Electro-thermal relay actuator

Claim 2

An actuator mechanism comprising a bimetal strip, the bimetal strip including two contiguous sections having opposite bending action with change in temperature, a thin coating of electrical insulation bonded to a portion of the surface of the strip, a thin electrically resistive heater layer bonded to the surface of the coating and being positioned on only one of said sections of the bimetal strip, the insulation coating being sufficiently thin to provide good thermal conductivity between the resistive layer and the bimetal, means for connecting a source of electrical current across the resistive layer, and means supporting the strip at one end in cantilever fashion, the other end of the strip being movable with bending of said one section by the resistive layer.

Claim 3

Apparatus of claim 1 including a heat sink adjustably positioned adjacent to but spaced from the resistive layer for absorbing heat generated by the resisitive layer.

Claim 4

Apparatus of claim 1 further comprising a pair of electrical contacts, and means actuated by movement of the bimetal strip for opening and closing said contacts to make and break an electrical current path.

Claim 5

An actuator mechanism comprising a bimetal strip, a thin coating of electrical insulation bonded to a portion of the surface of the strip, a thin electrically resistive heater layer bonded to the surface of the coating, the insulation coatinG being sufficiently thin to provide good thermal conductivity between the resistive layer and the bimetal, means for connecting a source of electrical current across the resistive layer, means supporting the strip at one end in cantilever fashion, the other end of the strip being movable with bending of the bimetal strip, a flat spring anchored on one end, a pivot engaging the spring at an intermediate position, the pivot being positioned to cause the flat spring to bow, means engaging the moving end of the bimetal with the flat spring at a point between the pivot and anchored end, the bimetal strip urging the flat spring past the center line between the anchor end and the pivot, a pair of electrical contacts, and means opening and closing the electrical contacts with rotation of the spring about said pivot.

Claim 6

An actuator mechanism comprising a bimetal strip, a thin coating of electrical insulation bonded to a portion of the surface of the strip, a thin electrically resistive heater layer bonded to the surface of the coating, the insulation coatinG being sufficiently thin to provide good thermal conductivity between the resistive layer and the bimetal, means for connecting a source of electrical current across the resistive layer, means supporting the strip at one end in cantilever fashion, the other end of the strip being movable with bending of the bimetal strip, a flat spring anchored on one end, a pivot engaging the spring at an intermediate position, the pivot being positioned to cause the flat spring to bow, means engaging the moving end of the bimetal with the flat spring at a point between the pivot and anchored end, the bimetal strip urging the flat spring past the center line between the anchor end and the pivot, a pair of electrical contacts, and means opening and closing the electrical contacts with rotation of the spring about said pivot.

Claim 7

The apparatus of claim 4 wherein the flat spring has a section adjacent the anchored end that has a higher spring constant than the remaining section adjacent the pivoted end.

Claim 8

An actuator mechanism comprising a bimetal strip, a thin coating of electrical insulation bonded to a portion of the surface of the strip, a thin electrically resistive heater layer bonded to the surface of the coating, the insulation coating being sufficiently thin to provide good thermal conductivity between the resistive layer and the bimetal, means for connecting a source of electrical current across the resistive layer, means constraining the ends of the bimetal strip to compress the strip into an S-shape in the center portion of the strip, the center of the compressed strip having an unstable equilibrium point corresponding to the maximum energy state of the compressed strip, the equilibrium point being shifted laterally by heating and cooling of the bimetal, and spaced limit means on either side of the center of the strip for restricting lateral movement of the center of the strip in either direction, the spacing being such that the equilibrium point shifts beyond the limits of the limit means with heating and cooling of the bimetal.

Claim 9

An actuator mechanism comprising a bimetal strip, a thin coating of electrical insulation bonded to a portion of the surface of the strip, a thin electrically resistive heater layer bonded to the surface of the coating, the insulation coating being sufficiently thin to provide good thermal conductivity between the resistive layer and the bimetal, means for connecting a source of electrical current across the resistive layer, means constraining the ends of the bimetal strip to compress the strip into an S-shape in the center portion of the strip, the center of the compressed strip having an unstable equilibrium point corresponding to the maximum energy state of the compressed strip, the equilibrium point being shifted laterally by heating and cooling of the bimetal, and spaced limit means on either side of the center of the strip for restricting lateral movement of the center of the strip in either direction, the spacing being such that the equilibrium point shifts beyond the limits of the limit means with heating and cooling of the bimetal.

Claim 10

Apparatus of claim 6 wherein the limit means include a pair of fixed electrical contacts positioned on opposite sides of the strip, and a contact carried by the strip and movable with displacement of the center of the strip into contact with either of the fixed contacts.

Claim 11

Apparatus of claim 7 wherein both fixed contacts are positioned to limit movement of the center of the strip entirely to one side of the equilibrium point of the compressed strip at the ambient temperature.

Claim 12

Apparatus of claim 7 wherein the fixed contacts are positioned on either side of the equilibrium point of the compressed strip at the ambient temperature.

Claim 13

Apparatus of claim 9 including a second resistive heater layer, and means connecting a source of an electrical current, the first mentioned and second resistive layers being positioned respectively on the two loops of the S-shaped strip.

Claim 14

A switching device comprising a bimetallic strip, means constraining the ends of the strip to compress the center portion of the strip into an S-shape, the center of the compressed strip having an unstable equilibrium point corresponding to the maximum energy state of the compressed strip, the equilibrium point being shifted by heating and cooling of the bimetal strip, spaced limit means positioned on either side of the center of the strip for restricting lateral movement of the center of the strip, and means for heating the strip sufficiently to shift the equilibrium point outside the space between the spaced limit means.

Claim 15

A switching device comprising a bimetallic strip, means constraining the ends of the strip to compress the center portion of the strip into an S-shape, the center of the compressed strip having an unstable equilibrium point corresponding to the maximum energy state of the compressed strip, the equilibrium point being shifted by heating and cooling of the bimetal strip, spaced limit means positioned on either side of the center of the strip for restricting lateral movement of the center of the strip, and means for heating the strip sufficiently to shift the equilibrium point outside the space between the spaced limit means.

Claim 16

Apparatus of claim 11 wherein the limit means include a pair of fixed electrical contacts positioned on opposite sides of the strip, and a contact carried by the strip and movable with displacement of the center of the strip into contact with either of the fixed contacts.

Claim 17

Apparatus of claim 12 wherein both fixed contacts are positioned to limit movement of the center of the strip entirely to one side of the equilibriUm point of the compressed strip at the ambient temperature.

Claim 18

Apparatus of claim 12 wherein the fixed contacts are positioned on either side of the equilibrium point of the compressed strip at the ambient temperature.

Claim 19

Apparatus of claim 11 wherein the bimetal strip has two sections on either side of the center which bend in opposite directions with change in temperature.

Claim 20

Apparatus of claim 15 wherein the heater means heats only one of said sections of the strip.

Claim 21

Apparatus of claim 15 wherein the heater means includes means for separately heating each section of the bimetal strip.

Claim 22

Apparatus of claim 11 wherein the constraining means includes means for supporting at least one end of the strip in cantilever fashion.