Abstract: A corona igniter (20) comprises a central electrode (22) surrounded by an insulator (26), which is surrounded by a conductive component. The conductive component includes a shell (34) and an intermediate part (36) both formed of an electrically conductive material. An outer surface (50) of the insulator (26) presents a lower ledge (52), and the intermediate part (36) is typically attached to the insulator (26) above the lower ledge (52) prior to inserting the insulator (26) into the shell (34). The conductive inner diameter (Dg) is less than an insulator outer diameter (Dio) directly below the lower ledge (52) such the insulator thickness (ti) increases toward the electrode firing end (40). The corona igniter (20) can be reversed-assembled by inserting an upper end (42) of the insulator into a firing end (56) of the shell.

Abstract: The invention provides a system and method for controlling corona discharge and arc formations during a single corona event, i.e. intra-event control. A driver circuit provides energy to the corona igniter and detects any arc formation. In response to each arc formation, the energy provided to the corona igniter is shut off for short time. The driver circuit also obtains information about the arc formations, such as timing of the first arc formation and number of occurrences. A control unit then adjusts the energy provided to the corona igniter after the shut off time and during the same corona event based on the information about the arc formations. For example, the voltage level could be reduced or the shut-off time could be increased to limit arc formations and increase the size of the corona discharge during the same corona event.

Abstract: An electrically conductive glass seal for providing a hermetic bond between an electrically conductive component and an insulator of a corona igniter is provided. The glass seal is formed by mixing glass frits, binder, expansion agent, and electrically conductive metal particles. The glass frits can include silica (SiO2), boron oxide (B2O3), aluminum oxide (Al2O3), bismuth oxide (Bi2O3), and zinc oxide (ZnO); the binder can include sodium bentonite or magnesium aluminum silicate, polyethylene glycol (PEG), and dextrin; the expansion agent can include lithium carbonate; and the electrically conductive particles can include copper. The finished glass seal includes the glass in a total amount of 50.0 to 85.0 weight (wt. %), and electrically conductive metal particles in an amount of 15.0 to 50.0 wt. %, based on the total weight of the glass seal.

Abstract: The invention provides a system and method for controlling corona discharge. A driver circuit provides energy to the corona igniter and detects any arc formation. Optionally, in response to each arc formation, the energy provided to the corona igniter is shut off for a short time to dissipate the arc. Once the arc dissipates, the energy is applied again to restore the corona discharge. The driver circuit obtains information relating to the corona discharge, such as timing and number of arc formations. A control unit adjusts the energy provided to the corona igniter, shut-off time, or the duration of the corona event based on the information. The adjusted energy levels and duration are applied during subsequent corona events. For example, the voltage level could be reduced or the shutoff time could be increased to limit arc formations and increase the size of the corona discharge during the subsequent corona events.

Abstract: An electrically conductive glass seal for providing a hermetic bond between an electrically conductive component and an insulator of a corona igniter is provided. The glass seal is formed by mixing glass frits, binder, expansion agent, and electrically conductive metal particles. The glass frits can include silica (SiO2), boron oxide (B2O3), aluminum oxide (Al2O3), bismuth oxide (Bi2O3), and zinc oxide (ZnO); the binder can include sodium bentonite or magnesium aluminum silicate, polyethylene glycol (PEG), and dextrin; the expansion agent can include lithium carbonate; and the electrically conductive particles can include copper. The finished glass seal includes the glass in a total amount of 50.0 to 90.0 weight (wt. %), and electrically conductive metal particles in an amount of 10.0 to 50.0 wt. %, based on the total weight of the glass seal.

Abstract: A reversed-assembled corona igniter including an insulator, central electrode, and metal shell, wherein an outer diameter of the insulator increases adjacent a lower end of the metal shell to achieve an electrical advantage is provided. In addition, the insulator maintains strength because is not placed under tension during or after assembly, or once disposed in an engine. To achieve the increase in insulator outer diameter, the insulator includes a lower shoulder adjacent the shell firing end. An intermediate part, such as braze and/or a metal ring, is disposed between the insulator outer surface and the shell adjacent the shell firing end. To prevent tension in the insulator, the insulator can be supported at only one location between the insulator upper end and the insulator lower end, for example along the intermediate part.

Abstract: A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.

