US3242366A - Spark plug with visual indicating discharge bulb - Google Patents

Spark plug with visual indicating discharge bulb Download PDF

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US3242366A
US3242366A US3242366DA US3242366A US 3242366 A US3242366 A US 3242366A US 3242366D A US3242366D A US 3242366DA US 3242366 A US3242366 A US 3242366A
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insulator
electrode
bulb
spark plug
base
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/92—Lamps with more than one main discharge path
    • H01J61/94—Paths producing light of different wavelengths, e.g. for simulating daylight
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/38—Selection of materials for insulation

Definitions

  • This invention relates to spark plugs for internal combustion engines, and more particularly to a spark plug adapted to be a visual indicator for its own sparking operation.
  • a function of the device is to eliminate the customary spark test which is made by disconnecting the high tension cable from the plug and causing a spark between the cable and cylinder block by cranking the motor.
  • indicators have been designed for the purpose of detecting spark plug operation and have taken the form of pencil-like units containing a neon bulb which may be viewed through a window when the device is electrically connected with the spark plug electrodes.
  • Such a device is disclosed in US. Patent 1,957,802.
  • the inconvenience of carrying about an auxiliary test device out weighs the possible advantages it may have.
  • the disadvantage of having to locate the viewing window in the line of sight of the observer has defeated attempts at its wide use. For these reasons, a new approach was needed.
  • spark plugs have relatively thick, opaque insulators. These insulators are designed primarily for their insulative properties and may vary in chemical composition and structure depending on the use of the spark plug. It is now proposed to provide a spark plug the insulator of which being manufactured so that portions thereof become translucent whereby the spark plug serves as its own visual indicator of spark delivery and without adversely affecting the normal function of such insulators.
  • a spark plug having a ceramic insulator provided with translucent wall portions and comprising at least 85 percent alumina is adapted to receive a light source totally concealed therewithin.
  • the light source is electrically energizable and adapted to be connected in series with the spark plug electrodes and when a sparking voltage is applied thereto, the light source is energized illuminating the translucent wall portions producing a glow to indicate to an observer the presence of high voltage at the plug.
  • the spark plug is represented by a longitudinal sectional view and is equipped with a conventional metal shell 12 having threads 14 for threadably mounting the spark plug in an engine. Positioned within the metal shell 12 and secured in the conventional manner is an insulator 16.
  • the insulator is of a ceramic material composed of at least 85 percent alumina and may be glazed or unglazed depending upon the Wishes of the user.
  • the insulator 16 is formed with a center bore using a lower portion 18 of relatively small diameter, a center portion 20 of larger diameter, and a top portion 22 of still larger diameter which serves as a well for receipt of a suitable light source 24 herein illustrated for convenience as a neon lamp having electrode leads 26 projecting into the neon atmosphere and extending from opposite ends and being sealed by the glass bulb 28; the leads being bent to lay against the surface of the glass bulb 28 to establish electrical contact as hereinafter described.
  • a suitable light source 24 herein illustrated for convenience as a neon lamp having electrode leads 26 projecting into the neon atmosphere and extending from opposite ends and being sealed by the glass bulb 28; the leads being bent to lay against the surface of the glass bulb 28 to establish electrical contact as hereinafter described.
  • a metallic electrode 30 having a serrated tip.
  • the electrode center element 32 is sealed in the center portion 20 of the insulator and connects with electrode 30 through a conductive glass seal 34.
  • Coned coil springs 36 receive the tapered ends of the bulb 28 and electrically contact the
  • the bulb 28 is biased by the springs 36 axially in a floating position approximately midway within the upper portion 22 of the insulator body.
  • the springs 36 bear against the terminal 38 in one case and against the top of the electrode center element 32 in the other, thus establishing an electrical path from the terminal 38 to the serrated tip of the center electrode 30.
  • the ground electrode 40 is attached to the metal base 12 and spaced from the serrated tip of the center electrode 30 to establish a firing gap in the well-known manner.
