Abstract: There is disclosed glow plug for a diesel engine provided with an elongated ceramic heater retained by an opening end of a hollow holder with one end of said ceramic heater being projected toward the outside. The ceramic heater comprises an insulating tubular section of an insulating ceramic material, and a heating body as a continuous conductive section formed so as to cover the outer peripheral portion, the outermost portion and the hollow portion of the insulating tubular section with a conductive ceramic material, the heating body being formed in a manner that the thickness of at least the outer peripheral portion of the insulating tubular member in the vicinity of said one end of the ceramic heater is thinner than that of other portions thereof. The insulating tubular section and the heating body constituting the ceramic heater are integrally formed with the ceramic material which can select insulating property and conductive property by adjusting an amount of titanium nitride added into .beta.

Abstract: A self-regulating temperature controlled glow plug has a hollow metal holder, a rod-like ceramic heater and a power control heater. The ceramic heater extends from one end of the holder and has embedded therein a first resistor of tungsten alloyed with rhenium or molybdenum. The power control heater includes a second resistor embedded in a dense mass of powdered insulation material filling a tubular metallic sheath. The sheath is positioned in the holder with its central portion held in spaced relationship thereto by a thermally insulating spacer at least one end thereof. The second resistor is made of tungsten, iron or nickel, has a positive temperature coefficient of resistance at least equal to and a heating capacity greater than the first resistor, and is connected in series with the first resistor.

Abstract: In a glow plug for use in a diesel engine of the type wherein a heater rod is connected to one end of a hollow holder, and an external connecting terminal is inserted into the other end of the hollow holder through an electric insulator and electrically connected to the heater rod, an integrally combined terminal unit including a metal pipe, an electric insulator and the external connecting terminal embedded in the insulator is prepared. After inserting the terminal unit into the other end of the hollow holder, an external pressure is applied to the other end to deform the metal pipe for firmly bonding the metal pipe to the insulator. Thereafter an end surface of the other end of the hollow holder is caulked to form an annular ring that holds the inserted terminal unit. With this construction, the completed glow plug is maintained in a perfect air tight state regardless of the variation in the ambient temperature.

Abstract: In a glow plug for use in a diesel engine of the type wherein a heater rod is connected to one end of a hollow holder, and an external connecting terminal is inserted into the other end of the hollow holder through an electric insulator and electrically connected to the heater rod, an integrally combined terminal unit including a metal pipe, an electric insulator and the external connecting terminal embedded in the insulator is prepared. After inserting the terminal unit into the other end of the hollow holder, an external pressure is applied to the other end to deform the metal pipe for firmly bonding the metal pipe to the insulator. Thereafter an end surface of the other end of the hollow holder is caulked to form an annular ring that holds the inserted terminal unit. With this construction, the completed glow plug is maintained in a perfect air tight state regardless of the variation in the ambient temperature.

Abstract: In a glow plug, a pair of ceramic rods having longitudinal bonding surfaces are used as a heating rod. A resistor including a heater, and a pair of lead portions connected to both ends of the heater and extending to rear ends of the ceramic rods is continuously disposed on one bonding surface of the ceramic rods. One of the lead portions extends through a hollow metal holder, while the other lead portion is connected to an external connecting terminal mounted through an insulating member.