Abstract: A method of producing a cylindrical insulator for a spark plug includes a molding step of forming ceramic powder filled in a cavity defined by a mold and a molding pin into a compact. In a first removal step of removing the compact from the mold, the compact has at least one protrusion formed in at least one recess of the molding pin formed in an outer cylindrical surface of the molding pin, and the at least one protrusion is locked in the at least one recess, thereby allowing the compact to be removed with the molding pin from the mold. In a second removal step of removing the molding pin from the compact, the molding pin is turned or rotated in the circumferential direction about the compact, causing the at least one recess to cut the at least one protrusion from the compact, and thereafter the molding pin is removed from the compact.

Abstract: In a spark plug, a noble metal tip includes an Ir-alloy material and has a circular-columnar shape that has a predetermined outer diameter and is formed by the Ir-alloy material being stretched. The spark plug generates discharge between the noble metal tip and a ground electrode that is arranged to oppose an outer peripheral surface of the noble metal tip. The Ir-alloy material includes crystal grains of an Ir alloy having an average aspect ratio that is adjusted to be equal to or greater than 1.3 and equal to or less than 4.8. The average aspect ratio is an average value of aspect ratios of the crystal grains each being a value obtained by a length of the respective crystal grains in an axial direction of the noble metal tip being divided by a length of the respective crystal grains in a direction perpendicular to the axial direction.

Abstract: A spark plug has a housing of a cylindrical shape and an insulator supported to an inside of the housing. A channel part is formed at a distal end side of the housing. The channel part is open so that the inside of the housing communicates with an outside of the housing through the channel part. The channel part has a channel bottom having a tapered shape oblique relative to a plug central axis. An overall channel bottom is arranged in the housing closer to a proximal end side than to the distal end side of the housing.

Abstract: In a spark plug, a noble metal tip includes an Ir-alloy material and has a circular-columnar shape that has a predetermined outer diameter and is formed by the Ir-alloy material being stretched. The spark plug generates discharge between the noble metal tip and a ground electrode that is arranged to oppose an outer peripheral surface of the noble metal tip. The Ir-alloy material includes crystal grains of an Ir alloy having an average aspect ratio that is adjusted to be equal to or greater than 1.3 and equal to or less than 4.8. The average aspect ratio is an average value of aspect ratios of the crystal grains each being a value obtained by a length of the respective crystal grains in an axial direction of the noble metal tip being divided by a length of the respective crystal grains in a direction perpendicular to the axial direction.

Abstract: A spark plug has a housing, an insulator, a central electrode and a ground electrode. A projection part is formed projecting radially from the housing. The spark plug has a structure which satisfies a relationship of t2/t1?0.85, s1?0.5, and s1?1.05?t2/t1. A leg part of the insulator has a first end and a second end in an axial direction thereof. The second end is located opposite to the first end in the axial direction. In the relationship, t1 represents a first radial thickness of the first end in a radial direction of the leg part, t2 represents a center radial thickness in the radial direction at a middle position of the leg part, and s1 represents a first gap width in the radial direction of the housing between the projection part of the housing and the first end of the leg part.

Abstract: A spark plug has a housing, an insulator, a central electrode and a ground electrode. A projection part is formed projecting radially from the housing. The spark plug has a structure which satisfies a relationship of t2/t1?0.85, s1?0.5, and s1?1.05?t2/t1. A leg part of the insulator has a first end and a second end in an axial direction thereof. The second end is located opposite to the first end in the axial direction. In the relationship, t1 represents a first radial thickness of the first end in a radial direction of the leg part, t2 represents a center radial thickness in the radial direction at a middle position of the leg part, and s1 represents a first gap width in the radial direction of the housing between the projection part of the housing and the first end of the leg part.

Abstract: A spark plug electrode is provided, in which an electrode member in which a total of 0.3 to 7.5 wt % of at least one of Ta and Nb is added to an IrRh alloy is provided at a discharge part.

Abstract: A spark plug has a housing, an insulator, a central electrode and a ground electrode. At least one projection part is formed on an outer peripheral surface of the insulator at a location facing a distal end cylindrical surface of the insulator in a radial direction of the spark plug so that at least one projection part has a minimum distance measured from a plug central axis of the spark plug, which is longer than a distance of another part of the insulator measured from the plug central axis. On a cross section of the spark plug, at least one projection part is formed on the outer peripheral surface of the insulator in a direction between at least one projection part and the plug central axis which crosses to a direction between a rod-shaped part and the plug central axis.

Abstract: A spark plug includes a ground electrode facing a distal end surface of a center electrode. In a main body of the ground electrode, a first slanted surface is formed at a portion on a side facing the distal end surface and upstream of the center electrode relative to the airflow, a facing portion, a second slanted surface is formed at a portion on a side opposite to the side facing the distal end surface and upstream of the center electrode relative to the airflow, and when T represents a thickness of the main body of the ground electrode and Su represents a distance from a connection between the first slanted surface and the second slanted surface to the facing portion, 2T/16?Su?8T/16.

Abstract: A method of producing a cylindrical insulator for a spark plug includes a molding step of forming ceramic powder filled in a cavity defined by a mold and a molding pin into a compact. In a first removal step of removing the compact from the mold, the compact has at least one protrusion formed in at least one recess of the molding pin formed in an outer cylindrical surface of the molding pin, and the at least one protrusion is locked in the at least one recess, thereby allowing the compact to be removed with the molding pin from the mold. In a second removal step of removing the molding pin from the compact, the molding pin is turned or rotated in the circumferential direction about the compact, causing the at least one recess to cut the at least one protrusion from the compact, and thereafter the molding pin is removed from the compact.

