug firing and achi.e~i.ng a more complete
combustion chamber burn has received little research effort compared
to other methods of reducing oxides of nitrogen automotive emissions .
U . S , Patent 2, 487, 535 describes an annular tapered curved f ork as a
spark plug ground electrode for the purpose of "conducting
excessive heat away". Column 1, lines 50-51. The central electrode
terminates in a position on a plane with the ground electrode sa that
the spark is substantially perpendicular to the longitudinal plane of
the spark plug. Such a spark geometry does not provide for a large
surface area to promote active combustion.
U . S . Patents 2, 874,162 and 4, 2~8, 774 describe ground electrodes
having diverging prongs. Such a configuration increases the spark
CA 02044622 1999-04-12
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surface area and improves combustion chamber burning. However,
substantial further improvement in burning efficiency in the combustion
chamber due to spark generation could be made.
In accordance with the invention, an internal combustion engine spark
plug has a metal housing at least partially enclosing an insulator
containing a conductive centre electrode. The centre electrode has a
bottom portion in the form of a solid cylinder with a planar surface at an
end distal from the insulator and extends from the insulator at the bottom
end of the spark plug. T'he bottom end of the centre electrode is vertically
spaced by about .89 to 1.22 mm from the ground electrode which is
attached to the metal housing. The ground electrode has an ring shaped
firing portion attached to the metal housing by at least one integral
mounting post, the ring shaped firing portion has a gap from zero to 2.5
mm. The top of the firing portion of the ground electrode is fixed at a
distance from and is positioned parallel to the bottom planar surface of the
centre electrode. The inner annular circumference of the ground electrode
is concentric with the centre electrode. The ground electrode inner
diameter is substantially equal to the exterior diameter of the centre
electrode and the firing pattern of the spark plug from the centre electrode
forms an annular ring pattern around the top of the ground electrode
firing portion.
In a preferred embodiment of the invention the inner diameter of the
ground electrode is from 1 to 1.1 times the outer diameter of the centre
electrode.
In a further preferred embodiment of the invention, the mounting post
for the ring shaped ground electrode is a substantially L-shaped supporting
bracket. In further preferred embodiment of the invention the ring shaped
ground electrode is attached to the metal shell of the spark plug by at least
CA 02044622 1999-04-12
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three spaced mounting posts.
It has been established that an uniform diameter ring shaped ground
electrode mounted to a mounting post attached to a mounting ring or spot
welded to a side of the spark plug produces multiple spark arcs around the
inner top surface of the ground electrode from the central electrode. These
multiple sparks result in a more complete fuel burning in the combustion
chamber and thereby an increase in engine horse power together with a
reduction of oxides of nitrogen emissions from the engine exhaust system.
The ring shaped ground electrode provides the maximal ignition area of
any possible ground electrode design. The tests prove that the spark plug of
the invention runs 10 to 15° cooler than standard plugs and that it
continues firing under more pressure per square-inch than any other
spark plug available on the market.
The invention may be best understood by those having ordinary skill in
the art by reference to the following detailed description when considered
in conjunction with the accompanying drawings in which:
4
Fig. 1 is an isometric view of one embodiment of the spark plug of
this invention.
Fig. 2 is an exploded view of the ground electrode component in
relation to the bottom of the spark plug of Fig . 1.
Fig. 3 is an isometric view of the ground electrode mounted within a
spark plug cup of the spark plug of Fig. 1. '
Fig. 4 is an isometric view of the ground electrode in the spark plug
cup of Fig. 3 showing the method of locking the ground electrode in
place.
Fig. 5 is a bottom plan view of the spark plug of Fig. 1.
Fig . 6 is an exploded view of an alternate ground electrode
component in relation to a spark plug cup.
Fig. 7 is an i$ometric view of the ground electrode component of Fig.
6 welded in place.
Fig. 8 fs an elevation view of the spark plug of Fig. 1.
Fig. 9 is an isometric view of another embodiment of the spark plug
according to the invention.
Fig. 10 is a bottom plan view of the spark plug of Fig. 9,
Fig. 11 is a plan view of a stamped blank of a ring/open-ring shaped
electrode and the attached mounting posts.
Fig. 12 is an elevation view of the ring/open-ring shaped electrode
and the attached mounting post realized with the stamped blank of
Fig. 11.
5
Throughout the following detailed description, the same reference
numerals refer to the same elements in all figures. The spark plug
has been shown in a base up position in the drawings fax ease of
description. However, the base is considered 1n its usual lower
position for purposes of the description that follows.
