A prechamber spark plug having a housing, which at its front end comprises a prechamber with an ignition electrode arranged therein, wherein the ignition electrode comprises a base and electrode legs protruding from the base, wherein the ignition electrode is machined from a sheet made of an iridium alloy and the legs are bent out of the plane of the base to form a basket shape, characterized in that the ignition electrode, in particular the electrode legs, is/are separated out of the sheet metal by means of laser cutting. Furthermore, a corresponding ignition electrode and a method for producing such an ignition electrode are claimed.

A prechamber spark plug having a housing, which at its front end comprises a prechamber with an ignition electrode arranged therein, wherein the ignition electrode comprises a base and electrode legs protruding from the base, wherein the ignition electrode is machined from a sheet made of an iridium alloy and the legs are bent out of the plane of the base to form a basket shape, characterized in that the ignition electrode, in particular the electrode legs, is/are separated out of the sheet metal by means of laser cutting. Furthermore, a corresponding ignition electrode and a method for producing such an ignition electrode are claimed.

A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and an auxiliary chamber forming portion. The ground electrode faces the center electrode from an outer peripheral side and forms a discharge gap between the ground electrode and the center electrode. An auxiliary chamber is formed inside the auxiliary chamber forming portion. A distance in an axial direction between the discharge gap and a distal end of the auxiliary chamber is equal to or greater than a maximum wall thickness of the auxiliary chamber forming portion. The auxiliary chamber forming portion includes injection holes. The injection holes are formed in a state where openings on an outer side are located closer to a distal end than openings on the auxiliary chamber side. At least one of the injection holes is an injection hole in the axial direction formed along an axial direction of a plug. When viewed in the axial direction of the spark plug, a center of the axial injection hole is eccentric from a central axis of the spark plug toward the discharge gap.

A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and an auxiliary chamber forming portion. The ground electrode faces the center electrode from an outer peripheral side and forms a discharge gap between the ground electrode and the center electrode. An auxiliary chamber is formed inside the auxiliary chamber forming portion. A distance in an axial direction between the discharge gap and a distal end of the auxiliary chamber is equal to or greater than a maximum wall thickness of the auxiliary chamber forming portion. The auxiliary chamber forming portion includes injection holes. The injection holes are formed in a state where openings on an outer side are located closer to a distal end than openings on the auxiliary chamber side. At least one of the injection holes is an injection hole in the axial direction formed along an axial direction of a plug. When viewed in the axial direction of the spark plug, a center of the axial injection hole is eccentric from a central axis of the spark plug toward the discharge gap.

In a spark plug, at least one injection hole serves as a ground-directed injection hole arranged to face a facing side of a ground electrode. An extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point. The facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is. The closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug. The predetermined angle being an obtuse angle.

In a spark plug, at least one injection hole serves as a ground-directed injection hole arranged to face a facing side of a ground electrode. An extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point. The facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is. The closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug. The predetermined angle being an obtuse angle.

This spark plug includes a cap portion covering a center electrode and an end of a ground electrode from a front side. In a cross section including an axial line, where a pitch of an external thread of a metal shell is X (mm), an axial-line-direction distance between a crest of a rear-end ridge of a full thread portion of an external thread and a rear end of a contact portion of an insulator with which the metal shell contacts directly or via another member is A (mm), an axial-line-direction distance between the rear end of the contact portion and a front end of the insulator is B (mm), and an axial-line-direction distance between the rear end of the contact portion and a seating surface of the metal shell is C (mm), 0<A<4X, B≤15, and C≤3.6 are satisfied.

This spark plug includes a cap portion covering a center electrode and an end of a ground electrode from a front side. In a cross section including an axial line, where a pitch of an external thread of a metal shell is X (mm), an axial-line-direction distance between a crest of a rear-end ridge of a full thread portion of an external thread and a rear end of a contact portion of an insulator with which the metal shell contacts directly or via another member is A (mm), an axial-line-direction distance between the rear end of the contact portion and a front end of the insulator is B (mm), and an axial-line-direction distance between the rear end of the contact portion and a seating surface of the metal shell is C (mm), 0<A<4X, B≤15, and C≤3.6 are satisfied.

A spark plug for an internal combustion engine includes insulating glass having a tubular shape, a central electrode including a tip protruding portion, a housing having a tubular shape, and a plug cover provided over an auxiliary combustion chamber. The plug cover is provided with injection holes through which the auxiliary combustion chamber communicates with the exterior. The central electrode includes a base material and a core material disposed inside the base material and having a higher thermal conductivity than the base material. The core material includes a large diameter portion and a small diameter portion continuously formed on a tip side of the large diameter portion. The small diameter portion has a smaller diameter than the large diameter portion, and includes, in a part of the small diameter portion in an axial direction, a small-diameter columnar portion having a constant diameter. At least a part of the small-diameter columnar portion is disposed further on the tip side of the spark plug than a tip of the insulating glass.

A spark plug for an internal combustion engine includes insulating glass having a tubular shape, a central electrode including a tip protruding portion, a housing having a tubular shape, and a plug cover provided over an auxiliary combustion chamber. The plug cover is provided with injection holes through which the auxiliary combustion chamber communicates with the exterior. The central electrode includes a base material and a core material disposed inside the base material and having a higher thermal conductivity than the base material. The core material includes a large diameter portion and a small diameter portion continuously formed on a tip side of the large diameter portion. The small diameter portion has a smaller diameter than the large diameter portion, and includes, in a part of the small diameter portion in an axial direction, a small-diameter columnar portion having a constant diameter. At least a part of the small-diameter columnar portion is disposed further on the tip side of the spark plug than a tip of the insulating glass.