SPARK PLUG WITH A OPEN-RING SHAPED GROUND ELECTRODE

Description

[0001] 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 of the centre electrode being spaced apart from a ground electrode attached to the metal shell by at least one support member.

[0002] 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.

[0003] Attempts at improving plug firing and achieving a more complete combustion chamber burn has received little research effort compared to other methods of reducing oxides of nitrogen automotive emissions. A known spark plug is provided with an annular tapered curved fork as a spark plug ground electrode for the purpose of "conducting excessive heat away". The central electrode terminates in a position on a plane with the ground electrode so 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.

[0004] U.S. Patents 2,874,162 and 4,268,774 describe ground electrodes having diverging prongs. Such a configuration increases the spark 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.

[0005] EP-A-0 167 687 shows a spark plug having a ground electrode in the shape of an open round frame concentrically arranged above a centre electrode. The inner diameter of the open round frame is greater than the diameter of the centre electrode, so as to create a sloping type discharging pattern.

[0006] It is an object of the invention to provide a spark plug with an improved ground electrode generating significantly increased spark between the ground electrode and central electrode to thereby increase burning in the combustion chamber and resulting in increased engine horse power per litre of fuel, reduced oxides of nitrogen emissions and extended spark plug performance.

[0007] According to the invention the spark plug is characterized by the features of independent claim 1.

[0008] The gap has two parallel edges or two radial edges. The distance of the edges of the gap range from 0 mm to 2,5 mm. The at least one support member is a reversed L-shaped supporting bracket. One leg of the reversed L-shaped supporting bracket is located in the plane of the open-ring shaped ground electrode. The open-ring shaped ground electrode is attached to the metal shell by at least three spaced support members.

[0009] According to an embodiment of the invention, the open-ring shaped ground electrode may be integral with and at a sharp right angle to at least one support element, the support element being integral with a mounting ring at an end distal from the ground electrode, the mounting ring being in a plane parallel to the open-ring shaped ground electrode.

[0010] Preferably, the metal shell lower end is a shank skirt crimped over the mounting ring to hold the ground electrode in position or by welding .

[0011] According to an advantageous embodiment of the invention, the open-ring shaped ground electrode attached to the bottom of the metal shell, has an uniform diameter, encircling the centre electrode on a plane about 0.89 to 1.22 mm below the centre electrode, and a gap with parallel edges. The back end of the open-ring shaped ground electrode is integral at a sharp right angle with a first end of at least one support element, the support element being integral with a mounting ring at a second end. The metal shell has a bottom shank skirt with spaced apart notches on a lowest edge and an annular shelf on an inner surface, the mounting ring being crimped in place on the annular shelf by bending the shank skirt inwardly or by welding, and the gap is diametrically opposite to at least one support element.

[0012] It has been established that an uniform diameter open-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 open-ring 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 m² (square-inch) than any other spark plug available on the market.

[0013] The invention may be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjuction with the accompanying drawings in which whereby it should be noted that the spark plug is illustrative only and may be modified to include all features of the claims :

[0014] Fig. 1 is an isometric view of one embodiment of the spark plug.

[0015] Fig. 2 is an exploded view of the ground electrode component in relation to the bottom of the spark plug of Fig. 1.

[0016] Fig. 3 is an isometric view of the ground electrode mounted within a spark plug cup of the spark plug of Fig. 1.

[0017] 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.

[0018] Fig. 5 is a bottom plan view of the spark plug of Fig. 1.

[0019] Fig. 6 is an exploded view of an alternate ground electrode component in relation to a spark plug cup.

[0020] Fig. 7 is an isometric view of the ground electrode component of Fig. 6 welded in place.

[0021] Fig. 8 is an elevation view of the spark plug of Fig. 1.

[0022] Fig. 9 is an isometric view of an embodiment of the spark plug.

[0023] Fig. 10 is a bottom plan view of the spark plug of Fig. 9.

[0024] Fig. 11 is a plan view of a stamped blank of a open-ring shaped electrode and the attached mounting posts.

[0025] Fig. 12 is an elevation view of the open-ring shaped electrode and the attached mounting post realized with the stamped blank of Fig. 11.

[0026] 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 for ease of description. However, the base is considered in its usual lower position for purposes of the description that follows.

[0027] Spark plug 10 shown in Fig. 1 is a conventional internal combustion engine spark plug except for the 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 ceramic 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.

