Patent Publication Number: US-2022228786-A1

Title: Ice maker and refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/685,656, filed on Nov. 15, 2019, which claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2018-0142122, filed on Nov. 16, 2018, and Korean Patent Application No. 10-2019-0033192, filed on Mar. 22, 2019, the entire contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to an ice maker and a refrigerator. 
     In general, refrigerators are home appliances for storing foods at a low temperature in a storage space that is covered by a door. 
     The refrigerator may cool the inside of the storage space by using cold air to store the stored food in a refrigerated or frozen state. 
     Generally, an ice maker for making ice is provided in the refrigerator. 
     The ice maker is constructed so that water supplied from a water supply source or a water tank is received in a tray to make ice. 
     Also, the ice maker is constructed to separate the made ice from the ice tray in a heating manner or twisting manner. 
     As described above, the ice maker through which water is automatically supplied and the ice is automatically separated may be opened upward so that the molded ice is pumped up. 
     Ice made in the ice maker of such a structure has at least one surface flat surface, such as a crescent shape or cubic shape. 
     When the ice has a spherical shape, it is more convenient to use the ice, and also, it is possible to provide a different feeling of use to a user. Also, even when the made ice is stored, a contact area between the ice cubes may be minimized to minimize the sticking of the ice cubes. 
     Korean Patent No. 10-1850918 as the Related Art document discloses an ice maker. 
     The ice maker of the Related Art document includes an upper tray in which a plurality of upper cells of a hemispherical shape are arranged and a pair of link guides extending upwardly from both sides are disposed, a lower tray in which a plurality of lower cells of a hemispherical shape are arranged and which is pivotally connected to the upper tray, and an ice-removal heater to heat the upper tray, a rotation shaft which is connected to rear ends of the lower tray and the upper tray and which allows the lower tray to be rotated with respect to the upper tray, a pair of links having an end which is connected to the lower tray and the other end which is connected to the link guide portion, and an upper ejecting pin assembly which is connected to the pair of links, respectively, with both ends fitted to the link guide portion and is lifted and lowered together with the link. 
     The upper ejecting pin assembly is lifted and lowered to separate the ice of the upper tray. Thus, the upper ejecting pin assembly needs to be lifted and lowered in the vertical direction. 
     In addition, the lower tray is rotated to one side for the ice-separation, and then to the other side again for ice-making. In this process, when the upper tray and the lower tray are not completely coupled to each other, there is a problem that a leak occurs in the gap, or the production of spherical ice becomes difficult. 
     In addition, in a case of the prior document, it includes a lower ejecting pin assembly fixed to press the lower tray when the lower tray rotates. 
     By the lower ejecting pin assembly, when the lower tray is pressed, the ice of the lower tray is separated from the lower tray. 
     At this time, as the load applied to the lower ejecting pin assembly increases, there is a possibility that the deformation of the lower ejecting pin assembly occurs. 
     In addition, there may be problems that, due to the tolerance of the motor gear, while the lower tray does not reach the maximum ice-separation position or the lower ejecting pin assembly does not fully press the center of the lower tray, all ice is not separated from the lower tray. 
     In addition, while a plurality of ice is separated at the same time, there is also a problem that the load applied to the motor to rotate the lower tray increases. 
     In addition, there may be a problem that the upper ejecting pin is not inserted into the air hole of the upper tray while the upper ejecting pin assembly flows in the left and right direction or the front and rear direction. 
     SUMMARY 
     According to the present disclosure, there is provided an ice maker and a refrigerator including the same in which, after the lower tray is rotated to a side of the upper tray for ice-making, in a state where the operation of the motor is stopped, while the lower tray is further rotated to a side of the upper tray, the upper tray and the lower tray are more securely coupled to each other. 
     In addition, there is provided an ice maker and a refrigerator including the same which, in the ice-making process, can maintain a state where the upper tray and the lower tray is securely coupled to each other. 
     In addition, there is provided an ice maker and a refrigerator including the same which, when rotating the lower assembly, the upper ejector can be lifted and lowered in the vertical direction while being stably supported. 
     In addition, there is provided an ice maker and a refrigerator including the same in which plastic deformation of the upper tray is prevented despite repeated ice formation. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same in which the deformation of the upper case and the lower case which are fixed to the upper tray is minimized. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same in which the phenomenon of stretching the horizontal extension portion which extends from the upper tray body is prevented. 
     In the present disclosure, there is provided an ice maker and a refrigerator including the same in which while the lower ejecting pin can be in line contact or surface contact with a spherical lower chamber and the contact area therebetween increases, the pressing force can be properly transmitted. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same in which the lower ejecting pin is extended so that the pressing force can be properly transmitted to the center of the spherical lower chamber, and even if the lower assembly does not reach the maximum ice-separation position by the tolerance of the motor gear, a sufficient pressing force is transmitted to the lower chamber. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same which can solve the problem of breaking the ice while the pressing force is concentrated on the ice during the ice-separation. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same in which, when the upper ejector is moved in the vertical direction for the ice-separation, the generation of flow of the upper ejector in the left and right direction or the front and rear direction is prevented and thus the upper ejecting pin is smoothly inserted into an inlet opening of the upper tray. 
     In addition, in the present disclosure, there is provided an ice maker and a refrigerator including the same which is prevented from decreasing the vertical movable distance by the vertical guide for the stable vertical movement of the upper ejector. 
     The ice maker of the present disclosure may include an upper assembly having an upper tray defining a hemispherical upper chamber, and a lower assembly having a lower tray defining a hemispherical lower chamber. 
     The ice maker may be fixed to the housing provided in the freezing chamber of the refrigerator. 
     The upper assembly may be fixed to the housing, and the lower assembly may be rotatably connected to the upper assembly. 
     The upper assembly may further include an upper supporter which contacts the first surface of the upper tray and supports the first surface. 
     In addition, the upper assembly may further include an upper case which is in contact with the second surface of the upper tray and coupled to the upper supporter. 
     The upper tray may include an upper tray body forming the upper chamber and a horizontal extension portion extending in a horizontal direction from the upper tray body. 
     The horizontal extension portion may be located between a portion of the upper supporter and a portion of the upper case. 
     The first surface may be an upper surface of the horizontal extension portion, and the second surface may be a lower surface of the horizontal extension portion. 
     In addition, the ice maker, after completion of ice-making, may further include an upper ejector which includes an upper ejector pin for separating the ice from the top tray. 
     In addition, the upper ejector is connected to the lower assembly to be interlocked with each other, and, when the lower assembly is rotated, the upper ejector may be lifted and lowered. 
     In addition, the ice maker may further include a connection unit which includes a plurality of links and thus connects the upper ejector and the lower assembly to each other, and a driving unit which provides rotational power to the lower assembly. 
     In addition, the connection unit may include a first link for rotating the lower supporter while receiving the power of the drive unit and rotating. 
     In addition, the connection unit may include a second link connecting the lower supporter and the upper ejector and transmitting the rotational force of the lower supporter to the upper ejector when the lower supporter is rotated. 
     In addition, the ice maker may further include an elastic member which connects the first link and the lower supporter to each other and provides a tensile force between the first link and the lower supporter. 
     In addition, the upper ejector may include an ejector body formed in a horizontal direction and a plurality of upper ejecting pins extending from the lower side of the ejector body in a vertical direction. 
     In addition, while the drive unit is operating, when the shaft connection portion rotates, the lower assembly rotates to the first position while rotating upwards, and when the drive unit is stopped, by the tension force of the elastic member, the lower assembly may rotate to a second position higher than the first position. 
     In addition, the upper supporter may include a plurality of unit guides for guiding the vertical movement of the upper ejector. 
     In addition, each unit guide may be provided with a guide slot through which the upper ejector penetrates and which guides the vertical movement of the upper ejector. 
     The ice maker of the present disclosure may include an upper assembly having an upper tray having a hemispherical upper chamber, and a lower assembly having a lower tray having a hemispherical lower chamber. 
     In addition, the upper assembly may include an upper tray having an upper chamber recessed upwardly to define an upper side of the ice chamber in which water is filled to generate ice, an upper supporter which is in contact with the first surface of the upper tray and thus supports the first surface, and an upper case which is in contact with the second surface of the upper tray and coupled to the upper supporter. 
     In addition, the lower assembly may further include a lower tray having a lower chamber recessed downwardly to define a lower side of the ice chamber, a lower supporter supporting a lower side of the lower tray, and a lower case in which a least a portion thereof covers the upper side of the lower tray, and the lower assembly can be rotatably connected to the upper assembly. 
     In addition, after the completion of the ice-making, the ice maker may include an ejector having an ejecting pin for separating the ice from the ice chamber. 
     Spherical ice may be generated by the upper chamber and the lower chamber, and the generated ice may be separated from the upper chamber and the lower chamber by the rotation of the lower assembly. 
     In addition, the ejector may also include an upper ejector having an upper ejecting pin for separating ice from the upper tray and a lower ejector having a lower ejecting pin for separating ice from the lower tray. 
     In addition, the upper ejector may include an upper ejector body formed in a horizontal direction and the upper ejecting pin formed to extend from the lower side of the ejector body in the vertical direction, and both ends of the ejector body may include a separation prevention protrusion in which both sides thereof protrudes in a direction intersecting the ejector body and an upper and lower guide protruding in the same direction as the upper ejecting pin. 
     In addition, the upper and lower guide may be inclined in a direction toward the separation prevention protrusion from the center of the ejector body. 
     In addition, the upper case may include an interference prevention groove into which the upper and lower guide is inserted. 
     In addition, the interference prevention groove may be formed symmetrically in the center of the upper case. 
     In addition, the upper case may include one or more ribs formed adjacent to the interference prevention groove in at least one of the upper direction and the lower direction. 
     In addition, the lower ejector may include a lower ejector body and a plurality of lower ejecting pins protruding from the lower ejector body. 
     In addition, the lower ejecting pin may include a pin body protruding from the lower ejector body and a pressing portion extending from the pin body. 
     In addition, the pin body may be formed in a curved shape. 
     In addition, the pressing portion may be formed with a recessed groove portion in the end portion which is in contact with the lower tray. 
     In addition, the pressing portion may include a pressing inclined portion in contact with the lower tray. 
     In addition, the pin body and the pressing portion may be bent to form a constant angle. 
     A refrigerator according to another aspect may include a cabinet provided with a freezing chamber; a housing provided in the freezing chamber; and an ice maker installed in the housing. 
     The ice maker may include an ejector having an ejecting pin for separating the ice from the ice chamber after the ice-making is completed. 
     According to the proposed invention, there are advantages that, for the ice-making, after the lower tray is rotated to a side of the upper tray, in a state where the operation of the motor is stopped, while the lower tray is further rotated to a side of the upper tray, the upper tray and the lower tray are more reliably coupled to each other. 
     In addition, in the ice-making process, there is an advantage that the upper tray and the lower tray can be securely maintained in a coupled state. 
     In addition, since the unit guide for guiding the upper ejector is provided in the upper supporter, the transfer force of the upper ejector to the upper case can be minimized, and thus deformation of the upper case can be prevented. 
     In addition, there is an advantage that, when rotating the lower assembly, while the upper ejector is securely supported, the upper ejector can be lifted and lowered in the vertical direction. 
     In addition, since ice is produced in the upper tray and the upper tray is fixed by the upper case and the upper supporter, deformation of the upper case and the upper supporter other than the upper tray can be minimized, and the structure of the upper tray, the upper case, and the upper supporter can be simplified. 
     In addition, as the upper tray is formed of a silicone material, plastic deformation of the upper tray can be prevented despite repeated ice formation. 
     In addition, the upper tray may include an upper tray body forming an upper chamber, and a horizontal extension portion extending from the upper tray body, and since the horizontal extension portion is fixed to the upper supporter and the upper case, deformation of the horizontal extension portion can be minimized. 
     In addition, since the upper protrusion and the lower protrusion is provided in the horizontal extension portion and the upper protrusion and the lower protrusion are received in the slots of the upper case and the upper supporter, respectively, it is possible to prevent plastic deformation of the horizontal extension portion. 
     In addition, since an inlet wall is formed around the inlet opening of the upper tray body and the inlet wall is connected to the upper tray body by the connection ribs, the deformation of the inlet wall can be prevented. 
     Since the upper case is fixed to the housing and a water-supply portion is coupled to the upper case, when the deformation of the upper case is prevented, a state where the upper case is fixed to the housing can be stably maintained, and a state where the water-supply portion is coupled to the upper case can be stably maintained. 
     According to the proposed invention, since the upper end portion of the lower ejecting pin is formed to protrude more than the lower end portion, there is an advantage that the upper end portion of the lower ejecting pin can be in line contact or surface contact with the spherical lower chamber and as the contact area increases, the pressing force can be properly transmitted. 
     In addition, there are advantages that the length of the lower ejecting pin is extended so that the pressing force can be properly transmitted to the center of the spherical lower chamber, and a sufficient pressing force is transmitted to the lower chamber even if the lower assembly does not reach the maximum ice-separation position by tolerance of motor gear. 
     In addition, there is an advantage that, when separating ice, although the pressing force is concentrated on the ice, the problem of breaking the ice can be solved. 
     In addition, as the length of the upper and lower guide provided in the upper ejector extends, when the upper ejector moves in the vertical direction for the ice-separation, there are advantages that the flow generation of the upper ejector in the left and right direction and the front and rear direction is prevented and the upper ejector pin is smoothly inserted into the inlet opening of the upper tray. 
     In addition, by including an interference prevention groove corresponding to the upper and lower guide provided in the upper ejector, it is possible to prevent the vertical movement distance of the upper ejector from being reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a refrigerator according to one embodiment of the present disclosure. 
         FIG. 2  is a view illustrating a state where a door of the refrigerator of  FIG. 1  is opened. 
         FIGS. 3A and 3B  are perspective views illustrating an ice maker according to an embodiment of the present disclosure. 
         FIG. 4  is an exploded perspective view illustrating an ice maker according to an embodiment of the present disclosure. 
         FIG. 5A  is a top perspective view illustrating the upper case according to an embodiment of the present disclosure. 
         FIG. 5B  is a plan view of illustrating a portion of an upper case according to an embodiment of the present disclosure. 
         FIG. 5C  is a sectional view taken along line  3 - 3  of  FIG. 5B . 
         FIG. 6  is a bottom perspective view illustrating an upper case according to one embodiment of the present disclosure. 
         FIG. 7  is a top perspective view illustrating an upper tray according to one embodiment of the present disclosure. 
         FIG. 8  is a bottom perspective view illustrating an upper tray according to one embodiment of the present disclosure. 
         FIG. 9  is a side view illustrating an upper tray according to one embodiment of the present disclosure. 
         FIG. 10  is a top perspective view illustrating an upper supporter according to one embodiment of the present disclosure. 
         FIG. 11  is a bottom perspective view illustrating an upper supporter according to one embodiment of the present disclosure. 
         FIG. 12  is an enlarged view illustrating a heater coupling portion in the upper case of  FIG. 5 . 
         FIG. 13  is a view illustrating a state where a heater is coupled to the upper case of  FIG. 5 . 
         FIG. 14  is a view illustrating a layout of an electric wire connected to the heater in the upper case. 
         FIG. 15  is a sectional view illustrating a state where the upper assembly has been assembled. 
         FIG. 16  is a perspective view illustrating the lower assembly according to an embodiment of the present disclosure. 
         FIG. 17  is a top perspective view illustrating a lower case according to one embodiment of the present disclosure. 
         FIG. 18  is a bottom perspective view illustrating a lower case according to one embodiment of the present disclosure. 
         FIG. 19  is a top perspective view illustrating a lower tray according to an embodiment of the present disclosure. 
         FIGS. 20 and 21  are bottom perspective views illustrating a lower tray according to an embodiment of the present disclosure. 
         FIG. 22  is a side view illustrating a lower tray according to one embodiment of the present disclosure. 
         FIG. 23  is a top perspective view illustrating a lower supporter according to one embodiment of the present disclosure. 
         FIG. 24  is a bottom perspective view illustrating the lower supporter according to an embodiment of the present disclosure. 
         FIG. 25  is a sectional view illustrating a state where the lower assembly is assembled. 
         FIG. 26  is a plan view illustrating a lower supporter according to one embodiment of the present disclosure. 
         FIG. 27  is a perspective view illustrating a state where a lower heater is coupled to a lower supporter of  FIG. 26 . 
         FIG. 28  is a view illustrating a state where a lower assembly is coupled to an upper assembly and, at the same time, an electric wire connected to a lower heater penetrates an upper case. 
         FIG. 29  is a cross-sectional view taken along line A-A of  FIG. 3A . 
         FIG. 30  is a view illustrating a state where ice generation is completed in  FIG. 29 . 
         FIG. 31  is a perspective view illustrating the ice maker from which the upper case is removed as viewed from a side. 
         FIG. 32  is a perspective view illustrating the ice maker from which the upper case is removed as viewed from the other side. 
         FIG. 33  is a side view illustrating a state of the lower tray and the upper ejector. 
         FIG. 34  is a side view illustrating a state where the lower tray is rotated and the upper ejector is lowered in the state of  FIG. 33 . 
         FIGS. 35A to 35B  are side views illustrating a state of the additional rotation operation of the lower tray. 
         FIG. 36A to 36C  is a side view illustrating the position of the lower tray according to the rotation angle of the first link. 
         FIG. 37  is a perspective view illustrating a coupling state of the upper ejector and the second link. 
         FIG. 38  is a bottom perspective view illustrating the upper ejector. 
         FIG. 39  is a perspective view illustrating the first link viewed from one side. 
         FIG. 40  is a perspective view illustrating the second link as viewed from the other side. 
         FIG. 41  is a bottom perspective view illustrating a state where the ice maker and the lower ejector are separated according to an embodiment of the present disclosure. 
         FIGS. 42 to 43  are perspective views of the lower ejector illustrated in  FIG. 41  as viewed from various directions. 
