US Patent No. 10,194,489

ELECTRIC HEATER AND METHOD FOR MANUFACTURING ELECTRIC HEATER


Patent No. 10,194,489
Issue Date January 29, 2019
Title Electric Heater And Method For Manufacturing Electric Heater
Inventorship Shigeru Kobayashi, Takamatsu (JP)
Kazuo Hira, Takamatsu (JP)
Assignee

Claim of US Patent No. 10,194,489

1. An electric heater comprising:a heat transfer tube that has a hollow space inside the heat transfer tube, having distal and proximal ends in an axial direction of the heat transfer tube, each of the ends having an opening;
a heater body that is accommodated in the heat transfer tube, being formed with three parts that are an inner conductor, an outer conductor and a bent-back part,
a sealing resin that entirely fills a remaining of the hollow space, the remaining being defined as a space that is inside the heat transfer tube and not occupied with the heater body, wherein
these three parts are made of a main metal having a predetermined electrical resistivity,
the inner and outer conductors are coaxially disposed such that the inner conductor is inside the outer conductor, extending along to the axial direction of the heat transfer tube such that each of the conductors has distal and proximal ends in the axial direction, and an insulator intervening between the inner and outer conductors,
the distal ends of the conductors are connected with the bent-back part, and the bent-back part is positioned at a side of the distal end of the heat transfer tube, and the proximal ends of the conductors are positioned at the proximal end of the heat transfer tube such that these proximal ends of the conductors are exposed outside the heat transfer tube,
the outer conductor is further segmented into a heating part and a leading part,
the leading part extending from the proximal end toward the distal end of the heat transfer tube, and an outer surface of the leading part being covered by a cover metal that has an electrical resistivity lower than the electrical resistivity of the main metal,
the heating part being positioned closer to the distal end of the heat transfer tube than the leading part, and an outer surface of the heating part being not covered with the cover metal such that a resistance of the leading part per unit length is lower than that of the heating part, and that the heating part generates heat and conveys the heat toward the heat transfer tube when the heater body is electrified.