[0028] The ground electrode 12 of the invention is open-ring shaped and has a gap 36 defined by two arms 32 and 34 having two substantially parallel edges 36a and 36b. The distance between the parallel edges 36a and 36b is of about 0 to .098 of an inch or 0 to 2.5 mm. Distal from the gap 36 is a mounting post 38 attached at a first end 40 to the back end of the open-ring shaped ground electrode 12 and at a second end 42 to a mounting ring 44.

[0029] 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 open-ring shaped electrode 12 is preferably cast from 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.

[0030] 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 .045 of an inch or 0.89 to 1.22 mm. See Fig. 8. Greater or lesser spacing may be required for combustion chambers of unusual design or fuels substituted for gasoline such as propane, methanol or ethanol.

[0031] 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 56 of electrode 12 is less than thirty degrees and preferably is less than fifteen degrees from the longitudinal axis of the spark plug, when the ground electrode inner diameter is equal to the exterior diameter of the center electrode, as defined in claim 1.

[0032] The 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 1-2 km/liter (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 over a conventional spark plug since the distribution of the spark along the arms 32 and 34 prevent the single type burn which occurs on a conventional ground electrode. Combustion chamber smoulder time is reduced more than 50 %.

[0033] By casting the electrode 12, greater variability in the metal usage can be achieved to obtain the optimum longevity of the electrode 12.

[0034] Alternatively, the electrode 12 can be stamped out or ground out from a piece of metal.

[0035] An alternative embodiment of the invention is shown in Figs 6 and 7 wherein the mounting ring 44 is not used and the ground electrode 12a is merely mounted at a right angle 48a to a mounting 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 ground electrode 12a.

[0036] The spark plug of Figs 9 and 10 comprises a ground electrode component 46 consisting of the open-ring 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.

[0037] According to the embodiment shown by Figs. 11 and 12, the component 46 is stamped out from a metal plate and the free end portions 71 of the mounting posts are slightly curved to be located in a plane parallel to the plan of the open-ring shaped ground electrode.

[0038] The improved spark plug of this invention can be used in conventional internal combustion engines for automobiles, boats, airplanes, lawn-mowers and like articles of manufacture. It also improves horsepower in dual plug cylinders and in combustion chambers with enhanced turbulences.

Claims

1. An internal combustion engine spark plug (10) having a metal housing (20) at least partially enclosing an insulator (16) containing a conductive center electrode (18), which has a bottom portion (58) in the form of a solid cylinder with a planar surface at an end distal from the insulator and extends from the insulator at a bottom end of the spark plug, the bottom end of the center electrode being vertically spaced by about 0.89 to 1.22 mm from a ground electrode (12) attached to the metal housing,
characterized in that
   the ground electrode (12) has an open ring shaped firing portion (32, 34) attached to the metal housing (20) by at least one integral mounting post (38), said portion having a gap (36) of 0-2,5 mm,
   a top of the firing portion of the ground electrode is fixed at a distance from and parallel to the bottom planar surface of the center electrode (18),
   an inner annular circumference of the ground electrode is concentric with the center electrode,
   the ground electrode inner diameter is equal to the exterior diameter of the center electrode, and
   a firing pattern from the center electrode forms an annular ring pattern around the top of the ground electrode firing portion.

2. A spark plug according to claim 1, characterized in that the ground electrode (12) and the mounting post (38) is integral with a mounting ring (44), which is in a plane parallel to the ground electrode and vertically spaced by at least one mounting post (38).

3. A spark plug according to claim 2, characterized in that the metal housing (20) has a shank skirt (26) at the lower end crimped over the mounting ring (44) to position the ground electrode (12) over the mounting ring.

4. A spark plug according to claim 1, characterized in that the insulator (16) is a ceramic material.

5. A spark plug according to claim 1, characterized in that the inner diameter of the ground electrode (12) is from 1 to 1.1 times the outer diameter of the center electrode (18).

6. A spark plug according to claim 1, characterized by three mounting posts (70) attached to the ground electrode (12).

Ansprüche

1. Eine Verbrennungsmotorzündkerze (10) mit einem Metallgehäuse (20), das wenigstens teilweise einen Isolator (16) umgibt, der eine leitende Mittelelektrode (18) enthält, die einen Bodenabschnitt (58) in Form eines Vollzylinders mit einer ebenen Oberfläche an einem Ende beabstandet vom Isolator besitzt, und der aus Isolator an einem Bodenende der Zündkerze hervorsteht, wobei das Bodenende der Mittelelektrode vertikal um ungefähr 0,89 bis 1,22 mm von einer Massenelektrode (12) beabstandet ist, die an dem Metallgehäuse befestigt ist.
dadurch gekennzeichnet, daß

