Patent Publication Number: US-8539779-B2

Title: Ice maker, refrigerator having the same, and ice making method thereof

Description:
RELATED APPLICATION 
     The present disclosure relates to subject matter contained in priority Korean Application No. 10-2009-0055656, filed on Jun. 22, 2009, which is herein expressly incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ice maker, a refrigerator including the ice maker, and an ice making method, and particularly, to an ice maker that occupies a small space and provides an enhanced degree of spatial utilization and placement options within a refrigerator. 
     2. Background of the Invention 
     A home refrigerator serves to store food items in an accommodation space at a low temperature. The refrigerator is divided into a freezing chamber for storing food items at a temperature below zero degrees Celsius, and a refrigerating chamber for storing food items at a temperature above zero degrees Celsius. As demands for ice increases, a large number of refrigerators having automatic ice makers for making ice are being presented. 
     The ice maker may be installed at either the freezing chamber or the refrigerating chamber, depending on the type of refrigerator. In the case of installing the ice maker at the refrigerating chamber, cool air inside the freezing chamber is guided to the ice maker to perform an ice making operation. 
     Methods for separating ice from the ice maker may include a torsion method, an ejection method, and a rotation method. The torsion method is a method for separating ice by twisting the ice maker, the ejection method is a method for separating ice from the ice maker by an ejector installed above the ice maker, and the rotation method is a method for separating ice by rotating the ice maker. 
     However, the conventional ice makers and refrigerators provided with the conventional ice makers have several drawbacks. 
     Firstly, the conventional ice maker makes ice by containing water in a horizontal ice container. Here, the ice container occupies a large space, and an ice separation unit for separating ice from the ice maker occupies a large space. This may reduce the entire utilization space inside the refrigerator. Furthermore, in the case of reducing the size of the ice maker, the amount of ice that can be made at one time is reduced. This may cause ice not to be rapidly provided in summer when a large amount of ice is required. 
     Secondly, the conventional ice maker has a structure to drop formed ice downwardly to a location below the ice maker. Accordingly, in the case of a refrigerator having a dispenser, an ice making chamber has to be installed at a position higher than the dispenser. However, in the case of a 3-door bottom freezer type refrigerator where a freezing chamber is installed at a lower side and a refrigerating chamber including an ice making chamber is installed at an upper side, when the ice making chamber is installed at a high position, the freezing chamber is spaced far from the ice making chamber, and cooling air loss may occur when cool air from the freezing chamber is transferred to the ice making chamber. This may reduce the energy efficiency of the refrigerator. 
     Thirdly, the conventional ice maker has an ice making unit and an ice separating unit operated by individual mechanisms. This may cause the entire configuration and control to be complicated, resulting in an increase in the fabrication costs of the ice maker. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an ice maker having a slim configuration which occupies a small space within a refrigerator. 
     Another object of the present invention is to provide an ice maker locatable within a refrigerator at a location that permits a reduction of air loss occurring when cool air in a freezing chamber is supplied to an ice making chamber, by shortening a distance between the freezing chamber and the ice making chamber by lowering an installation height of the ice maker. 
     Still another object of the present invention is to provide an ice maker capable of reducing fabrication costs and reducing malfunctions thereof by having a simplified configuration and precise controls. 