  • the springs 36 also have an important safety function. Should the bulb 28 accidently be broken, the operation of the plug will not be affected. That is, the plug will continue to operate in the manner of a conventional spark gap plug in that the spark will jump across the gap at the springs. This will not occur when the bulb 28 is in position because the electrical path established by the neon lamp electrode leads 26 is of lesser electrical resistance than that of the gap between springs 36.
  • the insulator 16 is of a special construction as will hereinafter appear. It is known that spark plug insulators are formed of a relatively high alumina ceramic material providing electrical insulation between the center wire electrode and the metal base of the spark plug. Such insulators must function in all the ways conducive of efiicient spark plug operation. These requirements, it is assumed, are well-known to those skilled in the art.
  • the present invention is concerned with providing an insulator meeting the above requirements but in addition, providing one having the property of translucence, a property, to our knowledge, heretofore never directly associated with spark plug insulators. This physical property has been taken advantage of in the present invention.
  • the alumina content should be as high as possible and at least in excess of 85 percent alumina.
  • the wall thickness at the rings 42 should, of course, be as thin as possible and still satisfy the engineering requirements of a spark plug insulator. That is, depending upon the particular engine and the type of plug, the insulator thickness in these regions will be designed to provide for maximum translucency under the circumstances. For satisfactory viewing, the current flowing through the neon lamp is in the range of 2 to 15 milliamperes and the insulator thickness is in the range of .03 to .06 inch.
  • Aspark plug comprising a metal base
  • an insulator body adapted to receive a light source mounted on said base and formed of a ceramic material comprising at least 85% alumina, said insulator body having wall portions sufliciently thin to become translucent, said insulator having a stepped centerbore;
  • a terminal mounted on the top of said insulator and having the lower portion thereof extending into the insulator centerbore;
  • a glow discharge bulb of the rare gas type positioned in said oenterbore, said bulb normally providing an electrical series path between said second electrode and said terminal whereby a voltage supplied across said first electrode and said second electrode that is sufiicient to produce an electrical spark therebetween will simultaneously energize said glow discharge bulb sending visible light through said translucent wall portions to indicate spark plug operation;
  • electrode means associated with said bulb operative to establish an auxiliary spark gap in said insulator when said bulb is inoperative thereby enabling said spark plug to continue to operate.
  • a spark plug comprising a metal base
  • a terminal mounted on the top of said insulator and having the lower portionthereof extending into the insulator centerbore;
  • a glow discharge bulb of the rare gas type positioned in said .centerbore and having an upper electrode lead sealed thereto projecting from the upper end of said tube and a lower electrode lead sealed thereto projecting from the lower end of said tube;
  • said upper lead and said lower lead bent to lay against the surface of said bulb so that the ends of said leads face each other;
  • an upper coil spring positioned about the upper end of said bulb and in electrical contact with said upper electrode lead, said upper spring being in electrical contact with the said terminal;
  • means including said springs being operative to establish an auxiliary spark gap when said bulb is inoperative thereby enabling said spark plug to continue to operate.
  • a spark plug comprising a metal base
  • a glow discharge bulb of the rare gas type positioned in said centerbore and having an upper electrode lead sealed thereto projecting from the upper end of said tube and a lower electrode lead sealed thereto projecting from the lower end of said tube;
  • an upper coil spring positioned about'the upper end of said bulb and in electrical contact with said upper electrode lead, said upper spring being in electrical contact with the said terminal;
  • said bulb normally providing an electrical series path between said second electrode and said terminal whereby a voltage supplied across said first electrode and said second electrode that is sufiicient to produce an electrical spark therebetween will simultaneously energize said glow discharge bulb sending visible light through said translucent wall portions to indicate spark plug operation;
  • said springs cooperating to establish an auxiliary spark gap between said upper lead and said lower lead when said bulb is inoperative thereby enabling said spark plug to continue to operate.

