WO2009004648A2

WO2009004648A2 - Spark plug for internal combustion engine

Info

Publication number: WO2009004648A2
Application number: PCT/IN2008/000314
Authority: WO
Inventors: Ramanlal Gobarbhai Tirkar
Original assignee: Ramanlal Gobarbhai Tirkar
Priority date: 2007-05-24
Filing date: 2008-05-16
Publication date: 2009-01-08
Also published as: WO2009004648A3

Abstract

The present invention relates to spark plug for an internal combustion engine that comprises of center electrode, plug shell, ground electrode, height adjusting bolt, insulator, outer jacket, gasket, terminal nut, washer and lock nut. All these parts can be separated from each other due to which cleaning and maintenance of the spark plug becomes easy. The ground electrode proposed by this invention is 'C' shaped. Due to 'C' shape, larger sparking area is available between the ground electrode and center electrode. It ensures the occurrence of the proper sparking. It also causes complete combustion of air-fuel mixture and thereby improves the engine efficiency. Another novel feature of the present invention is adjustable center electrode. The height of the center electrode can be adjusted by the height adjusting bolt. Because of height adjusting feature, the spark gap is easy to maintain and spark plug can be used for longer period

Description

SPARK PLUG FOR INTERNAL COMBUSTION ENGINE

FIELD OF THE INVENTION

The present invention relates to a spark plug for the internal combustion engine. More specifically it relates to a spark plug having adjustable center electrode for longer life of the spark plug.

It also relates to a spark plug in which all parts of the spark plug can be separated from each other which ensures the proper cleaning and maintenance of the spark plug.

BACKGROUND OF THE INVENTION

The spark plug is an electrical device threaded into the cylinder of an internal combustion engine to ignite the fuel mixture by producing timed sparks between electrodes.

The sparks plugs mounted in the engine's combustion chamber play a critical role by igniting the fuel-air mix. Gasoline engines obtain power by compressing a fuel-air mixture of air and gasoline, then exploding this mixture by ignition. Spark plugs serve to ignite this fuel-air mixture. With the battery as the power source, the spark plug converts the electrical energy that comes through the ignition coil and distribute into a spark, which ignites the fuel air mixture. In other words, without the spark plug, the engine doesn't run. The spark plug is an important part because its performance influences the overall performance of the engine.

When the high voltage produced by the ignition system is applied between the center electrode and ground electrode of the spark plug, the insulation between the electrodes breaks down, current flows in the discharge phenomenon, and an electrical spark is generated.

This spark energy triggers ignition and combustion in the compressed air-fuel mixture. This discharge is of extremely brief duration (about 1/1000 of a second) and is extraordinarily complex.

There are various patents available for spark plugs. Some of them have been discussed herein after.

A Japanese patent JP2044674 discloses a front end side insulator, made of very heat-conductive ceramics and on whose rear end an annular groove with L-shaped cross-section is formed, is fitted into a mold for a rear end side insulator, and the rear end side insulator is injection molded after an annular projection with L-shaped cross- section is formed by injecting a heat resisting resin material. Thus, the front end side insulator and the rear end side insulator are strongly fitted together by means of the annular groove and the annular projection formed on them respectively to be joined, so that the dislocation of the joined portion is prevented from occurring, and further, the backlash between the front end side insulator and the rear end side insulator to loose the air tightness and to lead to breaking can be prevented from occurring. The purpose of this invention is to improve durability of the joined portion between the rear part of a front-end side insulator and a rear end side insulator by using very heat- conductive ceramics for the front-end side insulator and a heat resisting resin material easy to effect joining process for the rear end side insulator.

The United States patent US6073607 discloses a spark plug includes an insulator body provided with a longitudinally extending through bore. A one-piece, central electrode is secured within the longitudinally extending through bore, while simultaneously providing an annular zone communicating with a combustion chamber. An earth lower electrode projects diametrically inward towards the central electrode and is spaced a longitudinally fixed distance beyond the lower end of the central electrode. A first, non- central longitudinally extending bore in the insulator body is connected to a fuel-metering device for controllably admitting fuel to the combustion chamber. A second, non-central, longitudinally extending bore in the insulator body is connected between the combustion chamber and an exhaust manifold to exhaust gases from the combustion chamber. A lower-threaded base connects the spark plug to an opening in the combustion chamber.

