Abstract: A spark plug having a shell with a ground electrode recess. A ground electrode having an insertion end, a firing end, and a round cross-sectional profile toward the insertion end is inserted into the ground electrode recess of the shell. An attachment portion surrounds at least a portion of the ground electrode and includes a solidified bonding material at a connection interface between the ground electrode and the shell. In some implementations, the ground electrode can have a copper core that extends further into the shell, past the distal end of the insulator. In some embodiments, the ground electrode has a sheath surrounding the copper core that has aluminum and a high weight percentage of nickel.

Abstract: A corona igniter (20) includes a metal shell (32) with a corona reducing lip (38) spaced from an insulator (26) and being free of sharp edges (40) to prevent arcing (42) in a rollover region and concentrate the electrical field at an electrode firing end (48). The corona reducing lip (38) includes lip outer surfaces (88) being round, convex, concave, or curving continuously with smooth transitions (90) therebetween. The corona reducing lip (38) includes lip outer surfaces (88) presenting spherical lip radii (rl) being at least 0.004 inches. The corona igniter (20) also includes shell inner surfaces (104) and insulator outer surfaces (75) facing one another being free of sharp edges (40).

Abstract: A corona igniter assembly 20 comprises an ignition coil assembly 22, a firing end assembly 24, and a metal tube 26 connecting the ignition coil assembly 22 to the firing end assembly 24. A rubber boot 28 is disposed in the metal tube 26 and compressed symmetrically between a coil output member 30 of the ignition coil assembly 22 and an insulator 42 of the firing end assembly 24. Thus, the rubber boot 28 fills any air gaps and provides a hermetic seal between the ignition coil assembly 22 and the firing end assembly 24 to prevent unwanted corona discharge from forming from those air gaps.

Abstract: A spark plug suppressor and a method of producing a spark plug suppressor from a suppressor precursor liquid that may be cured at a temperature below 300° C. The spark plug suppressor may include particles or grains dispersed in a matrix of electrically conducting material, electrically semiconducting material, or electrically non-conducting material. The suppressor may include a conductive glass seal component and a resistive suppressor component. The resistive suppressor component may be at least partially embedded in the glass seal component, and the glass seal component may seal a center electrode of the spark plug, a terminal of the spark plug, or both the center electrode and the terminal.

Abstract: A corona ignition system including a corona igniter, switches, and a programmable controller capable of rapidly adjusting to changes in resonant frequency is provided. Energy at a drive frequency and an output current is provided to the corona igniter. Switches provide energy to the corona igniter at the drive frequency and are activated at different times. The controller obtains the output current provided to the corona igniter, typically once every half cycle, and activates the first switch a predetermined amount of time after a first zero crossing of the output current, wherein the first zero crossing is a zero crossing of the most recent full cycle of the output current. The second switch is activated a predetermined amount of time after a second zero crossing occurring after the first zero crossing. The delay of the system is accounted for by the controller, rather than other components.

Abstract: A spark ignition device includes a ceramic insulator with a metal shell surrounding at least a portion of the ceramic insulator. A ground electrode is attached to the shell. The ground electrode has a ground electrode sparking tip spaced from a central sparking tip by a spark gap. A first terminal is arranged in electrical communication with the central sparking tip and is configured for electrical connection with a power source. The device further includes a second terminal configured for electrical connection with the power source. The second terminal is spaced from the first terminal, with the second terminal being arranged in electrical communication with the first terminal. A heater element brings the first terminal in electrical communication with the second terminal and completes an electrical circuit. The heater element has a resistance greater than the first and second terminals thereby producing a significant source of heat.

Abstract: A corona ignition system for maintaining a drive frequency approximately equal to the resonant frequency of a corona igniter is provided. The system includes a current sensor, at least two cascaded timers which are electrically independent of a controller, and at least two switches. During operation, the current sensor measures the current at an input of the corona igniter. A conditioned current signal including information related to the zero crossings of the current ultimately activates a pair of the timers which in turn control and drive one of the switches. The conditioned current signal is not processed by the controller before driving the switch.

Abstract: A corona igniter comprises an electrode with a central extended member extending along a central axis and a crown extending radially outwardly from the central extended member. The central extended member has an extended length and the crown has a crown length. The extended length is greater than the crown length such that the extended member approaches a piston more closely than the crown. In addition, the firing tips of the crown each present a first spherical radius which is less than a second spherical radius of the central extended member. Thus, if arcing occurs, it forms from the central extended member, rather than from the crown. Accordingly, the firing tips of the crown experience less wear and remain sharp. In addition, due to the sizes of the spherical radii, corona discharge is more likely to form from the firing tips than from the central extended member.

Abstract: A system and method for detecting resonant frequency of a corona igniter concurrent with operation of the corona igniter is provided. The method includes providing a plurality of pulses of energy to the corona igniter, each having a pulse duration and spaced from one another by a deadtime duration during which no energy is provided to the corona igniter. Each pulse duration is ceased before current flowing in the corona igniter crosses zero, and each zero crossing of the current occurs during one of the deadtime durations. The next pulse of energy is provided to the corona igniter in response to the zero crossing of the current. A resonant frequency value is then obtained based on a sum of the pulse and deadtime durations of two consecutive cycles, or the time between zero crossings. The resonant frequency values become more accurate over time, and the drive frequency is adjusted accordingly.

