US2874321A - Igniter plug - Google Patents

Igniter plug Download PDF

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Publication number
US2874321A
US2874321A US704466A US70446657A US2874321A US 2874321 A US2874321 A US 2874321A US 704466 A US704466 A US 704466A US 70446657 A US70446657 A US 70446657A US 2874321 A US2874321 A US 2874321A
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United States
Prior art keywords
insulator
ring
ground electrode
recess
igniter
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Expired - Lifetime
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US704466A
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Raymond E Summerer
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Motors Liquidation Co
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Motors Liquidation Co
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Priority to US704466A priority Critical patent/US2874321A/en
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Publication of US2874321A publication Critical patent/US2874321A/en
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    • 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
    • H01T13/52—Sparking plugs characterised by a discharge along a surface

Definitions

  • This invention relates to igniter plugs and has as one of its objectsan improved igniter plug which is adapted to project an especially large holt spark. Another object is to provide an igniter plug particularly suitedl for vuse in rocket and gas turbine engines wherein an especially large hot spark is desirable or essential to assure Vinitiation of combustion.
  • theV invention comprehends an igniter plug wherein the spark gap is recessed from vthe tiring end of the igniter and is formed by ⁇ an annular ground electrode which is spaced, along the axis of the igniter, from the center electrode by a ring-shaped insulator having an inner diameter larger than that of the ground electrode.
  • the annular ground electrode with its relatively small bore, as compared to that of the insulator, serves to restrict passage of the electrical discharge and funnel it to form a pencil of ame which projects a considerable distance from the end of the igniter.
  • one or both of the electrodes are made ofcarbon, portions of which vaporize or spatter during the electrical discharge to'thereby further assist spark propagation.
  • FIG. 1 is a side view in partial section of an igniter constructed in accordance with the invention.
  • Figure 2 is an enlarged view in section ofthe firing end of the igniter shown in Figure 1.V
  • Z is a tubular metal shell internally threaded at the lower or iiring end thereof as shown at 4, and having a mounting ange 5 for securement of the iginiter in the combustion chamber of a gas turbine engine, rocket engine or the like.
  • an elongated ceramic insulator 6 Secured within the shell is an elongated ceramic insulator 6, the lower end of which terminates short of the lower end of the shell.
  • the insulator has a cylindrical through-bore which is of enlarged diameter at the firing end of the plug thereby forming a cylindrical recess as shown at 8.
  • Raised portion 9 on the internal surface of the shell is for the purpose of more snugly receiving and therefore centering insulator 6 within the tubular shell.
  • a metal centerwire 10 is secured within the insulator bore and terminates with a head portion 12 located within the cylindrical recess 8.
  • the upper end 11 of the centerwire forms one of the electrical contact terminals for the igniter, the other contact being formed by the metal shell 2 from which the centerwire is separated by the insulator 6 as shown.
  • a carbon button 14 which forms the center electrode of the igniter plug is positioned within the recess 8 against and in electrical contact with the head portion 12 of the centerwire.
  • This button has a cylindrical projection 16 of reduced diameter which extends snugly within a ring 18 made of ceramic insulating material such as alumina, magnesia, glass or the like.
  • the ground electrode of the igniter is formed by a carbon ring 20 which is partially within recess 8 and positioned con- Patented Feb. 17, 1959 ,ICC r 2 centrically against the insulator ring 18.
  • the length of insulator ring 18 is greater than that of projection 16 on the center electrode, the exposed inner surface 21 of the insulator ring forming a cylindrical-shaped spark gap between the two carbon electrodes.
  • the assembly of the two electrodes and the insulator ring is held securely within the recess 8 by means of a metal ring 22 which has a tapered centerbore converging toward the ground electrode and which is threadedly engaged with the lower end 4 of the shell to thereby bear against the ground electrode.
  • This metal ring 22 also serves to electrically connect the ground electrode to the spark plug shell.
