Patent Description:
Generally, a refrigerator is an apparatus for freeze or refrigerate foods by maintaining a temperature of a storage area provided therein at a predetermined temperature by using a freezing cycle configured of a compressor, a condenser, an expansion valve and an evaporator. Therefore, the refrigerator includes a storage area, for example, a freezer compartment and a refrigerator compartment, and its type is classified in accordance with positions of the freezer compartment and the refrigerator compartment. For example, the refrigerator may be classified into a top mount type having a freezer compartment mounted on a top of a refrigerator compartment, a bottom freezer type having a freezer compartment mounted below a refrigerator compartment, and a side by side type having freezer and refrigerator compartments arranged side by side.

The freezer compartment and the refrigerator compartment are provided inside a cabinet forming external appearance, and each of them may selectively be opened and closed by a freezer door and a refrigerator door. Some refrigerators include a user input panel provided on a door front surface. The panel may be provided to allow a user to apply a touch input thereto. This may be referred to as an interactive touch input panel. The user may select or change various functions of the refrigerator through the interactive touch input panel. Some refrigerators, particularly, a show case refrigerator used in a conveniences store may allow a user to see the inside of the refrigerator even without opening a door because the door is comprised of glass. However, since a refrigerator for home use includes an opaque freezer door and an opaque refrigerator door, it is general that the user may see the inside of the refrigerator by opening the freezer door and the refrigerator door.

In some refrigerator for home use, a user may see the inside of the refrigerator even without opening a door of the refrigerator. Therefore, cool air loss caused by frequently opening or closing the door may be avoided.

In this refrigerator, it is general that the door includes a panel assembly through which a user may see the inside of the refrigerator, and a frame assembly for supporting the panel assembly.

Meanwhile, the freezer compartment and the refrigerator compartment are provided inside a cabinet constituting external appearance of the refrigerator, and selectively opened or closed by a freezing door and a refrigerator door (hereinafter, referred to as "door for refrigerator" or "door" as a generic term. Since the refrigerator compartment or the freezer compartment are selectively sealed by the door for the refrigerator, the door should have predetermined insulation performance. To this end, a predetermined space is formed by a frame structure body constituting external appearance of the door to have a predetermined rigidity, the space is generally foamed and filled with a thermal insulator such as polyurethane to make a door. Since the frame structure body is a thin plate member, a foaming space determined by the frame structure body becomes a size of the door, that is, "upper and lower width of the door x left add right width of the door x depth of the door (front and rear direction of the door)", and this space becomes a foaming space and a foaming path, which should be filled with a thermal insulator.

In this door, since a size of the door becomes a foaming space, and the foaming space becomes a foaming path, the foaming path is relatively great. Therefore, a foaming injection hole is arranged at a center, approximately, of a rear surface (exactly, frame structure body) of the door. The temporary assembly door is arranged horizontally to allow the front surface of the temporarily assembled door toward the ground surface during foaming of the thermal insulator, and then the foaming agent which is the thermal insulator is injected through the foaming injection hole provided at the center of the rear surface of the temporary assembly door.

Meanwhile, since the aforementioned door for a general refrigerator is opaque, a user may see the inside of the refrigerator by opening the freezer door and the refrigerator door. Recently, a refrigerator for allowing a user to see the inside thereof even without opening a door thereof has been suggested to reduce door opening or closing of thereof and thus avoid cool air loss caused by frequently opening or closing of the door.

In this refrigerator, it is general that the door includes a panel assembly comprised of glass through which the user may see the inside of the refrigerator, and a frame assembly for supporting the panel assembly. Of course, it is general that the door includes a panel assembly having a touch input assembly and a frame assembly for supporting the panel assembly.

However, in the door for the refrigerator, the foaming space and the foaming path becomes a space defined by a portion except the panel assembly from the entire door, that is, an outer edge of the frame assembly and the panel assembly. Therefore, the door has a relatively smaller foaming space and foaming path than those of a general door, a problem may occur during foaming of the thermal insulator. That is, since foaming resistance is great during foaming of the thermal insulator, a problem may occur in that the foaming space may not be fully filled with the thermal insulator. Also, the foaming agent type thermal insulator may be swollen to leak into the foaming injection hole or the panel assembly or the foaming agent may flow backward to the foaming injection hole. Therefore, a solution for solving this problem is required.

This problem of the door may occur equally or similarly to a door of a home appliance, which requires insulation, as well as a door of a refrigerator.

<CIT> relates to a refrigerator including a cabinet and a refrigerator door. The refrigerator door opens and closes the storage compartment of the cabinet. The refrigerator door includes: an outer case; a door liner; an ice maker; an ice bin; and a dispenser housing. The door liner is combined with the outer case and forms the ice compartment.

<CIT> and <CIT> are also related prior art documents.

The invention is specified by the independent claim <NUM>.

According to the present invention, a refrigerator according to claim <NUM> comprises a cabinet constituting appearance of the refrigerator; a main door rotatably coupled to the cabinet; and a sub door rotatably coupled to the main door, wherein the sub door includes a panel assembly; and a frame assembly having an opening connected with an edge of the panel assembly to support the panel assembly, and making a foaming space for receiving a thermal insulator between edges of the frame assembly and the panel assembly, wherein a foaming injection hole through which the thermal insulator is injected is provided on at least one of ends of an upper surface, or a lower surface of the frame assembly.

The rear frame may be provided with a gasket mounting groove on which a gasket is mounted, and the gasket mounting groove maybe provided with vent holes formed to discharge out the air inside the foaming space during foaming.

The gasket is mounted on the gasket mounting groove, and thus the gasket mounting groove is covered by the gasket. Therefore, the vent holes formed in the gasket mounting groove are covered by the gasket. Therefore, since the vent holes are not exposed to the outside, esthetic appearance of the door is not damaged.

Also, the foaming injection hole may be covered after foaming. For example, a cover coupled with the lower frame may be provided. That is, if foaming is completed, the cover is coupled with the lower frame, whereby the foaming injection hole may be covered.

First of all, according to the present invention, since foaming resistance may be reduced when a temporarily assembled door is foamed with a thermal insulator, the thermal insulator may be prevented from being less filled in the frame assembly.

Secondly, according to the present invention, since foaming resistance may be reduced when a temporarily assembled door is foamed with a thermal insulator, the thermal insulator which is a foaming agent may be prevented from being leaked to the foaming injection hole or the panel assembly while being swollen. Also, the thermal insulator which is the foaming agent may be prevented from flowing backward to the foaming injection hole.

Hereinafter, the preferred embodiment of the present invention and examples not being part of the present invention will be described with reference to the accompanying drawings. <FIG> shows an embodiment useful for understanding the invention, whereas <FIG> show examples not being part of the present invention.

Hereinafter, for convenience of description, a bottom freezer type refrigerator will be described. Of course, the present invention is not limited to the bottom freezer type refrigerator, and may be applied to a top mount type refrigerator, a side by side type refrigerator, etc. Also, a refrigerator according to claim <NUM> provided with a refrigerator door having a main door and a sub door <NUM> will be described exemplarily.

First of all, a whole configuration of an embodiment useful for understanding the invention of a refrigerator will be described with reference to <FIG>.

