One example provides a spark plug having a center electrode including a first material and a second material, the second material having a hardness rating greater than a hardness rating of the first material. The center electrode includes an electrode head, wherein at least a portion of the electrode head is disposed beyond an end surface of an insulative nose toward the firing end and has a cross-sectional area perpendicular to an axial centerline greater than a cross-sectional area of the end surface of the insulative nose. The center electrode has a region of first material disposed axially beyond the end surface of the insulative nose, and includes a shield element of the second material which covers exposed surfaces of the region of first material disposed beyond the end surface of the insulative nose. An electrode wire extends from the electrode head into a central bore of the insulative nose.

One example provides a spark plug having a center electrode including a first material and a second material, the second material having a hardness rating greater than a hardness rating of the first material. The center electrode includes an electrode head, wherein at least a portion of the electrode head is disposed beyond an end surface of an insulative nose toward the firing end and has a cross-sectional area perpendicular to an axial centerline greater than a cross-sectional area of the end surface of the insulative nose. The center electrode has a region of first material disposed axially beyond the end surface of the insulative nose, and includes a shield element of the second material which covers exposed surfaces of the region of first material disposed beyond the end surface of the insulative nose. An electrode wire extends from the electrode head into a central bore of the insulative nose.

A spark plug may include a center electrode disposed in a center portion of the spark plug, an insulator surrounding the center electrode, and a metal shell surrounding the insulator and having a ground electrode extending downwards from a lower end of the metal shell and an inner surface facing the insulator, the inner surface being concavely shaped to form a shielding space between the concavely shaped portion of the inner surface and the insulator for adjusting a heat range of the spark plug.

A spark plug may include a center electrode disposed in a center portion of the spark plug, an insulator surrounding the center electrode, and a metal shell surrounding the insulator and having a ground electrode extending downwards from a lower end of the metal shell and an inner surface facing the insulator, the inner surface being concavely shaped to form a shielding space between the concavely shaped portion of the inner surface and the insulator for adjusting a heat range of the spark plug.

Disclosed is a spark plug capable of suppressing high-frequency noise by improving the material of an electrical connection part between a center electrode and a metal terminal within an axial hole of an insulator. A spark plug has an electrical connection part arranged in an axial hole of an insulator to establish electrical connection between a center electrode and a metal terminal. The electrical connection part includes a conductor having a first crystal phase formed of a Fe-containing oxide and a second crystal phase formed of a conductive metal oxide of perovskite crystal structure.

Disclosed is a spark plug capable of suppressing high-frequency noise by improving the material of an electrical connection part between a center electrode and a metal terminal within an axial hole of an insulator. A spark plug has an electrical connection part arranged in an axial hole of an insulator to establish electrical connection between a center electrode and a metal terminal. The electrical connection part includes a conductor having a first crystal phase formed of a Fe-containing oxide and a second crystal phase formed of a conductive metal oxide of perovskite crystal structure.

An electrically conductive cover which in assembly is received over at least part of a spark plug boot and at least part of a nut portion of a metal body of a spark plug received in the boot. The cover may have an opening through which an arm portion of the boot extends which arm portion receives an electric wire for supplying a current at a high potential voltage to the spark plug.

An electrically conductive cover which in assembly is received over at least part of a spark plug boot and at least part of a nut portion of a metal body of a spark plug received in the boot. The cover may have an opening through which an arm portion of the boot extends which arm portion receives an electric wire for supplying a current at a high potential voltage to the spark plug.

A spark plug RFI suppression arrangement comprises a spark plug having a proximal end at which an ignition terminal is located and a distal end at which a pair of electrodes are separated by a spark gap. The spark plug further has an insulator portion and a conductive case located intermediate the proximal and distal ends. The arrangement further has an ignition wire having an end portion carrying a connector removably attached to the ignition terminal of the spark plug. A spark plug boot is located at the end portion of the ignition wire, the boot being configured to cover the connector and at least a portion of the spark plug. A radio frequency interference (RFI) suppression sleeve is connected to the spark plug boot and is in electrical communication with the conductive case of the spark plug such that interference produced by operation of the spark plug is suppressed by grounding through the conductive case.

A spark plug RFI suppression arrangement comprises a spark plug having a proximal end at which an ignition terminal is located and a distal end at which a pair of electrodes are separated by a spark gap. The spark plug further has an insulator portion and a conductive case located intermediate the proximal and distal ends. The arrangement further has an ignition wire having an end portion carrying a connector removably attached to the ignition terminal of the spark plug. A spark plug boot is located at the end portion of the ignition wire, the boot being configured to cover the connector and at least a portion of the spark plug. A radio frequency interference (RFI) suppression sleeve is connected to the spark plug boot and is in electrical communication with the conductive case of the spark plug such that interference produced by operation of the spark plug is suppressed by grounding through the conductive case.