Patent ID: 8422871

Claim:
An immersion heater comprising a ceramic bottomed protecting tube, an insulating cylindrical body inserted into said ceramic bottomed protecting tube, a metal heating element held inside a spiral groove formed in an outer circumference surface of said insulating cylindrical body, an insulating cover closing an opening portion of said ceramic bottomed protecting tube, and first and second terminal rods, one-end portions of which are connected to a fore-end portion and a back-end portion of said metal heating element, respectively, and other-end portions of which pass through said insulating cover and are located outside said ceramic bottomed protecting tube, wherein: said metal heating element is a strip heating element, and one edge portion of said strip heating element is inserted into, and held in said spiral groove to form a spiral heating part, cylindrical-body supporting members that each have a diameter smaller than an inner diameter of said ceramic bottom protecting tube and larger than an outer diameter of the spiral heating part and are fitted into a hollow portion of said insulating cylindrical body are arranged in openings at a fore-end side and a back-end side of said insulating cylindrical body, respectively, a through-hole through which said first terminal rod connected to the fore-end portion of said metal heating element passes, and a notched portion through which a connection plate joined and fixed to a fore-end of said first terminal rod is inserted are formed in said cylindrical-body supporting member on the fore-end side, and a through-hole through which said first terminal rod passes, and a notched portion through which a connection plate joined and fixed to a fore-end of said second terminal rod is inserted are formed in said cylindrical-body supporting member on the back-end side.