Patent Publication Number: US-11378329-B2

Title: Entrance refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefits of priority to Korean Patent Application No. 10-2019-0021867, filed on Feb. 25, 2019, and Korean Patent Application No. 10-2019-0086984, filed on Jul. 18, 2019, all of which are herein incorporated by reference in their entireties. 
     BACKGROUND 
     The present disclosure relates to a refrigerator installed at an entrance of a building, such as a home or a business. 
     Recently, delivery services for delivering fresh goods to predetermined places are being utilized. In particular, when the goods are fresh food, a delivery vehicle is provided with a refrigerator or a warmer to store and deliver the food so as to prevent the food from spoiling or cooling. 
     Generally, the food is packed in a packaging material and delivered so as to keep the food cool or warm, depending on the type of food. The packaging material is often composed of environmental pollutants such as polystyrene foam. The social atmosphere recently has placed an emphasis on a reduction of an amount of packaging material used. 
     When a user is at home at the time of a delivery, the delivery person may deliver the food to the user in a face-to-face manner. However, when the user is not at home or when the delivery time is too early or too late, it is difficult for the delivery person to deliver the food in a face-to-face manner. 
     Therefore, there is a need to be able to deliver the food even if the delivery person does not face the user, and to prevent the food from spoiling or cooling until the food is finally delivered to the user. 
     To solve this problem, in recent years, a product has been introduced in which a refrigerator is installed at an entrance (e.g. a front door) of a predetermined place, so that a delivery person can deliver the food into the refrigerator in order to keep the food fresh until a user can receive the food by accessing the refrigerator at a convenient time. 
     Korean Patent Application Publication No. 2011-0033394 (Mar. 31, 2011) discloses an entrance refrigerator mounted on a front door. 
     The reference discloses a thermoelectric module used to keep a temperature of a storage compartment low. However, the reference does not disclose an arrangement for discharging high-temperature air generated from a heat generating side of the thermoelectric module to the outside. 
     In addition, the reference does not disclose an arrangement to discharge heat generated by a control board mounted with the various electrical components to the outside. 
     SUMMARY 
     One embodiment of the present disclosure provides an entrance refrigerator including a cold air supply device using a thermoelectric element, and in which air for cooling a heat generating surface of the thermoelectric element is used as a printed circuit board (PCB) cooling means. 
     In an entrance refrigerator according to one embodiment, a PCB on which heat generating components are mounted is disposed inside a housing such that air used to cool a heat sink of a cold air supply device cools the PCB, thereby preventing overheating of the PCB. 
     In addition, in order to concentrate air flowing into the housing toward the PCB, a flow guide plate may be installed on the bottom surface of the housing. 
     In addition, the PCB may be fixed to a position spaced apart upward from a discharge port formed in the bottom of the housing, such that the discharge port is not blocked by the PCB to prevent a flow resistance from occurring. 
     In addition, a controller of the entrance refrigerator according to one embodiment is configured to adjust a rotational speed of a heat dissipation fan depending on an outside temperature of the housing and/or an internal temperature of a storage compartment of the entrance refrigerator, thereby effectively cooling down the PCB and reducing power consumption. 
     The entrance refrigerator configured as described above according to the embodiment has the following effects. 
     First, the entrance refrigerator absorbs heat generated from the heat generating surface of the cold air supply device while passing over the PCB and discharges the absorbed heat into the room, thereby preventing overheating of the PCB. 
     Second, among the electrical components mounted on the PCB, components with high heat dissipation are disposed in a region with a high air flow rate and a high air flow velocity, thereby preventing overheating of the components mounted on the PCB and ensuring component reliability. 
     Third, a flow guide plate mounted inside the housing may control an air flow direction and an air volume of air forcedly flowing due to the heat dissipation fan, thereby allowing a large amount of air to flow toward components generating a large amount of heat. 
     Fourth, since indoor air discharged after being suctioned by the heat dissipation fan cools the PCB, no additional structure for cooling the PCB is required, thereby reducing power consumption and reducing the manufacturing cost of the entrance refrigerator. 
     Fifth, the air flow speed of the heat dissipation fan is adjusted according to the outside temperature and the temperature of the storage compartment of the entrance refrigerator, thereby reducing power consumption required for driving the cold air supply device. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an entrance refrigerator installed at a front door, according to an embodiment. 
         FIG. 2  is a side view of the entrance refrigerator installed at the front door, according to an embodiment. 
         FIG. 3  is a front perspective view of the entrance refrigerator according to an embodiment. 
         FIG. 4  is a rear perspective view of the entrance refrigerator according to an embodiment. 
         FIG. 5  is a bottom perspective view of the entrance refrigerator according to an embodiment. 
         FIG. 6  is a front perspective view of the entrance refrigerator in a state in which an outdoor side door is removed for clarity of illustration, according to an embodiment. 
         FIG. 7  is a rear perspective view of the entrance refrigerator in a state in which an indoor side door is removed for clarity of illustration, according to an embodiment. 
         FIG. 8  is an exploded perspective view of the entrance refrigerator according to an embodiment. 
         FIG. 9  is a cross-sectional view of the entrance refrigerator, taken along line  9 - 9  of  FIG. 3 . 
         FIG. 10  is a side cross-sectional view of the entrance refrigerator, taken along line  10 - 10  of  FIG. 3 . 
         FIG. 11  is a perspective view of a cabinet constituting the entrance refrigerator, according to an embodiment. 
         FIG. 12  is a side cross-sectional view taken along line  12 - 12  of  FIG. 11 . 
         FIG. 13  is a perspective view of a tray accommodated in a storage compartment of the entrance refrigerator, according to an embodiment. 
