Spark igniter for gas turbine engine
AssigneeGeneral Electric Company
InventorsRobert L. Ponziani, Roy Earwood
Life of this patent
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Abstract
An igniter for a gas turbine engine. An igniter generates a plasma, or spark, somewhat similar to an automotive spark plug. In the invention, an auxiliary electrode is provided, which is embedded in and covered by a solid insulator. During initial phases of operation, no part of the plasma generated contacts the auxiliary electrode. However, eventually, the covering insulation is eroded by the plasma, and the auxiliary electrode becomes exposed and available as a return path for the plasma. The igniter is constructed so that, when this erosion occurs, the lifetime of the igniter is near its end. Detection of this erosion, as by detecting the new current in the auxiliary ground electrode, indicates the approaching end-of-lifetime.
Claims21
Method of operating a fuel igniter in an engine, comprising:
- a) generating a first plasma near a first end of a first electrode;
- b) maintaining a second electrode having a second end;
- c) initially surrounding the second end with a solid insulation;
- and
- d) eroding the solid insulation, to expose the second end, and then generating a second plasma between the first and second electrodes.
Method of operating a fuel igniter in an engine, comprising:
- a) generating a first plasma near a first end of a first electrode;
- b) maintaining a second electrode having a second end;
- c) initially surrounding the second end with a solid insulation;
- and
- d) eroding the solid insulation, to expose the second end, and then generating a second plasma between the first and second electrodes, wherein a current in the second electrode accompanies the second plasma;
- e) detecting the current and issuing a signal in response.
- f) replacing the fuel igniter with a different fuel igniter in response to the signal.
An igniter for a gas turbine engine, comprising:
- a) a first electrode having a tip;
- b) a second electrode which cooperates with the tip to generate a plasma;
- and
- c) a third electrode having no exposure to the tip when the igniter is newly installed, but which develops exposure to the tip after a period of operation and generates a plasma between the first and third electrodes.
An igniter for a gas turbine engine, comprising:
- a) a first electrode, rod-like in configuration, coaxial with an axis;
- b) an insulator surrounding the first electrode, except at a tip of the first electrode, where said tip is exposed;
- c) a second electrode, generally cylindrical in configuration, coaxial with said axis, and surrounding the insulator and the first electrode;
- d) a third electrode having a distal end, embedded in the insulator and completely surrounded by the insulator;
- wherein operation of the igniter causes part of the insulator to erode, thereby causing part of the third electrode to become exposed to the tip and cooperate with the tip to from a plasma.
An igniter for a gas turbine engine, comprising:
- a) a first electrode having a tip;
- b) an insulator surrounding the first electrode;
- c) a second electrode surrounding the insulator, and having an edge which cooperates with the tip to generate a plasma;
- and
- d) a third electrode embedded in the insulator, having no part exposed to the first electrode;
- wherein operation of the igniter causes part of the insulator to erode, thereby causing part of the third electrode to become exposed to the tip and cooperate with the tip to form a plasma.
An igniter for a gas turbine engine, comprising:
- a) a first electrode;
- b) a second electrode which cooperates with the first electrode to generate a plasma;
- c) a third electrode;
- d) a barrier between the third electrode and the first electrode which
- i) blocks auxiliary plasma formation between the first and third electrodes at a time T1, and
- ii) erodes after T1, to enable said auxiliary plasma formation.
An igniter for a gas turbine engine, comprising:
- a) first and second electrodes which
- i) cooperate to generate a plasma;
- and
- ii) wherein plasma generation is accompanied by a change which inhibits later plasma generation;
- and
- b) a third electrode which
- i) becomes available with said change;
- and
- ii) cooperates with either the first or second electrode to generate a plasma.
An igniter for a gas turbine engine, comprising:
- a) a first electrode;
- b) a second electrode which cooperates with the first electrode to generate a plasma;
- and
- c) a third electrode which
- i) is separated from the first electrode by an erodible shield;
- and
- ii) cooperates with the first electrode to generate a plasma when sufficient erosion of the shield occurs.
Dependencies are inferred from the claim text.