Thermostat or the like having twisted bimetal strip therein

Claim 2

A thermostat, thermal protector or the like connectable to an electric circuit comprising a casing having at least one open ed, a bimetal strip extending into the casing as a cantilever, insulation means securing said strip at the initially open end of said casing and sealing said open end and around said bimetal strip, and opposed contact means operatively positioned in said casing including one contact means on the free end of said bimetal strip for movement into and out of engagement with the other contact means for circuit openings and closing action, characterized by said bimetal strip being of generally rectangular shape in section and having layers of different metals on the opposite longer surfaces thereof, said bimetal strip having a substantially 180* twist therein intermediate the ends thereof in a section of reduced width to form two axially spaced sections in said bimetal strip whereby different bending actions are obtained in said sections when heated, the secured end section of said strip being of the major length of the said strip and the free end section of minor length.

Claim 3

A thermostat, thermal protector or the liKe as in claim 1 where the major length is a relatively long axial section and the minor length is a relatively short axial section.

Claim 4

A thermostat, thermal protector or the like as in claim 1 where said bimetal strip has a notch provided on each side thereof at the twisted portion thereof.

Claim 5

A thermostat thermal protector or the like as in claim 3 where each notch extends into said bimetal strip up to one third the width thereof.

Claim 6

A thermostat, thermal protector or the like as in claim 1 where said bimetal strip has a heater metal strip secured to it at its cantilevered end, said heater strip projecting beyond said bimetal strip, and one of said contact means is secured to said heater. 6 A thermostat, thermal protector or the like comprising a conductive casing having at least one open end, a bimetal strip extending into the casing as a cantilever, insulation means securing said strip at the initially open end of said casing and sealing said open end and around said bimetal strip, and opposed contact means on said casing and the free end of said bimetal strip, characterized by said strip having layers of different metals on the vertically opposite surfaces thereof, said strip at the free end thereof having a different metal on the top surface thereof than at and adjacent the secured end thereof, said strip having a substantially 180* twist therein intermediate the ends thereof, said strip adjacent the supported end thereof moves upwardly when heated and said strip at the free end thereof moves downwardly when heated whereby a circuit formed by the thermostat when said contacts engage is opened only after said free end portion curves downwardly to an appreciable extent; and the open and close circuit cycle rate being controlled by the axial location of the twist in said strip in the cantilever portion thereof, the distance from the secured end of said strip to the adjacent edge of the twist being longer than the distance from the contact carried by the free end of the strip to the adjacent edge of the twist.

Claim 7

A thermostat as in claim 6 where the 180* reversed position of the free end of the single bimetal strip results in a temperature of contact closing being significantly lower than the temperature of contact opening.

Claim 8

A thermostat, thermal protector or the like as in claim 6 where said strip has a second metal strip secured to and projecting beyond the cantilevered end thereof, and one of said contacts is secured to said second strip which is a heater strip.

Claim 9

A thermostat as in claim 6 where the position of the bimetal strip in relation to normal is reversed and the bimetal strip in the longer section thereof tends to curve toward a circuit closing position under heating conditions and wherein the temperature of contact closing is significantly higher than the temperature of contact opening and where the longer length section has the high expansion part of the bimetal on the opposite side thereof than that side to which the contact is attached.