         FIG. 14  is a perspective view of a base plate disposed on the bottom of the storage compartment of the entrance refrigerator, according to an embodiment. 
         FIG. 15  is a perspective view of a flow guide disposed on the bottom of the entrance refrigerator, according to an embodiment. 
         FIG. 16  is a perspective view showing the internal structure of a housing of the entrance refrigerator, according to an embodiment. 
         FIG. 17  is a plan perspective view of the housing in which printed circuit boards are disposed, according to an embodiment. 
         FIG. 18  is a bottom perspective view of the housing in which a flow separation plate is attached to a bottom of the housing  15 , according to an embodiment. 
         FIG. 19  is a bottom perspective view of a housing provided with a flow separation plate, according to another embodiment. 
         FIG. 20  is a flowchart describing a heat dissipation fan driving algorithm of a cold air supply device for cooling a PCB. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an entrance refrigerator  10  according to an embodiment will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a front view of an entrance refrigerator  10  according to an embodiment installed at a front door of a building, such as a residence, and  FIG. 2  is a side view of the entrance refrigerator  10  installed at the front door, according to an embodiment. 
     Referring to  FIGS. 1 and 2 , the entrance refrigerator  10  according to the embodiment may be mounted by passing through a suitably-sized opening in a front door  1  or a front wall of a house. 
     In detail, the entrance refrigerator  10  may be mounted at a point spaced apart from a knob  2  of the front door  1 , for example, the entrance refrigerator  10  may be mounted at the center of the front door  1 . 
     In addition, the entrance refrigerator  10  is preferably installed at a height within two meters from the bottom of the front door  1  for convenience of a user and for convenience to a delivery person who delivers goods to the entrance refrigerator  10 . Preferably, the entrance refrigerator  10  may be installed at a height in a range of 1.5 meters to 1.7 meters from the bottom of the front door  1 . 
     One portion of the entrance refrigerator  10  is exposed to the outside O (outdoors), and another portion of the entrance refrigerator  10  is exposed to the inside I (indoors). For example, in the entrance refrigerator  10 , the surface exposed to the outside O may be defined as the front surface (or outdoor portion) at the front side (exterior side) of the door or wall, and the surface exposed to the inside I may be defined as the rear surface (or indoor portion) at the rear side (interior side) of the door or wall. The door or wall provides a barrier in or around a building, such as, but not limited to, a house, apartment, office, hospital, or the like. 
     Hereinafter, the configuration of the entrance refrigerator  10  according to the embodiment will be described in more detail with reference to the accompanying drawings. 
       FIG. 3  is a front perspective view of the entrance refrigerator  10  according to an embodiment,  FIG. 4  is a rear perspective view of the entrance refrigerator  10 , and  FIG. 5  is a bottom perspective view of the entrance refrigerator  10 . 
     Referring to  FIGS. 3 to 5 , the entrance refrigerator  10  according to the embodiment may include a cabinet  11 , an outdoor side door  12 , an indoor side door  13 , and a housing  15 . 
     The cabinet  11  has a front opening provided in a portion of the cabinet  11  located at the front (exterior) side of the door or exterior wall, and a rear opening provided in a portion of the cabinet  11  located at the rear (interior) side of the door or interior wall. The cabinet  11  may have an approximately hexahedral shape with a front wall and a rear wall interconnected by a plurality of side walls. The front opening may be provided in the front wall of the cabinet  11 , and the rear opening may be provided in the rear wall of the cabinet  11 , although the embodiment is not limited thereto. For example, the front opening and the rear opening may be provided on a same side of the cabinet  11  depending on the location where the entrance refrigerator  10  is being installed. The outdoor side door  12  may be rotatably coupled to the cabinet  11  so as to selectively open or close the front opening of the cabinet  11 . The outdoor side door  12  may be opened by the delivery person in order to store goods in the entrance refrigerator  10 . In addition, the outdoor side door  12  may be opened by the user so as to withdraw goods from the entrance refrigerator  10 . 
     Here, the term “user” is defined as a person who has ordered goods that are stored in the entrance refrigerator  10  by the delivery person, or as a person having authority to release the goods from the entrance refrigerator  10 . 
     In addition, the indoor side door  13  may be rotatably coupled to the cabinet  11  so as to selectively open or close the rear opening of the cabinet  11 . 
     A display  14  may be provided on the outdoor side door  12 . The display  14  may display information about an operating state of the entrance refrigerator  10 , an internal temperature of the entrance refrigerator  10 , and the presence or absence of goods in the entrance refrigerator  10 . 
     In addition, the delivery person who delivers goods may input a password or the like through the display  14  for opening the outdoor side door  12 . 
     A code scanner for recognizing an encryption code provided in a shipping order or a shipping box may be provided on one side of the outdoor side door  12 . 
     The indoor side door  13  is used by the user within the house to take out goods stored in the entrance refrigerator  10 . That is, the user can open the indoor side door  13  to withdraw the goods from the entrance refrigerator  10  and into the house. 
     A guide light  131  may be provided at one side of the indoor side door  13 . The guide light  131  may be a device for informing a user whether or not goods are currently stored in the entrance refrigerator  10 . For example, the color of the guide light  131  may be set differently depending on whether goods are stored in the entrance refrigerator  10  or whether the entrance refrigerator  10  is empty. The user may recognize whether there are goods currently being stored even without opening the indoor side door  13 . 
     The housing  15  is provided at the lower end of the cabinet  11 , either integrally as part of the cabinet  11  or as a separate element attached to the cabinet  11 . A cold air supply device  30  (cold air supplier), to be described later, is accommodated in the housing  15 . The front surface of the housing  15  comes into close proximity with the rear surface of the front door  1  or the wall when the entrance refrigerator  10  is mounted on the front door  1  or the wall, and contact between a portion of the front surface of the housing  15  and the rear surface of the front door  1  or the wall cancels the moment due to the eccentric load of the entrance refrigerator  10  within the opening of the front door  1  or the wall. 
