Ngk Spark Plug Company, Limited

Masakazu Nagasawa

Masato Taniguchi

Katsuhiko Tanaka

Hiroyuki Suzuki

Takaya Yoshikawa

Nobuyuki Hotta

A glow plug according to one embodiment of the present invention includes a cylindrical metallic shell, an electrode rod disposed in a rear portion of the metallic shell, a heater disposed in a front portion of the metallic shell, and an electric insulator provided between an inner surface of the metallic shell and a circumferential surface of the electrode rod to keep the electrode rod insulated from the metallic shell. The metallic shell has a portion caulked to the electrode rod at a location axially corresponding to the electric insulator so that the circumferential surface of the electrode rod becomes deformed to define therein a recessed portion. The caulked portion is engaged in the recessed portion with the caulked portion with the electric insulator interposed between the caulked portion and the recessed portion, thereby securing the electrode rod in the metallic shell.

Glow plug

In a glow plug configured such that a metallic, tubular member having a heater fixedly provided therein is joined to a metallic shell, an external-thread portion is formed on the outer circumferential surface of the metallic shell so as to allow the glow plug to be screwed into a plug-mounting hole formed in an engine head. An annular protrusion is formed on the outer circumferential surface of the metallic, tubular member in such a manner as to protrude radially outward, to annularly extend in the circumferential direction, and to be located in the vicinity of a distal end of the metallic shell. A distally-facing end face of the annular protrusion abuts an annular seat face in the mounting hole, and the metallic, tubular member and the metallic shell are joined such that a distal end face of the metallic shell abuts a rearward-facing end face of the annular protrusion.

Glow plug and glow-plug-mounting structure

A heater has a cylindrical metallic shell, a heater body partly disposed in a front end portion of the metallic shell, an electrode disposed in a rear portion of the metallic shell and electrically connected to the heater body, and a terminal adapted to be capped with an electric connector. The terminal includes a terminal body for power supply to the heater body through the electrode and an engaging portion formed on an outer circumferential surface of the terminal body so as to be engageable with the electric connector. The electrode and the terminal body are formed integrally with each other. Such a heater can maintain good electrical conduction from the terminal to the heater body with its simple structure throughout an extended period of time.

Heater

The present invention provides an inexpensive heater exhibiting good gas-tightness, as well as a method for manufacturing the same. The heater includes a cylindrical metallic shell having a through-hole with a heating element disposed in the through-hole such that a portion projects from one end of the shell. The heater is adapted to generate heat upon application of electricity thereto. A rod-like axial member has a coil lead for electrically connecting a portion of the axial member and the heating element. A gas-tight seal member formed of an insulating polymeric material is interposed between the axial member and the inner surface of the through-hole in such a manner to surround the outer circumferential surface of the axial member. A crimped portion of the metallic shell brings the gas-tight seal member into close contact with the outer circumferential surface of the axial member and the inner wall surface of the through-hole form a gas tight seal.

Heater and method for manufacturing the same

In a glow plug controller, a glow plug fixed to an engine comprises a heater and a ceramic substrate having an exposed portion which is exposed to the interior of a combustion chamber A glow plug control apparatus causes ECU to control the energization of the heater of the glow plug to keep the surface temperature Ts of the exposed portion to not lower than 500&deg; C. Further, ionic current Ii is measured using the glow plug Switches and switch from the energization of the glow plug to the detection of ionic current or vice versa in response to a command signal from ECU

Growing community of inventors

Aichi, Japan

Masakazu Nagasawa