Dual evaporator, dual fan refrigerator with independent temperature controls

Abstract: A refrigerator apparatus is provided having a cabinet with a freezer compartment (31) and a fresh food compartment (41). The compartments define two passageways allowing air circulation therebetween. A refrigerator system is included having a compressor (15,17), a condenser (21), an expansion valve (11,23), an evaporator (13) situated in the freezer compartment. The refrigerator system elements are connected in series in a closed loop, in a refrigerant flow relationship. A first fan (37) is situated in the freezer compartment (31) for providing air flow over the evaporator (13). A second fan (87) is situated in one of the two passageways for providing air circulation between the two compartments. A first thermostatic controller (51) situated in the freezer compartment (31) for maintaining a desired temperature in the freezer compartment (31) by causing the compressor (15,17) and the first fan (37) to operate. A second thermostatic controller (53) situated in the fresh food compartment (41) for maintaining a desired temperature in the fresh food compartment (41) by causing operation of the second fan (87) circulating air between the compartments thereby cooling the fresh food compartment (41).

Description: Background of the Invention The present invention relates to a refrigerator apparatus as defined in the preamble of claim 1. Such an apparatus is known, for example, from US-A-3 359 751. The presently used refrigeration cycle in household refrigerators is the simple vapor compression type using a single evaporator. Relative cooling rates for the freezer and the fresh food compartments are controlled by the user. A user adjusted control, sets the fixed fraction of the total cold air flow provided by the single evaporator and fan which is to reach the two refrigerator compartments. When the temperature of the fresh food compartment rises above a preset level, the compressor operates allowing the evaporator to supply cold air. Since the fraction of cold air provided to the fresh food and freezer compartments does not vary once set, control of freezer temperature is imperfect and freezer air temperatures vary considerably. Changes in the ambient temperature, time defrosts of the freezer compartment, and changes of incidental thermal loads (door opening frequency and duration) requires time varying changes in the fraction of cold air delivered to both compartments to properly control the temperature in both compartments. In a refrigeration cycle having dual evaporators such as the one shown in copending application EP-A-0 374 688 (which is comprised in the state of the art in accordance with Article 54(3) EPC), distinct cooling rates are provided by each evaporator during steady state operation. One evaporator operates at a temperature of approximately -23°C (-10°F) and the other at approximately -4°C (25°F) to provide cold air to the freezer and fresh food compartments, respectively. The cooling rates of the two evaporators depend entirely on heat exchanger and compressor designs, choice of refrigerant, ambient temperature, refrigerator cabinet thermal conductance and thermal loads other than conduction to the ambient. To provide separate and distinct narrow temperature ranges of operation in each of a refrigerators two compartments, provisions must be made to adjust the relative cooling rates of the two evaporators in response to changing ambient temperatures and incidental thermal loads. It is an object of the present invention to provide a control for regulating the cooling rates of a refrigerator equipped with a dual evaporator refrigerator system. Summary of the Invention A refrigerator apparatus is provided having a cabinet with a freezer compartment and a fresh food compartment. The compartments define two passageways allowing air circulation therebetween. A first evaporator is situated in the freezer compartment and a compressor is connected to the evaporator. A first fan is situated in the freezer compartment for providing air flow over the evaporator. A second fan is situated in one of the two passageways for providing air circulation between the compartments. A first thermostatic controller is situated in the freezer compartment for maintaining a desired temperature in the freezer compartment by causing the compressor and the first fan to operate. A second thermostatic controller is situated in the fresh food compartment for maintaining a desired temperature in the fresh food compartment by causing operation of the second fan independently of said first thermostatic controller. A second evaporator is situated in the fresh food compartment and is connected to the compressor. Brief Description of the Drawing The subject matter which is regarded as the invention is defined in claim 1. The invention itself, however, both as to its organization and its method of practice, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawing, in which the single figure is a schematic representation of the interior of the fresh food and freezer compartments of a refrigerator showing a control for controlling the relative cooling of the freezer and fresh food compartments. Detailed Description of the Invention Referring now to the single Figure, a refrigerator having a separate evaporator 25 in the fresh food compartment 31 and a separate evaporator 13 in the freezer compartment 31 is shown. The thermostatic controller 51 in the freezer compartment is connected to the motor controller of an hermetically sealed compressor (not shown) and to fans 37 and 47 in the freezer and fresh food compartments, respectively. The thermostatic controller 53 is connected to a fan 87 located in one of the two passageways interconnecting the fresh food and freezer compartments. Fan 87 can comprise a low energy consumption fan such as a piezoelectric fan. In operation, when thermostatic controller 51 detects the temperature in the freezer has risen above the user selected set point, the compressor (not shown) operates, providing cooled refrigerant in the two evaporators 13 and 25. Fans 37 and 47 circulate air over the evaporators 13 and 25. When the fresh food compartment thermostatic controller 53 detects that the temperature in the fresh food compartment is above the desired user selected temperature fan 87 operates circulating air between the compartments cooling the fresh food compartment while warming the freezer compartment. Fan 87 operates whenever the fresh food compartment is above a preselected temperature, whether or not the compressor is operating. The foregoing has described a control for regulating the cooling rates of a refrigerator equipped with a dual evaporator refrigerator system.

Claims: A refrigerator apparatus comprising: a cabinet (33) having a freezer compartment (31) and a fresh food compartment (41), said compartments defining two passageways allowing air circulation therebetween; a first evaporator (13) situated in said freezer compartment and a compressor (15) connected to said evaporator; a first fan (37) situated in said freezer compartment for providing air flow over said evaporator; a second fan (87) situated in one of said two passageways for providing air circulation between said compartments; a first thermostatic controller (51) situated in said freezer compartment for maintaining a desired temperature in said freezer compartment by causing operation of said compressor and said first fan; a second thermostatic controller (53) situated in said fresh food compartment for maintaining a desired temperature in said fresh food compartment by causing operation of said second fan independently of said first thermostatic controller; characterized by: a second evaporator ( 25) situated in said fresh food compartment (41); said compressor (15) also being connected to said second evaporator (25). The refrigerator apparatus of claim 1 further comprising: a third fan (47) situated in said fresh food compartment (41) for providing air flow over said second evaporator (25); said first thermostatic controller (51) also being connected to said third fan (47).

Inventors: BESSLER WARREN FRANK, JASTER HEINZ, BESSLER, WARREN FRANK, JASTER, HEINZ
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 1989
Main classification: F25D17
IPC codes: F25D17, F25B1, F25D11, F25B5, F25D29