WO2009061120A2

WO2009061120A2 - Control method of refrigerator

Info

Publication number: WO2009061120A2
Application number: PCT/KR2008/006499
Authority: WO
Inventors: Dong-Seok Kim; Sung-Hee Kang; Jong-Min Shin; Chulgi Roh; Deok-Hyun Youn
Original assignee: Lg Electronics, Inc.
Priority date: 2007-11-05
Filing date: 2008-11-04
Publication date: 2009-05-14
Also published as: WO2009061120A3

Abstract

The present invention relates to a control method of a refrigerator comprising high- and low- temperature storage compartments, in which a valve is open towards an evaporator in a high temperature section at the end of a cooling cycle in the low temperature storage compartment. In a refrigerator comprising a first storage compartment for storing an item, a second storage compartment for storing an item at a lower temperature than the first storage compartment, a cooling cycle including a compressor, a condenser for condensing a refrigerant from the compressor, a valve for directing the refrigerant from the condenser to first and second evaporators, with the first and second evaporators evaporating supplied refrigerants to cool the first and second storage compartments, respectively, and first and second fans for circulating cool air from the first and second evaporators, respectively, and a controller for controlling the first and second fans, the valve and the compressor, a control method of the refrigerator comprising: a first step of activating the compressor if cooling of the second storage compartment is required, and adjusting the valve to direct a refrigerant towards the second evaporator; and a second step of adjusting the valve to direct refrigerants towards the first evaporator, if the cooling of the second storage compartment is completed.

Description

CONTROL METHOD OF REFRIGERATOR

Technical Field

[1] The present invention relates in general to a control method of a refrigerator, and more particularly, to a control method of a refrigerator comprising high- and low- temperature storage compartments, in which a valve is open towards an evaporator in a high temperature section at the end of a cooling cycle in the low temperature storage compartment. Background Art

[2] FIG. 1 is an explanatory view of a cooling cycle used in refrigerators according to the prior art. The cooling cycle includes a compressor 1, a condenser 2, a valve 3, fans 4 and 5, evaporators 6 and 7, a controller 8, and expansion means 9 and 10. The compressor 1 compresses refrigerants into high-temperature, high-pressure gaseous refrigerants, and the condenser 2 condenses the refrigerants having passed through the compressor to high-temperature, high-pressure liquid refrigerants. The valve 3 controls a refrigerant flow into the evaporator 6 of a high-temperature section and the evaporator 7 of a low-temperature section, and a 3-way valve having one inlet and two outlets is typically used. Hereinafter, an evaporator and a fan corresponding to a storage compartment that stores objects at high temperature will be referred to as a high temperature evaporator and a high temperature fan, respectively. Similarly, an evaporator and a fan corresponding to a storage compartment that stores objects at low temperature will be referred to as a low temperature evaporator and a low temperature fan, respectively. When a refrigerant is sent to the high temperature evaporator 6, the high temperature fan 4 starts running, thereby cooling an upper storage compartment. Likewise, when a refrigerant is sent to the low temperature evaporator 7, the low temperature fan 5 starts running thereby cooling a lower storage compartment. That is, the high temperature fan 4 has a role in circulating cool air generated from the high temperature evaporator 6 into the high temperature storage compartment, and the low temperature fan 5 has a role in circulating cool air generated from the low temperature evaporator 7 into the low temperature storage compartment.

[3] In such a refrigerator, the high temperature storage compartment and the low temperature storage compartment are cooled off as the compressor 1 and the valve 3 operate differently by time. In detail, to supply cool air into the high temperature storage compartment, the compressor 1 operates and the valve 3 is adjusted to send re- frigerants to the high temperature evaporator 6. To supply cool air into the low temperature evaporator 7, the compressor 1 operates and the valve 3 is adjusted to send refrigerants to the low temperature evaporator 7. If cool air is no longer needed in the high temperature storage compartment and the low temperature storage compartment, the valve 3 returns to its previous state, and the compressor 1 is deactivated.

[4] FIG. 2 graphically explains a control method of a parallel-type refrigerator according to the prior art. In the graph, 'High' (tθ-tl and t4-t5) indicates that refrigerants are sent to the high temperature evaporator 6 to cool the high temperature storage compartment, and 'Low' (t2-t3 and t6-t7) indicates that refrigerants are sent to the low temperature evaporator 7 to cool the low temperature storage compartment.

