METHOD AND APPARATUS FOR OPERATING TRAVELING SPARK IGNITER AT HIGH PRESSURE
An ignition circuit and a method of operating an igniter (preferably a traveling spark igniter) in an internal combustion engine, including a high pressure engine. A high voltage is applied to electrodes of the igniter, sufficient to cause breakdown to occur between the electrodes, resulting in a high current electrical discharge in the igniter, over a surface of an isolator between the electrodes, and formation of a plasma kernel in a fuel-air mixture adjacent said surface. Following breakdown, a sequence of one or more lower voltage and lower current pulses is applied to said electrodes, with a low “simmer” current being sustained through the plasma between pulses, preventing total plasma recombination and allowing the plasma kernel to move toward a free end of the electrodes with each pulse.
1 - 6 . (canceled)
7 . A method, comprising:
applying, to at least a pair of electrodes of an igniter, a voltage of amplitude sufficient to cause breakdown to occur between the pair of electrodes, resulting in electrical discharge current in an initiation region sufficient to form a plasma kernel adjacent the initiation region; and
passing at least most of the electrical discharge current through a switching element capable of being switched off with at least 3 Amperes (A) of current therethrough.
8 . The method of claim 7 , wherein the switching element is capable of being switched off with at least 3 to 450 A of current therethrough.
9 . The method of claim 8 , wherein the switching element is capable of being switched off with at least 5 A of current therethrough.
10 . The method of claim 9 , wherein the switching element is capable of being switched off with at least 5-200 A of current therethrough.
11 . The method of claim 10 , wherein the switching element is capable of being switched off with at least 20 A of current therethrough.
12 . The method of claim 11 , wherein the switching element is capable of being switched off with at least 40 A of current therethrough.
13 . The method of claim 7 , further comprising drawing the at least most of the electrical discharge current to and/or from a capacitor.
14 . The method of claim 13 , further comprising switching the switching element to draw the at least most of the electrical discharge current to and/or from the capacitor, passing the at least most of the electrical discharge current through the switching element.
15 . The method of claim 7 , wherein the electrical discharge current flows between the pair of electrodes and through the switching element.
16 . The method of claim 15 , further comprising stepping up a voltage stored in the capacitor to obtain the voltage of amplitude sufficient to cause breakdown to occur between the pair of electrodes.
17 . The method of claim 7 , further comprising switching the switching element off while current therethrough is not zero.
18 . A method, comprising:
applying, to at least two electrodes of an igniter, a voltage of amplitude sufficient to cause breakdown to occur between the at least two electrodes, resulting in electrical discharge current in an initiation region sufficient to form a plasma kernel adjacent the initiation region; and
passing at least most of the electrical discharge current through a thyristor or an IGBT.
19 . The method of claim 18 , comprising passing at least most of the electrical discharge current through the thyristor, wherein the thyristor is a metal-oxide-semiconductor (MOS) controlled thyristor (MCT).
20 . The method of claim 18 , comprising passing at least most of the electrical discharge current through the thyristor, wherein the thyristor is an MCT.
21 . The method of claim 18 , further comprising drawing the at least most of the electrical discharge current to and/or from a capacitor.
22 . The method of claim 21 , further comprising switching the switching element to draw the at least most of the electrical discharge current to and/or from the capacitor, passing the at least most of the electrical discharge current through the switching element.
23 . The method of claim 18 , wherein the electrical discharge current flows between the pair of electrodes and through the switching element.
24 . The method of claim 23 , further comprising stepping up a voltage stored in the capacitor to obtain the voltage of amplitude sufficient to cause breakdown to occur between the pair of electrodes.
25 . The method of claim 18 , further comprising switching the switching element off while current therethrough is not zero.
26 . A circuit, comprising:
a capacitor configured to store a first voltage;
voltage step-up circuitry configured to step up the first voltage to a second voltage of amplitude sufficient to cause breakdown to occur between at least two electrodes of an igniter, resulting in electrical discharge current in an initiation region sufficient to form a plasma kernel adjacent the initiation region; and
a thyristor or an IGBT configured for coupling to the igniter to pass at least most of the electrical discharge current therethrough.