A refrigerator compartment is provided at an upper portion of a cabinet <NUM>, and a freezer compartment is provided at a lower portion of the cabinet <NUM>. Doors <NUM>, <NUM>, <NUM> and <NUM> are rotatably installed at upper and lower portions of the cabinet <NUM> to open or close the refrigerator compartment and the freezer compartment. Although two doors <NUM>, <NUM>, <NUM> and <NUM> for respectively opening or closing the refrigerator compartment and the freezer compartment are shown in this embodiment, one door may be used without limitation to this embodiment.

According to this embodiment, the right door for the refrigerator compartment includes a main door <NUM> rotatably coupled to the cabinet <NUM>, and a sub door <NUM> rotatably coupled to the main door <NUM>. Since the main door <NUM> is provided with another side storage space such as a basket, a user may approach storage goods kept in the side storage space by opening the sub door <NUM> only without opening the main door <NUM>.

The sub door <NUM> according to this embodiment includes a panel assembly <NUM> through which a user may see from the outside of the refrigerator, and a frame assembly <NUM> for supporting the panel assembly <NUM>. Preferably, the panel assembly <NUM> has predetermined insulation performance by using insulation glass, etc., and the frame assembly <NUM> has predetermined insulation performance. To avoid dew formation at a connection portion <NUM> between the panel assembly <NUM> and the frame assembly <NUM>, it is preferable that a heating element <NUM> is provided at the connection portion between the panel assembly <NUM> and the frame assembly <NUM> (detailed structure of panel assembly, frame assembly and heating element will be described later).

<FIG> shows an example not being part of the present invention. The sub door <NUM> is only one example of the door having the panel assembly <NUM>. Therefore, the sub door <NUM> will be referred to as "door" for convenience of description except that the sub door <NUM> should be provided as a special door. <FIG> briefly illustrates the door <NUM> having the panel assembly <NUM>. Also, the rear surface of the door <NUM> is shown as an upper portion.

As described above, the door <NUM> includes a panel assembly <NUM>, a frame assembly <NUM> for supporting the panel assembly <NUM>, and a thermal insulator <NUM> defined by the frame assembly and foamed in a foaming space. Preferably, the panel assembly <NUM> is, but not limited to, approximately rectangular shape to correspond to the shape of the door. Preferably, the frame assembly <NUM> supports an edge 11a of the panel assembly <NUM>. For example, the frame assembly <NUM> defines a foaming space having an opening <NUM>, and the panel assembly <NUM> is preferably connected to the opening <NUM> (see <FIG>).

Meanwhile, in case of a door having no panel assembly <NUM>, a foaming space becomes a size of the door, that is, "left and right width DW2 of the door x upper and lower width DW2 of the door x depth DH of the door". Also, the foaming space briefly becomes a foaming path. However, in case of the door <NUM> having the panel assembly, a space substantially made by the frame assembly <NUM> becomes a foaming space. The foaming space becomes a space excluding the size of the panel assembly <NUM> from the size of the door <NUM>. The size of the panel assembly <NUM> becomes "left and right width GW1 of the panel assembly x upper and lower width GW2 of the panel assembly x depth GH of the panel assembly". Also, since the frame assembly <NUM> is connected to the edge 11a of the panel assembly <NUM>, a space made between the edge 11a of the panel assembly <NUM> and an edge 20a of the frame assembly <NUM> becomes a foaming space. Therefore, a left and right width FW1 of the frame assembly <NUM> becomes a difference between the left and right width DW1 of the door <NUM> and a left and right width GW1 of the panel assembly <NUM>, and an upper and lower width FW2 of the frame assembly <NUM> becomes a difference between the upper and lower width DW2 of the door <NUM> and an upper and lower width GW2 of the panel assembly <NUM>. Although the depth of the frame assembly <NUM> may be different from the depth DH of the door <NUM>, it is preferable that the depth of the frame assembly <NUM> is approximately the same as the depth DH of the door <NUM>. Also, it is preferable that the depth of the frame assembly <NUM> is the same as or greater than the depth GH of the panel assembly <NUM>.

Generally, the size of the door <NUM> is previously determined in accordance with the refrigerator, and it is preferable that the size of the panel assembly <NUM> is great if possible. This is because that the user may easily see the inside of the refrigerator through the panel assembly <NUM> if the size of the panel assembly <NUM> is great. Therefore, if requirements of the door such as rigidity and insulation are within a satisfactory range, the size of the panel assembly <NUM>, particularly the left and right width GW1 and the upper and lower width GW2 are close to the left and right width FW1 and the upper and lower width DW2 of the door, whereby it is preferable that the left and right width FW1 and the upper and lower width DW2 of the frame assembly <NUM> are small. Therefore, it is preferable that the difference between the upper and lower width DW2 of the door <NUM> and the upper and low width GW2 of the panel assembly <NUM> and the difference between the left and right width DW1 of the door <NUM> and the left and right width GW1 of the panel assembly <NUM> are relatively small.

That is, it is preferable that an interval between the edge 11a of the panel assembly <NUM> and the edge 20a of the frame assembly <NUM>, that is, the widths FW1 and FW2 of the frame assembly <NUM> are relatively narrow. If the size of the panel assembly <NUM> is maximized while another design condition of the door <NUM> is being satisfied, it is preferable that the widths FW1 and FW2 of the frame assembly <NUM> are minimized and the depth DH of the frame assembly <NUM> is minimized. This means that the foaming path becomes smaller than the width of the foaming path allowable in the thermal insulator foaming method of the related art. To this end, the depth DH and the widths FW1 and FW2 of the frame assembly <NUM> may be about <NUM> or less, for example.

Meanwhile, the foaming space where the thermal insulator <NUM> is foamed becomes a space mainly made by the frame assembly <NUM>. However, as described above, it is preferable that the widths FW1 and FW2 of the frame assembly <NUM> are relatively narrow in view of the properties of the frame assembly <NUM>. Therefore, in case of the panel assembly door <NUM>, the foaming space and the foaming path are relatively smaller than those of the door having no panel assembly. Therefore, in accordance with the related art, if the foaming injection hole (for example, A1) is provided on a rear surface of the frame assembly <NUM> and the thermal insulator <NUM> is injected through the foaming injection hole A1, a problem may occur in foaming performance. This is because that the foaming interval of the door <NUM> is narrower than the foaming interval allowable in the foaming method of the related art and thus foaming resistance may be increased to cause a problem in foaming performance.

That is, since the depth DH and the width FW1 of the frame assembly <NUM> are small, foaming resistance is great and thus a filling time is increased and the foaming agent may not be filled fully. Also, the foaming agent may be leaked to the foaming injection hole A1 or the panel assembly <NUM>. Therefore, it is preferable that foaming injection holes B1, B2, B3, B4 and B5 are arranged at predetermined positions corresponding to at least one of a left side, a right side, an upper surface and a lower surface not front and rear surfaces of the frame assembly <NUM>.

The foaming injection holes B1, B2, B3, B4 and B5 of the door <NUM> for the refrigerator will now be described in detail.