     In detail, the entrance refrigerator  10  according to the embodiment has a structural characteristic in which a volume of a part exposed indoors is larger than a volume of a part exposed outdoors of the front door  1 . Therefore, the center of gravity of the entrance refrigerator  10  is formed at a point eccentric rearwardly of the center of the entrance refrigerator  10 . As a result, the moment is generated by the load of the entrance refrigerator  10  and the load of goods stored therein. With such an arrangement, it is possible that the entrance refrigerator  10  could be pulled out of the front door  1  by the moment. 
     However, since the front surface of the housing  15  contacts the rear surface of the front door  1  or the wall, the moment acting on the entrance refrigerator  10  is cancelled, thereby preventing the entrance refrigerator  10  from being separated from the front door  1 . 
     A pair of guide ducts  16  may be provided at left and right edges of the bottom surface of the housing  15 . A discharge port  161  is formed at the front end of each guide duct  16  so that indoor room air, which flows into the cold air supply device  30  in the housing  15  and performs a heat dissipation function, may be discharged out of the housing  15 . 
     A guide plate  18  may be provided on an angled surface of the cabinet  11  formed by the bottom surface of the cabinet  11  and the front surface of the housing  15 . The function of the guide plate  18  will be described below with reference to the accompanying drawings. 
     An opening for suctioning indoor room air may be formed in the bottom surface of the housing  15 , and a suction plate  17  may be mounted at the opening. A plurality of through-holes  171  may be formed in the suction plate  17 , and indoor room air is introduced into the housing  15  through the plurality of through-holes  171 . At least part of the indoor room air introduced into the housing  15  is discharged back out of the housing  15  through the discharge ports  161  of the guide ducts  16 . 
       FIG. 6  is a front perspective view of the entrance refrigerator  10  in a state in which the outdoor side door  12  is removed for clarity of illustration, according to an embodiment, and  FIG. 7  is a rear perspective view of the entrance refrigerator  10  in a state in which the indoor side door  13  is removed for clarity of illustration, according to an embodiment. 
     Referring to  FIGS. 6 and 7 , a storage compartment  111  in which goods may be stored is provided within the cabinet  11 . The storage compartment  111  may be considered as a main body of the entrance refrigerator  10  according to the embodiment. 
     A tray  19  on which goods are placed may be provided at a lower portion of the storage compartment  111 . 
     In addition, a guide rib  25  may be formed along the rear edge of the cabinet  11 . The guide rib  25  may protrude a predetermined distance from the rear surface of the cabinet  11  and extend along an edge of the cabinet  11 . The guide rib  25  is provided to guide some of the air discharged from the housing  15  upwardly to the area surrounding the indoor side door  13  so that condensation is prevented from forming on a gasket  22  surrounding the rear surface of the indoor side door  13 . 
       FIG. 8  is an exploded perspective view of the entrance refrigerator  10  according to an embodiment,  FIG. 9  is a cross-sectional view of the entrance refrigerator  10 , taken along line  9 - 9  of  FIG. 3 , and  FIG. 10  is a side cross-sectional view of the entrance refrigerator  10 , taken along line  10 - 10  of  FIG. 3 . 
     Referring to  FIGS. 8 to 10 , as described above, the entrance refrigerator  10  according to the embodiment may include the cabinet  11 , the indoor side door  13 , the outdoor side door  12 , the housing  15 , the guide duct  16 , the suction plate  17 , and the tray  19 . 
     The entrance refrigerator  10  may further include a base plate  20  disposed at the bottom portion of the cabinet  11 . The tray  19  may be disposed above the base plate  20 . The bottom surface of the tray  19  may be spaced apart upward from the base plate  20 . 
     The entrance refrigerator  10  may further include a cold air supply device  30  accommodated in the housing  15 . 
     The cold air supply device  30  may be a device to which a thermoelectric element (Peltier element) is applied, but the cold air supply device  30  is not limited thereto. For example, a general cooling cycle may be applied to the cold air supply device  30 . 
     When a current is supplied to the thermoelectric element, one surface thereof acts as a heat absorbing surface in which a temperature drops, and the other surface thereof acts as a heat generating surface in which a temperature increases. In addition, when the direction of the current supplied to the thermoelectric element is changed, the heat absorbing surface and the heat generating surface are swapped. 
     In detail, the cold air supply device  30  may include a thermoelectric element  31 , a cold sink  32  attached to the heat absorbing surface of the thermoelectric element  31 , a heat absorption fan  33  disposed above the cold sink  32 , a heat sink  34  attached to the heat generating surface of the thermoelectric element  31 , a heat dissipation fan  36  disposed below the heat sink  34 , and an insulation material  35  for preventing heat transfer between the cold sink  32  and the heat sink  34 . 
     The insulation material  35  is provided to surround the side surface of the thermoelectric element  31 . The cold sink  32  comes into contact with the upper surface of the insulation material  35 , and the heat sink  34  comes into contact with the lower surface of the insulation material  35 . 
     The cold sink  32  and the heat sink  34  may include a thermal conductor directly attached to the heat absorbing surface and the heat generating surface, respectively, of the thermoelectric element  31 , and a plurality of heat exchange fins extending from the surface of the thermal conductor. 
     The heat absorption fan  33  is disposed to face the inside of the cabinet  11 , and the heat dissipation fan  36  is disposed directly above the suction plate  17 . 