[5] When cooling the high temperature storage compartment (e.g., tθ), first, a valve outlet is open only towards the side of the high temperature evaporator 6 to let refrigerants enter the high temperature evaporator 6, and the refrigerants having passed through the high temperature evaporator 6 are then sent to the compressor 1 again. When the cooling operation on the high temperature storage compartment is over in a set amount of time, refrigerants are no longer supplied from the compressor 1 to the high temperature evaporator 6 (tl). Similarly, when cooling the low temperature storage compartment (e.g., t2), first, a valve outlet is open only towards the side of the low temperature evaporator 7 to let refrigerants enter the low temperature evaporator . 7, and the refrigerants having passed through the low temperature evaporator 7 are then sent to the compressor 1 again. When the cooling operation on the low te mperature storage compartment is over in a set amount of time, refrigerants are no longer supplied from the compressor 1 to the low temperature evaporator 7 (t3). Here, the valve 3 returns to its original state at tl and t3 when the cooling operation on the high temperature storage compartment and the cooling operation on the low temperature storage compartment have ended. That is, from tl to t2, only the high temperature evaporator side remains open, and from t3 to t4, only the low temperature evaporator side remains open.

[6] When cooling of the low temperature storage compartment has ended, the compressor 1 is deactivated, and the valve 3 is open only towards the low temperature evaporator 7. After the compressor 1 is deactivated, refrigerants inside the compressor 1 pass through the condenser 2 and travel to the low temperature evaporator 7. While in this state, if refrigerants needs to be supplied to the high temperature storage compartment for cooling (t4 in FIG. 2), the conventional control method send the refrigerants that have previously travelled to the low temperature evaporator 7 to the high temperature evaporator 6, via the compressor 1 and the condenser 2 again. In addition, if there is a large temperature gap between the low temperature evaporator 7 and the high temperature evaporator 6, it is not easy to move the refrigerants having already travelled to the low temperature evaporator 7 to the high temperature evaporator 6 via the compressor 1 and the condenser 2 again. Because of this, cooling the high temperature storage compartment again is hard and inefficient, and some of the refrigerants still remain in the low temperature evaporator. Disclosure of Invention Technical Problem

[7] The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to reduce a residual amount of refrigerants in a low temperature storage compartment, by adjusting the valve at the completion of a cooling operation on the low temperature storage compartment.

[8] Another object of the present invention is to facilitate the circulation of refrigerants for efficient cooling by adjusting the valve at the completion of a cooling operation on the low temperature storage compartment. Technical Solution

[9] According to an aspect of the present invention, in a refrigerator comprising a first storage compartment for storing an item, a second storage compartment for storing an item at a lower temperature than the first storage compartment, a cooling cycle including a compressor, a condenser for condensing a refrigerant from the compressor, a valve for directing the refrigerant from the condenser to first and second evaporators, with the first and second evaporators evaporating supplied refrigerants to cool the first and second storage compartments, respectively, and first and second fans for circulating cool air from the first and second evaporators, respectively, and a controller for controlling the first and second fans, a control method of the refrigerator comprising: a first step of activating the compressor if cooling of the second storage compartment is required, and adjusting the valve to direct a refrigerant towards the second evaporator; and a second step of adjusting the valve to direct refrigerants towards the first evaporator, if the cooling of the second storage compartment is completed.

[10] In the second step, the compressor is deactivated after the cooling of the second storage compartment is completed.

[11] In the second step, if the first storage compartment needs to be cooled off after the valve has been adjusted, the compressor is reactivated and then the valve is adjusted to a position to direct a refrigerant towards the first evaporator.

[12] The first step preferably includes a step of deciding whether the second storage compartment needs to be cooled off.

