Patent Publication Number: US-2023136969-A1

Title: Vacuum adiabatic body and refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. application Ser. No. 17/134,911, filed Dec. 28, 2020, which is a Continuation Application of U.S. application Ser. No. 15/749,161, filed Jan. 31, 2018, (now U.S. Pat. No. 10,907,887), which is a National Stage under 35 U.S.C. § 371 of PCT Application No. PCT/KR2016/008512, filed Aug. 2, 2016, which claims priority to Korean Patent Application Nos. 10-2015-0109622, 10-2015-0109626, and 10-2015-0109721, all filed Aug. 3, 2015, whose entire disclosures are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to a vacuum adiabatic body and a refrigerator. 
     2. Background 
     A vacuum adiabatic body is a product for suppressing heat transfer by vacuumizing the interior of a body thereof. The vacuum adiabatic body can reduce heat transfer by convection and conduction, and hence is applied to heating apparatuses and refrigerating apparatuses. In a typical adiabatic method applied to a refrigerator, although it is differently applied in refrigeration and freezing, a foam urethane adiabatic wall having a thickness of about 30 cm or more is generally provided. However, the internal volume of the refrigerator is therefore reduced. In order to increase the internal volume of a refrigerator, there is an attempt to apply a vacuum adiabatic body to the refrigerator. 
     First, Korean Patent No. 10-0343719 (Reference Document 1) of the present applicant has been disclosed. According to Reference Document 1, there is disclosed a method in which a vacuum adiabatic panel is prepared and then built in walls of a refrigerator, and the exterior of the vacuum adiabatic panel is finished with a separate molding such as Styrofoam (polystyrene). According to the method, additional foaming is not required, and the adiabatic performance of the refrigerator is improved. However, manufacturing cost is increased, and a manufacturing method is complicated. 
     As another example, a technique of providing walls using a vacuum adiabatic material and additionally providing adiabatic walls using a foam filling material has been disclosed in Korean Patent Publication No. 10-2015-0012712 (Reference Document 2). According to Reference Document 2, manufacturing cost is increased, and a manufacturing method is complicated. 
     As another example, there is an attempt to manufacture all walls of a refrigerator using a vacuum adiabatic body that is a single product. For example, a technique of providing an adiabatic structure of a refrigerator to be in a vacuum state has been disclosed in U.S. Patent Laid-Open Publication No. US 2004/0226956 A1 (Reference Document 3). 
     However, it is difficult to obtain an adiabatic effect of a practical level by providing the walls of the refrigerator to be in a sufficient vacuum state. Specifically, it is difficult to prevent heat transfer at a contact portion between external and internal cases having different temperatures. Further, it is difficult to maintain a stable vacuum state. Furthermore, it is difficult to prevent deformation of the cases due to a sound pressure in the vacuum state. Due to these problems, the technique of Reference Document 3 is limited to cryogenic refrigerating apparatuses, and is not applied to refrigerating apparatuses used in general households. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
         FIG.  1    is a perspective view of a refrigerator according to an embodiment. 
         FIG.  2    is a view schematically showing a main body of the refrigerator and a vacuum adiabatic body according to an embodiment. 
         FIG.  3    is a view showing various embodiments of an internal configuration of a vacuum space part. 
         FIG.  4    is a view showing various embodiments of conductive resistance sheets and peripheral parts thereof. 
         FIG.  5    is a view showing in detail a vacuum adiabatic body according to a second embodiment. 
         FIG.  6    is view showing a state in which a radiation resistance sheet is fastened to a supporting unit of  FIG.  5   . 
         FIG.  7    is a sectional view taken along line I-I′ of  FIG.  6   . 
         FIG.  8    is a sectional view taken along line II-II′ of  FIG.  6   . 
         FIG.  9    is a plan view of one vertex portion of the radiation resistance sheet of  FIG.  5   . 
         FIG.  10    illustrates graphs showing changes in adiabatic performance and changes in gas conductivity with respect to vacuum pressures by applying a simulation. 
         FIG.  11    illustrates graphs obtained by observing, over time and pressure, a process of exhausting the interior of the vacuum adiabatic body when a supporting unit is used. 
         FIG.  12    illustrates graphs obtained by comparing vacuum pressures and gas conductivities. 
