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.

A spark plug (1) for internal combustion engines has a center electrode (6) arranged along a central axis (2) of the spark plug (1), which electrode (6) is enclosed by an insulator (5) at least in portions, and a housing (9) in which the insulator (5) is received, at least in portions. A gap (20) is formed, at least in portions, between the insulator (5) and the housing (9). The gap (20) is at least partially filled with a material (23) having a thermal conductivity (λ)≥1 W/(m*K).

A spark plug (1) for internal combustion engines has a center electrode (6) arranged along a central axis (2) of the spark plug (1), which electrode (6) is enclosed by an insulator (5) at least in portions, and a housing (9) in which the insulator (5) is received, at least in portions. A gap (20) is formed, at least in portions, between the insulator (5) and the housing (9). The gap (20) is at least partially filled with a material (23) having a thermal conductivity (λ)≥1 W/(m*K).

A prechamber spark plug, including center and ground electrodes, a housing having an external thread, a cap arranged on the housing and together with the housing defines a prechamber, and an insulator which electrically insulates the center electrode from the housing. The external thread has a thread length in the axial direction. The housing is fastened to the insulator at first and second fixing regions so that a first clamping force at the first fixing region acts from the housing on the insulator, and a second clamping force at the second fixing region acts from the housing on the insulator. The first and second clamping forces are directed in opposite directions to one another in the axial direction. A distance between the first and second fixing regions in the axial direction defines a clamping length. A ratio between the thread length and the clamping length is between 0.7 to 1.3.

A prechamber spark plug, including center and ground electrodes, a housing having an external thread, a cap arranged on the housing and together with the housing defines a prechamber, and an insulator which electrically insulates the center electrode from the housing. The external thread has a thread length in the axial direction. The housing is fastened to the insulator at first and second fixing regions so that a first clamping force at the first fixing region acts from the housing on the insulator, and a second clamping force at the second fixing region acts from the housing on the insulator. The first and second clamping forces are directed in opposite directions to one another in the axial direction. A distance between the first and second fixing regions in the axial direction defines a clamping length. A ratio between the thread length and the clamping length is between 0.7 to 1.3.

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.

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 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 spark plug including a center electrode; a metallic member forming a tubular shape around an axis of the spark plug, holding the center electrode therein, and having a hole formed in a side wall thereof and extending in a radial direction; and a ground electrode supported in the hole and extending from the hole toward the axis. The ground electrode has a fixing portion formed of metal and fixed to the hole, and an ignition portion containing a noble metal, disposed on a side toward the axis in relation to the fixing portion, and having a discharge surface for forming a gap between the ignition portion and the center electrode. The absolute value of the difference in coefficient of thermal expansion between the metallic member and the fixing portion is smaller than the absolute value of the difference in coefficient of thermal expansion between the metallic member and the ignition portion.

A spark plug including a center electrode; a metallic member forming a tubular shape around an axis of the spark plug, holding the center electrode therein, and having a hole formed in a side wall thereof and extending in a radial direction; and a ground electrode supported in the hole and extending from the hole toward the axis. The ground electrode has a fixing portion formed of metal and fixed to the hole, and an ignition portion containing a noble metal, disposed on a side toward the axis in relation to the fixing portion, and having a discharge surface for forming a gap between the ignition portion and the center electrode. The absolute value of the difference in coefficient of thermal expansion between the metallic member and the fixing portion is smaller than the absolute value of the difference in coefficient of thermal expansion between the metallic member and the ignition portion.