     Still other objects of the present invention are to provide a refrigerator having the ice maker, and an ice making method thereof. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an ice maker, comprising: a tray having an ice making space; a piston for separating ice from the tray by pushing up the ice in a slidably coupled state to the tray; and a driving unit coupled to the piston, for up-down moving the piston. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is also provided a refrigerator, comprising: a refrigerator body; a freezing chamber formed at the refrigerator body; a refrigerating chamber formed at the refrigerator body, and partitioned from the freezing chamber; an ice making chamber installed at the refrigerating chamber of the refrigerator body, for making ice by receiving cool air inside the freezing chamber; and an ice maker installed inside the ice making chamber, for making ice, wherein the ice maker separates ice from a tray by using an up-down motion of a piston. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is still also provided an ice making method of a refrigerator, comprising: a water supplying step for supplying water to a tray; an ice making step for cooling the water contained in the tray, and thereby making ice; and an ice separating step for upwardly moving the ice inside the tray by a piston, cutting the ice, and transferring the cut ice to a preset position. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a perspective view of a bottom freezer type refrigerator having an ice maker according to the present invention; 
         FIGS. 2 and 3  are perspective views showing an operation state of the ice maker of  FIG. 1  according to an up or down position of a piston; 
         FIG. 4  is a sectional view taken along line ‘IV-IV’ in  FIG. 2 ; 
         FIG. 5  is an exploded perspective view showing a configuration of the piston of  FIGS. 2 and 3 ; 
         FIG. 6  is a schematic view showing a configuration of a control unit of  FIG. 4 ; 
         FIGS. 7(   a )- 7 ( d ) are longitudinal sectional views of the ice maker of  FIGS. 2 and 3  showing an ice making process; 
         FIG. 8  is a flowchart showing an ice making process by the ice maker of  FIGS. 2 and 3 ; 
         FIG. 9  is a schematic view showing the ice maker of  FIG. 1  according to another embodiment of the present invention; and 
         FIGS. 10 and 11  are a rear view and a side sectional view each showing an arrangement structure of the ice maker of  FIGS. 2 and 3  and a dispenser according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description will now be given in detail of the present invention, with reference to the accompanying drawings. 
     Hereinafter, an ice maker, a refrigerator having the same, and an ice making method thereof according to the present invention will be explained in more detail with reference to the attached drawings. 
     Referring now to  FIG. 1 , the refrigerator according to the present invention comprises a freezing chamber  2  installed at a lower side of a refrigerator body  1  and configured to store food items at a temperature below zero degrees Celsius, and a refrigerating chamber  3  installed at an upper side of the refrigerator body  1  and configured to store food items at a temperature above zero degrees Celsius. A freezing chamber door  4  is slidably installed at the freezing chamber  2  so as to open and close the freezing chamber  2  in a drawer-like manner. A plurality of refrigerating chamber doors  5  are rotatably installed at both sides of the refrigerating chamber  3  so as to open and close the refrigerating chamber  3 . A mechanical chamber is located at a lower end of a rear portion of the refrigerator body  1  where a compressor and a condenser are installed. 
     An evaporator for supplying cool air to the freezing chamber  2  or the refrigerating chamber  3  by being connected to the compressor and the condenser is installed at a rear portion of the refrigerator body  1 , between an outer case and an inner case at a rear wall of the freezing chamber. However, the evaporator may be installed at a side wall or an upper wall or the refrigerator body. Alternatively, the evaporator may be installed at a barrier wall partitioning the freezing chamber  2  and the refrigerating chamber  3  from each other. One single evaporator may be installed only at the freezing chamber  2  to supply cool air to the freezing chamber  2  and the refrigerating chamber  3  in a distribution manner. Alternatively, a freezing chamber evaporator and a separate refrigerating chamber evaporator may be installed respectively, so as to independently supply cool air to the freezing chamber  2  and the refrigerating chamber  3 . 
     An ice making chamber  51  for making ice and storing the ice is formed at an upper inner wall surface of the refrigerating chamber door  5 . An ice maker  100  for making ice is installed inside of the ice making chamber  51 . A dispenser  52  is located below the ice making chamber  51 , so as to be outwardly exposed on a front side of the refrigerator chamber door  5 , so that ice made by the ice maker  100  can be drawn out of the refrigerator. 
     The operation of the refrigerator will be explained as follows. 
     Once a load is detected from the freezing chamber  2  or the refrigerating chamber  3 , the compressor is operated to generate cool air by the evaporator. A portion of the cool air is supplied to the freezing chamber  2  and the refrigerating chamber  3  in a distribution manner, whereas another portion of the cool air is supplied to the ice making chamber  51 . The cool air supplied to the ice making chamber  51  is heat-exchanged so that ice can be formed by the ice maker  100  mounted at the ice making chamber  51 , and then is returned into the freezing chamber  2  or is supplied to the refrigerating chamber  3 . The ice made by the ice maker  100  is drawn out through the dispenser  52 . These processes are repeatedly performed. 
     As shown in  FIGS. 2 and 3 , the ice maker  100  includes a water supply unit  110  connected to a water supply source for supplying water, a tray  120  for performing an ice making operation by receiving the water supplied from the water supply unit  110 , an ice separation unit  130  for separating ice made in the tray  120  from the tray  120  in a push-up manner, and a transfer unit for transferring the ice (I) separated from the tray  120  to the dispenser  52  after cutting the ice (I) into a proper size. 