Landscapes

  • Ignition Installations For Internal Combustion Engines (AREA)
  • Spark Plugs (AREA)

Description

United States Patent Ofilice 3,242,366 Patented Mar. 22, 1966 3,242,366 SPARK PLUG WITH VISUAL INDICATING DISCHARGE BULB Alfred Candelise and John A. Whaley, Flint, Mich., as-
signors to General Motors Corporation, Detroit, Mich.,
a corporation of Delaware Filed Aug. 15, 1962, Ser. No. 217,086 3 Claims. (Cl. 3131) This invention relates to spark plugs for internal combustion engines, and more particularly to a spark plug adapted to be a visual indicator for its own sparking operation.
A function of the device is to eliminate the customary spark test which is made by disconnecting the high tension cable from the plug and causing a spark between the cable and cylinder block by cranking the motor.
In the past, indicators have been designed for the purpose of detecting spark plug operation and have taken the form of pencil-like units containing a neon bulb which may be viewed through a window when the device is electrically connected with the spark plug electrodes. Such a device is disclosed in US. Patent 1,957,802. In the case of the pencil-like tester, the inconvenience of carrying about an auxiliary test device out weighs the possible advantages it may have. Furthermore, the disadvantage of having to locate the viewing window in the line of sight of the observer has defeated attempts at its wide use. For these reasons, a new approach was needed.
It is known that high production spark plugs have relatively thick, opaque insulators. These insulators are designed primarily for their insulative properties and may vary in chemical composition and structure depending on the use of the spark plug. It is now proposed to provide a spark plug the insulator of which being manufactured so that portions thereof become translucent whereby the spark plug serves as its own visual indicator of spark delivery and without adversely affecting the normal function of such insulators.
In accordance with the invention, a spark plug having a ceramic insulator provided with translucent wall portions and comprising at least 85 percent alumina is adapted to receive a light source totally concealed therewithin. The light source is electrically energizable and adapted to be connected in series with the spark plug electrodes and when a sparking voltage is applied thereto, the light source is energized illuminating the translucent wall portions producing a glow to indicate to an observer the presence of high voltage at the plug.
It is a purpose of the present invention to overcome the disadvantages of the pencil-like tester by the use of the novel insulator which enables an observer to detect the presence of energy at the plug regardless of the position of the insulator with respect to the observers line of sight and regardless of Whether the device is used during daylight or darkness.
These and other objects will appear by reference to the following description and drawing.
Referring to the drawing in detail, the spark plug is represented by a longitudinal sectional view and is equipped with a conventional metal shell 12 having threads 14 for threadably mounting the spark plug in an engine. Positioned within the metal shell 12 and secured in the conventional manner is an insulator 16. The insulator is of a ceramic material composed of at least 85 percent alumina and may be glazed or unglazed depending upon the Wishes of the user. The insulator 16 is formed with a center bore using a lower portion 18 of relatively small diameter, a center portion 20 of larger diameter, and a top portion 22 of still larger diameter which serves as a well for receipt of a suitable light source 24 herein illustrated for convenience as a neon lamp having electrode leads 26 projecting into the neon atmosphere and extending from opposite ends and being sealed by the glass bulb 28; the leads being bent to lay against the surface of the glass bulb 28 to establish electrical contact as hereinafter described. In the lower portion 18 of the insulator is positioned a metallic electrode 30 having a serrated tip. The electrode center element 32 is sealed in the center portion 20 of the insulator and connects with electrode 30 through a conductive glass seal 34. Coned coil springs 36 receive the tapered ends of the bulb 28 and electrically contact the leads 26.