  • 'Four equally spaced slots three of which are shown at 24, 26 and 28 in Figure 2, provide a suitable tool engagement means to thread the ring 22 into the end Y of the shell.
  • the bore of carbon ring 20 is smaller than that of insulator ring 18 such that the ring 2l) serves as a slight restriction to the passage of electrical discharges outwardly from the end of the igniter plug.
  • the bore diameter of ring 20 should be from 33% to 75% of the bore diamelter of insulator ring 18; that is, the bore diameter of ring 20 should be no larger than three-fourths, and no smaller than one-third, of the bore diameter of ring 18.
  • the bore diameter of ring 20 is .06 inch or about 60% of the bore diameter of insulator ring 18 which is .098 inch.
  • the optimum length for the spark gap 21 will, of course, be determined by the amount of electrical energy to be applied. The particular embodiment shown operates on volts, 25 amps, and the length of gap 20 is.025 inch.
  • the spacer ring 18 instead of being made solely of an insulating material, may be made of, or its internal surface provided with a coating of, a semi-conductive material to form a so-called creep-gap or'low tension type spark gap, and the claims are intended to comprehend such a substitution, it being understood that the ring need only be an insulator in the sense that it must electrically separate the electrodes to form a spark gap.
  • An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator member having an opening therethrough and positioned in said recess, a center electrode positioned between said centerwire head portion and one side of said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, and a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned against the otherside of said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, the opening in said ground electrode being smaller than the opening in said insulator member 3 Vso that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
  • An igniter comprising a tubular metal shell, an insulator secured within said shell and havinga centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator member having an opening therethrough and positioned in said re# cess, a center electrode positioned between said centerwire head portion and one side of said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, and a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned against the other side of said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, at least one of said electrodes being made of carbon and the opening in said ground electrode being smaller than the opening in said insulator member so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
  • An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a center electrode positioned between said centerwire head portion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, and an annular ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection so as to form a spark gap therewith, the internal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said insulator ring so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
  • An igniter comprising a tubular metal shell, an elongated insulator secured within said shell, said insulator having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a carbon center electrode positioned between and abutting said centerwire head por tion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, and a carbon ring-shaped ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection to frm a spark gap therewith, the itnernal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said insulator ring so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
  • An igniter comprising a tubular metal shell internally threaded at one end thereof, an elongated insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire Y within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a carbon center electrode positioned between and abutting said centerwire head portion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, a carbon ring-shaped ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection to form a spark gap therewith, and a retainer ring threadedly en gaged with the end of said shell and bearing against said ground electrode to maintain said center electrode, said insulator ring and said ground electrode in assembled relationship, the internal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said
  • An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, an insulator member having an opening therethrough and positioned in said recess, a center electrode positioned in said recess above said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, vand a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned below said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, the opening in said ground electrode being smaller than the opening in said insulator member so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.

