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: An extruded insulator for a spark plug that is made in a manner that minimizes pores, relics and/or other defects in the insulator microstructure so that the overall dielectric strength or performance of the insulator is improved. The extruded insulator avoids many of the drawbacks associated with such defects, but also has a stepped internal bore for receiving a center electrode. In one embodiment, the extruded insulator is made with a method that uses a multi-phase extrusion process to extrude a ceramic paste around an elongated arbor and form an extruded section, and then removes the arbor from the extruded section to reveal a stepped internal bore.

Abstract: Methods of making an insulator for a condition sensing spark plug and tooling that can be used to perform the various methods, the tooling and methods involving machining one or more channels in the insulator body. The machined channels can be used to accommodate one or more wires from a sensing, display, or processing device. In one particular example, the wires are thermocouple wires used to sense temperature in an internal combustion engine while the spark plug is in use. The methods and tooling may result in channels that are formed more precisely, economically, and efficiently.

Abstract: An electrode material that may be used in spark plugs and other ignition devices including industrial plugs, aviation igniters, glow plugs, or any other device that is used to ignite an air/fuel mixture in an engine. In one embodiment, the electrode material is a ruthenium-based material that includes ruthenium (Ru) as the single largest constituent on a wt % basis, and at least one of rhenium (Re) or tungsten (W). The electrode material may further include one or more precious metals and/or rare earth metals. The electrode material may be used to form the center electrode, the ground electrode, firing tips, or other firing tip 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 spark plug and a method of manufacturing the same, where the spark plug has a metal shell, an insulator, a center electrode, a ground electrode, and a gasket located over a threaded portion of the shell and used to seal the spark plug against a cylinder head. Once the gasket is attached on the spark plug, it is shrunk to become a post-formed gasket with an inner diameter that prevents the post-formed gasket from slipping over a threaded portion of the metallic shell. This process may be carried out with a collet type machine that produces a post-formed gasket that is flat and has a substantially uniform thickness, which can improve the sealability of the gasket. This may be important when the spark plug is installed in a cylinder head made from a lost foam casting process or other process that creates a somewhat porous sealing surface.

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 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: A corona ignition system including a corona igniter, an energy supply, and a frequency detector is provided. The energy supply provides energy to the corona igniter during corona events which are spaced from one another by idle periods, during which no energy is provided to the corona igniter. During the idle periods, the frequency detector obtains the resonant frequency of the corona igniter from at least one of an output voltage and an output current of the energy stored in the corona igniter. The resonant frequency measured during this idle period is dependent only on the corona igniter, and not any other components of the system, and thus is very accurate. The drive frequency of future corona events can then be set based on this accurately measured resonant frequency to achieve a robust corona discharge.

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 method for making an extruded insulator for a spark plug in a manner that minimizes pores, relics and/or other defects in the insulator microstructure so that the overall dielectric strength or performance of the insulator is improved. The method may be used to manufacture an extruded insulator that avoids many of the drawbacks associated with such defects, but also has a stepped internal bore for receiving a center electrode. In one embodiment, the method uses a multi-phase extrusion process to extrude a ceramic paste around an elongated arbor and form an extruded section, and then removes the arbor from the extruded section to reveal a stepped internal bore.

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 method for drying a seal material for use in manufacturing an ignition device, e.g., a spark plug. A free-flowing or loose seal material having a moisture content is provided and brought together with a desiccant for a time sufficient to produce a dry seal material by reducing the moisture content of the loose seal material to a desired level. Thereafter, the dry seal material and the desiccant may be separated from one another so that the dry seal material can be used to form a seal within an internal bore of a 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.