As described above, it is preferable that the foaming injection holes B1, B3, B3, B4 and B5 are provided on at least one of the left side, the right side, the upper surface and the lower surface (hereinafter, comprehensively referred to as "side" except that the respective sides of the frame assembly <NUM> should be categorized specially from one another) of the frame assembly <NUM>. (the foaming injection holes at the left side and the lower surface are shown in <FIG>). Also, it is more preferable that the foaming injection holes B2, B3, B4 and B5 are provided on ends of the upper surface, the lower surface, the left side and the right side of the frame assembly <NUM>. This is because that if the foaming injection hole B1 is located at the center of the side of the frame assembly <NUM>, the distance FW1 between the panel assembly <NUM> and the foaming injection hole B1 is short, and thus foaming is slowly performed in a length direction L (orthogonal direction of the foaming direction). Also, in this case, the foaming agent may be leaked along the direction of the panel assembly <NUM>. Therefore, it is preferable that the foaming injection holes B2, B3, B4 and B5 are located toward the end of the frame assembly <NUM> instead of the center of the frame assembly <NUM>.

Meanwhile, as described above, the foaming injection holes B2, B3, B4 and B5 may be located at the side of the frame assembly <NUM>, that is, ends of the left side, the right side, the upper surface and the lower surface. However, in case of the foaming injection holes B2 and B3 (the foaming injection hole of the left side is only shown in <FIG>) located at the right side and the left side of the frame assembly <NUM>, although the thermal insulator may be foamed without relative foaming resistance, the foaming injection holes B2 and B3 are exposed after foaming, whereby it is not good in view of esthetic appearance. This is because that the right side and the left side of the frame assembly <NUM> constitute external appearance of the door <NUM>, and the foaming injection holes B2 and B3 may be seen to a user when the door <NUM> is opened or closed. Also, a hinge structure (not shown) for connecting the door <NUM> to the cabinet of the refrigerator to open or close the door <NUM> is coupled to upper and lower ends of the right side or the left side of the frame assembly <NUM>. Therefore, if the foaming injection holes B2 and B3 are located at the ends of the right side and the left side of the frame assembly <NUM>, the hinge structure may be foaming resistance during foaming of the thermal insulator. Therefore, it is more preferable that the foaming injection holes B4 and B5 (the foaming injection hole of the lower surface is only shown in <FIG>) are provided at the ends of the upper surface and the lower surface instead of the ends of the left side and the right side of the frame assembly <NUM>.

Meanwhile, as described above, if the foaming injection holes B4 and B5 are provided at the ends of the upper surface and the lower surface of the frame assembly <NUM>, there is no problem in foaming task of the thermal insulator. However, parts such as a sensor, a PCB, and a magnet are installed at the end of the upper surface of the frame assembly <NUM>. Therefore, if the foaming injection hole (not shown) is located at the end of the upper surface of the frame assembly <NUM>, the position of the foaming injection hole should be selected to avoid the above parts, and the above parts may be foaming resistance. Also, the foaming injection hole located at the end of the upper surface of the frame assembly <NUM> may be exposed to the outside during opening of the door. Particularly, in case of the door installed at the lower portion of the refrigerator, if the door is opened, the foaming injection hole is seen to a user, whereby it is not good in view of esthetic appearance. Therefore, it is more preferable that the foaming injection holes B4 and B5 are located at the end of the lower surface of the frame assembly <NUM>.

Meanwhile, one foaming injection hole B4 or B5 may be provided at one end of the lower surface of the frame assembly <NUM>, or two foaming injection holes B4 and B5 may respectively be provided at both ends. If one foaming injection hole is provided, it is preferable that a position favorable for obtaining foaming quality is selected. For example, in the same manner as the embodiment shown in <FIG>, if an indentation <NUM> that serves as a handle is provided at one side of the frame assembly <NUM>, it is preferable that the foaming injection hole B4 is selected at the end of an opposite portion. This is because that the foaming injection hole B5 may be partially overlapped with the edge of the frame assembly <NUM> if the foaming injection hole B5 at the portion where the indentation <NUM> serving as a handle is provided is selected. Therefore, since a part of the foaming agent is in contact with the edge portion of the frame assembly <NUM>, the foaming agent may flow backward. On the other hand, if the foaming injection hole B4 at the portion where the indentation <NUM> is not formed is selected, since the foaming injection hole B4 is not partially overlapped with the frame assembly <NUM>, the foaming agent may be prevented from flowing backward (see <FIG>). Of course, if there is no problem as the indentation <NUM> is not provided in accordance with the structure of the door, the foaming injection hole may be selected regardless of the left and right sides.

Meanwhile, as described above, the foaming agents B4 and B5 may respectively be provided at both ends of the frame assembly <NUM>. Even in this case, in the same manner as the example not being part of the present invention shown in <FIG>, if the indentation <NUM> serving as a handle at one side of the frame assembly <NUM> is provided, the foaming agent flown to the foaming injection hole B5 at the portion where the indentation <NUM> is provided may flow backward. To avoid this, it is preferable that the width of the lower surface of the frame assembly <NUM> where the foaming injection holes B4 and B5 are provided is greater than the widths of the left side portion, the right side portion and the upper surface portion. If the width of the left side portion, the right side portion and the upper surface portion of the frame assembly <NUM> is smaller than <NUM>, it is preferable that the width of the lower surface portion is greater than <NUM>. For example, if the width of the left side portion, the right side portion and the upper surface portion of the frame assembly <NUM> is <NUM>, it is preferable that the width of the lower surface portion is <NUM>. In this case, since the foaming agent flown to the foaming injection hole B5 is relatively great and may be guided to the portion where foaming resistance is small, leakage of the foaming agent may be avoided.

Referring to <FIG> and <FIG>, an example not being part of the present invention will be described in detail. The sub door <NUM> is an example of the door having the panel assembly. Therefore, the sub door <NUM> is referred to as a door for convenience of description except that the sub door <NUM> is categorized as a special door in the following description.

It is preferable that the panel assembly <NUM> of the door <NUM> has predetermined insulation performance. Preferably, the panel assembly <NUM> is, but not limited to, approximately rectangular shape to correspond to the shape of the door. Preferably, the frame assembly <NUM> supports the edge of the panel assembly <NUM>, and has predetermined insulation performance. It is preferable that the heating element <NUM> is provided at a portion, that is, connected portion 10a, where the panel assembly <NUM> and the frame assembly <NUM> are mutually connected to each other. That is, the heating element <NUM> may be provided at a predetermined position of the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM>. Also, if the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM> may substantially be heated, the heating element <NUM> may be installed at a predetermined distance from the connected portion 10a.

Each element of the door will be described in detail.

First of all, an example of the panel assembly <NUM> will be described.

As illustrated in <FIG>, the panel assembly <NUM> may include a front panel <NUM>. The front panel <NUM> defines the front surface of the door <NUM>. The front panel <NUM> is made of a transparent material to allow a user to see through the front panel <NUM>. The front panel <NUM> is made of a touch panel to allow a user to control an operation of a home appliance through the touch panel. The front panel <NUM> may be a glass panel. That is, the front panel <NUM> may be a glass panel even if the front panel <NUM> is a transparent panel or a touch panel.

