Refrigerator and method for controlling the same

A refrigerant recovery operation method for use in a refrigerator in which a freezing chamber and a refrigerating chamber are independently cooled is disclosed. The refrigerator and the method for controlling the same provide for performing the refrigerant recovery operation not only when the compressor starts operation but also before the compressor stops operation. The refrigerator increases the refrigerant recovery amount within a predetermined pressure range in which the compressor can operate, and controls the refrigerant recovery operation time according to the outdoor air temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2015-0094595, filed on Jul. 2, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Embodiments of the present disclosure relate to a refrigerant recovery operation method for use in a refrigerator in which a freezing chamber and a refrigerating chamber are independently cooled.

2. Description of the Related Art

Generally, refrigerators are apparatuses to which a general refrigerating cycle to circulate a refrigerant thereinto is applied so as to supply cold air, generated by absorbing surrounding heat when the refrigerant in a liquid state is evaporated, to storage chambers, such as freezing and refrigerating chambers, to store food in a fresh state for a long time. The freezing chamber is kept at a low temperature of about −20° C., and the refrigerating chamber is kept at a low temperature of about 3° C.

Among these refrigerators, a parallel cycle-type refrigerator in which an evaporator is separately installed in each of a freezing chamber and a refrigerating chamber and operations of the freezing chamber and the refrigerating chamber are independently controlled using a 3-way valve has been disclosed.

The parallel cycle-type refrigerator achieves the operation of the refrigerating chamber independently of the operation of the freezing chamber and thus maintains high evaporation temperature of the refrigerating chamber, thereby improving energy efficiency during the operation of the refrigerating chamber. However, in the parallel cycle-type refrigerator, a certain amount of refrigerant moves to the freezing chamber evaporator and is trapped in the freezing chamber evaporator, and thereby the refrigerant becomes insufficient during the next operation of the refrigerating chamber.

Therefore, in the conventional parallel cycle-type refrigerator, after the operations of the refrigerating chamber and the freezing chamber, a refrigerant recovery operation (a pump down operation), in which the refrigerant distributed at a low-pressure part (the freezing chamber evaporator and the refrigerating chamber evaporator) is transferred to a high-pressure part (a condenser) by operating the compressor under the condition that passages of the 3-way valve in two directions, i.e., passages of the 3-way valves at the sides of the refrigerating chamber and the freezing chamber are closed, is performed, and then the operation of the compressor is completed.

Conventionally, the refrigerant recovery operation is performed only once when the compressor starts operation or just before the compressor stops operation. Therefore, the time for the refrigerant recovery operation must be sufficiently guaranteed so as to recover refrigerant kept at a low-pressure part. However, since suction pressure of the compressor is reduced in proportion to the increasing refrigerant recovery operation time, energy needed to drive the compressor increases and pressure of the low-pressure part (a freezing chamber evaporator and a refrigerating chamber evaporator) is rapidly reduced down to a vacuum. If a temperature of each evaporator is rapidly reduced to an extremely low temperature due to abrupt pressure reduction and refrigerant evaporation, refrigerant having an extremely low temperature is introduced into the compressor, such that the compressor temperature is reduced and liquid compression occurs, resulting in reduction of reliability of the compressor. As a result, there is a need to increase the refrigerant recovery amount within a predetermined pressure range in which the compressor can operate.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a refrigerator and a method for controlling the same in which a refrigerant recovery operation is performed not only when the compressor starts operation but also before the compressor stops operation, such that a refrigerant recovery operation time and reliability of the compressor are guaranteed.

It is another aspect of the present disclosure to provide a refrigerator and a method for controlling the same in which a refrigerant recovery operation time is variably controlled according to an outdoor air temperature, resulting in improvement of energy efficiency.

In accordance with an aspect of the present invention, a refrigerator includes: a compressor; a condenser configured to condense refrigerant compressed by the compressor; a freezing chamber evaporator and a refrigerating chamber evaporator connected in parallel to an outlet of the condenser; a flow passage switching valve configured to switch a flow passage of the refrigerant in a manner that the refrigerant flows toward any one of the freezing chamber evaporator and the refrigerating chamber evaporator; and a controller configured to control the flow passage switching valve in a manner that a refrigerant recovery operation is performed not only when the compressor starts operation but also before the compressor stops operation.

The refrigerator may further include: a temperature sensor configured to detect an outdoor air temperature, wherein the controller variably controls a refrigerant recovery operation time according to the detected outdoor air temperature.

The controller may increase the refrigerant recovery operation time in proportion to the increasing outdoor air temperature.

The refrigerator may further include: a check valve arranged at an outlet of the freezing chamber evaporator, wherein the check valve prevents the refrigerant from flowing to the freezing chamber evaporator during the refrigerant recovery operation.

The flow passage switching valve may be a 3-way valve, which is connected to a pipe of an outlet of the condenser and also connected to pipes of inlets of the freezing chamber evaporator and the refrigerating chamber evaporator.