         FIG. 44  is a bottom perspective view illustrating a state where the ice maker and the lower ejector are separated according to another embodiment of the present disclosure. 
         FIGS. 45 to 46  are perspective views of the lower ejector illustrated in  FIG. 44  as viewed from various directions. 
         FIG. 47  is a view illustrating the lower ejector according to another embodiment of the present disclosure as viewed from the bottom surface. 
         FIG. 48  is a sectional view taken along the line B-B of  FIG. 3A  in the water-supply state. 
         FIG. 49  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-making state. 
         FIG. 50  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-making state. 
         FIG. 51  is a sectional view taken along the line B-B of  FIG. 3A  in an initial ice-separation state. 
         FIG. 52  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-separation completion state. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are illustrated in different drawings. In addition, in describing the embodiments of the present disclosure, when it is determined that the detailed description of the related well-known configuration or function interferes with the understanding of the embodiments of the present disclosure, the detailed description thereof will be omitted. 
     In addition, in describing the components of the embodiments of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only to distinguish the components from other components, and the nature, order, or the like of the components are not limited by the terms. If a component is described as being “joined”, “coupled” or “connected” to another component, that component may be directly joined, connected to that other component, but it is to be understood that another component may be “joined”, “coupled” or “connected” between each component. 
       FIG. 1  is a perspective view of a refrigerator according to one embodiment of the present disclosure, and  FIG. 2  is a view illustrating a state where a door of the refrigerator of  FIG. 1  is opened. 
     Referring to  FIGS. 1 and 2 , a refrigerator  1  according to an embodiment may include a cabinet  2  defining a storage space and a door that opens and closes the storage space. 
     In detail, the cabinet  2  may define the storage space that is vertically divided by a barrier. Here, a refrigerating compartment  3  may be defined at an upper side, and a freezing compartment  4  may be defined at a lower side. 
     Receiving members such as a drawer, a shelf, a basket, and the like may be provided in the refrigerating chamber  3  and the freezing chamber  4 . 
     The door may include a refrigerating chamber door  5  opening/closing the refrigerating chamber  3  and a freezing chamber door  6  opening/closing the freezing chamber  4 . 
     The refrigerating chamber door  5  may be constituted by a pair of left and right doors and be opened and closed through rotation thereof. In addition, the freezing chamber door  6  may be inserted and withdrawn in a drawer manner. 
     Alternatively, the arrangement of the refrigerating chamber  3  and the freezing chamber  4  and the shape of the door may be changed according to kinds of refrigerators, but are not limited thereto. For example, the embodiments may be applied to various kinds of refrigerators. For example, the freezing chamber  4  and the refrigerating chamber  3  may be disposed at left and right sides, or the freezing chamber  4  may be disposed above the refrigerating chamber  3 . 
     An ice maker  100  may be provided in the freezing chamber  4 . The ice maker  100  is constructed to make ice by using supplied water. Here, the ice may have a spherical shape. 
     In addition, an ice bin  102  in which the made ice is stored after being separated from the ice maker  100  may be further provided below the ice maker  100 . 
     The ice maker  100  and the ice bin  102  may be mounted in the freezing chamber  4  in a state of being respectively received in separate housings  101 . 
     A user may open the refrigerating chamber door  6  to approach the ice bin  102 , thereby obtaining the ice. 
     For another example, a dispenser  7  for dispensing purified water or the made ice to the outside may be provided in the refrigerating chamber door  5 . 
     Also, the ice made in the ice maker  100  or the ice stored in the ice bin  102  after being made in the ice maker  100  may be transferred to the dispenser  7  by a transfer unit. Thus, the user may obtain the ice from the dispenser  7 . 
     Hereinafter, the ice maker will be described in detail with reference to the accompanying drawings. 
       FIGS. 3 a  and 3 b    are perspective views illustrating an ice maker according to an embodiment of the present disclosure, and  FIG. 4  is an exploded perspective view illustrating an ice maker according to an embodiment of the present disclosure. 
     Referring to  FIGS. 3 a    to  4 , the ice maker  100  may include an upper assembly  110  and a lower assembly  200 . 
     The lower assembly  200  may rotate with respect to the upper assembly  110 . For example, the lower assembly  200  may be connected to be rotatable with respect to the upper assembly  110 . 
     In a state where the lower assembly  200  contacts the upper assembly  110 , the lower assembly  200  together with the upper assembly  110  may make spherical ice. 
     In other words, the upper assembly  110  and the lower assembly  200  may define an ice chamber  111  for making the spherical ice. The ice chamber  111  may have a chamber having a substantially spherical shape. 
     The upper assembly  110  and the lower assembly  200  may define a plurality of ice chambers  111 . 
     Hereinafter, a structure in which three ice chambers are defined by the upper assembly  110  and the lower assembly  200  will be described as an example, and also, the embodiments are not limited to the number of ice chambers  111 . 
     In the state where the ice chamber  111  is defined by the upper assembly  110  and the lower assembly  200 , water is supplied to the ice chamber  111  through a water supply portion  190 . 
     The water supply portion  190  is coupled to the upper assembly  110  to guide water supplied from the outside to the ice chamber  111 . 
     After the ice is made, the lower assembly  200  may rotate in a forward direction. Thus, the spherical ice made between the upper assembly  110  and the lower assembly  200  may be separated from the upper assembly  110  and the lower assembly  200 . 
     The ice maker  100  may further include a driving unit  180  so that the lower assembly  200  is rotatable with respect to the upper assembly  110 . 
     The driving unit  180  may include a driving motor and a power transmission portion for transmitting power of the driving motor to the lower assembly  200 . The power transmission portion may include one or more gears. 
     The driving motor may be a bi-directional rotatable motor. Thus, the lower assembly  200  may rotate in both directions. 
     The ice maker  100  may further include an upper ejector  300  so that the ice is capable of being separated from the upper assembly  110 . 
     When the upper ejector  300  is connected to the lower assembly  200  so as to be interlocked with the lower assembly and thus the lower assembly  200  rotates, the upper ejector  300  can be lifted and lowered. 
     For example, after the ice-making completion, if the lower assembly  200  is rotated downward to be spaced apart from the upper assembly  110 , the upper ejector  300  can be lowered. 
     In addition, after the ice-separation completion, when the lower assembly  200  is rotated upward to be coupled with the upper assembly  110  for water-supply, the upper ejector  300  may be lifted. 
     At the time of the ice-separation, when the upper ejector  300  is lowered, the ice that is in close contact with the upper assembly  110  may be separated from the upper assembly  110 . 
     The upper ejector  300  may include an upper ejector body  310  and a plurality of upper ejecting pins  320  extending in a direction intersecting the upper ejector body  310 . 
     For example, the ejector body  310  may be formed in a horizontal direction, and the upper ejecting pin  320  may be formed to extend in a vertical direction from the lower side of the ejector body  130 . 
     A plurality of grooves may be formed in the ejector body  310  along the longitudinal direction. A plurality of reinforcing ribs  311  may be formed in the groove. The reinforcing rib  311  may be formed in parallel to the longitudinal direction of the ejector body  310 . In addition, the reinforcing rib  311  may be formed in a direction intersecting the longitudinal direction of the ejector body  310 . 
     In addition, the upper ejecting pin  320  may be formed with a hollow  321 . Thus, the strength of the upper ejecting pin  320  can be improved. 
     In addition, for the ice-separation, when the lower end of the upper ejecting pin  320  presses the spherical upper tray  150 , that is, an upper side of the ice chamber  111 , the stable contact is possible by the hollow  321 . 
     The upper ejecting pins  320  may be provided in the same number of ice chambers  111 . 
     A separation prevention protrusion  312  for preventing a connection unit  350  from being separated in the state of being coupled to the connection unit  350  that will be described later may be provided on each of both ends of the ejector body  310 . 
     For example, the pair of separation prevention protrusions  312  may protrude in opposite directions from the ejector body  310 . 
     In detail, both ends of the ejector body  310  may be formed with a separation prevention protrusion  312  in which both sides thereof protrude in a direction intersecting the ejector body  310 . 
     The separation prevention protrusion  312  may include a circular central portion  312   a  and a pair of protrusion portions  312   b  protruding in the radial direction of the central portion  312   a  from both sides of the central portion  312   a.    
     While the upper ejecting pin  320  passing through the upper assembly  110  and inserted into the ice chamber  111 , the ice within the ice chamber  111  may be pressed. 
     The ice pressed by the upper ejecting pin  320  may be separated from the upper assembly  110 . 
     Also, the ice maker  100  may further include a lower ejector  400  so that the ice closely attached to the lower assembly  200  is capable of being separated. 
     The lower ejector  400  may press the lower assembly  200  to separate the ice closely attached to the lower assembly  200  from the lower assembly  200 . For example, the lower ejector  400  may be fixed to the upper assembly  110 . 
     The lower ejector  400  may include a lower ejector body  410  and a plurality of lower ejecting pins  420  protruding from the lower ejector body  410 . The lower ejecting pins  420  may be provided in the same number of ice chambers  111 . 
     In addition, the lower ejecting pin  420  may include a pin body  420   a  protruding from the lower ejector body  410  and a pressing portion  420   b  extending from the pin body  420   a.    
     For example, the pin body  420   a  and the pressing portion  420   b  may be bent to form a predetermined angle, and the pressing portion  420   b  may extend from the pin body  420   a  so as to press the center of the ice chamber  111 . 
     While the lower assembly  200  rotates to separate the ice, rotation force of the lower assembly  200  may be transmitted to the upper ejector  300 . 
     For this, the ice maker  100  may further include the connection unit  350  connecting the lower assembly  200  to the upper ejector  300 . The connection unit  350  may include one or more links. 
     For example, when the lower assembly  200  rotates in one direction, the upper ejector  300  may descend by the connection unit  350  to allow the upper ejector pin  320  to press the ice. 
     On the other hand, when the lower assembly  200  rotates in the other direction, the upper ejector  300  may ascend by the connection unit  350  to return to its original position. 
     Hereinafter, the upper assembly  110  and the lower assembly  120  will be described in more detail. 
     The upper assembly  110  may include an upper tray  150  defining a portion of the ice chamber  111  making the ice. For example, the upper tray  150  may define an upper portion of the ice chamber  111 . 
     The upper assembly  110  may further include an upper case  120  and an upper supporter  170  fixing a position of the upper tray  150 . 
     The upper tray  150  may be disposed below the upper case  120 . A portion of the upper supporter  170  may be disposed below the upper tray  150 . 
     As described above, the upper case  120 , the upper tray  150 , and the upper supporter  170 , which are vertically aligned, may be coupled to each other through a fastening member. 
     In other words, the upper tray  150  may be fixed to the upper case  120  through the fastening of the fastening member. 
     In addition, the upper supporter  170  may support the lower side of the upper tray  150  to limit the downward movement. 
     For example, the water supply portion  190  may be fixed to the upper case  120 . 
     The ice maker  100  may further include a temperature sensor  500  detecting a temperature of the upper tray  150 . 
     For example, the temperature sensor  500  may be mounted on the upper case  120 . Also, when the upper tray  150  is fixed to the upper case  120 , the temperature sensor  500  may contact the upper tray  150 . 
     Meanwhile, the lower assembly  200  may include a lower tray  250  defining the other portion of the ice chamber  111  making the ice. For example, the lower tray  250  may define a lower portion of the ice chamber  111 . 
     The lower assembly  200  may further include a lower supporter  270  supporting a lower portion of the lower tray  250  and a lower case  210  of which at least a portion covers an upper side of the lower tray  250 . 
     The lower case  210 , the lower tray  250 , and the lower supporter  270  may be coupled to each other through a fastening member. 
     The ice maker  100  may further include a switch for turning on/off the ice maker  100 . When the user turns on the switch  600 , the ice maker  100  may make ice. 
     In other words, when the switch  600  is turned on, water may be supplied to the ice maker  100 . Then, an ice-making process of making ice by using cold air and an ice-separation process of separating the ice through the rotation of the lower assembly  200  can be performed repeatedly. 
     On the other hand, when the switch  600  is manipulated to be turned off, the making of the ice through the ice maker  100  may be impossible. For example, the switch  600  may be provided in the upper case  120 . 
     &lt;Upper Case&gt; 
       FIG. 5A  is a top perspective view illustrating the upper case according to an embodiment of the present disclosure,  FIG. 5B  is a plan view of illustrating a portion of an upper case according to an embodiment of the present disclosure,  FIG. 5C  is a sectional view taken along line  3 - 3  of  FIG. 5B , and  FIG. 6  is a bottom perspective view illustrating an upper case according to one embodiment of the present disclosure. Referring to  FIGS. 5 and 6 , the upper case  120  may be fixed to a housing  101  within the freezing chamber  4  in a state where the upper tray  150  is fixed. 
     The upper case  120  may include an upper plate for fixing the upper tray  150 . 
     The upper tray  150  may be fixed to the upper plate  121  in a state where a portion of the upper tray  150  contacts a bottom surface of the upper plate  121 . 
     An opening  123  through which a portion of the upper tray  150  passes may be defined in the upper plate  121 . 
     For example, when the upper tray  150  is fixed to the upper plate  121  in a state where the upper tray  150  is disposed below the upper plate  121 , a portion of the upper tray  150  may protrude upward from the upper plate  121  through the opening  123 . 
     Alternatively, the upper tray  150  may not protrude upward from the upper plate  121  through opening  123  but protrude downward from the upper plate  121  through the opening  123 . 
     The upper plate  121  may include a through-opening ( 139   a  and  139   b  of  FIG. 5A ) into which the plurality of unit guides  181  and  182  of the upper supporter  170  to be described later is introduced. 
     In addition, the upper plate  121  may include interference prevention grooves  126   a  and  126   b.    
     The opening  123  may be located between the pair of interference prevention grooves  126   a  and  126   b.    
     The interference device grooves  126   a  and  126   b  have a configuration into which a portion of the upper and lower guide  313  to be described later may be inserted so as to prevent interference with the upper plate  121  when the upper ejector  300  moves up and down along the unit guides  181  and  182 . 
     In detail, the interference prevention grooves  126   a  and  126   b  may have a width corresponding to a width of a portion of the upper and lower guide  313  which is inserted therein, correspond to the through-openings  139   a  and  139   b  positioned at both sides of the upper plate  121 , and be formed symmetrically with respect to the opening  123 . 
     In addition, it can be prevented the vertical movement distance of the upper ejector  300  from decreasing by receiving the lower portion of the vertical guide  313  in the interference prevention grooves  126   a  and  126   b  in a process of lowering the upper ejector  300 . 
     The upper plate  121  may include a recessed portion  122  that is recessed downward. The opening  123  may be defined in a bottom surface  122   a  of the recessed portion  122 . 
     Thus, the upper tray  150  passing through the opening  123  may be disposed in a space defined by the recessed portion  122 . 
     A heater coupling portion  124  for coupling an upper heater  148  that heats the upper tray  150  so as to separate the ice may be provided in the upper case  120 . 
     For example, the heater coupling portion  124  may be provided on the upper plate  121 . The heater coupling portion  124  may be disposed below the recessed portion  122 . 
     The upper case  120  may further include a switch case  125  for installing the switch  600 . 
     The switch case  125  may be connected to the side circumference portion  143  which will be described later and may be provided at the lower end of the upper plate  121  and may include one or more holes for installing the switch  600 . 
     The upper case  120  may further include a plurality of installation ribs  128  and  129  for installing the temperature sensor  500 . 
     The pair of installation ribs  128  and  129  may be disposed to be spaced apart from each other in a direction of an arrow B of  FIG. 6 . The pair of installation ribs  128  and  129  may be disposed to face each other, and the temperature sensor  500  may be disposed between the pair of installation ribs  128  and  129 . 
     The pair of installation ribs  128  and  129  may be provided on the upper plate  121 . 
     A plurality of slots  131  and  132  coupled to the upper tray  150  may be provided in the upper plate  121 . 
     A portion of the upper tray  150  may be inserted into the plurality of slots  131  and  132 . 
     The plurality of slots  131  and  132  may include a first upper slot  131  and a second upper slot  132  disposed at an opposite side of the first upper slot  131  with respect to the opening  123 . 
     The opening  123  may be defined between the first upper slot  131  and the second upper slot  132 . 
     The first upper slot  131  and the second upper slot  132  may be spaced apart from each other in a direction of an arrow B of  FIG. 6 . 
     Although not limited, the plurality of first upper slots  131  may be arranged to be spaced apart from each other in a direction of an arrow A (hereinafter, referred to as a first direction) that a direction crossing a direction of an arrow B (hereinafter, referred to as a second direction). 
     Also, the plurality of second upper slots  132  may be arranged to be spaced apart from each other in the direction of the arrow A. 
     In this specification, the direction of the arrow A may be the same direction as the arranged direction of the plurality of ice chambers  111 . 
     For example, the first upper slot  131  may be defined in a curved shape. Thus, the first upper slot  131  may increase in length. 
     For example, the second upper slot  132  may be defined in a curved shape. Thus, the second upper slot  133  may increase in length. 
     When each of the upper slots  131  and  132  increases in length, a protrusion (that is disposed on the upper tray) inserted into each of the upper slots  131  and  132  may increase in length to improve coupling force between the upper tray  150  and the upper case  120 . 
     A distance between the first upper slot  131  and the opening  123  may be different from that between the second upper slot  132  and the opening  123 . For example, the distance between the first upper slot  131  and the opening  123  may be greater than that between the second upper slot  132  and the opening  123 . 
     In addition, when viewed from the opening  123  toward each of the upper slots  131 , a shape that is convexly rounded from each of the slots  131  toward the outside of the opening  123  may be provided. 
     The upper plate  121  may further include a sleeve  133  into which a fastening boss of the upper supporter, which will be described later, is inserted. 
     The sleeve  133  may have a cylindrical shape and extend upward from the upper plate  121 . 
