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US 4,510,765 AGranted
Control unit for refrigerators or freezers
AssigneeRanco Incorporated
InventorGuglielmo Rossi
Life of this patent
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AssigneeRanco Incorporated
InventorGuglielmo Rossi
Estimating the term…
A refrigerator or freezer of the type having an electrical defrost heater associated with its evaporator has a control unit including a switch device with a first pair of contacts (16, 17) controlling the cyclic cutting-in and cutting-out of a compressor motor and a second pair of contacts (16, 18), sharing a common movable contact (16) with the first pair, controlling the periodic energization of the defrost heater. Closure of the second pair of contacts is normally obstructed by a stop member (22) which is movable by a ratchet mechanism (24, 26) or other means responsive to a predetermined number of switching cycles of the compressor motor to a defrost position in which a notch (23) in the stop member (22) permits movement of the movable contact to close the second pair of contacts (16, 18) and energize the defrost heater.
A control unit for a refrigerator or freezer of the type including an evaporator, a compressor having a drive motor, and an electrical defrost heater associated with the evaporator, the said control unit including a switch device having a first pair of contacts controlling the cyclic cutting-in and cutting-out of the compressor drive motor, wherein the switch device has a second pair of contacts and a movable contact common to the first and second pair of contacts, the second pair of contacts controlling the periodic energisation of the defrost heater, a stop member associated with the second pair of contacts and normally obstructing closure thereof, actuator means acting on the stop member, said actuator means being responsive to a predetermined number of switching cycles of the compressor motor to move the stop member to a defrost position in which it permits movement of said movable contact to close the second pair of contacts and thereby energise the defrost heater, first operating means acting upon the common movable contact to open and close the first pair of contacts and to close the second pair of contacts, said first operating means being responsive to an ambient temperature in the apparatus, and second operating means for effecting movement of said movable contact in a sense to open the second pair of contacts to terminate energisation of the defrost heater, said second operating means being responsive to the evaporator temperature.
A control unit for a refrigerator or freezer of the type including an evaporator, a compressor having a drive motor, and an electrical defrost heater associated with the evaporator, the said control unit including a switch device having a first pair of contacts controlling the cyclic cutting-in and cutting-out of the compressor drive motor, a second pair of contacts controlling the energisation of the defrost heater, a movable contact common to the first and second pair of contacts, and temperature responsive means acting upon the movable contact, a rotatable stop member associated with the movable contact and normally obstructing closure of the second pair of contacts, the stop member having a defrost angular position in which it permits closure of said second pair of contacts, a ratchet mechanism for effecting angular movement of the stop member and actuator means acting upon the ratchet mechanism to advance the stop member by a predetermined pitch upon each operation of the actuator means, wherein the improvements consist in that the actuator means of the ratchet mechanism are mechanically independent of the movable contact and are energised under control of the first pair of contacts to advance the stop member by one pitch, and the stop member is normally interposed between the second pair of contacts and has a notch through which the movable contact passes to close the second pair of contacts when the stop member is in its defrost angular position.
A control unit for a refrigerator or freezer of the type including an evaporator, a compressor having a drive motor, and an electrically controlled defrosting means for effecting heating of the evaporator, the said control unit including a switch device having a first pair of contacts controlling the cyclic cutting-in and cutting-out of the compressor drive motor, a second pair of contacts controlling the periodic operation of said defrosting means, a movable contact common to the first and second pair of contacts, a stop member associated with said second pair of contacts and normally obstructing closure thereof, actuator means acting on the stop member to move the stop member to a defrost Position in which the stop member enables movement of said movable contact to close the second pair of contacts and thereby initiate operation of the defrosting means, first operating means acting on the common movable contact to open and close the first pair of contacts and to close the second pair of contacts, said first operating means being responsive to an ambient temperature in the apparatus, and second operating means for effecting movement of said movable contact in a sense to open the second pair of contacts to terminate operation of the defrosting means, said second operating means being responsive to the evaporator temperature.
Dependencies are inferred from the claim text.