In accordance with another aspect of the present invention, a refrigerator includes: a first storage chamber controlled at a first target temperature; a second storage chamber spatially separated from the first storage chamber, and controlled at a second target temperature higher than the first target temperature; a first evaporator and a second evaporator respectively installed in the first storage chamber and the second storage chamber in a manner that the first storage chamber and the second storage chamber are independently cooled; a compressor connected to the first evaporator and the second evaporator so as to compress refrigerant; and a controller configured to perform a refrigerant recovery operation in which refrigerant remaining in any one of the first evaporator and the second evaporator is recovered, not only when the compressor starts operation but also before the compressor stops operation.

The refrigerator may further include: a check valve arranged at any one of outlets of the first evaporator and the second evaporator.

The refrigerator may further include: a flow passage switching valve configured to switch a flow passage of the refrigerant in a manner that the refrigerant flows toward any one of the first evaporator and the second evaporator; and wherein the refrigerant recovery operation moves the refrigerant remaining in a low-pressure part toward a high-pressure part by operating the compressor on the condition that all directions of the flow passage switching valve are closed.

In accordance with an aspect of the present invention, a method for controlling a refrigerator which includes a compressor and a freezing chamber evaporator and a refrigerating chamber evaporator connected in parallel to an outlet of the compressor includes: determining whether a start time of the compressor is achieved; if the start time of the compressor is achieved, performing a first refrigerant recovery operation in which refrigerant remaining in the freezing chamber evaporator is recovered; independently cooling a freezing chamber and a refrigerating chamber upon completion of the first refrigerant recovery operation; determining whether an OFF condition of the compressor is achieved while the freezing chamber and the refrigerating chamber are independently cooled; if the OFF condition of the compressor is achieved, performing a second refrigerant recovery operation in which refrigerant remaining in the freezing chamber evaporator is recovered; and stopping the compressor upon completion of the second refrigerant recovery operation.

The method may further include: detecting an outdoor air temperature; and changing an operation time of the first refrigerant recovery operation and an operation time of the second refrigerant recovery operation according to the detected outdoor air temperature.

The operation time of the first refrigerant recovery operation may be identical to the operation time of the second refrigerant recovery operation.

The operation time of the first refrigerant recovery operation may be different from the operation time of the second refrigerant recovery operation.

The first refrigerant recovery operation and the second refrigerant recovery operation may operate the compressor on the condition that supply of the refrigerant flowing to the freezing chamber evaporator and the refrigerating chamber evaporator is prevented, such that the refrigerant remaining in the freezing chamber evaporator moves to a high-pressure part.

The start time of the compressor may be identical to a time point at which the compressor starts operation when indoor air temperatures of the freezing chamber and the refrigerating chamber are higher than respective target temperatures by a predetermined temperature or higher.

The OFF condition of the compressor may indicate a time point at which the compressor stops operation after indoor air temperature of each of the freezing chamber and the refrigerating chamber reaches a target temperature.

DETAILED DESCRIPTION

Refrigerators may be broadly classified into a side-by-side type refrigerator, a bottom freezer type refrigerator, and a top mount type refrigerator. In the side-by-side type refrigerator, the freezing chamber and the refrigerating chamber are arranged side by side. In the bottom freezer type refrigerator, the freezing chamber is arranged under the refrigerating chamber. In the top mount type refrigerator, the freezing chamber is arranged above the refrigerating chamber. Although the refrigerator according to embodiments is exemplarily implemented as the side-by-side type refrigerator for convenience of description and better understanding of the present disclosure, the scope or spirit of the present disclosure is not limited thereto, and the embodiments can also be applied to the bottom freezer type refrigerator, the top mount type refrigerator, and a combination thereof.

In addition, the embodiments of the present disclosure can also be applied not only to a refrigerator in which an ice making chamber is provided at the refrigerating chamber but also to the other refrigerator in which the ice making chamber is provided at the freezing chamber, without departing from the scope or spirit of the present disclosure.

FIG. 1is a view illustrating an external appearance of a refrigerator according to one embodiment of the present invention.FIG. 2is a view illustrating an internal structure of the refrigerator according to the embodiment of the present invention.

Referring toFIGS. 1 and 2, the refrigerator1according to an embodiment may include a box-shaped main body10forming the external appearance thereof, a plurality of storage chambers (12,14) formed in the main body10so as to store foods therein, and doors (13,15) rotatably coupled to the main body10so as to open or close the plurality of storage chambers (12,14).

The storage chambers (12,14) are divided into a right compartment and a left compartment by a partition, such that the right compartment is used as a refrigerating chamber14and the left compartment is used as the freezing chamber12. The freezing chamber12and the refrigerating chamber14are configured to form independent storage chambers, and storage temperatures of the freezing chamber12and the refrigerating chamber14may be independently controlled according to the amount of cold air supplied to the freezing chamber12and the refrigerating chamber14. The freezing chamber12may be controlled at a first target temperature (about −20° C.), and the refrigerating chamber14may be controlled at a second target temperature (about +3° C.).

In addition, the freezing chamber12and the refrigerating chamber14are each divided into a plurality of spaces by a plurality of shelves, such that foods can be stored in each space. A freezing chamber evaporator32for cooling the freezing chamber may be installed at a back surface of the freezing chamber12, and a refrigerating chamber evaporator34for cooling the refrigerating chamber14may be installed at a back surface of the refrigerating chamber14.

FIG. 3is a schematic view illustrating a parallel cycle of the refrigerator according to the embodiment of the present invention.