Spark plug 10 shown in );ig. 1 is a conventional internal combustion
engine spark plug except for the xing/open-ring shaped ground
electrode 12 substituted for the rod like ground electrode seen in
conventional spark plugs. The spark plug 10 shown in Fig. 1 has a
terminal element 14 Connected to a coil wire (not shown) . A high
quality insulator such as a cer amic material 16 encapsulates a central
electrode which terminates at the bottom of the spark plug 10 as
exposed central electrode 18, The ceramic material could be
substituted with a high temperature resistant copolymer. The bottom
portion of the spark plug 10 has a metal shell 20 and a nut portion
22. The shell 20 terminates in a shank 24 which has a shank skirt
26. The interior portion of the shank 24 is in the shape of a cup 28.
The centre electrode 18 is located in the centre of the cup 28. In
addition, the interior surface of the shank skirt 26 has an inwardly
protruding annular shelf 30.
The ground electrode 12 of the invention is ring/open-ring shaped
and has a gap 36 defined by two arms 32 and 36 having two
substantially parallel edges 36a and 36b. The distance between the
parallel edges 36a and 36b is of about 0 to .09$ of an inch or 0 to
2.~ mm. bistal from the gap 36 is a mounting post 3$ attached at a
first end 40 to the back end of the ring/open-.r9ng shaped ground
electrode 12 and at a second end 42 to a mounting ring 44.
In constructing the spark plug of the invention the ground electrode
component 46 consisting of the mounting ring 44, the mounting post
38 and the ring~open-ring shaped electrode 12 is preferably cast
frpm a high quality metal such as a nickel/chromium alloy, platinum
alloy and the like. The sharp right angle 48 of mounting post 38 is
important to enhance the spark qualities to be discussed hereafter.
6
The ground electrode component 46 is dropped on top of shelf 30 as
shown in Fig. 2 with the spark plug 10 in an inverted position.
Notches 50 are vertically cut in the edge 52 of shank skirt 26. The
metal sections 54 between notches 50 are bent or crimped as shown in
Fig. 4, over the mounting ring 44 to insure a fixed mounting position
of the component 46 within the bottom of the spark plug 10. The
distance 60 between the ground electrode 12 top surface 56 and the
bottom surface 58 of centre electrode 18 is ,035 to .o1,5 of an inch ar
p.89 to 1.22 mm. See Fig. 8. Greater or lesser spacing may be
required for combustion chambers of unusual design or fuels
substituted far gasoline such as propane, methanol or ethanol.
Upon firing, the electrical spark moves from the centre electrode 18
along the top surface 56 of electrode 12. The angle of the spark from
electrode 18 to the top surface 5f of electrode 12 is less than thirty
degrees and preferably is less than fifteen degrees from the
longitudinal axis of the spark plug .
The ring/open-ring shaped ground electrode 12 of the invention will
generate six to eight firing patterns so that the flame spread around
the periphery of the ground electrode is enhanced. Such an uniform
flame spread produces up to twenty percent added horsepower for a
given amount of fuel and approximately three to six miles per gallon
increased fuel economy. In addition, there is a reduction of twenty-
five to thirty-five percent in hydro-carbons and a reduction in
carbon monoxide, carbon dioxide and oxides of nitrogen in the
exhaust gasses. As a further advantage, the spark plug life is at
least doubled aver a conventional spark plug since the distribution of
the spark along the arms 32 and 3l~ prevent the single type burn
which occurs an a conventional ground electrode. Combustion
chamber smoulder time is reduced more than 50 %.
py casting the electrade 12, greater variability in the metal usage
can be achieved to obtain the optimum longevity of the electrode 12.
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Alternatively, the wlectrode 12 can be stamped o«t or ground ont
from a piece of m~~.al.
An alternative embodiment of the invention ie shown in Fi~a 6 and 7
wherein the mounting ring 44 is not used and the ~roun~i electrode
12a is merely mounted nt a right angle 48a to a mountins post 38a
which is spot welded to the edge 52a of a spark plug skirt 26a at the
second end 42a. The first end 40a of post 38a is attached to the
back end of Around electrode 12a.
The spark plug of Fibs 9 and 10 comprises a ground electrod~~
component 46 consisting of the rin~/open-rind shaped ground
electrode 12 and three mounting posts 70 which are welded on the
end surface of the shank skirt 26. Preferably the number of
mounting posts 70 is three but this number may be decreased or
increased.
According to the embodiment shown by Fi~a. 11 and 12, the
component 66 is stamped out from n metal plate an3 the free end
portions 71 of the mounting posts are slightly curved to be located in
a plane parallel to the plane of the ring/open-ring ahape3 ground
electrode.
The improved spark plug of this invention can be used in
conventional internal combustion engines for automobiles, boats,
r.irplanes, ia:~n-mowers and like articles ef manufacture. It also
improves horsepower ir, dual plug cylinders and in combustion
chambers with enhanced turbulence.