     For example, a plurality of sleeves  133  may be provided on the upper plate  121 . The plurality of sleeves  133  may be arranged to be spaced apart from each other in the direction of the arrow A. Also, the plurality of sleeves  133  may be arranged in a plurality of rows in the direction of the arrow B. 
     A portion of the plurality of sleeves may be disposed between the two first upper slots  131  adjacent to each other. 
     The other portion of the plurality of sleeves may be disposed between the two second upper slots  132  adjacent to each other or be disposed to face a region between the two second upper slots  132 . 
     The upper case  120  may further include a plurality of hinge supporters  135  and  136  allowing the lower assembly  200  to rotate. 
     The plurality of hinge supporters  135  and  136  may be disposed to be spaced apart from each other in the direction of the arrow A with respect to  FIG. 6 . In addition, a first hinge hole  137  may be defined in each of the hinge supporters  135  and  136 . 
     For example, the plurality of hinge supporters  135  and  136  may extend downward from the upper plate  121 . 
     The upper case  120  may further include a vertical extension portion  140  vertically extending along a circumference of the upper plate  121 . The vertical extension portion  140  may extend upward from the upper plate  121 . 
     The vertical extension portion  140  may include one or more coupling hooks  140   a.  The upper case  120  may be hook-coupled to the housing  101  by the coupling hooks  140   a.    
     In addition, the water supply portion  190  may be coupled to the vertical extension portion  140 . 
     The upper case  120  may further include the upper rib  141   a,    141   b,  and  141   c  in order to prevent the problem that the strength and durability can be weakened by forming the interference prevention grooves  126   a  and  126   b  adjacent to the through-openings  139   a  and  139   b.    
     The upper ribs  141   a,    141   b,  and  141   c  may extend from the upper plate  121 , and a plurality of the upper ribs  141   a,    141   b,  and  141   c  may be formed upward or downward of the upper plate  121  as long as there is no interference in assembling the upper assembly  110 . 
     The upper ribs  141   a,    141   b,  and  141   c  may include the first upper rib to the third upper rib  141   a,    141   b,  and  141   c.    
     The first upper rib  141   a  and the second upper rib  141   b  may be formed at positions symmetrical with respect to the opening  123  adjacent to the interference prevention grooves  126   a  and  126   b.    
     In addition, the first and second upper ribs  141   a  and  141   b  may be formed to extend upward from the upper plate  121  in one bent shape. 
     In detail, the first and second upper ribs  141   a  and  141   b  may be vertically formed along the circumference of the through-openings  139   a  and  139   b  formed in the upper plate  121  at positions adjacent to the interference prevention grooves  126   a  and  126   b.    
     In addition, the first and second upper ribs  141   a  and  141   b  may be formed only on one side surface of the interference prevention grooves  126   a  and  126   b  so as to prevent interference by the assembly of the upper supporter  170  and the connection unit  350 . 
     In addition, one of the first and second upper ribs  141   a  and  141   b  may have a shape in which the height increases toward the outside of the upper plate  121 . 
     The third upper rib  141   c  may be formed to extend downward from the upper plate  121 . 
     In detail, the third upper rib  141   c  may be formed to connect the switch case  125  and the recessed portion  122  to support the switch case  125  that protrudes. In a case of the structure protruding by the third upper rib  141   c,  the problem that the durability or strength that may occur may be weakened can be solved. 
     The upper case  120  may further include a horizontal extension portion  142  horizontally extending to the outside of the vertical extension portion  140 . 
     A screw fastening portion  142   a  protruding outward to screw-couple the upper case  120  to the housing  101  may be provided on the horizontal extension portion  142 . 
     The upper case  120  may further include a side circumferential portion  143 . The side circumferential portion  143  may extend downward from the horizontal extension portion  142 . 
     The side circumferential portion  143  may be disposed to surround a circumference of the lower assembly  200 . In other words, the side circumferential portion  143  may prevent the lower assembly  200  from being exposed to the outside. 
     Although the upper case is coupled to the separate housing  101  within the freezing chamber  4  as described above, the embodiment is not limited thereto. For example, the upper case  120  may be directly coupled to a wall defining the freezing chamber  4 . 
     &lt;Upper Tray&gt; 
       FIG. 7  is a top perspective view illustrating an upper tray according to one embodiment of the present disclosure,  FIG. 8  is a bottom perspective view illustrating an upper tray according to one embodiment of the present disclosure, and  FIG. 9  is a side view illustrating an upper tray according to one embodiment of the present disclosure. 
     Referring to  FIGS. 7 to 9 , the upper tray  150  may be made of a flexible material that is capable of being restored to its original shape after being deformed by an external force. 
     For example, the upper tray  150  may be made of a silicone material. Like this embodiment, when the upper tray  150  is made of the silicone material, even though external force is applied to deform the upper tray  150  during the ice-separation process, the upper tray  150  may be restored to its original shape. Thus, in spite of repetitive ice-making, spherical ice may be made. 
     If the upper tray  150  is made of a metal material, when the external force is applied to the upper tray  150  to deform the upper tray  150  itself, the upper tray  150  may not be restored to its original shape any more. 
     In this case, after the upper tray  150  is deformed in shape, the spherical ice may not be made. In other words, it is impossible to repeatedly make the spherical ice. 
     On the other hand, like this embodiment, when the upper tray  150  is made of the flexible material that is capable of being restored to its original shape, this limitation may be solved. 
     Also, when the upper tray  150  is made of the silicone material, the upper tray  150  may be prevented from being melted or thermally deformed by heat provided from an upper heater. 
     The upper tray  150  may include an upper tray body  151  defining an upper chamber  152  that is a portion of the ice chamber  111 . 
     The upper tray body  151  may define a plurality of upper chambers  152 . 
     For example, the plurality of upper chambers  152  may define a first upper chamber  152   a,  a second upper chamber  152   b,  and a third upper chamber  152   c.    
     The upper tray body  151  may include three chamber walls  153  defining three independent upper chambers  152   a,    152   b,  and  152   c.  The three chamber walls  153  may be connected to each other to form one body. 
     The first upper chamber  152   a,  the second upper chamber  152   b,  and the third upper chamber  152   c  may be arranged in a line. For example, the first upper chamber  152   a,  the second upper chamber  152   b,  and the third upper chamber  152   c  may be arranged in a direction of an arrow A with respect to  FIG. 8 . The direction of the arrow A of  FIG. 8  may be the same direction as the direction of the arrow A of  FIG. 6 . 
     The upper chamber  152  may have a hemispherical shape. In other words, an upper portion of the spherical ice may be made by the upper chamber  152 . 
     An inlet opening  154  through which water is introduced into the upper chamber may be defined in an upper side of the upper tray body  151 . For example, three inlet openings  154  may be defined in the upper tray body  151 . Cold air may be guided into the ice chamber  111  through the inlet opening  154 . 
     In the ice-separation process, the upper ejector  300  may be inserted into the upper chamber  152  through the inlet opening  154 . 
     While the upper ejector  300  is inserted through the inlet opening  154 , an inlet wall  155  may be provided on the upper tray  150  to minimize deformation of the inlet opening  154  in the upper tray  150 . 
     The inlet wall  155  may be disposed along a circumference of the inlet opening  154  and extend upward from the upper tray body  151 . 
     The inlet wall  155  may have a cylindrical shape. Thus, the upper ejector  30  may pass through the inlet opening  154  via an inner space of the inlet wall  155 . 
     One or more first connection ribs  155   a  may be provided along a circumference of the inlet wall  155  to prevent the inlet wall  155  from being deformed while the upper ejector  300  is inserted into the inlet opening  154 . 
     The first connection rib  155   a  may connect the inlet wall  155  to the upper tray body  151 . For example, the first connection rib  155   a  may be integrated with the circumference of the inlet wall  155  and an outer face of the upper tray body  151 . 
     Although not limited, the plurality of connection ribs  155   a  may be disposed along the circumference of the inlet wall  155 . 
     The two inlet walls  155  corresponding to the second upper chamber  152   b  and the third upper chamber  152   c  may be connected to each other through the second connection rib  162 . The second connection rib  162  may also prevent the inlet wall  155  from being deformed. 
     A water supply guide  156  may be provided in the inlet wall  155  corresponding to one of the three upper chambers  152   a,    152   b,  and  152   c.    
     Although not limited, the water supply guide  156  may be provided in the inlet wall corresponding to the second upper chamber  152   b.    
     The water supply guide  156  may be inclined upward from the inlet wall  155  in a direction which is away from the second upper chamber  152   b.    
     The upper tray  150  may further include a first receiving portion  160 . The recessed portion  122  of the upper case  120  may be received in the first receiving portion  160 . 
     A heater coupling portion  124  may be provided in the recessed portion  122 , and an upper heater (see reference numeral  148  of  FIG. 13 ) may be provided in the heater coupling portion  124 . Thus, it may be understood that the upper heater (see reference numeral  148  of  FIG. 13 ) is received in the first receiving portion  160 . 
     The first receiving portion  160  may be disposed in a shape that surrounds the upper chambers  152   a,    152   b,  and  152   c.  The first receiving portion  160  may be provided by recessing a top surface of the upper tray body  151  downward. 
     The heater coupling portion  124  to which the upper heater (see reference numeral  148  of  FIG. 13 ) is coupled may be received in the first receiving portion  160 . 
     The upper tray  150  may further include a second receiving portion  161  (or referred to as a sensor receiving portion) in which the temperature sensor  500  is received. 
     For example, the second receiving portion  161  may be provided in the upper tray body  151 . Although not limited, the second receiving portion  161  may be provided by recessing a bottom surface of the first receiving portion  160  downward. 
     In addition, the second receiving portion  161  may be disposed between the two upper chambers adjacent to each other. For example, in  FIG. 7 , the second receiving portion  161  may be disposed between the first upper chamber  152   a  and the second upper chamber  152   b.    
     Thus, an interference between the upper heater (see reference numeral  148  of  FIG. 13 ) received in the first receiving portion  160  and the temperature sensor  500  may be prevented. 
     In the state where the temperature sensor  500  is received in the second receiving portion  161 , the temperature sensor  500  may contact an outer face of the upper tray body  151 . 
     The chamber wall  153  of the upper tray body  151  may include a vertical wall  153   a  and a curved wall  153   b.    
     The curved wall  153   b  may be rounded upward in a direction that is away from the upper chamber  152 . 
     The upper tray  150  may further include a horizontal extension portion  164  horizontally extending from the circumference of the upper tray body  151 . For example, the horizontal extension portion  164  may extend along a circumference of an upper edge of the upper tray body  151 . 
     The horizontal extension portion  164  may contact the upper case  120  and the upper supporter  170 . 
     For example, a bottom surface  164   b  (or referred to as a “first surface”) of the horizontal extension portion  164  may contact the upper supporter  170 , and a top surface  164   a  (or referred to as a “second surface”) of the horizontal extension portion  164  may contact the upper case  120 . 
     At least a portion of the horizontal extension portion  164  may be disposed between the upper case  120  and the upper supporter  170 . 
     The horizontal extension portion  164  may include a plurality of upper protrusions  165  and  166  respectively inserted into the plurality of upper slots  131  and  132 . 
     The plurality of upper protrusions  165  and  166  may include a first upper protrusion  165  and a second upper protrusion  166  disposed at an opposite side of the first upper protrusion  165  with respect to the inlet opening  154 . 
     The first upper protrusion  165  may be inserted into the first upper slot  131 , and the second upper protrusion  166  may be inserted into the second upper slot  132 . 
     The first upper protrusion  165  and the second upper protrusion  166  may protrude upward from the top surface  164   a  of the horizontal extension portion  164 . 
     The first upper protrusion  165  and the second upper protrusion  166  may be spaced apart from each other in the direction of the arrow B of  FIG. 8 . The direction of the arrow B of  FIG. 8  may be the same direction as the direction of the arrow B of  FIG. 6 . 
     Although not limited, the plurality of first upper protrusions  165  may be arranged to be spaced apart from each other in the direction of the arrow A. 
     In addition, the plurality of second upper protrusions  166  may be arranged to be spaced apart from each other in the direction of the arrow A. 
     For example, the first upper protrusion  165  may be provided in a curved shape. Also, for example, the second upper protrusion  166  may be provided in a curved shape. 
     In this embodiment, each of the upper protrusions  165  and  166  may be constructed so that the upper tray  150  and the upper case  120  are coupled to each other, and also, the horizontal extension portion is prevented from being deformed during the ice-making process or the ice-separation process. 
     Here, when each of the upper protrusions  165  and  166  is provided in the curved shape, distances between the upper protrusions  165  and  166  and the upper chamber  152  in a longitudinal direction of the upper protrusions  165  and  166  may be equal or similar to each other to effectively prevent the horizontal extension portions  264  from being deformed. 
     For example, the deformation in the horizontal direction of the horizontal extension portion  264  may be minimized to prevent the horizontal extension portion  264  from being plastic-deformed. If when the horizontal extension portion  264  is plastic-deformed, since the upper tray body is not positioned at the correct position during the ice-making, the shape of the ice may not close to the spherical shape. 
     The horizontal extension portion  164  may further include a plurality of lower protrusions  167  and  168 . The plurality of lower protrusions  167  and  168  may be inserted into a lower slot of the upper supporter  170 , which will be described below. 
     The plurality of lower protrusions  167  and  168  may include a first lower protrusion  167  and a second lower protrusion  168  disposed at an opposite side of the first lower protrusion  167  with respect to the upper chamber  152 . 
     The first lower protrusion  167  and the second lower protrusion  168  may protrude upward from the bottom surface  164   b  of the horizontal extension portion  164 . 
     The first lower protrusion  167  may be disposed at an opposite to the first upper protrusion  165  with respect to the horizontal extension portion  164 . The second lower protrusion  168  may be disposed at an opposite side of the second upper protrusion  166  with respect to the horizontal extension portion  164 . 
     The first lower protrusion  167  may be spaced apart from the vertical wall  153   a  of the upper tray body  151 . The second lower protrusion  168  may be spaced apart from the curved wall  153   b  of the upper tray body  151 . 
     Each of the plurality of lower protrusions  167  and  168  may also be provided in a curved shape. Since the protrusions  165 ,  166 ,  167 , and  168  are disposed on each of the top and bottom surfaces  164   a  and  164   b  of the horizontal extension portion  164 , the deformation in the horizontal direction of the horizontal extension portion  164  may be effectively prevented. 
     A through-hole  169  through which the fastening boss of the upper supporter  170 , which will be described later, may be provided in the horizontal extension portion  164 . 
     For example, a plurality of through-holes  169  may be provided in the horizontal extension portion  164 . 
     A portion of the plurality of through-holes  169  may be disposed between the two first upper protrusions  165  adjacent to each other or the two first lower protrusions  167  adjacent to each other. 
     The other portion of the plurality of through-holes  169  may be disposed between the two second lower protrusions  168  adjacent to each other or be disposed to face a region between the two second lower protrusions  168 . 
     &lt;Upper Supporter&gt; 
       FIG. 10  is a top perspective view illustrating an upper supporter according to one embodiment of the present disclosure, and  FIG. 11  is a bottom perspective view illustrating an upper supporter according to one embodiment of the present disclosure. 
     Referring to  FIGS. 10 and 11 , the upper supporter  170  may include a supporter plate  171  contacting the upper tray  150 . 
     For example, a top surface of the supporter plate  171  may contact the bottom surface  164   b  of the horizontal extension portion  164  of the upper tray  150 . 
     A plate opening  172  through which the upper tray body  151  passes may be defined in the supporter plate  171 . 
     A circumferential wall  174  that is bent upward may be provided on an edge of the supporter plate  171 . For example, the circumferential wall  174  may contact at least a portion of a circumference of a side surface of the horizontal extension portion  164 . 
     In addition, a top surface of the circumferential wall  174  may contact a bottom surface of the upper plate  121 . 
     The supporter plate  171  may include a plurality of lower slots  176  and  177 . 
     The plurality of lower slots  176  and  177  may include a first lower slot  176  into which the first lower protrusion  167  is inserted and a second lower slot  177  into which the second lower protrusion  168  is inserted. 
     The plurality of first lower slots  176  may be disposed to be spaced apart from each other in the direction of the arrow A on the supporter plate  171 . Also, the plurality of second lower slots  177  may be disposed to be spaced apart from each other in the direction of the arrow A on the supporter plate  171 . 
     The supporter plate  171  may further include a plurality of fastening bosses  175 . The plurality of fastening bosses  175  may protrude upward from the top surface of the supporter plate  171 . 
     Each of the fastening bosses  175  may pass through the through-hole  169  of the horizontal extension portion  164  and be inserted into the sleeve  133  of the upper case  120 . 
     In the state where the fastening boss  175  is inserted into the sleeve  133 , a top surface of the fastening boss  175  may be disposed at the same height as a top surface of the sleeve  133  or disposed at a height lower than that of the top surface of the sleeve  133 . 
     A fastening member coupled to the fastening boss  175  may be, for example, a bolt (see reference symbol B 1  of  FIG. 3 ). The bolt B 1  may include a body portion and a head portion having a diameter greater than that of the body portion. The bolt B 1  may be coupled to the fastening boss  175  from an upper side of the fastening boss  175 . 
     While the body portion of the bolt B 1  is coupled to the fastening boss  175 , when the head portion contacts the top surface of the sleeve  133 , and the head portion contacts the top surface of the sleeve  133  and the top surface of the fastening boss  175 , assembling of the upper assembly  110  may be completed. 
     The upper supporter  170  may further include a plurality of unit guides  181  and  182  for guiding the connection unit  350  connected to the upper ejector  300 . 
     The plurality of unit guides  181  and  182  may be, for example, disposed to be spaced apart from each other in the direction of the arrow A with respect to  FIG. 11 . 
     The unit guides  181  and  182  may extend upward from the top surface of the supporter plate  171 . In addition, each of the unit guides  181  and  182  may be connected to the circumferential wall  174 . 
     Each of the unit guides  181  and  182  may include a guide slot  183  vertically extends. 