Referring toFIG. 3, a parallel cycle of the refrigerator1according to the embodiment of the present disclosure may include a compressor20, a condenser22, a hot pipe24, a flow passage switching valve26, freezing and refrigerating chamber expansion units (28,30), freezing and refrigerating chamber evaporators (32,34), and a check valve36.

For this, the compressor20may forcibly suction the refrigerant, and compress the suctioned refrigerant to produce high-temperature and high-pressure gas. Suctioning of the refrigerant may be carried out using rotational force of an embedded motor. By the refrigerant suctioning force of the compressor20, the refrigerant may circulate in the cooling cycle of the refrigerator1. Therefore, the refrigerant circulation amount and the refrigerant circulation speed may be determined according to a driving degree of the compressor20, and the cooling efficiency of the refrigerator1may also be determined.

In addition, the compressor20may include an inlet through which refrigerant is introduced, a flow space in which introduced refrigerant flows, a motor rotating in the flow space and constituent elements associated with the motor, and an outlet through which compressed refrigerant is discharged.

Refrigerant applied to the compressor20may be chlorofluorocarbon (CFC) refrigerant, hydrochlorofluorocarbon (HCFC) refrigerant, hydroflurocarbon (HFC) refrigerant, or the like. However, the scope or spirit of the refrigerant according to the present disclosure is not limited thereto, and various kinds of materials capable of being selected by a system designer may also be used as the refrigerant.

The compressor20according to the present disclosure may be applied to an inverter compressor, a volumetric compressor, a dynamic compressor, or the like.

The high-temperature and high-pressure gaseous refrigerant compressed by the compressor20may be transferred to the condenser22.

The condenser22may be connected to a discharge tube of a high-pressure part of the compressor20in a manner that high-temperature and high-pressure gaseous refrigerant compressed by the compressor20exchanges heat with ambient air, such that the high-temperature and high-pressure gaseous refrigerant is condensed into liquid refrigerant. In the condenser22, the refrigerant is liquefied to emit heat to the outside, such that a temperature of the refrigerant is reduced.

The hot pipe24may extend from the condenser22and may be coupled to an inlet of the flow passage switching valve26, and may prevent dew formation, caused by a difference in temperature between an inner space and an outer space by heat emission of the refrigerant flowing in the hot pipe24, from occurring at the front surface of the main body10.

The flow passage switching valve26may selectively switch a flow passage of the refrigerant having passed through the condenser22according to an operation mode (e.g., a freezing chamber operation mode or a refrigerating chamber operation mode), and may be implemented as a 3-way valve including one inlet and two outlets. The inlet may be connected to the hot pipe24, and the two outlets may be respectively connected to a freezing chamber expansion unit28and a refrigerating chamber expansion unit30, respectively. A freezing chamber side flow passage connected to the freezing chamber expansion unit28is hereinafter referred to as ‘F’ direction, and a refrigerating chamber side flow passage connected to the refrigerating chamber expansion unit30is hereinafter referred to as ‘R’ direction. The opening/closing operation of the freezing chamber side flow passage is hereinafter referred to as ON/OFF operation of the F direction, and the opening/closing operation of the refrigerating chamber side flow passage is hereinafter referred to as ON/OFF operation of the R direction.

The freezing chamber expansion unit28and the refrigerating chamber expansion unit30may expand normal-temperature and high-pressure liquid refrigerant condensed by the condenser22into 2-phase refrigerant in which low-temperature and low-pressure liquid and gas components are mixed. Each of the freezing chamber expansion unit28and the refrigerating chamber expansion unit30may be implemented as an expansion valve.

The expansion valve may include various kinds of valves, for example, a thermoelectric electronic expansion valve configured to use bimetal deformation, a thermostatic electronic expansion valve configured to use volumetric expansion caused by heating of inserted wax, a PWM-type electronic expansion valve configured to open or close a solenoid valve using a pulse signal, and a step-motor type electronic expansion valve configured to open or close the valve using a motor.

In addition, each of the freezing chamber expansion unit28and the refrigerating chamber expansion unit30may also be implemented as a capillary tube, instead of the expansion valve. The capillary tube may also be implemented as a slender tube, and the refrigerant passing through the capillary tube is decompressed and then applied to the freezing chamber evaporator32and the refrigerating chamber evaporator34.

The freezing chamber evaporator32may provide cold air by evaporating low-temperature and low-pressure liquid refrigerant expanded by the freezing chamber expansion unit28into a gaseous state. The refrigerating chamber evaporator34may provide cold air by evaporating low-temperature and low-pressure liquid refrigerant expanded by the refrigerating chamber expansion unit30into a gaseous state. The freezing chamber evaporator32and the refrigerating chamber evaporator34may operate according to the parallel cycle scheme in which the freezing chamber12and the refrigerating chamber14are independently operated using the flow passage switching valve26.

Pipes extending from the outlets of the freezing chamber evaporator32and the refrigerating chamber evaporator34are combined into one pipe, and the combined pipe is connected to the inlet of the compressor20.