The bulb 28 is biased by the springs 36 axially in a floating position approximately midway within the upper portion 22 of the insulator body. The springs 36 bear against the terminal 38 in one case and against the top of the electrode center element 32 in the other, thus establishing an electrical path from the terminal 38 to the serrated tip of the center electrode 30. The ground electrode 40 is attached to the metal base 12 and spaced from the serrated tip of the center electrode 30 to establish a firing gap in the well-known manner. The springs 36 also have an important safety function. Should the bulb 28 accidently be broken, the operation of the plug will not be affected. That is, the plug will continue to operate in the manner of a conventional spark gap plug in that the spark will jump across the gap at the springs. This will not occur when the bulb 28 is in position because the electrical path established by the neon lamp electrode leads 26 is of lesser electrical resistance than that of the gap between springs 36.
It is to be understood that the insulator 16 is of a special construction as will hereinafter appear. It is known that spark plug insulators are formed of a relatively high alumina ceramic material providing electrical insulation between the center wire electrode and the metal base of the spark plug. Such insulators must function in all the ways conducive of efiicient spark plug operation. These requirements, it is assumed, are well-known to those skilled in the art. The present invention is concerned with providing an insulator meeting the above requirements but in addition, providing one having the property of translucence, a property, to our knowledge, heretofore never directly associated with spark plug insulators. This physical property has been taken advantage of in the present invention.
Accordingly, we have found that it the chemical composition of the ceramic material that goes into the insulator has an alumina content in excess of percent and if insulator wall portions are molded with zones of relatively thin cross section as shown by the circular rings 42 formed in the walls of insulator 16; then a light source of normal intensity situated within such an insulator will send light through the walls becoming visible uniformly to an observer from without. For example, an observer looking at the insulator 16 during the operation of the plug would see a high-frequency flutter or glow at the circular depressions or rings 42. Such a glow would naturally be more apparent during the hours of darkness. However, the preferred embodiment of the invention as illustrated compensates for the loss in contrast during the hours of daylight by providing for shadow casting projections or shoulders 44 which increase the illumination effect at the glow rings 42.
In most cases, the alumina content should be as high as possible and at least in excess of 85 percent alumina. The wall thickness at the rings 42 should, of course, be as thin as possible and still satisfy the engineering requirements of a spark plug insulator. That is, depending upon the particular engine and the type of plug, the insulator thickness in these regions will be designed to provide for maximum translucency under the circumstances. For satisfactory viewing, the current flowing through the neon lamp is in the range of 2 to 15 milliamperes and the insulator thickness is in the range of .03 to .06 inch.
Although the invention has been described with reference to the particular embodiments shown, it is not to be so limited since changes and alterations therein may be made which are within the full and intended scope of the claims which follow.
We claim:
1. Aspark plug comprising a metal base;
an insulator body adapted to receive a light source mounted on said base and formed of a ceramic material comprising at least 85% alumina, said insulator body having wall portions sufliciently thin to become translucent, said insulator having a stepped centerbore;
a first electrode connected to said base;
a second electrode insulated from said base by said insulator and spaced from said first electrode;
a terminal mounted on the top of said insulator and having the lower portion thereof extending into the insulator centerbore;
a glow discharge bulb of the rare gas type positioned in said oenterbore, said bulb normally providing an electrical series path between said second electrode and said terminal whereby a voltage supplied across said first electrode and said second electrode that is sufiicient to produce an electrical spark therebetween will simultaneously energize said glow discharge bulb sending visible light through said translucent wall portions to indicate spark plug operation; and