     The entrance refrigerator  10  may further include a mount plate  24  mounted on the bottom of the cabinet  11 , and a flow guide  23  mounted on the upper surface of the mount plate  24 . 
     The mount plate  24  may be formed in a shape in which a rectangular plate is bent a plurality of times to include a bottom portion, a pair of upstanding side portions, and a pair of outwardly extending flange portions. The mount plate  24  may be formed in a shape in which a flow guide seating portion  241 , on which the flow guide  23  is seated, is recessed or stepped to a predetermined depth. A through-hole  242  is formed at the bottom portion of the mount plate  24  defining the flow guide seating portion  241 . A portion of the cold air supply device  30  may pass through the through-hole  242  and be mounted to the mount plate  24 . 
     In addition, the flow guide  23  may be understood as a device for forming the flow path of the air inside the storage compartment  111  which forcibly flows by the heat absorption fan  33 . 
     The base plate  20  may be disposed above the flow guide  23  to minimize a possibility that foreign substances could fall directly onto the flow guide  23 . 
     An outer gasket  21  is provided on an inner side of the outdoor side door  12  that faces the cabinet  11 , and an inner gasket  22  is provided on an inner side of the indoor side door  13  that faces the cabinet  11 . The outer gasket  21  and the inner gasket  22  prevent cold air within the storage compartment  111  from leaking to the outside of the entrance refrigerator  10 . Alternatively, the outer gasket  21  may be provided on a portion of the cabinet  11  that faces an inner side of the outdoor side door  12 , and the inner gasket  22  may be provided on a portion of the cabinet  11  that faces an inner side of the indoor side door  13 . The portion of the cabinet  11  may be a contact shoulder  115  to be described later. The outer gasket  21  and the inner gasket  22  prevent cold air within the storage compartment  111  from leaking to the outside of the entrance refrigerator  10 . 
       FIG. 11  is a perspective view of the cabinet  11  constituting the entrance refrigerator  10 , according to an embodiment, and  FIG. 12  is a side cross-sectional view taken along line  12 - 12  of  FIG. 11 . 
     Referring to  FIGS. 11 and 12 , the cabinet  11  constituting the entrance refrigerator  10  according to the embodiment has a hexahedral shape in which the front side and the rear side are opened. 
     The cabinet  11  may include a first portion  112  (exterior portion) inserted through the front door  1  or the wall, and a second portion  113  (interior portion) exposed to the inside. 
     The lower end of the second portion  113  may extend downward further than the lower end of the first portion  112 . In detail, the front surface of the second portion  113  extending downward from the rear end of the bottom of the first portion  112  may be defined as a door contact surface  114 . Like the front surface of the housing  15 , the door contact surface  114  prevents the entrance refrigerator  10  from being separated from the front door  1  or the wall by the moment. 
     A contact shoulder  115  may be formed at a point spaced apart rearward from the front end of the cabinet  11  by a predetermined distance. 
     The contact shoulder  115  may protrude from the inner circumferential surface of the cabinet  11  by a predetermined height, and may have a rectangular band shape extending along the inner circumferential surface of the cabinet  11 . 
     A rectangular opening defined along the inner edge of the contact shoulder  115  may define an inlet portion for goods entering or exiting the storage compartment  111 . 
     A space between the front end of the cabinet  11  and a front surface of the contact shoulder  115  may be defined as an outdoor side door accommodation portion into which the outdoor side door  12  is received. 
     In a state in which the outdoor side door  12  is closed, the outer gasket  21  is in close contact with the front surface of the contact shoulder  115  to prevent leakage of cold air from the storage compartment  111 . 
     The longitudinal cross-section of the storage compartment  111  defined at the rear of the contact shoulder  115  may have the same size as the longitudinal cross-section of the inlet portion. That is, the bottom surface of the storage compartment  111  may be coplanar with the upper edge of the contact shoulder  115  extending from the inner circumferential surface of the bottom portion of the cabinet  11 . The bottom surface of the storage compartment  111  may include the base plate  20 . 
     In addition, the left and right side surfaces of the storage compartment  111  may be coplanar with the inner edges of the contact shoulder  115  extending from the left inner circumferential surface and the right inner circumferential surface of the cabinet  11 , respectively. 
     Finally, the ceiling surface of the storage compartment  111  may be coplanar with the lower edge of the contact shoulder  115  extending from the inner circumferential surface of the upper end of the cabinet  11 . 
     In summary, it can be understood that the inner circumferential surface of the storage compartment  111  is coplanar with the inner edges of the contact shoulder  115 . 
     However, the present disclosure is not limited to the above configuration. For example, the bottom surface of the storage compartment  111  may be coplanar with the bottom surface of the outdoor side door accommodation portion. 
     In detail, the contact shoulder  115  may be described as including a lower shoulder  115   a , a left shoulder  115   b , a right shoulder (see  FIG. 6 ), and an upper shoulder  115   c , and the bottom surface (floor) of the storage compartment  111  may be designed to be lower than the upper edge of the lower shoulder  115   a.    
     In addition, the left and right side surfaces of the storage compartment  111  may be designed to be wider than the inner edges of the left shoulder  115   b  and the right shoulder. 
     Finally, the upper surface (ceiling) of the storage compartment  111  may be designed to be higher than the lower edge of the upper shoulder  115   c.    
     According to this structure, the width and height of the storage compartment  111  may be formed to be larger than the width and height of the inlet portion. 
     A slot  116  may be formed at the bottom of the cabinet corresponding to the bottom of the outdoor side door accommodation portion. 
     The point where the slot  116  is formed may be described as a point spaced a predetermined distance rearward from the front end of the cabinet  11 , or a point spaced a predetermined distance forward from the front surface of the contact shoulder  115 . 