     In a state where both ends of the ejector body  310  of the upper ejector  300  pass through the guide slot  183 , the connection unit  350  is connected to the ejector body  310 . 
     Thus, when the rotation force is transmitted to the ejector body  310  by the connection unit  350  while the lower assembly  200  rotates, the ejector body  310  may vertically move along the guide slot  183 . 
     &lt;Upper Heater Coupling Structure&gt; 
       FIG. 12  is an enlarged view illustrating a heater coupling portion in the upper case of  FIG. 5 ,  FIG. 13  is a view illustrating a state where a heater is coupled to the upper case of  FIG. 5 , and  FIG. 14  is a view illustrating a layout of an electric wire connected to the heater in the upper case. 
     Referring to  FIGS. 12 to 14 , the heater coupling portion  124  may include a heater receiving groove  124   a  accommodating the upper heater  148 . 
     For example, the heater receiving groove  124   a  may be defined by recessing a portion of a bottom surface of the recessed portion  122  of the upper case  120  upward. 
     The heater receiving groove  124   a  may extend along a circumference of the opening  123  of the upper case  120 . 
     For example, the upper heater  148  may be a wire-type heater. Thus, the upper heater  148  may be bendable. The upper heater  148  may be bent to correspond to a shape of the heater receiving groove  124   a  so as to accommodate the upper heater  148  in the heater receiving groove  124   a.    
     The upper heater  148  may be a DC heater receiving DC power. The upper heater  148  may be turned on to separate ice. When the heat of the upper heater  148  is transferred to the upper tray  150 , ice may be separated from the surface (which is an inner surface) of the upper tray  150 . At this time, as the heat of the upper heater  148  is stronger, the portion of the spherical ice facing the upper heater  148  becomes opaque than other portions. In other words, an opaque band of a shape corresponding to the upper heater is formed around the ice. 
     However, in a case of the present embodiment, by using a DC heater having a low output itself, it is possible to reduce the amount of heat transferred to the upper tray  150  and to prevent the formation of an opaque band around the ice. 
     The upper heater  148  may be disposed to surround the circumference of each of the plurality of upper chambers  152  so that the heat of the upper heater  148  is uniformly transferred to the plurality of upper chambers  152  of the upper tray  150 . 
     In addition, the upper heater  148  may contact the circumference of each of the chamber walls  153  respectively defining the plurality of upper chambers  152 . Here, the upper heater  148  may be disposed at a position that is lower than that of the inlet opening  154 . 
     Since the heater receiving groove  124   a  is recessed from the recessed portion  122 , the heater receiving groove  124   a  may be defined by an outer wall  124   b  and an inner wall  124   c.    
     The upper heater  148  may have a diameter greater than that of the heater receiving groove  124   a  so that the upper heater  148  protrudes to the outside of the heater coupling portion  124  in the state where the upper heater  148  is received in the heater receiving groove  124   a.    
     Since a portion of the upper heater  148  protrudes to the outside of the heater receiving groove  124   a  in the state where the upper heater  148  is received in the heater receiving groove  124   a,  the upper heater  148  may contact the upper tray  150 . 
     A separation prevention protrusion  124   d  may be provided on one of the outer wall  124   b  and the inner wall  124   c  to prevent the upper heater  148  received in the heater receiving groove  124   a  from being separated from the heater receiving groove  124   a.    
     In  FIG. 12 , for example, a plurality of separation prevention protrusions  124   d  are provided on the inner wall  124   c.    
     The separation prevention protrusion  124   d  may protrude from an end of the inner wall  124   c  toward the outer wall  124   b.    
     Here, a protruding length of the separation prevention protrusion  124   d  may be less than about ½ of a distance between the outer wall  124   b  and the inner wall  124   c  to prevent the upper heater  148  from being easily separated from the heater receiving groove  124   a  without interfering with the insertion of the upper heater  148  by the separation prevention protrusion  124   d.    
     As illustrated in  FIG. 13 , in the state where the upper heater  148  is received in the heater receiving groove  124   a,  the upper heater  148  may be divided into a rounded portion  148   c  and a linear portion  148   d.    
     In other words, the heater receiving groove  124   a  may include a rounded portion and a linear portion. Thus, the upper heater  148  may be divided into the rounded portion  148   c  and the linear portion  148   d  to correspond to the rounded portion and the linear portion of the heater receiving groove  124   a.    
     The rounded portion  148   c  may be a portion disposed along the circumference of the upper chamber  152  and also a portion that is bent to be rounded in a horizontal direction. 
     The liner portion  148   d  may be a portion connecting the rounded portions  148   c  corresponding to the upper chambers  152  to each other. 
     Since the heater  148  is disposed at a position lower than that of the inlet opening  154 , a line connecting two points of the upper rounded portions, which are spaced apart from each other, to each other may pass through upper chamber  152 . 
     Since the rounded portion  148   c  of the upper heater  148  may be separated from the heater receiving groove  124   a,  the separation prevention protrusion  124   d  may be disposed to contact the rounded portion  148   c.    
     A through-opening  124   e  may be defined in a bottom surface of the heater receiving groove  124   a.  When the upper heater  148  is received in the heater receiving groove  124   a,  a portion of the upper heater  148  may be disposed in the through-opening  124   e.  For example, the through-opening  124   e  may be defined in a portion of the upper heater  148  facing the separation prevention protrusion  124   d.    
     When the upper heater  148  is bent to be horizontally rounded, tension of the upper heater  148  may increase to cause disconnection, and also, the upper heater  148  may be separated from the heater receiving groove  124   a.    
     However, when the through-opening  124   e  is defined in the heater receiving groove  124   a  like this embodiment, a portion of the upper heater  148  may be disposed in the through-opening  124   e  to reduce the tension of the upper heater  148 , thereby preventing the heater receiving groove  124   a  from being separated from the upper heater  148 . 
     As illustrated in  FIG. 14 , in a state where a power input terminal  148   a  and a power output terminal  148   b  of the upper heater  148  are disposed in parallel to each other, the upper heater  148  may pass through a heater through-hole  125  defined in the upper case  120 . 
     Since the upper heater  148  is received from a lower side of the upper case  120 , the power input terminal  148   a  and the power output terminal  148   b  of the upper heater  148  may extend upward to pass through the heater through-hole  125 . 
     The power input terminal  148   a  and the power output terminal  148   b  passing through the heater through-hole  125  may be connected to one first connector  129   a.    
     In addition, a second connector  129   c  to which two wires  129   d  connected to correspond to the power input terminal  148   a  and the power output terminal  148   b  are connected may be connected to the first connector  129   a.    
     A first guide portion  126  guiding the upper heater  148 , the first connector  129   a,  the second connector  129   c,  and the wire  129   d  may be provided on the upper plate  121  of the upper case  120 . 
     In  FIG. 14 , for example, a structure in which the first guide portion  126  guides the first connector  129   a  is illustrated. 
     The first guide portion  126  may extend upward from the top surface of the upper plate  121  and have an upper end that is bent in the horizontal direction. 
     Thus, the upper bent portion of the first guide portion  126  may limit upward movement of the first connector  126 . 
     The electric wire  129   d  may be led out to the outside of the upper case  120  after being bent in an approximately “U” shape to prevent interference with the surrounding structure. 
     Since the electric wire  129   d  is bent at least once, the upper case  120  may further include electric wire guides  127  and  128  for fixing a position of the wire  129   d.    
     The electric wire guides  127  and  128  may include a first guide  127  and a second guide  128 , which are disposed to be spaced apart from each other in the horizontal direction. The first guide  127  and the second guide  128  may be bent in a direction corresponding to the bending direction of the wire  129   d  to minimize damage of the wire  129   d  to be bent. 
     In other words, each of the first guide  127  and the second guide  128  may include a curved portion. 
     To limit upward movement of the wire  129   d  disposed between the first guide  127  and the second guide  128 , at least one of the first guide  127  and the second guide  128  may include an upper guide  127   a  extending toward the other guide. 
       FIG. 15  is a sectional view illustrating a state where the upper assembly has been assembled. 
     Referring to  FIG. 15 , in the state where the upper heater  148  is coupled to the heater coupling portion  124  of the upper case  120 , the upper case  120 , the upper tray  150 , and the upper supporter  170  may be coupled to each other. 
     The first upper protrusion  165  of the upper tray  150  may be inserted into the first upper slot  131  of the upper case  120 . Also, the second upper protrusion  166  of the upper tray  150  may be inserted into the second upper slot  132  of the upper case  120 . 
     Then, the first lower protrusion  167  of the upper tray  150  may be inserted into the first lower slot  176  of the upper supporter  170 , and the second lower protrusion  168  of the upper tray  150  may be inserted into the second lower slot  177  of the upper supporter  170 . 
     Thus, the fastening boss  175  of the upper supporter  170  may pass through the through-hole of the upper tray  150  and then be received in the sleeve  133  of the upper case  120 . In this state, the bolt B 1  may be coupled to the fastening boss  175  from an upper side of the fastening boss  175 . 
     In the state where the bolt B 1  is coupled to the fastening boss  175 , the head portion of the bolt B 1  may be disposed at a position higher than that of the upper plate  121 . 
     On the other hand, since the hinge supporters  135  and  136  are disposed lower than the upper plate  121 , while the lower assembly  200  rotates, the upper assembly  110  or the connection unit  350  may be prevented from interfering with the head portion of the bolt B 1 . 
     While the upper assembly  110  is assembled, a plurality of unit guides  181  and  182  of the upper supporter  170  may protrude upward from the upper plate  121  through the through-opening (see reference numerals  139   a  and  139   b  of  FIG. 5 ) defined in both sides of the upper plate  121 . 
     As described above, the upper ejector  300  passes through the guide slots  183  of the unit guides  181  and  182  protruding upward from the upper plate  121 . 
     Thus, the upper ejector  300  may descend in the state of being disposed above the upper plate  121  and be inserted into the upper chamber  152  to separate ice of the upper chamber  152  from the upper tray  150 . 
     When the upper assembly  110  is assembled, the heater coupling portion  124  to which the upper heater  148  is coupled may be received in the first receiving portion  160  of the upper tray  150 . 
     In the state where the heater coupling portion  124  is received in the first receiving portion  160 , the upper heater  148  may contact the bottom surface  160   a  of the first receiving portion  160 . 
     Like this embodiment, when the upper heater  148  is received in the heater coupling portion  124  having the recessed shape to contact the upper tray body  151 , heat of the upper heater  148  may be minimally transferred to other portion except for the upper tray body  151 . 
     At least a portion of the upper heater  148  may be disposed to vertically overlap the upper chamber  152  so that the heat of the upper heater  148  is smoothly transferred to the upper chamber  152 . 
     In this embodiment, the rounded portion  148   c  of the upper heater  148  may vertically overlap the upper chamber  152 . 
     In other words, a maximum distance between two points of the rounded portion  148   c,  which are disposed at opposite sides with respect to the upper chamber  152  may be less than a diameter of the upper chamber  152 . 
     &lt;Lower Case&gt; 
       FIG. 16  is a perspective view illustrating the lower assembly according to an embodiment of the present disclosure,  FIG. 17  is a top perspective view illustrating a lower case according to one embodiment of the present disclosure, and  FIG. 18  is a bottom perspective view illustrating a lower case according to one embodiment of the present disclosure. 
     Referring to  FIGS. 16 to 18 , the lower assembly  200  may include a lower tray  250 , a lower supporter  270 , and a lower case  210 . 
     The lower case  210  may surround the circumference of the lower tray  250 , and the lower supporter  270  may support the lower tray  250 . 
     In addition, the connection unit  350  may be coupled to the lower supporter  270 . 
     The connection unit  350  may include a first link  352  that receives power of the driving unit  180  to allow the lower supporter  270  to rotate and a second link  356  connected to the lower supporter  270  to transmit rotation force of the lower supporter  270  to the upper ejector  300  when the lower supporter  270  rotates. 
     In addition, the first link  352  and the lower supporter  270  may be connected to each other by an elastic member  360 . For example, the elastic member  360  may be a coil spring. As another example, the elastic member  360  may be a tension spring. 
     The elastic member  360  may have one end connected to the first link  362  and the other end connected to the lower supporter  270 . 
     The elastic member  360  provides elastic force to the lower supporter  270  so that contact between the upper tray  150  and the lower tray  250  is maintained. 
     In this embodiment, the first link  352  and the second link  356  may be disposed on both sides of the lower supporter  270 , respectively. 
     In addition, one of the two first links may be connected to the driving unit  180  to receive the rotation force from the driving unit  180 . 
     The two first links  352  may be connected to each other by a connection shaft (see reference numeral  370  of  FIG. 4 ). 
     A hole  358  through which the upper ejector body  310  of the upper ejector  300  passes may be defined in an upper end of the second link  356 . 
     In detail, a separation prevention hole  358  through which the separation prevention protrusion  312  penetrates is formed at an upper end portion of the second link  356 . 
     The separation prevention hole  358  may be formed with a circular central portion  358   a  so as to correspond to the separation prevention protrusion  312  and a pair of groove portions  356   b  formed so as to be recessed in the radial direction toward the outside from both sides of the central portion  358   a  so as to communicate with the central portion  358   a.    
     Therefore, the separation prevention hole  358  can be inserted into the separation prevention projection  312  in a method in which the central portion  312   a  and the projection portion  312   b  of the separation prevention protrusion  312  are into the central portion  358   a  and the groove portion  358   b  of the separation prevention hole  358 . In addition, in a state where the separation prevention protrusion  312  is inserted into the separation prevention hole  358 , while the groove portion  358   b  and the protrusion portion  312   b  are shifted, the separation prevention protrusion  312  can be not separated from the separation prevention hole  358  and maintain a state of being inserted. 
     The lower case  210  may include a lower plate  211  for fixing the lower tray  250 . 
     A portion of the lower tray  250  may be fixed to contact a bottom surface of the lower plate  211 . 
     An opening  212  through which a portion of the lower tray  250  passes may be defined in the lower plate  211 . 
     For example, when the lower tray  250  is fixed to the lower plate  211  in a state where the lower tray  250  is disposed below the lower plate  211 , a portion of the lower tray  250  may protrude upward from the lower plate  211  through the opening  212 . 
     The lower case  210  may further include a circumferential wall  214  (or a cover wall) surrounding the lower tray  250  passing through the lower plate  211 . 
     The circumferential wall  214  may include a vertical wall  214   a  and a curved wall  215 . 
     The vertical wall  214   a  is a wall vertically extending upward from the lower plate  211 . The curved wall  215  is a wall that is rounded in a direction that is away from the opening  212  upward from the lower plate  211 . 
     The vertical wall  214   a  may include a first coupling slit  214   b  coupled to the lower tray  250 . The first coupling slit  214   b  may be defined by recessing an upper end of the vertical wall downward. 
     The curved wall  215  may include a second coupling slit  215   a  to couple to the lower tray  250 . 
     The second coupling slit  215   a  may be defined by recessing an upper end of the curved wall  215  downward. 
     The lower case  210  may further include a first fastening boss  216  and a second fastening boss  217 . 
     The first fastening boss  216  may protrude downward from the bottom surface of the lower plate  211 . For example, the plurality of first fastening bosses  216  may protrude downward from the lower plate  211 . 
     The plurality of first fastening bosses  216  may be arranged to be spaced apart from each other in the direction of the arrow A with respect to  FIG. 17 . 
     The second fastening boss  217  may protrude downward from the bottom surface of the lower plate  211 . For example, the plurality of second fastening bosses  217  may protrude from the lower plate  211 . The plurality of first fastening bosses  217  may be arranged to be spaced apart from each other in the direction of the arrow A with respect to  FIG. 17 . 
     The first fastening boss  216  and the second fastening boss  217  may be disposed to be spaced apart from each other in the direction of the arrow B. 
     In this embodiment, a length of the first fastening boss  216  and a length of the second fastening boss  217  may be different from each other. For example, the first fastening boss  216  may have a length less than that of the second fastening boss  217 . 
     The first fastening member may be coupled to the first fastening boss  216  at an upper portion of the first fastening boss  216 . On the other hand, the second fastening member may be coupled to the second fastening boss  217  at a lower portion of the second fastening boss  217 . 
     A groove  215   b  for movement of the fastening member may be defined in the curved wall  215  to prevent the first fastening member from interfering with the curved wall  215  while the first fastening member is coupled to the first fastening boss  216 . 
     The lower case  210  may further include a slot  218  coupled to the lower tray  250 . 
     A portion of the lower tray  250  may be inserted into the slot  218 . The slot  218  may be disposed adjacent to the vertical wall  214   a.    
     For example, a plurality of slots  218  may be defined to be spaced apart from each other in the direction of the arrow A of  FIG. 17 . Each of the slots  218  may have a curved shape. 
     The lower case  210  may further include an receiving groove  218   a  into which a portion of the lower tray  250  is inserted. The receiving groove  218   a  may be defined by recessing a portion of the lower tray  211  toward the curved wall  215 . 
     The lower case  210  may further include an extension wall  219  contacting a portion of the circumference of the side surface of the lower plate  212  in the state of being coupled to the lower tray  250 . The extension wall  219  may linearly extend in the direction of the arrow A. 
     &lt;Lower Tray&gt; 
       FIG. 19  is a top perspective view illustrating a lower tray according to an embodiment of the present disclosure,  FIGS. 20 and 21  are bottom perspective views illustrating a lower tray according to an embodiment of the present disclosure, and  FIG. 22  is a side view illustrating a lower tray according to one embodiment of the present disclosure. 
     Referring to  FIGS. 19 to 22 , the lower tray  250  may be made of a flexible material that is capable of being restored to its original shape after being deformed by an external force. 
     For example, the lower tray  250  may be made of a silicone material. Like this embodiment, when the lower tray  250  is made of a silicone material, the lower tray  250  may be restored to its original shape even through external force is applied to deform the lower tray  250  during the ice-separation process. Thus, in spite of repetitive ice-making, spherical ice may be made. 
