EP2101128B1

EP2101128B1 - Method of controlling ice making assembly for refrigerator

Info

Publication number: EP2101128B1
Application number: EP09002660.0A
Authority: EP
Inventors: Young Jin Kim; Tae Hee Lee; Hong Hee Park; Ho Youn Lee; Joon Hwan Oh
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2008-03-10
Filing date: 2009-02-25
Publication date: 2018-11-07
Anticipated expiration: 2029-02-25
Also published as: CN101893360B; EP2101128A3; CN101893360A; US20090223230A1; CN101532761A; EP2101128A2; KR20090096787A; KR101457691B1

Description

BACKGROUND

The present disclosure relates to a method of controlling an ice making assembly for a refrigerator for making transparent ice.
Refrigerators are domestic appliances used for storing foods in a refrigerated or frozen environment.
Recently, various kinds of refrigerators have been introduced into the market. Examples of recent refrigerators include: a side-by-side type refrigerator in which a refrigerator compartment and a freezer compartment are disposed in the left and right sides; a bottom-freezer type refrigerator in which a refrigerator compartment is disposed above a freezer compartment; and a top-mount type refrigerator in which a refrigerator compartment is disposed under a freezer compartment.
Furthermore, many of recently introduced refrigerators have a structure that allows a user to access food or drink disposed inside a refrigerator compartment through an alternate access point without having to open a primary refrigerator compartment door. A compressor, a condenser, and an expansion member are disposed inside a refrigerator, and an evaporator is disposed on the backside of a refrigerator main body, as refrigeration-cycle components of the refrigerator.
In addition, an ice making assembly can be provided inside the refrigerator. The ice making assembly may be mounted in a freezer compartment, a refrigerator compartment, a freezer compartment door, or a refrigerator compartment door.
To satisfy consumers' increasing demands for transparent ice, much research has been conducted on ice making assemblies that can provide transparent ice.
US 5,297,394 A describes an ice maker for use in a domestic refrigerator for making clear ice bodies. The ice maker comprises a support arranged to have an ice body formed thereon. The support is refrigerated to a below-freezing temperature and a container adapted to hold a body of water is moved to move liquid water contained therein uniformly about the support suitable to cause a clear substantially symmetrical ice body to build up outwardly on the refrigerated support.
JP 2002 340455A relates to a refrigerator equipped with an automatic ice-machine and its control method, capable of supplying timely ice and shortening the ice-making time for making ice quickly in case that the quantity of ice storage is small.
KR 2007 0119271 A relates to a refrigerator and method for ice-making using the same to emit air dissolved in water to the outside constantly through the unfrozen surface of water by heating the surface of water contained in an ice-making tray, thereby making transparent ice with simple formation. The refrigerator has a main body having a freezing compartment and an ice-maker installed in the freezing compartment, the ice-maker including an ice-making tray containing water to be frozen, an ejector shaft installed rotatively at an upper part of the ice-making tray for ice separation and at least one or more heaters installed under the ejector's shaft to heat the surface of water contained in the ice-making tray.