     The slot  116  may be formed at a position closer to the contact shoulder  115  than to the front end of the cabinet  11 . As the air that has a relatively high temperature and is discharged from the housing  15  rises, the air may be introduced into the outdoor side door accommodation portion of the cabinet  11  through the slot  116 . 
     The air flowing through the slot  116  flows along the edge of the outer gasket  21  to evaporate any condensation that may form on the outer gasket  21 . 
     In detail, an inwardly stepped portion  119  may be formed in the bottom surface of the cabinet  11  corresponding to the first portion  112  and in the front surface of the cabinet  11  corresponding to the second portion  113 . The stepped portion  119  is enclosed by the guide plate  18 , and an air flow passage  119   a  is formed between the guide plate  18  and the stepped portion  119 . The lower end of the air flow passage  119   a  communicates with the inside of the housing  15 , and the upper end of the air flow passage  119   a  is connected to the slot  116 . 
     Due to this structure, the relatively high-temperature air discharged from the housing  15  moves along the air flow passage  119   a  and flows into the slot  116 . 
     A mount plate seating portion  117  may be formed at a predetermined depth on the inner bottom surface of the cabinet  11 , particularly on the bottom surface of the cabinet  11  corresponding to the second portion  113 . 
     A cold air suction hole  118  may be formed on the bottom of the mount plate seating portion  117 . The mount plate  24  is mounted on the mount plate seating portion  117  such that the through-hole  242  and the cold air suction hole  118  are aligned in the vertical direction. 
     In addition, the flow guide  23  is disposed above the mount plate seating portion  117 , particularly on the upper surface of the mount plate  24 . 
       FIG. 13  is a perspective view of the tray  19  accommodated in the storage compartment  111  of the entrance refrigerator  10 , according to an embodiment. 
     Referring to  FIG. 13 , the tray  19  according to the embodiment may include a rectangular bottom portion  191 , an edge wall surrounding the edge of the bottom portion  191  and extending to a predetermined height, and legs  196  extending downward from four corners of the bottom portion  191 . 
     A plurality of through-holes  191   a  may be formed in the bottom portion  191 . 
     The edge wall may include a front portion  192 , a left side portion  193 , a right side portion  194 , and a rear side portion  195 . 
     The bottom portion  191  is spaced apart from the bottom of the storage compartment  111  by the legs  196  to form a lower gap g 1 . 
     The height of the lower gap g 1  corresponds to the height of the legs  196 , and the width of the lower gap g 1  corresponds to the distance between two adjacent legs. 
     In addition, the left-to-right width of the bottom portion  191  is formed to be smaller than the left-to-right width of the storage compartment  111 , such that the edge wall of the tray  19  and the sidewall of the storage compartment  111  are separated by a predetermined distance to form a side gap g 2 . The front-to-rear width of the bottom portion  191  may also be formed to be smaller than the front-to-rear width of the storage compartment  111  to form a side gap. 
     The side gap g 2  may be about 5 mm, but the dimension of the gap g 2  is not limited thereto. 
       FIG. 14  is a perspective view of the base plate  20  disposed on the bottom of the storage compartment  111  of the entrance refrigerator  10 , according to an embodiment. 
     Referring to  FIG. 14 , the base plate  20  according to the embodiment may be formed to be the same size as the bottom portion  191  of the tray  19 . Alternatively, the base plate  20  may be formed to be the same size as the bottom portion of the storage compartment  111 . 
     A plurality of through-holes  201  may be formed in the base plate  20 , and the plurality of through-holes  201  may include circular holes or polygonal holes. 
     Referring to  FIGS. 9 to 11 , the base plate  20  may be spaced apart from the bottom surface of the storage compartment  111  by a predetermined interval. 
     The separation distance between the base plate  20  and the bottom surface of the storage compartment  111  is set to a dimension in consideration of the height of the lower shoulder  115   a , so that the upper surface of the base plate  20  and the lower shoulder  115   a  may form the same plane. 
     According to this configuration, when the user or the delivery person withdraws the tray  19  from the storage compartment  111  or inserts the tray  19  into the storage compartment  111 , the lower shoulder  115   a  does not act as an obstacle that prevents the tray  19  from being inserted or withdrawn. 
     That is, there is an advantage that the tray  19  can be pulled out by sliding the tray  19  on the base plate  20 . 
     In addition, since the separation space is formed between the base plate  20  and the bottom surface of the storage compartment  111 , the cold air guided by the flow guide  23  is evenly distributed throughout the lower portion of the storage compartment  111 . 
     The separation distance between the base plate  20  and the bottom surface of the storage compartment  111  may be about 15 mm, but the separation distance is not limited thereto. 
       FIG. 15  is a perspective view of the flow guide  23  disposed on the bottom of the entrance refrigerator  10 , according to an embodiment. 
     Referring to  FIG. 15 , the flow guide  23  according to the embodiment may include a bottom portion  231 , curved portions  235  extending upward from the left and right edges of the bottom portion  231  in a rounded form, extension ends  234  extending downward from the front end and the rear end of the bottom portion  231  and the curved portions  235 , and a fan housing  232  protruding upward from the center of the upper surface of the bottom portion  231 . 
     The extension ends  234  may include a front extension end extending downward from the front end of the bottom portion  231  and the front ends of the curved portions  235 , and a rear extension end extending downward from the rear end of the bottom portion  231  and the rear ends of the curved portions  235 . 
     The ends of the curved portions  235  and the extension ends  234  define side discharge ports at the left and right edges of the flow guide  23 , respectively. 
