Ngk Spark Plug Company, Limited

Shinya Murakoshi

Takaya Yoshikawa

Hiroyuki Suzuki

Hirofumi Okada

Shinsuke Ito

Kazuto Morita

Nobutuki Hotta

A configuration in which fixing is performed by inserting a rear end of a lead shaft member into an attachment hole of an external terminal at the rear of a glow plug and crimping an outer peripheral face of the external terminal. The outer peripheral face of a crimp formation region () of the external terminal () having a polygonal cross section is formed into a crimped portion () provided by round crimping toward a circle, and the external terminal () is fixed to the rear end () of the lead shaft member (). Due to the configuration obtained from the round crimping of the polygon, plating breaks and the like are not easily produced in the plating layer on the surface of the external terminal.

Glow plug and method of manufacturing the same

An object is to provide a glow plug in which a gap can be prevented from being generated between a ceramic heater and a cylindrical member even at the time of use in an internal combustion engine, etc. so that electrical conduction of the glow plug can be prevented from being lowered. A glow plug includes: a rod-shaped ceramic heater; a rod-shaped center poleextending axially so as to electrically connect to the outside; and a cylindrical memberhaving a front end portionbonded to an outer circumferential surfaceof a rear end side of the ceramic heater, and a rear end portionbonded to an outer circumferential surface of a front end side of the center pole, the cylindrical memberbeing made by a metal material for electrically connecting one of a pair of lead portions and the center poleto each other, the glow plug characterized in that the cylindrical memberhas a Vickers hardness of not lower than 200 HV at 25&#xb0; C.

Glow plug

A glow plug comprising: a ceramic heater which houses a heating element defined herein in a tip end side of said ceramic heater, and which elongates in an axial direction; a cylindrical metal shell which has a shaft hole, which houses a rear end portion of said ceramic heater in said shaft hole, and which holds said ceramic heater in said shaft hole directly or via another member; and a center pole including a center-pole rear end portion as defined herein and a center-pole tip end portion as defined herein, said ceramic heater being mechanically rigidly joined to said heater connecting portion, wherein a stress releasing portion in which a diameter is smallest in an area between said heater connecting portion and said center-pole rear end portion is formed in said center pole.

A heater including: a rod-shaped ceramic heater including: a ceramic heater body extending in an axial direction and having a heating-element at its leading end portion for generating heat when energized; and first and second energizing lead terminals extending from the heating element and exposed to an outer circumference of a trailing end side of the ceramic heater body; a cylindrical outer cylinder for holding the ceramic heater while protruding a leading end portion and a trailing end portion of the ceramic heater; and a core rod arranged on said trailing end side of the ceramic heater in an axial direction and connected electrically with the first lead terminal, wherein the heater further includes: a ring member including: a ring leading end portion fixed by a tight fitting on an outer circumference of a trailing end side of the ceramic heater and connected electrically with the first lead terminal; and a ring trailing end portion protruding backward from a trailing end of the ceramic heater; and a metallic lead for connecting the ring trailing end portion and the core rod electrically.

Ceramic heater with ring member electrically connecting the heater to lead terminal core rod

A glow plug includes a ceramic heater having a resistance-heating element embedded at its end portion. In order to supply electricity to the resistance-heating element, first and second heater terminals are exposed on the surface of the ceramic heater. First and second terminal rings, which serve as metallic fitting members, are shrink-fitted to the surface of the ceramic heater in such a manner as to cover and be electrically connected to the exposed first and second heater terminals. A metal layer not higher than Ni in ionization tendency is formed on the inner circumferential surface of each of the first and second terminal rings.

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Nagoya, Japan

Shinya Murakoshi