Electric heaters

Claim 2

An electric heater, comprising: a tubular metal sheath, electrical-insulating, heat-conducting material transversely filling said sheath and extending for substantially the length thereof, a heating resistance wire extending longitudinally of said sheath and through said material, a pair of thermocouple wires of dissimilar metals extending longitudinally of said sheath and through said material in laterally spaced relation with respect to said resistance wire, said material electrically insulating said resistance wire and said thermocouple wires from each other and said sheath, terminal means extending from said resistance wire and outwardly of one end of said sheath for connection to a source of electricity for energizing said resistance wire to produce heat, said thermocouple wires having terminal portions extending outwardly of said sheath one end for connection to a temperature responsive device, said thermocouple wires being connected to each other at the opposite end of said sheath to form a heat sensing junction adjoining said sheath opposite end and be responsive to thermal conditions thereat, but being disposed within the transverse confines of said sheath opposite end for protection, a metal disc hermetically closing said opposite end of said sheath, the inner wall surface of said disc being disposed adjacent to said heat sensing junction, and, said thermocouple wires are connected to each other through said metal disc.

Claim 3

An electric heater, comprising: a tubular metal sheath, an electrical-insulating, heat-conducting ceramic core extending for a major portion of the length thereof and having two pairs of longitudinal openings through said sheath, means supporting said core centrally of said sheath, a helically coiled heating resistance wire extending longitudinally of said sheath adjacent said core and spaced inwardly from said metal sheath, a pair of thermocouple wires of dissimilar metals extending longitudinally of said core through the coil of said resistance wire and through one pair of said core openings, said core thereby electrically insulating said resistance wire and said thermocouple wires from each other and supporting said thermocouple and resistance wires in fixed spaced relation within said sheath, terminal means extending from said resistance wire through the other pair of said core openings and outwardly of one end of said sheath for connection to a source of electricity for energizing said resistance wire to produce heat, said thermocouple wires having terminal portions extending outwardly of said sheath one end and from said pair of core openings for connection to a temperature responsive device, said thermocouple wires being connected to each other at the opposite end of said sheath and longitudinally outwardly from said resistance wires to form a heat sensing junction adjoining said sheath opposite end and be responsive to ambient thermal conditions thereat, with said junction being disposed witHin the transverse confines of said sheath opposite end for protection, and, a metal closure disc hermetically sealing said sheath at said opposite end.

Claim 4

An electric heater, comprising: a tubular metal sheath, an electrical-insulating, heat-conducting ceramic core extending for a major portion of the length thereof and having two pairs of longitudinal openings through said sheath, means supporting said core centrally of said sheath, a helically coiled heating resistance wire extending longitudinally of said sheath adjacent said core and spaced inwardly from said metal sheath, a pair of thermocouple wires of dissimilar metals extending longitudinally of said core through the coil of said resistance wire and through one pair of said core openings, said core thereby electrically insulating said resistance wire and said thermocouple wires from each other and supporting said thermocouple and resistance wires in fixed spaced relation within said sheath, terminal means extending from said resistance wire through the other pair of said core openings and outwardly of one end of said sheath for connection to a source of electricity for energizing said resistance wire to produce heat, said thermocouple wires having terminal portions extending outwardly of said sheath one end and from said pair of core openings for connection to a temperature responsive device, said thermocouple wires being connected to each other at the opposite end of said sheath and longitudinally outwardly from said resistance wires to form a heat sensing junction adjoining said sheath opposite end and be responsive to ambient thermal conditions thereat, with said junction being disposed witHin the transverse confines of said sheath opposite end for protection, and, a metal closure disc hermetically sealing said sheath at said opposite end.

Claim 5

The construction according to claim 2 wherein the inner wall surface of said disc is in engagement with said sensing junction.

Claim 6

The construction according to claim 1 wherein the inner wall surface of said metal disc is in engagement with said sensing junction.

Claim 7

The construction according to claim 2 wherein said thermocouple wires are connected to said metal disc and are thereby electrically connected together.