A check valve36is installed at the outlet of the freezing chamber evaporator32, and prevents refrigerant from flowing to the freezing chamber evaporator32in the parallel cycle. Although the refrigerant is collected at a side of the condenser22by the refrigerant recovery operation, the refrigerant is re-introduced into the freezing chamber evaporator32prior to execution of a subsequent refrigerating chamber operation, such that the amount of necessary refrigerant is insufficient during the operation of the refrigerating chamber14. Therefore, the check valve36is installed at the outlet of the freezing chamber evaporator32, such that it can prevent the refrigerant from being re-introduced into the freezing chamber evaporator32.

In the refrigerator1according to one embodiment, the compressor20and the condenser22may be installed in a machine room (not shown) located under the main body10, the freezing chamber evaporator32may be installed at the rear part of the inside of the main body10corresponding to a back surface of the freezing chamber12, and the refrigerating chamber evaporator34may be installed at the rear part of the inside of the main body10corresponding to a back surface of the refrigerating chamber14, such that the freezing chamber12and the refrigerating chamber14can be independently cooled.

In the refrigerator1according to one embodiment, a condensing fan221, a freezing chamber fan321, and a refrigerating chamber fan341may be respectively installed in the vicinity of the condenser22, the freezing chamber evaporator32, and the refrigerating chamber evaporator34.

FIG. 4is a control block diagram of the refrigerator according to the embodiment of the present invention.

Referring toFIG. 4, the refrigerator1according to one embodiment may include the indoor air temperature sensor100, an outdoor air temperature sensor110, an input unit120, a controller130, a memory140, a drive unit150, and a display unit160.

The indoor air temperature sensor100included in the refrigerator1may detect indoor air temperatures of the freezing chamber12and the refrigerating chamber14, and may output the detected indoor air temperatures to the controller130. The detected indoor air temperatures may be used as data for determining the operation conditions (a simultaneous operation or an individual operation) of the freezing chamber12and the refrigerating chamber14.

In addition, the indoor air temperature sensor100may include at least one temperature sensor installed at arbitrary internal positions (e.g., the ceiling, bottom, or inner wall) of the freezing chamber12and the refrigerating chamber14so as to detect the indoor air temperatures of the freezing chamber12and the refrigerating chamber14.

The outdoor air temperature sensor110may detect a temperature (i.e., outdoor air temperature) of the surrounding area of the refrigerator1, and may transmit the detected outdoor air temperature to the controller130.

Each of the indoor air temperature sensor100and the outdoor air temperature sensor110may be implemented as a contact temperature sensor or a non-contact temperature sensor. In more detail, the temperature sensor may be implemented as any one of a resistance temperature detector (RTD) temperature sensor configured to use the change of metal resistance depending upon temperature variation, a thermistor temperature sensor configured to use the change of semiconductor resistance depending upon temperature variation, a thermocouple temperature sensor configured to use EMF (electromotive force) generated at both ends of a junction point of two types of metal lines each formed of a different material, and an IC temperature sensor configured to use any one of a voltage generated from both ends of a transistor having characteristics changed according to temperature, and current-voltage characteristics of a PN junction unit of the transistor. However, the scope or spirit of the temperature sensor according to the embodiment is not limited thereto, and various temperature detection machines may also be used by those skilled in the art without departing from the scope or spirit of the present disclosure.

The input unit120may input a control command of a user to the controller130. A plurality of buttons, for example, a mode selection button for controlling the operations of the freezing chamber12and the refrigerating chamber14and a temperature setting button for setting a temperature of each of the freezing chamber12and the refrigerating chamber14to a desired temperature, may be arranged on a control panel of the input unit120.

In addition, the input unit120may be implemented not only as the above-mentioned buttons, but also as a key, a knob, a switch, a touchpad, etc. The input unit120may include all kinds of devices configured to generate predetermined input data by various manipulations, for example, pushing, contacting, pressing, rotating, etc.

The controller130may serve as a processor for controlling overall operation of the refrigerator according to operation information entered by the input unit120, may determine the operation condition (e.g., simultaneous operation or individual operation) of the freezing chamber12and the refrigerating chamber14according to indoor air temperatures detected by the indoor air temperature sensors100respectively installed in the freezing chamber12and the refrigerating chamber14, and may control the freezing chamber12and the refrigerating chamber14according to the parallel cycle scheme in which the freezing chamber12and the refrigerating chamber14are independently cooled.

In addition, the controller130may divide the refrigerant recovery operation into two sub-recovery operations, such that the two sub-recovery operations may be respectively carried out when the compressor20starts operation or just before the compressor20stops operation. Since the refrigerant recovery operation is achieved by closing all the inlets of the freezing chamber evaporator32and the refrigerating chamber evaporator34, and operating the compressor20such that the refrigerant remaining in the low-pressure part (e.g., the freezing chamber evaporator and the refrigerating chamber evaporator) is collected into the high-pressure part (e.g., the condenser), a sufficiently long refrigerant recovery operation time needs to be guaranteed.

If the refrigerant recovery operation time is short, the amount of refrigerant recovered to the refrigerating chamber14becomes insufficient, such that energy consumption may increase and the cooling capacity of the refrigerating chamber14may decrease.

In contrast, if the refrigerant recovery operation time is long, the suction pressure of the compressor20needs to be excessively reduced for the remaining refrigerant recovery, and the compressor20operates at a low pressure, such that the compressor20may be damaged or broken.