         FIG.  13    is a view illustrating a correlation between a supporting unit and a first plate member of a vacuum adiabatic body according to a third embodiment, which shows any one edge portion. 
         FIG.  14    is an enlarged view of  FIG.  13   . 
         FIG.  15    is a longitudinal sectional view of  FIG.  13   . 
         FIG.  16    is a view showing the supporting unit and a radiation resistance sheet of  FIG.  13   . 
         FIG.  17    is a plan view of  FIG.  16   . 
         FIG.  18    is a view showing a vacuum adiabatic body according to a fourth embodiment. 
         FIG.  19    is a view showing a first plate member of  FIG.  18   . 
         FIG.  20    is a view showing a vacuum adiabatic body according to a fifth embodiment. 
         FIG.  21    is a view showing a vacuum adiabatic body according to a sixth embodiment. 
         FIG.  22    is a longitudinal sectional view of  FIG.  21   . 
         FIG.  23    is a view showing a vacuum adiabatic body according to a seventh embodiment. 
         FIG.  24    is a view showing a supporting unit of  FIG.  23   . 
         FIG.  25    is an exploded view of the supporting unit of  FIG.  23   . 
         FIG.  26    is a view showing a case where a plurality of radiation resistance sheets are provided in the supporting unit of  FIG.  23   . 
         FIG.  27    is a view showing the supporting unit of  FIG.  23   , viewed from the top. 
         FIG.  28    is a view showing a side of the supporting unit of  FIG.  23   . 
         FIG.  29    is a view showing an edge portion of a support plate of  FIG.  23   . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the disclosure. To avoid detail not necessary to enable those skilled in the art to practice the disclosure, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense. 
     In the following description, the term ‘vacuum pressure’ means a certain pressure state lower than atmospheric pressure. In addition, the expression that a vacuum degree of A is higher than that of B means that a vacuum pressure of A is lower than that of B. 
       FIG.  1    is a perspective view of a refrigerator according to an embodiment.  FIG.  2    is a view schematically showing a main body of the refrigerator and a vacuum adiabatic body according to an embodiment. In  FIG.  2   , a main body-side vacuum adiabatic body is illustrated in a state in which top and side walls are removed, and a door-side vacuum adiabatic body is illustrated in a state in which a portion of a front wall is removed. In addition, sections of portions at conductive resistance sheets are provided are schematically illustrated for convenience of understanding. 
     Referring to  FIGS.  1  and  2   , the refrigerator  1  includes a main body  2  provided with a cavity  9  capable of storing storage goods and a door  3  provided to open/close the main body  2 . The door  3  may be rotatably or movably disposed to open/close the cavity  9 . The cavity  9  may provide at least one of a refrigerating chamber and a freezing chamber. 
     Parts constituting a freezing cycle in which cold air is supplied into the cavity  9  may be included. Specifically, the parts include a compressor  4  for compressing a refrigerant, a condenser  5  for condensing the compressed refrigerant, an expander  6  for expanding the condensed refrigerant, and an evaporator  7  for evaporating the expanded refrigerant to take heat. As a typical structure, a fan may be installed at a position adjacent to the evaporator  7 , and a fluid blown from the fan may pass through the evaporator  7  and then be blown into the cavity  9 . A freezing load is controlled by adjusting the blowing amount and blowing direction by the fan, adjusting the amount of a circulated refrigerant, or adjusting the compression rate of the compressor, so that it is possible to control a refrigerating space or a freezing space. 
     The vacuum adiabatic body includes a first plate member (or first plate)  10  for providing a wall of a low-temperature space, a second plate member (or second plate)  20  for providing a wall of a high-temperature space, and a vacuum space part (or vacuum space)  50  defined as a gap part between the first and second plate members  10  and  20 . Also, the vacuum adiabatic body includes the conductive resistance sheets  60  and  62  for preventing heat conduction between the first and second plate members  10  and  20 . 