SUMMARY

The disclosed embodiments provide a method of controlling an ice making assembly for a refrigerator that can produce transparent ice.
The disclosed embodiments provide methods of controlling an ice making assembly for a refrigerator.
The objects are solved by the features of the independent claims.
According to one example, there is provided a method of controlling an ice making assembly for a refrigerator, the method including: selecting an ice making mode; supplying water to an ice recess formed in a tray so as to immerse a rod configured to take heat from the water; intermittently operating a heater disposed at the tray to maintain the tray at a temperature higher than a freezing temperature; and controlling an operation of a cooling fan configured to supply cooling air so as to cool the rod.
According to an other example, there is provided a method of controlling an ice making assembly for a refrigerator, the method including: selecting an ice making mode; supplying water to an ice recess formed in a tray so as to immerse a rod configured to take heat from the water; intermittently operating a heater disposed at the tray to maintain the tray at a temperature higher than a freezing temperature; and controlling an operation of an ice ejecting heater configured to heat the rod so as to decrease a temperature of the rod with time.
According to the method of controlling the ice making assembly, transparent ice can be made in an ice making compartment that is kept at a temperature lower than 0°C.
That is, the tray is kept at a temperature higher than 0°C during an ice making operation to freeze water slowly and to ensure that the water freezes in a direction starting from the rod toward the inner surface of the ice recess. Therefore, while the freezing of the water proceeds, air dissolved in the water can escape from the water before the air is trapped in the ice. The resulting ice that is made is thus transparent.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGs. 1 and 2 are perspective views illustrating an ice making assembly structure for a refrigerator according to an embodiment of the invention.
FIG. 3 is a perspective view illustrating an ice making assembly according to an embodiment of the invention.
FIG. 4 is a perspective view illustrating the ice making assembly, according to an embodiment of the invention, just before ice is transferred to a container.
FIG. 5 is a perspective view illustrating a tray of the ice making assembly according to an embodiment of the invention.
FIG. 6 is a sectional view illustrating a process of making transparent ice in the ice making assembly according to an embodiment of the invention.
FIG. 7 is a flowchart depicting a method of controlling the temperature of a tray of an ice making assembly according to an embodiment of the invention.
FIG. 8 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a first embodiment of the invention.
FIG. 9 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a second embodiment of the invention.
FIG. 10 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a third embodiment of the invention.
FIG. 11 is a graph illustrating the temperature of a rod when a method of controlling an ice making assembly is performed according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an ice making assembly for a refrigerator will be described in detail according to embodiments of the present disclosure with reference to the accompanying drawings,
In the following description, an ice making assembly may be mounted at a freezer compartment door. However, the ice making assembly can be mounted at other places such as a freezer compartment, a refrigerator compartment, and a refrigerator compartment door and still be within the scope of the invention.
FIGs. 1 and 2 are perspective views illustrating an ice making assembly structure for a refrigerator according to an embodiment of the invention.
Referring to FIGs. 1 and 2, an ice making assembly 20 of the exemplary embodiment may be mounted on the backside of a door 10, and the backside of the door 10 may be recessed to form an ice making space 11 that accommodates the ice making assembly 20. A cooling air supply hole 111 (FIG. 2) may be formed at a side of the ice making space 11 to allow inflow of cooling air from an evaporator (not shown), and a cooling air discharge hole 112 (FIG. 2) may be formed in the side of the ice making space 11 to allow the cooling air from the ice making space 11 to flow back to the evaporator.
In detail, the ice making assembly 20 may be mounted at an upper portion of the ice making space 11, and a container 30 may be mounted under the ice making assembly 20 to store ice made by the ice making assembly 20. The ice making assembly 20 may be protected by an ice making cover 31. The ice making cover 31 may also provide guidance for the ice separated from the ice making assembly 20 so that it follows a path directly to the container 30.
FIG. 3 is a perspective view illustrating the ice making assembly 20 according to an embodiment of the invention, and FIG. 4 is a perspective view illustrating the ice making assembly 20, according to an embodiment of the invention, just before ice is transferred to the container 30.