Abstract: An electrically conductive glass seal for providing a hermetic bond between an electrically conductive component and an insulator of a corona igniter is provided. The glass seal is formed by mixing glass frits, binder, expansion agent, and electrically conductive metal particles. The glass frits can include silica (SiO2), boron oxide (B2O3), aluminum oxide (Al2O3), bismuth oxide (Bi2O3), and zinc oxide (ZnO); the binder can include sodium bentonite or magnesium aluminum silicate, polyethylene glycol (PEG), and dextrin; the expansion agent can include lithium carbonate; and the electrically conductive particles can include copper. The finished glass seal includes the glass in a total amount of 50.0 to 90.0 weight (wt. %), and electrically conductive metal particles in an amount of 10.0 to 50.0 wt. %, based on the total weight of the glass seal.

Abstract: A spark plug (24) of an internal combustion engine is provided with an integrated capacitor feature to increase the intensity of its spark. The capacitor feature is formed by applying metallic film (62, 64) to the inner (30) and outer surfaces of a tubular insulator (26). The insulator (26) forms a dielectric and sustains an electrical charge when an electrical differential is established between the inner (64) and outer (62) metallic films. The stored electrical charge is discharged with the firing of a spark. The metallic films can be applied as a paint or ink directly to the surfaces of the insulator (26), or can be mixed with a glazing compound to form conductive coatings simultaneous with the glazing operation. Ganged (62?) or serpentine (62?) micro-plates can be formed within either or both of the inner and outer metallic films to increase the charge-carrying surface area.

Abstract: The invention provides a system and method for controlling corona discharge and arc formations during a single corona event, i.e. intra-event control. A driver circuit provides energy to the corona igniter and detects any arc formation. In response to each arc formation, the energy provided to the corona igniter is shut off for short time. The driver circuit also obtains information about the arc formations, such as timing of the first arc formation and number of occurrences. A control unit then adjusts the energy provided to the corona igniter after the shut off time and during the same corona event based on the information about the arc formations. For example, the voltage level could be reduced or the shut-off time could be increased to limit arc formations and increase the size of the corona discharge during the same corona event.

Abstract: The invention provides a system and method for controlling corona discharge. A driver circuit provides energy to the corona igniter and detects any arc formation. Optionally, in response to each arc formation, the energy provided to the corona igniter is shut off for a short time to dissipate the arc. Once the arc dissipates, the energy is applied again to restore the corona discharge. The driver circuit obtains information relating to the corona discharge, such as timing and number of arc formations. A control unit adjusts the energy provided to the corona igniter, shut-off time, or the duration of the corona event based on the information. The adjusted energy levels and duration are applied during subsequent corona events. For example, the voltage level could be reduced or the shutoff time could be increased to limit arc formations and increase the size of the corona discharge during the subsequent corona events.

Abstract: A spark plug and method of construction is provided. The spark plug has a generally annular ceramic insulator extending between a terminal end and a nose end. A conductive shell surrounds at least a portion of the ceramic insulator and a ground electrode having a ground electrode sparking surface is operatively attached to the shell. An elongate center electrode has a body extending between opposite ends. The body of the center electrode is formed of a compacted and sintered conductive or semi-conductive ceramic material. The ceramic material of the body comprises at least one oxide. For example, the body of the center electrode can be formed of a perovskite structure or a spinel structure.

Abstract: A corona igniter (20) comprises a central electrode (22) surrounded by an insulator (26), which is surrounded by a conductive component. The conductive component includes a shell (34) and an intermediate part (36) both formed of an electrically conductive material. An outer surface (50) of the insulator (26) presents a lower ledge (52), and the intermediate part (36) is typically attached to the insulator (26) above the lower ledge (52) prior to inserting the insulator (26) into the shell (34). The conductive inner diameter (Dg) is less than an insulator outer diameter (Dio) directly below the lower ledge (52) such the insulator thickness (ti) increases toward the electrode firing end (40). The corona igniter (20) can be reversed-assembled by inserting an upper end (42) of the insulator into a firing end (56) of the shell.

