Ngk Spark Plug Company, Limited

Tsuneo Ito

Shinichi Yokoi

Junichi Kagawa

A ceramic heater includes a cylindrical member; a ceramic heating member, which is disposed within the cylindrical member such that an end portion thereof is projected from an end of the cylindrical member; and a metallic shell, which surrounds the cylindrical member. The ceramic heating member includes a ceramic body and a U-shaped conductive ceramic element, which is embedded in an end portion of the ceramic body. A direction-changing portion of the conductive ceramic element generates heat through electrical resistance when electricity is supplied to the conductive ceramic element through electrodes connected to the end portions of the conductive ceramic element. The electrodes are disposed such that the distance L between the ends of the electrodes and the end of the metallic shell satisfies the expression L&lE;1 mm, where the distance L is considered negative when the ends of the electrodes are located within the metallic shell.

Glow plug with ceramic heating element having electrode attached thereto

A method of making a ceramic heater by preparing a heating coil having a circular cross-section and bending it into a U-shaped form. Lead wires are connected to the ends of the U-shaped coil; the coil is embedded in a ceramic powder to form a preform having a substantially rectangular cross-section. The preform is compacted under heat to reduce the length of the rectangular cross-section and deform the coil embedded therein into a coil having an oval cross-section. The preform is sintered to form a ceramic product having a substantially circular cross-section and then ground to form a product having a circular cross-section.

Method for manufacturing a ceramic heater

A ceramic heater including a ceramic insulator having a circular cross section, and a heating coil having an oval cross section, embedded in the insulator along the length thereof, and bent in a U-shaped form with the bend adjacent one end of the insulator. One of a pair of parallel coil portions defining the U-shaped coil has a long cross sectional diameter lying parallel to that of the other coil portion. The diameter of a cylinder defined by the outer surfaces of the coil portions and the outside diameter of the insulator have a ratio of 35:100 to 70:100.

Ceramic heater

A nickel alloy for spark plug electrodes consisting essentially of, by weight percent,

Nickel alloy for spark plug electrodes

A nickel alloy for use in a heater for a glow plug, which comprises pure nickel and 0.05 to 2.0% by weight of a metal such as yttrium, zirconium or ruthenium, which does not form a solid solution with nickel.

Nickel alloy heater in glow plug

An alloy for spark plug center electrodes comprising about 1 to about 10% by weight of chromium, about 30 to about 70% by weight of palladium and the balance gold.

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Nagoya, Japan

Tsuneo Ito