[13] Another aspect of the present invention provides a refrigerator, comprising: a first storage compartment for storing an item and a second storage compartment for storing an item at a lower temperature than the first storage compartment; a cooling cycle including a compressor, a condenser for condensing a refrigerant from the compressor, a valve for directing the refrigerant from the condenser to first and second evaporators, with the first and second evaporators evaporating supplied refrigerants to cool the first and second storage compartments, respectively, first and second fans for circulating cool air from the first and second evaporators, respectively; and a controller for performing a cooling operation on each of the first and second storage compartments and adjusting the valve, after cooling of the second storage compartment is completed, to direct refrigerants towards the first evaporator.

[14] The refrigerator further comprises sensing units for sensing temperatures of the first and second evaporators.

[15] In the refrigerator, the controller deactivates the operation of the compressor after cooling of the second storage compartment is completed.

[16] In the refrigerator, if the controller decides that the first storage compartment needs to be cooled off after having deactivated the operation of the compressor, the controller reactivates the compressor and adjusts the valve to a position to direct a refrigerant towards the first evaporator. Advantageous Effects

[17] The refrigerant control method in accordance with the present invention is effective for reducing a residual amount of refrigerants in a low temperature storage compartment, through adjustment of the valve at the completion of a cooling operation on the low temperature storage compartment.

[18] Moreover, the refrigerant control method in accordance with the present invention facilitates the circulation of refrigerants for efficient cooling through adjustment the valve at the completion of a cooling operation on the low temperature storage compartment. Brief Description of the Drawings

[19] FIG. 1 is an explanatory view of a cooling cycle used in refrigerators according to the prior art;

[20] FIG. 2 graphically explains a control method of a parallel-type refrigerator according to the prior art;

[21] FIG. 3 is a schematic view for explaining a control method of a refrigerator according to the present invention;

[22] FIG. 4 graphically explains a control method of a parallel-type refrigerator according to the present invention; and

[23] FIG. 5 is a flow chart explaining a control method of a refrigerator according to the present invention. Mode for the Invention

[24] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[25] FIG. 3 is a schematic view for explaining a control method of a refrigerator according to the present invention. Referring to FIG.l, a refrigerator 20 includes temperature sensors 21 for measuring the temperature of a high temperature evaporator 6, the temperature of a low temperature evaporator 7, and the internal temperatures of high temperature storage compartment and low temperature storage compartment, a defrost sensor 23 for sensing whether the high temperature evaporator 6 and the low temperature evaporator 7 have been frosted, a defrost heater 24 for applying heat to defrost the evaporators 6 and 7 if they have been frosted, a fan drive unit 31 for activating a high temperature fan 4 or a low temperature fan 5, a valve drive unit 32 for adjusting a valve 3 to direct refrigerants towards the high temperature evaporator 6, or direct refrigerants towards the low temperature evaporator 7, or block both passages, a compressor drive unit 33 for activating or deactivating a compressor 1, and a controller 40 for controlling the fan drive unit 31, the valve drive unit 32 and the compressor drive unit 33, based on information received from the temperature sensors 21 and the defrost sensor 23.

[26] The temperature sensors 21, each of which is mounted on inner wall surface of the high temperature storage compartment and the low temperature storage compartment, sense the internal temperature of the compartments, respectively, and provide the temperature measurement to the controller 40. In addition, the temperature sensors 21 may sense the temperatures of the high- and low- temperature evaporators 6 and 7 and provide the temperature measurement to the controller 40. Sensing the interior temperature of the refrigerator or the evaporator can be done under a command of the controller 40, or may be done automatically at fixed time intervals. [27] The defrost sensor 23 can be implemented in the form of a sensor with a variable resistance in response to the temperature of the high temperature evaporator 6 or the low temperature evaporator 7. The controller 40 receives a signal corresponding to a resistance that varies depending on the temperature of the high temperature evaporator 6 or the low temperature evaporator 7, for deciding whether either one should be defrosted.

[28] The defrost heater 24, at an activation command from the controller 40, removes frost from the high temperature evaporator 6 or the low temperature evaporator 7 by applying heat to the corresponding evaporator. With the supply of heat, the frost having been produced when water vapor around the high temperature evaporator 6 or the low temperature evaporator 7 condenses and deposited on the surface melts or is evaporated to disappear.