     As shown in  FIGS. 2 to 4 , the water supply unit  110  includes a water supply pipe  111  for connecting the water supply source to the tray  120 , a water supply valve  112  installed at an intermediate part of the water supply pipe  111  for controlling a water supply amount. A water supply pump  113  may be provided at an upstream side or a downstream side of the water supply valve  112  for pumping water. The water supply pump  113  serves to supply a uniform water pressure and flow. However, the water supply pump  113  is not necessarily required. For example, where the water supply pump  113  is not provided, water supply may be performed by using a height difference between the water supply source and the tray  120 , or by water pressure of the source. 
     The water supply pipe  111  may be independently connected to ice making tubes  122  of the tray  120  to be later explained. However, as shown in the drawings, the water supply pipe  111  is connected to one ice making tube  122 , especially, the intermediate ice making tube  122 , and the other ice making tubes are in fluid communication with the intermediate ice making tube to permit water flow among the ice making tubes  122 , which is preferable in terms of controls and fabrication costs. 
     The water supply pipe  111  may be directly connected to the water supply source for supplying water. In addition, the water supply pipe  111  may be connected to a water tank provided in the refrigerating chamber  3  and storing a predetermined amount of water therein. In this case, the water tank serves as the water supply source. In order to supply a predetermined amount of water to each of the ice making tubes  122  of the tray  120 , a water level sensor may be installed at the tray  120 , a flow amount sensor for sensing a flow amount of water may be installed at the water supply pipe, or a water level sensor may be installed at the water tank. 
     The water supply valve  112  and the water supply pump  113  may be electrically connected to a control unit  150  so as to exchange signals with each other. The control unit  150  may control a water supply amount based on a real time value sensed by the water level sensor or the flow amount sensor. Alternatively, the control unit  150  may periodically turn on/off the water supply valve  112  and the water supply pump  113  by setting an operation time of the water supply valve  112  and the water supply pump  113  according to predefined data. 
     A single tray  120  may be provided according to an ice making capacity of the refrigerator. However, a plurality of trays  120  may be provided for increasing an ice making capacity of the refrigerator. When a plurality of trays  120  are provided, the plurality of trays  120  may be arranged in one line, or may be arranged in plurality of lines, taking into consideration the relationships with the peripheral components. In order to minimize each width of the trays  120  in back and forth directions, the trays  120  are preferably arranged on the same plane in one line. However, in order to minimize each width of the trays  120  in right and left directions, the trays  120  are preferably arranged in a plurality of lines. The arrangement of the trays  120  may be suitably controlled according to particular needs. 
     As shown in  FIGS. 2 and 3 , the tray  120  includes a housing  121  formed to have a long length in a horizontal direction, and a plurality of ice making tubes  122  disposed below the housing  121  so as to be in parallel in a horizontal direction, and having ice making spaces (S) communicated with a lower portion of the housing  121 . 
     The housing  121  and the ice making tubes  122  may be integrally formed with each other. Alternatively, the ice making tubes  122  may be respectively assembled to the housing  121  by welding or other fastening methods. For instance, in the case of integrally forming the housing  121  and the ice making tubes  122  with each other, the ice making tubes  122  may be formed in a cylindrical shape so that upper and lower ends thereof are open. This is preferable for facilitation of the assembly of pistons  131  to be explained later. However, in the case of assembling the ice making tubes  122  to the housing  121 , the ice making tubes  122  may be formed so that the upper ends thereof are open, while the lower ends thereof are closed. In this case, through holes may be formed at the center of the closed lower ends of the ice making tubes  122  for permitting rod portions  133  of the pistons  131  to slidably penetrate therethrough. 
     As shown in  FIGS. 2 to 4 , the water supply pipe  111  for supplying water may be connected to one of the ice making tubes  122 , for example, the intermediate ice making tube  122 . In addition, a water flow path  123  may be formed so that water can be transferred to both ice making tubes  122  adjacent to the intermediate ice making tube  122 . The water flow path  123  may be implemented as holes, or grooves formed at upper ends of the openings of the ice making tubes  122 . 
     The ice separation unit  130  includes a plurality of pistons  131  for linearly moving ice upwardly within the ice making tubes  122 , and a driving unit  136  for moving the pistons  131  upwardly and downwardly. 