Referring to FIGs. 3 and 4, the ice making assembly 20 may include: a tray 21 having a plurality of ice recesses 211 for making ice in a predetermined shape; a plurality of fins 24 stacked above the tray 21 and capable of vertical and rotational movement; a plurality of rods 23 configured to be inserted into the ice recesses 211 through the fins 24; an ice ejecting heater 25 may be provided as the lowermost fin of the plurality of fins 24; a supporting plate 27 configured to support the ice ejecting heater 25, the remainder of the plurality of fins 24, and the rods 23 as one unit; a water supply part 26 disposed at an end of the tray 21; and a control boxy 28 disposed at another end of the tray 21.
In detail, a heater (not shown) may be mounted at the bottom of the tray 21 to maintain the temperature of the tray 21 at a temperature above freezing. A supporting lever 271 may extend from a front end of the supporting plate 27, and a hinge 272 may be disposed at an end of the supporting plate 27. During an ice making operation, as shown in FIG. 4, ice cubes (I) having a shape corresponding to the shape of the ice recesses 211 are formed around the rods 23.
A cam 29 coupled to a driving motor are disposed inside the control box 28. The driving motor drives a rotational movement of the cam 29. The hinge 272 may be coupled to the cam 29 so that the hinge 272 can be lifted and rotated by the rotation of the cam 29. The ice ejecting heater 25 may have a plate-like shape and may make contact with the rods 23. Alternatively, the ice ejecting heater 25 may be buried in the rods 23. The supporting plate 27 may act to close an open-top of the tray 21 (see FIG. 3) such that water supplied to the tray 21 is indirectly cooled by cooling air that is supplied to the ice making space 11 and flows about fins 24 and rods 23.
Hereinafter, ice making and ice ejecting operations of the ice making assembly 20 will be described.
First, the heater attached to the tray 21 is operated to maintain the tray 21 at a temperature higher than 0°C so as to make transparent ice in the ice making assembly 20.
In the related art when water is rapidly frozen by cooling air supplied from an evaporator, air dissolved in the water cannot escape from the water before it freezes. Thus, when water is frozen together with gas that is trapped inside the water, the resulting ice will not be transparent.
However, in the ice making assembly 20 of the disclosed exemplary embodiments, the tray 21 is kept at a temperature above freezing so that the water freezes slowly. The air in the water is then able to escape before the water is completely frozen. Thus resulting in transparent ice, which is preferred by the user.
Once the rods 23 are inserted in the ice recesses 211 of the tray 21, water is supplied to the tray 21, and a freezing operation is started after the supply of water is completed. The freezing operation is started by supplying cooling air to the ice making space 11. Then, the temperature of the fins 24 is reduced to below freezing by convection heat transfer with the supplied cooling air. The temperature of the rods 23 is also reduced to below freezing by conduction heat transfer with the fins 24. Portions of the rods 23 inserted in the ice recesses 211 are submerged in the water. Therefore, the water is gradually frozen starting from a region closest to the rods 23, and the frozen region of the water becomes attached to the rods 23. Then, the freezing of the water further proceeds outwardly from a region closest to the rods 23 toward a region close to the inner surfaces of the ice recesses 211.
After the water is completely frozen, the cam 29 is rotated to move the rods 23, and the ice cubes formed thereon, vertically upward out of the ice recesses 211. In the exemplary embodiment, after the ice cubes (I) are completely removed from the ice recesses 211, the cam 29 is further rotated to rotate the rods 23 at a predetermined angle so that the ice cubes (I) can slip off of the rods 23 and fall into an ice container 30.
Whether freezing of the water is completed may be determined by several methods. A first method, according to the present invention, involves monitoring time lapsed while the water is freezing. If a predetermined amount of time passes after the start of the freezing, it may be determined that the freezing is completed.
Another method of determining the completion of freezing not being part of the present invention, involves lifting the rods 23, via cam 29, out of the recesses 211, and detecting an amount of water remaining in the recesses 211. The rods 23 may be lifted to a predetermined height after a predetermined amount of time has passed from the start of freezing. The predetermined height may be a height at which ice attached to the rods 23 is not yet fully separated from the ice recesses 211. Once the rods 23 are lifted, the amount of water remaining in the ice recesses 21 may be detected. The amount of unfrozen water remaining in the ice recesses 211 can be detected, for example, using a water level sensor (not shown) mounted on the tray 21. If the amount of unfrozen water remaining in the ice recesses 211 is equal to or less than a predetermined amount, it may be determined that the freezing is completed. On the other hand, if the amount of unfrozen water remaining in the ice recesses 211 is greater than the predetermined amount, the rods 23 may be moved down to their original positions to continue freezing the water. The water sensor will be described later with reference to the accompanying drawings.
