AU2005201546B2

AU2005201546B2 - Refrigerator and control method thereof

Info

Publication number: AU2005201546B2
Application number: AU2005201546A
Authority: AU
Inventors: Hak Gyun Bae; Eung Ryeol Seo
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2005-03-16
Filing date: 2005-04-13
Publication date: 2007-03-22
Anticipated expiration: 2025-04-13
Also published as: AU2005201546A1

Description

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TITLE OF THE INVENTION REFRIGERATOR AND CONTROL METHOD THEREOF CROSS-REFERENCE TO RELATED APPLICATION This application claims priority from Korean Patent Application No. P2005-

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S 5 21920, filed on March 16, 2005 in the Korean Intellectual Property Office, the o disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator, and, more particularly, to a refrigerator defined with freezing and refrigerating compartments, and equipped with independent evaporators respectively installed at the freezing and refrigerating compartments.

2. Description of the Related Art Generally, a refrigerator includes a body defined with freezing and refrigerating compartments partitioned by an intermediate partition wall. Doors are hingably coupled to the refrigerator body in front of the freezing and refrigerating compartments to open and close the freezing and refrigerating compartments, respectively. An evaporator and a fan are arranged at an inner wall portion of the refrigerator body defining the freezing compartment, in order to generate cold air and to supply the generated cold air to the freezing compartment. Another evaporator and another fan are arranged at an inner wall portion of the refrigerator body defining the refrigerating compartment, in order to generate cold air and to supply the generated cold air to the refrigerating compartment. Thus, cold air is supplied into the freezing and refrigerating compartments in an independent fashion. Such a system is called an "independent cooling system".

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The reason why the system of cooling the freezing and refrigerating compartments in an independent fashion is used is that the target cooling Cf temperature required in the refrigerating compartment is relatively higher than that required in the freezing compartment. In order to implement different cooling I 5 temperatures in the freezing and refrigerating compartments, respectively, the evaporators of the freezing and refrigerating compartments should have different o evaporation temperatures, respectively. To this end, expansion (pressure reduction) n of a refrigerant at an upstream side from each evaporator should be carried out in osuch a manner that the expansion degrees at respective upstream sides from the evaporators are different from each other. Accordingly, separate expansion devices are installed at respective upstream ends of the evaporators.

The independent cooling system may also implement independent cooling of a selected one of the freezing and refrigerating compartments. In order to independently cool a selected one of the freezing and refrigerating compartments, it is necessary to control a flow path of the refrigerant such that the refrigerant circulates through an associated one of the evaporators for the freezing and refrigerating compartments.

Different evaporation temperatures of the evaporators for the freezing and refrigerating compartments mean different refrigerant pressures of the evaporators.

Such a refrigerant pressure difference causes the refrigerant to flow through one. of the evaporators in a larger quantity, so that the refrigerant may not smoothly flow through the other evaporator when the refrigerant flow path is changed.

SUMMARY OF THE INVENTION Therefore, it is an aspect of the invention to provide a refrigerator capable of providing a smooth flow of a refrigerant through two evaporators having different pressures in accordance with an effective control for a path change valve when a flow path of the refrigerant is changed between the high-pressure-side and lowpressure-side evaporators by the path change valve.

O 3 0 Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or nmay be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are addressed by providing a refrigerator including a plurality of evaporators, a path change device, Iand a controller The plurality of evaporators may comprise at least one lowpressure-side evaporator and at least one high-pressure-side evaporator. The path ochange device may change a flow path of a refrigerant between the low-pressure- 0side evaporator and the high-pressure-side evaporator, and may have a simultaneous opening stage to simultaneously establish refrigerant flow paths respectively communicating with the low-pressure-side evaporator and the highpressure-side evaporator during the path change. The controller may control the path change device such that the simultaneous opening stage established when the flow path of the refrigerant is changed from the low-pressure-side evaporator to the high-pressure-side evaporator is longer than the simultaneous opening stage established when the flow path of the refrigerant is changed from the high-pressureside evaporator to the low-pressure-side evaporator.