     As shown in  FIGS. 2 ,  3  and  5 , the pistons  131  include head portions  132  slidably coupled to inner circumferential surfaces of the ice making tubes  122 , to thereby form ice making spaces (S), for pushing up the ice, and rod portions  133  integrally formed at bottom surfaces of the head portions  132  or assembled thereto, for receiving a driving force of the driving unit  136 . 
     The head portions  132  may be formed in a disc shape having nearly the same size as an inner diameter of the ice making tubes  122 . Gaskets  134  having a ring shape may be coupled to outer circumferential surfaces of the head portions  132  for prevention of leakage of water filled in the ice making spaces (S). Alternatively, the head portions  132  may have an oval shape, or a rectangular or square shape, for slidably coupling with a correspondingly shaped oval, rectangular or square ice making tube  122 . 
     The rod portion  133  may be formed to have a predetermined length in a vertical direction. Screw threads  133   a  are formed on outer circumferential surfaces of the rod portions  133 , and are engaged with inner portions of driven gears  138 , so that the rod portions  133  are moved up or down when the driven gears  138  rotate. Stoppers  135  for limiting an up-motion height of the pistons  131  may be formed at lower ends of the rod portions  133 . The stoppers  135  may be formed in a sleeve shape to be assembled to the rod portions  133 . 
     The driving unit  136  includes a driving gear  137  installed in a horizontal direction and rotated in the horizontal direction (first axial direction), and driven gears  138  engaged with the driving gear  137  and the pistons  131 , for moving the pistons  131  up and down while the driven gears  138  are rotated in a longitudinal direction (second axial direction perpendicular to the first axial direction) by the driving gear  137 . 
     The driving gear  137  is implemented as bar-shaped worm gear having a length longer than a horizontal length of the tray  120 , and the driven gears  138  are implemented as ring-shaped worm wheels. The driven gears  138  have outer gears  138   a  on outer circumferential surfaces thereof so as to be engaged with the driving gear  137 . The driven gears  138  additionally have inner gears  138   b  on inner circumferential surfaces thereof so as to be engaged with the screw threads  133   a  of the rod portions  133  attached to the pistons  131 . 
     The driving gear  137  and the driven gears  138  may be coupled to a rotation shaft of a driving motor for rotating a cutter by using one or a plurality of intermediate gears. However, the driving gear  137  and the driven gears  138  may be coupled to the rotation shaft of the driving motor by a driving force transmitting member such as a belt, chain, or other flexible force transferring member. 
     The driven gears  138  may be rotatably coupled to worm wheel bases  139 , and the worm wheel bases  139  may be fixedly installed to an inner wall surface of the ice making chamber  51 . 
     The ice inside the ice making tubes  122  may be separated from the ice making tubes  122  by an upward motion of the pistons  131 , i.e., by a pushing force of the pistons  131  generated by a driving motor  143 , without applying heat to the ice making tubes  122 . Alternatively, the ice may be separated from the ice making tubes  122  by applying a predetermined amount of heat to the ice making tubes  122  by a heater installed on an outer peripheral surface of the tray  120 , before the ice is pushed up by the pistons  131 . 
     The heater may be implemented as a hot wire heater wound on an outer peripheral surface of the tray  120 . In this case, the heater may be formed as a single circuit or a plurality of circuits according to the shape of the tray  120 . 
     The heater may be controlled so as to be communicated with the water supply unit  110 . For instance, a microcomputer may determine whether water is being supplied to the tray  120  for ice making, whether an ice making operation is being performed, or whether the ice made in the tray  120  is being separated from the tray  120 , according to changes of values sensed by the water level sensor or the flow amount sensor of the water supply unit  110 . If it is determined that water is being supplied to the tray  120  for ice making, or if it is determined that an ice making operation is being performed, the operation of the heater is stopped. However, if it is determined that the ice made in the tray  120  is being separated from the tray  120 , the operation of the heater is started. 
     The time to operate the heater may be determined by real-time or periodically sensing the temperature of the tray  120 . Alternatively, the heater  131  may be forcibly operated based on a data value set to indicate a lapsed time after changes of values sensed by the water level sensor or the flow amount sensor of the water supply unit  110 . That is, whether the ice making operation has been completed or not may be checked by sensing the temperature of the tray  120 , or through an ice making time. For instance, when the temperature of the tray  120  measured by a temperature sensor mounted at the tray  120  is less than a predetermined temperature (e.g., about −9 degrees Celsius), it is determined that the ice making operation has been completed. Alternatively, when a predetermined time lapses after a water supply operation, it is determined that the ice making operation has been completed. 
