US20070227164A1

US20070227164A1 - Automatic icemaker

Info

Publication number: US20070227164A1
Application number: US11/724,254
Authority: US
Inventors: Hideaki Ito; Naotaka Sasaki; Kenji Sugaya
Original assignee: Nidec Servo Corp
Current assignee: Nidec Advanced Motor Corp
Priority date: 2006-04-04
Filing date: 2007-03-15
Publication date: 2007-10-04
Also published as: JP2007278548A; JP4224573B2; US20110023502A1

Abstract

An automatic icemaker according to the present invention is capable of being installed in a freezing compartment and automatically making and discharging ice cubes, the automatic ice-making comprising at least one ice-making tray having a plurality of small ice-making compartments, partitions disposed between respective adjacent small ice-making compartments, and groove-shaped water-passage channels formed in portions of the partitions which are offset from centers of the partitions, and a rotating device for rotating the ice-making tray, wherein water is supplied after the ice-making tray is inclined at a water supply angle less than a water filling angle in such a direction that the water passage channels face downward.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an automatic icemaker which is provided in a refrigerator, and designed such that it repeatedly carries out a water feeding operation, an ice making operation and an ice discharging operation according to a predetermined sequence, and automatically makes ice cubes.
2. Description of the Prior Art
In a conventional automatic icemaker, a groove-shaped water-passage channels are formed in partitions between respective adjacent small ice-making compartments of an ice-making tray in order that water supplied to the ice-making tray from above the ice-making tray can be equally spread into respective small ice-making compartments of the ice-making tray. However, when ice cubes formed in the small ice-making compartments are to be discharged from the ice-making tray, adjacent ice cubes in the small ice-making compartments are freezingly connected to each other through ice formed in the water passage channels. This contributes to falling of the dischargeability of the ice cubes and users' convenience.
For this reason, it is conceivable that the groove-shaped water passage channels are formed in portions of the partitions between the respective adjacent small ice-making compartments which are offset from centers of the partitions, and the ice-making tray is inclined at a predetermined angle, which allows the water to be equally spread into the respective small ice-making compartments, namely, at a water filling angle, and the supply of the water to the ice-making tray is then carried out.
However, when the supply of the water is carried out in the condition where the ice-making tray is inclined at the water filling angle, the water runs along walls of the small ice-making compartments and spills out of the ice-making tray.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an automatic icemaker which is capable of causing water supplied to an ice-making tray from above the ice-making tray to be equally spread into respective small ice-making compartments of the ice-making tray, does not allow adjacent ice cubes formed in the small ice-making compartments to be freezingly connected to each other through ice formed in water passage channels when the ice cubes are to be discharged from the ice-making tray, and does not allow the water to spill out of the ice-making tray at the time of the water supply.
In accordance with one aspect of the present invention, there is provided an automatic icemaker which is capable of being installed in a freezing compartment and automatically making and discharging ice cubes, the automatic icemaker comprising at least one ice-making tray having a plurality of small ice-making compartments, partitions disposed between respective adjacent small ice-making compartments, and groove-shaped water-passage channels formed in portions of the partitions which are offset from centers of the partitions, and a rotating device for rotating the ice-making tray, wherein water is supplied after the ice-making tray is inclined at a water supply angle less than a water filling angle in such a direction that the water passage channels face downward.
According to an another aspect of the present invention, there is provided an automatic icemaker which is capable of being installed in a freezing compartment and automatically making and discharging ice cubes, the automatic icemaker comprising at least one ice-making tray having a plurality of small ice-making compartments, partitions disposed between respective adjacent small ice-making compartments, and groove-shaped water-passage channels formed in portions of the partitions which are offset from centers of the partitions, and a rotating device for rotating the ice-making tray, wherein water is supplied while the ice-making tray is rotated in such a direction that the water-passage channels face downward, according to a quantity of the water stored in the small ice-making compartments by the supply of the water.
In these automatic icemakers, the groove-shaped water-passage channels are formed in the portions of the partitions between the respective small ice-making compartments which are offset from the centers of the partitions, so that the water can be equally spread into the respective small ice-making compartments and adjacent ice cubes formed in the small ice-making compartments are not freezingly connected to one another through ice formed in the water passage channels when the ice cubes are to be discharged from the ice-making tray. Moreover, the ice-making tray is inclined at the water supply angle in such a direction that the water passage channels face downward, and the supply of the water to the ice-making tray is then carried out, or the supply of the water is carried out while causing the ice-making tray to be rotated in such a direction that the water passage channels face downward, according to the quantity of the water stored in the small ice-making compartments by the supply of the water, so that even if the flow of the water is strong, it is possible to supply the water to the ice-making tray without allowing the water to spill out of the ice-making tray.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of an automatic icemaker according to an embodiment of the present invention;

