US1548031A - Spark plug - Google Patents

Description

Aug. 4, 1925'. f 1,54s,o31-

n f E. T. FRANZEN 4 SPARK PLUG l Filed March 5, 1923 y INVENTOR' A TTORNE Y Patented Aug. 4, 1925.

UNITED 'STATES ERIC T. FRA-NZEN, on MAPLEWQOD, NEW JERSEY.

SPARK I'LUG.

Application mea March 5, 1923. serial No.. 622,768.

To all whom t may concern.' Y

Be it known that` I, ERIC T. FRANZEN, a citizen of the United States of America, residing at Maplewood, in the county of Essex and State of New Jersey, have invented new and useful Improvements in -Spark Plugs, of which the following is a specilication.

This invention relates to improvements in spark plugs as usedn connection with internal combustion engines and has as one of its objects to providea-spark plug having a spark gap automatically controlledby the heat engendered by explosion vof the gases within the engine cylinder. i A

Another purpose lis to produce a spark plug in which the gap is closed initially due to the relativeV coldk condition ofthe parts and which', becoming heated during operation, causes the gap to open variably according to the temperature ofthe plug and'its associated elements.

A further aim is the provision of a spark plug so designed as to enable .the user to ascertain whether or not the cylinder lin which theplug is used is properly firing, by observation of the variable spark gap, thereby providing a visual means for detecting missing cylinders of internal combustion engines. 1

These several objects are attained by certain structural arrangements in the outer portion of the plug body andconstruction of parts therein, as hereinafter rdescribed and illustrated Vin vthe annexed drawing, forming part hereof, and in which y Y Figure 1 is a side view of a conventional type of spark plug, its upper portion being in section to show the application of an embodiment' of the invention.

FigureI 2 is a transversesectional view taken on line 2 2 of Fig. 1.

Figure 3 is a perspective view showing one form of thermostatic couple as usedin the device and drawn to an enlarged scale.

Figure l is a fragmentary sectional View illustrating the application of a modified form o'f the same.

As will be readily recognized in the drawing a conventional spark plug is shown having a body 10' terminating in a reduced screw-threaded portion 11 and containing an insulator 12 held by the clamp nut 13.

A fixed electrode 14 extends below the threaded base 11 and contained centrally in the insulator is the mating'electrode 15.

The-upper portion of the insulator 12 contains Va circular recess or chamber 16 open at lits outer end which is internally screwthreaded to receive a bushing 17 having an extending liange 18. i

Disposed in the recess 16 is a relatively thin sleeve' 19 made of non-conducting, transparent material, as mica, the same covering 'the innerVV ends of transverse openings 2.0 formed through the insulator.

- Into this recess, concentric with thesleeve 19, 'extends'the upper end of thev electrode 15, v`terminating within the range of the sight openings '20. i

Threadedinto the bushing 17 is a metal plug 21 provided 'witha washer 22 resting on the flange 18 and abovethe washer a clamp nut 2311s threaded on the stud 21.

f A thermostatic' element, generally desiglnatedbythe ,numerall 25 adapted to operateV by changes in temperature, (best shown in detail in Fig. 3) is composed of two metallicplates, 24 and 26, having dilferent ratios of expansion` when subjected to heat,

assteel land brass, is coiled at one end to produce a neck 27, the same being tight l' fitted intoy a hole eccentrically formed in the inner end of the plug 21. e

These plates are permanently and fixedly united over their entirefcontacting surfaces and are so bent as to present the brass surface into position. to make positive electric contact with the adjacent end of the electrode 15.

In the modification shown in F ig.4.-`the bushing is formed with a bottom wall 17 and has an opening at one side through whichthe thermostatic couple .is entered and bent at a. right angle, the same being held rigid by the inner end of the stud 21, the device being in all other respects as previouslydescribed and operates in the same manner.

In starting a cold engine the sparking current will be conveyed from a conductor clamped between the nut 23 and washer 22, to the stud 21 and thence through the thermostatic couple 25 to the electrode 15 direct.

As theengine and its associated parts become heated, the inner ory brass plate 26 f Y delivered spark in a well known manner.

constituting a The spark passing the gap is readily observable through the `openings 20 but entrance of dust, oil, gases and the like are prevented, due to the transparent sleeve 19 enclosing the recess in which the spark gap is confined, and it 'is to be noted that all the several parts are enclose-d within the body of the spark plug, no unsightly pr0 jections or excrescencies being used.

Cbviously when these plugs are in use in a. multi-cylinder engine, the user may, by o'bserving the distances between the couple 25 and the electrode 15 determine the conditions within the cylinders.

@wing to the high temperature attained bythe succession of explosions within the cylinders, it will be understood that the gaps between the electrodes 15 and the couple 25 will, under proper conditions, remain at their maximum, but should any cylinder miss tiring for any appreciable length of time, the gap in its plug will materially shorten so that the user may determine almost instantaneously, the condition.y

Although the foregoing is descriptive of the preferred embodiment or the invention, it will be apparent that minor changes may be made in its construction, without the exercise of invention or conflicting with the scope ot' the claims hereto appended.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. A spark plug having an insulated electrode, a thermostatic couple vforming part oi said electrode, said couple being pendantly supported normally in contact with the electrode and in the circuit leading thereto, said couple being wholly enclosed within the outer portion of the insulator and having its terminal visible through openings in the insulator.

2. A spark plug comprising a body having an electrode, an insulator secured in said body, said insulator having a recess in its upper portion, a second electrode carried by said insulator. and projecting into the recess, a terminal plug ixed in the outer end of said insulator, and a thermostatic couple carried by said plug adapted to directly con- Vvey current to said electrode within the recess or present a gap therebetween.

3. A spark plug comprising abody having a fixed electrode, an insulator carried by said body, said insulator having an open axial recess in its outer end, a second electrode extending into the mentioned recess, a bushing fixed in the outer end of the recess, a terminal plug in said bushing, and a thermal unit fixed in said plug extending into the recess adjacent said second electrode and adapted to convey current thereto, said unit being automatically movable to or from the electrode.

1. A spark plug comprising a body having a lixed electrode, an insulator carried by said body, said insulator having an open axial recess in its outer end and transverse openings intersecting the recess, a transparent sleeve tting the recess, a terminal fixed on the end ot' said insulator over the recess, and a thermal unit attached eccentrica-lly to said terminal adapted to convey current to said second electrode either vby direct contact or through a gap therebetween in accordance with the temperature of said parts. Y

5. 1n a spark plug having an outwardly extending insulator, said insulator containing an axial chamber in its outer portion, an elect-rode having a part entering the chamber, said insulator having transverse openings intersecting the chamber in the plane of the electrode end, a. transparent sleeve in said chamber covering the inner ends of the mentioned openings, a bushing threaded into the open end ot the chamber, a terminal plug in said bushing and a thermal couple fixed in said plug and movable in the chamber to convey current to said electrode.

This speciication signed and witnessed this 19th day of February, 1923. Y

ERIC T. FRrrllZEN` lVitnesses F. NOLL, FnnDK. C. FISCHER.

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