     A sealing part (or seal)  61  for sealing the first and second plate members  10  and  20  is provided such that the vacuum space part  50  is in a sealing state. When the vacuum adiabatic body is applied to a refrigerating or heating cabinet, the first plate member  10  may be referred to as an inner case, and the second plate member  20  may be referred to as an outer case. A machine chamber  8  in which parts providing a freezing cycle are accommodated is placed at a lower rear side of the main body-side vacuum adiabatic body, and an exhaust port  40  for forming a vacuum state by exhausting air in the vacuum space part  50  is provided at any one side of the vacuum adiabatic body. In addition, a pipeline  64  passing through the vacuum space part  50  may be further installed so as to install a defrosting water line and electric lines. 
     The first plate member  10  may define at least one portion of a wall for a first space provided thereto. The second plate member  20  may define at least one portion of a wall for a second space provided thereto. The first space and the second space may be defined as spaces having different temperatures. Here, the wall for each space may serve as not only a wall directly contacting the space but also a wall not contacting the space. For example, the vacuum adiabatic body of the embodiment may also be applied to a product further having a separate wall contacting each space. 
     Factors of heat transfer, which cause loss of the adiabatic effect of the vacuum adiabatic body, are heat conduction between the first and second plate members  10  and  20 , heat radiation between the first and second plate members  10  and  20 , and gas conduction of the vacuum space part  50 . 
     Hereinafter, a heat resistance unit provided to reduce adiabatic loss related to the factors of the heat transfer will be provided. Meanwhile, the vacuum adiabatic body and the refrigerator of the embodiment do not exclude that another adiabatic means is further provided to at least one side of the vacuum adiabatic body. Therefore, an adiabatic means using foaming or the like may be further provided to another side of the vacuum adiabatic body. 
       FIG.  3    is a view showing various embodiments of an internal configuration of the vacuum space part. First, referring to  FIG.  3   a   , the vacuum space part  50  is provided in a third space having a different pressure from the first and second spaces, preferably, a vacuum state, thereby reducing adiabatic loss. The third space may be provided at a temperature between the temperature of the first space and the temperature of the second space. Since the third space is provided as a space in the vacuum state, the first and second plate members  10  and  20  receive a force contracting in a direction in which they approach each other due to a force corresponding to a pressure difference between the first and second spaces. Therefore, the vacuum space part  50  may be deformed in a direction in which it is reduced. In this case, adiabatic loss may be caused due to an increase in amount of heat radiation, caused by the contraction of the vacuum space part  50 , and an increase in amount of heat conduction, caused by contact between the plate members  10  and  20 . 
     A supporting unit (or support)  30  may be provided to reduce the deformation of the vacuum space part  50 . The supporting unit  30  includes bars  31 . The bars  31  may extend in a direction substantially vertical to the first and second plate members  10  and  20  so as to support a distance between the first and second plate members  10  and  20 . A support plate  35  may be additionally provided to at least one end of the bar  31 . The support plate  35  connects at least two bars  31  to each other, and may extend in a direction horizontal to the first and second plate members  10  and  20 . 
     The support plate  35  may be provided in a plate shape, or may be provided in a lattice shape such that its area contacting the first or second plate member  10  or  20  is decreased, thereby reducing heat transfer. The bars  31  and the support plate  35  are fixed to each other at at least one portion, to be inserted together between the first and second plate members  10  and  20 . The support plate  35  contacts at least one of the first and second plate members  10  and  20 , thereby preventing deformation of the first and second plate members  10  and  20 . 
     In addition, based on the extending direction of the bars  31 , a total sectional area of the support plate  35  is provided to be greater than that of the bars  31 , so that heat transferred through the bars  31  can be diffused through the support plate  35 . A material of the supporting unit  30  may include a resin selected from the group consisting of PC, glass fiber PC, low outgassing PC, PPS, and LCP so as to obtain high compressive strength, low outgassing and water absorptance, low thermal conductivity, high compressive strength at high temperature, and excellent machinability. 
     A radiation resistance sheet  32  for reducing heat radiation between the first and second plate members  10  and  20  through the vacuum space part  50  will be described. The first and second plate members  10  and  20  may be made of a stainless material capable of preventing corrosion and providing a sufficient strength. The stainless material has a relatively high emissivity of 0.16, and hence a large amount of radiation heat may be transferred. 