As described above, after the freezing of the water is completed, the cam 29 may be rotated such that it moves the rods 23, and the ice cubes formed thereon, vertically upward out of the ice recesses 211. After ice cubes (I) are completely removed from the ice recesses 211, the cam 29 may be further rotated to effect rotation of the rods 23. More specifically, the hinge 272 may be rotated by the cam 29 to rotate the rods 23 at a predetermined angle. Once the rods 23 are rotated to a predetermined angle as shown in FIG. 4, the ice ejecting heater 25 may be operated. When the ice ejecting heater 25 is operated, the temperature of the rods 23 is increased, and thus the ice cubes (I) are separated from the rods 23. The separated ice cubes (I) may thus fall into the container 30.
FIG. 5 is a perspective view illustrating the tray 21 of the ice making assembly 20 according to an embodiment of the invention.
As illustrated in FIG. 5, the ice recesses 211 are arranged in the tray 21 of the ice making assembly 20. Grooves 213 having a predetermined depth are formed between the ice recesses 211. Water can travel between neighboring ice recesses 211 through the grooves 213. Bottoms of the grooves 213 are spaced apart from bottoms of the ice recesses 211.
A guide 212 may be formed at an end portion of the tray 21 to guide water supplied from the water supply part 26 to the tray 21 and to the ice recesses 211. Water may be supplied to the ice recesses 211 closest to the guide 212 and may gradually travel to the ice recess 211 farthest from the guide 212.
A water level sensor 40 may be mounted at a side of the ice recess 211 farthest from the guide 212, e.g., at a side of the ice recess located at an end of the tray 21 opposite to the guide 212. Further, a temperature sensor 50 may be mounted at a side of the tray 21. The temperature sensor 50 may provide feedback to a subsystem adapted to maintain the tray 21 at a constant temperature. A tray heater (not shown) may be installed at the tray 21. The tray heater may be installed at the tray 21 in an embedded or attached manner.
FIG. 6 is a sectional view illustrating a process of making transparent ice in the ice making assembly 20 according to an embodiment of the invention.
Referring to FIG. 6, in the exemplary embodiment, a tray heater 60 may be installed in the tray 21 of the ice making assembly 20. After the rod 23 is moved down to a preset position, the ice recess 211 is filled with water. Alternatively, the rod 23 can be moved down to the preset position after the ice recess 211 is filled with water.
Once the rods 23 are in position, and the ice recesses contain a sufficient volume of water, an ice making operation can begin. The fins 24 are cooled by cooling air that is circulated to cool the tray 21 and rods 23 to below freezing by convection heat exchange with the fins 24. When the temperature of the rod 23 drops below freezing, ice is formed around the rod 23. At this point, the tray heater 60 operates to maintain the tray 21 at a temperature above 0°C. According to an exemplary embodiment, the tray 21 may be kept at a temperature in the range of 1°C to 2°C. According to Henry's Law, the solubility of gas in water is reduced as the temperature of the water increases. Therefore, air present in the water can be removed from the water as it freezes by operating the tray heater 60. At the same time, ice grows from the surface of the rod 23.
During the ice making process, ice forms outwardly from the surface of rod 23 while the tray 21 is kept at a temperature above freezing. Therefore, ice cannot form at the inner surface of the tray 21. In other words, ice cannot form on the inner surface of an ice recess 211. Accordingly, when the ice making operation is completed a predetermined amount of water may remain in the ice recess 211. The removal of the ice cubes from the tray 21 is facilitated in an embodiment where water remains in an unfrozen state just adjacent to the inner surface of the ice recess 211.
A rod temperature sensor 70 may be disposed in the rod 23. Thus, when the rod 23 is heated by the ice ejecting heater 25 (FIG. 4) during an ice ejecting operation, the temperature increase of the rod 23 is controlled to reach a set temperature. It is also envisioned that during an ice making operation, the rod 23 may be heated to temporarily increase the temperature of water present in the tray 21, so as to allow air trapped in the water to escape.
For example, in another method, a cooling fan (not shown), configured to supply cooling air to the inside of the ice making space 11, is controlled. In yet another method, the ice ejecting heater 25, configured to heat the rod 23, and the cooling fan are both simultaneously operated and controlled. A method of controlling the temperature of water filled in the tray 21 for making transparent ice will now be described with reference to a flowchart.
FIG. 7 is a flowchart depicting a method of controlling the temperature of a tray of an ice making assembly according to an embodiment of the invention