Abstract: A corona igniter (20) comprises a central electrode (22) surrounded by an insulator (24), which is surrounded by a metal shell (26). A ceramic combustion seal (30) is disposed along the gap (32) between a shell lower end shell (52) and the insulator nose region (48) to provide a hermetic seal therebetween. The ceramic combustion seal (30) is typically a bushing, cylinder, or ring formed of sintered alumina. A glass material or glass/ceramic mixture (60) typically adheres the ceramic combustion seal (30) to the shell (26) and the insulator (24). Alternatively, the ceramic combustion seal (30) is brazed to the shell (26), and the glass material or glass/ceramic mixture (60) adheres the ceramic combustion seal (30) to the insulator (24).

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: A spark plug for a gas-powered internal combustion engine, having a center conductor, an insulator surrounding the center conductor, a body surrounding the insulator, a center electrode connected in an electrically conductive manner to the center conductor, and at least one ground electrode that is connected in an electrically conductive manner to the body and forms a spark air gap with the center electrode. A shield that shields the spark air gap in the radial direction of the spark plug is located at the front end of the body. The shield includes multiple shield components that are attached to the front end of the body adjacent to one another in the circumferential direction of the spark plug.

Abstract: A corona igniter (20) includes a metal shell (32) with a corona reducing lip (38) spaced from an insulator (26) and being free of sharp edges (40) to prevent arcing (42) in a rollover region and concentrate the electrical field at an electrode firing end (48). The corona reducing lip (38) includes lip outer surfaces (88) being round, convex, concave, or curving continuously with smooth transitions (90) therebetween. The corona reducing lip (38) includes lip outer surfaces (88) presenting spherical lip radii (r1) being at least 0.004 inches. The corona igniter (20) also includes shell inner surfaces (104) and insulator outer surfaces (75) facing one another being free of sharp edges (40).

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 has a firing pad attached to a center electrode or to a ground electrode. The firing pad is attached via laser welding and has a sparking surface with an overall fused area and an unfused area. In one or more embodiments, the overall fused area is located in part or more inboard of a peripheral edge of the firing pad.

Abstract: A prechamber spark plug for a gas-powered internal combustion engine having: a metallic body, an insulator, a center conductor connected to a center electrode, a ground electrode, and a cap that is attached to a front end of the body and forms a prechamber. The prechamber can be subdivided into a front part and a back part by an imaginary separating plane that is perpendicular to the center conductor at an end face of the center electrode. The front part of the prechamber is located on the front side of the separating plane, and the back part is located inside the body on the back side of the separating plane so that the volume of the back part is larger than the volume of the front part. Apart from its connection to the front part of the prechamber, the back part is closed in a gas-tight manner.

Abstract: A spark plug for a prechamber internal combustion engine, having: a body with a passage and a front end; a center electrode located in the passage and that projects past the front end; an insulator that surrounds a section of the center electrode and has a tapering front end that together with the passage forms a free annular space within the body; a ground electrode with an annular ignition section that surrounds a section of the center electrode located outside the body, forming a spark gap; the ground electrode has a mounting section connected to the front end of the body, and at least two web sections connecting the ignition section to the mounting section; located between the web sections are scavenging ports through which the annular space is in connection with the environment outside the spark plug.

Abstract: A corona igniter assembly 20 comprises an ignition coil assembly 22, a firing end assembly 24, and a metal tube 26 connecting the ignition coil assembly 22 to the firing end assembly 24. A rubber boot 28 is disposed in the metal tube 26 and compressed symmetrically between a coil output member 30 of the ignition coil assembly 22 and an insulator 42 of the firing end assembly 24. Thus, the rubber boot 28 fills any air gaps and provides a hermetic seal between the ignition coil assembly 22 and the firing end assembly 24 to prevent unwanted corona discharge from forming from those air gaps.

Abstract: An industrial spark plug (20) includes a central electrode (24) with a central base (30) formed of a nickel-based material and a central firing tip (32) formed of an iridium-based material. The central firing tip (32) has a tip thickness (tct) of 0.02 to 0.03 inches, a tip diameter (dct) of 0.1184 to 0.1776 inches, and an aspect ratio of 4.736 to 7.104. The central firing tip (32) is electron beam welded to the central base (30) to provide a robust joint therebetween. The central electron beam weld (36) includes a mixture of re-crystallized iridium-based material and re-crystallized nickel-based material extending continuously along and over the entire welding interface. The spark plug (20) also includes a ground electrode (26) with a ground firing tip (38) electron beam welded to a ground base (42).

Abstract: A welding system for welding small precious metal firing tips to spark plug electrodes, such as ground and/or center electrodes. According to one embodiment, the welding system includes a firing tip storage assembly and a firing tip welding assembly, where the firing tip storage assembly uses pressurized gas introduced at the bottom of a part container to float or lift the firing tips so that the firing tip welding assembly can more easily acquire them with a vacuum-driven nozzle that also doubles as a welding electrode. The firing tip welding assembly is mounted to a robotic apparatus that can index or move the firing tip welding assembly between the firing tip storage assembly, a welding station and/or any other suitable positions.