[29] The fan drive unit 31, at an activation command from the controller 40, activates the high temperature fan 4 or the low temperature fan 5. Particularly, the high temperature fan 4 distributes a flow of cooling air generated from the high temperature evaporator 6 into the high temperature storage compartment, and the low temperature fan 5 distributes a flow of cooling air generated from the low temperature evaporator 7 into the low temperature storage compartment. In normal case, the fan is activated when refrigerants are fed to an evaporator corresponding to the fan, or is deactivated when no refrigerant is fed to the evaporator corresponding to the fan, or is repeatedly activated and deactivated at regular time intervals for the distribution of the interior temperature.

[30] The valve drive unit 32 regulates the operation of the valve 3, more specifically, it enables refrigerants to flow to the high temperature evaporator 6 or the low temperature evaporator 7, or to block the flow of refrigerants, in response to a command from the controller 40.

[31] The compressor drive unit 33 activates the compressor and determines whether to activate or deactivate the compressor, in response to a signal from the controller 40.

[32] The controller 40 receives a temperature input from each temperature sensor 21. It should be understood that the controller 40 has a timer. The controller compares the temperature input with a set temperature that is predetermined for the high temperature storage compartment or a set temperature that is predetermined for the low temperature storage compartment so as to decide the necessity for cooling of each storage compartment. Furthermore, the controller 40 may also decide the necessity for cooling of each storage compartment at pre-set times. In conformity with the decision on cooling the controller 40 sends an activation command to the valve drive unit 32 to direct or block the flow of refrigerants to the high temperature evaporator and/or the low temperature evaporator 7. If cooling is required, the controller 40 sends an activation signal to the compressor drive unit 33 to activate the compressor.

[33] In addition, if the high temperature storage compartment needs to be cooled off, the controller 40 sends an activation command to the fan drive unit 31 to activate the high temperature fan 4. Likewise, if the low temperature storage compartment needs to be cooled off, the controller 40 sends an activation command to the fan drive unit 31 to activate the low temperature fan 5. In this manner, heat exchange can be performed readily and effectively to cool the items stored in the storage compartment(s) quickly.

[34] Moreover, the controller 40 receives a defrost signal from the defrost sensor 23 and compares the current conditions of an evaporator of interest with the prestored defrost conditions (e.g., reference voltage, reference current, etc.). If defrost needs to be initiated, the controller 40 sends an activation signal to the defrost heater 24 to get rid of frost on the evaporator.

[35] FIG. 4 graphically explains a control method of a parallel-type refrigerator according to the present invention. When the high temperature storage compartment requires cooling (tθ-tl, t4-t5), the controller 40 sends a signal to the valve drive unit 31 for adjusting the valve 3 to direct a flow of refrigerants towards the high temperature evaporator 6. When the low temperature storage compartment requires cooling (t2-t3, t6-t7), the controller 40 sends a signal to the valve drive unit 31 for adjusting the valve 3 to direct a flow of refrigerants towards the low temperature evaporator 7.

[36] When cooling of the high temperature storage compartment has ended (tl, t5), the controller 40 does not send any particular signal to the valve drive unit 31 , thereby letting the valve 3 stay in a position to direct refrigerants towards the high temperature evaporator 6. However, when cooling of the low temperature storage compartment has ended (t3, t7), the controller 40 sends a signal to the valve drive unit 31, thereby adjusting the valve 3 to a position to direct refrigerants towards the high temperature evaporator 6. When the valve 3 is controlled by the controller 40, there are certain advantages, as compared with the prior art.

[37] That is, some time between the end of cooling in the low temperature storage compartment and the initiation of cooling of the high temperature storage compartment (i.e. t3-t4 in FIG. 4), the compressor 1 is deactivated and refrigerants are thus fed to the evaporator. At this time, unlike with the prior art control methods, the valve with the present invention control method directs refrigerants towards the high temperature evaporator 6 and blocks the flow of refrigerants towards the low temperature evaporator 7. Therefore, when cooling of the high temperature storage compartment is initiated (t4 in FIG. 4), a certain amount of refrigerants is already present in the high temperature evaporator 6. That is, when cooling of the high temperature storage compartment initiates, the residual amount of refrigerants in the low temperature evaporator decreases. The valve, which is adjusted to a position to direct a flow of refrigerants towards the high temperature evaporator 6, stays in that position until the low temperature storage compartment requires cooling (t6 in FIG. 4).

