Illinois Tool Works Inc.

Bruce A Luxon

John K McVey

Larry L Sharp

A thermal switch for automatically opening a circuit when the ambient temperature exceeds a predetermined level is disclosed which utilizes a sensing pellet formed of an organic-glass bead mixture. The organic-glass bead pellet retains a pair of leads in contact with each other when the ambient temperature is below the melting temperature of the organic material. The addition of the glass beads to the temperature sensing pellet allows the compressive strength that is needed to hold the leads together to be more reliably controlled. In the process of combining the organic material and the glass beads, to form the pellet, the organic material is first melted so as to flow around the beads. Manufacture of the thermal-sensing pellet in this manner eliminates the voids which occur in the pressed organic pellets that are conventionally used in thermal sensing devices. The elimination of these voids increases the strength of the otherwise relatively fragile pellet thereby improving reliability of thermal switches which utilize the improved pellet of the present invention.

Thermal switch with organic-glass bead mixture sensing pellet

A thermal switch device for automatically opening a circuit when the ambient temperature is increased to a predetermined level. A pair of conductor wires arranged in side by side fashion are spring loaded into contact with one another by inserting the contact regions into a cup-shaped pellet of heat-fusible material. The cup is structurally secured within a nonconductive tubular casing with a layer of insulative cement. The lead regions of the wires are also securely anchored within the casing with an insulative cement.

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Bensenville, IL, United States of America

Bruce A Luxon