Patent ID: 8519816

Claim:
An external operation thermal protector which interrupts an electric circuit using a bimetal element whose warping direction is inverted at a predetermined temperature in reaction to an ambient temperature, comprising: a body casing; a fixed conductor having a fixed contact point at one end; a first terminal formed at an end of the fixed conductor for connection to an external circuit external to the body casing; a movable plate having a movable contact point at a position opposite the fixed contact point on a free end side, having a spring property for allowing the movable contact point to have a predetermined contact pressure at a contact point, being fixed to the body casing at an end opposite the free end side through an insulating member, and changing a position of the free end side by inversion of the bimetal element; a second terminal connected to the movable plate for external connection; a resistance element module having a polymer PTC element provided with an inner resistance element and electrodes on both surfaces of the inner resistance element, first and second terminal plates soldered to the electrodes on both sides of the polymer PTC element, and first and second connection units laid together after being extended parallel to electrode surfaces from the first and second terminal plates, having the first connection unit connected to the second terminal at an end opposite the free end of the movable plate, and having the first terminal plate fixed to the body casing through the movable plate and the insulating member; and a third terminal formed by the second connection unit of the resistance element module for external connection external to the body casing, wherein; a gap for absorbing volume expansion by heat generated by the polymer PTC element is provided between the upper surface of the second terminal plate and an inner wall of the body casing; the trip temperature at which the resistance of the polymer PTC element suddenly changes is set to be higher than the inversion operation temperature of the bimetal element; and when a current is led to the second and third terminals, the polymer PTC element forcibly enters the trip state, and heats and operates the bimetal element, thereby interrupting the current between the first and second terminals.