TECHNICAL FIELD:

The present invention relates to a spark plug for the internal combustion engine, and more particularly relates to a high efficiency spark plug.

BACKGROUND ART:

Internal combustion engines employ spark plugs for igniting the air and fuel mixture in the engine cylinder combustion chamber for providing the power to rotate the crank shaft. Heretofore, spark plugs are provided with electrodes located outside the bottom end of the spark plug body to extend into the engine combustion chamber. In operation, the electrodes are exposed to the extremely high heat produced in the combustion chamber, which causes physical erosion of the electrodes. Also, burned particles such as carbon are deposited on the electrodes to result in the loss of effectiveness of the ignition function of the spark plug. Approximately, 80% of the air and fuel mixture is bumed in each cycle of the ignition of a conventional spark plug. A large amount of waste materials including noxious gases such as carbon monoxide, carbon dioxide, nitrogen oxides and hydrocarbon and other partially burned or unburaed materials are produced in the engine chamber in the ignition. Some of the materials and noxious gases are discharged from the engine to the atmosphere, which cause pollution of the latter. The pollution may be reduced by passing the discharge through a catalytic converter. However, the remaining waste materials in the ignition chamber will mix with the fresh air and fuel mixture subsequently injected into the ignition chamber to form a contaminated and degraded fuel mixture which inherent causes the reduction of the ignition efficiency and the loss of power output from the engine with high consumption of fuel. Furthermore, with the electrodes of the spark plug located in the combustion chamber, ignition would occurs in the combustion chamber of the engine so that the component parts in the combustion chamber are subjected directly to the high temperature of the combustion. The high temperature reduces the life of the engine due to heat stress of the components.

Attempts have been made to provide new spark plug constructions with the electrodes located within a hollow pre-ignition chamber formed in the spark plug body or shell surrounding the electrodes in a spaced manner. The central electrode and the grounding electrode are recessed and spaced from the lower opening of the pre-ignition chamber. The grounding electrode may also separate the pre-ignition chamber into a lower chamber between the central electrode and the lower opening of the shell and an upper chamber surrounding the insulated portion of the central electrode. Ignition occurs in the lower chamber so that the flame is injected into the cylinder chamber to ignite the air and fuel mixture therein resulting in less waste materials produced in the ignition and less high temperature exposure to the engine components. However, waste materials still produced in the pre-ignition chamber. The waste materials, again as in the conventional spark plug, would mix with the fresh air and fuel mixture injected into the cylinder chamber to form a concentrated polluted mixture in the pre-ignition chamber to cause unsatisfactory ignition and back fire.

SUMMARY OF THE PRESENT INVENTION

It is a principal object of the present invention to provide an improved spark plug which operates with negligible amount of pollutant produced in the ignition and in the combustion engine exhaust discharge.

It is another object of the present invention to provide an improved spark plug which is operative with high ignition efficiency and low fuel consumption.

It is another object of the present invention to provide an improved spark plug construction having three chambers including a lower chamber located below the grounding electrode and the central electrode, a middle chamber surrounding the insulated lower portion of the central electrode and an upper chamber surrounding the upper insulated portion of the insulator to maintain it in an optimum operating temperature..

It is yet another object of the present invention to provide an improved spark plug construction to provide maximum power output of the ignition of the air and fuel mixture injected into the cylinder chamber of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments thereof in connection with accompanying drawings in which

Figure 1 is a partial cross sectional perspective side elevation view of the spark plug of the present invention.

Figure 2 is an enlarged bottom cross sectional elevation view along the cross section line II-II of Figure 1. Figure 3 is an enlarged bottom cross sectional elevation view along the cross section line II-II of Figure 1 showing communication openings of various shapes formed in the annular ring.

Figure 4 is an enlarged bottom cross sectional elevation view along the cross section line IV-IV of Figure 1.

Figure 5 is an enlarged bottom cross sectional elevation view along the cross section line IV-IV of Figure 1 showing an alternative multi-angular opening formed in the grounding electrode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings wherein like reference numerals in the various views designate corresponding parts, the spark plug 10 of the present invention has a generally cylindrical metal body or shell 11 similar to a conventional spark plug. Threads are provides on the outer surface of the lower portion of the shell 11 for mounting the spark plug 10 to an internal combustion engine. The central electrode 12 is made of a high temperature resistant noble metal or metal alloy and it is surrounded and imbedded in a ceramic insulator 13 which has an upper portion 13 extending upwards from the top of the shell 11, and an electrical connection terminal 14 is located at the top of the central electrode for conducting the ignition current to the spark plug. The lower portion of the ceramic insulator 13 has a generally frusto-conical lower end portion 15 extending downwardly into a hollow cylindrical cavity 16 located within the lower end portion 17 of the shell 11. Threads are provided on the outer surface of the lower end portion of the shell 11 for mounting the spark plug to the cylinder head of an internal combustion engine.