Therefore, according to the parallel cycle scheme in which the refrigerating chamber14and the freezing chamber12are independently cooled, a sufficiently long refrigerant recovery operation time is guaranteed and the refrigerant recovery amount increases, such that refrigerant shortage may be prevented from occurring in the operation of the refrigerating chamber14and the compressor20may also be prevented from dropping to a low pressure, resulting in acquisition of high reliability of the compressor20.

For this, the embodiment of the present disclosure may divide the refrigerant recovery operation into two refrigerant recovery operation actions to be respectively performed when the compressor20starts operation and just before the compressor20stops operation.

The memory140may store setting information (e.g., control data for controlling the refrigerator1, reference data used in the control process of the refrigerator1, operation data generated during a predetermined operation of the refrigerator1, and setting data entered by the input unit120in a manner that the refrigerator1performs a given operation), use information of the refrigerator1(e.g., the number of specific operations executed by the refrigerator1and model information of the refrigerator1), and malfunction information of the refrigerator1(e.g., the reason or position of a faulty operation of the refrigerator1).

In addition, the memory140may store temperature control values based on the operation conditions (decided by the controller130) of the freezing chamber12and the refrigerating chamber14, and may store a control factor related to the parallel cycle operation in which the refrigerant recovery operation is carried out. For example, the memory140may store a detection period of the indoor air temperature sensor100, data related to the operation time or operation RPM of the compressor20according to the detection result of the indoor air temperature sensor100, a control program for controlling the refrigerator1, and other programs (e.g., dedicated application initially supplied from the manufacturing company or universal applications downloaded from the external part).

The memory140may be implemented as a non-volatile memory device such as a read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), or flash memory, a volatile memory device such as a random access memory (RAM), or a storage unit such as a hard disk or an optical disc. However, the memory140is not limited thereto and may have other forms known in the art.

The drive unit150may drive the compressor20, the flow passage switching valve26, the condensing fan221, the freezing chamber fan321, and the refrigerating chamber fan341, etc. associated with the operations of the refrigerator1according to a drive control signal of the controller130.

The display unit160may display the operation state of the refrigerator1according to a display control signal of the controller130, and may display a user manipulation state by recognizing the operation information entered through the input unit120.

In addition, assuming that the display unit160is implemented as an LCD user interface (UI) for text display, the operation state of the refrigerator1is displayed as text, such that the user can conduct appropriate measures.

Assuming that the display unit160is implemented as an LED UI, the display unit160can allow the user to recognize an abnormal state of the refrigerator1using lighting or blinking or using a difference in duration of the display unit160.

The operations and effects of a refrigerator and a method for controlling the same according to the embodiment of the present disclosure will hereinafter be described with reference to the attached drawings.

A method for cooling internal spaces of the freezing chamber12and the refrigerating chamber14according to the order of cooling of the refrigerating chamber14→cooling of the freezing chamber12→stopping of the compressor20in the parallel cycle of the refrigerator1will hereinafter be described with reference toFIGS. 5 and 6.

FIG. 5is a flowchart illustrating a first control algorithm needed for the refrigerant recovery operation of the refrigerator according to an embodiment of the present disclosure.FIG. 6is a timing diagram illustrating refrigerant recovery control time points shown inFIG. 5.

Referring toFIGS. 5 and 6, the indoor air temperature sensor100may detect a temperature of indoor air of each of the freezing chamber12and the refrigerating chamber14, and may transmit the detected indoor air temperatures to the controller130.

Therefore, the controller130may compare the indoor air temperatures (detected by the indoor air temperature sensors100) of the freezing chamber12and the refrigerating chamber14with user setting temperatures, and may determine whether the start time of the compressor20is achieved (S200).

If the indoor air temperature of the freezing chamber12or the refrigerating chamber14is higher than the user setting temperature by a predetermined temperature or higher, internal load of the freezing chamber12or the refrigerating chamber14is calculated according to a difference in temperature, and the compressor20may then start operation at a time point corresponding to the start time of the compressor20.

If it is determined in operation200that the start time of the compressor20is achieved, the controller130may output a drive control signal to the compressor20through the drive unit150, such that the compressor20starts operation (S202).

Subsequently, the controller130may perform a first refrigerant recovery operation to recover the refrigerant remaining in the freezing chamber evaporator32into the condenser22at the start time of the compressor20(S204).

The refrigerant recovery operation starts operation of the compressor20under the condition that it stops providing the refrigerant to both the freezing chamber evaporator32and the refrigerating chamber evaporator34by closing both directions (F direction, R direction) of the flow passage switching valve26, such that the refrigerant remaining in the freezing chamber evaporator32moves to the condenser22. As a result, shortage of the refrigerant needed to cool the refrigerating chamber14in a subsequent process is prevented through the refrigerant recovery operation.

After the refrigerant remaining in the freezing chamber evaporator32moves to the condenser22through the first refrigerant recovery operation performed at the start time of the compressor20, the controller130may switch on the flow passage switching valve26in the R direction (i.e., the refrigerating chamber direction) shown inFIG. 6so as to cool the refrigerating chamber14.

If the flow passage switching valve26is switched on in the R direction (i.e., the refrigerating chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→refrigerating chamber expansion unit30→refrigerating chamber evaporator34→compressor20in the refrigerating chamber operation mode.