     If the lower tray  250  is made of a metal material, when the external force is applied to the lower tray  250  to deform the lower tray  250  itself, the lower tray  250  may not be restored to its original shape any more. 
     In this case, after the lower tray  250  is deformed in shape, the spherical ice may not be made. In other words, it is impossible to repeatedly make the spherical ice. 
     On the other hand, like this embodiment, when the lower tray  250  is made of the flexible material that is capable of being restored to its original shape, this limitation may be solved. 
     Also, when the lower tray  250  is made of the silicone material, the lower tray  250  may be prevented from being melted or thermally deformed by heat provided from an upper heater that will be described later. 
     The lower tray  250  may include a lower tray body  251  defining a lower chamber  252  that is a portion of the ice chamber  111 . 
     The lower tray body  251  may define a plurality of lower chambers  252 . 
     For example, the plurality of lower chambers  252  may include a first lower chamber  252   a,  a second lower chamber  252   b,  and a third lower chamber  252   c.    
     The lower tray body  251  may include three chamber walls  252   d  defining three independent lower chambers  252   a,    252   b,  and  252   c.  The three chamber walls  252   d  may be integrated in one body to form the lower tray body  251 . 
     The first lower chamber  252   a,  the second lower chamber  252   b,  and the third lower chamber  252   c  may be arranged in a line. For example, the first lower chamber  252   a,  the second lower chamber  252   b,  and the third lower chamber  252   c  may be arranged in a direction of an arrow A with respect to  FIG. 19 . 
     The lower chamber  252  may have a hemispherical shape or a shape similar to the hemispherical shape. In other words, a lower portion of the spherical ice may be made by the lower chamber  252 . 
     In the present specification, the shape similar to hemisphere means a shape that is not a perfect hemisphere but is close to the hemisphere. 
     The lower tray  250  may further include a first extension portion  253  horizontally extending from an edge of an upper end of the lower tray body  251 . The first extension portion  253  may be continuously formed along the circumference of the lower tray body  251 . 
     The lower tray  250  may further include a circumferential wall  260  extending upward from an upper surface of the first extension portion  253 . 
     The lower surface of the upper tray body  151  may be in contact with the upper surface  251   e  of the lower tray body  251 . 
     The circumferential wall  260  may surround the upper tray body  251  seated on the top surface  251   e  of the lower tray body  251 . 
     The circumferential wall  260  may include a first wall  260   a  surrounding the vertical wall  153   a  of the upper tray body  151  and a second wall  260   b  surrounding the curved wall  153   b  of the upper tray body  151 . 
     The first wall  260   a  is a vertical wall vertically extending from the top surface of the first extension portion  253 . The second wall  260   b  is a curved wall having a shape corresponding to that of the upper tray body  151 . In other words, the second wall  260   b  may be rounded upward from the first extension portion  253  in a direction that is away from the lower chamber  252 . 
     The lower tray  250  may further include a second extension portion  254  horizontally extending from the circumferential wall  250 . 
     The second extension portion  254  may be disposed higher than the first extension portion  253 . Thus, the first extension portion  253  and the second extension portion  254  may be stepped with respect to each other. 
     The second extension portion  254  may include a first upper protrusion  255  inserted into the slot  218  of the lower case  210 . The first upper protrusion  255  may be disposed to be horizontally spaced apart from the circumferential wall  260 . 
     For example, the first upper protrusion  255  may protrude upward from a top surface of the second extension portion  254  at a position adjacent to the first wall  260   a.    
     Although not limited, a plurality of first upper protrusions  255  may be arranged to be spaced apart from each other in the direction of the arrow A with respect to  FIG. 19 . The first upper protrusion  255  may extend, for example, in a curved shape. 
     The second extension portion  254  may include a first lower protrusion  257  inserted into a protrusion groove of the lower case  270 , which will be described later. The first lower protrusion  257  may protrude downward from a bottom surface of the second extension portion  254 . 
     Although not limited, the plurality of first lower protrusions  257  may be arranged to be spaced apart from each other in the direction of arrow A. 
     The first upper protrusion  255  and the first lower protrusion  257  may be disposed at opposite sides with respect to a vertical direction of the second extension portion  254 . At least a portion of the first upper protrusion  255  may vertically overlap the second lower protrusion  257 . 
     A plurality of through-holes may be defined in the second extension portion  254 . 
     The plurality of through-holes  256  may include a first through-hole  256   a  through which the first fastening boss  216  of the lower case  210  passes and a second through-hole  256   b  through which the second fastening boss  217  of the lower case  210  passes. 
     For example, the plurality of through-holes  256   a  may be defined to be spaced apart from each other in the direction of the arrow A of  FIG. 19 . 
     Also, the plurality of second through-holes  256   b  may be disposed to be spaced apart from each other in the direction of the arrow A of  FIG. 19 . 
     The plurality of first through-holes  256   a  and the plurality of second through-holes  256   b  may be disposed at opposite sides with respect to the lower chamber  252 . 
     A portion of the plurality of second through-holes  256   b  may be defined between the two first upper protrusions  255 . Also, a portion of the plurality of second through-holes  256   b  may be defined between the two first lower protrusions  257 . 
     The second extension portion  254  may further a second upper protrusion  258 . The second upper protrusion  258  may be disposed at an opposite side of the first upper protrusion  255  with respect to the lower chamber  252 . 
     The second upper protrusion  258  may be disposed to be horizontally spaced apart from the circumferential wall  260 . For example, the second upper protrusion  258  may protrude upward from a top surface of the second extension portion  254  at a position adjacent to the second wall  260   b.    
     Although not limited, the plurality of second upper protrusions  258  may be arranged to be spaced apart from each other in the direction of the arrow A of  FIG. 19 . 
     The second upper protrusion  258  may be received in the receiving groove  218   a  of the lower case  210 . In the state where the second upper protrusion  258  is received in the receiving groove  218   a,  the second upper protrusion  258  may contact the curved wall  215  of the lower case  210 . 
     The circumferential wall  260  of the lower tray  250  may include a first coupling protrusion  262  coupled to the lower case  210 . 
     The first coupling protrusion  262  may horizontally protrude from the first wall  260   a  of the circumferential wall  260 . The first coupling protrusion  262  may be disposed on an upper portion of a side surface of the first wall  260   a.    
     The first coupling protrusion  262  may include a neck portion  262   a  having a relatively less diameter when compared to those of other portions. The neck portion  262   a  may be inserted into a first coupling slit  214   b  defined in the circumferential wall  214  of the lower case  210 . 
     The circumferential wall  260  of the lower tray  250  may further include a second coupling protrusion  262   c  coupled to the lower case  210 . 
     The second coupling protrusion  262   c  may horizontally protrude from the second wall  260   a  of the circumferential wall  260 . The second coupling protrusion  260   c  may be inserted into a second coupling slit  215   a  defined in the circumferential wall  214  of the lower case  210 . 
     The second extension portion  254  may include a second lower protrusion  266 . The second lower protrusion  266  may be disposed at an opposite side of the second lower protrusion  257  with respect to the lower chamber  252 . 
     The second lower protrusion  266  may protrude downward from a bottom surface of the second extension portion  254 . For example, the second lower protrusion  266  may linearly extend. 
     A portion of the plurality of first through-holes  256   a  may be defined between the second lower protrusion  266  and the lower chamber  252 . 
     The second lower protrusion  266  may be received in a guide groove defined in the lower supporter  270 , which will be described later. 
     The second extension portion  254  may further a side restriction portion  264 . The side restriction portion  264  restricts horizontal movement of the lower tray  250  in the state where the lower tray  250  is coupled to the lower case  210  and the lower supporter  270 . 
     The side restriction portion  264  laterally protrudes from the second extension portion  254  and has a vertical length greater than a thickness of the second extension portion  254 . For example, one portion of the side restriction portion  264  may be disposed higher than the top surface of the second extension portion  254 , and the other portion of the side restriction portion  264  may be disposed lower than the bottom surface of the second extension portion  254 . 
     Thus, the one portion of the side restriction portion  264  may contact a side surface of the lower case  210 , and the other portion may contact a side surface of the lower supporter  270 . 
     &lt;Lower Supporter&gt; 
       FIG. 23  is a top perspective view illustrating a lower supporter according to one embodiment of the present disclosure,  FIG. 24  is a bottom perspective view illustrating the lower supporter according to an embodiment of the present disclosure, and  FIG. 25  is a sectional view illustrating a state where the lower assembly is assembled. 
     Referring to  FIGS. 23 to 25 , the lower supporter  270  may cover more than half of the lower chamber  272  so that the shape of the lower chamber  272  may be maintained in the ice-making process. 
     The supporter body  271  may include three chamber receiving portions  272  accommodating the three chamber walls  252   d  of the lower tray  250 . The chamber receiving portion  272  may have a hemispherical shape. 
     The supporter body  271  may have a lower opening  274  through which the lower ejector  400  passes during the ice-separation process. For example, three lower openings  274  may be defined to correspond to the three chamber receiving portions  272  in the supporter body  271 . 
     A reinforcement rib  275  reinforcing strength may be disposed along a circumference of the lower opening  274 . 
     Also, the adjacent two chamber walls  252   d  of the three chamber walls  252   d  may be connected to each other by a connection rib  273 . The connection rib  273  may reinforce strength of chamber walls  252   d.    
     The lower supporter  270  may further include a first extension wall  285  horizontally extending from an upper end of the supporter body  271 . 
     The lower supporter  270  may further include a second extension wall  286  that is formed to be stepped with respect to the first extension wall  285  on an edge of the first extension wall  285 . 
     A top surface of the second extension wall  286  may be disposed higher than the first extension wall  285 . 
     The first extension portion  253  of the lower tray  250  may be seated on a top surface  271   a  of the supporter body  271 , and the second extension portion  285  may surround side surface of the first extension portion  253  of the lower tray  250 . Here, the second extension wall  286  may contact the side surface of the first extension portion  253  of the lower tray  250 . 
     The lower supporter  270  may further include a first protrusion groove  287  accommodating the first lower protrusion  257  of the lower tray  250 . 
     The first protrusion groove  287  may extend in a curved shape. The first protrusion groove  287  may be defined, for example, in a second extension wall  286 . 
     The lower supporter  270  may further include a first fastening groove  286   a  to which a first fastening member B 2  passing through the first fastening boss  216  of the upper case  210  is coupled. 
     The first fastening groove  286   a  may be provided, for example, in the second extension wall  286 . 
     The plurality of first coupling grooves  286   a  may be disposed to be spaced apart from each other in the direction of the arrow A in the second extension wall  286 . A portion of the plurality of first coupling grooves  286   a  may be positioned between the adjacent two first protrusion grooves  287 . 
     The lower supporter  270  may further include a boss through-hole  286   b  through which the second fastening boss  217  of the upper case  210  passes. 
     The boss through-hole  286   b  may be provided, for example, in the second extension wall  286 . A sleeve  286   c  surrounding the second fastening boss  217  passing through the boss through-hole  286   b  may be disposed on the second extension wall  286 . The sleeve  286   c  may have a cylindrical shape with an opened lower portion. 
     The first fastening member B 2  may be fastened to the first fastening groove  286   a  after passing through the first fastening boss  216  from an upper side of the lower case  210 . 
     The second fastening member B 3  may be fastened to the second fastening boss  217  from a lower side of the lower supporter  270 . 
     The sleeve  286   c  may have a lower end that is disposed at the same height as a lower end of the second fastening boss  217  or disposed at a height lower than that of the lower end of the second fastening boss  217 . 
     Thus, while the second fastening member B 3  is coupled, the head portion of the second fastening member B 3  may contact bottom surfaces of the second fastening boss  217  and the sleeve  286   c  or may contact a bottom surface of the sleeve  286   c.    
     The lower supporter  270  may further include an outer wall  280  disposed to surround the lower tray body  251  in a state of being spaced outward from the outside of the lower tray body  251 . 
     The outer wall  280  may, for example, extend downward along an edge of the second extension wall  286 . 
     The lower supporter  270  may further include a plurality of hinge bodies  281  and  282  respectively connected to hinge supporters  135  and  136  of the upper case  210 . 
     The plurality of hinge bodies  281  and  282  may be disposed to be spaced apart from each other in a direction of an arrow A of  FIG. 23 . Each of the hinge bodies  281  and  282  may further include a second hinge hole  281   a.    
     The shaft connection portion  353  of the first link  352  may pass through the second hinge hole  281 . The connection shaft  370  may be connected to the shaft connection portion  353 . 
     In addition, the shaft connection portion  353  may be provided with a groove of the polygon on the opposite surface, and the shaft connection portion  353  may be connected by a connection shaft  370  having a polygonal cross-section in which both ends thereof are inserted into the groove. 
     For example, the shaft connection portion  353  has a groove having a square cross-section on the opposite surface, and the cross-section of the connection shaft  370  may have a square cross-section. 
     In addition, the first link  352  may be formed so that the shaft coupling portion  352   a  connected to the rotation shaft of the drive unit  180  protrudes on the surface facing the drive unit  180 . 
     The shaft coupling portion  352   a  may form a hollow. In addition, a plurality of reinforcing ribs may be formed around the shaft coupling portion  352   a.    
     Therefore, when the drive unit  180  rotates, while the shaft coupling portion  352   a  rotates, the first link  352  rotates. At this time, the first links  352  on both sides may rotate at the same time by the connection shaft  370 . 
     A distance between the plurality of hinge bodies  281  and  282  may be less than that between the plurality of hinge supporters  135  and  136 . Thus, the plurality of hinge bodies  281  and  282  may be disposed between the plurality of hinge supporters  135  and  136 . 
     The lower supporter  270  may further include a coupling shaft  283  to which the second link  356  is rotatably coupled. The coupling shaft  283  may be disposed on each of both surfaces of the outer wall  280 . 
     In addition, the lower supporter  270  may further include an elastic member coupling portion  284  to which the elastic member  360  is coupled. The elastic member coupling portion  284  may define a space  284   b  in which a portion of the elastic member  360  is received. Since the elastic member  360  is received in the elastic member coupling portion  284  to prevent the elastic member  360  from interfering with the surrounding structure. 
     In addition, the elastic member coupling portion  284  may include a hook portion  284   a  on which a lower end of the elastic member  370  is hooked. 
     &lt;Coupling Structure of Lower Heater&gt; 
       FIG. 26  is a plan view illustrating a lower supporter according to one embodiment of the present disclosure,  FIG. 27  is a perspective view illustrating a state where a lower heater is coupled to a lower supporter of  FIG. 26 , and  FIG. 28  is a view illustrating a state where a lower assembly is coupled to an upper assembly and, at the same time, an electric wire connected to a lower heater penetrates an upper case. 
     Referring to  FIGS. 26 to 28 , the ice maker  100  according to this embodiment may further include a lower heater  296  for applying heat to the lower tray  250  during the ice-making process. 
     The lower heater  297  may provide the heat to the lower chamber  252  during the ice-making process so that ice within the ice chamber  111  is frozen from an upper side. 
     Also, since lower heater  296  generates heat in the ice-making process, bubbles within the ice chamber  111  may move downward during the ice-making process. When the ice is completely made, a remaining portion of the spherical ice except for the lowermost portion of the ice may be transparent. According to this embodiment, the spherical ice that is substantially transparent may be made. 
     For example, the lower heater  296  may be a wire-type heater. 
     The lower heater  296  may be installed on the lower supporter  270 . Also, the lower heater  296  may contact the lower tray  250  to provide heat to the lower chamber  252 . 
     For example, the lower heater  296  may contact the lower tray body  251 . Also, the lower heater  296  may be disposed to surround the three chamber walls  252   d  of the lower tray body  251 . 
     The lower supporter  270  may further include a heater coupling portion  290  to which the lower heater  296  is coupled. 
     The heater coupling portion  290  may include a heater receiving groove  291  that is recessed downward from the chamber receiving portion  272  of the lower tray body  251 . 
     Since the heater receiving groove  291  is recessed, the heater coupling portion  290  may include an inner wall  291   a  and an outer wall  291   b.    
     The inner wall  291   a  may have, for example, a ring shape, and the outer wall  291   b  may be disposed to surround the inner wall  291   a.    
     When the lower heater  296  is received in the heater receiving groove  291 , the lower heater  296  may surround at least a portion of the inner wall  291   a.    
     The lower opening  274  may be defined in a region defined by the inner wall  291   a.  Thus, when the chamber wall  252   d  of the lower tray  250  is received in the chamber receiving portion  272 , the chamber wall  252   d  may contact a top surface of the inner wall  291   a.  The top surface of the inner wall  291   a  may be a rounded surface corresponding to the chamber wall  252   d  having the hemispherical shape. 
     The lower heater may have a diameter greater than a recessed depth of the heater receiving groove  291  so that a portion of the lower heater  296  protrudes to the outside of the heater receiving groove  291  in the state where the lower heater  296  is received in the heater receiving groove  291 . 
     A separation prevention protrusion  291   c  may be provided on one of the outer wall  291   b  and the inner wall  291   a  to prevent the lower heater  296  received in the heater receiving groove  291  from being separated from the heater receiving groove  291 . 
     In  FIG. 26 , the separation prevention protrusions  291   c  is provided on the inner wall  291   a.    
     Since the inner wall  291   a  has a diameter less than that of the chamber receiving portion  272 , the lower heater  196  may move along a surface of the chamber receiving portion  272  and then be received in the heater receiving groove  291  in a process of assembling the lower heater  196 . 
     In other words, the lower heater  196  is received in the heater receiving groove  291  from an upper side of the outer wall  291   a  toward the inner wall  291   a.  Thus, the separation prevention protrusion  291   c  may be disposed on the inner wall  291   a  to prevent the lower heater  196  from interfering with the separation prevention protrusion  291   c  while the lower heater  196  is received in the heater receiving groove  291 . 
     The separation prevention protrusion  291   c  may protrude from an upper end of the inner wall  291   a  toward the outer wall  291   b.    
