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US 3,946,352 AGranted
Thermally responsive switch
AssigneeTexas Instruments Incorporated
InventorHjalmar N. Nelson
Life of this patent
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AssigneeTexas Instruments Incorporated
InventorHjalmar N. Nelson
Estimating the term…
A thermally responsive electrical switch characterized by low cost and long reliable service life includes a precalibrated snap-acting thermostatic member which is positioned outside the electrical circuit of the switch in heat-transfer relation to heater terminal means in the switch, whereby the member is economically mounted without requiring calibration during or after switch assembly and is arranged to avoid the deleterious effects of high current surges in the switch but is responsive to the occurrence of selected current levels in the switch to open the switch with snap action. Preferably spring biased cam means cooperate with the snap-acting member to permit initial snapping movement of the member while the member is free of significant loading, thereby to assure that such snapping movement occurs at precisely predetermined temperatures throughout the life of the switch.
A thermally responsive switch comprising a casing, first terminal means, complementary terminal means cooperating with said first terminal means to define a current path through said switch, said complementary terminal means having a contact arm portion movable between positions engaging and disengaging said first terminal means to open and close said circuit path through said switch and resiliently biased to one of said positions, means on said casing slidably receiving said first and complementary terminal means for precisely locating said terminal means within said casing, a multilayer thermostatic member movable in a predetermined manner in response to predetermined changes in temperature thereof, and means on said casing slidably receiving said thermostatic member for precisely locating said thermostatic member outside said circuit path in position to move said terminal arm portion between said open and closed circuit positions in response to said selected changes in temperature of said member.
A thermally responsive switch comprising a casing with a plurality of slots to receive components of said switch, a snap-acting dish-shaped bimetallic member having one end slidably received for precise location in one of said slots and being movable at the other end from a closed contacts position to an inverted dish-shaped open contacts position, first terminal means slidably received for precise location by another of said slots, and complementary terminal means having a movable contact arm with a first end slidably received in still another of said slots and second end biased so that said arm positioned closely adjacent said bimetallic member has one end in contact with complementary terminal means when said member is in the closed contacts position, said complementary terminal means cooperating with said first terminal means to define a current path through said switch, said bimetallic member being spaced from said current path when switch carries current.
A thermally-responsive electrical switch adapted to open an electrical circuit in response to flow of selected current in the circuit, said switch comprising a casing of dielectric material having a bottom, having side-walls upstanding from said bottom to define a casing chamber, and having an open casing top, said casing having a pair of slots in a first one of said casing side-walls open at said casing top and extending from said casing chamber exteriorly of said casing, having an additional U-shaped slot in a second, opposite casing side-wall which is open at said casing top and which has its opposite ends opening into said casing chamber, and having a third L-shaped slot in said second casing side-wall which is open at said casing top and which has one of its ends opening into said casing chamber between said ends of said U-shaped slot, a first terminal slidably disposed in one of said pair of slots with one end of said terminal in said casing chamber and with an opposite terminal end extending from said casing, a second terminal having an end portion slidably disposed in the other of said pair of slots to extend from said casing, having a U-shaped portion slidably received in said U-shaped casing slot, having a heater portion extending between said U-shaped and end portions of said second terminal through said casing chamber, and having a resilient portion extending in cantilever relation from said U-shaped terminal portion into said casing chamber, said resilient arm portion being normally biased to engage said first terminal to close an electrical circuit through said switch and being movable to disengage said first terminal to open said circuit, and a thermostatic member having an L-shaped tab portion slidably received in said third casing slot and having a dish-shaped snap-acting portion extending in cantilever relation into said casing chamber in selected closely spaced heat-transfer relation to said heater portion of said second terminal, said snap-acting portion being normally disposed in a first dished configuration to permit said movable portion of said second terminal to remain in said closed circuit position but being adapted to be heated by selected current flow in said heater terminal portion to move with snap-action to an inverted dished configuration and to engage a distal end of said member with said movable portion of said second terminal to move said movable terminal portion to said open circuit position.
A thermally responsive switch comprising a casing, a snap-acting dish-shaped bimetallic member movable from a closed contacts position to an inverted dish-shaped open contacts position, first terminal means, complementary terminal means cooperating with said first terminal means to define a current path through said switch, said complementary terminal means having a contact arm portion movable between said closed contacts position and said open contacts position, and a cam which moves between a first cam position and a second cam position as said bimetallic member and contact arm move between said closed contacts position and said open contacts position thereby allowing said bimetallic member to be free from external forces when snapping.
A thermally-responsive electrical switch comprising a base, first terminal means mounted on said base, second terminal means mounted on said base having an arm movable between a closed circuit position engaging said first terminal means and an open circuit position spaced from said first terminal means, said arm being normally biased to one of said circuit positions, cam means mounted relative to said arm for movement between a first cam position permitting movement of said arm in response to said arm bias and a second cam position preventing movement of said arm in response to said arm bias, said cam means being normally biased to said second cam position and having a cam surface engageable for moving said cam means to said first cam position, and a multilayer thermostat metal member having a mounting portion and having a dished portion movable in response to changes in temperature of said member, said movable member portion being initially movable in a first direction with creep action and then with snap-action as said member is heated for moving said movable member portion from an original dished configuration to an inverted dished configuration and being initially movable in an opposite direction with creep action and then with snap-action as said member is subsequently cooled for returning said movable member portion to said original dished configuration, said mounting portion of said member being secured relative to said base, said member mounting permitting movement of said movable member portion in one direction with snap-action at a first temperature to engage and move said arm into said other circuit position against said arm bias and permitting movement of said cam means in response to said cam bias, permitting movement of said movable arm portion in the other of said directions with creep action at a second temperature to permit said arm to disengage said member from said arm while said arm is retained in said other circuit position by said cam means, and for permitting subsequent movement of said movable arm portion in said other direction with snap-action while said member is disengaged from said cam to engage said member with said cam surface to move said cam means to said first cam position to permit said arm to return to said one circuit position in response to said arm bias.
Dependencies are inferred from the claim text.