Abstract: A spark member (70) is formed by joining a noble metal member (71) and an intermediate member (75) and is provided in a spark discharge gap between a center electrode and a ground electrode (30). A bottom surface (80) of the intermediate member (75) is resistance-welded to an inner surface (33) of the ground electrode (30), and a weld metal zone (73) is formed in the region of joint therebetween. As viewed on the section of the spark member (70) which contains a centerline (Q), the weld metal zone (73) is reliably formed within the range of the length (D) of a columnar portion (76) as measured along a direction orthogonal to the projecting direction of the spark member (70) and has a length (d) of at least 0.1 times (10% of) the length (D).

Abstract: A spark plug in which an ignition portion of a ground electrode formed through joining of a noble metal chip to the ground electrode has high durability, and a method of manufacturing the spark plug.

Abstract: There is provided a spark section (80) of needle-like shape protruding from an inner surface (33) of a ground electrode (30) to define a spark gap between the spark section and an electrode tip on a center electrode. The spark section (80) has a noble metal member (81) and an intermediate member (86) joined to each other. The materials of the noble metal member (81) and the intermediate member (86) are selected in such a manner that the thermal conductivity of the intermediate member (86) is lower than that of the noble metal member (81). This limits heat radiation through the heat radiation passage from the noble metal member (81) through the intermediate member (86) to the ground electrode (30) so as to maintain the noble metal member (81) at a higher temperature than conventional types and reduce a quenching effect of the noble metal member (81) on a flame core generated in the spark gap for improvement in ignition performance.

Abstract: A spark plug in which an ignition portion of a ground electrode formed through joining of a noble metal chip to the ground electrode has high durability, and a method of manufacturing the spark plug.

Abstract: An ignition part (80) of a ground electrode (30) includes a fused part (85) in which construction materials of a base portion (82) and a noble metal member (81) are fused and mixed by performing laser welding on the two. In the fused part (85), an average ratio P of components originated from the noble metal member (81) at points K1, L1, and M1 is equal to or greater than 80%, and an average ratio Q of components originated from the base portion at points K3, L3, and M3 is equal to or higher than 20%, and P+Q is equal to or higher than 160%. Accordingly, it is possible to obtain joining strength in the parts in the ignition part (80), thereby sufficiently preventing the generation of cracks, separation, and the like due to thermal stress.

Abstract: In a spark plug having a precious metal tip joined to the front end portion of a ground electrode, the stable junction state of the precious metal tip is guaranteed for a long time. A precious metal tip 32 on the side of a ground electrode 27 is not directly joined to the front end portion of the ground electrode 27 but indirectly joined with a mounting part 51 interposed therebetween. The mounting part 51 includes a base part 53 which has a disc shape and is provided with a flange part 52 on its outer periphery and a protruding part 54 which protrudes from the base part 53 and has a columnar shape. First, in the state where the precious metal tip 32 is in contact with the protruding part 54 of the mounting part 51, laser welding or the like is performed thereon to form a fused part 42 and obtain a complex, and the base part 53 of the mounting part 51 is joined to a flat surface of the ground electrode 27 by resistance welding.

Abstract: A gasket for use around a thread neck of an automotive component, the gasket dimensioned to prevent the gasket from falling off of the thread neck and to prevent a male screw portion from biting into the gasket.

Abstract: 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.

Abstract: In a creeping discharge type spark plug, the firing surface forming portions of a center electrode and a ground electrode are made of a metallic material containing a corrosion impeding component consisting of one or more of Fe, Cr and Cu. The spark plug is attached to an internal combustion engine. When it is operated under conditions of a predetermined high speed and high load, a corrosion impeding layer containing a corrosion impeding component is formed on the surface of the top end of an insulating member, with progression of spark discharge in spark discharge gaps. The corrosion impeding layer thus formed protects the center electrode from the attack by the creeping discharge spark. Therefore, the channeling is considerably effectively prevented or restricted.

Abstract: 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.