     A protruding length of the separation prevention protrusion  291   c  may be about ½ of a distance between the outer wall  291   b  and the inner wall  291   a.    
     As illustrated in  FIG. 27 , in the state where the lower heater  296  is received in the heater receiving groove  291 , the lower heater  296  may be divided into a lower rounded portion  296   a  and a linear portion  296   b.    
     The rounded portion  296   a  may be a portion disposed along the circumference of the lower chamber  252  and also a portion that is bent to be rounded in a horizontal direction. 
     The liner portion  296   b  may be a portion connecting the rounded portions  296   a  corresponding to the lower chambers  252  to each other. 
     Since the rounded portion  296   a  of the lower heater  296  may be separated from the heater receiving groove  291 , the separation prevention protrusion  291   c  may be disposed to contact the rounded portion  296   a.    
     A through-opening  291   d  may be defined in a bottom surface of the heater receiving groove  291 . When the lower heater  296  is received in the heater receiving groove  291 , a portion of the upper heater  296  may be disposed in the through-opening  291   d.  For example, the through-opening  291   d  may be defined in a portion of the lower heater  296  facing the separation prevention protrusion  291   c.    
     When the lower heater  296  is bent to be horizontally rounded, tension of the lower heater  296  may increase to cause disconnection, and also, the lower heater  296  may be separated from the heater receiving groove  291 . 
     However, when the through-opening  291   d  is defined in the heater receiving groove  291  like this embodiment, a portion of the lower heater  296  may be disposed in the through-opening  291   d  to reduce the tension of the lower heater  296 , thereby preventing the heater receiving groove  291  from being separated from the lower heater  296 . 
     The lower supporter  270  may include a first guide groove  293  guiding a power input terminal  296   c  and a power output terminal of the lower heater  296  received in the heater receiving groove  291  and a second guide groove  294  extending in a direction crossing the first guide groove  293 . 
     For example, the first guide groove  293  may extend in a direction of an arrow B in the heater receiving portion  291 . 
     In addition, the second guide groove  294  may extend from an end of the first guide groove  293  in a direction of an arrow A. In this embodiment, the direction of the arrow A may be a direction that is parallel to the extension direction of a rotational central axis C 1  of the lower assembly. 
     Referring to  FIG. 27 , the first guide groove  293  may extend from one of the left and right chamber receiving portions except for the intermediate chamber receiving portion of the three chamber receiving portions. 
     For example, in  FIG. 27 , the first guide groove  293  extends from the chamber receiving portion, which is disposed at the left side, of the three chamber receiving portions. 
     As illustrated in  FIG. 27 , in a state where the power input terminal  296   c  and the power output terminal  296   d  of the lower heater  296  are disposed in parallel to each other, the lower heater  296  may be received in the first guide groove  293 . 
     The power output terminal  296   c  and the power output terminal  296   d  of the lower heater  296  may be connected to one first connector  297   a.    
     In addition, a second connector  297   b  to which two wires  298  connected to correspond to the power input terminal  296   a  and the power output terminal  296   b  are connected may be connected to the first connector  297   a.    
     In this embodiment, in the state where the first connector  297   a  and the second connector  297   b  are connected to each other, the first connector  297   a  and the second connector  297   b  are received in the second guide groove  294 . 
     In addition, the electric wire  298  connected to the second connector  297   b  is led out from the end of the second guide groove  294  to the outside of the lower supporter  270  through an lead-out slot  295  defined in the lower supporter  270 . 
     According to this embodiment, since the first connector  297   a  and the second connector  297   b  are received in the second guide groove  294 , the first connector  297   a  and the second connector  297   b  are not exposed to the outside when the lower assembly  200  is completely assembled. 
     As described above, the first connector  297   a  and the second connector  297   b  may not be exposed to the outside to prevent the first connector  297   a  and the second connector  297   b  from interfering with the surrounding structure while the lower assembly  200  rotates and prevent the first connector  297   a  and the second connector  297   b  from being separated. 
     In addition, since the first connector  297   a  and the second connector  297   b  are received in the second guide groove  294 , one portion of the electric wire  298  may be disposed in the second guide groove  294 , and the other portion may be disposed outside the lower supporter  270  by the lead-out slot  295 . 
     Here, since the second guide groove  294  extends in a direction parallel to the rotational central axis C 1  of the lower assembly  200 , one portion of the electric wire  298  may extend in the direction parallel to the rotational central axis C 1 . 
     The other portion of the electric wire  298  may extend from the outside of the lower supporter  270  in a direction crossing the rotational central axis C 1 . 
     According to the arrangement of the electric wires  298 , tensile force may not merely act on the wires  298 , but torsion force may act on the electric wires  298  during the rotation of the lower assembly  200 . 
     When compared that the tensile force acts on the electric wire  298 , if the torsion acts on the electric wire  298 , possibility of disconnection of the electric wire  298  may be very little. 
     According to this embodiment, while the lower assembly  200  rotates, the lower heater  296  may be maintained at a fixed position, and twisting force may act on the electric wire  298  to prevent the lower heater  296  from being damaged and disconnected. 
     The power input terminal  296   c  and the power output terminal  296   d  of the lower heater  296  are disposed in the first guide groove  293 . Here, since heat is also generated in the power input terminal  296   c  and the power output terminal  296   d,  heat provided to the left chamber receiving portion to which the first guide groove  293  extends may be greater than that provided to other chamber receiving portions. 
     In this case, if magnitude of the heat provided to each chamber receiving portion is different, transparency of the made spherical ice after the ice-making process and the ice-separation process may be changed for each ice. 
     Thus, a detour receiving groove  292  may be further provided in the chamber receiving portion (for example, the right chamber receiving portion), which is disposed farthest from the first guide groove  292 , of the three chamber receiving portions to minimize a difference in transparency for each ice. 
     For example, the detour receiving groove  292  may extend outward from the heater receiving groove  291  and then be bent so as to be disposed in a shape that is connected to the heater receiving groove  291 . 
     When a portion  296   e  of the lower heater  291  is additionally received in the detour receiving groove  292 , a contact area between the chamber wall received in the right chamber receiving portion  272  and the lower heater  296  may increase. 
     Thus, a protrusion  292   a  for fixing a position of the lower heater received in the detour receiving groove  292  may be additionally provided in the right chamber receiving portion  272 . 
     Referring to  FIG. 28 , in the state where the lower assembly  200  is coupled to the upper case  120  of the upper assembly  110 , the wire  298  led out to the outside of the lower supporter  270  may pass through a wire through-slot  138  defined in the upper case  120  to extend upward from the upper case  120 . 
     A restriction guide  139  for restricting the movement of the electric wire  298  passing through the electric wire through-slot  138  may be provided in the electric wire through-slot  138 . The restriction guide  139  may have a shape that is bent several times, and the electric wire  298  may be disposed in a region defined by the restriction guide  139 . 
       FIG. 29  is a cross-sectional view taken along line A-A of  FIG. 3A , and  FIG. 30  is a view illustrating a state where ice generation is completed in  FIG. 29 . 
     In  FIG. 29 , a state where the upper tray and the lower tray contact each other is illustrated. 
     Firstly, referring to  FIG. 29 , the upper tray  150  and the lower tray  250  vertically contact each other to complete the ice chamber  111 . 
     The bottom surface  151   a  of the upper tray body  151  contacts the top surface  251   e  of the lower tray body  251 . 
     Here, in the state where the top surface  251   e  of the lower tray body  251  contacts the bottom surface  151   a  of the upper tray body  151 , the elastic force of the elastic member  360  is applied to the lower supporter  270 . 
     The elastic force of the elastic member  360  may be applied to the lower tray  250  by the lower supporter  270 , and thus, the top surface  251   e  of the lower tray body  251  may press the bottom surface  151   a  of the upper tray body  151 . 
     Thus, in the state where the top surface  251   e  of the lower tray body  251  contacts the bottom surface  151   a  of the upper tray body  151 , the surfaces may be pressed with respect to each other to improve the adhesion. 
     As described above, when the adhesion between the top surface  251   e  of the lower tray body  251  and the bottom surface  151   a  of the upper tray increases, a gap between the two surfaces may not occur to prevent ice having a thin band shape along a circumference of the spherical ice from being made after the ice-making is completed. 
     The first extension portion  253  of the lower tray  250  is seated on the top surface  271   a  of the supporter body  271  of the lower supporter  270 . In addition, the second extension wall  286  of the lower supporter  270  contacts a side surface of the first extension portion  253  of the lower tray  250 . 
     The second extension portion  254  of the lower tray  250  may be seated on the second extension wall  286  of the lower supporter  270 . 
     In the state where the bottom surface  151   a  of the upper tray body  151  is seated on the top surface  251   e  of the lower tray body  251 , the upper tray body  151  may be received in an inner space of the circumferential wall  260  of the lower tray  250 . 
     Here, the vertical wall  153   a  of the upper tray body  151  may be disposed to face the vertical wall  260   a  of the lower tray  250 , and the curved wall  153   b  of the upper tray body  151  may be disposed to face the curved wall  260   b  of the lower tray  250 . 
     An outer face of the chamber wall  153  of the upper tray body  151  is spaced apart from an inner face of the circumferential wall  260  of the lower tray  250 . In other words, a space may be defined between the outer face of the chamber wall  153  of the upper tray body  151  and the inner face of the circumferential wall  260  of the lower tray  250 . 
     Water supplied through the water supply portion  180  is received in the ice chamber  111 . When a relatively large amount of water than a volume of the ice chamber  111  is supplied, water that is not received in the ice chamber  111  may flow into the space between the outer face of the chamber wall  153  of the upper tray body  151  and the inner face of the circumferential wall  260  of the lower tray  250 . 
     Thus, according to this embodiment, even though a relatively large amount of water than the volume of the ice chamber  111  is supplied, the water may be prevented from overflowing from the ice maker  100 . 
     Meanwhile, a heater contact portion  251   a  for allowing the contact area with the lower heater  296  to increase may be further provided on the lower tray body  251 . 
     The heater contact portion  251   a  may protrude from the bottom face of the lower tray body  251 . For example, the heater contact portion  251   a  may be formed in a ring shape on a lower surface of the lower tray body  251 . In addition, the bottom surface of the heater contact portion  251   a  may be a flat surface. 
     The lower tray body  251  may further include a convex portion  251   b  in which a portion of the lower portion of the lower tray body  251  is convex upward. In other words, the convex portion  251   b  may be disposed to be convex toward the inside of the ice chamber  111 . 
     A recessed portion  251   c  may be defined below the convex portion  251   b  so that the convex portion  251   b  has substantially the same thickness as the other portion of the lower tray body  251 . 
     In this specification, the “substantially the same” is a concept that includes completely the same shape and a shape that is not similar but there is little difference. 
     The convex portion  251   b  may be disposed to vertically face the lower opening  274  of the lower supporter  270 . 
     In addition, the lower opening  274  may be defined just below the lower chamber  252 . In other words, the lower opening  274  may be defined just below the convex portion  251   b.    
     The convex portion  251   b  may have a diameter D 1  less than that D 2  of the lower opening  274 . 
     When cold air is supplied to the ice chamber  111  in the state where the water is supplied to the ice chamber  111 , the liquid water is phase-changed into solid ice. Here, the water may be expanded while the water is changed in phase. The expansive force of the water may be transmitted to each of the upper tray body  151  and the lower tray body  251 . 
     In a case of this embodiment, although other portions of the lower tray body  251  are surrounded by the supporter body  271 , a portion (hereinafter, referred to as a “corresponding portion”) corresponding to the lower opening  274  of the supporter body  271  is not surrounded. 
     If the lower tray body  251  has a complete hemispherical shape, when the expansive force of the water is applied to the corresponding portion of the lower tray body  251  corresponding to the lower opening  274 , the corresponding portion of the lower tray body  251  is deformed toward the lower opening  274 . 
     In this case, although the water supplied to the ice chamber  111  exists in the spherical shape before the ice is made, the corresponding portion of the lower tray body  251  is deformed after the ice is made. Thus, additional ice having a projection shape may be made from the spherical ice by a space occurring by the deformation of the corresponding portion. 
     Thus, in this embodiment, the convex portion  251   b  may be disposed on the lower tray body  251  in consideration of the deformation of the lower tray body  251  so that the ice has the completely spherical shape. 
     In this embodiment, the water supplied to the ice chamber  111  may not have a spherical shape before the ice is made. However, after the ice is completely made, the convex portion  251   b  of the lower tray body  251  may move toward the lower opening  274 , and thus, the spherical ice may be made. 
     In the present embodiment, since the diameter D 1  of the convex portion  251   b  is smaller than the diameter D 2  of the lower opening  274 , the convex portion  251   b  may be deformed to be located inside of the lower opening  274 . 
     &lt;Upper Ejector&gt; 
     Hereinafter, with reference to the drawings, the structure of the upper ejector and the interlocking structure of the upper assembly and the lower assembly will be described in more detail. 
       FIG. 31  is a perspective view illustrating the ice maker from which the upper case is removed as viewed from a side, and  FIG. 32  is a perspective view illustrating the ice maker from which the upper case is removed as viewed from the other side. 
       FIG. 33  is a side view illustrating a state of the lower tray and the upper ejector,  FIG. 34  is a side view illustrating a state where the lower tray is rotated and the upper ejector is lowered in the state of  FIG. 33 ,  FIGS. 35 a  to 35 b    are side views illustrating a state of the additional rotation operation of the lower tray,  FIG. 36A to 36   c  is a side view illustrating the position of the lower tray according to the rotation angle of the first link,  FIG. 36A to 36C  is a side view illustrating a state where the lower tray is further rotated by the elastic member,  FIG. 37  is a perspective view illustrating a coupling state of the upper ejector and the second link,  FIG. 38  is a bottom perspective view illustrating the upper ejector,  FIG. 39  is a perspective view illustrating the first link viewed from one side, and  FIG. 40  is a perspective view illustrating the second link as viewed from the other side. 
     As illustrated, the ice maker  100  according to the present disclosure may further include an upper ejector  300  so that the ice can be separated from the upper assembly  110 . 
     The upper ejector  300  may include an ejector body  310  and a plurality of upper ejecting pins  320  extending in a direction intersecting the ejector body  310 . 
     For example, the upper ejector body  310  may be formed in a horizontal direction, and the upper ejecting pin  320  may be formed to extend in a vertical direction from the lower side of the ejector body  310 . 
     A plurality of grooves may be formed in the upper ejector body  310  along the longitudinal direction. A plurality of reinforcing ribs  311  may be formed in the groove. The reinforcing rib  311  may be formed to be parallel to the longitudinal direction of the upper ejector body  310 . In addition, the reinforcing rib  311  may be formed in a direction intersecting the longitudinal direction of the upper ejector body  310 . 
     In addition, a hollow  321  may be formed in the upper ejecting pin  320 . Thus, the strength of the upper ejecting pin  320  can be improved. 
     In addition, for the ice-separation, when the lower end of the upper ejecting pin  320  presses the spherical upper tray  150 , that is, the upper side of the ice chamber  111 , the stable contact is possible by the hollow  321 . 
     Both ends of the upper ejector body  310  may be provided with a separation prevention protrusion  312  for preventing the upper ejector body  310  from being separated from the connection unit  350  in a state of being coupled to the connection unit  350 . 
     For example, a pair of separation prevention protrusions  312  may protrude in opposite directions to each other from the upper ejector body  310 . 
     In detail, at both ends of the upper ejector body  310 , a separation prevention protrusion  312  protruding in a direction intersecting the upper ejector body  310  may be formed. 
     The separation prevention protrusion  312  may include a circular central portion  312   a  and a pair of protrusion portions  312   b  protruding in the radial direction of the central portion  312   a  from both sides of the central portion  312   a.    
     In addition, the upper and lower guide  313  to guide the vertical movement of the upper ejector body  310  may be provided adjacent to the separation preventing projection  312 . 
     As an example, a pair of upper and lower guide  313  may be provided in parallel with the separation prevention protrusion  312  at both ends of the upper ejector body  310 , and the separation prevention protrusion  312  may be further provided outside. 
     In detail, the upper and lower guide  313  may be inserted into the guide slots  183  corresponding to the width of the guide slots  183 , and guide the movement of the upper ejector  300  along the guide slots  183  in the vertical direction. 
     In addition, the upper and lower guide  313  may have a vertical cross-section formed in a rectangular shape to limit the rotation of the upper ejector  300 . This is to allow the upper ejecting pin  320  to flow into the inlet opening  154  of the upper tray  150  in the correct position. 
     When the upper and lower guide  313  moves up and down along the guide slots  183  in order to allow the upper ejecting pins  320  to be inserted into the inlet openings  154  of the upper tray  150  in the correct position, the flow in the front and rear direction or in the left and right direction should be minimum, and for this purpose, the vertical length, that is, the height of the upper and lower guide  313  may be increased. 
     In other words, it is possible to prevent the flow of the upper ejector body  310  by increasing the contact area between the upper and lower guide  313  and the guide slot  183 . 
     For example, the vertical length of the upper and lower guide  313  may be formed to be larger than the diameter of the central portion  312   a  of the separation prevention protrusion  312  to be adjacently coupled. 
     In addition, the upper and lower guides  313  may extend toward the lower portion of the upper ejector  300  so that interference does not occur when the upper ejector  300  moves up and down. The lower end portion of the upper and lower guides  313  may be located lower than the bottom surface of the upper ejector body  310 . 
     At this time, a portion of the upper and lower guide  313  may be inserted into the interference prevention grooves  126   a  and  126   b  of the upper case  120  in order to prevent interference between the lower end portion of the upper and lower guides  313  and the upper case  120 . Therefore, the vertical movement distance of the upper ejector  300  may be prevented from decreasing. 
     The upper and lower guide  313  may further include an inclined portion  313   a  to guide the insertion of a portion of the upper and lower guide  313  into the interference prevention grooves  126   a  and  126   b  of the upper case  120 . 