Abstract: A corona ignition system for providing a corona discharge (24) includes an igniter (20) having an electrode (26) with an asymmetrical firing tip (28) relative to an electrode center axis (ae). The firing tip (28) includes a first surface area (A1) facing the fuel injector (42) which is greater than a second surface area (A2) facing a cylinder block (32). The first surface area (A1) presents a projection (60) having a sharp edge, and the second surface area (A2) presents a round outward surface (62). Accordingly, a radio frequency electric field emitted from the first surface area (A1) provides a robust corona discharge (24) in a flammable area at an outside edge (30) of the fuel spray. No electric field is emitted from the second surface area (A2), and no power arcing occurs between the second surface area (A2) and the cylinder block (32).

Abstract: A corona igniter (20) comprises a central electrode (22) surrounded by an insulator (26), which is surrounded by a conductive component. The conductive component includes a shell (34) and an intermediate part (36) both formed of an electrically conductive material. The intermediate part (36) is typically attached to a lower ledge (52) of the insulator outer surface (50) prior to inserting the insulator (26) into the shell (34). The shell firing end (56) is typically aligned with the lower edge and the intermediate firing end. The conductive inner diameter (Dg) is less than an insulator outer diameter (Dio) directly below the lower ledge (52) such the insulator thickness (ti) increases toward the electrode firing end (40).

Abstract: A corona igniter (20) for emitting a radio frequency electric field and providing a corona discharge (24) includes a central electrode (22) at a positive voltage, a grounded metal shell (30), and an insulator (28) with an abruption (34) extending radially outward relative to the central electrode (22). The abruption (34) is typically an increase of at least 15% of a local thickness (t) of the insulator (28) over less than 25% of a nose length (el) of an insulator nose region (74). The abruption (34) is typically one flank (82) of a protrusion or a notch, and the flank (82) faces the shell (30). The abruption (34) reverses the electric field and voltage potential gradient along the insulator outer surface (32), repels charged ions away from the insulator (28), and thus prevents the formation of a conductive path between the central electrode (22) and the shell (22).

Abstract: A corona igniter 20 with improved temperature control at the firing end is provided. The corona igniter 20 comprises a central electrode 24 include a core material 30, such as copper, surrounded by a clad material 32, such as nickel. The core material 30 extends longitudinally between an electrode terminal end 34 and an electrode firing end 36. The core material 30 is disposed at the electrode terminal end 34 and has a core length Ic equal to at least 90% of an electrode length Ie of the central electrode 24. At least 97% of the core length Ic is surrounded by an insulator 26. The electrode diameter is increased, such that a clad thickness tcl of the central electrode 24 is equal to at least 5% of an insulator thickness ti, and a core diameter Dc is equal to at least 30% of the insulator thickness ti.

Abstract: A spark plug and method of construction is provided. The spark plug has a generally annular ceramic insulator extending between a terminal end and a nose end. A conductive shell surrounds at least a portion of the ceramic insulator and a ground electrode having a ground electrode sparking surface is operatively attached to the shell. An elongate center electrode has a body extending between opposite ends. The body of the center electrode is formed of a compacted and sintered conductive or semi-conductive ceramic material. The ceramic material of the body comprises at least one oxide. For example, the body of the center electrode can be formed of a perovskite structure or a spinel structure.

Abstract: A spark plug, a center electrode therefore and method of construction is provided. The spark plug has a generally annular ceramic insulator extending between a terminal end and a nose end. A conductive shell surrounds at least a portion of the ceramic insulator and a ground electrode having a ground electrode sparking surface is operatively attached to the shell. An elongate center electrode has a body extending between opposite ends, wherein the body is compacted and sintered of a conductive or semi-conductive ceramic material. One of the electrode ends provides a center electrode sparking surface to provide a spark gap between the center electrode sparking surface and the ground electrode sparking surface.

Abstract: A corona igniter 20 includes an insulator 28 surrounding a central electrode 24 and a shell 30 surrounding the insulator 28. The shell 30 presents a shell gap 38 having a shell gap width ws between a shell lower end 34 and a shell inner surface 90 or shell outer surface 92. The shell 30 has a shell thickness ts decreasing toward the shell lower end 34 allowing the shell gap width ws to increase toward the shell lower end 34. The shell gap 38 is open at the shell lower end 34 allowing air to flow therein, and the shell gap width ws is greatest at the shell lower end 34. The increasing shell gap width ws enhances corona discharge 22 along the insulator 28 between the central electrode 24 and shell 30.