Therefore, high-temperature and high-pressure gaseous refrigerant discharged from the compressor20is introduced into the condenser22so that it is condensed into high-pressure liquid refrigerant, and the high-pressure liquid refrigerant flows in the flow passage switching valve26after passing through the hot pipe24.

In this case, since the flow passage switching valve26opens only the refrigerating chamber side flow passage in the R-direction, the refrigerant applied to the flow passage switching valve26is introduced into the refrigerating chamber evaporator34through the refrigerating chamber expansion unit30so as to cool the refrigerating chamber14, and returns to the compressor20, thereby carrying out the cooling operation of the refrigerating chamber14(S206).

If the refrigerating chamber14is cooled after the first refrigerant recovery operation is performed at the start time of the compressor20, shortage of the refrigerant is prevented, resulting in an increase of the cooling efficiency of the refrigerating chamber14.

After the indoor air temperature of the refrigerating chamber14reaches the setting temperature, the controller130may switch on the flow passage switching valve26in the F direction (i.e., the freezing chamber direction) shown inFIG. 6so as to cool the freezing chamber12.

If the flow passage switching valve26is switched on in the F direction (i.e., the freezing chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→freezing chamber expansion unit28→freezing chamber evaporator32→compressor20in the freezing chamber operation mode.

Therefore, high-temperature and high-pressure gaseous refrigerant discharged from the compressor20is introduced into the condenser22so that it is condensed into high-pressure liquid refrigerant, and the high-pressure liquid refrigerant flows in the flow passage switching valve26after passing through the hot pipe24.

In this case, since the flow passage switching valve26opens only the freezing chamber side flow passage in the F-direction, the refrigerant applied to the flow passage switching valve26is introduced into the freezing chamber evaporator32through the freezing chamber expansion unit28so as to cool the freezing chamber12, and returns to the compressor20, thereby carrying out the cooling operation of the freezing chamber12(S208).

As described above, after the freezing chamber12and the refrigerating chamber14are independently cooled, the controller130may determine whether the compressor20is in an OFF condition (S210).

The OFF condition of the compressor20may indicate a time point at which the compressor20stops operation after the internal temperatures of the refrigerating chamber14and the freezing chamber12reach the respective setting temperatures.

If the compressor20is in the OFF condition in operation210, the controller130may perform a second refrigerant recovery operation just before the compressor20stops operation such that the refrigerant remaining in the freezing chamber evaporator32is recovered into the condenser22(S212).

Since the second refrigerant recovery operation is carried out just before the compressor20stops operation, the refrigerant recovered from the freezing chamber evaporator32can be stored in the high-pressure part (i.e., a compressor cylinder and the condenser). The refrigerant stored in the high-pressure part is switched to the refrigerating chamber14along with the other refrigerant recovered by the first refrigerant recovery operation performed at the start time of the compressor20, such that the operation efficiency of the refrigerating chamber14can be maximized.

As described above, the first refrigerant recovery operation and the second refrigerant recovery operation may be respectively performed when the compressor20starts operation and before the compressor20stops operation, such that the refrigerant recovery operation time can be sufficiently guaranteed and the compressor20is prevented from dropping to a low pressure, resulting in high reliability of the compressor20. A detailed description thereof will hereinafter be given with reference toFIG. 7.

FIG. 7is a graph illustrating a compressor pressure status changing during the refrigerant recovery operation of the refrigerator according to an embodiment of the present disclosure.

Referring toFIG. 7, according to a conventional parallel cycle, the refrigerant recovery operation is performed only once when the compressor20starts operation or before the compressor20stops operation. In order to recover the refrigerant remaining in the low-pressure part, the refrigerant recovery operation time may be carried out for about 120 seconds. If the refrigerant recovery operation time is carried out for 120 seconds, pressure of the low-pressure part of the compressor20is abruptly reduced so that it can be recognized that the refrigerant recovery amount is gradually reduced as shown inFIG. 7.

Therefore, according to the parallel cycle of the present disclosure, the refrigerant recovery operation is divided into two sub-recovery operations not only when the compressor20starts operation but also before the compressor20stops operation, such that the refrigerant recovery operation may be performed two times not only when the compressor20starts operation but also before the compressor20stops operation. Assuming that the refrigerant recovery operation is divided into two sub-recovery operations, pressure of the low-pressure part of the compressor20may increase when the compressor20stops operation as shown inFIG. 7. As a result, pressure reduction of the low-pressure part of the compressor20is decreased so that it can be recognized that the refrigerant recovery amount increases.

As described above, assuming that the refrigerant recovery operation is divided into two sub-recovery operations, instead of being performed once for a long period of time, pressure reduction of the low-pressure part of the compressor20is achieved within the operable available pressure of the compressor20as shown inFIG. 7, such that reliability of the compressor20can be guaranteed and the refrigerant recovery amount can increase.

Generally, although the embodiment has exemplarily disclosed that the refrigerant recovery operation time (t) may be carried out for about 120 seconds, the scope or spirit of the refrigerant recovery operation time (t) is not limited thereto, and the refrigerant recovery operation time (t) can also be changed according to the capacity or design structure of the refrigerator1as necessary.

