Patent ID: 6667463
Filing Date: 2003-12-23
Classification: F23Q

Abstract:
A heater comprising:a metal sheath; a heating element that is connected to an inner surface of the metal sheath at one end thereof; a center pole that is extending from an opening of the metal sheath to an interior of the metal sheath and directly or indirectly connected to the heating element; an insulating material that is packed in the interior of the metal sheath; and an elastic packing, wherein the opening of the metal sheath is closed by sealing a gap between the metal sheath and the center pole with the elastic packing; and an axial length of a portion of the elastic packing, the portion is between the metal sheath and the center pole, and is not smaller than 2.5 mm, and a metal shell having an engagement portion, wherein the metal shell interfits the metal sheath by the engagement portion, the metal sheath has a fixed portion fixed to the metal shell and a small diameter portion having a smaller diameter than an inner diameter of the engagement portion, the small diameter portion being between the fixed portion and the opening, and an axial length of the small diameter portion is greater than the axial length of the portion of the elastic packing.