     In addition, main discharge ports  236  may be formed at points spaced apart from the fan housing  232  to the left and the right of the fan housing  232  by a predetermined distance. The main discharge ports  236  may be formed by a plurality of slits that extend a predetermined length in the left-to-right direction of the flow guide  23  and are spaced apart in the front-to-rear direction of the flow guide  23 . However, the main discharge ports  236  may also be provided in the form of one or more openings elongated in the front-to-rear direction of the flow guide  23 . 
     The fan housing  232  may protrude a predetermined height from the bottom portion  231  so as to accommodate the heat absorption fan  33 . A suction port  233  may be formed in the upper surface of the fan housing  232 . 
     Due to this structure, when the heat absorption fan  33  is rotated, cold air inside the storage compartment  111  is guided toward the cold sink  32  through the suction port  233 . The cold air cooled while passing through the cold sink  32  flows in the horizontal direction of the flow guide  23 . The cold air flowing in the horizontal direction of the flow guide  23  forms a circulation flow path discharged into the storage compartment  111  through the main discharge ports  236  and the side discharge ports  237 . 
     Meanwhile, the left end and the right end of the flow guide  23  are in close contact with the left edge and the right edge of the mount plate seating portion  117 . As a result, the side discharge ports  237  are formed on the upper surface of the flow guide  23 , such that the cold air is discharged upward toward the ceiling of the storage compartment  111 . 
       FIG. 16  is a perspective view showing the internal structure of the housing  15  of the entrance refrigerator  10 , according to an embodiment, and  FIG. 17  is a plan perspective view of the housing  15  in which printed circuit boards are disposed. 
     Referring to  FIGS. 16 and 17 , the housing  15  according to the embodiment is coupled to the lower end of the cabinet  11 , specifically the lower end of the cabinet  11  defined as the second portion  113 . 
     One portion of the cold air supply device  30  is accommodated in the housing  15 , and another portion of the cold air supply device  30  is accommodated in the lower space of the cabinet  11  corresponding to the second portion  113 . 
     In one example, the heat absorption fan  33 , the cold sink  32 , and the thermoelectric element  31  may be accommodated in the lower space of the second portion  113  of the cabinet  11 , and the heat sink  34  and the heat dissipation fan  36  may be accommodated in the housing  15 . However, this arrangement may be changed according to design conditions. 
     The housing  15  may include a bottom portion  151 , a front surface portion  152  extending upward from the front end of the bottom portion  151 , a rear surface portion  153  extending upward from the rear end of the bottom portion  151 , a left surface portion  154  extending upward from the left end of the bottom portion  151 , and a right surface portion  155  extending upward from the right end of the bottom portion  151 . 
     A pair of guide ducts  16  are mounted on the bottom surface of the bottom portion  151 . 
     A suction hole  151   a  is formed at the center of the bottom portion  151 , and a suction plate  17  is mounted over the suction hole  151   a.    
     A left discharge port  158  and a right discharge port  159  are formed on the left edge and the right edge of the bottom portion  151 , respectively. The left discharge port  158  and the right discharge port  159  may be composed of an assembly of circular or polygonal holes. However, the present disclosure is not limited thereto, and each of the left discharge port  158  and the right discharge port  159  may have a rectangular hole shape having a predetermined width and length. 
     The guide ducts  16  are mounted directly below the left discharge port  158  and the right discharge port  159 , respectively. 
     One or more flow guide plates  150  may be disposed on the upper surface of the bottom portion  151  corresponding to four corner portions of the suction hole  151   a . In detail, a plurality of flow guide plates  150  may be disposed at the four corner portions of the suction hole  151   a . A portion of outside air introduced into the housing  15  through the suction plate  17  that exchanges heat with the heat sink  34  may be guided to the left discharge port  158  and the right discharge port  159  by the flow guide plate  150 . 
     A front discharge port  156  and a rear discharge port  157  may be formed at the centers of the front surface portion  152  and the rear surface portion  153 , respectively. A portion of the outside air introduced through the suction plate  17  may exchange heat with the heat sink  34  and may be discharged to the outside through the front discharge port  156  and the rear discharge port  157 . 
     The front discharge port  156  and the rear discharge port  157  may also be defined as an assembly of a plurality of holes, but the present disclosure is not limited thereto. However, since the discharge ports  156 ,  157 ,  158  and  159  are composed of a plurality of holes having a small diameter, it is possible to minimize the introduction of foreign substances into the housing  15 . 
     The guide plate  18  may be coupled to the cabinet  11  as an independent member, or may be a part of the housing  15  extending upward from the upper end of the front surface portion  152  and bent forward. 
     The left surface portion  154  and the right surface portion  155  may extend upward from the left and right edges of the bottom portion  151  in a rounded form. 
     The PCB may be disposed in the housing  15  in order to cool the PCB on which the electrical components generating a large amount of heat are mounted. 
     The electrical components for controlling the driving of at least the cold air supply device  30  may be mounted on the PCB. 
     In detail, the PCB may include a main PCB  41  and a sub PCB  42 , but the present disclosure is not necessarily limited thereto. It is noted that the PCB generating a large amount of heat is disposed on a flow passage of indoor air forcedly flowing due to the heat dissipation fan  36  such that the PCB is naturally cooled. 
     The main PCB  41  may be disposed above the left discharge port  158 , and the sub PCB  42  may be disposed above the right discharge port  159 . 
     However, when there is only one PCB installed in the entrance refrigerator  10 , the PCB may be disposed above only one of the left discharge port  158  and the right discharge port  159 . 
     In addition, when there is a plurality of PCBs, the PCBs need not be right above the left discharge port  158  and the right discharge port  159 . In other words, the PCBs may be appropriately disposed in a space between the suction plate  17  and the left surface portion  154 , and a space between the suction plate  17  and the right surface portion  155 . 