     As an example, in the inclined portion  313   a,  a surface toward the center of the upper ejector body  310  of the lower end portion of the pair of upper and lower guides  313  may be inclined in a direction toward the outside. 
     In addition, the pair of upper and lower guide  313  including the inclined portion  313   a  may be formed in a symmetrical shape with respect to the center of the upper ejector body  310 . 
     The upper ejector  300  is connected to the lower assembly  200  to be interlocked with each other when the lower assembly  200  is rotated, the upper ejector  300  can be lifted and lowered. 
     For example, after the ice-making is completed, if the lower assembly  200  is rotated downward to be spaced apart from the upper assembly  110  for the ice-separation, the upper ejector  300  may be lowered. 
     In addition, after the ice-separation is completed, when the lower assembly  200  is rotated upward to be coupled with the upper assembly  110  for water-supply, the upper ejector  300  may be lifted. 
     At the time of the ice-separation, when the upper ejector  300  is lowered, the ice that is in close contact with the upper assembly  110  may be separated from the upper assembly  110 . 
     The upper ejector  300  is connected to the lower assembly  200  by the connection unit  350 . 
     The connection unit  350  includes a first link  352  for rotating the lower supporter  270  by receiving power from the driving unit  180 . Therefore, when the driving unit  180  is operated, the first link  352  and the lower supporter  270  rotate at the same time. 
     The lower supporter  270  forms hinge bodies  281  and  282  on both sides, and the second hinge holes  281   a  are formed in the hinge bodies  281  and  282 , respectively. 
     The shaft connection portion  353  of the first link  352  can pass through the second hinge hole  281 . 
     In addition, the connection shaft  370  may be connected to the shaft connection portion  353 . 
     The shaft connection portion  353  has a polygonal shaft connection groove  353   c  on the opposite surface, and the shaft connection portion  353  may be connected by a connection shaft  370  having a polygonal cross-section with both ends inserted into the shaft connection groove  353   c.    
     For example, the shaft connection portion  353  may include a shaft connection groove  353   c  having a square cross-section on an opposing surface, and the cross-section of the connection shaft  370  may have a square cross-section. 
     The second hinge hole  281   a  may have a free space in the rotation direction of the shaft connection portion  353  in a state where the shaft connection portion  353  is coupled to the second hinge hole  281   a.    
     Referring to the drawings, the shaft connection portion  353  may include a first circular central portion  353   a  and a first engaging portion  353   b  protruding in the radial direction from both sides of the first central portion  353   a,  and the second hinge hole  281   a  may include a second circular central portion  281   b  and a second engaging groove  281   c  which communicates with the second central portion  281   b  and is formed to be recessed outward in a radial direction from both sides of the second central portion  281   b.    
     In addition, the width of the second locking groove  281   c  may be larger than the width of the first locking portion  353   b.    
     In a state where the first engaging portion  353   b  is inserted into the second engaging groove  281   c,  the second engaging groove  281   c  may have a free space in the rotation direction of the first engaging portion  353   b.    
     In addition, the first link  352  and the lower supporter  270  may be connected by the elastic member  360 . The elastic member  360  provides a tension force between the first link  352  and the lower supporter  270 . For example, the elastic member  360  may be a coil spring. As another example, the elastic member  360  may be a tension spring. 
     One end of the elastic member  360  is connected to the first link  352 , and the other end thereof is connected to the lower supporter  270 . 
     The elastic member  360  provides an elastic force for pulling the lower supporter  270  toward the upper tray  150  so that a state where the elastic member is in contact with the upper tray  150  and the lower tray  250  is maintained. 
     The first link  352  may have a coupling hole  352   d  at which one end portion of the elastic member  360  is coupled to one end portion thereof. In addition, the first link  352  may be formed with a coupling groove  352   d  to which the end portion of the elastic member  360  is coupled at one end portion. 
     Referring to  FIGS. 35 a  to 36 c   , after the ice-separation is completed, while the driving unit  180  is operated, the shaft connection portion  353  rotates, and the first link  352  rotates together with the shaft connection portion  353 . In addition, while the first link  352  rotates, the lower supporter  270  also rotates upward by the elastic member  360  to reach the position of  FIG. 36A . In detail, when the first link  352  connected to the driving unit  180  rotates in the clockwise direction (see  FIG. 36A ), the upper end of the first link  352  also rotates in the clockwise direction, and the lower supporter  270  also rotates in the clockwise direction by the elastic member  360  connecting the upper end of the first link  352  and the lower end of the lower supporter  270  to each other. 
     In addition, when the lower supporter  270  reaches the position of  FIG. 36A , the drive unit  180  stops the operation, and the water-supply proceeds. 
     As illustrated, when the water-supply is in progress, the upper end of the lower supporter  270  and the lower end of the upper supporter  170  may be in a state of being spaced apart from each other. 
     In the water-supply position as described above, the upper surface of the lower tray  250  is also spaced apart from the lower surface of the upper tray  150 . 
     Although not limited, the angle formed by the upper surface of the lower tray  250  and the lower surface of the upper tray  150  at the water-supply standby position of the lower assembly  200  may be about 8 degrees. 
     After that, when the water-supply is completed, the driving unit  180  is re-operated. 
     Then, the shaft connection portion  353  rotates in a clockwise direction together with the driving unit  180 , and the first link  352  rotates together with the shaft connection portion  353 . In addition, while the first link  352  rotates, the lower supporter  270  also rotates upward by the elastic member  360  to reach the positions of  FIGS. 35 a    and  36   b.    
     At this time, the upper surface of the lower tray  250  and the lower surface of the upper tray  150  is in contact with each other. Although not limited, in the states of  FIGS. 35 a  and 36 b   , the lower end of the upper tray  150  and the upper end of the lower tray  250  may be in a state of being horizontal. 
     Meanwhile, in the states of  FIGS. 35 a  and 36 b   , although the upper tray  150  and the lower tray  250  are in contact with each other, there is a concern that the upper tray  150  and the lower tray  250  may not be completely in contact with each other. In addition, there is a fear that the coupling force is weakened. 
     Thus, as illustrated in  FIGS. 35 b  and 36 c   , the drive unit  180  is additionally operated, the shaft connection portion  353  rotates in a clockwise direction together with the drive unit  180 , and the first link  352  rotates together with the shaft connection portion  353 . 
     At this time, since the lower tray  250  is in a state of being contact with the upper tray  150 , the lower tray  250  does not rotate any more, and only the elastic member  360  is extended. In addition, the elastic restoring force of the elastic member  360  is increased, and the lower tray  250  may maintain a state of being in contact with the upper tray  150  by the elastic restoring force of the elastic member  360 . 
     Referring to  FIGS. 35 a  to 35 b   , the width of the first engaging groove  281   c  formed in the second hinge hole  281   a  is greater than the width of the first engaging portion  353   b  formed in the shaft connection portion  353 . In addition, the shaft connection portion  353  may be independently rotated in the counterclockwise direction in a state of being inserted into the second hinge hole  281   a.    
     Therefore, while the lower tray  250  is in contact with the upper tray  150 , in a state where further rotation of the lower tray  250  is difficult ( FIG. 35A  state), when the driving unit  180  is additionally operated, as illustrated in  FIG. 35B , only the shaft connection portion  353  can rotate in the clockwise direction while the shaft connection portion  353  is inserted into the second hinge hole  281   a,  and as a result, the first link  352  can rotate together with the shaft connection portion  353 . 
     In addition, as the elastic member  360  is stretched, the elastic restoring force of the elastic member  360  increases and the lower tray  250  maintains a state of being in contact with the upper tray  150  by the elastic restoring force of the elastic member  360 . 
     In addition, in the ice-making process, a state where the upper tray  150  and the lower tray  250  is in contact with each other may be maintained. 
     After that, in a state of  FIGS. 35 b  and 36 c   , when ice-making is completed, the driving unit  180  operates for ice-separation. At this time, the first link  352  is rotated in the counterclockwise direction (with respect to  FIGS. 35 b  and 36 c   ). In addition, the upper end of the first link  352  rotates in the counterclockwise direction, and in this state, the upper tray  150  and the lower tray  250  remain in contact with each other by the elastic restoring force of the elastic member  360 . At this time, the shaft connection portion  353  rotates independently in the counterclockwise direction in a state of being inserted into the second hinge hole  281   a.    
     After that, when the state of  FIGS. 35 a  and 36 b    is formed, the lower end of the first engaging portion  353   b  formed on the left side of the shaft connection portion  353  is in contact with the first engaging groove  281   c.    
     And, if the drive unit  180  continues to operate, while the shaft connection portion  353  rotates in the counterclockwise direction, the lower end of the first engaging portion  353   b  can rotate the first engaging groove  281   c  in the counterclockwise direction, and as a result, the lower supporter  270  and the lower assembly  200  can rotate in the counterclockwise direction. 
     Subsequently, when the ice-separation is completed, while the driving unit  180  operates, the first link  352  and the lower supporter  270  rotate in the clockwise direction, sequentially performing the processes of  FIGS. 36 a , 36 b   , and  36   c.    
     Meanwhile, the connection unit  350  includes a second link  356  which is connected to the lower supporter  270  to transfer the rotational force of the lower supporter  270  to the upper ejector  300  when the lower supporter  270  rotates. 
     In other words, the upper ejector  300  may be connected to the lower supporter  270  by the second link  356 . 
     Thus, the rotational force of the lower assembly  200  may be transmitted to the upper ejector  300  by the second link  356 . 
     In addition, the upper ejector  300  may be lifted and lowered n a straight line by the unit guides  181  and  182 . 
     As an example, after the ice-making is completed, if the lower assembly  200  rotates downwardly to be spaced apart from the upper assembly  110 , the upper ejector  300  may be lowered. 
     In addition, after the ice-separation is completed, when the lower assembly  200  is rotated upward to be coupled to the upper assembly  110  for water-supply, the upper ejector  300  may be lifted. 
     At the time of the ice-separation, when the upper ejector  300  is lowered, the upper ejecting pin  320  is inserted into the upper chamber  152  through the inlet opening  154 . In addition, the ice in close contact with the upper tray  150  may be separated from the upper tray  150 . 
     For reference, the ejector body  310  of the upper ejector  300  may be lifted and lowered in the guide slot  183  formed in the unit guides  181  and  182 . 
     The upper ejector  300  reaches the highest position in the ice-making state, that is, in the state of  FIGS. 35 b    and  36   c.    
     In addition, when the lower assembly  200  rotates in the counterclockwise direction (with respect to  FIG. 35A to 36   c ) for the ice-separation, the upper ejector  300  is lowered corresponding to the rotation angle of the lower assembly  200 . 
     For example, when the lower tray  250  is in contact with the lower ejector  400 , the upper ejector  300  may reach the lowest position. 
     On the other hand, after the ice-separation is completed, when the lower assembly  200  rotates in the clockwise direction (with respect to  FIG. 35A to 36   c ) for the water-supply and the ice-making, corresponding to the rotation angle of the lower assembly  200 , the upper ejector  300  is lifted. 
     For example, when the lower tray  250  is in contact with the upper tray  150  while forming a state of being horizontal, the upper ejector  300  may reach the highest position. 
     &lt;Lower Ejector&gt; 
       FIG. 41  is a bottom perspective view illustrating a state where the ice maker and the lower ejector are separated according to an embodiment of the present disclosure,  FIGS. 42 to 43  are perspective views of the lower ejector illustrated in  FIG. 41  as viewed from various directions,  FIG. 44  is a bottom perspective view illustrating a state where the ice maker and the lower ejector are separated according to another embodiment of the present disclosure, and  FIGS. 45 to 46  are perspective views of the lower ejector illustrated in  FIG. 44  as viewed from various directions. In addition,  FIG. 47  is a view illustrating the lower ejector according to another embodiment of the present disclosure as viewed from the bottom surface. 
     As described above, the ice maker  100  may further include a lower ejector  400  so that ice which is in close contact with the lower assembly  200  can be separated. 
     In detail, after the ice-making is completed, when the lower assembly  200  rotates while being spaced apart from the upper assembly  110 , the lower ejector  400  presses the lower assembly  200  so that the ice which is in close contact with the lower assembly  200  can be separated from the lower assembly  200 . At this time, the lower ejector  400  can press the lower tray  250 . 
     The lower ejector  400  may be fixed to the upper assembly  110  as an example. 
     The lower ejector  400  may include a lower ejector body  410  and a plurality of lower ejecting pins  420  protruding from the lower ejector body  410 . The lower ejecting pins  420  may be provided in the same number as the ice chamber  111 . 
     The lower ejector body  410  may be coupled to a vertical wall  120   a  extending in the vertical direction from the upper tray  120 . The vertical wall  120   a  forms a rear wall of the ice maker. The lower ejector body  410  may be assembled detachably to the vertical wall  120   a.    
     In addition, the lower ejector body  410  may be formed in parallel with the vertical wall  120   a.  In addition, the lower ejector body  410  may form an inclined surface  410   a  that is inclined with respect to the vertical wall  120   a  on one side facing the lower tray  250 . 
     Meanwhile, the inclined surface  410   a  may be inclined by an angle corresponding to the inclined angle of the lower assembly  200  in a state where the lower assembly  200  is rotated to a side of the lower ejector  400  for the ice-separation. 
     In other words, in a state where the rotation of the lower assembly  200  is completed, the inclined surface  410   a  and the lower end of the lower assembly  200  may be formed side by side. 
     Meanwhile, the vertical wall  120   a  may be formed integrally with the upper case  120  and may be provided separately from the upper case  120 . 
     In addition, the supporter body  271  may include a lower opening  274  for passing through by the lower ejector  400  in the ice-separation process. The lower opening  274  may be formed in each chamber receiving portion  272 . 
     In addition, the lower ejecting pin  420  may be formed equal to the number of a lower chamber  252  which is formed in the lower tray  250 , a chamber receiving portion  272  in which the lower chamber is received, and a lower opening  274  which is formed in the chamber receiving portion  272 . 
     For example, three lower chambers  252  may be formed in the lower tray  250 . In addition, the supporter body  271  is formed with three chamber receiving portion  272  so that three lower chambers  272  are received in the three chamber receiving portion, respectively, and the lower opening  274  may be provided in each chamber receiving portion  272 . In addition, three lower ejecting pins  420  may be provided to press the three lower chambers  252  through each of the lower openings  274 . 
     Thus, in a state where the lower ejector  400  is fixed, when the lower assembly  200  rotates toward the lower ejector  400 , the lower ejecting pin  420  can pass through the lower opening  274  and press the lower tray  250 . In addition, the lower tray  250  may be deformed by the pressing force of the lower ejecting pin  420 , and the ice of the lower chamber  252  may be separated from the lower tray  250 . 
     Meanwhile, the lower ejecting pin  420  may be formed to have at least one short length. 
     For example, three lower ejecting pins  420  may be provided in total. The length of the lower ejecting pins  422  (see  FIG. 47 ) disposed in the center may be shorter than the lower ejecting pins  421  and  423  (see  FIG. 47 ) disposed on both sides. 
     As described above, if the length of any one of the plurality of lower ejecting pins  421 ,  422 , and  423  is short, the load applied to the motor may be reduced during the ice-separation. 
     In detail, when the length of any one of the plurality of lower ejecting pins  421 ,  422 , and  423  has a short length, the lower tray  250  first is in contact with two lower ejecting pin  421  and  423  and later is in contact with the other lower ejecting pin  422  in a process in which the lower assembly  200  rotates. 
     In addition, when the lower assembly  200  is continuously rotated, the two lower ejecting pins  421 ,  423  press the lower tray  250 , and the other lower ejecting pin  422  later presses the lower tray  250 . 
     In addition, the ice of the lower tray  250  which is first pressed by the two lower ejecting pins  421  and  423  may be separated from the surface of the lower tray  250 , and then by the middle lower ejecting pin  422 , the ice in the lower tray  250  which is later pressed may be separated from the surface of the lower tray  250 . 
     In other words, the ice of the lower tray  250  may be sequentially separated from the surface of the lower tray  250 . 
     Therefore, while the load applied to the motor included in the drive unit  180  providing the rotational power to the lower assembly  200  is distributed with a time difference, the load applied to the motor can be reduced instantaneously. 
     On the other hand, if the three lower ejecting pins  421 ,  422 , and  423  have the same length, the lower tray  250  is in contact with the three lower ejecting pin  421 ,  422 , and  423  at the same time in a process in which the lower assembly  200  is rotated. 
     In addition, when the lower assembly  200  is continuously rotated, the three lower ejecting pins  421 ,  422 , and  423  simultaneously press the lower tray  250  to deform the lower tray  250 , and the pressing force of the three lower ejecting pins  421 ,  422 , and  423  are transferred to the ice so that three pieces of ice can be separated from the surface of the lower tray  250  almost at the same time. 
     At this time, the load applied to the motor included in the drive unit  180  has to be increased. 
     In addition, the lower ejecting pin  420  may include a pin body  420   a  protruding from the lower ejector body  410  and a pressing portion  420   b  extending from the pin body  420   a.    
     For example, the pin body  420   a  and the pressing portion  420   b  may be bent to form a predetermined angle, and the pressing portion  420   b  can extend from the pin body  420   a  so as to press the center of the lower tray  250 . 
     In detail, the pin body  420   a  may be formed in a curved shape and may be inclined downward from one side connected to the lower ejector body  410  to the other side. 
     As another example, the pin body  420   a  may be inclined downward from one side connected to the lower ejector body  410  to the other side, and at least a portion thereof may be rounded in a curved shape. 
     As another example, the pin body  420   a  is inclined downward from one side connected to the lower ejector body  410  to the other side, and at least a portion of the pin body  420   a  may be rounded in a curved shape so as to position on the extension line of the rotation trajectory of the lower assembly  200 . 
     The pressing portion  420   b  may extend from the pin body  420   a  and be formed to be in contact with the center of the lower tray  250  and rotate when the lower assembly  200  rotates for the ice-separation. 