Referring to FIG. 7, an ice making mode may be started by a user or a control unit (see e.g., ref. 45 of FIG. 3) associated with the refrigerator (operation S11) in general or the ice making assembly in particular.
By way of example, the ice making mode can be initiated by the control unit 45 when an automatic ice making operation is necessary; for example, when a low amount of ice in ice container 30 is detected.
After the ice making mode begins, or even continuously, the control unit 45 receives a signal from a temperature sensor, such as temperature sensor 50 of FIG. 5, to determine the temperature of the tray 21. The control unit 45 determines whether the temperature T of the tray 21 is at a predetermined temperature T₀. The control unit 45 determines whether the tray temperature T is lower or higher than the predetermined temperature T₀ (operation S12).
If the tray temperature T is lower than the predetermined temperature T₀, the tray heater 60 may be turned on to heat the tray 21 (operation S13). On the other hand, if the tray temperature T is equal to or greater than the predetermined temperature T₀, the tray heater 60 may be turned off (operation S14). Here, turning-off of the tray heater 60 includes the case where the tray heater 60 is previously turned off and kept in the turned-off state.
As the tray heater 60 is controlled as described above, the control unit 45 may also determine whether ice making is completed (operation S15). An exemplary method of determining whether ice making is complete is as discussed above.
If it is determined that ice making is complete, the ice making mode is turned off (operation S16) to complete the ice making operation. On the other hand, if it is determined that ice making is not completed, operations S12, S13, and S14 may be repeated. Thus, the on-off control of the tray heater 60 continues until the ice is satisfactorily formed.
By using the above-described control method, the tray 21 can be kept at a temperature above freezing temperature while ice is forming around the control rod 23, thus resulting in transparent ice.
FIG. 8 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a first embodiment of the invention.
Referring to FIG. 8, in the exemplary embodiment, the temperature of water supplied to the tray 21 is controlled by controlling the operation of a fan during an ice making operation.
In detail, according to the above-described gas solubility properties, air contained in water may be trapped in the water as it freezes if the temperature of the water drops too quickly. To prevent this, the temperature of the water is temporarily raised to allow the air to escape.
First, when an ice making mode is turned on (operation S21), water is first supplied (operation S22). Before an ice making operation begins after the water supply operation, a control unit 45 determines whether the measured temperature T of the rod 23 is equal to or greater than a first predetermined temperature T1 (operation S24). Here, the temperature T of the rod 23 may be the surface temperature of the rod 23, which may be detected using the rod temperature sensor 70 (FIG. 6). If it is determined that the temperature T of the rod 23 is equal to or greater than the first temperature T1, the cooling fan may be turned on to lower the temperature of rod 23 (operation S25). On the other hand, if it is determined that the temperature T of the rod 23 is lower than the first temperature T1, the cooling fan may be turned off (operation S26) to prevent cool air circulation in the ice making space 11. Here, turning-on (S25) or turning-off (S26) includes the situation where the cooling fan may be previously turned on or off and is maintained in the turned-on or turned-off state, respectively. For example, if it is determined that the rod temperature T is equal to or greater than the first temperature T1 and the cooling fan is in an turned-on state, the cooling fan may simply be left in the turned-on state.
Once the cooling fan operation has been determined, the control unit determines whether ice making time (t) has reached a first set time t1 (operation S27).
In detail, if it is determined that the ice making time, e.g., the time passed since the ice-making operation began (t), has not reached the first set time t1, the procedure may go back to operation S24. On the other hand, if it is determined that the ice making time (t) has reached the first set time t1, the rod 23 temperature may then be controlled.
More specifically, after the ice making time reaches the first set time t1, it is then determined whether the rod temperature T is equal to or greater than a second predetermined temperature T2 (operation S28). The second predetermined temperature T2 is lower than the first predetermined temperature T1. If it is determined that the rod temperature T is equal to or greater than the second temperature T2, the cooling fan may be turned on (operation S29). Otherwise, the cooling fan may be turned off (operation S30). These operations are generally the same as those operations using the first temperature.
While keeping the rod temperature T below the second temperature T2, it is determined whether the ice making time (t) has reached a second set time t2 (operation S31).