FIG. 2 is a schematic front sectional view of the automatic icemaker shown in FIG. 1;

FIG. 3 is a schematic enlarged sectional view of the automatic icemaker, taken along a line A-A in FIG. 1;

FIG. 4 is a system block diagram of the automatic icemaker shown in FIGS. 1 to 3;

FIG. 5 is a functional block diagram of a microprocessor of the automatic icemaker shown in FIGS. 1 to 4;

FIG. 6 is a flow chart which is of assistance in explaining the operation of the automatic icemaker shown in FIGS. 1 to 4;

FIGS. 7A, 7B and 7C are each a view which is assistance in explaining the operation of the automatic icemaker shown in FIGS. 1 to 4;

FIG. 8 is a functional block diagram of a microprocessor of an automatic icemaker according to another embodiment of the present invention; and

FIG. 9 is a flow chart which is of assistance in explaining the operation of the automatic icemaker having the microprocessor, the functional block of which is illustrated in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 to 4, an automatic icemaker according to an embodiment of the present invention will be discussed hereinafter. An ice-making tray 4 is rotatably attached to a control box 2. A reversible motor 6 is provided in the control box 2. A pinion gear 8 is mounted on an output shaft of the motor 6. A driven gear 10 is mounted on a shaft of the ice-making tray 4. The pinion gear 8 and the driven gear 10 are meshed with each other. The motor 6, the pinion gear 8 and the driven gear 10 constitute a rotating device for rotating the ice-making tray 4. A water supply port 12 is provided above the ice-making tray 4. A water supply solenoid valve 14 for opening and closing the water supply port 12 is provided at the water supply port 12. The ice-making tray 4 is provided with a plurality of small ice-making compartments 16 which are lined up along the direction of a rotation centerline of the ice-making tray 4. Groove-shaped water-passage channels 20 are formed in portions of partitions 18 between respective adjacent small ice-making compartments 16, which are offset from centers of the partitions 18, namely, in end portions of the partitions 18. An ice-fullness detecting arm 26 is rotatably provided at the control box 2 and adapted to be driven by the motor 6. Incidentally, a mechanism for transmitting the power of the motor 6 to the ice-fullness detecting arm 26 is not shown.
A microprocessor 28 containing an AD converter and a counter is provided in the control box 2. A temperature detecting sensor 22 is designed such that it successively outputs a temperature signal voltage corresponding to a temperature of the ice-making tray 4. A position detecting sensor 24 is designed such that it outputs a position signal voltage corresponding to a rotational position of the ice-making tray 4. An ice-fullness detecting sensor 30 is designed such that it outputs a signal voltage corresponding to amounts of ice cubes stored in an ice storage box (not shown), according to the movement of the ice-fullness detecting arm 26. A motor drive circuit 32 is designed such that it drives the motor 6. A valve drive circuit 34 is designed such that it drives the water supply solenoid valve 14. The microprocessor 28 is designed such that it gradually inputs the temperature signal voltage outputted from the temperature detecting sensor 22, and carries out an AD conversion, to thereby detect the temperature of the ice-making tray 4. Also, the microprocessor 28 is designed such that it detects from the signal voltage from the position detecting sensor 24 that the ice-making tray 4 is in a horizontal position with an opening portion of the ice-making tray 4 facing the water supply port 12. Moreover, the microprocessor 28 is designed such that it receives the signal voltage from the ice-fullness detecting sensor 30 and then detects that predetermined amounts of ice cubes have been stored in the ice storage box. Furthermore, the microprocessor 28 is designed such that it controls the motor drive circuit 32 and the valve drive circuit 34.
This automatic icemaker is fixed through a bracket (not shown) to a fixing part which is provided in advance in a freezing compartment of a refrigerator. In the automatic icemaker, water supplied to the ice-making tray 4 from the water supply port 12 is frozen by the cold in an interior of the freezing compartment, and the ice-making tray 4 is rotated by the motor 6, whereby formed ice cubes are released and discharged from the ice-making tray 4, and the discharged ice cubes are adapted to be dropped into the ice storage box. Moreover, a temperature detecting sensor (not shown) for detecting the temperature of the interior of the freezing compartment is provided and adapted to successively detect the temperature of the interior of the freezing compartment.
