Ignition system and igniter having ruthenium ground electrode and platinum-iridium alloy center electrode
An igniter for a gas turbine engine has a shell; an insulator secured within said shell; a center electrode secured within said insulator and electrically isolated from said shell by said insulator, said center electrode having a firing tip formed from a platinum-iridium (PtIr) alloy and having a diameter of at least 0.09 inches; and a ground electrode mounting on said shell and terminating at a firing end of the igniter that is spaced from the firing tip by a gap, said ground electrode having at least one pin comprising ruthenium (Ru) or a ruthenium alloy. The igniter is advantageously used with an ignition system having a positive polarity pulse output.
1 . An igniter for use with a positive polarity exciter of a gas turbine engine, comprising:
a shell;
an insulator secured within said shell;
a center electrode secured within said insulator and electrically isolated from said shell by said insulator, said center electrode having a firing tip formed from a platinum-iridium (PtIr) alloy that accepts electrons from the positive polarity exciter and having a diameter within a range that is about 0.12 inches; and
a ground electrode mounted on said shell and terminating at a firing end of the igniter that is spaced from the firing tip by a gap, said ground electrode having at least one pin comprising ruthenium (Ru) or a ruthenium alloy and having a diameter in the range of 0.022 inches to 0.122 inches.
2 . The igniter of claim 1 , wherein the firing tip has a diameter of 0.11-0.15 inches.
3 . The igniter of claim 1 , wherein the PtIr alloy comprises a mix of platinum and iridium in the range of Pt70Ir30 to Pt99Ir1.
4 . The igniter of claim 1 , wherein the PtIr alloy comprises a mix of platinum and iridium in the range of Pt80Ir20 to Pt95Ir5.
5 . The igniter of claim 1 , wherein the PtIr alloy comprises a mix of platinum and iridium in the range of Pt85Ir15 to Pt95Ir5.
6 . The igniter of claim 1 , wherein the ground electrode comprises a plurality of pins each having a diameter of about 0.072 inches.
7 . The igniter of claim 6 , wherein each of the pins comprises at least 99.9% ruthenium.
8 . An ignition system comprising the igniter of claim 1 .
9 . An igniter for a gas turbine engine, comprising:
a shell;
an insulator secured within said shell;
a center electrode secured within said insulator and electrically isolated from said shell by said insulator, said center electrode having a firing tip formed from a platinum-iridium (PtIr) alloy and having a diameter of at least 0.09 inches; and
a ground electrode mounted on said shell and terminating at a firing end of the igniter that is spaced from the firing tip by a gap, said ground electrode having at least one pin comprising ruthenium (Ru) or a ruthenium alloy;
wherein the firing tip has a diameter of 0.12 inches, the PtIr alloy comprises Pt90Ir10, the pins have a diameter of 0.072 inches, and the ruthenium comprises at least 99.9% ruthenium.
10 . The ignition system of claim 8 , further comprising a positive polarity exciter and an ignition lead connected at one end to the exciter and at another end to the igniter.
11 . The ignition system of claim 10 , wherein:
the PtIr alloy comprises a mix of platinum and iridium in the range of Pt70Ir30 to Pt99Ir1; and
the ground electrode comprises a plurality of pins each comprising at least 99.9% ruthenium and having a diameter in the range of 0.022 inches to 0.122 inches.
12 . An ignition system, comprising:
a unipolar positive polarity exciter that outputs positive polarity spark pulses;
an ignition lead that connects to the exciter to receive and transmit the spark pulses; and
an igniter that connects to the ignition lead to receive the spark pulses from the exciter, wherein the igniter comprises:
a shell;
an insulator secured within said shell;
a center electrode secured within said insulator and electrically isolated from said shell by said insulator, said center electrode having a firing tip formed from a platinum-iridium (PtIr) alloy and having a diameter of at least 0.10 inches; and
a ground electrode mounted on said shell and terminating at a firing end of the igniter that is spaced from the firing tip by a gap, said ground electrode having at least one pin comprising ruthenium (Ru) or a ruthenium alloy;
wherein the center electrode firing tip and at least one ground electrode pin form a spark gap across which electrons from the positive polarity spark pulses are received by the PtIr firing tip from the at least one Ru or Ru-alloy pin; and
wherein the igniter provides an extended service life from a combination of (1) the applied positive polarity spark pulses to the igniter, (2) the use of PtIr alloy for the firing tip, (3) the use of Ru or Ru alloy for the at least one pin, and (4) the firing tip having a diameter of at least 0.10 inches.