The patent document WO2007134296 discloses a composite ignition device includes a positive electrode having a tip formed thereon that is bonded to a first insulator to form a firing cone assembly. A second insulator having a negative capacitive element embedded therein is attached to the firing cone assembly. A positive capacitive element is disposed in the second insulator and is separated from the negative capacitive element by the second insulator. The positive capacitive element is coupled to the positive electrode. The positive and negative capacitive elements form a capacitor. A resistor is coupled to the positive capacitive element. An electrical connector is coupled to the resistor and attached to the second insulator. A shell including a negative electrode having a tip is attached to the second insulator and the firing core assembly and coupled to the negative capacitive element. The negative electrode tip is spaced apart from the positive electrode tip. The above discussed spark plugs and other spark plugs, which are available in the market, are single piece in the construction. One piece in construction means all the parts of the spark plug are permanently fitted to each other and cannot be separated from each other. Since the individual components of such spark plugs cannot be separated from each other, cleaning and maintenance of such spark plug becomes very difficult and cumbersome.

Further the central electrode is always permanently fixed in the spark plug. Due to continuous use, the center electrode is subjected to wear and tear at its top. This wear and tear of center electrode widens the spark plug gap i.e. gap between center electrode and ground electrode. This widening of the spark plug gap results into improper generation of the electric spark and thereby causes incomplete ignition of fuel-air mix. Hence it is always essential to adjust the spark plug gap for proper functioning of the spark plug and engine. Generally the spark plug gap is adjusted by bending the ground electrode towards the center electrode. This is because the center electrode is permanently fixed and hence not adjustable. It causes the frequent replacement of the spark plug.

Also in the above-discussed spark plugs, the ground electrode is rectangular "L" shaped. This rectangular "L" shaped ground electrode spark plugs are always susceptible to problems like frequent misfiring and weak flame. The misfiring is the failure of the fuel air mixture on one or more cylinders to undergo combustion while vehicle is in running mode. This engine condition can be caused by worn, dirty or incorrectly gapped spark plugs. The misfire of spark plug causes the wastage of fuel.

In short the above-discussed spark plugs suffer from the following disadvantages:

i. Cleaning and maintenance of such spark plug is very difficult and cumbersome. ii. Working life of spark plug is very less. iii. They are susceptible to problems like frequent misfiring and weak flame. iv. Such spark plugs causes increase in the fuel consumption and emissions. v. Due to use of such spark plugs, the efficiency of engine reduces. Hence there is a need of new kind of spark plug which will address all afore mentioned disadvantages bf the prior art spark plugs and operate efficiently to improve engine efficiency.

OBJECTS OF THE INVENTION

The main object of the present invention is to provide a spark plug which overcome the deficiencies of the prior art spark plugs.

Another object of the present invention is to provide a spark plug in which components of the spark plug can be separable from each other to ensure proper cleaning and maintenance of the spark plug.

Yet another object of the present invention is to provide a spark plug in which center electrode is adjustable to maintain the proper spark plug gap with ground electrode.

Yet another object of the present invention is to provide a spark plug having longer working life.

Yet another object of the present invention is to provide a spark plug, which provides the reliability. Still another object of the present invention is to provide a spark plug, which reliably generates a strong spark between electrodes accurately at specified time to create the trigger for combustion of the gas mixture.

Yet another object of the present invention is to provide a spark plug, which operates efficiently and ensures the maximum efficiency of the engine.

Yet another object of the present invention is to provide a spark plug, which avoids the wastage of fuel occurring due to misfiring.

Yet another object of the present invention is to provide a spark plug, which is lightweight and easy to use.

