Temperature sensitive pellet type thermal fuse

A temperature sensitive pellet type thermal fuse comprising:

• a cylindrical case which is electrically conductive, and has a first end and a second end;
• a temperature sensitive pellet which is disposed inside the cylindrical case proximate the second end, and is configured to melt at a specific temperature;
• an insulating tube which is disposed inside the cylindrical case proximate the first end;
• a first lead which is inserted into the insulating tube, and has a fixed contact portion at an inner end of the first lead;
• a movable contact which is movably disposed inside the cylindrical case, and electrically contacts the cylindrical case;
• a weak compression spring which is interposed between a portion of the insulating tube and the movable contact;
• a strong compression spring which is stronger than the weak compression spring, and is interposed between the temperature sensitive pellet and the movable contact;
• and
• a second lead which is connected to the second end of the cylindrical case;
• wherein:
• the movable contact includes a movable contact main body and a projecting contact portion which projects from the movable contact main body toward the fixed contact portion of the first lead,
• the projecting contact portion of the movable contact and the fixed contact portion of the first lead are in contact with one another on a contact plane inside an axial bore of the insulating tube, and
• the projecting contact portion of the movable contact is formed by embossing.

A temperature sensitive pellet type thermal fuse comprising:

• a cylindrical case which is electrically conductive, and has a first end and a second end;
• a temperature sensitive pellet which is disposed inside the cylindrical case proximate the second end, and is configured to melt at a specific temperature;
• an insulating tube which is disposed inside the cylindrical case proximate the first end;
• a first lead which is inserted into the insulating tube, and has a fixed contact portion at an inner end of the first lead;
• a movable contact which is movably disposed inside the cylindrical case, and electrically contacts the cylindrical case:
• a weak compression spring which is interposed between a portion of the insulating tube and the movable contact;
• a strong compression spring which is stronger than the weak compression spring, and is interposed between the temperature sensitive pellet and the movable contact;
• and
• a second lead which is connected to the second end of the cylindrical case;
• wherein:
• the movable contact includes a movable contact main body and a projecting contact portion which projects from the movable contact main body toward the fixed contact portion of the first lead,
• the projecting contact portion of the movable contact and the fixed contact portion of the first lead are in contact with one another on a contact plane inside an axial bore of the insulating tube,
• the temperature sensitive pellet type thermal fuse further comprises a metal plate arranged in contact with the movable contact main body, and
• the projecting contact portion comprises a projecting contact member which is inserted through the movable contact main body and the metal plate, and is fixed to the movable contact main body.