Abstract: An electrode structure includes: a metallic electrode; a case for accommodating and holding the electrode, and one end of a lead wire connecting to the electrode; and an insulating member interposed between the electrode and the case in order to ensure insulation between the electrode and the case, in which structure a waterproof member is interposed between the case and the lead wire in order to prevent the incoming of water from between the case and the lead wire, and an electric heater havinging the above electrode structure.

Abstract: An electrode structure includes a metallic electrode having a configuration of a bending cylinder and having a plurality of members disposed successively in an axial direction of the electrode and mutually connected with adjacent member(s); a case for installing the metallic electrode and one end of a lead wire for electrification therein; and an insulating member which is positioned between the case and the electrode and which the case from the electrode. An electric heater includes a housing, a honeycomb structure installed in the housing, and the electrode structure for electrifying the honeycomb structure. The electrode structure exhibits excellent composability, waterproof ability, and gas sealability.

Abstract: A structure of an electrode unit for applying electricity to a conductible substance (4) installed in a metallic housing (2) has a metallic electrode (6) connected to a portion of the conductible substance (4), an insulating member (8, 8') positioned between the electrode (6) and the metallic housing (2), and a metallic sealing material (10,10') to be transformed by fastening a nut so as to secure sealability between the electrode (6) and the insulating member (8) and between the metallic housing (2) and the insulating member (8). The structure of an electrode unit is excellent in an insulating property and a gas sealability between the metallic housing (2) and electrode (6) and therefore has high reliability.

Abstract: A heater unit comprising (1) a honeycomb heater comprising (a) a metallic honeycomb structure having a large number of passages parallel to the direction of a gas flowing through the heater unit and (b) at least one electrode for electrification of the honeycomb structure, attached to the honeycomb structure, and (2) a metallic casing for holding the honeycomb heater (1) therein via at least one metallic supporting member, in which heater unit an insulation portion is provided at least either at the connection area where the honeycomb heater and the supporting member are connected or at the connection area where the supporting member and the casing are connected, and the supporting member has such a structure as to be able to absorb the displacement of the honeycomb heater which appears in a direction substantially perpendicular to said gas flow direction, and has a function of fixing the honeycomb heater against its displacement which appears in the gas flow direction.

Abstract: A multi-stage honeycomb heater includes: at least two honeycomb heaters electrically connected with each other and disposed along a stream of fluid; the two honeycomb heaters including furthest upstream honeycomb heater and a an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater; each of the two honeycomb heaters having an electrically conductive honeycomb structure the honeycomb structure of the upstream honeycomb heater having slits for adjusting its electrical resistance and/or element for adjusting heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater. Thus the upstream heater and the downstream heater can give similar temperature increases without a temperature distribution along a flow direction during the engine warm-up.