SUMMARY OF THE INVENTION

Accordingly to achieve the aforesaid objects present invention provides a spark plug for an internal combustion engine comprises:

a plug shell for installing the spark plug into cylinder head of the internal combustion engine, said plug shell is hollow and consists of plug fitting threaded structure and plug fitting nut, said plug shell having threads over inner surface;

a ground electrode having "C" shape and being joined to the upper edge of the plug fitting threaded structure of said plug shell;

center electrode having an elongated rod like structure being lies lengthwise within the plug and conducts electricity from the ignition cable hooked to one end of the plug to the electrode gap at other end, said center electrode comprises circular head at top, ridged surface at bottom and plane surface in between said head and ridged surface, said head having diameter greater than diameter of the remaining portion of said center electrode;

height adjusting bolt being removably fitted inside the plug shell to adjust the height of said center electrode as per the need, said bolt having upper portion and bottom portion, said upper portion having plane outer surface and said bottom portion having threads over the outer surface, wherein bottom portion of said height adjusting bolt get fitted inside the threads of the inner surface of the plug shell, said bolt comprises threads over inner surface along whole length of the bolt; outer ceramic jacket to cover the plane surface of the center electrode and being removably fitted into the height adjusting bolt, said outer jacket is elongated, tapered at one end and having longitudinally extending bore at the center, said outer jacket having threads over outer surface except in the tapered region, wherein said threads of the outer jacket fitted into the inner threads of the height adjusting bolt;

insulator made of plastic material to insulate center electrode from said plug shell and height adjusting bolt, said insulator surrounds the center electrode, said insulator comprises threads over outer surface and longitudinally extending through bore at the center, said insulator having depression at one end to tightly accommodate the non tapered end of the outer jacket, wherein said insulator is removably fitted in height adjusting bolt through threads; and

terminal nut being connected to ridged surface of center electrode and ignition cable of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 : Shows the perspective view of the spark plug in accordance to the present invention. Figure 2 : Shows another view of the spark plug in accordance to the present invention. Figure 3 : Shows the cross sectional view of the spark plug in accordance to the present invention. Figure 4 : Shows the detailed view of the spark plug of the present invention with all parts separated from each other.

Figure 5 : Shows the top, front, side and cross sectional views (a) - respectively of the plug shell being used in the spark 5(d) plug of the present invention.

Figure 6 : Shows the perspective view of the height adjusting bolt of the spark plug of the present invention. Figure 7 : Shows the perspective view of the center electrode of the spark plug of the present invention. Figure 8 : Shows the perspective view of the outer jacket of the spark plug of the present invention. Figure 9 : Shows the perspective view of the insulator of the spark plug of the present invention.

^{^} DETAILED DESCRIPTION OF THE INVENTION

The above, and the other objects, features & advantages of invention will become apparent from following description read in conjunction with the accompanying drawings.

Referring to figures 1 to 4, the spark plug (1) of the present invention comprises center electrode (2), plug shell (3), ground electrode (4), height adjusting bolt (5), insulator (6), outer jacket

(7), gasket (8), terminal nut (12), washer (9) and lock nut (10). All these parts can be separated from each other due to which cleaning and maintenance of the spark plug (1) becomes easy.

As shown in figures 1-4 and 5(a)-5(d), the Plug shell (3) is a hollow rod like structure which installs the spark plug (1) into the cylinder head of the internal combustion engine. It consists of two parts one

(31) is having plug fixing threads over it and other is the plug fitting nut (32). The first part (31) is having circular rod like structure. The threads are provided over its outer surface. The spark plug (1) gets fitted into the engine via this threaded structure. The second part

(32) is plug-fixing nut having hexagonal head. Threads are provided on the inner surface of the plug-fixing nut (32).

The plug shell (3) is a single piece in construction where first and second parts (31, 32) are permanently fixed to each other.

Diameter of the first part (31) is less than the diameter of the second part (32). The plug shell (3) surrounds the center electrode

(2) and outer jacket (7). Plug shell removes the heat from spark plug ( 1) to the cylinder head of the engine. The plug shell (3) is generally made of steel material. The gasket (8) makes the plug shell (3) and internal combustion engine fit tightly to each other. It also maintains the air tightness of the combustion chamber of the engine.

The height adjusting bolt (5) adjusts the height of the center electrode (2). It is a hollow rod like structure. It is removably fitted into the plug shell (3). The height adjusting bolt (5) consists of a plane outer surface (51) along around half of its length and remaining half of the length (52) consists of threaded structure. The diameter of the portion (51) having plane outer surface is less than the portion (52) having threaded structure. The threaded structure of the height adjusting bolt (5) gets fitted into inner threads of the plug-fixing nut (32). By adjusting tightness between plug shell (3) and height adjusting bolt (5), it is possible to adjust the height of the center electrode (2). The threads are provided on the inner surface of the height adjusting bolt (5) along whole of its length. Generally steel material is used for manufacturing of the height adjusting bolt (5).