After the refrigerant recovered from the freezing chamber evaporator32is stored in the high-pressure part through the second refrigerant recovery operation performed just before the compressor20stops operation, the controller130may stop the compressor20through the drive unit150(S214), and may then stop the parallel cycle.

Subsequently, a method for cooling internal spaces of the freezing chamber12and the refrigerating chamber14according to the order of cooling of the freezing chamber12cooling of the refrigerating chamber14stopping of the compressor20in the parallel cycle of the refrigerator1will hereinafter be described with reference toFIGS. 8 and 9.

FIG. 8is a flowchart illustrating a second control algorithm needed for the refrigerant recovery operation of the refrigerator according to an embodiment of the present disclosure.FIG. 9is a timing diagram illustrating refrigerant recovery control time points shown inFIG. 8. Parts ofFIGS. 8 and 9identical to those ofFIGS. 5 and 6are denoted by the same numerals and the same names, and a detailed description thereof will not be given.

Referring toFIGS. 8 and 9, the indoor air temperature sensor100may detect a temperature of indoor air of each of the freezing chamber12and the refrigerating chamber14, and may transmit the detected indoor air temperatures to the controller130.

Therefore, the controller130may compare the indoor air temperatures (detected by the indoor air temperature sensors100) of the freezing chamber12and the refrigerating chamber14with setting temperatures, and may determine whether the start time of the compressor20is achieved (S300).

If it is determined in operation300that the start time of the compressor20is achieved, the controller130may start operation through the drive unit150(S302).

Subsequently, the controller130may perform a first refrigerant recovery operation to recover the refrigerant remaining in the freezing chamber evaporator32to the side of the condenser22at the start time of the compressor20(S304).

After the refrigerant remaining in the freezing chamber evaporator32moves to the side of the condenser22through the first refrigerant recovery operation performed at the start time of the compressor20, the controller130may switch on the flow passage switching valve26in the F direction (i.e., the freezing chamber direction) shown inFIG. 9so as to cool the freezing chamber12.

If the flow passage switching valve26is switched on in the F direction (i.e., the freezing chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→freezing chamber expansion unit28→freezing chamber evaporator32→compressor20in the freezing chamber operation mode, thereby performing the cooling operation of the freezing chamber12(S306).

After the indoor air temperature of the freezing chamber12reaches the setting temperature, the controller130may switch on the flow passage switching valve26in the R direction (i.e., the refrigerating chamber direction) shown inFIG. 9so as to cool the refrigerating chamber14.

If the flow passage switching valve26is switched on in the R direction (i.e., the refrigerating chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→refrigerating chamber expansion unit30→refrigerating chamber evaporator34→compressor20in the refrigerating chamber operation mode, thereby performing the cooling operation of the refrigerating chamber14(S308).

If the refrigerating chamber14is cooled after the first refrigerant recovery operation is performed at the start time of the compressor20, shortage of the refrigerant is prevented, resulting in an increase of the cooling efficiency of the refrigerating chamber14.

As described above, after the freezing chamber12and the refrigerating chamber14are independently cooled, the controller130may determine whether the compressor20is in an OFF condition (S310).

If it is determined in operation310that the compressor20is in the OFF condition, the controller130may perform a second refrigerant recovery operation just before the compressor20stops operation such that the refrigerant remaining in the freezing chamber evaporator32is recovered into the condenser22(S312).

After the refrigerant recovered from the freezing chamber evaporator32is stored in the high-pressure part through the second refrigerant recovery operation re-performed just before the compressor20stops operation, the controller130stops the compressor20through the drive unit150(S314), and finishes the parallel cycle.

A method for variably controlling the refrigerant recovery operation time according to outdoor air temperature will hereinafter be described with reference toFIGS. 10A and 10B.

FIGS. 10A and 10Bare flowcharts illustrating a control algorithm for allowing the refrigerator to change the refrigerant recovery operation time according to an outdoor air temperature according to an embodiment of the present disclosure. Parts ofFIGS. 10A and 10Bidentical to those ofFIGS. 5 and 6are denoted by the same numerals and the same names, and a detailed description thereof will not be given.

Referring toFIGS. 10A and 10B, the outdoor air temperature sensor110may detect outdoor air temperature of the surrounding area of the refrigerator1, and may transmit the detected outdoor air temperature to the controller130(S400).

Therefore, the controller130may establish the refrigerant recovery operation times (t1, t2) for carrying out refrigerant recovery operations, respectively, according to the outdoor air temperature detected by the outdoor air temperature sensor110(S402).

The refrigerant recovery operation times (t1, t2) may be variably controlled according to different outdoor air temperatures.

For example, if the outdoor air temperature is in a range of 29˜39° C., each of the refrigerant recovery operation times (t1, t2) respectively performed when the compressor20starts operation and before the compressor20stops operation may be set to 50 seconds.

If the outdoor air temperature is in a range of 22˜28° C., each of the refrigerant recovery operation times (t1, t2) respectively performed when the compressor20starts operation and before the compressor20stops operation may be set to 40 seconds.

If the outdoor air temperature is in a range of 22˜28° C., the refrigerant recovery operation time (t1) performed when the compressor20starts operation may be set to 40 seconds, and the refrigerant recovery operation time (t2) performed before the compressor20stops operation may be set to 50 seconds.