     In addition, the PCBs  41  and  42  may be fixed at positions spaced apart by a predetermined interval upward from the bottom portion  151  of the housing  15  in order to prevent the left discharge port  158  and the right discharge port  159  from being blocked by the PCBs  41  and  42 . 
     As one method, a fastening screw passing through the edge of the PCB is inserted into and fixed to the bottom surface of the cabinet  11 . The insertion depth of the fastening screw may be adjusted to allow the PCB to be disposed in a space between the bottom surface of the cabinet  11  and the bottom portion  151  of the housing  15 . 
     A left heat dissipation hole  154   a  and a right heat dissipation hole  155   a  may be formed in the left surface portion  154  and the right surface portion  155 , respectively, in order to quickly discharge, to the outside of the housing  15 , the indoor air absorbing heat while passing over and/or through the PCBs  41  and  42 . 
     The indoor air flowing in the horizontal direction while cooling the PCBs may be discharged through the left and right heat dissipation holes  154   a  and  155   a , and the flow resistance may be minimized because there is no switching of the air flow direction in the flow passage. 
     A portion of the air absorbing heat from the PCBs may be discharged into the room through the left discharge port  158  and the right discharge port  159  by switching the flow passage. Another portion of the air absorbing heat from the PCBs may be discharged through the left heat dissipation hole  154   a  and the right heat dissipation hole  155   a.    
     In order to ensure that the indoor air forcibly flowing inside the housing  15  due to the heat dissipation fan  36  is concentrated toward the PCBs  41  and  42 , the flow guide plate  150  may be provided inside the housing  15 . 
     The flow guide plate  150  may extend by a predetermined height and a predetermined length near four corners of the suction plate  17 . 
     The flow guide plate  150  may be symmetrically formed with respect to a center line L 1  that bisects the housing  15  in a front-to-back direction. 
     The flow guide plate  150  may be symmetrically formed with respect to a center line L 2  that bisects the housing  15  in a left-to-right direction. 
     The flow guide plate  150  may include an inner flow guide plate  150   a  located at a point spaced apart from the center line L 1  by a predetermined interval, and an outer flow guide plate  150   b  located at a point farther away from the center line L 1  than the inner flow guide plate  150   a.    
     The inner flow guide plate  150   a  may extend in a lateral direction of the housing  15  from a point close to the edge of the suction plate  17 . The inner flow guide plate  150   a  may be slanted in a direction closer to the center line L 1  toward the lateral direction of the housing  15 . The inner flow guide plate  150   a  may extend straight, or may extend to be bent once or more, or may be smoothly rounded with a predetermined curvature. 
     The outer flow guide plate  150   b  may also extend in the lateral direction of the housing  15  from the point close to the edge of the suction plate  17 . In addition, the outer flow guide plate  150   b  may also be slanted in a direction closer to the center line L 1 . In addition, like the inner flow guide plate  150   a , the outer flow guide plate  150   b  may also extend straight, or may be bent a plurality of times, or may be smoothly rounded. 
     As the inner flow guide plate  150   a  extends obliquely in a direction closer to the center line L 1 , the air forcedly flowing due to the heat dissipation fan  36  concentrates on and flows toward the center of the PCBs. Therefore, it is advantageous to install a PCB in which electrical components generating a large amount of heat are installed in the center of the PCB. 
     According to the arrangement of the electrical components mounted on the PCB, the extension direction of the flow guide plate  150  may be appropriately adjusted. That is, by allowing a relatively large amount of air to flow toward the electrical component generating a large amount of heat, the cooling rate of the electric component mounted on the PCB may be maintained uniformly over the entire PCB. 
       FIG. 18  is a bottom perspective view of the housing  15  in which a flow separation plate is attached to a bottom of the housing  15 , according to an embodiment. 
     Referring to  FIG. 18 , the flow separation plate  45  may be attached to the bottom of the housing  15  in order to minimize or prevent mixing of the indoor air introduced into the housing  15  through the suction plate  17  and the indoor air discharged into the room through the left discharge port  158  and the right discharge port  159 . 
     The flow separation plate  45  may be disposed at the left edge region and the right edge region of the suction plate  17 , and may extend from the bottom surface of the housing  15  by a predetermined distance. 
     The flow separation plate  45  may extend in the front-to-rear direction of the housing  15  by a length corresponding to the lengths of the left and right surfaces of the suction plate  17 . The flow separation plate  45  is preferably formed to be equal to or longer than the length of the side surface portions of the suction plate  17 . 
     The flow separation plate  45  may minimize an occurrence in which high-temperature indoor air discharged from the left discharge port  158  and the right discharge port  159  is re-introduced through the suction plate  17 . 
     The indoor air discharged through the left discharge port  158  and the right discharge port  159  absorbs heat from the heat sink  34  of the cold air supply device  30  and the PCBs  41  and  42 , and thus, the temperature of the indoor air increases. As such, when the air having the increased temperature is re-introduced into the housing  15  through the suction plate  17 , the heat dissipation capability of the heat sink  34  and the PCBs  41  and  42  may be significantly reduced. In order to minimize such an occurrence, the flow separation plate  45  is provided on the bottom of the housing  15 . 
       FIG. 19  is a bottom perspective view of a housing  15  provided with a flow separation plate  45 , according to another embodiment. 
     Referring to  FIG. 19 , in the housing  15  according to the present embodiment, the flow separation plate  45  is disposed at points adjacent to side edges of the left discharge port  158  and the right discharge port  159 . 
     As proposed in the present embodiment, the flow separation plate  45  is installed at a point closer to the left discharge port  158  and the right discharge port  159  than the suction plate  17 , thereby minimizing a flow resistance of the indoor air introduced through the suction plate  17 . 