The inner space of the panel assembly, which is defined by the panel assembly <NUM>, may be an insulating space provided at the rear of the front panel <NUM>. For example, as shown in <FIG>, the panel assembly <NUM> may include an intermediate panel <NUM> and a rear panel <NUM> to improve insulation performance. However, without limitation to the example shown in <FIG>, a number of the panel may be varied or another type thermal insulating panel may be provided. Therefore, the panel assembly <NUM> may include the front panel <NUM> and a thermal insulating panel provided at the rear of the front panel. In case of the transparent panel assembly <NUM> shown in <FIG>, the front panel <NUM>, the intermediate panel <NUM> and the rear panel <NUM> may be glass panels, and a space among the panels is sealed by a proper gas. In case of the touch panel assembly <NUM>, an inner space defined by the panel assembly <NUM> may include one or a plurality of sensors, for example, sensors for sensing a touch input applied to the front panel <NUM>, such as a touch sensor and an electromagnetic sensor.

For example, the front panel <NUM> may be formed to be greater than the other portion of the panel assembly <NUM>. In the example shown in <FIG>, the front panel <NUM> is greater than the intermediate panel <NUM> and the rear panel <NUM>. For example, the front panel <NUM> may substantially be the same as the size of the door <NUM>, and may cover the frame assembly <NUM> when viewed at the front of the refrigerator. As described above, since the front panel <NUM> defines a front appearance of the door <NUM>, the front panel <NUM> may have the same size as that of the door and provide very esthetic appearance. The front panel <NUM> may provide appearance of the door seen to a user like that the door is formed as a single panel. To this end, the front panel <NUM> has a peripheral portion or an extension portion (peripheral front panel portion) 16a. The extension portion may be a portion extended from an outer edge of the rear panel <NUM> or the intermediate panel to all directions.

First of all, the panel assembly <NUM> will be described as follows. It is preferable that the panel assembly <NUM> includes two or more panels <NUM>, <NUM> and <NUM> to obtain predetermined insulation performance. The panel may be formed of a glass material. A spacer <NUM> for maintaining intervals among the panels <NUM>, <NUM> and <NUM> is provided at the edges of the panels <NUM>, <NUM> and <NUM>, and it is preferable that the panels <NUM>, <NUM> and <NUM> are coupled to one another by using a sealant <NUM>. That is, the space among the panels may be sealed through the sealant <NUM>.

Preferably, thermal insulation glass having predetermined insulation performance is used as the plurality of panels <NUM> and <NUM>. Of course, two or more thermal insulation glasses may be used. Moreover, low-e glass is preferably used as the thermal insulation glasses <NUM> and <NUM> to shield heat loss caused by radiation. Although a hard low-e glass and a soft low-e glass may be used as the low-e glasses, it is preferable that the soft low-e glass is used to obtain more excellent low-e performance.

Since the front panel <NUM> located at the front of the plurality of panels <NUM>, <NUM> and <NUM> is located at the front of the door <NUM> to form appearance of the door <NUM>, a tempered glass is preferably used to avoid damage. Also, it is preferable that glass (hereinafter, referred to as "discolored glass") through which a user may selectively see the inside of the refrigerator by controlling light transmittance is used as the front panel <NUM>. That is, when a lamp inside the refrigerator is turned off, it is preferable that the front panel <NUM> becomes an opaque state to allow a user not to see the inside of the refrigerator externally. When the lamp inside the refrigerator is turned on, it is preferable that the front panel <NUM> becomes a transparent state to allow a user to see the inside of the refrigerator externally. Also, the front panel <NUM> having a coloring function is not limited to a special glass, and a color glass may be used as the front panel <NUM>, or an opaque coated glass by TI deposition may be used as the front panel <NUM>. Of course, it is preferable that the front panel <NUM> has insulation performance.

Meanwhile, it is preferable that the front panel <NUM> has a size greater than those of the other panels <NUM> and <NUM>, that is, the intermediate panel <NUM> and the rear panel <NUM>. For example, it is preferable that the front panel <NUM> has approximately the same size as that of the door. As described above, since the front panel <NUM> of the panel assembly <NUM> becomes appearance of the door <NUM>, if the size of the front panel <NUM> is the same as that of the door <NUM>, the whole door <NUM> is seen to a user as glass, whereby esthetic appearance is improved. To this end, the front panel <NUM> has an extension portion 16a which becomes a portion extended from the portion corresponding to the edges of the rear panel <NUM> and the intermediate panel <NUM> to a width direction of left and right sides of the door. In this case, since the whole door is seen to a user as a glass, esthetic appearance may be improved.

Although Al or a thermal protection spacer (TPS) may be used as the spacer <NUM>, the TPS is preferably used as the spacer <NUM> to improve insulation performance at the portion where the spacer <NUM> is installed. It is preferable that a moisture absorbent is provided inside the spacer <NUM>.

Meanwhile, a vacuum state may become between the rear panel <NUM> and the intermediate panel <NUM> and between the intermediate panel <NUM> and the front panel <NUM>, or the air or Ar gas may be filled between the rear panel <NUM> and the intermediate panel <NUM> and between the intermediate panel <NUM> and the front panel <NUM>. Since the Ar gas is an inert gas which has insulation performance more excellent than that of the air and can be prevented from being changed by a chemical action, it is preferable that the Ar gas is used instead of the air.

Next, the frame assembly <NUM> will be described in detail.

Preferably, the frame assembly <NUM> has predetermined insulation performance. To this end, the frame assembly <NUM> may include, but not limited to, a portion for supporting the door at a predetermined rigidity for supporting the panel assembly <NUM>, and a portion substantially serving as a thermal insulation function. The frame assembly <NUM> defines a thermal insulation space for receiving a thermal insulator <NUM> having predetermined thermal insulation performance, and is preferably coupled to the panel assembly <NUM>.

Preferably, the frame assembly <NUM> includes, but not limited to, a plurality of parts considering convenience of assembly of the door. First of all, the whole configuration of an example of the frame assembly <NUM> will be described with reference to <FIG>.

The frame assembly <NUM> includes a rear frame <NUM> located at the rear of the door. Also, the frame assembly <NUM> includes side frames <NUM> and <NUM> located at left and right sides of the door, an upper frame <NUM> located on an upper end of the door, and a lower frame <NUM> located at a lower end of the door. For example, the panel assembly <NUM> is transparent, and the rear frame <NUM>, the side frames <NUM> and <NUM>, the upper frame <NUM> and the lower frame <NUM> define a thermal insulation space together with the panel assembly <NUM>. That is, these frames define the thermal insulation space along upper and lower and left and right corners of the panel assembly <NUM> together with the panel assembly <NUM>. In an example of a see-through transparent panel assembly <NUM>, the thermal insulation space may receive the thermal insulator <NUM>. An example of the thermal insulator may include a thermal insulation foam or another material thermal insulator or a thermal insulation gas. The panel assembly <NUM> may be connected to an opening defined by inner corners of the rear frame <NUM>, the side frames <NUM> and <NUM>, the upper frame <NUM> and the lower frame <NUM>. For example, if the panel assembly <NUM> is transparent, side corner portions of the panel assembly <NUM> and the space defined by the frames may be filled with the thermal insulator (see <FIG>). Alternatively, if the panel assembly is a touch panel, a space between the rear panel <NUM> and the intermediate panel <NUM> may be filled with the thermal insulator.