If the outdoor air temperature is in a range of 8˜21° C., each of the refrigerant recovery operation times (t1, t2) respectively performed when the compressor20starts operation and before the compressor20stops operation may be set to 30 seconds.

If the outdoor air temperature is in a range of 8˜21° C., the refrigerant recovery operation times (t1) performed when the compressor20starts operation may be set to 30 seconds, and the refrigerant recovery operation time (t2) performed before the compressor20stops operation may be set to 50 seconds.

In other words, each of the refrigerant recovery operation times (t1, t2) may be increased in proportion to the increasing outdoor air temperature. Since thermal load based on a difference between outdoor air temperature and indoor air temperature is increased in proportion to the increasing outdoor air temperature, heat exchange amount in the refrigerating chamber evaporator34is increased, such that a large amount of refrigerant is needed. Therefore, each of the refrigerant recovery operation times (t1, t2) is increased in proportion to the increasing outdoor air temperature, such that the refrigerant recovery amount increases.

As described above, the refrigerant recovery operation times (t1, t2) are variably controlled according to the outdoor air temperature, such that the operation efficiency of the refrigerating chamber14may increase. In this case, the refrigerant recovery operation times (t1, t2) are not limited thereto, and can also be changed in various ways according to the capacity or design structure of the refrigerator1as necessary.

If the refrigerant recovery operation times (t1, t2) are set according to outdoor air temperature, the indoor air temperature sensor100may detect indoor air temperatures of the freezing chamber12and the refrigerating chamber14, and may transmit the detected indoor air temperatures to the controller130.

Therefore, the controller130may compare the indoor air temperatures (detected by the indoor air temperature sensors100) of the freezing chamber12and the refrigerating chamber14with the setting temperatures, and may determine whether the start time of the compressor20is achieved (S404).

If it is determined in operation404that the start time of the compressor20is achieved, the controller130may start operation of the compressor20through the drive unit150(S406).

Subsequently, the controller130may perform a first refrigerant recovery operation to recover the refrigerant remaining in the freezing chamber evaporator32into the side of the condenser22at the start time of the compressor20(S408).

In this case, the controller130may count the refrigerant recovery operation time in which the refrigerant remaining in the freezing chamber evaporator32moves to the side of the condenser22through the first refrigerant recovery operation performed when the compressor20starts operation (S410), and may determine whether the first time (t1) has elapsed (S412).

If it is determined in operation412that the first time has elapsed, the controller130may switch on the flow passage switching valve26in the R direction (i.e., the refrigerating chamber direction) shown inFIG. 6so as to cool the refrigerating chamber14.

If the flow passage switching valve26is switched on in the R direction (i.e., the refrigerating chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→refrigerating chamber expansion unit30→refrigerating chamber evaporator34→compressor20in the refrigerating chamber operation mode, thereby performing the cooling operation of the refrigerating chamber14(S414).

After the indoor air temperature of the refrigerating chamber14reaches the setting temperature, the controller130may switch on the flow passage switching valve26in the F direction (i.e., the freezing chamber direction) shown inFIG. 6so as to cool the freezing chamber12.

If the flow passage switching valve26is switched on in the F direction (i.e., the freezing chamber direction), the refrigerant may circulate in the order of compressor20→condenser22→hot pipe24→flow passage switching valve26→freezing chamber expansion unit28→freezing chamber evaporator32→compressor20in the freezing chamber operation mode, thereby performing the cooling operation of the freezing chamber12(S416).

As described above, after the freezing chamber12and the refrigerating chamber14are independently cooled, the controller130may determine whether the compressor20is in an OFF condition (S418).

If it is determined in operation418that the compressor20is in the OFF condition, the controller130may perform a second refrigerant recovery operation just before the compressor20stops operation such that the refrigerant remaining in the freezing chamber evaporator32is recovered into the condenser22(S420).

In this case, the controller130may count the refrigerant recovery operation time in which the refrigerant remaining in the freezing chamber evaporator32is stored in the high-pressure part through the second refrigerant recovery operation performed just before the compressor20stops operation (S422), and may determine whether the second time (t2) has elapsed (S424).

If it is determined in operation424that the second time has elapsed, the controller130stops the compressor20through the drive unit150(S426), and finishes the parallel cycle.

In the meantime, although the embodiment of the present disclosure has exemplarily disclosed that outdoor air temperature of the peripheral part of the refrigerator1is detected before it is determined whether the start time of the compressor20is achieved, the scope or spirit of the present disclosure is not limited thereto, and the embodiment can also detect outdoor air temperature after determining whether the start time of the compressor20is achieved.

As is apparent from the above description, the refrigerator and the method for controlling the same according to the embodiments of the present disclosure can guarantee a sufficiently long refrigerant recovery operation time by performing the refrigerant recovery operation not only when the compressor starts operation but also before the compressor stops operation, resulting in implementation of the highest operation efficiency of a refrigerating chamber. In addition, the refrigerator can guarantee high reliability of the compressor by increasing the refrigerant recovery amount within a predetermined pressure range in which the compressor can operate, and can maintain an optimum refrigerant amount by variably controlling the refrigerant recovery operation time according to the outdoor air temperature, resulting in improvement of energy efficiency.

Although a few embodiments of the present disclosure have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined in the claims and their equivalents.