US942646A - Electric igniting device. - Google Patents

Description

J. A. & B. A. JEFFREY. ELECTRIC IGNITING DEVICE.

APPLICATION rum) AUG.15, mos.

942,646. Patented Dec.7,1909.

W/T/VESSES:

i I electric discharge,

ive path.

UNITED srn rns PATENT orrioa- JOSEPH ARTHUR JEFFERY AND BENJAMIN ALFRED JETFEBY, 0! SAN FRANCISCG,

CALIFORNIA.

ELECTRIC IGNITING DEVICE.

Specification of Letters Iatent.

Patented Dec. 7, 1909.

Application filed August 15, 1906. Serial No. 330,620;

working within the cylinder of an lnternal combustion engine are subject to fouling, or short circuiting deposits of the products of combustion, adjacent to or between such terminals. These byproducts consisting primarily of carbon, or various combinations therewith, produce a medium of electric conductivity, which will hereinafter be referred to as short circuiting media, as its elements, or constituents are not germane to the invention.

The object of the invention is to provide a whereby accumulations of this short circui'ti'hg media around the electrodes is prevented, or if so deposited, to remove the same by disintegration or otherwise, by the ntlirmal discharge of the current through the Broadly, the invention consists of a spark-- ing device, the exposed area of one mail of the terminals of which are restricted to a degree, where the proximity," or surface contact therewith of a short circuiting medium of lesser conductivity will be insufiicient to carry the current without heating such me-- dium to the point of disintegration.

The ordinary sparking current will freely travel through this short circuiting media taken as a mass; but if the mass be acted upon in small divisions or quantities, the current will heat the same to the point of disintegration or disruption of the conduct- The result can be accomplished in two practical ways.

First: One of the terminals of the circuit passes through an insulated block exposing only a minute area sufiicient for the normal or spark; but so restricted that a particle of the short eircuitin'g media lying in contact therewith would be insultieient to withstand the heat incident to diverting the current through itself. The same is equally true, however large the quantity of such media there-about; since the current acts first upon that small parti ole in immediate contact, which is destroyed leaving a small gap between the terminal and the adjacent mass; which itattacks by a series of arcs,--the heatof which destroys the edge of the surrounding mass until a clear plane is formed, the resistance of which is greater than the gap between the normal terminals of the plug.

' Second: The same effect of dividing the short circuiting medium into small particles can be accomplished by restricting the dimensions of the spark gap. This is attained by terminating the terminal below the surface of the insulating block; providing only a small ca illary opening between such terminal and-t e opposing terminal which is set near such opening clear of the insulating block surface. It is obvious that the quantity of short circuiting media that can accumulate within suchorifice would be too attenuated to carry the current without disruption as before described; and with the same characteristic results. In the meantime, no matter how foul the conditions, the sparking device has not failed in a single instance to perform its function because every .normal closing of the circuit has resulted in a spark either between the normal terminals, or between one of them and the surrounding short circuiting media. Such spark is always suliicien't to ignite the charge Within the cylinder. Experiment has proven that no matter how weak'the current may be (so long as it is sufiicient to cause a discharge at the terminals), it will ac complish the desired results, the requisite time being in ratio to the strength of the current.

In the accompanying drawings :Figure 1 is a longitudinal cross section of a device constructed in accordance with this invention. Fig. 2 is a similar view of a modified form of the same.

In detail the construction consists of the insulating plug A, which is preferablypf porcelain or other vitreous material, with a diametrical enlargement engaging an annular shoulder in the shell 2. The 1nsulating plug is securely held by the bushing 4-, screwed into the shell behind the en largement on the insulator. The function sparking of the insulator is to insulate the terminal 6 from the terminal 3, carried by the shell 2.

The terminal 6 is necessarilyof a substance relatively infusible, and of good electric conductivity, such as platinum, iridium,

the contact cap on the head of the insulator,

The conductor 5 serves to conduct heat away from the terminal 6; and reduces the danger of breaking the attenuated conductor 6,

in assembling the device.

The terminal 6 can protrude slightly from the" insulating plug, but all things considered, the best results are attained with the terminal flush with the-surface of the insulator, as the exposed area is thus reduced merely to the cross section of the wire. Certain, other results accompany the flush terminal, even of larger area, that are not present with a projecting terminal.

The modification shown in Fig. 2 difi ers in general construction only" in that the small orifice 6 is substituted for the terminal 6. The end of the conductor 5 is exposed at the internal end of the orifice to the spark across the gap 7, through said orifice. The results of both constructions are practically identical.

Owing to the hypothetical nature of th science of electricity, it is deemed inadvisable' to attempt a detailed technical or scientific analysis of the effect produced by the discharge present modified form However, the following facts, proven by experiment and under the most trying circumstances, have produced visible effects, and positive results that are best explained by parallel dynamic phenomena. For insoot, the lateral eilect stance. photographs taken across the muzzle of heavy ordnance at the moment of discharge show the combustible gases expanding'latera'lly into the atmosphere, showing in profile a fragmentary hemisphere, fiattened' at the poles as it issues from the muzzle. If the muzzle adjacent the bore is coated with an adherent dust, powder, or of the expanding gases dislodges such adherents by attrition, friction, or otherwise removes itby mechanical force and heat.