Preferably, the rear frame <NUM> is located at an inner side of the door, and serves to support the whole door. The frames <NUM>, <NUM>, <NUM> and <NUM> are located at upper and lower and left and right portions of the panel assembly <NUM>, and may constitute a part of external appearance of the door. The frames <NUM>, <NUM>, <NUM> and <NUM> prevent distortion of the door from occurring, and preferably serve to prevent dew formation from occurring at the door together with the thermal insulator <NUM>.

The frames <NUM>, <NUM>, <NUM> and <NUM> may constitute a part of external appearance of the door, and for example, may be regarded as a decorative trim that can be seen outside the door.

The rear frame <NUM>, the side frames <NUM> and <NUM> and their mutual relationship will be described with reference to <FIG> again.

Mutual relationship among the panel assembly <NUM>, the rear frame <NUM>, the upper frame <NUM>, and the lower frame <NUM> may have a similar structure. For convenience of description, a basis structure of the rear frame <NUM> and the side frames <NUM> and <NUM> will be described herein, and a more detailed structure thereof will be described in the following example, that is, the example of a modified structure of the frame assembly.

Preferably, the rear frame <NUM> includes a first end <NUM> connected with the panel assembly <NUM>, a second end <NUM> connected to the side frames <NUM> and <NUM>, and a connecting portion <NUM> connecting the first end <NUM> with the second end <NUM>. The first end <NUM> of the rear frame <NUM> is a portion connected to the rear panel <NUM> of the panel assembly <NUM>, and the second end <NUM> is a portion connected to the side frame. It is preferable that the connecting portion <NUM> connecting the first end <NUM> with the second end <NUM> is approximately parallel with the front surface of the cabinet of the refrigerator. It is preferable that a gasket <NUM> is installed at a predetermined portion <NUM> of the rear frame <NUM> and its inner side is approximately parallel with the portion <NUM> for connecting both ends of the rear frame <NUM>. Meanwhile, it is preferable that the first end <NUM> of the rear frame <NUM> is connected to the rear panel <NUM> to support the rear panel <NUM>. Also, it is more preferable that the first end <NUM> of the rear frame <NUM> is provided to surround the spacer <NUM> which is vulnerable to thermal insulation. In other words, it is preferable that the first end <NUM> is located at the inner side more inwardly than the spacer <NUM> in a radius direction.

The side frame <NUM> (for example, right frame) may include a rear frame connecting portion <NUM> connected with the rear frame <NUM>, and a panel connecting portion <NUM> extended from the rear frame connecting portion <NUM> and adjacent to the outside of the panel assembly <NUM>, preferably the extension portion <NUM>. It is preferable that the panel connecting portion <NUM> of the side frame <NUM> is connected to an end of the extension portion 16a of the front panel <NUM>.

The side frame <NUM> (for example, left frame) may include a rear frame connecting portion <NUM> connected with the rear frame <NUM>, and a panel connecting portion <NUM> extended from the rear frame connecting portion <NUM> and adjacent to the outside of the panel assembly <NUM>, preferably the extension portion <NUM>. The left side frame <NUM> includes an indentation <NUM> indented toward the inner side of the door between the rear frame connecting portion <NUM> and the panel connecting portion <NUM>. The indentation <NUM> may serve as a handle of the door. In this case, it is preferable that a front end of the extension portion 16a connected with the left frame <NUM> in the extension portion 16a of the front panel <NUM> is located at the inner side more inwardly than the rear frame connecting portion <NUM> to make a space into which a hand of a user may be inserted. That is, it is preferable that the width of the extension portion 16a connected with the left frame <NUM> in the extension portion 16a of the front panel <NUM> is smaller than the width of the left frame <NUM>. Also, in this case, the first end of the left frame <NUM>, that is, a transparent window connecting portion <NUM> starts at the position spaced apart from the front end of the extension portion 16a of the front panel <NUM> toward the inner side, is extended to a front end direction and tightly adhered to the inner surface of the extension portion 16a.

Meanwhile, as described above, the rear frame <NUM>, the side frames <NUM> and <NUM>, the upper frame <NUM> and the lower frame <NUM> may define a predetermined space, more particularly, edge portions of the frames <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and the panel assembly <NUM> may define a substantially sealed space. This space is foamed and filled with the thermal insulator <NUM>, for example, polyurethane foam (PU foam), whereby the frame assembly <NUM> has predetermined insulation performance. For example, if the panel assembly <NUM> is not transparent, for example, if the panel assembly <NUM> is a touch panel, this insulation space may be filled with thermal insulators filled in the inner space of the panel assembly <NUM>.

Next, the heating element <NUM> will be described in detail.

As described above, dew formation may occur at the connected portion 10a of the panel assembly <NUM> and the frame assembly <NUM> instead of the panel assembly <NUM> under a specific condition. Therefore, it is preferable that dew formation prevents from occurring at this connected portion than any other portions.

Dew formation may occur at the connected portion between the panel assembly <NUM> and the frame assembly <NUM> because the cool air is concentrated on the connected potion due to relatively vulnerable thermal insulation performance caused by a difference in thermal insulation performance between the panel assembly <NUM> and the frame assembly <NUM>. Also, it is regarded that the portion where the spacer <NUM> of the panel assembly <NUM> is installed in the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM> is particularly vulnerable to thermal insulation performance.

For example, it is preferable that the heating element <NUM> is installed near the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM>, that is, at the connected portion 10a or near the connected portion 10a. For example, as shown in <FIG>, the heating element <NUM> may be installed in an area between the thermal insulator <NUM> and the panel assembly <NUM>. That is, the heating element <NUM> may be provided between the thermal insulator <NUM> and the panel assembly <NUM> along a side of the inner area of the panel assembly <NUM>. It is more preferable that the heating element <NUM> is installed to be close to the front surface of the door <NUM>. This is because that the heating element <NUM> is installed at the position where the front portion of the door <NUM> may be heated because dew formation occurs at the front of the panel assembly <NUM>, that is, at the front portion of the door <NUM>. To this end, for example, as shown in <FIG>, the heating element <NUM> may be provided on a rear surface of the front panel <NUM> of the panel assembly <NUM>. In more detail, the heating element <NUM> may be provided at a position of the rear surface of the front panel <NUM>, which is inclined toward the connected portion 10a.

For example, the heating element <NUM> may be installed at an area of the frame assembly <NUM> connected to the panel assembly <NUM>. In more detail, the heating element <NUM> may be provided on an inner surface or an outer surface of the first end <NUM> of the rear frame <NUM> or may be provided on an inner surface or an outer surface of the panel connecting portion <NUM> of the side frame <NUM>. That is, the heating element <NUM> may be provided on at least one 'B' of the inner surface and the outer surface of the front and rear ends <NUM> and <NUM> of the frame assembly <NUM>. This is because that the portion B is a portion where the front and rear ends of the frame assembly <NUM> are mainly connected to the panel assembly <NUM>.