     In detail, the pressing portion  420   b  may be connected to form a predetermined angle with the pin body  420   a  so that the area in contact with the center of the lower tray  250  is widened. 
     In addition, the pressing portion  420   b  may include a pressing inclined portion  420   c  in contact with the lower tray  250 . 
     For example, as the length of the upper end portion of the pressing portion  420   b  is formed longer than the length of the lower end portion, the pressing inclined portion  420   c  may be formed. 
     The pressing inclined portion  420   c  may be formed such that an upper end portion of the pressing inclined portion  420   c  is in contact with the lower tray  250  first during the ice-separation process. 
     If the lower tray  250  is rotated in a state where the pressing inclined portion  420   c  is not formed in the pressing portion  420   b,  the lower end portion of the pressing portion  420   b  is in contact with the lower tray  250  first. In this case, only a portion of the pressing portion  420   b  presses the lower tray  250  or deformation of the lower tray  250  occurs at a position spaced apart from the central portion of the lower tray  250 , and thus the ice-separation performance can be deteriorated. 
     However, when the pressing inclined portion  420   c  is formed in the pressing portion  420   b  as in the present embodiment, during the rotation of the lower tray  250 , the upper end portion of the pressing inclined portion  420   c  may be first in contact with the lower tray  250 , or the upper end portion and the lower end portion of the pressing inclined portion may be simultaneously in contact with the lower tray. 
     For example, the pressing inclined portion  420   c  is in contact with the lower tray  250  and when the pressing inclined portion reaches the lower limit value (about, 112 degrees) of the rotation angle of the lower assembly  200 , the pressing inclined portion  420   c  may be formed to coincide with the centerline of the lower tray  250 . 
     In a case where the pressing inclined portion  420   c  is formed as described above, when the upper end portion of the pressing inclined portion  420   c  is first contacted or the upper portion and the lower portion thereof are simultaneously contacted, the pressing portion  420   b  can press the central portion of the lower tray and thus the ice-separation performance is improved. 
     In addition, as described above, in a state where the pressing portion  420   b  is in contact with the center of the lower tray  250  when the lower assembly  200  further rotates, the pressing force is continuously applied to the center of the lower tray  250  and thus there is a beneficial advantage to the ice-separation. 
     In addition, the pressing portion  420   b  may form a recessed groove portion  424  at an end portion contacting the lower tray  250 . 
     Thus, the strength of the lower ejecting pin  420  can be improved. In addition, for the ice-separation, when the pressing portion  420   b  presses the spherical lower tray  250 , that is, the convex lower side of the lower chamber  111 , stable contact is possible by the groove portion  424  and a problem that a force is concentrated on one place and thus ice breaks can be prevented. 
     There is a fear that if the end portion of the pressing portion  420   b  is a flat surface, the lower ejecting pin  420  is in point contact with the spherical lower chamber  111 , and while the contact area is reduced, the pressing force may not be properly transmitted. Alternatively, there is a fear that while the force is concentrated in one place, the ice breaks. 
     On the other hand, in a case of the present disclosure, there are advantages that while the recessed groove portion  424  is formed in the pressing portion  420   b,  the lower ejecting pin  420  may be in line contact or surface contact with the spherical lower chamber  111  and while the contact area increases, the pressing force is properly transmitted. In addition, as the force is dispersed, there is an advantage that can prevent the problem of breaking the ice. 
     In addition, at least one reinforcing long hole  425  may be provided on a bottom surface of the pin body  420   a  of the lower ejecting pin  420 . 
     In addition, when the lower assembly  200  rotates for the ice-separation by extending the length of the lower ejecting pin  420 , the sufficient pressing force can be transmitted to the lower chamber  111  even if the lower assembly  200  does not reach the maximum ice-separation position (about 115 degrees) by the tolerance of the motor gear included in the drive unit  180 . 
     Meanwhile, the lower ejector  400  may be coupled with the vertical wall  120   a  in various ways. 
     Referring to  FIGS. 41 and 44 , when the lower assembly  200  rotates for to ice-separation, the vertical wall  120   a  may be formed with the protrusion portion  121   a  protruding forward toward the lower tray  250  at one surface facing the lower tray  250 . 
     In addition, the lower end of the protrusion portion  121   a  may form a cavity  122   a  recessed to the rear. In addition, the lower ejector body  410  of the lower ejector  400  may be received in the cavity  122   a.  Therefore, the lower ejector body  410  may be located under the protrusion portion  121   a.    
     In addition, the cavity  122   a  may form guide slots  123   a  on both sides. In addition, guide protrusions  415  which are inserted into the guide slot  123   a  while being slid along the guide slot may be formed on both sides of the lower ejector body  410 . 
     Thus, the lower ejector body  410  may be coupled while sliding upward from the lower side of the vertical wall  120   a.  At this time, the guide protrusions  415  at both sides of the lower ejector body  410  are inserted into the guide slots  123   a  formed at both sides of the cavity  122   a.    
     In addition, in a state where the lower ejector body  410  is slid along and coupled to the vertical wall  120   a  as described above, by using a fastening means  430 , such as bolts, screws, or the like, the lower ejector body  410  can be coupled to the upper surface  122   b  of the cavity  122   a.    
     For this purpose, the lower ejector body  410  may be provided with a fastening groove portion  416  recessed from the front to the rear. A fastening hole  416   a  through which the fastening means  430  passes may be formed on an upper surface of the fastening groove portion  416 . 
     In addition, the fastening groove portion  416  may be formed on the inclined surface  410   a.  The fastening groove portion  410   a  may have a form in which the width in the front and rear direction thereof gradually decreases from the upper portion to the lower portion. 
     In addition, the fastening groove portion  416  may be formed between the lower ejecting pins  420 . 
     When the fastening groove portion  416  is formed as described above, in a state where the upper surface of the fastening groove portion  416  and the upper surface  122   b  of the cavity  122   a  are in surface contact with each other, the upper surface of the fastening groove portion  416  and the upper surface  122   b  of the cavity  122   a  are fastened from below the fastening groove portion  416  with the fastening means  430 , and thus the lower ejector body  410  can be more easily fixed to the vertical wall  120   a.  In addition, the lower ejector  400  can be coupled to the vertical wall  120   a  without the fastening portion being exposed to the outside. 
     Referring to  FIG. 41 , a coupling groove portion  122   c  upwardly recessed may be further formed at a lower end of the vertical wall  120   a.    
     In addition, in a state where the lower ejector body  410  is slid and coupled to the vertical wall  120   a,  using fastening means  430  such as bolts and screws, the lower ejector body  410  can be coupled to an upper surface  122   d  of the coupling groove portion  122   c.    
     To this end, the lower ejector body  410  may form an extension portion  417  protruding rearward from the lower end. In addition, by the extension portion  417 , the lower ejector body  410  may have a coupling step  418  facing the upper surface of the coupling groove portion  122   c  at the lower end of the rear surface. A fastening boss  417   b  having a fastening hole  417   a  may be formed in the extension portion  417 . 
     When the coupling groove portion  122   c  and the extension portion  417  are formed as described above, in a state where the upper surface  122   d  of the coupling groove portion  122   c  and the coupling step  418  are in surface contact with each other, the lower ejector body  410  may be more easily fixed to the vertical wall  120   a  by fastening the upper surface  122   d  of the coupling groove portion  122   c  and the extension portion  417  with the fastening means  430  from below the extension portion  417 . In addition, the lower ejector  400  may be coupled to the vertical wall  120   a  without the fastening portion being exposed to the outside. 
     When the lower ejector  400  is provided as described above, even if ice is not separated from the lower tray  250  by the own weight of the ice in a process of rotating the lower assembly  200  for the ice-separation, the lower tray  250  is pressed by the lower ejector  400 , and as a result, ice in the lower chamber  252  may be separated from the lower tray  250 . 
     In detail, the lower tray  250  is in contact with the lower ejecting pin  420  in a process in which the lower assembly  200  is rotated toward the lower ejector  400 . 
     In addition, when the lower assembly  200  is continuously rotated in the side of lower ejector  400 , and the lower ejecting pin  420  presses the lower tray  250  and thus the lower tray  250  is modified, and the pressing force of the lower ejecting pin  420  may be transferred to the ice to separate the ice from the surface of the lower tray  250 . The ice separated from the surface of the lower tray  250  may be dropped down and stored in the ice bin  102 . 
     At the time of rotation of the lower assembly  200  for the ice-separation described above, there is a fear that the lower assembly  200  does not reach the maximum ice-separation position (about 115 degrees) by the tolerance of the motor gear included in the drive unit  180 . In this case, a problem arises that the ice-separation does not proceed completely. Therefore, the control may be performed to further rotate the motor included in the driving unit  180  so that the lower assembly  200  may exceed the maximum ice-separation position (about 115 degrees) so as to perform securely the ice-separation. 
     Hereinafter, a process of making ice by using the ice maker according to an embodiment will be described. 
       FIG. 48  is a sectional view taken along the line B-B of  FIG. 3A  in the water-supply state, and  FIG. 49  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-making state. 
       FIG. 50  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-making state,  FIG. 51  is a sectional view taken along the line B-B of  FIG. 3A  in an initial ice-separation state, and  FIG. 52  is a sectional view taken along the line B-B of  FIG. 3A  in an ice-separation completion state. 
     Referring to  FIGS. 48 to 52 , first, the lower assembly  200  rotates to a water supply standby position. 
     The top surface  251   e  of the lower tray  250  is spaced apart from the bottom surface  151   e  of the upper tray  150  at the water supply standby position of the lower assembly  200 . 
     Although not limited, the lower surface  151   e  of the upper tray  150  may be located at the same or similar height as the rotation center C 2  of the lower assembly  200 . 
     In this embodiment, the direction in which the lower assembly  200  rotates (in a counterclockwise direction in the drawing) is referred to as a forward direction, and the opposite direction (in a clockwise direction) is referred to as a reverse direction. 
     Although not limited, an angle between the top surface  251   e  of the lower tray  250  and the bottom surface  151   e  of the upper tray  150  at the water supply standby position of the lower assembly  200  may be about 8 degrees. 
     In this state, the water is guided by the water supply portion  190  and supplied to the ice chamber  111 . 
     Here, the water is supplied to the ice chamber  111  through one inlet opening of the plurality of inlet openings  154  of the upper tray  150 . 
     In the state where the supply of the water is completed, a portion of the water may be fully filled into the lower chamber  252 , and the other portion of the supplied water may be fully filled into the space between the upper tray  150  and the lower tray  250 . 
     Another portion of the water may be filled in the upper chamber  151 . Of course, the water may not be located in the upper chamber  152  after completion of water-supply according to the angle formed between the upper surface  251   e  of the lower tray  250  and the lower surface  151   e  of the upper tray  150  or the volume of the lower chamber  252  and the upper chamber  152 . 
     In the case of this embodiment, a channel for communication between the three lower chambers  252  may be provided in the lower tray  250 . 
     As described above, although the channel for the flow of the water is not provided in the lower tray  250 , since the top surface  251   e  of the lower tray  250  and the bottom surface  151   e  of the upper tray  150  are spaced apart from each other, the water may flow to the other lower chamber along the top surface  251   e  of the lower tray  250  when the water is fully filled in a specific lower chamber in the water supply process. 
     Thus, the water may be fully filled in each of the plurality of lower chambers  252  of the lower tray  250 . 
     In addition, in the case of this embodiment, since the channel for the communication between the lower chambers  252  is not provided in the lower tray  250 , additional ice having a projection shape around the ice after the ice-making process may be prevented being made. 
     In the state where the supply of the water is completed, as illustrated in  FIG. 42 , the lower assembly  200  rotates reversely. When the lower assembly  200  rotates reversely, the top surface  251   e  of the lower tray  250  is close to the bottom surface  151   e  of the upper tray  150 . 
     Thus, the water between the top surface  251   e  of the lower tray  250  and the bottom surface  151   e  of the upper tray  150  may be divided and distributed into the plurality of upper chambers  152 . 
     In addition, when the top surface  251   e  of the lower tray  250  and the bottom surface  151   e  of the upper tray  150  are closely attached to each other, the water may be fully filled in the upper chamber  152 . 
     In the state where the top surface  251   e  of the lower tray  250  and the bottom surface  151   e  of the upper tray  150  are closely attached to each other, a position of the lower assembly  200  may be called an ice-making position. 
     In the state where the lower assembly  200  moves to the ice-making position, ice-making is started. 
     Since the pressing force of water during ice-making is less than the force for deforming the convex portion  251   b  of the lower tray  250 , the convex portion  251   b  may not be deformed to maintain its original shape. 
     When the ice-making is started, the lower heater  296  is turned on. When the lower heater  296  is turned on, the heat of the lower heater  296  is transferred to the lower tray  250 . 
     Thus, when the ice-making is performed in the state where the lower heater  296  is turned on, ice may be made from the upper side in the ice chamber  111 . 
     In other words, water in a portion adjacent to the inlet opening  154  in the ice chamber  111  is first frozen. Since ice is made from the upper side in the ice chamber  111 , the bubbles in the ice chamber  111  may move downward. 
     Since the ice chamber  111  is formed in a spherical shape, the horizontal cross-sectional area is different for each height of the ice chamber  111 . 
     Thus, the output of the lower heater  296  may vary according to the height at which ice is generated in the ice chamber  111 . 
     As the horizontal cross-sectional area is increased from the upper side to the lower side, the horizontal cross-sectional area increases to the maximum at the boundary between the upper tray  150  and the lower tray  250  and decreases to the lower side again. 
     While ice is made from the upper side to the lower side in the ice chamber  111 , the ice may contact a top surface of a block portion  251   b  of the lower tray  250 . 
     In this state, when the ice is continuously made, the block portion  251   b  may be pressed and deformed as illustrated in  FIG. 43 , and the spherical ice may be made when the ice-making is completed. 
     A control unit (not illustrated) may determine whether the ice-making is completed based on the temperature sensed by the temperature sensor  500 . 
     The lower heater  296  may be turned off at the ice-making completion or before the ice-making completion. 
     When the ice-making is completed, the upper heater  148  is first turned on for the ice-removal of the ice. When the upper heater  148  is turned on, the heat of the upper heater  148  is transferred to the upper tray  150 , and thus, the ice may be separated from the surface (the inner face) of the upper tray  150 . 
     After the upper heater  148  has been activated for a set time duration, the upper heater  148  may be turned off and then the drive unit  180  may be operated to rotate the lower assembly  200  in a forward direction. 
     As illustrated in  FIG. 44 , when the lower assembly  200  rotates forward, the lower tray  250  may be spaced apart from the upper tray  150 . 
     In addition, the rotation force of the lower assembly  200  may be transmitted to the upper ejector  300  by the connection unit  350 . Thus, the upper ejector  300  descends by the unit guides  181  and  182 , and the upper ejecting pin  320  may be inserted into the upper chamber  152  through the inlet opening  154 . 
     In the ice-separation process, the ice may be separated from the upper tray  250  before the upper ejecting pin  320  presses the ice. In other words, the ice may be separated from the surface of the upper tray  150  by the heat of the upper heater  148 . 
     In this case, the ice may rotate together with the lower assembly  250  in the state of being supported by the lower tray  250 . 
     Alternatively, even though the heat of the upper heater  148  is applied to the upper tray  150 , the ice may not be separated from the surface of the upper tray  150 . 
     Thus, when the lower assembly  200  rotates forward, the ice may be separated from the lower tray  250  in the state where the ice is closely attached to the upper tray  150 . 
     In this state, while the lower assembly  200  rotates, the upper ejecting pin  320  passing through the inlet opening  154  may press the ice closely attached to the upper tray  150  to separate the ice from the upper tray  150 . The ice separated from the upper tray  150  may be supported again by the lower tray  250 . 
     When the ice rotates together with the lower assembly  250  in the state where the ice is supported by the lower tray  250 , even though external force is not applied to the lower tray  250 , the ice may be separated from the lower tray  250  by the self-weight thereof. 
     While the lower assembly  200  rotates, even though the ice is not separated from the lower tray  250  by the self-weight thereof, as in  FIG. 45 , when the lower tray  250  is pressed by the lower ejector  400 , the ice may be separated from the lower tray  250 . 
     Particularly, while the lower assembly  200  rotates, the lower tray  250  may contact the lower ejecting pin  420 . 
     In addition, when the lower assembly  200  continuously rotates forward, the lower ejecting pin  420  may press the lower tray  250  to deform the lower tray  250 , and the pressing force of the lower ejecting pin  420  may be transmitted to the ice to separate the ice from the lower tray  250 . The ice separated from the surface of the lower tray  250  may drop downward and be stored in the ice bin  102 . 
     After the ice is separated from the lower tray  250 , the lower assembly  200  may be rotated in the reverse direction by the drive unit  180 . 
     When the lower ejecting pin  420  is spaced apart from the lower tray  250  in a process in which the lower assembly  200  is rotated in the reverse direction, the deformed lower tray may be restored to its original form. 
     In addition, in the reverse rotation process of the lower assembly  200 , the rotational force is transmitted to the upper ejector  300  by the connection unit  350 , such that the upper ejector  300  is raised, and thus, the upper ejecting pin  320  is removed from the upper chamber  152 . 
     As described above, while the lower assembly  200  is rotated in the reverse direction by the drive unit  180 , the upper end of the lower assembly  200  is rotated to the first position. 
     At this time, although the upper tray  150  and the lower tray  250  are in contact with each other, there is a fear that the upper tray  150  and the lower tray  250  may not be completely in contact with each other. 
     In this state, when the driving unit  180  is stopped, the lower assembly  200  is pulled upward by the tensile force of the elastic member  360 , the upper end of the lower assembly  200  rotates up to the second position higher than the first position, and as a result, the upper tray  150  and the lower tray  250  may be more completely coupled to each other. 
     In addition, when the lower assembly  200  reaches the water supply standby position, the drive unit  180  is stopped, and then the water supply starts again.