According to the present invention the ground electrode (4) is C- shaped. It forms the spark plug gap with center electrode (2). The ground electrode (4) is joined by welding to the plug shell (3).

Ground electrode (4) is connected with the first part (31) of the plug shell (3). The C shape of the electrode (4) offers the following advantages:

i. It provides larger sparking area between the ground electrode (4) and center electrode (2). It ensures the occurrence of the proper sparking, ii. It causes complete combustion of air-fuel mixture, iii. It improves the engine efficiency, iv. It also improves the ignition performance.

The ground electrode (4) is made of nickel alloy. Preferably used nickel alloy may includes nickel chrome, nickel steel or any other like material

The combination of washer (9) and locking nut (10) is provided to make the plug shell (3) and height adjusting bolt (5) fit tightly to each other and at the same time maintains the air tightness.

Insulator (6) provides the insulation of the center electrode (2) from the plug shell (3) and height adjusting bolt (5). As shown in figures

4 and 9, insulator (6) is an elongated structure having almost equal diameter along its whole length. Threads (63) are provided over the outer surface of the insulator (6). A longitudinally extending bore (61) is provided at the center of the insulator (6) through which center electrode (2) passes. At one end insulator (6) is connected to terminal nut (12) through center electrode (2) and at other end connected to the outer jacket (7) of the center electrode (2). The deep valley (62) is provided at one end of the insulator (6) to accommodate one end of the outer jacket (7) so that the outer jacket (7) gets tightly fitted with the insulator (6). The outer threads of the insulator (6) get fitted into the inner threaded structure of the height adjusting bolt (5).

The insulator (6) is made of the plastic material and more preferably of the Teflon. The material being used for the insulator (6) depends upon the temperature and voltage ranges to be faced by the insulator (6). The advantages of using Teflon for insulator (6) are as follows:

i. It is chemically resist. ii. It can withstand high temperature and current, iii. It has low surface coefficient of friction. iv. It provides high impact strength. v. It is cheaper as compared to the conventional material being used for the insulator (6) of the spark plug. The present invention provides adjustable center electrode (2). As shown in figure 7, the center electrode (2) is a rod like structure made of copper, nickel iron, chromium or precious metals. The one end of the center electrode (2) is connected to the terminal nut (12) and other end is provided in the close proximity of the ground electrode (4). The height of the center electrode can be adjusted by the height adjusting bolt (5). Center electrode at top consists of circular head (21) and at bottom the ridged surface (23). The head (21) of the center electrode (2) is in the close proximity with ground electrode (4). These both head (21) and ground electrode . (4) creates spark plug gap. The middle portion (22) of the center electrode is having plane surface. The diameter of the head of center electrode is greater than the diameter of middle portion (22) of the center electrode (2). The center electrode (2) conducts the electricity from the ignition cable hooked to one end of the plug to the spark plug (1) gap at other end. The height adjustment feature of the center electrode (2) increases the life and avoids the frequent replacement of the spark plug (l).This is because after particular level of wear and tear of the head of the center electrode by moving center electrode upwardly by height adjusting bolt (5), the proper spark plug gap can be maintained. Hence by adjusting height of the center electrode as per need one can use the spark plug for many years. Outer jacket (7) is provided for covering the middle portion (22) of the center electrode (2). As shown in figure 8, the outer jacket (7) is elongated in construction and tapered at one end. A longitudinally extending bore (73) is provided at the center of the outer jacket

(7). The bores (73) of the outer jacket (7) and bore (61) of the insulator (6) have the same diameter. The diameter of the head of the center electrode (2) is greater than the bore diameter of the insulator (6) and outer jacket (7). The center electrode (2) is inserted from the top into the bores of the outer jacket (7) and insulator (6). Due to greater diameter of the head (21), center electrode (2) can pass through insulator (6) and jacket (7) except its head portion.