The low-pressure-side evaporator may be a freezing compartment evaporator to cool a freezing compartment of the refrigerator, and the high-pressureside evaporator may be a refrigerating compartment evaporator to cool a refrigerating compartment of the refrigerator.

The simultaneous opening stage established when the flow path of the refrigerant is changed from the high-pressure-side evaporator to the low-pressureside evaporator may be an opening stage inevitably established due to a mechanical characteristic limitation of the path change device, and the simultaneous opening stage established when the flow path of the refrigerant is changed from the lowpressure-side evaporator to the high-pressure-side evaporator may be an intentional opening stage longer than the inevitable simultaneous opening stage.

The path change device may be a 3-way valve to change the refrigerant 4

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flow path in accordance with a rotation of a stepping motor, and the mechanical characteristic limitation of the path change device may be a rotating speed limitation n of the stepping motor.

According to another aspect, the present invention provides a refrigerator including a plurality of evaporators, and a path change device. The plurality of Ievaporators may comprise at least one low-pressure-side evaporator and at least one high-pressure-side evaporator. The path change device may change a flow opath of a refrigerant between the low-pressure-side evaporator and the high- 0pressure-side evaporator, and may have a simultaneous opening stage to simultaneously establish refrigerant flow paths respectively communicating with the low-pressure-side evaporator and the high-pressure-side evaporator when the refrigerant flow path is changed from the low-pressure-side evaporator to the highpressure-side evaporator.

In accordance with another aspect, the present invention provides a refrigerator including a refrigerating compartment evaporator, a freezing compartment evaporator, a first expansion device, a second expansion device, a path change device, and a controller. The first expansion device may expand a flow of a refrigerant introduced into the refrigerating compartment evaporator to a first pressure, and the second expansion device may expand a flow of the refrigerant introduced into the freezing compartment evaporator to a second pressure lower than the first pressure. The path change device may change a flow path of a refrigerant between the freezing compartment evaporator and the refrigerating compartment evaporator, and may have a simultaneous opening stage to simultaneously establish refrigerant flow paths respectively communicating with the freezing compartment evaporator and the refrigerating compartment evaporator when the flow path of the refrigerant is changed from the freezing compartment evaporator to the refrigerating compartment evaporator.

The controller may control the path change device so that the simultaneous opening stage is maintained for a predetermined time when the refrigerant flow path O

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is changed from the freezing compartment evaporator to the refrigerating compartment evaporator BRIEF DESCRIPTION OF THE DRAWINGS The above and/or other aspects of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings, in which: 0 0FIG. 1 is a circuit diagram illustrating a refrigerant cycle established in a refrigerator according to an exemplary embodiment of the present invention; FIG. 2 is a timing chart illustrating a concept of controlling a 3-way valve in the refrigerator according to the illustrated embodiment of the present invention; FIG. 3 is a block diagram illustrating a control system used in the refrigerator according to the illustrated embodiment of the present invention; FIG. 4 is a flow chart illustrating a method for controlling the 3-way valve to change a refrigerant flow path from a refrigerating compartment evaporator to a freezing compartment evaporator; and FIG. 5 is a flow chart illustrating a method for controlling the 3-way valve to change the refrigerant flow path from the freezing compartment evaporator to the refrigerating compartment evaporator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to FIGS. 1 to 4. FIG. 1 is a circuit diagram illustrating a refrigerant cycle established in a refrigerator according to an exemplary embodiment of the present invention. Referring to FIG. 1, a refrigerant, which is discharged from a compressor 201, may be introduced into a refrigerating compartment capillary tube 304 or a freezing compartment capillary tube 308 after passing through a condenser 302 when a flow path thereof is changed in accordance with operation of a 3-way tt~) 6 valve 310. For example, when the 3-way valve 310 is operated such that a refrigerating compartment valve 310a thereof is closed, whereas a freezing en compartment valve 310b thereof is opened, the refrigerant emerging from the condenser 302 is introduced only into the freezing compartment evaporator 207 ID 5 through the freezing compartment capillary tube 308. In this case, cooling is carried out in the freezing compartment 220 alone. On the other hand, in a refrigerating compartment cooling mode in which both the refrigerating compartment 210 and the In freezing compartment 220 are cooled, the 3-way valve 310 is operated to open the compartment valve 310Oa while closing the freezing compartment valve 310b. In this case, the refrigerant emerging from the condenser 302 is introduced into the refrigerating compartment evaporator 205 and then into the freezing compartment evaporator 207 via the refrigerating compartment capillary tube 304 and a connecting capillary tube 306.