An annular partition ring 18 is located in a generally horizontal position within the cylindrical cavity 16 and is spaced from the upper end of the latter. The annular partition ring

18 is made of a high temperature resistant noble metal or metal alloy and it has an outer diameter equal to the inner diameter of the cylindrical cavity 16 and a central inner opening

19 having a diameter equal to the outer diameter of a predetermined position of the frusto- conical lower end portion 15 of the ceramic insulator 13 such that when the annular partition ring 18 is inserted into the cylindrical cavity 16 it is retained in the predetermined position horizontally such that an upper chamber 20 is formed at the upper portion of the cylindrical cavity 16 with the inner opening 19 of the annular partition ring 18 intimately engaged with the conical side wall of the lower end portion of the ceramic insulator 13. A plurality of through openings 21 are formed in the annular partition ring 18 as shown in Figures 2 and 3. The through openings 12 may have various shapes including circular, rectangular, or multi- angular shapes as best shown in Figure 3. The through openings 12 may be all of the same shape or a mixture of the various different shapes.

A cylindrical sleeve 22 also made of a high temperature noble metal or metal alloy is located within the lower portion of the cylindrical cavity 12 below and abutting the annular partition ring 18. The cylindrical sleeve 22 has an outer diameter equal to the inner diameter of the cylindrical cavity 12 such that it is snugly mounted within the latter. The cylindrical sleeve 22 has an annular shoulder member 23 having an inner opening 24 with a flange extending inwardly and horizontally at a predetermined location from the inner side wall of the cylindrical sleeve 22. The annular shoulder member 23 forms the grounding electrode of the spark plug with the edge of the inner opening 24 located directly spaced from the spark tip 25 of the central electrode 12. The shoulder member 23 separates the inner cavity of the cylindrical sleeve 22 into a middle chamber 26 and a lower outer chamber 27 as shown in Figure 1. The middle chamber 26 is located above the grounding electrode and the lower chamber is located below the grounding electrode. The middle chamber 26 communicate with the upper chamber 20 through the through openings 12 in the annular partition ring 18. The spacing between the edge of the inner opening 24 of the grounding electrode and the spark tip 25 of the central electrode 12 provides the spark gap of the spark plug. The center of the inner opening 24 is preferably offset from the vertical longitudinal axis of the central electrode 12 such that the tip 25 is positioned closer to one side edge of the inner opening 24 as best shown in Figures 1, 4 and 5 in order to achieve a more intense spark in operation. The inner opening 24 of the grounding electrode may have various shapes including circular or multi-angular shape as shown in Figures 4 and 5..

The locations of the annular partition ring 18 in the cavity 16 and the grounding electrode 23 in the cylindrical sleeve 22 are determined by the compression ratio of the air and fuel mixture in the combustion chamber of the internal combustion engine in which the spark plug is to be installed, as shown in the following formula: v, + v ₂

V ₃ = mm ³

e in which V, is the volume of the lower chamber 27

V ₂ is the volume of the middle chamber 26

V ₃ is the volume of the upper chamber 20, and

e is the compression ratio of the air/fuel mixture in the combustion chamber The rim 28 of the bottom opening of the lower chamber 27 is preferably slanting inwardly and downwardly as shown in Figure 2 to provide a reduced bottom opening which guides and accelerates the ignition flame from the lower chamber 27 into the combustion chamber of the engine.

In operation, initially the air and fuel mixture is injected into the combustion chamber of the combustion engine as well as the lower chamber of the spark plug. The mixture in the lower chamber 27 is ignited by the spark between the central electrode and the ground electrode occurring at the spark gap of the spark plug. Any high temperature unbumed materials and/or noxious gases produced in the ignition is mainly confined within the lower chamber of the spark plug. The ignition will cause the air and fuel mixture in the combustion chamber to ignite instantaneously. Subsequent fresh air and fuel mixture injected into the combustion chamber of the engine will force the high temperature waste materials and/or noxious gas, if any, in the lower chamber27 to rise mainly into the middle chamber and then through the openings 21 of the partition annular ring 18 into the upper chamber of the spark plug. Thus, the components in the combustion chamber of the engine are not subjected to the high temperature of the combustion; and the temperature in the combustion chamber only rises for the short period in the ignition and they are, in fact, cooled by the incoming fresh air and fuel mixture. Thus, it reduces the temperature stress to the engine components. The high temperature waste materials and/or any obnoxious gases are confined within the upper chamber and middle chamber so that they maintain the spark plug at an optimum operating temperature. In this manner, the high temperature is utilized to maintain the optimum temperature of the spark plug to result in a high efficiency in ignition and power output with less fuel consumption and longer engine life.

Since the partition annular ring 18, the cylindrical sleeve 22 and the central electrode 25 and the grounding electrode 23 are all made of high temperature noble metal or metal alloy, they are not subject to high temperature erosion. Also, cleaning and re-setting of the spark gap are not required.

Only a small amount of the waste materials in the middle chamber and the upper chamber of the spark plug is drawn back into the lower chamber in the subsequent repeated combustion operations and it is being burned and eliminated in the further combustion such that discharge of unburned waste materials from the engine is minimal. Therefore, discharge of pollution to the atmosphere of unburned waste materials from the engine using the present spark plug is negligible.