When it is determined that the ice making time (t) reaches the second set time t2, an ice ejecting operation is performed (S32). After the ice ejecting operation, the ice making mode may be turned off (operation S33). If the ice making time (t) has not reached the second set time t2, the procedure will go back to operation S28.
In the first embodiment, a control process may be carried out to make transparent ice using the cooling fan without turning on the ice ejecting heater 25. While the "on/off" control of the cooling fan is discussed above, the speed of the cooling fan can also be controlled depending on the measured temperature of the rod 23. In this situation, a variable speed fan motor may be used.
The temperature of the rod 23 is reduced slowly, in steps, to prevent trapping air in the water as it freezes. In the exemplary embodiment the temperature T of the rod 23 is reduced in two steps, however, three or more steps may be used according to, for example, freezer compartment conditions.
FIG. 9 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a second embodiment.
Referring to FIG. 9, in the exemplary embodiment, the temperature of water supplied to the tray 21 may be controlled via the ice ejecting heater 25. The cooling fan is kept on i.e., continuously operated, while the ice-ejecting heater 25 is controlled to adjust the temperature of rod 23.
First, the ice making mode is initiated (operation S51), water is supplied (operation S52), and the water supply is completed (operation S53) similar to the first embodiment.
After the water supply is completed, the cooling fan is operated to supply and circulate cooling air throughout the ice making space 11 (operation S54). The plurality of fins 24 are cooled by convection heat transfer with the cooling air, and the rod 23 is cooled by conduction heat transfer with the cooled fins 24.
The surface temperature of the rod 23 may be measured by the rod temperature sensor 70 and may be transmitted to the control unit 45. Then, the control unit 45 determines whether the measured rod temperature T is equal to or greater than a first predetermined temperature T1 (operation S55).
In detail, if it is determined that the rod temperature T is equal to or greater than the first temperature T1, the ice ejecting heater 25 is turned off (operation S56). Otherwise, the ice ejecting heater 25 is turned on (operation S57). Here, turning the ice ejecting heater 25 on or off is similar to the above-described "on/off' function of the cooling fan.
After the on/off operation of the ice ejecting heater 25 is determined and a predetermined time has passed, the control unit may determine whether ice making time (t) reaches a first set time t1 (operation S58). If the ice making time (t) has not reach the first set time t1, the procedure goes back to operation S55.
On the other hand, if the ice making time (t) has reached the first set time t1, the temperature T of the rod 23 is then reduced to a temperature lower than the first set temperature T1.
In more detail, once the ice making time (t) reaches the first set time t1, the current rod temperature T may be measured. It is then determined if this measured rod temperature T is equal to or greater than a second predetermined temperature T2 (operation S59). Here, the second temperature T2 is lower than the first set temperature T1. If the rod temperature T is equal to or greater than the second temperature T2, the ice ejecting heater 25 is turned off (operation S60). Conversely, if the rod temperature T is lower than the second set temperature T2, the ice ejecting heater 25 is turned on (operation S61).
Then, it is determined whether the ice making time (t) has reached a second set time t2 (operation S62). This time passage determination is conducted while the temperature T of the rod 23 is maintained at the second set temperature T2.
As illustrated in FIG. 9, if the ice making time (t) has not reached the second set time t2, the procedure goes back to operation S59. Conversely, if the ice making time (t) has reached the second set time t2, an ice ejecting operation is performed (S63). After the ice is ejected, the ice making mode may be turned off (operation S64).
According to the above-described method, the ice ejecting heater 25 is used to control the ice-making environment to make transparent ice. That is, if the rod temperature T is reduced to below a temperature suitable for making transparent ice, the ice ejecting heater 25 is turned on to heat the rod 23. Therefore, the temperature of water filled in the tray 21 may be properly controlled so that air contained in the water can escape as the water freezes.
In the second exemplary embodiment, the temperature of water filled in the tray 21 is adjusted by controlling the ice ejecting heater 25. For example, a voltage applied to the ice ejecting heater 25 can be controlled using a semiconductor switch device, such as a TRIAC or a thyristor. In this case, if the temperature T of the rod 23 is lower than a set temperature T1 or T2, the amplitude of the voltage applied to the ice ejecting heater 25 may be increased to generate more heat. Conversely, if the temperature T is higher than a set temperature the amplitude of the voltage applied to the ice ejecting heater 25 may be reduced to generate less heat. Further, the temperature T of the rod 23 may be steadily (continuously) reduced instead of being reduced in a stepped manner.