FIG. 5 is a functional block diagram of the microprocessor of the automatic icemaker shown in FIGS. 1 to 4. A water supply angle inclination instructing-means 38 controls the motor drive circuit 32 when a cycle of making ice is started, and then causes the ice-making tray 4 to be inclined at an angle equivalent to 20-30% of a water filling angle, namely, at the water supply angle. A valve opening instructing-means 40 controls the valve drive circuit 34 after the water supply angle inclination instructing-mean 38 causes the ice-making tray 4 to be inclined at the water supply angle, and then causes the water supply solenoid valve 14 to be opened. After a predetermined time has elapsed since the valve opening instructing-means 40 causes the water supply solenoid valve 14 to be opened, a valve closing instructing-means 42 controls the valve drive circuit 34 and then causes the water supply solenoid valve 14 to be closed. A water filling angle inclination instructing-means 44 controls the motor drive circuit 32 after the valve closing instructing-means 42 causes the water supply solenoid valve 14 to be closed, and then causes the ice-making tray 4 to be inclined at the water filling angle. After a predetermined time has elapsed since the water filling angle inclination instructing-means 44 causes the ice-making tray 4 to be inclined at the water filling angle, a horizontal position return instructing-means 46 controls the motor drive circuit 32 and then cause the ice-making tray 4 to be returned to the horizontal position.
Referring now to FIGS. 6 and 7, the operation of the automatic icemaker shown in FIGS. 1 to 4 will be discussed hereinafter. First of all, when ice-making is to be started, the microprocessor 28 confirms from the output of the position detecting sensor 24 that the ice-making tray 4 is in the horizontal position in a condition where the opening portion of the ice-making tray 4 faces the water supply port 12. At this time, unless the ice-making tray 4 is in the horizontal position, the microprocessor 28 controls the motor drive circuit 32 to drive the motor 6, whereby the ice-making tray 4 is rotated to the horizontal position. Then, when the ice-making cycle is started, the microprocessor 28 (the water supply angle inclination instructing-means 38) causes the ice-making tray 4 to be inclined at the water supply angle (S1) as shown in FIG. 7A. Then, the microprocessor 28 (the valve opening instructing-means 40) causes the water supply solenoid valve 14 to be opened (S2). Thereupon, water is supplied to the ice-making tray 4 from the water supply port 12. After a predetermined time has elapsed since the water supply solenoid valve 14 is opened, the microprocessor 28 (the valve closing instructing-means 42) causes the water supply solenoid valve 14 to be closed (S3 and S4). That is, the quantity of the water supplied to the ice-making tray 4 is managed depending on time expended during the water supply solenoid valve 14 is opened. The time which is expended during the water supply solenoid valve 14 is opened is set to time during which the surface of the water 36 supplied to the ice-making tray 4 which is in the horizontal condition does not reach bottom surfaces of the water passage channels 20. Subsequently, the microprocessor 28 (the water filling angle inclination instructing-means 44) causes the ice-making tray 4 to be inclined at the water filling angle (S5) as shown in FIG. 7B. Then, the water 36 stored in the ice-making tray 4 passes through the water passage channels 20 and is then spread evenly into the respective small ice-making compartments 16. Subsequently, after a predetermined time has elapsed since the ice-making tray 4 is inclined at the water filling angle, the microprocessor 28 (the horizontal position return instructing-means 46) causes the ice-making tray 4 to be returned to the horizontal position (S6 and S7) as shown in FIG. 7C.
Subsequently, when the microprocessor 28 detects from the output of the position detecting sensor 24 that the ice-making tray 4 is in the horizontal position, the microprocessor 28 detects the temperature of the ice-making tray 4 from the output of the temperature detecting sensor 22, and stands by until a predetermined time elapses in a condition where the temperature of the ice-making tray 4 becomes a temperature less than a preset temperature. Then, the water supplied to the respective small ice-making compartments 16 is cooled by the cold in the freezing compartment of the refrigerator and then frozen. Subsequently, when the microprocessor 28 detects that a predetermined time has elapsed in the condition where the temperature of the ice-making tray 4 is lower than the preset temperature, the microprocessor 28 controls the motor drive circuit 32 to drive the motor 6, whereby the ice-making tray 4 is rotated, and formed ice cubes are released from the ice-making tray 4 by twisting of the ice-making tray 4, or the like and dropped into the ice storage box. After the respective small ice-making compartments 16 are positively emptied, the ice-making tray 4 is returned to the horizontal position.