[38] FIG. 5 is a flow chart explaining a control method of a refrigerator according to the present invention.

[39] In step S 11 , if it is decided that a cooling cycle needs to be performed, the next step

S12 proceeds; if it is decided that a cooling cycle does not need to be performed, the decision step S 11 is repeated until the cooling cycle is required. The controller 40 decides whether a cooling cycle needs to be performed by checking if a temperature sensed by the temperature sensor 21 is lower than a reference temperature.

[40] In step S 12, if a high temperature section needs to be cooled off, step S 16 is carried out; if a low temperature section needs to be cooled off, step S13 is carried out.

[41] In step S 13, since the low temperature section needs to be cooled off, the controller

40 sends a signal to the valve drive unit 32, thereby adjusting the valve 3 to a position to direct refrigerants towards the low temperature evaporator 7.

[42] In step S 14, the controller decides whether cooling has been completed and if so, step S15 is carried out. If cooling has not been completed, however, step S 14 is repeatedly carried out until cooling is completed. A decision on whether cooling has been completed can be made as follows. For example, the controller 40 receives information on a temperature sensed by the temperature sensor 21 and checks if the sensed temperature in the low temperature storage compartment is above the reference temperature, or it checks if a preset amount of time has elapsed after the initiation of cooling. Particularly, it should be noted that makng a decision based on whether the preset amount of time has passed is possible by means of a timer incorporated into the controller 40.

[43] In step S 15, since a cooling operation on the low temperature section has been completed (t3 in FIG. 4), the controller 40 sends a signal to the valve drive unit 32, thereby adjusting the valve to a position to direct refrigerants towards the high temperature evaporator 6. This is because if the operation of a cooling cycle is stopped at the end of a cooling operation on the low temperature section, refrigerants are stacked in the low temperature storage compartment and they may impede smooth cooling operation on the high temperature section later. When cooling is over (t3-t4 in FIG. 4), the compressor 1 is also deactivated so refrigerants move through the condenser. By adjusting the valve, the refrigerants having been fed into the compressor 1 through the low temperature evaporator 7 now flow towards the high temperature evaporator 6 because the valve 3 is open only towards the high temperature section. Therefore, even when cooling of the high temperature storage compartment initiates (t5 in FIG. 4), a smaller amount of refrigerants is left over in the low temperature storage compartment.

[44] In step S 16, since the high temperature section needs to be cooled off, refrigerants must be supplied to the high temperature evaporator 6. Thus, the controller 40 sends a signal to the valve drive unit 32, thereby adjusting the valve to a position to direct refrigerants towards the high temperature evaporator 6.

[45] In step S 17, the controller 40 checks if cooling has been completed and if so, the cooling cycle is ended. If cooling has not been completed, however, step S 17 is repeatedly carried out until cooling is completed. A decision on whether cooling has been completed can be made as follows. For example, the controller 40 receives information on a temperature sensed by the temperature sensor 21 to check if the sensed temperature in the high temperature storage compartment is above the reference temperature, or it checks if a preset amount of time has elapsed after the initiation of cooling. As noted earlier, it should be noted that making a decision based on whether the preset amount of time has passed is possible by means of a timer incorporated into the controller 40.

[46] Based on the control method explained with reference to FIG. 5, the following now explains the operation of the valve, with a cooling cycle as in FIG. 2 being performed.

[47] From t0 to tl, the high temperature storage compartment needs to be cooled off, so the controller 40 activates a cooling cycle and carries out step S 16 through steps SI l and S12 and adjusts the valve to a position to direct refrigerants towards the high temperature evaporator 6. As such, refrigerants flow from the condenser, via the valve, and to the heat exchanger of the high temperature storage compartment 6. Even if it seems cooling has come to an end through step S 17, the valve stays in the position to direct refrigerants towards the high temperature evaporator 6.

[48] From tl to t2, the cooling cycle is not performed. Thus, the control method halts or circulates in step SI l. Even then, the valve remains in its position unchanged.