A parallel effect results at the discharge point of the terminals. The adjacent dust or soot is removed in identically the same manner and apparently by the same force or forces. The electrical discharge presents the same visible fragmentary spherical zone of action flattened at both poles where it approaches the terminals, but only because the insulator surface is fiat, andthe terminal fiushwith the surface; as is the case with the gun muzzle. When the insulator tapers back from theterminal, or the terof the electric spark by the of sparking device.-

minal projects beyond the surface, these re sults arenotpresent; at least not eilectively so. The sudden expansion of the gases, in the instance of the ordnance; and the sad- .den expansion of'the' lines of electrical. discharge, and their sudden convergence in reentering the circuit at the other pole causes this sphericalzone; the flattened poles of which come into frictional contact with the insulator surface with sufficient velocit and force to dislodge the befouling partic es by chemical, mechanical, and electric force. So important is the phenomenon of the truncated sphere that this device will discharge a spark with both terminals submerged in water. This sudden. lateral expansion of the lines of electrical discharge being sulficient to drive the water away from the terminals by decomposing it, and forming a truncated globule of gas underwater. This serves toprove the working combination between the reduced flush terminal, with the flat surface of the insulator. The surface of the insulator adjacent and over the terminal has been piled up with emery, powdered glass, soapstone,'and other insulating material which has been invariably scattered by the electric discharge between the terminals, as above described.

- The usual diameter of the sparking terminals in devices for igniting the explosive mixtures in internal comb fifty one thousandths of an inch, although such terminals have been made as small as forty one thousandths'of an inch in diameter. We have found, however, that this diameter is fartoo large for the purposes of our invention. Experiment. has roven ustion engines is that a terminal having a diameter 0 {seven one thousandths of an inch gives ekc'ellent results and that is the size we have adopted, although we do not desire to limit ourselves in this particular, as the diameter ean be.

made considerably larger than this and good results secured. We believe, however, that the smaller the wire the more perfectthe results will be. p

The contents of a gas engine cylinder after firing are substantially carbon dioxid, carbon monoxid, moisture, soot, or unconsumed carbon, oil, carbonized oil, minute" metallic particles, etc. Any or all, or any combination thereof would cause an accumulation of. short circuiting media between the terminals of the device. The presence of, these conditions sooner or later render inoperative any terminal area. This is true whether, the short circuiting media are in contact with the terminal, or whether they are adjacent said terminal. If in contact the efliciency of the ignition device is greatly impaired, and it sparker with large exposed is well known that an accumulation of short circuiting media adjacent the terminals, while it will not necessarily prevent the spark from passing between said terminals, will cause such a leakage as will eventually dissipate the force and heat of the spark and render the igniting device useless. These disadvantages are all overcome in our invention, which isnot only constructed to destroy any short circuiting media that might have I collected on the terminals, but

it also serves to prevent the accumulation the body "of of such short circuiting media in proximity to said terminals.

.If a small body of good electrical conductivity is brought into contact with a body of'poor electrical conductivity, and a volume of electricity that ap roximates the carrying capacity of the first, is passed through them, poor electrical conductivity will become heated atthe'point of contact between the two bodies, due to,the resistance that the poor conductor. offers to the passage of the current.

The conditions mentioned are those which we have actually met in practice. As to whether the results are purely electrolytic, chemical, or mechanical, due to atmospheric disturbances we cannot state positively. As

to the reduced terminal area, and flat i n.

sulator surface being responsible for the improved and valuable result there can be no question.

\Ve claim as our invention 1. An electric sparking device lwith sep arated terminals, the exposed area of either of said terminals being restricted to a limit where the proximity or surface contact therewith of a medium of lesser conductivity will be insufficient to carry the-current without heating such medium to the point of disintegration.

2. Anelectric sparking device with separated terminals, and a terminal insulator having an exposed surface, the extremity of either of said terminals being embedded in the exposed surface of the insulator and presenting a restricted area of electric discharge sufficient to cause an impact of the electric spark upon said exposed surface, whereby accumulating short circuiting medla in proximity to said terminals are removed or destroyed by said impact.

3. An electric sparking device with separated terminals, and a terminal insulator, having an exposed surface, said terminals being so arranged as to cause an impact of the electric spark upon the exposed surface of the insulator, theexposed area'of one of said terminals presenting a restricted area of electric discharge sufiicient to cause part of the heat of said spark to be ex ended upon the exposed surface of the insu ator, whereby accumulating short circuiting media in proximity to said terminals are removed by the impact of said. discharge or destroyed by the heat of the latter.

4. An electric sparking device with separated terminals, and a terminal insulator, either of said terminals being flush with said insulating medium and resenting a restricted area ofelectric d scharge suflicient to cause part of the" heat or energy of the electric spark or discharge to become operative in removing short circuiting media on the surface of the insulator ad acent said flush terminal.

5. An electric sparking device with senarated terminals, and a terminal insulator presenting a fiatplane adjacent one of said

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