In this way, the water supply, ice-making and discharge of the ice cubes are repeatedly carried out according to the predetermined sequence, thus automatically making ice cubes.
When this ice-making cycle is successively carried out, the ice storage box is filled with the discharged ice cubes. When the ice-fullness detecting sensor 30 detects that the amount of the ice cubes stored in the ice storage box exceeds a predetermined amount and the microprocessor 28 detects the signal from the ice-fullness detecting sensor 30, the microprocessor 28 causes the ice-making cycle to be temporarily stopped. When the microprocessor 28 detects that the amount of the ice cubes in the ice storage box becomes less than the predetermined amount by removal of the ice cubes from the ice storage box by a user, the microprocessor 28 causes the ice-making cycle to be resumed. During the above series of the ice-making cycle, the microprocessor 28 monitors the temperature detected by the temperature detecting sensor 22. When any operation such as opening of a door of the refrigerator is carried out during the operation of the automatic icemaker, whereby the temperature becomes different from an original value of the temperature, the microprocessor 28 judges the situation as an abnormality, and then carries out abnormal-situation processing which is predetermined per each stage.
In the automatic icemaker constructed as discussed above, when the supply of the water to the ice-making tray 4 is to be started, the ice-making tray 4 is adapted to be inclined at the water supply angle, so that even if the flow of the water is strong, the water can be supplied to the ice-making tray 4 without spilling out of the ice-making tray 4. Moreover, after the supply of the water to the ice-making tray 4 is completed, the ice-making tray 4 is inclined at the water filling angle, so that the water 36 can be spread evenly into the respective small ice-making compartments 16. In addition, in the condition where the ice-making tray 4 is made to become horizontal, the surface of the water 36 supplied to the small ice-making compartments 16 does not reach the bottom surfaces of the water passage channels 20, so that the waters in the respective small ice-making compartments 16 can be made to be independent from one another and, therefore, when the ice cubes are to be discharged from the ice-making tray 4, adjacent ice cubes are not freezingly connected to each other via ice formed in the water passage channels 20. Therefore, it is possible to positively cause respective ice cubes to be independent from one another, thus improving users' convenience. Moreover, the rotation of the ice-making tray 4 allows the independence of the ice cubes from one another to be realized, so that torque to be required in order to twist the ice-making tray 4 at the time of the discharge of the ice cubes can be reduced. It is unnecessary to provide a heater or the like, so that the number of parts is not increased, the ice-making tray 4 is not large-sized, and ice cubes which are uniform in size can be made.
FIG. 8 is a functional block diagram of a microprocessor of an automatic icemaker according to another embodiment of the present invention. When the ice-making cycle is started, an operation start instructing-means 52 controls the motor drive circuit 32, cause the ice-making tray 4 to be successively rotated by the motor 6 in such a direction that the water passage channels 20 face downward and, at the same time, controls the valve drive circuit 34 to cause the water supply solenoid valve 14 to be opened. After a predetermined time has elapsed since the water supply solenoid valve 14 is opened by the operation start instructing-means 52, a valve closing instructing-means 54 controls the valve drive circuit 34 and then cause the water supply solenoid valve 14 to be closed. When a tilt angle of the ice-making tray 4 reaches the water filling angle, a water filling angle inclination instructing-means 56 controls the motor drive circuit 32 and then cause the ice-making tray 4 to be kept at the water filling angle. After a predetermined time has elapsed since the water supply solenoid valve 14 is closed by the valve closing instructing-means 54 and the tilt angle of the ice-making tray 4 is kept at the water filling angle by the water filling angle inclination instructing-means 56, a horizontal position return instructing-means 58 controls the motor drive circuit 32 and then cause the ice-making tray 4 to be returned to the horizontal position.
