Thermally responsive switch and method of manufacturing same

A thermally responsive switch comprising:

• a sealed container formed of a metal housing and a cover plate secured airtight to an open end of the housing;
• two conductive terminal pins respectively inserted into two through holes provided on the cover plate and respectively secured airtight by an electrically insulative filler;
• a stationary contact secured to one of the two conductive terminal pins inside the sealed container;
• a heater having one end connected to the other of the two conductive terminal pins inside the sealed container and the other end connected to the cover plate;
• a thermally responsive plate having one end connected to an inner surface of the housing and being configured to invert a direction of curvature thereof at a predetermined temperature;
• a movable contact provided on the other end of the thermally responsive plate and being configured for intermittent contact with the stationary contact,
• wherein when the movable contact and the stationary contact are welded, the heater is configured to melt so that an electric path is cutoff;
• two cylindrical portions projecting outwardly from the cover plate to surround the two through holes;
• and
• an electrically insulative resin covering only the two cylindrical portions, the filler, and the two conductive terminal pins,
• wherein the resin is a solidified melt of a ring-shaped resin material covering only the two cylindrical portions, the filler, and the two conductive terminal pins, and
• wherein the resin material prior to being melted has an inner diameter being greater than an outer diameter of the two conductive terminal pins and an outer diameter being less than a sum of an outer diameter of the two cylindrical portions and 2 mm.