WO2006014840A2 - Multi-spark spark plug - Google Patents

Abstract

A spark plug (Figure 1) includes an insulative body (40), a main electrode (20), a ground (26); and at least one intermediate electrode (22A, 22B, 24A, 24B) in series with the main electrode, each having first and second ends and a mid portion in between the ends, wherein the intermediate electrode is partially embedded within the insulative body, such that the first and second ends of the electrode extend from the combustion chamber facing surface of the insulative body and the mid portions embedded in the insulative body such that a gap is formed between the main electrode and the first end of the first of the at least one intermediate electrodes and a final gap is formed between a second end of the final one of the at least one intermediate electrodes and the ground electrode. Fletcher discloses the electrodes placed in a ring-like manner around the outer edge of the insulative body.

Description

MULTI-SPARK SPARK PLUG

CROSS-REFERENCE TQ RELATED APPLICATION

[0001] The present application claims priority under 35 U. S. C. §119(e) to

U.S. Provisional Patent Application No. 60/591,645, filed July 28, 2004.

BACKGROUND OF THE INVENTION Field of Invention

[0002] This invention relates to a sparkplug for an internal combustion engine, and more particularly, to a sparkplug with multi-sparking electrodes.

Description of Related Art

[0003] Typically, sparkplugs utilize a single centrally located positive electrode that discharges the high voltage to a ground electrode. Certain plugs may contain two, three or four ground electrodes evenly spaced away from the center positive electrode. The centrally located positive electrode will often only have enough energy to jump the gap to one of the ground electrode (i.e., the path to the least resistance). In the event of crowding up the positive electrode, sparks may contact the second, or third and forth ground electrode. However, the spark source is still located at the center of the plug. The combustion generated from such a plug has to radially travel to the perimeter of the cylinder and expand axially in the piston direction.

[0004] What is desired is a spark plug that consistently and reliably forms multiple sparks with each firing sequence of the spark plug. It is also desired that the spark plug be manufacturable in a cost effective manner.

SUMMARY OF THE INVENTION

[0005] The invention pertains to a spark plug that substantially simultaneously produces a plurality of sparks in a combustion chamber of an internal combustion engine. The spark plug includes an insulative plug body having and a combustion chamber facing surface. The spark plug also includes a main electrode, a ground, and at least one intermediate electrode in series with the main electrode and said ground. The intermediate electrode(s) each have first and second ends and a mid portion in between the ends. Each intermediate electrode is partially embedded within the insulative body such that the first and second ends of the electrode extend from the combustion chamber facing surface of the insulative body and said mid portion is embedded in the insulative body. A first gap is formed between the main electrode and the first end of the first of the at least one intermediate electrodes and a final gap is formed between a second end of the final one of the at least one intermediate electrodes and the ground electrode so that high voltage power jumps across the plurality of gaps to form a plurality of sparks. In one embodiment, the intermediate electrodes are generally U-shaped electrodes.

[0006] The invention also pertains to a method for manufacturing a spark plug that substantially simultaneously produces a plurality of sparks in a combustion chamber of an internal combustion engine. The method includes forming an insulative plug body having a combustion chamber facing surface. The method also includes inserting a main electrode through the insulative body and affixing a ground to the insulative body. The method further includes inserting at least one intermediate electrode into the insulative body in series with the main electrode and said ground. Each intermediate electrode has first and second ends and a mid portion in between said ends. The intermediate electrodes are inserted such that they are partially embedded within the insulative body such that the first and second ends of said electrode extend from the combustion chamber facing surface of the insulative body and said mid portion is embedded in the insulative body such that a first gap is formed between the main electrode and the first end of the first of the at least one intermediate electrodes and a final gap is formed between a second end of the final one of the at least one intermediate electrodes and the ground electrode so that high voltage power jumps across the plurality of gaps to form a plurality of sparks. [0007] These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above mentioned and other features of this invention will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0009] Figure 1 illustrates a spark plug according to one aspect of the invention; [0010] Figure 2 illustrates partially cut away view of the spark plug of Figure

1;

[0011] Figure 3 illustrates the electrodes being inserted in the spark plug of

Figure 1; and

[0012] Figure 4 illustrates partially cut away view of the spark plug of Figure

1.