     Although not shown, the heater may be also implemented as a conductive polymer, a plate heater with a positive thermal coefficient, an AL thin film, or a heat transfer material, rather than the aforementioned hot wire heater. 
     Rather than being attached onto the outer peripheral surface of the tray  120 , the heater may instead be installed inside the tray  120 , or may be provided on an inner surface of the tray  120 . Alternatively, the tray  120  may be implemented as a heating resistor which emits heat when electricity is applied to one or more parts thereof. This may allow the tray  120  to serve as the heater without installing an additional heater. 
     The heater may operate as a heat source by being installed at a position spaced from the tray  120  by a predetermined interval, without coming in contact with the tray  120 . As another example, the heat source may be implemented as an optical source for irradiating light to at least one of the ice and the tray  120 , or a magnetron for irradiating microwaves to at least one of the ice and the tray  120 . The heat source such as the heater, the optical source, and the magnetron melts a part of an interface between the ice and the tray  120 , by applying thermal energy to at least one of the ice and the tray  120 , or the interface therebetween. Accordingly, once the pistons  131  are operated, the ice is separated from the tray  120  by the pistons  131  even in a condition where the interface between the ice and the tray  120  has not melted completely. 
     The transfer unit  140  includes a cutter  141  rotatably installed at an inner space of the housing  121  and configured to cut the ice (I), a chute tube  142  for guiding the ice cubes cut by the cutter  141  to the dispenser, and a driving motor  143  for rotating the cutter  141 . 
     As shown in  FIGS. 2 and 4 , the cutter  141  includes a plurality of cutter plates  145  rotatably disposed and spaced apart from each other by a predetermined distance, and one or more blades  146  formed in a spiral shape with both ends thereof coupled to surfaces of the two cutter plates  145 . 
     One of the cutter plates  145  adjacent to the driving motor  143  is coupled to a rotation shaft of the driving motor  143 , whereas the other of the cutter plates  145  is rotatably coupled to the chute tube  142 . 
     Since the ice (I) made in the ice making tubes  122  and pushed up is a contiguous (non-cut) ice mass having a cylindrical shape, the cutter  146  may be formed in a wound shape by about 180° so as to smoothly cut the ice (I). 
     Since the two cutter plates  145  are connected to each other only by the blade  146  without using an additional bar, the ice may be smoothly upwardly moved from the tray  120  without being blocked by the cutter  141 . 
     The cutter  141  may be formed in other ways to cut the ice mass into separated ice pieces having a proper size. In case of forming the blade  146  of the cutter  141  in a screw shape, the blade  146  can move the ice (I) in a consecutive push manner. This may allow a free configuration of an arrangement shape of the tray  120  or a direction to draw out the ice. Furthermore, in case of forming the blade  146  of the cutter  141  in a screw shape, the number of the chute tubes  143  and the position of the ice drawing opening  147  may be varied. More specifically, when the screw of the blade  146  is implemented in one direction as shown in  FIG. 4 , the ice drawing opening  147  is formed at one end of the blade  146 . However, when the screw of the blade  146  is implemented in two directions, the ice drawing opening  147  may be formed at both ends of the blade  146 , or at an intermediate part of the blade  146 . 
     The chute tube  142  may be formed in a cylindrical shape or a quadrangular shape having nearly the same diameter as the housing  121 . The end of the chute tube  142  may be directly connected to the dispenser, or to an ice storage container. 
     The driving motor  143  may be controlled by a control unit  150 , for example a microcomputer, electrically connected to the driving motor  143 . For instance, as shown in  FIG. 6 , the control unit  150  includes a sensing unit  151  for sensing the temperature of the tray  120  or sensing a lapsed time after water supply, a determination unit  152  for determining whether the ice making operation has been completed or not by comparing the temperature or time sensed by the sensing unit  151  with a reference value, and a command unit  153  for controlling whether to operate the driving motor  138  based on the determination by the determination unit  152 . If a heater is provided, the control unit  150  may also control the operation of the heater. 