     In addition, the supporting unit  30  made of the resin has a lower emissivity than the plate members, and is not entirely provided to inner surfaces of the first and second plate members  10  and  20 . Hence, the supporting unit  30  does not have great influence on radiation heat. Therefore, the radiation resistance sheet  32  may be provided in a plate shape over a majority of the area of the vacuum space part  50  so as to concentrate on reduction of radiation heat transferred between the first and second plate members  10  and  20 . 
     A product having a low emissivity may be preferably used as the material of the radiation resistance sheet  32 . In an embodiment, an aluminum foil having an emissivity of 0.02 may be used as the radiation resistance sheet  32 . Since the transfer of radiation heat cannot be sufficiently blocked using one radiation resistance sheet, at least two radiation resistance sheets  32  may be provided at a certain distance so as not to contact each other. In addition, at least one radiation resistance sheet may be provided in a state in which it contacts the inner surface of the first or second plate member  10  or  20 . 
     Referring to  FIG.  3   b   , the distance between the plate members is maintained by the supporting unit  30 , and a porous material  33  may be filled in the vacuum space part  50 . The porous material  33  may have a higher emissivity than the stainless material of the first and second plate members  10  and  20 . However, since the porous material  33  is filled in the vacuum space part  50 , the porous material  33  has a high efficiency for resisting the radiation heat transfer. In this embodiment, the vacuum adiabatic body can be manufactured without using the radiation resistance sheet  32 . 
     Referring to  FIG.  3   c   , the supporting unit  30  maintaining the vacuum space part  50  is not provided. Instead of the supporting unit  30 , the porous material  33  is provided in a state in which it is surrounded by a film  34 . In this case, the porous material  33  may be provided in a state in which it is compressed so as to maintain the gap of the vacuum space part  50 . The film  34  is made of, for example, a PE material, and may be provided in a state in which holes are formed therein. 
     In this embodiment, the vacuum adiabatic body can be manufactured without using the supporting unit  30 . In other words, the porous material  33  can serve together as the radiation resistance sheet  32  and the supporting unit  30 . 
       FIG.  4    is a view showing various embodiments of the conductive resistance sheets and peripheral parts thereof. Structures of the conductive resistance sheets are briefly illustrated in  FIG.  2   , but will be understood in detail with reference to  FIG.  4   . 
     First, a conductive resistance sheet proposed in  FIG.  4   a    may be preferably applied to the main body-side vacuum adiabatic body. Specifically, the first and second plate members  10  and  20  are to be sealed so as to vacuumize the interior of the vacuum adiabatic body. In this case, since the two plate members have different temperatures from each other, heat transfer may occur between the two plate members. A conductive resistance sheet  60  is provided to prevent heat conduction between two different kinds of plate members. 
     The conductive resistance sheet  60  may be provided with sealing parts  61  at which both ends of the conductive resistance sheet  60  are sealed to define at least one portion of the wall for the third space and maintain the vacuum state. The conductive resistance sheet  60  may be provided as a thin foil in units of micrometers so as to reduce the amount of heat conducted along the wall for the third space. The sealing parts  61  may be provided as welding parts. That is, the conductive resistance sheet  60  and the plate members  10  and  20  may be fused to each other. 
     In order to cause a fusing action between the conductive resistance sheet  60  and the plate members  10  and  20 , the conductive resistance sheet  60  and the plate members  10  and  20  may be made of the same material, and a stainless material may be used as the material. The sealing parts  61  are not limited to the welding parts, and may be provided through a process such as cocking. The conductive resistance sheet  60  may be provided in a curved shape. Thus, a heat conduction distance of the conductive resistance sheet  60  is provided longer than the linear distance of each plate member, so that the amount of heat conduction can be further reduced. 
     A change in temperature occurs along the conductive resistance sheet  60 . Therefore, in order to block heat transfer to the exterior of the conductive resistance sheet  60 , a shielding part (or shield)  62  may be provided at the exterior of the conductive resistance sheet  60  such that an adiabatic action occurs. In other words, in the refrigerator, the second plate member  20  has a high temperature and the first plate member  10  has a low temperature. In addition, heat conduction from high temperature to low temperature occurs in the conductive resistance sheet  60 , and hence the temperature of the conductive resistance sheet  60  is suddenly changed. Therefore, when the conductive resistance sheet  60  is opened to the exterior thereof, heat transfer through the opened place may seriously occur. 