The 3-way valve 310 is configured to change the refrigerant flow path in accordance with rotation of a stepping motor (not shown). That is, a refrigerant flow path, which communicates with at least one of the refrigerating compartment evaporator 205 and freezing compartment evaporator 207, is established in accordance with rotation of the stepping motor. The change of the refrigerant flow path caused by rotation of the stepping motor will now be described with reference to FIG. 2.

FIG. 2 is a timing chart illustrating a concept of controlling the 3-way valve in the refrigerator according to the illustrated embodiment of the present invention. As shown in FIG. 2, a refrigerant flow path is established when a selected one of the refrigerating compartment valve 310a and freezing compartment valve 310b is opened in accordance with a rotation angle of the stepping motor. When the rotation angle of the stepping motor is 34Q, both the refrigerating compartment valve 310a and the freezing compartment valve 310b are closed, so that no refrigerant flow path is established which communicates with the refrigerating compartment evaporator 205 or freezing compartment evaporator 207. When the stepping motor further rotates to about 950, the freezing compartment valve 310b is opened while the tt~) 7 refrigerating compartment valve 310b is still in the closed state thereof. In this state, a refrigerant flow path is established which communicates with the freezing en compartment evaporator 207 via the freezing compartment capillary tube 308. In accordance with a further rotation of the stepping motor to about 1540, the ID 5 refrigerating compartment valve 310b is also opened. That is, a simultaneous opening stage, in which both the refrigerating compartment valve 310a and the freezing compartment valve 310b are opened, is established. When the stepping In motor further rotates to about 1950, the freezing compartment valve 310b is closed while the refrigerating compartment valve 310a is still in the opened state thereof. In state, a refrigerant flow path is established which communicates with only the refrigerating compartment evaporator 205 via the refrigerating compartment capillary tube 304. In accordance with a further rotation of the stepping motor to 2150, both the refrigerating compartment valve 310a and the freezing compartment valve 310b are closed. As a result, there is no refrigerant flow path communicating with the refrigerating compartment capillary tube 304 or the freezing compartment capillary tube 308.

