US1714521A - Spark plug - Google Patents

Description

y 2 H. SCHLAICH 2 Q SPARK PLUG Fil d July 1, 1926 lNVEN TOR HAW/14W Joe 1mm ATTORNEY Patehted May 28, 1929.

UNITED STA'lES 1,714,521 PATENT OFFICE.

HERMAN SCHLAICH, LONG ISLAND CITY, NEW YORK.

SPARK YLUG.

Application filed July 1,

Thisinvention relates to spark plugs'and is in the nature of an improvement upon the spark plug shown in my pending application Serial No. 103,200, filed April 20, 1926, en-

. element, the arrangement being such that the titled Spark plugs and spark intensifiers.

In said pending application disclosure is made of a spark plug in which one of the electrodes is carried on a thermally responsive to cause pre-ignition when the motor is otherwise in normal condition.

It is a further object of the invention to so construct the spark plug that the s arking gap can never exceed a predetermine length.

In the accompanying drawings forming a part of this specification:

Figure 1 is a sectional plug and Figure 2 1s a bottom plan view thereof. The spark plug comprises a sleeve or body elevation in the spark portion 1 threaded at its lower end for securement to a cylinder of an internal combustion engine. A porcelain insulator 2 is seated in this body portion, being held therein by an externally threaded sleeve nut 3. A conductive wire extends centrally through the insulator sleeve from a bindingterminal 4 at the upper end of the insulator and terminates at its lower end in a central, fixed sparking terminal 5. A second sparking terminal. 6 is carried by a thermally responsive element? consisting ofa bi-metallic strip composed of metals having different (Io-efficients of expansion, said strip being formed as an arc of a volute spiral.

It is a point that this bi-metallic strip is mounted to lie within the lower end of the metallic body portion 1 of the spark-plug.

Forthis purpose said body portion 1 of the spark plug is provided with a smooth-walled,- circular internal rabbet or recess 8 at its lower end. The bi-metallic strip has outwardly projecting, integral fingers 9 which are passed 7 be caused to occur.

body 1 is in contact with a water-cooled part advantage that it is impossi 1926. Serial No. 119,819.

outward through openings in the lower end of the sparkplug body 1 and'clinched at the outer side of said body.

The arrangement is such that when the m0- tor is cold, the lei-metallic strip is out of contact with the spark plug body except at the end thereof which is attached to said body. The bi-metallic strip, however, lies withm the body in position toengage it when expanded by the heat.

With the construction described, the sparking gap is quite short upon the startin of a cold motor, so that the spark may pass re'ely, even though the potential of the spark lug current is low, due to slow rotation of the generator. As the motor warms up, the bimetallic strip is caused to expand, so that the sparking terminal 6 is carried away from the fixed terminal 5 and the length of the sparking gap is increased. i

It is very important that heating of the bimetallic strip to a temperature which would cause pre ignition of the gases be avoided. It is primarily for the purpose of guarding against such faulty operation that the bimetallic strip is mounted within the bodyof the'spark plug. By such mounting, the hi metallic strip is caused to expand into contact throughout its entire length with the bodyl before a temperature of-the lei-metallic strig has been reached at which pre-ignition wou Since the spark plug of the motor, it is always maintained at a safe operating temperature and is also efi'ective to controland limit the temperature of the bismetallic strip when the bi-metallic strip moves into contact with it.

The mountin of the bi-metallic strip within the body or t e spark plug has the further 10 for a careless car owner .or mechanic to distortthe bi-"metallic stripmore than a predetermined, limited distance when attemptingito clean the spark.

plug or to-adjiist the spar Such mounting has the Stfllfflrther advantage of positively limiting the length of the spark ap, so that the passage of the spark when t e motor is warmed up cannot, under any circumstances, be interfered with.