Description

United States Patent O IGNrrER PLUG Application December 23, 1957, Serial No. 704,466
6 Claims. (Cl. 313-130) This invention relates to igniter plugs and has as one of its objectsan improved igniter plug which is adapted to project an especially large holt spark. Another object is to provide an igniter plug particularly suitedl for vuse in rocket and gas turbine engines wherein an especially large hot spark is desirable or essential to assure Vinitiation of combustion.
, Brieily theV invention comprehends an igniter plug wherein the spark gap is recessed from vthe tiring end of the igniter and is formed by `an annular ground electrode which is spaced, along the axis of the igniter, from the center electrode by a ring-shaped insulator having an inner diameter larger than that of the ground electrode. The annular ground electrode with its relatively small bore, as compared to that of the insulator, serves to restrict passage of the electrical discharge and funnel it to form a pencil of ame which projects a considerable distance from the end of the igniter. In the preferred embodiment one or both of the electrodes are made ofcarbon, portions of which vaporize or spatter during the electrical discharge to'thereby further assist spark propagation. ,f
Other features,V objectsfand advantages of the invention will appear Vmore clearly from the following detailed description thereof made with reference to the appended drawings in which:
Figure 1 is a side view in partial section of an igniter constructed in accordance with the invention; and
Figure 2 is an enlarged view in section ofthe firing end of the igniter shown in Figure 1.V
Referring now to the drawings, Z is a tubular metal shell internally threaded at the lower or iiring end thereof as shown at 4, and having a mounting ange 5 for securement of the iginiter in the combustion chamber of a gas turbine engine, rocket engine or the like. Secured within the shell is an elongated ceramic insulator 6, the lower end of which terminates short of the lower end of the shell. The insulator has a cylindrical through-bore which is of enlarged diameter at the firing end of the plug thereby forming a cylindrical recess as shown at 8. Raised portion 9 on the internal surface of the shell is for the purpose of more snugly receiving and therefore centering insulator 6 within the tubular shell.
A metal centerwire 10 is secured within the insulator bore and terminates with a head portion 12 located within the cylindrical recess 8. The upper end 11 of the centerwire forms one of the electrical contact terminals for the igniter, the other contact being formed by the metal shell 2 from which the centerwire is separated by the insulator 6 as shown. A carbon button 14 which forms the center electrode of the igniter plug is positioned within the recess 8 against and in electrical contact with the head portion 12 of the centerwire. This button has a cylindrical projection 16 of reduced diameter which extends snugly within a ring 18 made of ceramic insulating material such as alumina, magnesia, glass or the like. The ground electrode of the igniter is formed by a carbon ring 20 which is partially within recess 8 and positioned con- Patented Feb. 17, 1959 ,ICC r 2 centrically against the insulator ring 18. The length of insulator ring 18 is greater than that of projection 16 on the center electrode, the exposed inner surface 21 of the insulator ring forming a cylindrical-shaped spark gap between the two carbon electrodes. The assembly of the two electrodes and the insulator ring is held securely within the recess 8 by means of a metal ring 22 which has a tapered centerbore converging toward the ground electrode and which is threadedly engaged with the lower end 4 of the shell to thereby bear against the ground electrode. This metal ring 22 also serves to electrically connect the ground electrode to the spark plug shell. 'Four equally spaced slots, three of which are shown at 24, 26 and 28 in Figure 2, provide a suitable tool engagement means to thread the ring 22 into the end Y of the shell.
In accordance with the invention, the bore of carbon ring 20 is smaller than that of insulator ring 18 such that the ring 2l) serves as a slight restriction to the passage of electrical discharges outwardly from the end of the igniter plug. For optimum spark propagation, the bore diameter of ring 20 should be from 33% to 75% of the bore diamelter of insulator ring 18; that is, the bore diameter of ring 20 should be no larger than three-fourths, and no smaller than one-third, of the bore diameter of ring 18. In the particular embodiment which is shown in the drawings, but not to exact scale, the bore diameter of ring 20 is .06 inch or about 60% of the bore diameter of insulator ring 18 which is .098 inch. The optimum length for the spark gap 21 will, of course, be determined by the amount of electrical energy to be applied. The particular embodiment shown operates on volts, 25 amps, and the length of gap 20 is.025 inch.
While car-bon is preferred for the electrodes, other referenceto a particular embodiment thereof, 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. For example, if desired the spacer ring 18, instead of being made solely of an insulating material, may be made of, or its internal surface provided with a coating of, a semi-conductive material to form a so-called creep-gap or'low tension type spark gap, and the claims are intended to comprehend such a substitution, it being understood that the ring need only be an insulator in the sense that it must electrically separate the electrodes to form a spark gap.
What is claimed is:
1. An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator member having an opening therethrough and positioned in said recess, a center electrode positioned between said centerwire head portion and one side of said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, and a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned against the otherside of said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, the opening in said ground electrode being smaller than the opening in said insulator member 3 Vso that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
