Thermally responsive electrical switch

A single phase motor protector comprising:

• a generally cup shaped metallic housing being elongated along a longitudinal axis from first to second opposite ends and having a closed top wall, a side wall having a free end extending around the circumference of the top wall and forming a rounded junction therewith, the top and side walls forming a switch chamber, a calibration rill formed in the top wall extending from the first end to a calibration ridge along the longitudinal axis, a bottom wall of the calibration rill forming a rigid flat bottom surface lying in a first plane, a weld projection formed on the calibration rill extending into the switch chamber,
• an elongated thermostatic disc having first and second ends disposed along the longitudinal axis, the first end of the thermostatic disc welded to the calibration rill at the weld projection and generally lying in a plane parallel to the first plane, the thermostatic disc formed with a ring shaped dish shaped configuration in a central portion of the thermostatic disc, the thermostatic disc being movable between oppositely dished configurations in response to selected changes in temperature, a movable electrical contact mounted on the thermostatic disc at the second end thereof,
• an electrically conductive header plate received on the free end of the side wall and hermetically attached thereto and lying in a second plane, a terminal pin extending through an aperture in the electrically conductive header plate into the switch chamber, the terminal pin electrically separated from the electrically conductive header plate by electrical insulating material,
• an electrically conductive heater having a first end fixed to the terminal pin and extending for a first segment generally parallel to the second plane, a second segment of the heater bent toward the header at the end of the first segment and continuing on in a third segment bent to extend generally parallel to the second plane, a stationary electrical contact mounted on the third segment with the movable electrical contact adapted to move into and out of engagement with the stationary electrical contact, and
• an electrical insulator plate disposed on the header plate interposed between the heater and the electrically conductive header plate, the insulator plate covering the electrical insulating material around the terminal pin.

In a single phase motor protector having a generally cup shaped metallic housing elongated along a longitudinal axis from first to second opposite ends and having a closed top wall, a side wall having a free end extending around the circumference of the top wall,

• the method steps comprising the steps of forming a calibration rill in the top wall having longitudinally extending side walls extending down to a flat bottom surface to rigidify the flat bottom surface, the calibration rill extending from the first end of the metallic housing to a calibration ridge along the longitudinal axis,
• taking an elongated thermostatic disc having first and second ends,
• mounting the first end of the thermostatic disc to the calibration rill, the disc having a ring shaped deformation in a central portion of the thermostatic disc disposed adjacent to the calibration ridge, the thermostatic disc being movable between oppositely dished deformation configurations in response to selected changes in temperature, a movable electrical contact mounted on the thermostatic disc at the second end thereof beyond the ring shaped deformation and being movable into and out of engagement with a stationary electrical contact,
• calibrating the motor protector by deforming the entire flat bottom surface of the calibration rill by rotating the flat bottom surface about the first end of the metallic housing to adjust the calibration ridge relative to the ring shaped deformation thereby adjusting the performance of the thermostatic disc.