Abstract: A spark plug has a housing of a cylindrical shape and an insulator supported to an inside of the housing. A channel part is formed at a distal end side of the housing. The channel part is open so that the inside of the housing communicates with an outside of the housing through the channel part. The channel part has a channel bottom having a tapered shape oblique relative to a plug central axis. An overall channel bottom is arranged in the housing closer to a proximal end side than to the distal end side of the housing.

Abstract: A spark plug has a housing, an insulator, a central electrode and a ground electrode. At least one projection part is formed on an outer peripheral surface of the insulator at a location facing a distal end cylindrical surface of the insulator in a radial direction of the spark plug so that at least one projection part has a minimum distance measured from a plug central axis of the spark plug, which is longer than a distance of another part of the insulator measured from the plug central axis. On a cross section of the spark plug, at least one projection part is formed on the outer peripheral surface of the insulator in a direction between at least one projection part and the plug central axis which crosses to a direction between a rod-shaped part and the plug central axis.

Abstract: On a base part forming a ground electrode in a spark plug, a facing surface is formed facing a distal end surface of a central electrode to have a shortest gap between the facing surface and the central electrode. A first slope surface is formed on an upper surface of the base part. A downstream-side end surface is formed parallel with a virtual plane, and connected to the first slope surface. A second slope surface is formed on a lower surface of the base part, connected to a downstream-side end surface. An opposing surface is formed on the lower surface of the base part. A width of the facing surface is wider than a width of the opposing surface. A first angle of the facing surface to the first slope surface satisfies a relationship of 10°??1?40°.

Abstract: On a base part forming a ground electrode in a spark plug, a facing surface is formed facing a distal end surface of a central electrode to have a shortest gap between the facing surface and the central electrode. A first slope surface is formed on an upper surface of the base part. A downstream-side end surface is formed parallel with a virtual plane, and connected to the first slope surface. A second slope surface is formed on a lower surface of the base part, connected to a downstream-side end surface. An opposing surface is formed on the lower surface of the base part. A width of the facing surface is wider than a width of the opposing surface. A first angle of the facing surface to the first slope surface satisfies a relationship of 10°??1?40°.

Abstract: A spark plug includes a ground electrode facing a distal end surface of a center electrode. In a main body of the ground electrode, a first slanted surface is formed at a portion on a side facing the distal end surface and upstream of the center electrode relative to the airflow, a facing portion, a second slanted surface is formed at a portion on a side opposite to the side facing the distal end surface and upstream of the center electrode relative to the airflow, and when T represents a thickness of the main body of the ground electrode and Su represents a distance from a connection between the first slanted surface and the second slanted surface to the facing portion, 2T/16?Su?8T/16.

Abstract: A spark plug electrode is provided, in which an electrode member in which a total of 0.3 to 7.5 wt % of at least one of Ta and Nb is added to an IrRh alloy is provided at a discharge part.

Abstract: In a spark plug for an internal combustion engine, an insulator is held inside a housing such that a proximal end thereof projects in an axial direction. A center electrode is held inside the insulator such that a distal end thereof projects. A terminal fitting is connected to the proximal end of the insulator and provided such that electricity is conducted between the center electrode and the terminal fitting. A ground electrode forms a spark discharge gap between the distal end of the center electrode and the ground electrode. A first gap is formed between the proximal end of the insulator and the terminal fitting, a second gap is formed between a proximal end of the housing and the insulator, and at least one of the first gap and the second gap is filled with a filler.

Abstract: A center electrode is held in insulating glass, in which a tip end portion of the center electrode protrudes. A ground electrode has a connection part connected to a housing. The ground electrode forms a spark discharge gap between the center electrode and the ground electrode. The ground electrode has a ground base material that includes the connection part and a ground protrusion part that protrudes from the ground base material toward the center electrode and forms the spark discharge gap between the center electrode and the ground electrode. An angle between a ground discharge surface of the ground protrusion part and a side surface of the ground protrusion part is a right angle or an acute angle. At least a portion of the side surface of the ground protrusion part and at least a portion of a side surface of the ground base material are flush with each other.

Abstract: A spark plug has a spark plug housing of a cylindrical shape, an insulator of a cylindrical shape, a central electrode, a ground electrode and a terminal metal fitting. The insulator has a head part projecting toward a distal end side of the spark plug from the spark plug housing. The central electrode and the ground electrode forms a discharge gap. The terminal metal fitting, electrically connected to the central electrode, has a main body part and an exposed part. The exposed part of the terminal metal fitting has a head part. An outer diameter of the head part of the exposed part is greater than an outer diameter of the main body part. A ratio Dt/Di of not less than 0.8 is satisfied, Di represents an outer diameter of the head part of the insulator and Dt represents an outer diameter of the head part of the exposed part.

Abstract: An ignition plug includes a main metal fitting; an earth electrode having one end fixed to the main metal fitting and including, in a part of the other end, an inclined portion inclined toward the center axis line of the main metal fitting; an earth electrode-side chip joined to the inclined portion; and a center electrode having one end exposed from the main metal fitting. The ignition plug includes: a pedestal which has an elliptic cylindrical shape, is disposed so as to have a minor axis directed toward the earth electrode-side chip, and has an end surface forming an inclined surface inclined along the minor axis with respect to the center axis line; and a center electrode-side chip laser-welded to the inclined surface. The earth electrode-side chip and the center electrode-side chip face each other.