In such a manner, establishment of a desired refrigerant flow path is determined in accordance with rotation of the stepping motor adapted to control opening/closing of the 3-way valve 310. As described above, in a certain rotation angle range of the stepping motor, for example, about 154' in the case of FIG. 2, there is a simultaneous opening stage tO in which both the refrigerating compartment valve 310a and the freezing compartment valve 310b are -opened. In this stage to, the refrigerant can flow toward both the refrigerating compartment evaporator 205 and the freezing compartment evaporator 207. In the simultaneous opening stage tO, however, the refrigerant flows toward the refrigerating compartment evaporator 205 in a larger quantity because the pressure of the freezing compartment evaporator 207 is relatively lower than that of the refrigerating compartment evaporator 205. For this reason, when the operation mode of the refrigerator is changed from a mode for cooling the freezing compartment alone to a mode for cooling the refrigerating compartment alone (that is, the rotation angle of the stepping motor is changed from 950 to 1950 via the range of about 1540), the refrigerant, which flows toward the Ic) 8 freezing compartment evaporator 207, instantaneously flows back toward the refrigerating compartment evaporator 205. As a result, it is impossible to sufficiently en supply the refrigerant toward the freezing compartment evaporator 207. This is because the refrigerant present in the refrigerating compartment evaporator 205 is I 5 introduced into the freezing compartment evaporator 207 in the mode for cooling the freezing compartment alone because the pressure of the freezing compartment oevaporator 207 is lower than the pressure of the refrigerating compartment evaporator 205, so that the quantity of the refrigerant left in the refrigerating compartment evaporator 205 in the mode for cooling the freezing compartment alone is little. In order to solve this problem, when the operation mode of the refrigerator is changed from the mode for cooling the freezing compartment alone to the mode for cooling the refrigerating compartment alone, that is, when the rotation angle of the stepping motor is changed from 950 to 1950 via the range of about 1540, the simultaneous opening stage tO corresponding to the range of about 1540 is maintained for a relatively lengthened period of time (about 10 seconds). In this case, the refrigerant can flow into both the refrigerating compartment evaporator 205 and the freezing compartment evaporator 207 for a sufficient period of time to allow the refrigerant to be sufficiently and smoothly supplied through the refrigerant flow path communicating with the refrigerating compartment evaporator 205 without being cut off.

In order to achieve such a control operation, the refrigerator according to the illustrated embodiment of the present invention includes a control system shown in FIG. 3. FIG. 3 is a block diagram illustrating the control system used in the refrigerator according to the illustrated embodiment of the present invention.

Referring to FIG. 3, an input unit 354 and a temperature detector 356 are connected to an input of a controller 352 adapted to control the overall operation of the refrigerator. The input unit 354 allows the user to set a desired target cooling temperature, a desired cooling mode, or other operating conditions. The temperature detector 356 detects respective temperatures of the refrigerating compartment 210, freezing compartment 220, refrigerating compartment evaporator 205, and freezing compartment evaporator 207, and informs the controller 352 of the I) 9

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detected temperatures. Based on the detected temperatures, the controller 352 controls the cooling operation of the refrigerator. The 3-way valve 310 is electrically nconnected to an output of the controller 352, along with a compressor 201. The 3way valve 310 and compressor 201 are controlled by the controller 352 to implement a cooling mode set by the user and to achieve a target cooling temperature set by '1 the user. Such a control operation of the controller 352 will now be described with reference to FIGS. 4 and oFIG. 4 is a flow chart illustrating a method for controlling the 3-way valve to change the refrigerant flow path from the refrigerating compartment evaporator to the freezing compartment evaporator As shown in FIG. 4, in a state of the 3-way valve 310 corresponding to a 195 0 -rotated state of the stepping motor, the refrigerating compartment valve 310a is opened, whereas the freezing compartment valve 310b is closed. In this state, accordingly, a refrigerating cooling mode is executed to sequentially cool both the refrigerating compartment 210 and the freezing compartment 220 (Operation 402). After completion of the cooling of the refrigerating compartment 210 to the target refrigerating compartment temperature, the controller 352 determines whether or not the temperature of the freezing compartment 220 reaches the target freezing compartment temperature, and thus, determines whether or not it is necessary to cool the freezing compartment 220 alone. Based on this determination, the controller 352 determines whether or not the refrigerant flow path is to be changed from the refrigerating compartment 210 to the freezing compartment 220 for execution of the mode for cooling the freezing compartment 220 alone (Operation 404). When it is necessary to change the refrigerant flow path from the refrigerating compartment 210 to the freezing compartment 220, the controller 352 changes the rotation angle of the stepping motor from 195 to 1540 (Operation 406). This procedure is an intermediate procedure involved in a procedure in which the stepping motor is rotated to 950 In accordance with the intermediate procedure, a simultaneous opening stage is established, in which both the refrigerating compartment valve 310a and the freezing compartment valve 310b are opened. Where the refrigerant flow path is to be changed from the refrigerating compartment 210 to the freezing compartment 220, the stepping motor is rotated to

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without any intentional delay in the simultaneous opening stage, thereby closing the refrigerating compartment valve 310a while opening only the freezing ncompartment valve 310b to cool only the freezing compartment 220. That is, the mode for cooling the freezing compartment 220 alone is executed (Operation 408).

