摘要:
A precious metal tip on the side of a ground electrode is indirectly joined to the front end portion of the ground electrode via a mounting part interposed therebetween. The mounting part includes a base part and a protruding part. First, in the state where the precious metal tip is in contact with the protruding part, laser welding or the like is performed thereon to form a fused part and obtain a complex, and the base part is joined to a flat surface of the ground electrode by resistance welding. The grain size of grains of the mounting part in the vicinity of the of the fused part is greater than the grain size of the grain size of the grains thereof in the vicinity of the ground electrode, and the grain size of the grains of the flange part of the mounting part is smaller than the grain size of the grains of the protruding part.
摘要:
A spark plug includes a cylindrical metal shell; a cylindrical insulator that is held in the metal shell; a center electrode; and a ground electrode that comprises a ground electrode main body part and a noble metal tip, a spark discharge gap being formed between the leading end of the center electrode and the noble metal tip wherein at least a portion of the ground electrode main body part, to which the noble metal tip is joined, is made of Ni alloy containing 12 to 35 mass % of Cr, 7 mass % or less of Fe, 0.5 to 5 mass % of Al, 0.3 to 5 mass % of Si and 50 mass % or more of the balance, and wherein the joined portion and the noble metal tip are joined by laser welding or electron beam welding.
摘要:
A spark plug having a center electrode and a ground electrode including a ground electrode main body part having an end thereof facing the center electrode and a noble metal tip joined to the ground electrode main body part at a position facing a leading end of the center electrode, a spark discharge gap being formed between the leading end of the center electrode and the noble metal tip, wherein at least a portion of the ground electrode main body part, to which the noble metal tip is joined, is made of an Ni alloy containing 12 to 45 mass % of Cr, 7 mass % or less of Fe, 0.5 to 5 mass % of Al, 0.3 to 5 mass % of Si and 50 mass % or more of the balance, and wherein the joined portion and the noble metal tip are joined by laser welding or electron beam welding.
摘要:
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. The grain size of the grains of the mounting part 51 in the vicinity of the fused part 42 is smaller than the grain size of the grains thereof in the vicinity of the ground electrode 27, and the grain size of the grains of the flange part 52 of the mounting part 51 is smaller than the grain size of the grains of the protruding part 54.
摘要:
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).
摘要:
The present invention provides a spark plug which is capable of suppressing a occurrence of crack and separation by determining a structural configuration of a melting portion formed in a junction portion between a discharge portion and a pedestal portion which form an ignition portion that protrudes from a ground electrode. In a profile line shape of a cross section including a center axis P of an ignition portion 80, an exposure surface 88 of a melting portion 83 connects a side surface 82 of a discharge portion 81 and a side surface 85 of a pedestal portion 84. Further, an exterior angle θ formed between an imaginary line Q, which passes through a boundary position X1 between the melting portion 83 and the pedestal portion 84 and a boundary position X2 between the melting portion 83 and the discharge portion 81, and the center axis P at a node C, satisfies 135°≦θ≦175°. Furthermore, a proportion T/S of a forming depth T of the melting portion 83 to an outside diameter S of the discharge portion 81 satisfies T/S≧0.5.
摘要:
The present invention provides a spark plug which is capable of suppressing a occurrence of crack and separation by determining a structural configuration of a melting portion formed in a junction portion between a discharge portion and a pedestal portion which form an ignition portion that protrudes from a ground electrode. In a profile line shape of a cross section including a center axis P of an ignition portion 80, an exposure surface 88 of a melting portion 83 connects a side surface 82 of a discharge portion 81 and a side surface 85 of a pedestal portion 84. Further, an exterior angle θ formed between an imaginary line Q, which passes through a boundary position X1 between the melting portion 83 and the pedestal portion 84 and a boundary position X2 between the melting portion 83 and the discharge portion 81, and the center axis P at a node C, satisfies 135°≦θ≦175°. Furthermore, a proportion T/S of a forming depth T of the melting portion 83 to an outside diameter S of the discharge portion 81 satisfies T/S≧0.5.
摘要:
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).
摘要:
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.
摘要:
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.