The invention relates to an apparatus for igniting a fuel mixture. Set apparatus comprises an ignition system for generating a high-voltage ignition voltage as well as a circuit device comprising a circuit for superimposing a high-frequency signal on to the high-voltage ignition voltage. The apparatus further comprises a spark plug in an engine block as well as a transmission element for transmitting the ignition voltage, onto which the high-frequency signal has been superimposed, to the spark plug. The transmission element includes a contact element which is provided with an electrically conductive coating along at least one portion of the longitudinal axis of the contact element, the impedance of the coding being lower than the impedance of the contact element.

A prechamber spark plug having a thermally enhanced prechamber cap with a thermally conductive core, such as one made from a copper-, aluminum- and/or silver-based material. Due to its location and function, a prechamber cap is exposed to thermal energy from a pre-combustion process taking place within a prechamber, as well as thermal energy from a combustion process taking place in a main combustion chamber. Thus, the prechamber cap is being heated on both its interior and its exterior and, if not sufficiently cooled, can become so hot that it undesirably triggers preignition events in the engine. The thermally enhanced prechamber cap may include a main body with an interior surface and an exterior surface, a thermally conductive core with one or more thermal segments and insert segments, and one or more openings extending between a prechamber and a main combustion chamber, where each opening extends through an insert segment that is designed to resistant to corrosion and/or erosion.

The invention relates to a spark plug connecting element, which includes a first contact element (9a) and a second contact element (9b), a resistor element (8) being situated between the first contact element (9a) and the second contact element (9b), the first contact element (9a) and the second contact element (9b) having a specific conductivity of 10.sup.2 S/m to 10.sup.8 S/m and the resistor element (8) having a specific conductivity of 10.sup.−3 S/m to 10.sup.1 S/m.

An ignition coil includes a coil main body portion, a conductive member, and a protective portion. The coil main body portion generates a high voltage. The conductive member electrically connects the coil main body portion and a terminal metal fitting of a spark plug. The conductive member is arranged inside the protective portion. The protective portion has an electrically insulating property. The conductive member includes an elastic portion that elastically deforms in a longitudinal direction of the conductive member, and a conductive terminal that is arranged on a distal end side of the elastic portion. The conductive terminal has a distal end surface that includes a concave surface or a convex surface that abuts on the terminal metal fitting of the spark plug. A contact portion between the concave surface or the convex surface and the terminal metal fitting of the spark plug has an annular shape.

An ignition coil includes a coil main body portion, a conductive member, and a protective portion. The coil main body portion generates a high voltage. The conductive member electrically connects the coil main body portion and a terminal metal fitting of a spark plug. The conductive member is arranged inside the protective portion. The protective portion has an electrically insulating property. The conductive member includes an elastic portion that elastically deforms in a longitudinal direction of the conductive member, and a conductive terminal that is arranged on a distal end side of the elastic portion. The conductive terminal has a distal end surface that includes a concave surface or a convex surface that abuts on the terminal metal fitting of the spark plug. A contact portion between the concave surface or the convex surface and the terminal metal fitting of the spark plug has an annular shape.

An apparatus for igniting a fuel mixture provides an ignition system for generating a high-voltage ignition voltage, a circuit device comprising a circuit for superimposing a high-frequency signal on to the high-voltage ignition voltage, a spark plug in an engine block, and a transmission element having a high-voltage conductor which is guided in an insulation element. The high-voltage conductor is used for transmitting the ignition voltage, onto which the high-frequency signal has been superimposed, to the spark plug. Further provided is an electrically conducting shielding element which surrounds the high-voltage conductor in an electromagnetically shielding manner at least along one portion of the longitudinal axis of the high-voltage conductor. The shielding element is connected in an electrically conducting manner to a ground potential of the circuit device and establishes a connection between the ground potential of the circuit device and a ground electrode of the spark plug.

A spark plug combustion ionization sensor for measuring ion current inside the cylinder of an internal combustion engine. The sensor measures ion current which flows when the energy released during combustion ionizes the air inside the cylinder, and thus can detect combustion and emission parameters. The spark plug combustion ionization sensor generally includes an insulated, dedicated sensing electrode, separate from the sparking electrode of a spark plug. The sensing electrode may also be shielded to further reduce interference such as electromagnetic interference (EMI). The use of a dedicated electrode allows for ion current measurement with less electromagnetic noise from the ignition process, and also eliminates the need for circuitry that is typically necessary when the sparking electrode is also used to sense ion current.

A spark plug combustion ionization sensor for measuring ion current inside the cylinder of an internal combustion engine. The sensor measures ion current which flows when the energy released during combustion ionizes the air inside the cylinder, and thus can detect combustion and emission parameters. The spark plug combustion ionization sensor generally includes an insulated, dedicated sensing electrode, separate from the sparking electrode of a spark plug. The sensing electrode may also be shielded to further reduce interference such as electromagnetic interference (EMI). The use of a dedicated electrode allows for ion current measurement with less electromagnetic noise from the ignition process, and also eliminates the need for circuitry that is typically necessary when the sparking electrode is also used to sense ion current.

In a method for manufacturing a spark plug, a space on a proximal end side of a center electrode in a shaft hole of an insulator is filled with first electrically conductive glass powder. A space on the proximal end side of the first electrically conductive glass powder in the shaft hole is filled with resistor composition powder. A space on the proximal end side of the resistor composition powder in the shaft hole is filled with second electrically conductive glass powder. The first electrically conductive glass powder, the resistor composition powder, and the second electrically conductive glass powder are sintered in the shaft hole. Prior to filling of the resistor composition powder, at least one of the insulator and the first electrically conductive glass powder is placed in an uncharged state, or the insulator and the first electrically conductive glass powder are placed in the same charged state.

In a method for manufacturing a spark plug, a space on a proximal end side of a center electrode in a shaft hole of an insulator is filled with first electrically conductive glass powder. A space on the proximal end side of the first electrically conductive glass powder in the shaft hole is filled with resistor composition powder. A space on the proximal end side of the resistor composition powder in the shaft hole is filled with second electrically conductive glass powder. The first electrically conductive glass powder, the resistor composition powder, and the second electrically conductive glass powder are sintered in the shaft hole. Prior to filling of the resistor composition powder, at least one of the insulator and the first electrically conductive glass powder is placed in an uncharged state, or the insulator and the first electrically conductive glass powder are placed in the same charged state.