Meanwhile, as described above, since the spacer <NUM> becomes the portion vulnerable to thermal insulation, the heating element <NUM> may be installed at the portion where the spacer <NUM> is installed, that is, inside the spacer <NUM>, or may be installed in contact with the spacer <NUM> or near the spacer <NUM>. However, if the heating element <NUM> is inside the spacer <NUM>, a moisture absorbent of the spacer <NUM> is detached therefrom, whereby dew condensation may occur inside the panel assembly <NUM>. Also, since the spacer <NUM> is located inside the panel assembly <NUM>, if the heating element <NUM> is installed inside the spacer <NUM> or in contact with the spacer <NUM>, a separate mounting structure is required and a separate line is required. Therefore, considering these matters, it is more preferable that the heating element <NUM> is installed along the edge of the panel assembly <NUM>. If the heating element <NUM> is installed along the edge of the panel assembly <NUM>, it is advantageous that the heating element <NUM> is installed near the spacer <NUM> and at the same time the installation structure is simple.

Meanwhile, as described above, the heating element <NUM> is, but not limited to, preferably installed near the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM>. Even though the heating element <NUM> is a little spaced apart from the connected portion 10a, the heating element <NUM> may be installed at any position on the panel assembly <NUM> if heat is transferred to the connected portion 10a to prevent dew formation from occurring. That is, the position corresponds to the position where the heating element <NUM> transfers heat to the connected portion 10a to prevent condensation from occurring. For example, the heating element <NUM> may be provided on at least one of inner and outer surfaces of the extension portion 16a, that is, the edge of the front panel <NUM> of the panel assembly <NUM>.

Meanwhile, the heating element <NUM> may be provided to heat the connected portion only between the panel assembly <NUM> and the frame assembly <NUM>. Therefore, a preheating type hot wire having less power consumption may be used as the heating element <NUM>. Therefore, it is preferable that the heating element <NUM> may be provided in a hot wire type to surround the edge of the panel assembly <NUM>. That is, it is preferable that the heating element <NUM> is a hot wire and has a shape corresponding to the shape of the edge of the panel assembly <NUM>. If the entire panel assembly is heated, power consumption of about 60W or more is required. However, since the connected portion between the panel assembly <NUM> and the frame assembly <NUM> is heated in this example, power consumption of 7W or less is required. Therefore, power consumption may be lowered to <NUM>/<NUM>.

For example, since the side frames <NUM> and <NUM> are located toward the rear at the edge of the extension portion 16a of the front panel <NUM>, the side frames <NUM> and <NUM> may not be seen to a user when the user looks at the door at the front of the door. Therefore, it is preferable that the front panel <NUM> of the panel assembly <NUM> is the same as the size of the door. Of course, the front panel <NUM> may be formed in a plane shape or a curved shape. Also, the panel connecting portion <NUM> may be connected to the rear surface of the extension portion 16a of the front panel <NUM>. Therefore, the panel connecting portion <NUM> is not seen to the user. Also, the heating element <NUM> may be installed near the connected portion 10a between the panel assembly <NUM> and the frame assembly <NUM>.

It is preferable that an opaque portion <NUM> is provided on an inner surface of the extension portion 16a of the front panel <NUM> to allow the heating element <NUM> not to be seen from the outside of the door and the heating element <NUM> is located on an inner surface of the opaque portion <NUM>. The opaque portion <NUM> may easily be implemented by opaque printing of the inner surface of the front panel <NUM>.

Meanwhile, the heating element <NUM> is preferably attached using an element having thermal conduction property such as Al tape. If the heating element <NUM> is attached by Al tape, the heating element <NUM> may temporarily be fixed during manufacture of the door, and may be prevented from being pushed into the panel assembly <NUM> during foaming of the thermal insulator <NUM>. Also, heat of the heating element <NUM> may effectively be transferred to the periphery by the Al tape.

In more detail, heat generated from the heating element <NUM> may effectively be transferred to the peripheral portion of the front panel <NUM> through the attachment element having thermal conduction property. Also, if the panel assembly <NUM> is see-through, the heating element <NUM> may temporarily be fixed during manufacture of the door through the attachment element such as the Al tape. Therefore, the heating element <NUM> may be prevented from moving during injection of the thermal insulator <NUM>. Of course, the thermal insulator may be prevented from being directly in contact with the heating element <NUM>.

Also, the heating element <NUM> may tightly be fixed to the front panel <NUM> by pressure of the thermal insulator.

Meanwhile, as shown in <FIG>, the side frames <NUM> and <NUM> of the door <NUM> may include heat bridges <NUM> and <NUM>. The heat bridges <NUM> and <NUM> may be provided together with the heating element <NUM>, or may be provided without heating element.

The heat bridges <NUM> and <NUM> transfer external heat transferred from the side frames <NUM> and <NUM> to the inner area of the panel assembly <NUM>. That is, the heat bridges <NUM> and <NUM> may be provided to transfer heat toward the connected portion 10a which is vulnerable to thermal insulation. The cool air inside the refrigerator may be transferred near the connected portion 10a through the spacer <NUM>. Therefore, the heat bridges <NUM> and <NUM> may be heated through heat of the external air.

A method for manufacturing a door according to an example not being part of the present invention will be described with reference to <FIG> and <FIG>.

Foaming quality is affected by a length of a foaming path, a shape of the foaming path, a period change of the foaming path shape, and a filling time. That is, if the foaming path is long or a sectional area of the foaming path is small, foaming resistance is increased and the filling time is also increased in accordance with the increase of the foaming resistance. Therefore, the foaming agent may not be fully filled or material property value such as mechanical strength and thermal insulation performance may not be uniform per foaming period and deviation may occur. Also, deviation of the material property value occurs per foaming period even in the case that there is a period change in the foaming path shape.

Considering this, the method for controlling the door will be described as follows. For convenience, foaming injection holes B4 and B5 are respectively provided at both ends of the lower surface of the frame assembly <NUM>.

First of all, the panel assembly <NUM> and the frame assembly <NUM> are temporarily assembled to make a temporary assembly door <NUM>, and a thermal insulator is injected and foamed through the foaming injection holes B4 and B5 of the temporary assembly door <NUM>, whereby the door is manufactured.

In more detail, the second frames <NUM>, <NUM>, <NUM> and <NUM> are assembled. That is, the upper deco <NUM> and the lower deco <NUM> are fixedly inserted into the left deco <NUM> and the right deco <NUM> to make a temporarily assembled frame assembly <NUM>. Then, the panel assembly <NUM> is temporarily fixed to the temporarily assembled frame assembly <NUM> by a double-sided tape, and the first frame <NUM> is inserted thereto, whereby the temporary assembly door <NUM> is made. It is preferable that the temporary assembly door <NUM> is arranged vertically. That is, it is preferable that the upper surface of the temporary assembly door <NUM> is arranged in a ground direction, whereby the foaming injection holes B4 and B5 provided on the lower surface of the frame assembly <NUM> are arranged on the upper portion of the temporary assembly door <NUM>. In this state, a thermal insulator 60a of a foaming agent state is injected through the foaming injection holes B4 and B5 of the frame assembly <NUM> for a predetermined time.