FIG. 10 is a flowchart depicting a method of making transparent ice using an ice making assembly according to a third embodiment.
As illustrated in FIG. 10, in the exemplary embodiment, the temperature of water supplied to the tray 21 may be controlled by cooperatively operating the ice ejecting heater 25 and the cooling fan.
First, it is noted that turning on the ice making mode (operation S71), water supply (operation S72), and completion of water supply (operation S73) are performed in the same way as in the first embodiment.
In detail, after water supply is completed, it is determined whether the temperature T of the rod 23 is equal to or greater than a first predetermined temperature T1 (operation S74). If the detected rod temperature T is equal to or greater than the first temperature T1, the cooling fan may be turned on and the ice ejecting heater 25 may be turned off (operation S75). Thus, cooling air may be supplied to the ice making space 11, to cool the rod 23 to the first temperature T1. Conversely, if the rod temperature T is lower than the first temperature T1, the cooling fan may be turned off and the ice ejecting heater 25 may be turned on to keep the rod temperature T at approximately first temperature (operation S76).
While the rod temperature T is maintained at approximately the first temperature T1, as described above, the control unit 45 determines whether the time that passed since the ice making process began, i.e., ice making time (t), has reached a first set time t1 (operation S77). If the ice making time (t) has not reached the first set time t1, the procedure will go back to operation S74.
Conversely, if the ice making time (t) has reached the first set time t1, the temperature T of the rod 23 is reduced to and kept at a temperature lower than the first temperature T1. That is, it is determined whether the rod temperature T is equal to or greater - than a second predetermined temperature T2 (operation S78). Here, the second temperature T2 is less than the first temperature T1.
In detail, if the rod temperature T is equal to or greater than the second temperature T2, the cooling fan may be turned on and the ice ejecting heater 25 may be turned off (operation S79). On the other hand, if the rod temperature T is below the second temperature T2, the cooling fan may be turned off and the ice ejecting heater 25 may be turned on (operation S80). Once the rod temperature T reaches the second temperature T2, the amount of time that has passed, i.e. an ice-making time (t), is compared to a second set time t2. Based on this comparison it is determined whether the ice making time (t) has reached a second set time t2 (operation S81). If the ice making time (t) has not yet reached the second set time t2, the procedure goes back to operation S78.
If the ice making time (t) has reached the second set time t2, the ice making operation is completed and the ice is then ejected (S82). After the ice ejecting operation is complete, the ice making mode is turned off (operation S83). It is noted that for the method described above the temperature T of the rod 23 may be reduced in a stepped manner or in a continuous/gradual manner. For example, if the temperature T of the rod 23 is equal to or greater than a predetermined temperature T1 or T2, the temperature T of the rod 23 can be reduced to the set temperature by increasing the speed of the cooling fan and reducing power to the ice ejecting heater 25. On the other hand, if the temperature T of the 23 is below the predetermined temperature T1 or T2, the temperature T of the rod 23 can be increased to the predetermined temperature T1 or T2 by reducing the speed of the cooling fan and increasing power to the ice ejecting heater 25.
FIG. 11 is a graph depicting the temperature of a rod when a method of controlling an ice making assembly is performed according to an embodiment.
Referring to FIG. 11, according to the controlling methods of the first to third exemplary embodiments, the temperature of the rod 23 may vary as shown in the graph of FIG. 11. In the above-described embodiments, the temperature of the rod 23 may be reduced in two steps; however, the temperature of the rod 23 may be reduced in three or more steps.
As shown in FIG. 11, the temperature of the rod 23 varies slightly around the first temperature T1 for the first set time t1. That is, the average temperature of the rod 23 is kept at approximately at the first temperature T1. After the first set time period t1 has passed, the temperature of the rod 23 is kept at approximately the second set temperature T2 for the second set time period t2 until ice making is completed.
According to the above-described controlling method, water supplied to the tray 21 may be kept at a relatively high temperature during the early stage of an ice making operation so as to allow air contained in the water to escape before the water freezes. Thereafter, the temperature of the rod 23 is reduced to increase the ice forming rate. Accordingly, the generation of opaque ice resulting from a rapid drop in water temperature can be minimized.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments could be devised by those skilled in the art that will fall within the scope of the claims.