- die Massenelektrode (12) einen offen-ringförmigen Zündabschnitt (32, 34) besitzt, der an das Metallgehäuse (20) über wenigstens einen einstückigen Befestigungsausleger (38) befestigt ist, wobei der Abschnitt eine Lücke (46) von 0 - 2,5 mm besitzt,

- ein Oberteil des Zündabschnittes der Massenelektrode mit einer Distanz zur und parallel zu der ebenen Bodenfläche der Mittelelektrode (18) befestigt ist,

- ein innerer Ringdurchmesser der Massenelektrode konzentrisch um die Mittelelektrode verläuft,

- der Innendurchmesser der Massenelektrode ungefähr gleich mit dem Außendurchmesser der Mittelelektrode ist, und

- ein Zündmuster der Mittelelektrode ein ringförmiges Ringmuster um die Oberseite des Mittelelektrodenzündabschnittes bildet.

2. Eine Zündkerze nach Anspruch 1, dadurch gekennzeichnet, daß die Massenelektrode (12) und der Befestigungsarm (38) einstückig mit einem Befestigungsring (44) ist, der in einer Ebene parallel zu der Massenelektrode und vertikal beabstandet durch wenigstens einen Befestigungsausleger (38) verläuft.

3. Eine Zündkerze nach Anspruch 2, dadurchgekennzeichnet, daß das Metallgehäuse (20) eine Bolzenschürze (26) an seinem unteren Ende umgebördelt über den Befestigungsring (44) besitzt, um die Massenelektrode (12) über dem Befestigungsring zu positionieren.

4. Eine Zündkerze nach Anspruch 1, dadurch gekennzeichnet, daß der Isolator (16) ein keramisches Material ist.

5. Eine Zündkerze nach Anspruch 1, dadurch gekennzeichnet, daß der Innendurchmesser der Massenelektrode (12) 1 bis 1,1-mal so groß wie der Außendurchmesser der Mittelelektrode (18) ist.

6. Eine Zündkerze nach Anspruch 1, gekennzeichnet durch drei Befestigungsausleger (70), die an der Massenelektrode (12) befestigt sind.

Revendications

1. Bougie (10) pour moteur à combustion interne ayant une carcasse métallique (20) renfermant au moins partiellement un isolateur (16) contenant une électrode centrale conductrice (18) dont la partie inférieure (58) à la forme d'un cylindre plein à base plane, située à l'extrémité distale de l'isolateur et s'étendant de l'isolateur à l'extrémité basse de la bougie, l'extrémité inférieure de l'électrode centrale se trouvant espacée verticalement d'environ 0,89 à 1,22 mm d'une électrode de masse (12) attachée à la carcasse métallique (20),
caractérisée en ce que
   l'électrode de masse (12) se présente dans sa partie utile à l'allumage (32,34) sous la forme d'un anneau ouvert, laquelle partie est attachée à la carcasse métallique (20) par au moins un bras de fixation d'une seule pièce (38), ladite partie utile ayant un entrefer (36) de 0 - 2,5 mm,
   le sommet de la partie utile de l'électrode de masse est fixé à distance de l'électrode centrale (18) et parallèlement à la surface plane inférieure de ladite électrode centrale (18),
   la circonférence interne en anneau de l'électrode de masse est concentrique avec l'électrode centrale,
   le diamètre interne de l'électrode de masse est égal au diamètre extérieur de l'électrode centrale et
   le réseau d'allumage partant de l'électrode centrale forme un réseau en anneau autour du sommet de la partie utile de l'électrode de masse.

2. Bougie selon revendication 1 caractérisée en ce que l'électrode de masse (12) et le bras de fixation (38) forment une seule pièce avec une bague de fixation (44) qui est disposée dans un plan parallèle à l'électrode de masse et qui est verticalement espacée par au moins un bras de fixation (38).

3. Bougie selon revendication 2 caractérisée en ce que la carcasse métallique (20) possède à son extrémité inférieure un embout chemisé (26) serti au-dessus de la bague de fixation (44) pour le positionnement de l'électrode de masse (12) au-dessus de cette bague.

4. Bougie selon revendication 1 caractérisée en ce que l'isolateur (16) est en céramique.

5. Bougie selon revendication 1 caractérisée en ce que le diamètre interne de l'électrode de masse (12) est de 1 à 1,1 fois le diamètre externe de l'électrode centrale (18).

6. Bougie selon revendication 1 caractérisée par trois bras de fixation (70) attachés à l'électrode de masse (12).

Drawing