The temporary assembly door <NUM> is arranged vertically to inject the foaming agent to the foaming injection holes B4 and B5 for the following reasons. Even in the case that the foaming injection holes B4 and B5 are arranged on the upper surface or the lower surface of the temporary assembly door <NUM>, if the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged horizontally, foaming quality may relatively be deteriorated. If the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged horizontally, the foaming agent injected to the foaming injection holes B4 and B5 is expanded while moving along the foaming path from the foaming injection holes B4 and B5. That is, the foaming agent is expanded while moving to a portion GS2 close to the foaming injection holes B4 and B5, and is also expanded when moving to a portion GS1 far away from the foaming injection holes B4 and B5. This is because that the foaming agent moves horizontally without being affected by gravity. Therefore, the foaming agent injected at the portion GS1 farthest away from the foaming injection holes B4 and B5 is finally expanded and coagulated, and a gas trap occurs there. Also, the foaming agent injected even at the portion GS2 close to the foaming injection holes B4 and B5 is expanded and coagulated, whereby a gas trap occurs. Therefore, if the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged horizontally, the foaming path is narrow and the gas trap occurs at two portions by means of horizontal movement of the foaming agent, whereby two air vent holes are required. Also, incomplete filling of the foaming agent may occur due to the gas trap and path resistance.

However, even in the case that the foaming injection holes B4 and B5 are arranged on the upper surface or the lower surface of the temporary assembly door <NUM>, if the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged vertically, occurrence of the gas trap may be minimized and foaming quality may be improved. A foaming procedure corresponding to the case where the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged vertically will be described as follows.

The foaming agent injected to the two foaming injection holes B4 and B5 moves to a half of all of the foaming paths. Also, the foaming agent 60a injected from the respective foaming injection holes B4 and B5 moves along gravity and is collected on the lower surface LS. The foaming agent collected on the lower surface LS is expanded while upwardly moving along a vertical path f1. The foaming agent moving to the upper portion is expanded while moving along a horizontal path f2 and finally is fully filled in the foaming space. If the foamed thermal insulator is coagulated, the manufacture of the door is finally completed. Therefore, if the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged vertically, the gas trap may occur at only the portion GS2 where foaming is finally completed. As a result, one air vent hole is required, and incomplete filling of the foaming agent may be avoided effectively.

Moreover, if the foaming agent is injected in a state that the temporary assembly door <NUM> is arranged vertically in the same manner as the embodiment according to the present invention, the following advantages are obtained. That is, if a left and right width FW1 of the frame assembly <NUM> is relatively small, for example, <NUM> or less, the foaming agent injected to the foaming injection holes B4 and B5 stained in the inner side of the frame assembly <NUM> while moving to the lower portion, whereby it is predicted that there may be a problem in foaming quality. However, unlike the prediction, even though the injected foaming agent is partially stained in the inner side of the frame assembly <NUM>, there is no problem in foaming quality. In this case, the foaming agent moving to the bottom of the frame assembly without being stained in the inner side of the frame assembly <NUM> and the foaming agent stained in the inner side of the frame assembly <NUM> are together foamed to enable uniform foaming. That is, if the foaming agent is foamed vertically, a part of the foaming agent is stained in the inner side of the frame assembly <NUM> using resistance caused by viscosity of the foaming agent, and the other of the foaming agent reaches the lower surface LS, whereby it is advantageous that foaming is simultaneously performed at the vertical portion and the lower portion to enable uniform foaming.

Also, if the two foaming injection holes B4 and B5 are used like this example, the foaming path is substantially reduced to a half and the shape change of the foaming path is reduced to a half. Also, the filling time is reduced. Therefore, incomplete filling of the foaming agent may be avoided, and deviation of the material property value such as thermal insulation performance and coupling rigidity may be minimized.

Meanwhile, although the foaming injection hole B4 is located at both ends of the lower surface of the frame assembly <NUM> in the aforementioned example, one foaming injection hole may be provided. If one foaming injection hole is provided, that is, if one foaming injection hole on the upper surface of the frame assembly <NUM> is provided, since the foaming path becomes the space formed by the frame assembly, the foaming path is relatively long and filling time is relatively long. Also, sides of the frame assembly <NUM>, that is, left side, right side, upper surface and lower surface have similar sectional shapes, which are not completely the same as one another. This is because that the parts installed in the corresponding space are different from one another. For example, structures of the space where electronic units are installed, the space where hinge members are coupled, and the portion coupled to the main door cannot be completely the same as one another. Therefore, although the panel assembly <NUM> and the frame assembly <NUM> are provided, their detailed shapes and dimensions may be different from each other (see sectional views of left side, right side, upper surface and lower surface of <FIG>). Therefore, as described above, if one foaming injection hole is provided on the lower surface of the frame assembly <NUM>, it is preferable to select a position where foaming quality can be maximized. For example, as shown in <FIG>, if a handle is provided at one side of the frame assembly <NUM>, it is preferable to select the foaming injection hole B4 of the end of the opposite side.

The door will be described with reference to <FIG>. In case of the main door <NUM>, there is no panel assembly <NUM>. In view of foaming, the substantial structure of the main door <NUM> is the same as the frame assembly <NUM> of the sub door <NUM>. The main door <NUM> has a center portion <NUM> which is opened, and has an edge surrounding the center portion <NUM>, that is, a support portion <NUM>, and a thermal insulator is received in the space defined by the support portion <NUM>. The support portion <NUM> has predetermined rigidity to allow the main door <NUM> to be rotatably connected with the cabinet <NUM> of the refrigerator, and has predetermined thermal insulation performance to allow the cool air inside the refrigerator not to leak out. Since the support portion <NUM> of the main door <NUM> is opened, the support portion <NUM> has a width which is relatively small. Therefore, the foaming path may be small and foaming resistance may be great. In this respect, the foaming injection hole to which the thermal insulator is injected is provided on at least one of the ends of the upper surface, the lower surface, the left side and the right side of the main door <NUM>, and it is preferable that the foaming agent is injected after the main door <NUM> is arranged vertically in a temporary assembly state. Since the foaming principle is the same as that of the sub door <NUM>, its detailed description will be omitted.

Also, although the size of the main door <NUM> is the same as that of the sub door <NUM> in the aforementioned example, it may be applied to even a case where the sub door <NUM> is smaller than the main door <NUM>.

Hereinafter, the foaming injection hole, a movement direction of the foaming agent, and an air discharge relation for active movement of the foaming agent will be described in detail with reference to <FIG> and <FIG>, which show the only embodiment of the present invention disclosing a refrigerator according to claim <NUM>. The position of the foaming injection hole in this embodiment may be a little different from the position of the foaming injection hole of the aforementioned example.

Referring to the drawings, the foaming agent is injected to the first injection hole B5 and the second injection hole B4. At this time, the pressure of the foaming agent injected to the first injection hole B5 may be different from the pressure of the foaming agent injected to the second injection hole B4. That is, the foaming agent injected to the first injection hole B5 through which the foaming agent moves to a relatively wide space may be injected at relatively high pressure.