2. An igniter comprisinga tubular metal shell, an insulator secured within said shell and havinga centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator member having an opening therethrough and positioned in said re# cess, a center electrode positioned between said centerwire head portion and one side of said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, and a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned against the other side of said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, at least one of said electrodes being made of carbon and the opening in said ground electrode being smaller than the opening in said insulator member so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
3. An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a center electrode positioned between said centerwire head portion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, and an annular ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection so as to form a spark gap therewith, the internal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said insulator ring so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap. i
4. An igniter comprising a tubular metal shell, an elongated insulator secured within said shell, said insulator having a centerbore enlarged at one end thereof to form a recess, a metal centerwire within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a carbon center electrode positioned between and abutting said centerwire head por tion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, and a carbon ring-shaped ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection to frm a spark gap therewith, the itnernal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said insulator ring so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
5. An igniter comprising a tubular metal shell internally threaded at one end thereof, an elongated insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, a metal centerwire Y within said centerbore terminating with a head portion positioned within said recess, an insulator ring in said recess, a carbon center electrode positioned between and abutting said centerwire head portion and one side of said insulator ring, said center electrode having a projection extending partially through the bore in said insulator ring, a carbon ring-shaped ground electrode positioned concentrically against the other side of said insulator ring and in spaced relationship to said projection to form a spark gap therewith, and a retainer ring threadedly en gaged with the end of said shell and bearing against said ground electrode to maintain said center electrode, said insulator ring and said ground electrode in assembled relationship, the internal diameter of said ground electrode being from 33% to 75% of the diameter of the bore in said insulator ring so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
6. An igniter comprising a tubular metal shell, an insulator secured within said shell and having a centerbore enlarged at one end thereof to form a recess, an insulator member having an opening therethrough and positioned in said recess, a center electrode positioned in said recess above said insulator member, said center electrode having a projection extending partially through the opening in said insulator member, vand a ground electrode having an opening therethrough aligned with the opening in said insulator member and positioned below said insulator member so as to be in spaced relationship to said projection to form a spark gap therewith, the opening in said ground electrode being smaller than the opening in said insulator member so that said ground electrode forms a restriction to the passage of electrical discharges out of the spark gap.
No references cited.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013174A (en) * 1958-01-02 1961-12-12 Bendix Corp Electrical discharge device
US3014151A (en) * 1955-09-29 1961-12-19 Bendix Corp Electrical apparatus
US3134230A (en) * 1961-02-09 1964-05-26 Mccormick Selph Associates Inc Seal for electrical terminal assemblies
US3344304A (en) * 1965-06-23 1967-09-26 Gen Motors Corp Creepage spark type plug having low voltage igniter seal
US4170922A (en) * 1977-09-16 1979-10-16 The United States Of America As Represented By The Secretary Of The Navy Ignitor
US4954743A (en) * 1987-12-15 1990-09-04 Ngk Spark Plug Co., Ltd. Igniter plug structure having semicircular grooves
US20100083942A1 (en) * 2008-10-03 2010-04-08 James Lykowski Ignitor for air/fuel mixture and engine therewith and method of assembly thereof into a cylinder head

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3014151A (en) * 1955-09-29 1961-12-19 Bendix Corp Electrical apparatus
US3013174A (en) * 1958-01-02 1961-12-12 Bendix Corp Electrical discharge device
US3134230A (en) * 1961-02-09 1964-05-26 Mccormick Selph Associates Inc Seal for electrical terminal assemblies
US3344304A (en) * 1965-06-23 1967-09-26 Gen Motors Corp Creepage spark type plug having low voltage igniter seal
US4170922A (en) * 1977-09-16 1979-10-16 The United States Of America As Represented By The Secretary Of The Navy Ignitor
US4954743A (en) * 1987-12-15 1990-09-04 Ngk Spark Plug Co., Ltd. Igniter plug structure having semicircular grooves
US20100083942A1 (en) * 2008-10-03 2010-04-08 James Lykowski Ignitor for air/fuel mixture and engine therewith and method of assembly thereof into a cylinder head
US8365710B2 (en) 2008-10-03 2013-02-05 Federal-Mogul Ignition Company Ignitor for air/fuel mixture and engine therewith and method of assembly thereof into a cylinder head

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