The simultaneous opening stage, in which both the refrigerating compartment valve 310a and the freezing compartment valve 310b are opened, is limited to a minimal period (for example, 3 seconds) inevitably present in accordance with the rotating Ispeed of the stepping motor. Of course, when the rotating speed of the stepping omotor is very high, such a simultaneous opening stage may not exist. Thus, the time, for which both the valves 310a and 310b are opened, is minimized during the change of the refrigerant flow path from the refrigerating compartment 210 to the freezing compartment 220. Accordingly, it is possible to reduce the degree of concentration of the refrigerant from the refrigerating compartment evaporator 205 to the freezing compartment evaporator 207.

FIG. 5 is a flow chart illustrating a method for controlling the 3-way valve to change the refrigerant flow path from the freezing compartment evaporator to the refrigerating compartment evaporator. As shown in FIG. 5, in a state of the 3-way valve 310 corresponding to a 95 0 -rotated. state of the stepping motor, the refrigerating compartment valve 310a is closed, whereas the freezing compartment valve 310b is opened. In this state, accordingly, the mode for cooling the freezing compartment 220 alone is executed (Operation 502). After completion of the cooling of the freezing compartment 220 to the target freezing compartment temperature, it is determined whether or not the refrigerating compartment 210 is to be cooled.

Based on this determination, it is then determined whether or not the refrigerant flow path is to be changed from the freezing compartment 220 to the refrigerating compartment 210 for execution of the refrigerating compartment cooling mode (Operation 504). When it is necessary to change the refrigerant flow path from the freezing compartment 220 to the refrigerating compartment 210, the rotation angle of the stepping motor is changed from 950 to 154' (Operation 506). This procedure is an intermediate procedure involved in a procedure in which the stepping motor is rotated to 1950. In accordance with the intermediate procedure, a simultaneous 11 0 opening stage, in which both the refrigerating compartment valve 310a and the freezing compartment valve 310 Ob are opened, is established. Where the refrigerant cf flow path is to be changed from the freezing compartment 220 to the refrigerating compartment 210, the simultaneous opening stage established in the intermediate procedure is continued for a predetermined intentional time (for example, seconds) in accordance with the illustrated embodiment of the present invention.

That is, both the refrigerating compartment valve 310a and the freezing compartment valve 310b are opened for the predetermined intentional time (Operation 508). As oboth the valves 310a and 310b are opened for the predetermined time during the change of the refrigerant flow path from the freezing compartment 220 to the refrigerating compartment 210, as described above, the refrigerant, which has already been supplied into the freezing compartment evaporator 207, is sufficiently changed from a liquid phase to a gas phase, in order to prevent a liquid refrigerant from entering the compressor 201. Preferably, the predetermined intentional time is set to be longer than the simultaneous opening stage (for example, 3 seconds) inevitably present due to the mechanical characteristics of the stepping motor and 3way valve 310 when the change of the refrigerant flow path from the refrigerating compartment evaporator 210 to the freezing compartment 220 is carried out (that is, when the stepping motor is rotated from 195 to 950), in order to more or less delay the point of time when the supply of the refrigerant to the freezing compartment evaporator 207 is cut off. For example, the predetermined intentional time may be seconds. After the predetermined time (10 seconds) elapses, the stepping motor is rotated to 195', thereby closing the freezing compartment valve 310b while maintaining only the refrigerating compartment valve 310a in the opened state thereof. That is, the refrigerating compartment cooling mode is executed, in which the refrigerating compartment 210 and freezing compartment 220 are sequentially cooled (Operation 510).