The moving path of the foaming agent will be described with reference to <FIG>. The foaming agent injected to the first injection hole B5 is injected to the foaming space formed by the side frame <NUM> and the panel assembly <NUM>. Then, the foaming agent moves to the foaming space formed by the lower frame <NUM> and the panel assembly <NUM>.

The foaming agent injected to the second injection hole B4 is first injected to the foaming space formed by the lower frame <NUM> and the panel assembly <NUM> and then moves to the foaming space formed by the side frame <NUM> and the panel assembly <NUM>.

The foaming agents simultaneously injected to the first injection hole B5 and the second injection hole B4 come across each other at the foaming space formed by the upper frame <NUM> and the panel assembly <NUM> or the foaming space formed by the side frame <NUM> and the panel assembly <NUM>.

Afterwards, after the foaming agent is fully filled in the foaming spaces formed by the upper frame <NUM> and the side frame <NUM> and the side frame <NUM>, the foaming agent may finally be filled in the space formed by the lower frame <NUM> and the panel assembly <NUM>. Of course, if the foaming agent is fully filled, the foaming injection holes B4 and B5 may be blocked by a separate element such as an injection cover.

In this case, the filling direction of the first injection hole B5 may be the same as a length direction of the side frame <NUM>. It is preferable that the filling direction of the first injection hole B5 is the same as the length direction of the side frame <NUM>. That is, the moving direction of the foaming agent injected through the first injection hole B5 is maintained in the same manner as the length direction of the side frame <NUM> without being changed. Of course, the moving direction of the foaming agent may be changed later.

It is preferable that the filling direction of the second injection hole B4 is the same as that of the side frame <NUM>. However, although the first injection hole B5 is located at the direct upper portion or direct lower portion of the side frame <NUM>, it is preferable that the second injection hole B is located at the position inclined to one side from the direct upper portion or direct lower portion of the side frame <NUM>.

That is, the foaming agent injected through the second injection hole B4 does not first move to the side frame <NUM> and flows along the lower frame <NUM> located to be orthogonal to the side frame <NUM> and finally moves along a length direction of the side frame <NUM>.

In this case, a difference between the first injection hole and the second injection hole may be caused by a sectional difference of the foaming spaces of the side frames <NUM> and <NUM>. That is, the injection hole is preferably provided at the direct upper portion or the direct lower portion of the length direction of the side frame <NUM> having a greater section, and the injection hole is preferably provided at one side (inclined toward the center of the door) inclined from the direct upper portion of the direct lower portion of the length direction of the side frame <NUM> having a smaller section.

Of course, as described above, an injection pressure at the first injection hole B5 becomes greater, and more portion of the foaming space is filled with the foaming agent substantially injected through the first injection hole B5. For example, the foaming agent injected to the first injection hole B5 may be <NUM>%, and the foaming agent injected to the second injection hole B4 may be <NUM>%.

Meanwhile, the rear frame <NUM> is provided with vent holes <NUM> formed to discharge the air remaining at the inner side of the sub door <NUM> during injection of the foaming agent. The vent holes <NUM> may be formed at a gasket mounting groove <NUM> formed for mounting of the gasket <NUM> along the rear frame <NUM>.

The gasket mounting groove <NUM> may be formed to be recessed along the circumference of the rear frame <NUM>, and the vent holes <NUM> may be formed on the gasket mounting groove <NUM> at certain intervals. After the foaming agent is fully filled, a sub door gasket <NUM> is mounted on the gasket mounting groove <NUM>. Therefore, the vent holes <NUM> may be covered by the sub door gasket <NUM> and is not exposed to the outside.

Meanwhile, the vent holes <NUM> may be formed at some area of the gasket mounting groove <NUM>. The vent holes <NUM> may be formed at certain intervals along areas A and B where the upper frame <NUM> and the side frame <NUM> are arranged as shown in <FIG>. Particularly, the vent holes <NUM> may be formed at certain intervals based on a corner where the upper frame <NUM> and the side frame <NUM> come across each other. Therefore, the air inside the sub door <NUM> may be discharged from an area adjacent to the point where the foaming agent injected to the first injection hole B5 and the foaming agent injected to the second injection hole B4 come across each other, and the air continues to be discharged out until the foaming agent is fully filled.

In other words, it is preferable that the vent holes <NUM> are formed at the corner portion of the side frame <NUM> and the upper frame <NUM> in a diagonal direction of the first injection hole B4 having the greater foaming pressure.

Meanwhile, the lower frame <NUM> may be provided with a hinge mounting portion <NUM>. Therefore, the second injection hole B4 is provided to be more inclined toward the center portion of the door than the hinge mounting portion <NUM>. That is, it is preferable that a foaming sectional area of the side frame <NUM> corresponding to the hinge mounting portion <NUM> is smaller than a foaming sectional area of the side frame <NUM> at the opposite position.

Also, the lower frame <NUM> may be provided with a sensor mounting portion <NUM>. A sensor for sensing approach of a human body or a sensor for sensing a touch input of a user or knock input to the panel assembly <NUM> may be mounted on the sensor mounting portion <NUM>. Therefore, it is preferable that the first injection hole B5 is provided to be more inclined toward the side of the door than the sensor mounting portion <NUM>.

That is, when foaming is performed after the door is arranged reversely, the foaming agent injected through the first injection hole B5 may initially move to the lower portion vertically (while the side frame <NUM> is filled with the foaming agent) and then move to the second injection hole B4 horizontally. The foaming agent injected through the second injection hole B4 may initially move to the first injection hole B5 and then move to the lower portion vertically (while the side frame <NUM> is filled with the foaming agent).

The injection cover which blocks the foaming injection holes through which the foaming agent is completely injected may be coupled with the lower frame. Therefore, the foaming injection holes are blocked at the outside of the door. Of course, the vent holes may be blocked. As a result, thermal insulation performance of the door can be obtained and at the same time esthetic appearance can be provided.

The present invention is not limited to the aforementioned embodiments, and modifications can be made in the present invention by the person with ordinary skill in the art to which the present invention pertains, within the scope of the following claims.

Claim 1:
A refrigerator comprising:
a cabinet (<NUM>) having a storage chamber;
a main door (<NUM>) rotatably coupled to the cabinet (<NUM>) and configured to open and close the storage chamber, and including a frame assembly (<NUM>) with an opening (<NUM>);
a thermal insulator (<NUM>) foamed in a foaming space that is defined by the frame assembly (<NUM>); and
a sub door (<NUM>) rotatably coupled to the main door (<NUM>) and configured to open and close the opening (<NUM>),
wherein the frame assembly (<NUM>) includes:
a first injection hole (B4) configured for the injection of foaming agent into the foaming space and positioned on a first surface of the frame assembly (<NUM>);
a second injection hole (B5) configured for the injection of foaming agent into the foaming space and spaced apart from the first injection hole (B4) on the first surface of the frame assembly;
a gasket (<NUM>) installed on a second surface of the frame assembly (<NUM>),
vent holes (<NUM>) formed on the second surface of the frame assembly and spaced apart from the first and second injection holes (B4, B5),
wherein the first surface is provided at an upper portion (<NUM>) or a lower portion (<NUM>) of the frame assembly (<NUM>), and the second surface is provided at a rear portion (<NUM>) of the frame assembly (<NUM>).