Ngk Spark Plug Company, Limited

Mitsubishi Materials Corporation

Kei Takahashi

Yukinobu Hasegawa

Atsushi Komura

Kazuhiko Mori

Hironobu Mizutani

Toshiyuki Taniuchi

Tomoaki Shindo

Hiroaki Takashima

Masafumi Fukumura

Tatsunori Yamada

Yasushi Sakakura

Daisuke Kasahara

Koji Okazaki

Yusuke Fuji

Tomoyuki Igarashi

Masaki Tokumaru

A spark plug includes: a central electrode extending from a front end side to a rear end side along an axis; an insulator including a front end section formed to be a bottomed tube surrounding a tip of the central electrode; a metal shell shaped to be tubular and structured to support the insulator such that the front end section of the insulator projects to the front end side from a front end section of the metal shell; and a plurality of ground electrodes each of which includes a first end forming a discharge gap with the front end section of the insulator and includes a second end connected to the front end section of the metal shell. The plurality of ground electrodes include a pair of ground electrodes different from each other in size of their discharge gaps.

Spark plug having a plurality of ground electrodes

A spark plug includes a central electrode and a noble metal tip, which are joined together with a fusion portion interposed therebetween. A tip-adjoining boundary of the fusion portion has a shape that curves convexly toward the fusion portion. A central-electrode-adjoining boundary of the fusion portion has a shape that curves convexly toward the central electrode. The outline of a portion of the fusion portion exposed to the outer surface has a shape that curves concavely into the inner side of the fusion portion.

Spark plug

A spark plug includes: a metallic shell having a through hole extending in a direction of an axis; a cap covering an opening in the metallic shell; a melt portion formed between the cap and the metallic shell to join the cap and the metallic shell to each other; and a gap extending from a specific space which is surrounded by the metallic shell and the cap to the melt portion and interposed between the metallic shell and the cap.

Spark plug and method for manufacturing spark plug

A spark plug includes: an insulator having an axial hole; a conductive member disposed around the insulator; a center electrode disposed inside the axial hole, having a bar shape extending in the axial direction, and located on a rear end side with respect to a front end of the conductive member; a ground electrode forming a spark gap between the ground electrode and the center electrode; and a connection part including a plurality of spokes extending in a radial direction whose inner ends are connected to the ground electrode, and connecting the conductive member to the ground electrode. The connection part includes a joint part that is jointed to an inner surface of the conductive member, and the ground electrode has at least one of a notch and a groove at a position that is different from a position connected to the spokes in a circumferential direction.

A spark plug includes a center electrode, a ground electrode, and a cylindrical metal shell. The ground electrode is welded to the metal shell via a weld portion. The weld portion is formed along the outer circumference end part of an annular part in the ground electrode. The weld portion has a plurality of melt extending parts extending toward the inner circumference side from the outer circumference end part of the annular part and aligned such that adjacent ones are connected to each other at the end part. The plurality of melt extending parts partially include smaller melt extending parts whose melting depth is smaller than others.

Spark plug and manufacturing method thereof

An ignition plug having a center electrode, a grounding electrode, an insulator, and a metal shell. The center electrode is held by the insulator, and the insulator is held by metal shell. A cavity is formed between the grounding electrode and the center electrode. The grounding electrode is joined to the inner wall surface of the metal shell via a melting portion. In the melting portion, in a predetermined cutting surface MS including a melting deepest point DP and a central axis CX, a percentage ratio MDD of a melting depth MD of the melting portion with respect to a thickness of the grounding electrode is 5% or more, and an area Sm of a portion included in an outer circumferential side of the metal shell is 10% or more of the entire area S.

A spark plug includes a tip joined to a center electrode. The coefficient of linear thermal expansion of the center electrode is greater than that of the tip. The tip has a gap-forming portion having a maximum width of 1.2 mm or greater and forming a gap in cooperation with the ground electrode and a to-be-joined portion joined to the center electrode. At a position A which is shifted 0.1 mm from the forward end of the outer surface of the fusion portion toward the forward end side, the width of the to-be-joined portion measured on the cross section is smaller than the width of the gap-forming portion. The to-be-joined portion satisfies Dtw/Dw&#x2266;1.1, where Dtw represents the width of the to-be-joined portion at the position A, and Dw represents the width of the fusion portion at the forward end of the outer surface thereof.

Spark plug having center electrode tip of varying widths

A cermet insert having a structure composed of a hard phase and a binding phase and, as a sintered body composition, containing Ti, Nb and/or Ta, and W in a total amount of Ti in terms of carbonitride, Nb and/or Ta in terms of carbide and W in terms of carbide of 70 to 95 wt. % of an entirety of the microstructure, and containing W in terms of carbide in an amount of 15 to 35 wt. % of the entirety of the microstructure, the sintered body composition further containing Co and/or Ni. The hard phase has one or two or more of the phases: (1) a first hard phase of a core-having structure whose core portion contains a titanium carbonitride phase and a peripheral portion containing a (Ti, W, Ta/Nb)CN phase, (2) a second hard phase of a core-having structure whose core portion and peripheral portion both contain a (Ti, W, Ta/Nb)CN phase, and (3) a third hard phase of single-phase structure including a titanium cabonitride phase. Moreover, the titanium carbonitride phase includes a W-rich phase unevenly distributed in the titanium carbonitride phase.

Cermet insert and cutting tool

One aspect of this titanium carbonitride-based cermet insert has a microstructure including 75 to 90 area % of a hard phase and the balance as a binding phase, wherein the hard phase includes a first hard phase in which a core-having structure includes a TiCN phase and a peripheral portion includes a (Ti,W,Ta/Nb)CN phase, a second hard phase including a (Ti,W,Ta/Nb)CN phase, and a third hard phase including a TiCN phase, and the binding phase contains 18 to 33% of Co, 20 to 35% of Ni, 5% or less of Ti and Ta and/or Nb, and 40 to 60 mass % of W. In another aspect of this cermet insert, a total of an amount of Ti converted as carbonitride, an amount of Ta and/or Nb converted as carbide, and an amount of W converted as carbide is 70 to 95 mass %, an amount of W converted as carbide is 20 to 35 mass %, and Co and Ni are 5 to 30 mass %, this cermet insert has a microstructure including a hard phase containing (Ti,W,Ta/Nb)CN and a binding phase containing, as main components thereof, W and Co and/or Ni, and 40 to 65 mass % of the W is contained in the hard phase. This cutting tool includes a holder and the cermet insert described above held and fixed by the holder.

Growing community of inventors

Nagoya, Japan

Kei Takahashi