Although the valve employing the stepping motor is used as a path change device in the illustrated embodiment of the present invention, a valve employing a solenoid may be used.

0 12 0 In accordance with the refrigerator control method of the present invention, it is possible to effectively control a path change valve adapted to change a flow path cf of a refrigerant between evaporators having different pressures such that the quantity of the refrigerant supplied into the low-pressure-side evaporator is gradually reduced, and the quantity of the refrigerant supplied into the high-pressure-side evaporator is gradually increased, when the flow path of the refrigerant is changed from the low-pressure-side evaporator to the high-pressure-side evaporator.

IAccordingly, it is possible to prevent introduction of a liquid refrigerant into a ocompressor caused by insufficient phase change of the refrigerant (from a liquid phase to a gas phase) occurring in the low-pressure-side evaporator when the supply of the refrigerant to the low-pressure-side evaporator is suddenly cut off.

In the specification the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and "comprises".

Although a few preferred embodiments of the present invention 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 invention, the scope of which is defined in the claims and their equivalents.

Claims

2. The refrigerator according to claim 1, wherein: the low-pressure-side evaporator is a freezing compartment evaporator to cool a freezing compartment of the refrigerator; and the high-pressure-side evaporator is a refrigerating compartment evaporator to cool a refrigerating compartment of the refrigerator.
3. The refrigerator according to claim 1, wherein: the simultaneous opening stage established when the flow path of the refrigerant is changed from the high-pressure-side evaporator to the low-pressure- side evaporator is an opening stage inevitably established due to a mechanical characteristic limitation of the path change device; and the simultaneous opening stage established when the flow path of the refrigerant is changed from the low-pressure-side evaporator to the high-pressure- 14 0 side evaporator is an intentional opening stage longer than the inevitable simultaneous opening stage.
4. The refrigerator according to claim 3, wherein: IN the path change device is a 3-way valve to change the refrigerant flow path in accordance with a rotation of a stepping motor; and the mechanical characteristic limitation of the path change device is a rotating speed limitation of the stepping motor. 0 A method for controlling a refrigerator including a plurality of evaporators comprising at least one low-pressure-side evaporator and at least one high-pressure-side evaporator, and a path change device to change a flow path of a refrigerant between the low-pressure-side evaporator and the high-pressure-side evaporator, the path change device having a simultaneous opening stage to simultaneously establish refrigerant flow paths respectively communicating with the low-pressure-side evaporator and the high-pressure-side evaporator during the path change, the method comprising: controlling the path change device such that the simultaneous opening stage established when the flow path of the refrigerant is changed from the low-pressure- side evaporator to the high-pressure-side evaporator is longer than the simultaneous opening stage established when the flow path of the refrigerant is changed from the high-pressure-side evaporator to the low-pressure-side evaporator.
6. The method according to claim 5, wherein: the low-pressure-side evaporator is a freezing compartment evaporator to cool a freezing compartment of the refrigerator; and the high-pressure-side evaporator is a refrigerating compartment evaporator to cool a refrigerating compartment of the refrigerator.
7. The method according to claim 5, wherein: the simultaneous opening stage established when the flow path of the refrigerant is changed from the high-pressure-side evaporator to the low-pressure- side evaporator is an opening stage inevitably established due to a mechanical S characteristic limitation of the path change device; and the simultaneous opening stage established when the flow path of the refrigerant is changed from the low-pressure-side evaporator to the high-pressure- O 5 side evaporator is an intentional opening stage longer than the inevitable simultaneous opening stage.
8. The method according to claim 7, wherein: Sthe path change device is a 3-way valve to change the refrigerant flow path in accordance with a rotation of a stepping motor; and 0 the mechanical characteristic limitation of the path change device is a rotating speed limitation of the stepping motor.
9. A refrigerator substantially as hereinbefore described and/or illustrated in any one or more of the accompanying drawings. A method for controlling a refrigerator, substantially as hereinbefore described with reference to any one or more of the accompanying drawings.