     Referring now to  FIGS. 7 and 8 , once ice making is requested, the ice maker  100  is turned on, and an ice making operation starts ( 51 ). Once the ice making operation starts, the water supply unit  110  supplies water to the ice making tubes  122  of the tray  120  (S 2 ). Here, a water supply amount is real-time sensed by a water level sensor installed at the tray  120 , or a flow amount sensor installed at a water supply pipe, or a water level sensor installed at a water tank, etc. Then, the sensed water supply amount is transmitted to the microcomputer  150 . And, the microcomputer  150  compares the received water supply amount with a preset water supply amount (S 3 ). Based on the comparison, it is determined whether a preset amount of water has been supplied to the ice making tubes  122  of the tray  120 . If it is determined that a preset amount of water has been supplied to the ice making tubes  122  of the tray  120 , a water supply valve of the water supply unit  110  is blocked to stop a supply of water to the ice making tubes  122  of the tray  120 . 
     Once the water supply to the ice making tubes  122  of the tray  120  has been completed, the water inside the tray  120  is exposed to cool air supplied to the ice making chamber  51  for a predetermined time, to be frozen (S 5 ). While the water inside the tray  120  is being frozen, a temperature sensor periodically or real-time senses the temperature of the tray  120  to transmit the sensed temperature to the microcomputer  150 . Then, the microcomputer  150  compares the sensed temperature with a preset temperature (S 6 ). Based on this comparison, it is determined whether the surface of the water inside the tray  120  has been frozen. If it is determined that the water inside the tray  120  has been frozen, all the processes are stopped to convert the current operation into the ice separating operation (S 7 ˜S 8 ). 
     Once ice separation is requested, the driving motor  143  is operated by the control unit  150 . As the driving motor  143  is operated, the driving gear  137  (worm gear) is rotated. Then, the driving gear  137  rotates the driven gears  138  (worm wheels), and thus the driven gears  138 , which are coupled to the screw threads  133   a , move the pistons  131  upwardly (S 9 ). Then, the head portions  132  of the pistons  131  push up the ice. As the ice is upwardly moved toward the cutter  141 , the ice separating operation is performed (S 10 ). 
     In an arrangement where a heater is used, the heater and the driving motor  143  are operated by the control unit  150 . Once the heater is operated, heat is supplied to the tray  120 , thereby melting an outer surface of the ice contacting an inner surface of the tray  120 . Accordingly, the ice is easily separated from the tray  120 . 
     Next, while the driving gear  137  is rotated by the driving motor  143 , the cutter  141  also starts to be rotated (S 11 ). Accordingly, the ice inside the tray  120  is pushed up to be cut into a predetermined size. Then, the cut ice cubes are transferred to the chute tube  142  by the blade  146 , and subsequently discharged toward the dispenser, or toward an ice storage container (S 12 ). 
     While the ice is being separated from the tray  120  or while the ice separating operation is prepared, supply of cool air to the ice making chamber  51  is preferably stopped in order to facilitate the ice separating operation, and in order to reduce power supplied to the heater in the case of implementing the heater. 
     Once the ice discharging operation is completed, the operation of the cutter  141  is stopped. And, the driving motor  143  is operated in a reverse direction to restore the pistons  131  to the original positions (S 13 ). While the water supply valve  112  is opened, a proper amount of water is supplied to the ice making tubes  122  of the tray  120  by the water level sensor and the flow amount sensor, etc. These processes are repeatedly performed. In the case of implementing the heater, the operation of the heater is also stopped. 
     Under these configurations, because the ice making unit and the ice separation unit are integrally formed with each other, the entire size of the ice maker may be reduced, and thus a refrigerator having the ice maker may be implemented to have a slim configuration. More specifically, in the conventional art, the tray has a wide width, and the ice separation unit for separating ice from the ice maker has a wide width. Accordingly, the conventional refrigerator having the ice maker has a limitation in having a slim configuration. However, in the present invention, since the ice maker is provided with the tray having a small thickness, an occupation area occupied by the ice maker in the refrigerator is small. 