[0013] Corresponding reference characters indicate corresponding parts throughout the views of the drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS [0014] The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description.

[0015] Referring now to Figures, the present invention builds on the extremely reliable technology of the spark plugs used in internal combustion engines. Figure 1 shows a combustion chamber end of a spark plug 10 having an insulative body 40. As is known in the art, the spark plug 10 desirably includes a conductive outer housing (not shown) that is provided with a screw thread (not shown) and a hexagon drive (now shown). The spark plug 10 is screwed into a mating thread in the cylinder head of an internal combustion engine so that spark plug 10 projects into a combustion chamber of a cylinder of the internal combustion engine. As is typical with most common spark plugs, the spark plug 10 may be connected with the support structure of an internal combustion engine (not shown). Further, as is typical with most common spark plugs, the spark plug 10 may be provided with an engagement portion (not shown) for facilitating engagement of the spark plug 10 with a tool such as a wrench for threadily engaging the spark plug 10 with the cylinder head. Except as set forth herein, details which are known in the art, such as those associated with the fabrication of a spark plug, are not provided in order not to unnecessarily obscure the present invention.

[0016] According to the invention, the spark plug 10 utilizes a plurality of electrodes positioned in series with spark-forming gaps formed between adjacent electrodes. As best seen in conjunction with the cutaway view of the spark plug 10 depicted in FIG. 2, the spark plug 10 includes a first main electrode 20, two intermediate electrodes 22, 24 and a final ground 26. The ground 26 may comprise or be connected to the conductive outer shell of the spark plug 10. In this respect the insulative body 40 electrically insulates the electrode 20, 22, 24 from having direct electrical contact with the conductive outer housing. However, more or fewer intermediate electrodes may be included using sound engineering judgment depending on the desired number of sparks to be produced without departing from the scope of the invention.

[0017] A first gap 30 is formed between the main electrode 20 and a first end

22A of the first intermediate electrode 22. A second gap 32 is formed between a second end 22B of the first intermediate electrode 22 and a first end 24A of the second intermediate electrode 24. A third gap 34 is formed between a second end 24B of the second intermediate electrode 24 and the ground electrode 26. Thus, the high voltage power jumps a plurality of gaps 30, 32 through the series of electrodes 20, 22, 24 before jumping to ground at the final gap 34, substantially simultaneously forming separate sparks at each gap. It is contemplated that such a series of sparks may quickly merge to form large stable flame front for ignition. [0018] The number of electrodes and the placement of the electrodes and thus the spark producing gaps are selected based on the size of the cylinder in which the spark plug is to be received or the available area in the combustion chamber (i.e., typically the middle of the radius of the cylinder). In the illustrated embodiment, the electrodes are placed in a ring-like manner around the outer edge of the insulative body 40. However, one skilled in the art will understand that the electrodes may be placed in other orientations. The materials used to make the electrodes 20-26 and the insulative body portion 40 of the spark plug 10 can be materials commonly used for such applications in known spark plugs.

