A spark plug electrode with an electrode tip formed on an electrode base using an additive manufacturing process, such as a powder bed fusion technique. The spark plug electrode includes an electrode base that at least partially surrounds a heat dissipating core, an electrode tip that is formed on the electrode base and includes a precious metal-based material, and a thermal coupling zone that directly thermally couples the electrode tip to the heat dissipating core. In some examples, the electrode tip is formed on an electrode base that has been cut or severed to expose a portion of the heat dissipating core, such that the electrode tip is formed directly on the heat dissipating core using additive manufacturing.

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 which includes an insulator having an axial hole extending along an axial line, a metallic shell disposed around the insulator, and a center electrode disposed in the axial hole to be located on the forward end side of the axial line is provided. The insulator has a step portion provided on the outer circumferential surface thereof and facing toward the forward end side. The metallic shell has a receiving surface provided on the inner circumferential surface thereof and facing toward the rear end side and with which the step portion is engaged via a packing. A portion of the step portion on the outer circumferential side is a first curved surface being convex toward the forward end side, and a portion of the step portion on the inner circumferential side of the first curved surface is a second curved surface which being convex toward the rear end side.

A spark plug has an insulator having a through hole formed along an axial direction, a center electrode which is partially inserted into a portion of the through hole on a forward end side in the axial direction, and a glass seal portion which is in contact with the insulator and the center electrode within the through hole, in which the glass seal portion contains glass and an electrically conductive substance. The glass contains an Si component and a B component in a total amount of 50 mass % or more, as reduced to SiO.sub.2 and B.sub.2O.sub.3, a Zn component in an amount of 20 mass % to 35 mass % as reduced to ZnO, and an alkali metal component. The glass contains, as the alkali metal component, an Na component in an amount less than 1 mass % as reduced to Na.sub.2O.

An ignition plug includes: an insulator provided with a shaft hole formed therein; a metal fitting caulked to support the insulator from an outer periphery side thereof; and a talc material filled in an annular space provided between an outer peripheral surface of the insulator and an inner peripheral surface of the metal fitting. A first annular member and a second annular member are provided at an end portion of the annular space, the end portion being positioned in a center electrode side along the center axis in the annular space, the second annular member is in contact with the first annular member from an opposite side of the center electrode.

A spark plug includes a central electrode member and an outer electrode member. The central electrode member includes a central base and a plurality of electrode prongs extending in an axial direction from the central base. The outer electrode member surrounds the central electrode member. The outer electrode member includes a wall that is radially spaced from the plurality of electrode prongs to allow a series of electric arcs to form between the wall and the plurality of electrode prongs. The outer electrode member and the central electrode member are sized and positioned relative to one another such that a first rate of wear of the outer electrode member, along a longitudinal axis of the spark plug, is substantially equal to a second rate of wear of the central electrode member along the longitudinal axis.

A spark plug includes a central electrode member and an outer electrode member. The central electrode member includes a central base and a plurality of electrode prongs extending in an axial direction from the central base. The outer electrode member surrounds the central electrode member. The outer electrode member includes a wall that is radially spaced from the plurality of electrode prongs to allow a series of electric arcs to form between the wall and the plurality of electrode prongs. The outer electrode member and the central electrode member are sized and positioned relative to one another such that a first rate of wear of the outer electrode member, along a longitudinal axis of the spark plug, is substantially equal to a second rate of wear of the central electrode member along the longitudinal axis.

A method for manufacturing a prechamber spark plug including an external thread and a cap including at least one through-opening. The method includes: providing the prechamber spark plug without a cap and including a cylindrical circumferential surface for the external thread. Mounting the cap, which includes at least one through-opening, in an arbitrary alignment at the prechamber spark plug, and creating the external thread at the circumferential surface in such a way that a thread start and/or a thread end of the external thread is aligned in relation to the through-opening at a predetermined position.

A method for manufacturing a prechamber spark plug including an external thread and a cap including at least one through-opening. The method includes: providing the prechamber spark plug without a cap and including a cylindrical circumferential surface for the external thread. Mounting the cap, which includes at least one through-opening, in an arbitrary alignment at the prechamber spark plug, and creating the external thread at the circumferential surface in such a way that a thread start and/or a thread end of the external thread is aligned in relation to the through-opening at a predetermined position.