Referring now to FIG. 9, the operation of the automatic icemaker having the microprocessor, the functional block of which is shown in FIG. 8, will be discussed hereinafter. First of all, when the ice making cycle is started, the microprocessor 28 (the operation start instructing-means 52) causes the ice-making tray 4 to be successively rotated in such a direction that the water passage channels 20 face downward and, at the same time, causes the water supply solenoid valve 14 to be opened (S1). Thereupon, the tilt angle of the ice-making tray 4 successively becomes large and, at the same time, water is supplied to the ice-making tray 4. That is, the supply of the water to the ice-making tray 4 is carried out while causing the ice-making tray 4 to be rotated in such a direction that the water passage channels 20 face downward, according to the quantity of the water stored in the small ice-making compartments 16 by the supply of the water. Then, after a predetermined time has elapsed since the water supply solenoid valve 14 is opened, the microprocessor 28 (the valve closing instructing-means 54) causes the water supply solenoid valve 14 to be closed and the microprocessor 28 (the water filling angle inclination instructing-means 56) causes the ice-making tray 4 to be kept at the water filling angle when the tilt angle of the ice-making tray 4 reaches the water filling angle (S2 to S6). Thereupon, the water 36 stored in the ice-making tray 4 passes through the water passage channels 20 and is then spread evenly into the respective small ice-making compartments 16. Then, after a predetermined time has elapsed since the water supply solenoid valve 14 is closed and the tilt angle of the ice-making tray 4 is kept at the water filling angle, the microprocessor 28 (the horizontal position return instructing-means 58) causes the ice-making tray 4 to be returned to the horizontal position (S7 and S8).
In the automatic icemaker constructed as discussed above, the supply of the water is carried out while causing the ice-making tray 4 to be rotated according to the quantity of the water stored in the small ice-making compartments by the supply of the water, so that even if the flow of the water is strong, it is possible to supply the water to the ice-making tray 4, without allowing the water to spill out of the ice-making tray 4. Moreover, the ice-making tray 4 is kept in the condition where it is inclined at the water filling angle after the supply of the water to the ice-making tray 4 is completed, so that the water can be spread evenly into the respective small ice-making compartments 16. In addition, in the same manner as in the automatic icemaker shown in FIGS. 1 to 4, adjacent ice cubes are not freezingly connected to each other via the ice formed in the water passage channels 20, when the ice cubes are to be discharged from the ice-making tray 4.
Incidentally, while the embodiments of the present invention have been described in connection with the automatic icemaker having the single ice-making tray, the present invention may be applied to an automatic icemaker having two ice-making trays combined together back-to-back, namely, two ice-making trays combined together with bottom surfaces of small ice-making compartments 16 being opposed to each other. Moreover, while the water supply angle is set to a value equivalent to 20-30% of the water filling angle in the above-mentioned embodiments, a value of the water supply angle which is less than a value of the water filling angle is sufficient. In addition, while the temperature detecting sensor 22 which is designed such that it outputs the temperature signal voltage corresponding to the temperature of the ice-making tray 4 is employed in the above-mentioned embodiments, a temperature detecting sensor which is designed such that it outputs a temperature signal voltage corresponding to the temperature of the water poured into the respective small ice-making compartments 16 of the ice-making tray 4 (or the temperature of ice), may be employed. Moreover, while in the above-mentioned embodiments, the supplied water is made to be evenly spread into the respective small ice-making compartments 16 by causing the ice-making tray 4 to be returned to the horizontal position after the predetermined time has elapsed since the ice-making tray 4 is inclined at the water filling angle, or by causing the ice-making tray 4 to be returned to the horizontal position after the predetermined time has elapsed since the water supply solenoid valve 14 is closed and the tilt angle of the ice-making tray 4 is kept at the water filling angle, the even spreading of the water into the respective small ice-making compartments 16 may be confirmed by variation in the temperature signal voltage which is detected by the temperature detecting sensor 22 provided at the ice-making tray 4. Moreover, while the microprocessor 28 having the AD converter and the counter contained therein is employed in the above-mentioned embodiments, a microprocessor having a counter contained therein and an AD converter may be employed. In addition, while in the above-mentioned embodiments, the supply of the water to the ice-making tray 4 is carried out while causing the ice-making tray 4 to be successively rotated, the supply of the water to the ice-making tray 4 may be carried out while causing the ice-making tray 4 to be rotated step by step.
The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

