US2969500A

US2969500A - Spark plug and ignition indicator system therefor

Info

Publication number: US2969500A
Application number: US675844A
Authority: US
Inventors: Frank S Andert
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-08-02
Filing date: 1957-08-02
Publication date: 1961-01-24
Anticipated expiration: 1978-01-24

Description

Jan. 24, 1961 F'. s. ANDERT 2,959,500

SPARK PLUG AND IGNITION INDICATOR SYSTEM THEREFOR Filed Aug. 2, 1957 IINVENTOR Fran/r 5. Ana/en! ATTORNEY v SPARK PLUG AND IGNITION INDICATOR SYSTEM THEREFOR Frank S. Andert, 877 Randolph, St. Paul, Minn.

Filed Aug. 2, 1957, Ser. No. 675,844

4 Claims. (Cl. 324-47) This invention relates to an improvement in spark plugs and method of operating the same and deals particularly with a spark plug which provides a ready indication of whether or not the spark plug is in operation.

A great number of different types of spark plugs have been produced for a multiplicity of purposes. Some such plugs have been produced which provide an alternate circuit which may be employed in the event one circuit shall fail to operate. The present invention includes a spark plug having a plurality of circuits, one of which acts to supply high tension current to the plug and the other two of which are connected to ground. One of the last mentioned circuits is connected through an indicating light which permits a visual inspection of the operability of the plug so that at any time the operator of an internal combustion engine or the like may see at a glance whether or not all of the spark plugs are operating correctly.

Various test circuits have been employed and some of these circuits have been built into the ignition systems of automobiles and the like. However, those systems with which I am familiar are supplied with current from the vehicle distributor and use this current to provide a visual indication. While such systems show whether or not the spark plugs are being supplied with current, they often do not actually show whether the spark plug is operating. In any event, if they doactually show operation or non-operation of the spark plug, they do this in an indirect manner.

A feature of the present invention resides in the provision of a spark plug having a tubular conductor which extends through the core of the spark plug and which encloses an additional conductor. Ground terminals are also provided in spaced relation to the tubular conductor so that the high tension current will jump between the ground connection and the tubular conductor. The third conductor which is enclosed within the tubular conductor is preferably connected to ground through a lamp capable of withstanding the current employed such as, for example, a neon bulb. As a result, spark may also jump from the tubular connector to the enclosed electrode, this current forming a visual indication of the operability of the plug. As the light will not be illuminated unless the spark is jumping from the high tension terminal, this system provides an actual indication not only that the spark plug is being supplied with current, but also that the spark plug is actually operating. As both the third electrode and the directly grounded electrodes are connected to ground, a spark will be produced regardless of the direction of travel of the spark produced.

A feature of the present invention resides in the provision of a spark plug having three operable electrodes which are arranged in such a manner that while there is a tendency for the spark to jump from the tubular electrode to the directly grounded electrodes, the spark will also jump to the third or enclosed electrode with sufficient regularity to provide a good indication of the operability of the plug. While it is a well known fact that electricity will normally follow the path of least resistance, unusual nited tates Paten "ice results may result when high tension current is involved. Thus, while the general path of electricity is from the tubular electrode to the directly grounded electrodes, there is sufficient discharge of electricity to the third electrode to provide the necessary indication.

A further feature of the present invention resides in the production of a spark plug having an outer grounded shell, a body of porcelain or similar material enclosed within the shell and projecting therefrom, a tubular electrically conductive electrode extending through said insulator body, and an inner conductor enclosed within and insulated from the tubular conductor. This type of spark plug makes the system described possible.

These and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification:

Figure 1 is a cross sectional view through a spark plug showing the novel construction thereof.

Figure 2 is a typical wiring diagram illustrating the manner in which the spark plug shown in Figure 1 may be used.

In general, much of the construction of the spark plug may be conventional. The spark plug is indicated in general by the letter A and includes an outer metallic shell 10 which is preferably hexagonal in shape so that the spark plug may be engaged by a wrench or other suitable tool. The lower portion 11 of the shell 10 is of slightly smaller periphery arid includes external threads 12 by means of which the spark plug may be inserted into the engine block or the like. A shoulder 13 is provided between the hexagonal portion 14 of the spark plug shell and the lower threaded portion 11 thereof, this shoulder permitting the insertion of a sealing washer or gasket between the spark plug body and the engine block.

The lower portion 11 of the shell 10 is of one diameter internally as indicated at 15 and the sleeve or shell 10 is provided with a somewhat larger diameter upper intermediate portion 16, a shoulder 17 thus being formed between the two parts of different diameter. The upper end of the shell 10 is internally threaded as indicated at 19 to accommodate a bushing 20. The bushing 20 is provided with a lower portion having a cylindrical inner surface 21 which is of approximately the same diameter as the inner surface 15 and the coupling is provided with a tapered upper portion 22, the taper being on the inner surface of the coupling.