Variations maybe resorted'to Within the scopeLof the invention and parts of the improvements may be used without others. I claim:

1. In asphrk lug for internal combustion motors, the com ination with a spark plug body designed to engage a water-cooled part of the motor, of a fixed sparking terminal, a second sparking terminal spaced therefrom, and a thermally responsive element carrying thesecond. sparking terminal, said thermally responsive element being mounted on the spark plug body and being movableby heating into contact with the spark plug body throughout substantially its entire length before it has been heated to an excessive temperature sufficient to ignite the gases, whereby such excessive heating is avoided.

2. In a spark plug, the combination with a heat dissipating spark plug body, of an arcuate, bi-metallic strip mounted within the body, a sparking terminal carried by said bimetallic strip, said sparking terminal being movable by the bi-mctallic strip in response to temperature changes, and said bi-metallic strip being movable'to contact thespark plug body at a temperature b elow that at which pre-ignition would occur and being conformable in shape to said body at such temperature so that a large area of the bimetallic strip directly engages the heat dissipating body.

3. In a spark plug, the combination with a spark plug body, of a fixed sparking terminal, a movable sparking terminal, and thermally responsive means mounted on the body and carrying the movable sparking terminal, said spark plug body and thermally responsive means being relatively arranged to have extensive contact as the temperature rises and to arrest movement of the movable sparking terminal away from the fixed sparking terminal whereby the length of the spark gap is limited.

i. in a spark. plug, the combination with a fixed sparking terminal, of a second sparking terminal, a thermally responsive element carrying the second sparking terminal and a heat dissipating shell supporting and surrounding the thermally responsive element and engageable therewith over an extended area upon a predetermined distortion thereof to prevent heating of said element to the ignition temperature, and thereby to maintain the motor in efficient operation.

5. In a spark plug, in combination, a fixed sparking terminal, an arcuate second sparking terminal, a thermally responsive element disposed in a plane transverse to the axis of the spark plug and carrying the second sparking terminal said element being distortable by heating to carry the second sparking terminal away from the first, and means surrounding the thermally responsive element and engageable over an extensive area therewith for arresting distortionthereof to limit the length of the spark gap and the heating of the element.

6. In a spark plug, in combination a fixed sparking terminal, a second sparking terminal, an arcuate thermally responsive element disposed in a plane transverse to the axis of the spark plug and carrying the second sparking terminal said element being distortable by changes in temperature to move the second sparking terminal toward and from the first in a direction transverse to the spark plug axis, and a guard surrounding the thermally responsive element to prevent injury thereto and to limit distortion thereof by heating.

7. In a spark plug, in combination, a first sparking terminal, a second sparking terminal, a thermally responsive element carrying the second sparking terminal and distortable by changes in temperature to move the second sparking terminal toward and from the first, and heat dissipating means normally engaging a limited area of the element but arranged, upon a predetermined heating of the thermally responsive element, to engage an extensive area thereof to prevent heatmg to the ignition temperature.

in testimony whereof l have aed my signature to this specification.

HERMAN dClilLhfGH.

near he. t e,

there ninhered patent renieirin eerreetien teller/e:

Granted liter 28, nee, te

it i herehy certified that error appears in printed eneeitiention of the 2, line it, elaini h, ntrihe one the words "an nrennie" and insert inntearl the article "a", and

line-hi, ntrihe net the article "a" and insert instead the nerds an arennte"; and that ihe'eniel ltettere herein should he read with these eerreetiene therein that in eae rnny eeninnn in the recent at the ease in Patent @iiiee.

p heiinn hiene d heeled this 2nd day ei hilly, A. it. fifth.

J, Moore,

CERTIFICATE OF CORRECTION.

Patent No. 1,714,521. Granted May 28 1929, to

HERMAN SGHLAICH.

it is hereby certified that error appears in the erintetl speeiiicatieii of the above numbered patent requiring correction as follows: Page 2, line 50 claim 5 strike out the words "an arcuate" and insert instead the article "a", and line 51, strike out the article "a" and insert instead the words "an arcuate"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Qifice.

Signed and sealed this 2nd day of July, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents.

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