US1989670A - Spark plug - Google Patents

Description

Feb. 5, 1935. v ANTHONY 1,989,670

SPARK PLUG Filed July 17, 1931 FIG. I.

INVENTOR: FELIX M. ANTHONY ATTORNEY.

Patented Feb. 5, 1935 UNITED STATES PATENT OFFICE one-fourth to Kenneth C.

Gillis and one-fourth to Darrell B. Edwards, both of Oakland, Calif. Application July 17, 1931, Serial No. 551,334

1 Claim.

This invention relates to improvements in spark plugs and more particularly to the electrode terminals of spark plugs for internal combustion motors.

The principal object of the invention is to provide a spark plug that will fire at high working pressures in the modern high speed, high compression automobile motors, at every ignition cycle.

Another object .is to provide a spark of large volume discharged between terminals of considerable area to create a flame-like ignition for the propagation of combustion in the firing chamber.

Other objects and advantages will appear as the description progresses.

In this specification and the accompanying drawing the invention is disclosed in its preferred form. It is to be understood, however, that it is not limited to this form because it may be embodied in other forms within the purview of the claim following the description.

In the one sheet of drawings:

Fig. 1 is a vertical section of a spark plug constructed in accordance with this invention.

Fig. 2 is an end view of the same from below.

Fig. 3 is a fragmentary detail side view in crosssection of a modified form of ground electrode.

Figs, 4 and 5 are horizontal section and plane viewsrespectively of the grid firing surface of the electrodes.

In detail the construction illustrated in the drawing comprises the outer shell 1, having the threaded neck 2 for engaging the cylinder head of the motor, not shown. The shoulder 3 provides for compressing the usual gasket against the cylinder head when the shell is screwed therein by means of the hexagonal portion 4.

The center bore of the top portion is internally threaded to receive the threaded bushing 5, having the hexagonal head 6.

The dielectric core 7 is usually formed of porcelain, compressed mica or other refractory material. This core extends through the shell 1 and is held in fixed position by screwing down the bushing 5 which forces the core against a suitable shoulder provided within the shell 1.

The center electrode 8 extends entirely through the core and engages the conventional terminal 9 fixed in the end of the core. The inner end of the electrode is swaged to form the head 10, the plane of which is transverseto the axis of the electrode. The electrode projects sufiiciently to locate the head beyond the end of the core 7, and beyond the end of the shell also. The mechanical characteristics of spark plugs vary with the type of motor in which they are used, which modifications are applicable to the present invention by those skilled in the art, without departing from the spirit of the invention.

The ground terminal 11 is fixed in the edge of the shell in the usual manner and bent at 12 to bring the end 13 in juxtaposition to the head 10. The end 13 is flattened to form a plate in juxtaposition to the head with its plane parallel with the plane of the head 10.

The opposed surfaces of the head and plate 13 are provided with a multiplicity of depressions 14 and 15 respectively, which form a pair of gridlike surfaces 1617 on the whole areas of the op posed faces of said head 10 and plate 13. Both surfaces are preferably of substantially the same area.

Much of the success of the present invention is ascribable to this grid surface in combination with the parallel planes of these heads and the increased areas of each. Before a spark can bridge the gap, the gas lying between must be ionized. With the conventional type of gap these ions are blown away with the incoming gas stream of the intake cycle, while in this invention, a large number of ions are retained in the recesses of the grid surface. As a consequence, less potential is necessary, and a greater volume of current is permitted to flow across the gap. As the heat increases with the increase of current flowing, a much hotter spark is produced, which is necessary when typical blended gasolines are used.

The value of the above mechanical combination becomes apparent when viewed in connection with the operation of the ignition system. The instant the coils secondary system becomes active, a strong electric field" is produced between and around the points of the plug and the air and gas lying in this field become ionized and the current in a spark is carried across the gap by these ions or charged particles. These ions are usually present in any gas. in very small numbers, and permit the passage of an extremely small current only. This current is so small that ordinarily, air, or any other gas, can be considered as a perfect insulator. But if these ions are present in an electric field between two charged electrodes, they are affected by mechanical forces and will move along the axis of the field. This movement necessarily produces collisions with other molecules, and when the ions have acquired sufiicient momentum, the collision causes disruption of a neutral molecule with the production of twonew electrically charged ions of opposite sign. This action continues to carry on under the influence of the electric field, and collisions'with other molecules produce a further supply of ions at an ever increasing rate, and when sumcient ions become available, the energy of collision materializes as light and heat, and the current passesacross the gap as a spark. It follows, therefore, that any condition, such as the opposed grid surfaces, that will trap and retain' a considerable quantity of such ions will contribute to the improved operation of the spark plug, especially under high pressure conditions.

Heretofore, it has been the practicerto merefiy arrange a gap between the wire electrodes of the older types of internal combustion motors.

In the modern high compression, high speed motors with multiple cylinders, the ignition interval is so short and frequent that the spark plug must be intenseiy responsive or the spark will be quenched by the highly compressed fuel,

to and above 150 pounds pressure.

or the current will find a path of less resistance than the gap;

In actual t isual pressure tests the best spark plugs now available in the open market will begin skipping at from 50 to 65 pounds pressure per square inch and will fail entirely at '70 to '75 pounds. Under the same conditions the Present spark plug continues to fire at pressures up The discharge between the grid surfaces of the head 10 and plate 13 isin the nature of a flaming zone that never fails to propagate a flame in the compressed fuel, even when a weaker spark of the old type will jump through the fuel without producing complete combustion, or fail to spark at all.

It is desirable to keep the bend 12 below the level of the spark gap to drain accumulated oil away fromthe gap between the terminals.

The modifications shown Fig. 3 is only in the mechanical construction of the ground terminal. All corresponding parts are identified with the same reference characters with the addition of X to indicate the modifications.

Having thus described this invention what is claimed and desired to secure by Letters Patent is: l 1

A spark plug having insulated electrodes having confronting terminal surfaces arranged in parallel juxtaposition and having inter-spaced depressions therein so as to form a fiat grid-like lattice surface above the bottom of the depresslons.

Fnmx M. ANTHONY.

Images