electrode means associated with said bulb operative to establish an auxiliary spark gap in said insulator when said bulb is inoperative thereby enabling said spark plug to continue to operate.
2. A spark plug comprising a metal base;
an insulator body adapted to receive a light source mounted on said base and formed of a ceramic material comprising at least 85% alumina, said insulator body having wall portions sufficiently thin to become translucent, said insulator body having a stepped centerbore;
a first electrode connected to said base;
a second electrode insulated from said base by said insulator and spaced from said first electrode;
a terminal mounted on the top of said insulator and having the lower portionthereof extending into the insulator centerbore;
a glow discharge bulb of the rare gas type positioned in said .centerbore and having an upper electrode lead sealed thereto projecting from the upper end of said tube and a lower electrode lead sealed thereto projecting from the lower end of said tube;
said upper lead and said lower lead bent to lay against the surface of said bulb so that the ends of said leads face each other;
an upper coil spring positioned about the upper end of said bulb and in electrical contact with said upper electrode lead, said upper spring being in electrical contact with the said terminal;
a lower coil spring positioned about the lower end of said bulb and in electrical contact with said lower lead, said lower coil spring being in electrical contact with said second electrode;
' said bulb normal-1y providing an electrical path between said second electrode and said terminal where-- by a voltage supplied across said first electrode and said second electrode that is sufficient to produce an electrical spark therebetween will simultaneously energize said glow discharge bulb sending visible light through said translucent wall portions to indicate spark plug operation; and
means including said springs being operative to establish an auxiliary spark gap when said bulb is inoperative thereby enabling said spark plug to continue to operate.
3. A spark plug comprising a metal base;
an insulator body adapted to receive a light source mounted on said base and formed of a ceramic material comprising at least alumina, said insulator body having wall portions sufiiciently thin to become translucent, said insulator body having a stepped centerbore;
a first electrode connected to said base;
a second electrode insulated from said base by said insulator and spaced from said first electrode;
a terminal mounted on the top of said insulator and having the lower portion thereof extending into the insulator centerbore;
a glow discharge bulb of the rare gas type positioned in said centerbore and having an upper electrode lead sealed thereto projecting from the upper end of said tube and a lower electrode lead sealed thereto projecting from the lower end of said tube;
said upper lead and said lower lead bent to lay against the surface of said bulb so that the ends of said leads face each other;
an upper coil spring positioned about'the upper end of said bulb and in electrical contact with said upper electrode lead, said upper spring being in electrical contact with the said terminal;
a lower coil spring positioned about the lower end of said bulb and in electrical contact with said lower lead, said lower coil spring being in electrical contact with said second electrode;
said bulb normally providing an electrical series path between said second electrode and said terminal whereby a voltage supplied across said first electrode and said second electrode that is sufiicient to produce an electrical spark therebetween will simultaneously energize said glow discharge bulb sending visible light through said translucent wall portions to indicate spark plug operation; and
said springs cooperating to establish an auxiliary spark gap between said upper lead and said lower lead when said bulb is inoperative thereby enabling said spark plug to continue to operate.
References Cited by the Examiner UNITED STATES PATENTS 1,233,630 10/1914 White 313-129 XR 1,690,702 11/1928 Rotella 313129 XR 2,094,447 9/1937 Doak 313124 XR 2,170,600 8/1939 V011 313201 XR 2,924,642 2/1960 Dart 313144 XR 2,971,110 2/1961 Schmidt 313-221 FOREIGN PATENTS 594,506 6/ 1925 France.
721,722 12/1931 France.
201,225 7/ 1923 Great Britain.
203,403 9/1923 Great Britain.
293,940 3/1932 Italy.
GEORGE N. WESTBY, Primary Examiner.
DAVID J. GALVIN, Examiner.