Claims

1. An automatic icemaker capable of being installed in a freezing compartment and automatically making and discharging ice cubes, said automatic icemaker comprising:

at least one ice-making tray having a plurality of small ice-making compartments, partitions disposed between respective adjacent small ice-making compartments, and groove-shaped water-passage channels formed in portions of said partitions which are offset from centers of said partitions; and

a rotating device for rotating said ice-making tray;

wherein water is supplied after said ice-making tray is inclined at a water supply angle less than a water filling angle in such a direction that said water passage channels face downward.

2. An automatic icemaker according to claim 1, further including a microprocessor, said microprocessor comprising a water supply angle inclination instructing-means for causing said ice-making tray to be inclined at the water supply angle when an ice-making cycle is started, a valve opening instructing-means for causing a water supply solenoid valve to be opened after said water supply angle inclination instructing-means causes said ice-making tray to be inclined at the water supply angle, a valve closing instructing-means for causing said water supply solenoid valve to be closed after the water supplied to said ice-making tray is spread evenly into said small ice-making compartments, a water filling angle inclination instructing-means for causing said ice-making tray to be inclined at the water filling angle after said valve closing instructing-means causes said water supply solenoid valve to be closed, and a horizontal position return instructing-means for causing said ice-making tray to be returned to a horizontal position after a predetermined time has elapsed since said water filling angle inclination instructing-means causes said ice-making tray to be inclined at the water filling angle.

3. An automatic icemaker according to claim 2, wherein said microprocessor has an AD converter contained therein.

4. An automatic icemaker according to claim 1, further including a temperature detecting sensor for detecting a temperature of said ice-making tray or a temperature of ice, and a temperature detecting sensor for detecting a temperature of an interior of said freezing compartment.

5. An automatic icemaker according to claim 1, wherein two said ice-making trays are combined together back-to-back.

6. An automatic icemaker capable of being installed in a freezing compartment and automatically making and discharging ice cubes, said automatic icemaker comprising:

a rotating device for rotating the ice-making tray;

wherein water is supplied while said ice-making tray is rotated in such a direction that the water-passage channels face downward, according to a quantity of the water stored in the small ice-making compartments by the supply of the water.

7. An automatic icemaker according to claim 6, wherein the water is supplied while said ice-making tray is successively rotated.

8. An automatic icemaker according to claim 7, further including a microprocessor, said microprocessor comprising an operation start instructing-means for causing said ice-making tray to be rotated in such a direction that said water passage channels face downward and for causing a water supply solenoid valve to be opened, when an ice making cycle is started, a valve closing instructing-means for causing said water supply solenoid valve to be closed after a predetermined time has elapsed since said operating start instructing-means causes said water supply solenoid valve to be opened, a water filling angle inclination instructing-means for causing said ice-making tray to be kept at the water filling angle when a tilt angle of said ice-making tray reaches the water filling angle, and a horizontal position return instructing-means for causing said ice-making tray to be returned to a horizontal position after a predetermined time has elapsed since said valve closing instructing-means causes said water supply solenoid valve to be closed and said water filling angle inclination instructing-means causes the tilt angle of said ice-making tray to be kept at the water filling angle.

9. An automatic icemaker according to claim 8, wherein said microprocessor has an AD converter contained therein.

10. An automatic icemaker according to claim 6, wherein the water is supplied while said ice-making tray is rotated step by step.

11. An automatic icemaker according to claim 6, further including a temperature detecting sensor for detecting a temperature of said ice-making tray or a temperature of ice, and a temperature detecting sensor for detecting a temperature of an interior of said freezing compartment.

12. An automatic icemaker according to claim 6, wherein two said ice-making trays are combined together back-to-back.