[0019] Desirably, the spark plug 10 is manufactured by embedding the main electrode 20 and the intermediate electrodes 22, 24 in the insulative end portion 40 of the spark plug 10. The main electrode 20 includes an electrical connection end 2OA and a spark ignition end 2OB. Preferably, the main electrode 20 extends through the insulative body 40 with the spark ignition end 20B and the electrical connection end 2OA protruding beyond the insulative body 40 in opposing directions along the longitudinal axis of the spark plug 10. The electrical connection end 2OA facilitates connection to a source of electrical current (not shown). The intermediate electrodes 22, 24 are generally U-shaped electrodes and are sealed in the insulative portion 40 of the spark plug body such that the ends 22A, 22B, 24A, 24B of the electrodes 22, 24 extend from a combustion chamber facing surface 42 of the spark plug body 10 as shown in FIG. 1. As best seen in FIG. 2, the intermediate electrodes 22, 24 have a mid portion 23 connecting the respective ends 22A, 22B, 24A, 24B that is embedded in the insulative body portion 40 of the spark plug. The ends 22 A, 22B, 24A, 24B of the intermediate electrodes 22, 24 are spaced apart from one another to form the spark gaps 30, 32, 34 between adjacent ends. Using this design, a spark plug 10 having multiple electrodes 20, 22, 24, 26 can be manufactured in an economical manner. [0020] As illustrated in FIGS. 3 and 4, the spark plug may be manufactured by inserting the electrodes 20, 22, 24, 26 in the insulative body portion 40 of the spark plug body 10 and then sealing the insulative body portion using methods well known in the art. The insulative body 40 may be a ceramic molding. In one embodiment, the electrodes 20, 22, 24, 26 can be positioned then the insulative body 40 is molded around the electrodes using conventional techniques.

[0021] In practice, the spark plug 10 facilitates the formation of an electrical circuit. In this respect, electrical current may be applied to the electrical connection end 2OA of the main electrode 20 and may flow to the spark ignition end 2OB thereof. Such current may continue to flow progressively to the intermediate electrodes 22, 24 by traversing the spark gaps 30, 32 therebetween in the form of sparks. The electrical circuit is completed as a spark traverse from the last intermediate electrode 24 to the ground 26. As one of ordinary skill in the art will appreciate, the size, shape, material selection and relative positioning of the spark ignition end 2OB of the main electrode 20, the intermediate electrodes 22, 24 and the ground 26 will impact upon the propensity of sparks traversing the spark gaps 30, 32, 34.

[0022] While this invention has been described in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of this invention, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this invention. [0023] What is claimed is:

Claims

1. A spark plug for substantially simultaneously producing a plurality of sparks in a combustion chamber of an internal combustion engine, the spark plug comprising:

an insulative plug body having an a combustion chamber facing surface; a main electrode; a ground; and at least one intermediate electrode in series with the main electrode and said ground, said intermediate electrode(s) each having first and second ends and a mid portion in between said ends, wherein the intermediate electrode(s) is partially embedded within the insulative body such that the first and second ends of said electrode extend from the combustion chamber facing surface of the insulative body and said mid portion is embedded in the insulative body such that a first gap is formed between the main electrode and the first end of the first of the at least one intermediate electrodes and a final gap is formed between a second end of the final one of the at least one intermediate electrodes and the ground electrode so that high voltage power jumps across the plurality of gaps to form a plurality of sparks.

2. The spark plug according to claim 1 wherein there are two intermediate electrodes, wherein a gap is formed between the second end of the first intermediate electrode and the first end of the second intermediate electrode so that high voltage power jumps across said gap to form one of the plurality of sparks.

3. The spark plug according to claim 2 wherein the electrodes are placed in a ring-like manner around the outer edge of the insulative body.

4. The spark plug according to claim 1 the intermediate electrodes are generally U-shaped electrodes.

5. A method for manufacturing a spark plug that substantially simultaneously produces a plurality of sparks in a combustion chamber of an internal combustion engine, the method comprising: forming an insulative plug body having an a combustion chamber facing surface; inserting a main electrode through the insulative body; affixing a ground to the insulative body; and inserting at least one intermediate electrode into the insulative body in series with the main electrode and said ground, said intermediate electrode(s) each having first and second ends and a mid portion in between said ends, wherein the intermediate electrode(s) are inserted such that they are partially embedded within the insulative body such that the first and second ends of said electrode extend from the combustion chamber facing surface of the insulative body and said mid portion is embedded in the insulative body such that a first gap is formed between the main electrode and the first end of the first of the at least one intermediate electrodes and a final gap is formed between a second end of the final one of the at least one intermediate electrodes and the ground electrode so that high voltage power jumps across the plurality of gaps to form a plurality of sparks.

6. The method for manufacturing a spark plug according to claim 5 further including sealing the insulative body after inserting the at least one intermediate electrode.