Claims (1)

1. A SPRAK PLUG COMPRISING A METAL BASE; AN INSULATOR BODY ADAPTED TO RECEIVE A LIGHT SOURCE MOUNTED ON SAID BASE AND FORMED OF A CERAMIC MATERIAL COMPRISING AT LEAST 85% ALUMINA, SAID INSULATOR BODY HAVING WALL PORTIONS SUFFICIENTLY THIN TO BECOME TRANSLUCENT, SAID INSULATOR HAVING A STEPPED CENTERBORE; A FIRST ELECTRODE CONNECTED TO SAID BASE; A SECOND ELECTRODE INSULATED FROM SAID BASE BY SAID INSULATOR AND SPACED FROM SAID FIRST ELECTRODE; A TERMINAL MOUNTED ON THE TOP OF SAID INSULATOR AND HAVING THE LOWER PORTION THEREOF EXTENDING INTO THE INSULATOR CENTERBORE; A GLOW DISCHARGE BULB OF THE RARE GAS TYPE POSITIONED IN SAID CENTERBORE, SAID BULB NORMALLY PROVIDING AN ELECTRICAL SERIES PATH BETWEEN SAID SECOND ELECTRODE AND SAID TERMINAL WHEREBY A VOLTAGE SUPPLIED ACROSS SAID FIRST ELECTRODE AND SAID SECOND ELECTRODE THAT IS SUFFICIENT TO PRODUCE AN ELECTRICAL SPARK THEREBETWEEN WILL SIMULTANEOUSLY ENERGIZE SAID GLOW DISCHARGE BULB SENDING VISIBLE LIGHT THROUGH SAID TRANSLUCENT WALL PORTIONS TO INDICATE SPARK PLUG OPERATION; AND ELECTRODE MEANS ASSOCIATED WITH SAID BULB OPERATIVE TO ESTABLISH AN AUXILIARY SPARK GAP IN SAID INSULATOR WHEN SAID BULB IS INOPERATIVE THEREBY ENABLING SAID SPARK PLUG TO CONTINUE TO OPERATE.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348087A (en) * 1965-04-12 1967-10-17 Gen Motors Corp Visual indicating spark plug with an integral gas lamp
US3839671A (en) * 1973-07-12 1974-10-01 M Gerry Ignition indicator
US5055772A (en) * 1989-09-15 1991-10-08 Gte Laboratories Incorporated High voltage ignition system monitor for spark initiated internal combustion engines

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1233630A (en) * 1917-07-17 Spabk-plug
GB201225A (en) * 1922-04-24 1923-07-24 Arnold Taylor Improvements in and relating to sparking plugs
GB203403A (en) * 1922-06-08 1923-09-10 Owen Evans Jones Improvements in or relating to sparking-plugs for internal-combustion engines
FR594506A (en) * 1924-03-07 1925-09-14 Wankmuller & Co G M B H Spark plug checker
US1690602A (en) * 1924-06-27 1928-11-06 Eastman Kodak Co Optical instrument
FR721722A (en) * 1930-09-20 1932-03-07 Luminescent tube candle controller
US2094447A (en) * 1935-04-26 1937-09-28 Henrietta S Rupp Spark plug
US2170600A (en) * 1938-08-16 1939-08-22 Samuel T Voll Safety clearance lamp
US2924642A (en) * 1957-01-07 1960-02-09 Gen Motors Corp Spark plug and method for forming same
US2971110A (en) * 1959-08-26 1961-02-07 Gen Electric Metal vapor lamps

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1233630A (en) * 1917-07-17 Spabk-plug
GB201225A (en) * 1922-04-24 1923-07-24 Arnold Taylor Improvements in and relating to sparking plugs
GB203403A (en) * 1922-06-08 1923-09-10 Owen Evans Jones Improvements in or relating to sparking-plugs for internal-combustion engines
FR594506A (en) * 1924-03-07 1925-09-14 Wankmuller & Co G M B H Spark plug checker
US1690602A (en) * 1924-06-27 1928-11-06 Eastman Kodak Co Optical instrument
FR721722A (en) * 1930-09-20 1932-03-07 Luminescent tube candle controller
US2094447A (en) * 1935-04-26 1937-09-28 Henrietta S Rupp Spark plug
US2170600A (en) * 1938-08-16 1939-08-22 Samuel T Voll Safety clearance lamp
US2924642A (en) * 1957-01-07 1960-02-09 Gen Motors Corp Spark plug and method for forming same
US2971110A (en) * 1959-08-26 1961-02-07 Gen Electric Metal vapor lamps

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348087A (en) * 1965-04-12 1967-10-17 Gen Motors Corp Visual indicating spark plug with an integral gas lamp
US3839671A (en) * 1973-07-12 1974-10-01 M Gerry Ignition indicator
US5055772A (en) * 1989-09-15 1991-10-08 Gte Laboratories Incorporated High voltage ignition system monitor for spark initiated internal combustion engines

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