Abstract: A spark plug includes: a mounting bracket; a center electrode having a first end portion exposed and extended from first end portion of the mounting bracket; a slant-shape ground electrode that has first end side joined to the first end portion of the mounting bracket, has a surface of the second end side extended to be opposed to the first end portion of the center electrode, and has an extension direction inclined with respect to the center electrode; a convex portion protruding from a base material of the ground electrode on the surface thereof toward the center electrode, inclines toward the center electrode with respect to a protrusion direction, and has a convex portion opposed surface opposed to an end surface of the center electrode; and a precious metal layer formed on at least the convex portion opposed surface out of surfaces of the convex portion.

Abstract: A spark plug includes: a mounting bracket; a center electrode having a first end portion exposed and extended from first end portion of the mounting bracket; a slant-shape ground electrode that has first end side joined to the first end portion of the mounting bracket, has a surface of the second end side extended to be opposed to the first end portion of the center electrode, and has an extension direction inclined with respect to the center electrode; a convex portion protruding from a base material of the ground electrode on the surface thereof toward the center electrode, inclines toward the center electrode with respect to a protrusion direction, and has a convex portion opposed surface opposed to an end surface of the center electrode; and a precious metal layer formed on at least the convex portion opposed surface out of surfaces of the convex portion.

Abstract: A spark plug for an internal combustion engine is disclosed having a metal shell having an outer periphery formed with a mounting thread, a porcelain insulator fixedly secured to the metal shell on a central axis thereof, a center electrode retained within the porcelain insulator along a central axis thereof with a distal end located outside the porcelain insulator, and a ground electrode joined to the metal shell and having an end associated with the distal end of the center electrode to define therebetween a spark discharge gap. The ground electrode includes a facing surface intersecting the central axis of the center electrode and having a width equal to or less than 1.6 mm.

Abstract: A glow plug has a heating coil made of an alloy of iron, chromium and aluminum, a control coil made of nickel and serially connected with the heating coil, a heater case made of an inconel material and accommodating the coils therein, and a current line through which an electric current adjusted at a duty ratio changeable based on a voltage of the current according to a pulse width modulation control is supplied to the coils. The alloy of the heating coil and nickel of the control coil are superior in durability at high temperature. The inconel material of the case is superior in heat resisting property. In response to the current, resistance of the control coil is heightened, and the heating coil is heated to a maximum temperature to heat an air-fuel mixture of a combustion chamber of a diesel engine.

Abstract: A spark plug for an internal combustion engine is disclosed having a metal shell having an outer periphery formed with a mounting thread, a porcelain insulator fixedly secured to the metal shell on a central axis thereof, a center electrode retained within the porcelain insulator along a central axis thereof with a distal end located outside the porcelain insulator, and a ground electrode joined to the metal shell and having an end associated with the distal end of the center electrode to define therebetween a spark discharge gap. The ground electrode includes a facing surface intersecting the central axis of the center electrode and having a width equal to or less than 1.6 mm.

Abstract: According to the present invention, there is provided a spark plug for an internal combustion engine which includes a tubular metal shell, an insulator, a center electrode, and a ground electrode. In the spark plug, L1, which is the sum of lengths of an intermediate portion and a second outer shoulder of the insulator in the longitudinal direction of the insulator, is greater than or equal to 10 mm; the intermediate portion of the insulator has an outer surface that includes a first and a second section and has an electrically conductive coat only on the second section; and the first section of the outer surface of the intermediate portion of the insulator has a length in the longitudinal direction of the insulator in a range of 1 to 8 mm.

Abstract: A ground electrode has a proximal portion fixed to one end of a metallic housing and a distal portion extending toward one end of a center electrode so that an acute angle is formed between a center electrode axis and an axis of the distal portion of the ground electrode. A columnar ground electrode tip is fixed to a ground electrode end surface. The ground electrode tip protrudes from the ground electrode end surface and extends toward the center electrode along an axis crossing with an axis passing the ground electrode end surface. An axis of the center electrode tip is in a cross or skew relationship with an axis of the ground electrode tip.

Abstract: A ground electrode has a proximal portion fixed to one end of a metallic housing and a distal portion extending toward one end of a center electrode so that an acute angle is formed between a center electrode axis and an axis of the distal portion of the ground electrode. A columnar ground electrode tip is fixed to a ground electrode end surface. The ground electrode tip protrudes from the ground electrode end surface and extends toward the center electrode along an axis crossing with an axis passing the ground electrode end surface. An axis of the center electrode tip is in a cross or skew relationship with an axis of the ground electrode tip.