Claims

A method of controlling an ice making assembly (20) for a refrigerator, the method comprising:
initiating (S21) an ice making mode;

supplying water to (S22) an ice recess (211) formed in a tray (21), the tray (21) ready to receive a rod (23);

contacting the water with the rod (23) to remove heat from the water;

intermittently operating (S13, S14) a heater (60) disposed at the tray (21) to maintain the tray (21) at a temperature above freezing;

characterized by

detecting (S24) a temperature of the rod (23);

controlling (S25, S26) the operation of a cooling fan to selectively supply cooling air to the rod (23) such that the temperature of the rod (23) is maintained in a first predetermined temperature (T1);

determining (S27) whether an ice making time (t) has reached a first set time (t1);

controlling (S29, S30) the operation of the cooling fan to selectively supply cooling air to the rod (23) such that the temperature of the rod (23) is maintained below a second predetermined temperature (T2) which is lower than the first predetermined temperature (T1), when it is determined that the ice making time (t) has reached the first set time (t1);

determining (S31) whether the ice making time (t) has reached a second set time (t2) while keeping the temperature of the rod (23) below the second predetermined temperature (T2); and

performing (S32) an ice ejecting operation when it is determined that the ice making time (t1) has reached the second set time (t2).
The method according to claim 1, wherein an ice ejecting heater (25) is maintained in a turned-off state until an ice making operation is completed, and is turned on for an ice ejecting operation.
The method according to claim 1 or 2, wherein the cooling fan is intermittently or selectively turned on (S25, S29) and off (S26, S30) to maintain the rod (23) at the first predetermined temperature (T1) or second predetermined temperature (T2) during the ice making operation.
The method according to claim 1, 2 or 3, wherein a rotation speed of the cooling fan is increased or decreased to maintain the rod (23) at a predetermined temperature while ice is forming in the ice tray (21).
The method according to any one of the preceding claims, wherein a temperature of the rod (23) is steadily and continuously decreased during an ice making operation.
The method according to any one of the preceding claims, wherein a temperature of the rod (23) is decreased in a step-wise manner during an ice making operation.
The method according to any one of the preceding claims, wherein a temperature of the rod (23) is maintained at a temperature below freezing while the temperature of the tray (21) is maintained at a temperature above freezing.
A method of controlling an ice making assembly for a refrigerator, the method comprising:
initiating (S51) an ice making mode;

supplying (S52) water to an ice recess (211) formed in a tray (21), the tray (21) ready to receive a rod (23);

contacting the water with the rod (23) to remove heat from the water;

intermittently operating (S13, S14) a heater disposed at the tray (23) to maintain the tray (21) at a temperature above freezing; and

driving (S54) a cooling fan to cool the rod (23);

characterized by

controlling (S56, S57) an operation of an ice ejecting heater (25), which heats the rod (23), such that the temperature of the rod (23) is maintained in a first predetermined temperature (T1);

determining (S58) whether an ice making time (t) has reached a first set time (t1);

controlling (S60, S61) an operation of the ice ejecting heater (25), which heats the rod (23), such that the temperature of the rod (23) is maintained in a second predetermined temperature (T2) which is lower than the first predetermined temperature (T1), when it is determined that the ice making time (t) has reached the first set time (t1), so as to gradually decrease a temperature of the rod (23);

determining (S62) whether the ice making time (t) has reached a second set time (t2) while the temperature of the rod (23) is maintained at the second predetermined temperature (T2); and

performing (S63) an ice ejecting operation when it is determined that the ice making time (t1) has reached the second set time (t2).
The method according to claim 8, wherein a cooling fan is set to run until an ice making operation is completed.
The method according to claim 8, wherein the ice ejecting heater (25) is selectively turned on and off to maintain the rod (23) at the first predetermined temperature (T1) or the second predetermined temperature (T2) during an ice making operation.
The method according to claim 8, wherein a voltage applied to the ice ejecting heater (25) is increased or decreased to maintain the rod (23) at a predetermined temperature (T3, T2) during an ice making operation.
The method according to claim 11, wherein the voltage applied to the ice ejecting heater (25) is increased or decreased by a semiconductor switch device.
The method according to claim 8, wherein the temperature of the rod (23) is steadily and continuously decreased from the first predetermined temperature (T1) to the second predetermined temperature (T2) during the ice making operation.
The method according to any one of claim 8 to 13, wherein the temperature of the rod (23) is decreased in a step-wise manner from the first predetermined temperature (T1) to the second predetermined temperature (T2) during the ice making operation.