In a thermal protection circuit with two electrical connection terminals for an electrical device to be protected from overheating and at least one temperature-dependent switch, at least one electronic semiconductor switch for DC voltage is arranged.

A thermally responsive switch is provided with a sealed container having a housing and a cover plate secured to the housing; a couple of conductive thermal pins inserted into a couple of through holes provided on the cover plate and secured by an insulative filler; a stationary contact secured to one of the conductive thermal pins inside the container; a heater having one end connected to the other of the conductive terminal pins inside the container and the other end connected to the cover plate; a thermally responsive plate having one end connected to the housing and being configured to invert a direction of curvature thereof at a predetermined temperature; and a movable contact provided on the other end of the thermally responsive plate. The through holes are configured by cylindrical portions, only the cylindrical portions, the filler, and the conductive terminal pins being covered by an insulative resin.

A manufacture method of a concave disc-shaped structure of bimetal strip, particularly to one that is a coaxial positioning method of the guide hole which having elastic disc-shape structure bimetal strips not affected by external stress, which having a bimetal structure which outer edge will not be damaged and does not affect by stress while inner edge pulling closed to the outer edge, it includes: a bimetal strip, a lug, and an assembling jig, having two displaceable positioning holes, and use the guiding surface to make the two positioning holes gradually turn inside to condense to the combining surface of the lugs, so as to achieve the purpose of accurate positioning and combination.

A thermal protector (1) that switches an electric circuit of an electrical product includes first and second terminals (2,3) that are each connected to an external circuit, a first insulating block (4) that holds the first terminal (2), a second insulating block (5) that holds the second terminal (3), a base (6) that connects the first insulating block (4) and the second insulating block (5), a fixed contact (7) that is connected to the first terminal (2), a movable contact (8) that is arranged in a position that faces the fixed contact (7), a bimetal (9) whose curvature is reversed at a set temperature, and an elastically-deformable movable plate (10) that engages the bimetal (9) and on which the movable contact (8) is fixed, the movable plate (10) being connected to the second terminal (3) so as to be fixed on the base (6), wherein the bimetal (9) and the movable plate (10) are arranged to be within an area situated between the first insulating block (4) and the second insulating block (5), and are arranged to be non-parallel to every surface of the first and second insulating blocks (4,5).

A breaker (1) is provided with: a fixed piece (2) which has a fixed contact; a movable piece which has a movable contact at a front end portion and pushes the movable contact against the fixed contact to bring same into contact with each other; a thermally responsive element that deforms in accordance with a change in temperature and thereby actuates the movable piece so that the movable contact separates from the fixed contact; and a case body (71) of a resin case that accommodates the fixed piece (2), the movable piece, and the thermally responsive element. The case body (71) has recess portions (75, 77) which are recessed from a peripheral portion, and the fixed piece (2) has a withdrawal portion (25) that withdraws from the recess portions (75, 77) of the case body (71) by a predetermined first distance (D1) or more, and is embedded in the case body (71).

A protection device includes a movable arm, a fixed terminal, and a bimetallic member, and a casing that accommodates them, the bimetallic member is located either above or below the movable arm, one end of the bimetallic member applies force to one end of the movable arm, thereby holding one end of the movable arm and the fixed terminal in contact.

A heat-reactive switch includes an airtight container with a housing and a lid plate, two conductive terminal pins fixed in through-holes in the lid plate, a fixed contact point fixed on one of the conductive terminal pins, a heater connected to the other conductive terminal pin and to the lid plate, a heat-reactive plate connected to the housing internal surface, the bending direction becoming inverted at a predetermined temperature, and a mobile contact point provided at the end of the heat-reactive plate. A heating element has a plurality of serpentine portions made from a metal plate in ribbon form, disposed between the lid plate and the heat-reactive plate so as to be parallel thereto. At least two of the serpentine portions are disposed to face each other while sandwiching the conductive terminal pin. Each portion follows the inner peripheral surface of the housing and have planar portions facing each other.

A protection device is provided for electric appliances suitable for selectively connecting an electric appliance to a power supply line. The protection device includes a metal plate member, a composite metal blade, an insulating block for supporting the metal plate member and the composite metal blade, and a compensating resistor made en bloc with the metal plate member.

To enhance, in a cantilever bimetallic element, flexibility of setting a temperature of an inverting motion. A thermal protector includes a thermally actuated element having a substantially quadrangular non-fixed region, a fixed region that is connected to the non-fixed region along a longitudinal direction of the non-fixed region and is to be fixed to a stationary body, and a processed portion, a center of which is positioned inside a triangular region formed by a center of the non-fixed region and both ends of a boundary between the non-fixed region and the fixed region.