SPARK PLUG WITH A RING/OPEN-RING SHAPED GROUND ELECTRODE

Abstract: Spark plug for an internal combustion engine having a metal shell (20) enclosing a ceramic insulator (16) containing a conductive centre electrode (18) having a bottom end (58) exiting from the insulator. The bottom end of the centre electrode is spaced apart from a ground electrode (12) attached to the metal shell by at least one support member or mounting post (38). The ground electrode is ring/open-ring shaped and its interior diameter ranges from equal to the exterior diameter of the centre electrode to a multiple of the size of the interior diameter of the centre electrode.

Description: SPARK PLUG WITH A RING/OPEN-RING SHAPED 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 of the centre electrode being spaced apart from 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 achieving 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 2,4-87 ,535 describes an annular tapered curved fork 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 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. 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. 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. According to the invention the spark plug is characterized in that it comprises a ring/open-ring shaped ground electrode with a small gap on the open ring which is diametrically opposite to one support member, said ring/open-ring shaped ground electrode being coaxial to centre electrode, and its interior diameter ranging from equal to the exterior diameter of the centre electrode, to a multiple of the size of the interior diameter of the centre electrode. Preferably 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 ring/open-ring shaped ground electrode. The ring/open-ring shaped ground electrode is attached to the metal shell by at least three spaced support members. According to another embodiment of the invention, the ring/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 ring/open-ring shaped ground electrode. 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 . According to an advantageous embodiment of the invention, the ring /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 ring/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. It has been established that an uniform diameter ring/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 ring/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 that 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 : 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 isometric view of the ground electrode component of Fig. 6 welded in place. Fig . 8 is 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. 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 . Spark plug 10 shown in Fig . 1 is a conventional internal combustion engine spark plug except for the ring/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. 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 .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 4-0 to the back end of the rin /open-ring shaped ground electrode 12 and at a second end 4-2 to a mounting ring LL. 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 from a high quality metal such as a nickel/chromium alloy, platinum alloy and the like. The sharp right angle 4-8 of mounting post 38 is important to enhance the spark qualities to be discussed hereafter. 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 .04-5 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. 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. 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 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 %. By casting the electrode 12, greater variability in the metal usage can be achieved to obtain the optimum longevity of the electrode 12. Alternatively, the electrode 12 can be stamped out or ground out from a piece of metal. 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. The spark plug of Figs 9 and 10 comprises a ground electrode component 46 consisting of the ring/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. 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 plan parallel to the plan of the ring/open-ring shaped ground electrode . 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: Claims 1. Spark plug for an internal combustion engine having a metal shell at least partially enclosing an insulator containing a conductive centre electrode, the centre electrode having a bottom end exiting from the insulator at a bottom end of the 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, characterized in that it comprises a ring/open-ring shaped ground electrode with a small gap on the open ring which is diametrically opposite to one support member, said ring/open-ring shaped ground electrode being coaxial to centre electrode, and its interior diameter ranging from equal to the exterior diameter of the centre electrode, to a multiple of the size of the interior diameter of the centre electrode 2. Spark plug according to claim 1, characterized in that the gap has two parallel edges. 3. Spark plug according to claim 1 , characterized in that the gap has two radial edges. 4. Spark plug according to claim 1 , characterized in that the distance of the edges of the gap range from 0 to 2,5 mm. 5. Spark plug according to claim 1 , characterized in that the at least one support member is a reversed L-shaped supporting bracket. 6. Spark plug according to claim 5, characterized in that one leg of the reversed L-shaped supporting bracket is located in the plane of the ring/open-ring shaped ground electrode. 7. Spark plug according to claim 1 , characterized in that the ring/open-ring shaped ground electrode is attached to the metal shell by at least three spaced support members. 8. Spark plug according to claim 1 , characterized in that the ring /open-ring shaped ground electrode is 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 ring /open-ring shaped ground electrode. 9. Spark plug according to claim 1 , characterized in that the metal shell lower end is a shank skirt crimped over the mounting ring to hold the ground electrode in position or by welding . 10. Spark plug according to claim 1 , characterized in that the ring/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 . 11. Spark plug according to claim 10, characterized in that a back end of the ring /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. 12. Spark plug according to claim 8, characterized in that 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. 13. Spark plug according to claim 9, characterized in that the gap is diametrically opposite to at least one support element.

Inventors: JOHNSON JAMES E, JOHNSON, JAMES, E.
Applicants: NITHARDT ROLAND, ULTRA PERFORMANCE INTERNATIONA, NITHARDT, ROLAND, ULTRA PERFORMANCE INTERNATIONAL
Application year: 1990
Main classification: H01T13
IPC codes: H01T13