     Furthermore, since an installation height of the ice maker is lowered, a path for supplying cool air may be shortened. This may prevent loss of cool air being supplied to the ice making chamber. More specifically, in the conventional art, an ice storage container is provided for storing ice made by the ice maker. However, in the present invention, the tray having a long shape in upper and lower directions serves to store a predetermined amount of ice therein, thereby eliminating the need for an additional ice storage container. Accordingly, the ice maker has a lowered installation height, thereby reducing the distance between the freezing chamber and the ice making chamber. This may shorten the path for supplying cool air, thereby reducing loss of cool air, and reducing loss of an input for driving the ice maker. 
     Furthermore, since the ice maker has a simplified configuration and precise operation controls, the fabrication costs may be reduced, and inferiority of the ice maker due to malfunctions may be prevented. More specifically, in the conventional art, ice is separated from the ice maker by a torsion method, a heating method, a rotation method, etc. However, in the present invention, ice is mechanically separated from the ice maker by using a rotation force of the driving motor which rotates the cutter. This may allow the ice maker to have a simplified configuration and precise operation controls. As a result, the fabrication costs for the ice maker may be reduced, and inferiority of the ice maker due to malfunctions may be prevented to enhance reliability of the ice maker. 
     Hereinafter, an ice maker according to another embodiment of the present invention will be explained. 
     In the aforementioned embodiment, one driving motor is used to control the up-down motion of the pistons and the rotation motion of the cutter. However, in another embodiment of the present invention, a driving motor for controlling the up-down motion of the pistons and a driving motor for controlling the rotation motion of the cutter are independently provided from each other. For instance, as shown in  FIG. 9 , a piston moving driving motor  161  may be additionally provided at a lower end of one end of the tray  120 , and a driving gear  162  may be additionally provided at a rotation shaft of the piston moving driving motor  161 . And, a driven gear  163  coupled to the pistons  131  may be coupled to the driving gear  162  so as to be engaged with each other. In an arrangement including a plurality of pistons  131 , the plurality of pistons  131  may be coupled to a first frame  164 , and a second frame  165  may be coupled to the first frame  164  so as to be coupled to the driven gear  163  by a screw. 
     In this case, the ice maker according to this second embodiment has similar configurations and effects as those of the ice maker according to the first embodiment, and thus detailed explanations thereof will be omitted. The ice maker according to the second embodiment where the piston moving driving motor  161  is additionally provided is different from the ice maker according to the first embodiment in that the driving force transmitting member, the worm gears, the worm wheels, etc. need not be provided at a narrow space. This may facilitate the assembly process and controls, and reduce malfunctions of the ice maker as the cutter and the pistons are independently operated. 
     The refrigerator having the ice maker according to the present invention has the following operation and effects. 
     In case of a 3-door bottom freezer type refrigerator having the ice making chamber at the refrigerating chamber and operating the ice maker by guiding cool air to the ice making chamber from the freezing chamber, a space occupied by the ice maker may be reduced, thereby providing a slim configuration of the refrigerator. In case of a built-in refrigerator having a reduced depth in a front-to-rear direction for combination with other structures, a refrigerating chamber door may have a reduced thickness by applying the ice maker thereto. This may enhance a degree of freedom to install the refrigerator. 
     In case of applying the ice maker to the refrigerator, the cutter  141  is installed on an upper end of the tray  120 , thereby discharging the ice from an upper side of the ice maker. Accordingly, as shown in  FIG. 10 , the ice maker  100  may be arranged at a lower side of the refrigerating chamber door  5  beside the dispenser  52  in a width direction at approximately the same height as the dispenser. Alternatively, as shown in  FIG. 11 , the ice maker  100  and the dispenser  52  may be arranged in back and forth directions such that the ice maker  100  is located behind the dispenser  52  in a thickness direction of the refrigerating chamber door  5 . This may reduce a length of a flow path between the freezing chamber  2  and the ice making chamber  51 . Accordingly, loss of cool air that may occur while supplying cool air to the ice making chamber  51  from the freezing chamber  2  may be greatly reduced, thereby lowering power consumption of the refrigerator. This may also increase an effective volume of the refrigerating chamber door. 
     The ice maker, the refrigerator having the same, and the ice making method thereof maybe applicable to all types of refrigerating appliances having ice makers, such as two-door refrigerators, side-by-side refrigerators, and stand-alone freezers without refrigerating chambers. 
     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present disclosure. The present teachings can be readily applied to other types of apparatuses. This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. 
     As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds, are therefore intended to be embraced by the appended claims.