摘要:
A spark plug 1 includes an insulator 2, a metal shell 3, a center electrode 5 and a ground electrode 27. A spark discharge gap 33 is formed between a front end portion 28 of the center electrode 5 and the ground electrode 27. The metal shell 3 has a through hole 29 therein and a metal convex portion 21 inwardly radially projecting in the through hole 29. The metal convex portion 21 includes a convex rearward face 30, a convex inner circumferential face 31 and a convex forward face 32. The through hole 29 has an inner diameter A (mm) at a front end side inner circumferential face 40, which is located at the front end side with respect to the convex forward face 32. The insulator 2 is inserted in the through hole 29 and has a first insulator taper portion 14, a second insulator taper portion 36 and a base 37 between the taper portions. The present invention satisfies the following representations: G≦(A−B)/2; A≧7.3; and 2≦XX≦4, where “B” (mm) is an outer diameter of a border K between an insulator front end portion 38 and the second insulator taper portion 36, where “G” (mm) is a distance of a spark discharge gap 33, and where “XX” (mm) is a length from a very-end portion FF of the convex inner circumferential face 31 to the border K in the axial C1 direction.
摘要:
A spark plug 1 includes an insulator 2, a metal shell 3, a center electrode 5 and a ground electrode 27. A spark discharge gap 33 is formed between a front end portion 28 of the center electrode 5 and the ground electrode 27. The metal shell 3 has a through hole 29 therein and a metal convex portion 21 inwardly radially projecting in the through hole 29. The metal convex portion 21 includes a convex rearward face 30, a convex inner circumferential face 31 and a convex forward face 32. The through hole 29 has an inner diameter A (mm) at a front end side inner circumferential face 40, which is located at the front end side with respect to the convex forward face 32. The insulator 2 is inserted in the through hole 29 and has a first insulator taper portion 14, a second insulator taper portion 36 and a base 37 between the taper portions. The present invention satisfies the following representations: G≦(A−B)/2; A≧7.3; and 2≦XX≦4, where “B” (mm) is an outer diameter of a border K between an insulator front end portion 38 and the second insulator taper portion 36, where “G” (mm) is a distance of a spark discharge gap 33, and where “XX” (mm) is a length from a very-end portion FF of the convex inner circumferential face 31 to the border K in the axial C1 direction.
摘要:
A spark plug for an internal combustion engine capable of ensuring sufficient gastightness of a combustion chamber and meeting demand for a reduction in diameter.
摘要:
A spark plug includes an insulator having an axial hole extending in the direction of an axis, and a terminal electrode disposed at a rear end portion of the axial hole. An identifier bearing externally visible identification information is joined to the rear end surface of the terminal electrode. The identifier has a thickness of 0.03 mm or greater along the direction of the axis.
摘要:
A spark plug having an insulator with improved breakage resistance. The spark plug has a cross-section that satisfies the following relationship: 0.6 mm
摘要:
A spark plug for an internal combustion engine capable of ensuring sufficient gastightness of a combustion chamber and meeting demand for a reduction in diameter.
摘要:
A spark plug having an insulator with improved breakage resistance. The spark plug has a cross-section that satisfies the following relationship: 0.6 mm
摘要:
A spark plug having a center electrode 2 formed from an electrode base material 2n, which is made of an Ni alloy containing an alloy component (e.g., Cr) capable of forming an oxide semiconductor having a resistivity of negative temperature coefficient. Thus, a corrosion suppression layer originating from the components of the electrode base material is formed on the surface of a tip end portion of the insulator 3, so that corrosion (channeling) of the surface of the tip end portion of the insulator 3 due to creeping spark discharge can be effectively suppressed. In addition, when the constituent metal of the electrode base material 2n has a coefficient of thermal conductivity of 17 to 30 W/m·K, the heat transfer performance of the electrode is enhanced, so that durability against electrode consumption can be greatly improved.
摘要:
A spark plug including a center electrode and a ground electrode. A center electrode noble metal tip is joined to a leading end portion of a center electrode, and a ground electrode noble metal tip is joined to a center-electrode-side side surface of the ground electrode. A distal end portion of the ground electrode noble metal tip protrudes from a distal-end surface of the ground electrode by 0.1 mm to 1.5 mm. A center-electrode-side side surface of the ground electrode noble metal tip projects from a center-electrode-side side surface by 0.15 mm to 0.6 mm. The ground electrode includes chamfered portions. Thickness lengths and widthwise lengths of the respective chamfered portions achieved within a cross section perpendicular to a center axis of the ground electrode are set to 0.2 mm or more.
摘要:
There is provided a spark plug wherein an insulator and a metallic shell, when observed in a section made by a plane including an axis of a spark plug, have therebetween a gap of less than 0.45 mm at a more front end side than an engagement position of a packing and a first insulator stepped portion, and the gap is provided axially from a most front end side engagement position of the packing and a first insulator stepped portion as a starting point to a finishing point that is apart from the starting point by 1.2 mm or more toward the front end side while being apart from a front end surface of the metallic shell by 7.9 mm or more toward a rear end side.