Abstract: A ceramic insulator for surrounding an electrode of an ignition device, such as a corona igniter or spark plug, is provided. The insulator is formed of a ceramic material including alumina in an amount of 28 to 38 wt. %, silica in an amount of 57 to 67 wt. %, and calcium oxide in an amount of 3 to 7 wt. %, based on the total weight of the ceramic material. The ceramic insulator is typically formed by firing a mixture of Kaolin, calcium carbonate, and silica, wherein the calcium carbonate acts as a flux during firing. The ceramic material has a relative permittivity of about 5.5 to 6.5 and thus improves the electrical efficiency of the ignition device. The ceramic material is also capable of withstanding temperatures of 900 to 1000° C. and has excellent thermal shock resistance, making it suitable for use in internal combustion engines.

Abstract: A spark plug has a metal shell, an insulator, a center electrode, and a ground electrode. One or more firing tips can be attached to the center electrode, to the ground electrode, or to both electrodes. The metal shell and ground electrode are attached together by way of one or more laser keyhole welds at an interface of the shell and electrode. Before the laser keyhole welds, resistance welding can be executed for a temporary attachment.

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 spark plug has a shell, an insulator, a center electrode, a ground electrode, and a firing pad. The firing pad is made of a precious metal material and is attached to the ground electrode. The firing pad has a side surface at a peripheral edge that can be flush or nearly flush with a free end surface of the ground electrode. This construction can help improve ignitability and flame kernel growth of the spark plug during a sparking event, and can provide better thermal management at the attached ground electrode and firing pad.

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: An igniter (20) includes an outer insulator (24) formed of an outer ceramic material hermetically sealed to a conductive core (26). The conductive core (26) is formed of a core ceramic material and a conductive component, such as an electrically conductive coating applied to the core ceramic material or metal particles or wires embedded in the core ceramic material. The conductive core (26) is typically sintered and disposed in the green outer insulator (24). The components are then sintered together such that the outer insulator (24) shrinks onto the conductive core (26) and the hermetic seal forms therebetween. The conductive core (26) fills the outer insulator (24), so that the conductive core (26) is disposed at an insulator nose end (34) of the outer insulator (24) and the electrical discharge (22) can be emitted from the conductive core (26), eliminating the need for a separate firing tip.

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 method of making a spark plug electrode includes several steps. One step includes providing an inner core of a ruthenium (Ru) based alloy or an iridium (Ir) based alloy. Another step includes providing an outer skin over a portion or more of the inner core in order to produce a core and skin assembly. The outer skin can be made of platinum (Pt), gold (Au), silver (Ag), nickel (Ni), or an alloy of one of these. Yet another step includes increasing the temperature of the core and skin assembly. And another step includes hot forming the core and skin assembly at the increased temperature.

Abstract: A method of making an electrode material for use 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. The electrode material is a ruthenium-based material that includes ruthenium as the single largest constituent. The disclosed method includes hot-forming a layered structure that includes a ruthenium-based material core, an interlayer having a refractory metal disposed over the ruthenium-based material core, and a nickel-based cladding disposed over the interlayer.

Abstract: A method of manufacturing a spark plug that includes a metallic shell, an insulator, a center electrode, a ground electrode, and a firing pad. The method may include the steps of: applying a first laser beam to attach the firing pad to the ground electrode, and then using a second laser beam from the same laser beam welder to attach the ground electrode to the metallic shell. The laser beam welder may include a high energy density fiber laser for forming key-hole laser welds, as well as a programmable focusing optic (PFO) assembly for redirecting laser beams from one welding site to the other.

Abstract: A spark plug (20) for igniting a mixture of fuel and air of an internal combustion engine comprises a center electrode (22) and a ground electrode (24). At least one of the electrodes (22, 24) includes a body portion (28, 30) formed of thermally conductive material and a firing tip (32, 34) disposed on the body portion (28, 30). The firing tip (32, 34) includes a ceramic material, providing an exposed firing surface (36, 38). The ceramic material is an electrically conductive, monolithic ceramic material. Examples of preferred ceramic materials include titanium diboride, silicon carbide, ternary carbide, and ternary nitride. The ceramic material can also include oxides, borides, nitrides, carbides, silicides, or MAX phases.