The outer jacket (7) is removably accommodated in the inner threads of the height adjusting bolt. The outer jacket (7) ensures full insulation of the center electrode (2) from the plug shell (3) and height-adjusting bolt (5). Threads are provided on the outer surface of the outer jacket (7) except in the tapered portion. The tapered portion (71) has plane outer surface. The end of the non tapered portion of the outer jacket (7) gets tightly fitted into deep valley (620 of insulator (6). The outer jacket (7) protects center electrode

(2) from heat and corrosion. The jacket is made of ceramic material. The terminal nut (12) is connected at one end to a high-tension cord through which high voltage current from the ignition system flows. At other end it is connected to ridged portion (23) of the center electrode (2).

ADVANTAGES OF THE SPARK PLUG OF THE PRESNET

INVENTION

i. It provides an adjustable center electrode, with spark point at one end that maintains required spark gap between ground electrode and center electrode for smooth running of engine and also offers longer operational life. It provides C-shaped ground electrode offering higher sparking area there by providing higher sparking for complete combustion of air-fuel mixture making the sparking plug efficient.

ii. It generates a strong flame causing complete combustion of air-fuel mixture in turn generates sufficient power for the combustion engine.

iii. Since parts are separable from each other, it is very easy to clean and maintain the spark plug. This feature in turn increases power of engine and fuel efficiency. iv. It ensures complete combustion of air-fuel mixture which reduces misfire to a great extent and thus prevents unburned fuel to clog the exhaust system.

INDUSTRIAL APPLICABILITY

The purpose of the spark plug is to provide a place for an electric spark that is hot enough to ignite the air/fuel mixture inside the combustion chamber of an internal combustion engine. This is done by a high voltage current arcing across a gap on the spark plug. The spark plug of the present invention is widely used in the automobile industry. It is used in the engine's combustion chamber to ignite the fuel-air mixture. It is also used to remove heat from the combustion chamber. The spark plug works as a heat exchanger by pulling unwanted thermal energy from the combustion chamber and transferring heat to the engines cooling system. Spark plug can also be used in other application such as furnaces where a combustible mixture is to be ignited.

Although the present invention has been described with respect to specific, preferred embodiments, various changes and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompasses such changes and modifications as fall within the scope of the appended claims.

Claims

1. A spark plug for an internal combustion engine comprising:

center electrode having an elongated rod like structure being lies lengthwise within the plug and conducts electricity from the ignition cable hooked to one end of the plug to the electrode gap at other end, said center electrode comprises circular head at top, ridged surface at bottom and plane surface in between said head and ridged surface, said head having diameter greater than diameter of the remaining portion of said center electrode; height adjusting bolt being removably fitted inside the plug shell to adjust the height of said center electrode as per the need, said bolt having upper portion and bottom portion, said upper portion having plane outer surface and said bottom portion having threads over the outer surface, wherein bottom portion of said height adjusting bolt get fitted inside the threads of the inner surface of the plug shell, said bolt comprises threads over inner surface along whole length of the bolt;

outer ceramic jacket to cover the plane surface of the center electrode and being removably fitted into the height adjusting bolt, said outer jacket is elongated, tapered at one end and having longitudinally extending bore at the center, said outer jacket having threads over outer surface except in the tapered region, wherein said threads of the outer jacket fitted into the inner threads of the height adjusting bolt;

2. The spark plug as claimed in claim lwherein diameter of bores of insulator and outer jacket is same.

3. The spark plug as claimed -in claim 2 wherein diameter of the head of the center electrode is greater than the diameter of bores of outer jacket and insulator.

4. The spark plug as claimed in claim 1 wherein insulator is made of Teflon.

5. The spark plug as claimed in claim 1 wherein ground electrode is made of nickel alloy.

6. The spark plug as claimed in claim 5 wherein ground electrode is made of nickel chrome.

7. The spark plug as claimed in claim 5 wherein ground electrode is made of nickel steel.

8. The spark plug as claimed in claim 1 further comprises gasket for ensuring tight fitting of spark plug and cylinder head of the engine with each other.

9. The spark plug as claimed in claim 1 further comprises combination of washer and lock nut to make the plug shell (3) and height adjusting bolt (5) fit tightly to each other.

10. The spark plug for internal combustion engine such as herein before described and illustrated with reference to accompanying drawings.