     The flow separation plates  45  proposed in  FIGS. 18 and 19  may be disposed in positions facing each other, so as to extend downward in a direction away from each other. As such, since the distance between the lower ends of the flow separation plates  45  facing each other is longer than the distance between the upper ends thereof, the flow resistance of the air introduced into the suction plate  17  may be minimized and the suction flow rate may be increased. 
     Furthermore, since the indoor air discharged through the left discharge port  158  and the right discharge port  159  is discharged downward in a direction away from each other, the possibility of re-introduction of the discharged air through the suction plate  17  is significantly reduced. 
       FIG. 20  is a flowchart for describing a heat dissipation fan driving algorithm of a cold air supply device  30  for cooling the PCBs  41  and  42 . 
     Referring to  FIG. 20 , the heat dissipation fan  36  of the cold air supply device  30  must be driven in order to cool the PCBs  41  and  42  installed in the entrance refrigerator  10 . 
     In detail, power consumption is inevitable in order to drive the heat dissipation fan  36 . Therefore, there is a need to consider the best method for effectively cooling the PCBs  41  and  42  while minimizing the power consumption. 
     To this end, the temperature of the space in which the housing  15  of the entrance refrigerator  10  is installed (hereinafter, defined as an outside temperature) and the temperature of the storage compartment  111  of the entrance refrigerator  10  are preferably considered together. 
     First, a controller  41   a  of the entrance refrigerator  10  determines whether a current cooling mode is turned on (S 110 ). For reference, the controller  41   a  may be understood as meaning a microcontroller component installed on one of the PCBs  41  and  42 . 
     The cooling mode may be defined as an operation mode for maintaining the storage compartment  111  at a refrigerating temperature or a freezing temperature. 
     When the cooling mode is on and the cold air supply device  30  is being operated, a detecting of an outside temperature TR is performed (S 130 ). 
     However, when a cooling mode on command is inputted and the cold air supply device  30  is determined to be in a non-driven state, the controller  41   a  drives the cold air supply device  30  by supplying power to the cold air supply device  30  (S 120 ). The driving of the cold air supply device  30  may be understood as power being supplied to the thermoelectric element  31 , and power being supplied to the heat absorption fan  33  and the heat dissipation fan  36  to cause them to rotate. 
     The outside temperature may be understood as including one of the indoor temperature or the outdoor temperature. For example, when the air introduced into the housing  15  by the heat dissipation fan  36  is indoor air, the outside temperature may be understood as referring to the indoor temperature, and when the air introduced into the housing  15  is outdoor air, the outside temperature may be understood as referring to the outdoor temperature. 
     The controller  41   a  determines whether the detected outside temperature TR is lower than a set temperature TS (S 140 ). When it is determined that the outside temperature TR is lower than the set temperature TS, the heat dissipation fan  36  is controlled to rotate at an intermediate speed (S 150 ). 
     The set temperature TS may be 35° C. corresponding to a summer daytime temperature, but the present disclosure is not limited thereto. When the outside temperature TR is lower than the set temperature TS, the temperature of the air suctioned by the heat dissipation fan  36  is not excessively high. Therefore, since the suctioned outside air is unlikely to adversely affect the cooling of the PCBs  41  and  42 , the rotational speed of the heat dissipation fan is maintained at an intermediate level. 
     However, when the outside temperature TR is higher than the set temperature TS, it is necessary to adjust the rotational speed of the heat dissipation fan  36  in consideration of the current temperature TC of the storage compartment. 
     In detail, the controller  41   a  determines whether the current temperature TC of the storage compartment  111  is maintained below a satisfactory temperature (S 141 ). 
     When the temperature of the storage compartment  111  is maintained below the satisfactory temperature, it can be understood as a situation in which the cold air supply device  30  does not need to be driven, or may be driven with low output if driven. Therefore, in order to cool the PCBs  41  and  42 , the controller  41   a  may control the heat dissipation fan  36  to rotate at a low speed (S 142 ). By doing so, the power consumption for driving the cold air supply device  30  may be reduced, and the PCBs  41  and  42  may be cooled. 
     In contrast, when the temperature of the storage compartment  111  is higher than the satisfactory temperature, that is, an unsatisfactory temperature, it may be understood as a situation in which the output of the cold air supply device  30  must be increased for cooling the storage compartment  111  and at the same time the PCBs  41  and  42  must be cooled. 
     When the amount of current supplied to the thermoelectric element  31  is increased in order to lower the temperature of the storage compartment  111  to the satisfactory temperature, the surface temperature of the heat sink  34  increases. Therefore, the temperature of the air passing through the heat sink  34  becomes high, and the cooling performance of the PCBs  41  and  42  may be degraded. 
     Therefore, in order to prevent the cooling performance of the PCBs  41  and  42  from being degraded, the heat dissipation fan  36  is rotated at a high speed to increase the amount of air flowing per unit time (S 143 ). 
     When the amount of the air flowing per unit time increases, the temperature increase amount of the air passing through the heat sink  34  is lowered. Therefore, the ability of the air passing through the heat sink  34  to cool the PCBs  41  and  42  is not degraded. 
     When the temperature of the storage compartment  111  is lowered below the satisfactory temperature while the heat dissipation fan  36  is rotated at a high speed, the rotational speed of the heat dissipation fan  36  may be switched to a low speed in order to minimize power consumption. 
     As described above, the heat dissipation fan rotation algorithm for cooling the PCBs  41  and  42  may be repeatedly performed unless the power of the entrance refrigerator  10  is turned off (S 160 ). 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present disclosure. 
     Thus, the technical spirit of the present disclosure is not limited to the foregoing embodiment. 
     Therefore, the scope of the present disclosure is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present disclosure.