[49] From t2 to t3, the low temperature storage compartment needs to be cooled off, so the controller 40 activates a cooling cycle and carries out step S 13 through steps SI l and S 12, and adjusts the valve to a position to direct refrigerants towards the low temperature evaporator 7. As such, refrigerants flow from the condenser, via the valve, and to the heat exchanger of the low temperature storage compartment 7. Even if it seems cooling has come to an end through step S 14, the valve moves to the position to direct refrigerants towards the high temperature evaporator 6.

[50] From t3 to t4, the cooling cycle is not performed. Thus, the control method halts or circulates in step SI l. Even then, the valve remains in its position unchanged.

[51] From t4 to t5, the valve is adjusted to the position to direct refrigerants towards the high temperature evaporator 6, just it has been so from t0 to tl. Also, it should be noted that the valve adjustment carried out from t5 to t6 is same as that from tl to t2, and that the valve adjustment carried out from t6 to t7 is same as that from t2 to G.

[52] The present invention has been described in detail with reference to the embodiments and the attached drawings. However, the scope of the present invention is not limited to the embodiments and the drawings, but defined by the appended claims.

Claims

[1] In a refrigerator comprising a first storage compartment for storing an item, a second storage compartment for storing an item at a lower temperature than the first storage compartment, a cooling cycle including a compressor, a condenser for condensing a refrigerant from the compressor, a valve for directing the refrigerant from the condenser to first and second evaporators, with the first and second evaporators evaporating supplied refrigerants to cool the first and second storage compartments, respectively, and first and second fans for circulating cool air from the first and second evaporators, respectively, and a controller for controlling the first and second fans, the valve and the compressor, a control method of the refrigerator comprising: a first step of activating the compressor if cooling of the second storage compartment is required, and adjusting the valve to direct a refrigerant towards the second evaporator; and a second step of adjusting the valve to direct refrigerants towards the first evaporator, if the cooling of the second storage compartment is completed.

[2] The control method according to claim 1, wherein the second step includes deactivating the compressor after the cooling of the second storage compartment is completed.

[3] The control method according to claim 2, wherein the second step includes adjusting the valve to an open position only towards the first evaporator.

[4] The control method according to claim 2 or claim 3, wherein the second step includes reactivating the compressor, if the first storage compartment needs to be cooled off after the valve has been adjusted, and then adjusting the valve to a position to direct a refrigerant towards the first evaporator.

[5] The control method according to one of claims 1 through 4, wherein the first step includes deciding whether the second storage compartment needs to be cooled off.

[6] A refrigerator, comprising: a first storage compartment for storing an item and a second storage compartment for storing an item at a lower temperature than the first storage compartment; a cooling cycle including a compressor, a condenser for condensing a refrigerant from the compressor, a valve for directing the refrigerant from the condenser to first and second evaporators, with the first and second evaporators evaporating supplied refrigerants to cool the first and second storage compartments, respectively, first and second fans for circulating cool air from the first and second evaporators, respectively; and a controller for performing a cooling operation on each of the first and second storage compartments and adjusting the valve, after cooling of the second storage compartment is completed, to direct refrigerants towards the first evaporator.

[7] The refrigerator according to claim 6, comprising: sensing units for sensing temperatures of the first and second evaporators.

[8] The refrigerator according to claim 6, wherein the controller comprises: a timer for checkng the completion of cooling.

[9] The refrigerator according to one of claims 6 through 8, wherein the controller deactivates the operation of the compressor after cooling of the second storage compartment is completed.

[10] The refrigerator according to claim 9, wherein the valve is in an open position only towards the first evaporator.

[11] The refrigerator according to claim 9 or claim 10, wherein if the controller decides that the first storage compartment needs to be cooled off after having deactivated the operation of the compressor, the controller reactivates the compressor and adjusts the valve to a position to supply a refrigerant towards the first evaporator.

[12] The refrigerator according to one of claims 6 through 11, comprising: a defrost sensor for sensing whether the first evaporator and/or the second evaporator is frosted.

[13] The refrigerator according to claim 12, wherein the defrost sensor is a sensor having a variable resistance in response to temperatures in high- and low- temperature evaporators.

[14] The refrigerator according to claim 12 or claim 13, comprising: a defrost heater for applying heat to the evaporators to get rid of frost generated thereon.