An insulator body 23 of porcelain or the like is provided with a tapered upper portion 24, a cylindrical portion 25 adjoining the upper tapered portion 24, a larger diameter portion 26 beneath the cylindrical portion 25, and a tapered lower portion 27. Thus, the upper and lower ends of the insulator body are of somewhat smaller diameter than the intermediate portions thereof. The dimensions are such that the coupling 20 is supported with its tapered inner surface 22 encircling the lower portion of the tapered plug surface 24, the cylindrical portion 25 fitting snugly Within the cylindrical inner surface 21 of the coupling 20, the enlarged diameter portion 26 fitting snugly within the larger diameter portion 16 of the shell 10 and with the tapered lower portion 27 of the insulator body enclosed within the lower portion 11 of the shell 10. The insulator body extends with its lower end substantially flush with the lower end of the shell 10.

A tubular conductor 29 is embedded within the porcelain insulator 23, this conductor either being continuous throughout the length of the insulator or incorporating a resistance element 30 between the two

tubular end portions

29 and 31. A spring 32 or other connector may be inserted between the resistance 30 and one of the

tubular parts

29 or 31 so as to provide a continuous electrical connection from end to end of the plug. Spark plugs including resistors have possibly been employed in aircraft engines and the like where the proper operation of the plug is of vital importance. In the event the resistance element is not necessary, the electrode may comprise a single tubular integral body extending from end to end of the plug.

An electrode 33 extends axially through an insulator 34 enclosed within the

tubular electrode

29, 31. The insulation 34 holds the two electrodes in properly spaced relation to provide the necessary insulation effect. The electrode 33 preferably extends slightly below the end of the electrode portion 31 as is indicated, to be more in the path of sparks jumping from the lower end of the tubular electrode 31 and the directly grounded electrode 35. One or more such electrodes 35 may be employed.

The upper end of the tubular conductor 29 is externally threaded and projects above the upper extremity of the insulator body 23. A screw cap 36 or other suitable connector provides a means of connecting the conductor 29 to a flexible conductor such as 37 leading to the distributor. Preferably, the upper end of the electrode 33 projects from the end of the insulator 34 as indicated at 39 and the electrode 39 is connected to a conductive cap such as 49 which may be engaged by a suitable spring connector not illustrated in the drawings.

With reference now to Figure 2 of the drawings, a typical ignition system employing the spark plugs A is indicated, the system being employed in a six cylinder engine for the purpose of illustration. Obviously, the ignition system can be changed or modified as the source of current or the source of the high tension electricity connected to the spark plugs is not of importance in the present invention. However, in the arrangement illustrated, the battery 41 has one terminal grounded as indicated at 42. The other battery terminal is connected by a conductor 43 to one terminal of the low tension winding 44 of a spark coil 45. The other terminal of the coil 44 is connected by a conductor 46 to ground at 47 through a current interrupting device 49 which usually forms a part of the distributor. The current interrupting device 49 normally includes one or'more pairs of breaker points which are operated in timed relation to the distributor to provide a surge of high tension current each time the distributor connects the coil 45 to a spark plug.

The coil 45 also includes a high tension winding 50 connected to ground at 51, the other terminal of the high tension coil extending through the conductor 51' to the arm of the distributor 52. The distributor 52 is successively connected to contacts 53 which extend through the distributor cap or are connected in any suitable way to the spark plugs by the conductor such as 54.

The conductors 54 are normally connected to the spark plug electrodes or conductors 29 while the electrodes 35 are grounded as indicated at 55. The inner or third electrodes 33 are shown connected by conductors 56 to indicator lamps 57, the other terminals of which are grounded as indicated at 59.

From the foregoing description it will be seen that as the engine is operated, the distributor 52 directs current from the coil 50 to the various spark plugs in their proper succession. The major portion of the spark jumps from the tubular electrode 31 to the directly grounded electrode or electrodes 35. However, sufiicient current also jumps to the central electrode 33 to illuminate the associated light 57 to provide an indication that the ignition system to the spark plugs is in operation as well as the spark plug itself. Obviously, unless the spark is jumping the gap between the various electrodes, no indication will take place.

In accordance with the patent statutes, I have described the principles of construction and operation of my improvement in spark plugs, and while I have endeavored to set forth the best embodiments thereof, I desire to have it understood that changes may be made Within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A spark plug including an outer metallic shell, an insulator body supported within said shell, a tubular electrode extending through said insulator body, a second insulator body within said tubular electrode, a second electrode extending through said second insulator Within said tubular electrode, and a third electrode on said out r metallic shell extending transversely to the longitudinal axes of the tubular andsecond electrodes into closely spaced relation with one end of said tubular electrode and the adjacent end of said second electrode.

2. The construction described in claim 1 and in which thesecond electrode within said tubular electrode projects beyond said one end of said tubular electrode.

3. An ignition indicating system in combination with a spark plug having an outer metallic shell, an insulator body supported within said shell, a tubular electrode extending through said insulator body, and an additional electrode extending through said tubular electrode and insulated therefrom, and an electrode on said outer metallic shell extending transversely to the longitudinal axes of said tubular and additional electrodes into closely spaced relation to one end of said tubular electrode and the adjacent end of said electrode extending through said tubular electrode, a source of current connected to said tubular electrode, the shell of said spark plug being grounded, and an indicator light between said electrode extending through said tubular electrode and ground.

4. The construction described in claim 3 and in which said indicating light is a neon light.

References Cited in the file of this patent UNITED STATES PATENTS