A spark plug is provided that includes an improved jamb nut configuration, which provides improved torque transfer and prevents inadvertent separation of the jamb nut from the remaining components of the spark plug, particularly during removal from the engine head. The spark plug is configured for axial insertion into the plug hole, and may have a non-axisymmetric ground shield that fits into the plug hole, wherein the plug hole is also provided with a complementary non-axisymmetric shape. The spark plug includes a central insulator, which has an inner end surrounding a central electrode and supporting the ground shield, which is mounted on the insulator to support a ground strap adjacent the electrode for forming a spark therebetween. The insulator and ground shield are axially slidable into the plug hole, and the jamb nut is rotatable to fix the spark plug in position in a predefined orientation. The insulator includes a retaining clip outwardly of the jamb nut that permits rotation of the jamb nut relative to the insulator but prevents axial separation of the jamb nut during removal of the spark plug from the engine head. An improved tool is also provided which better distributes torque transfer to the jamb nut and includes a catch to facilitate pulling of the spark plug from the engine head.

A spark plug is provided that includes an improved jamb nut configuration, which provides improved torque transfer and prevents inadvertent separation of the jamb nut from the remaining components of the spark plug, particularly during removal from the engine head. The spark plug is configured for axial insertion into the plug hole, and may have a non-axisymmetric ground shield that fits into the plug hole, wherein the plug hole is also provided with a complementary non-axisymmetric shape. The spark plug includes a central insulator, which has an inner end surrounding a central electrode and supporting the ground shield, which is mounted on the insulator to support a ground strap adjacent the electrode for forming a spark therebetween. The insulator and ground shield are axially slidable into the plug hole, and the jamb nut is rotatable to fix the spark plug in position in a predefined orientation. The insulator includes a retaining clip outwardly of the jamb nut that permits rotation of the jamb nut relative to the insulator but prevents axial separation of the jamb nut during removal of the spark plug from the engine head. An improved tool is also provided which better distributes torque transfer to the jamb nut and includes a catch to facilitate pulling of the spark plug from the engine head.

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).

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).

System and methods for operating a vehicle that includes a boosted engine are described. In one example, a spark plug may be adjusted between two operating states to reduce a possibility of pre-ignition and spark plug fouling. A first operating state may be conducive to operating the engine at light loads. The first operating state may be conducive to operating the engine at higher loads.

System and methods for operating a vehicle that includes a boosted engine are described. In one example, a spark plug may be adjusted between two operating states to reduce a possibility of pre-ignition and spark plug fouling. A first operating state may be conducive to operating the engine at light loads. The first operating state may be conducive to operating the engine at higher loads.

A spark plug having multiple spark gaps, where at least one of the spark gaps is located within a prechamber. The spark plug may include a first center wire assembly, a second center wire assembly, an insulator, a metallic shell, a first sparking area with a prechamber cap and a ground electrode for a prechamber spark gap, and a second sparking area with a ground electrode for a main chamber spark gap. The spark plug is designed to maximize engine performance and/or operation by utilizing the multiple spark gaps, where the prechamber spark gap may be used for certain operating conditions where such a spark gap is advantageous and the separate main chamber spark gap may be used for other conditions where a main chamber spark gap is advantageous.

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.

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.

A spark plug is provided, including a housing, an insulator situated within a housing, the insulator having a longitudinal axis, an insulator foot, body, head, and seat. Inside the housing is a housing seat which is in contact with the insulator seat of the insulator. An inner seal is situated between the housing seat and the insulator seat, so that the inner seal, the housing seat, and the insulator seat form a sealing system. The insulator seat includes a step that has a first section and a second section having an angle γ to one another that is greater than 0° and the first section being parallel to the insulator longitudinal axis. The inner seal is in contact with this first section, so that a radial sealing surface is formed at the insulator.