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 spark ignition device has a ceramic insulator surrounded by a metal shell. The metal shell extends along a longitudinal axis to a distal end. A center electrode is received in the ceramic insulator and extends along the longitudinal axis. A ground electrode has an attachment end fixed by a weld joint to the distal end of the shell and a free end extending from the distal end to provide a spark gap. The weld joint includes a capacitive pulse discharge weld joint and a laser weld joint, which in combination inhibit material expulsion; provide a reliable, strong attachment of the ground electrode to the shell; provide an improved heat transfer path between the ground electrode and the shell, and facilitate repeatable and accurate positioning of the ground electrode to the shell. The weld joint includes a homogeneous mixture of the metal shell and the ground electrode.

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 method of making an electrode material for use in a spark plug 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. The electrode material is a ruthenium-based material that includes a “fibrous” grain structure. The disclosed method includes hot-forming a ruthenium-based material into an elongated wire that includes the “fibrous” grain structure while intermittently annealing the ruthenium-based material as needed. The intermittent annealing is performed at a temperature that maintains the “fibrous” grain structure.

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: A corona discharge (24) ignition includes an electrode (38) emitting a radio frequency electric field and providing a corona discharge (24) to ignite a combustible mixture. The system includes a controlled high voltage energy supply (52) providing energy to a main energy storage (28) at a first main voltage. A fixed high voltage energy supply (54) provides extra energy to an extra energy storage (26) at a second extra voltage, which is greater than the first main voltage. While the corona discharge (24) is being provided, the energy of the main energy storage (28), but not the extra energy storage (26), is provided to the electrode (38). When the corona discharge (24) switches to arc discharge, the extra energy of the extra energy storage (26) is provided to the corona igniter (22) to enhance the arc discharge and provide reliable ignition until the corona discharge (24) is restored.

Abstract: A spark plug (20) for being threaded into a cylinder head (28) includes a shell (24) with threads (26) disposed at a predetermined angled relative to the ground electrode (34). The position of the threads (26) relative to the ground electrode (34) places the ground electrode (34) in a predetermined position in the combustion chamber (22) and relative to components of the engine, thus allowing the ground electrode (34) to provide a robust and reliable ignition. The threads (26) are formed by a thread forming apparatus (102) that includes an orientation tool (38) to position the ground electrode (34) relative to a thread forming apparatus (102), allowing the thread forming apparatus (102) to form the threads (26) at the desired angle (?).

Abstract: A spark plug having an integral gasoline combustion sensor is disclosed. The spark plug includes a center electrode assembly with a terminal stud at one end and a center electrode with a sparking surface at an opposite end; a generally tubular insulator surrounding the center electrode assembly; a shell surrounding the insulator and having along its length a turn-over on a first end, a barrel having an outer surface and barrel shoulder on a gasket flange thereof, a threaded portion, and a ground electrode; and a piezo sensor assembly located on the barrel shoulder proximate the outer surface of the barrel which includes a lower electrode contact, a piezo transducer, an upper electrode contact, an isolator having a convex upper surface, and an upper bushing which is attached to the barrel.

Abstract: A spark ignition device, metal shell, and methods of construction are provided. The spark ignition device has a ceramic insulator extending along a longitudinal axis and a metal shell. The metal shell extends along the longitudinal axis to a distal end. A center electrode is received in the ceramic insulator and extends along the longitudinal axis. A ground electrode has an attachment end fixed by a weld joint to the distal end of the shell and a free end extending from the distal end to provide a spark gap. The weld joint includes a resistance weld joint and a laser weld joint, which in combination inhibit material expulsion; provide a reliable, strong attachment of the ground electrode to the shell; provide an improved heat transfer path between the ground electrode and the shell, and facilitate repeatable and accurate positioning of the ground electrode to the shell.