Refrigeration – Automatic control – Of external fluid or means
Reexamination Certificate
1999-11-16
2001-03-06
McDermott, Corrine (Department: 3744)
Refrigeration
Automatic control
Of external fluid or means
C062S177000
Reexamination Certificate
active
06196011
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to refrigeration systems and more specifically to refrigeration systems with independent compartment temperature control.
Household refrigerators typically operate on a simple vapor compression cycle. Such a cycle typically includes a compressor, a condenser, an expansion device and an evaporator connected in series and charged with a refrigerant. The evaporator is a specific type of heat exchanger that transfers heat from air passing over the evaporator to refrigerant flowing through the evaporator, thereby causing the refrigerant to vaporize. The cooled air is then used to refrigerate one or more freezer or fresh food compartments.
Household refrigerators are expected to operate over a range of ambient temperatures, typically from about 55° F. to about 90° F. System users are typically supplied control knobs to adjust Fresh Food and Freezer compartment temperatures. At each combined setting of the control knobs, there is a target set of Fresh Food and Freezer temperatures that an ideal refrigerator should achieve, independent of ambient conditions. Different hardware and control strategies attempt to approximate this ideal performance matrix.
Typically a control device is used to regulate airflow to the fresh food compartment to account for the changing load split between freezer and fresh food sections. During high ambient temperature and frequent fresh food access, more airflow to the fresh food section is required to maintain target temperatures. Manual damper air control cannot automatically compensate for changing loads and is prone to customer misadjustment. Motorized damper airflow modulation, powered by a system controller, is prone to malfunction (i.e. freeze up) and may cause adverse temperature gradients during low ambient operation.
Accordingly, there is a need in the art for an improved refrigeration system for achieving ideal performance temperatures of fresh food and freezer compartments.
SUMMARY OF THE INVENTION
A refrigeration system is disposed within an outer cabinet having a freezer compartment and a fresh food compartment connected via a mullion opening. A compressor, a condenser, an expansion device and a freezer evaporator are connected in series to expand and condense a refrigerant to cool the compartments. A freezer compartment temperature sensor and a fresh food compartment temperature sensor are provided to sense compartment temperatures. A discrete speed evaporator fan directs cooling air throughout the freezer compartment and through the mullion opening to the fresh food compartment. A controller generates control signals to the discrete speed evaporator fan to operate at high speed if either the fresh food compartment or both the freezer and fresh food compartments demand cooling and to operate at low speed if the freezer compartment alone demands cooling.
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patent: 5255530 (1993-10-01), Janke
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patent: 5471849 (1995-12-01), Bessler
patent: 5531078 (1996-07-01), Day et al.
patent: 5586445 (1996-12-01), Bessler
patent: 5669222 (1997-09-01), Jaster et al.
patent: 5899083 (1999-05-01), Peterson et al.
General Electric Company
McDermott Corrine
Norman Marc
Patnode Patrick K.
Snyder Marvin
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