Electricity: electrothermally or thermally actuated switches – Thermally actuated switches – With mechanical timing means
Patent
1997-05-05
1999-03-02
Picard, Leo P.
Electricity: electrothermally or thermally actuated switches
Thermally actuated switches
With mechanical timing means
337369, 337327, 337305, 337309, 337311, 337312, 337324, H01H 3702, H01H 3714, H01H 3732, H01H 3752
Patent
active
058776702
ABSTRACT:
A user adjustable switching controller for duty cycle regulating flow of current to an electrical load such as a resistance heater, particularly for cooking appliances. A load current switch, when closed by a user operated cam also energizes a heat motor which includes a resistive strip attached to one active leg of a U-shaped bi-metal member. In one embodiment the integrally formed load current switch snap spring is securely attached to the heated leg of a U-shaped bi-metal and the moveable contact arm pivoted on the base. The other leg of the U-shaped bi-metal is anchored to a base including one of the load-connecting stationary terminals; and, the anchored leg serves to provide ambient temperature compensation. In another embodiment, the integrally formed blade spring of the moveable contact member is pivoted on the active leg of the U-shaped bi-metal and the moveable contact arm welded to the base. User rotation of the cam deflects a bias spring which acts on the portion of the bi-metal attached to the load switch snap spring to effect closing of the load current switch and energization of the heat motor. Heating of the bi-metal causes warpage which overcomes the bias spring to open the load switch and shut off the heat motor. Cooling of the bi-metal allows the load current switch to re-close repeating the cycle. User adjustment of the cam varies the bias on the snap spring and thus the re-open point of the switch with respect to the cycle, thereby varying the ratio of "on" to "off" time of the load current. The heat motor sub-assembly including the base with the load connecting terminal, the U-shaped bi-metal, the heater and the moveable contact arm and heater connecting chip is pre-fabricated and installed in the controller housing as a unit.
REFERENCES:
patent: 5021762 (1991-06-01), Hetrick
patent: 5191310 (1993-03-01), Obermann et al.
patent: 5696479 (1997-12-01), Oughton et al.
Schamberger Stephen
Sehlhorst Scott B.
Detweiler Sean D.
Martin Terrence
Morris Jules Jay
Picard Leo P.
Vortman Anatoly
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