     In order to reduce heat loss, the shielding part  62  is provided at the exterior of the conductive resistance sheet  60 . For example, when the conductive resistance sheet  60  is exposed to any one of the low-temperature space and the high-temperature space, the conductive resistance sheet  60  does not serve as a conductive resistor as well as the exposed portion thereof, which is not preferable. 
     The shielding part  62  may be provided as a porous material contacting an outer surface of the conductive resistance sheet  60 . The shielding part  62  may be provided as an adiabatic structure, e.g., a separate gasket, which is placed at the exterior of the conductive resistance sheet  60 . The shielding part  62  may be provided as a portion of the vacuum adiabatic body, which is provided at a position facing a corresponding conductive resistance sheet  60  when the main body-side vacuum adiabatic body is closed with respect to the door-side vacuum adiabatic body. In order to reduce heat loss even when the main body and the door are opened, the shielding part  62  may be preferably provided as a porous material or a separate adiabatic structure. 
     A conductive resistance sheet proposed in  FIG.  4   b    may be preferably applied to the door-side vacuum adiabatic body. In  FIG.  4   b   , portions different from those of  FIG.  4   a    are described in detail, and the same description is applied to portions identical to those of  FIG.  4   a   . A side frame  70  is further provided at an outside of the conductive resistance sheet  60 . A part for sealing between the door and the main body, an exhaust port necessary for an exhaust process, a getter port for vacuum maintenance, and the like may be placed on the side frame  70 . This is because the mounting of parts is convenient in the main body-side vacuum adiabatic body, but the mounting positions of parts are limited in the door-side vacuum adiabatic body. 
     In the door-side vacuum adiabatic body, it is difficult to place the conductive resistance sheet  60  at a front end portion of the vacuum space part, i.e., a corner side portion of the vacuum space part. This is because, unlike the main body, a corner edge portion of the door is exposed to the exterior. More specifically, if the conductive resistance sheet  60  is placed at the front end portion of the vacuum space part, the corner edge portion of the door is exposed to the exterior, and hence there is a disadvantage in that a separate adiabatic part should be configured so as to heat-insulate the conductive resistance sheet  60 . 
     A conductive resistance sheet proposed in  FIG.  4   c    may be preferably installed in the pipeline passing through the vacuum space part. In  FIG.  4   c   , portions different from those of  FIGS.  4   a  and  4   b    are described in detail, and the same description is applied to portions identical to those of  FIGS.  4   a  and  4   b   . A conductive resistance sheet having the same shape as that of  FIG.  4   a   , preferably, a wrinkled conductive resistance sheet  63  may be provided at a peripheral portion of the pipeline  64 . Accordingly, a heat transfer path can be lengthened, and deformation caused by a pressure difference can be prevented. In addition, a separate shielding part may be provided to improve the adiabatic performance of the conductive resistance sheet. 
     A heat transfer path between the first and second plate members  10  and  20  will be described with reference back to  FIG.  4   a   . Heat passing through the vacuum adiabatic body may be divided into surface conduction heat {circle around (1)} conducted along a surface of the vacuum adiabatic body, more specifically, the conductive resistance sheet  60 , supporter conduction heat {circle around (2)} conducted along the supporting unit  30  provided inside the vacuum adiabatic body, gas conduction heat (or convection) {circle around (3)} conducted through an internal gas in the vacuum space part, and radiation transfer heat {circle around (4)} transferred through the vacuum space part. 
     The transfer heat may be changed depending on various design dimensions. For example, the supporting unit may be changed such that the first and second plate members  10  and  20  can endure a vacuum pressure without being deformed, the vacuum pressure may be changed, the distance between the plate members may be changed, and the length of the conductive resistance sheet may be changed. The transfer heat may be changed depending on a difference in temperature between the spaces (the first and second spaces) respectively provided by the plate members. In the embodiment, a preferred configuration of the vacuum adiabatic body has been found by considering that its total heat transfer amount is smaller than that of a typical adiabatic structure formed by foaming polyurethane. In a typical refrigerator including the adiabatic structure formed by foaming the polyurethane, an effective heat transfer coefficient may be proposed as 19.6 mW/mK. 
     By performing a relative analysis on heat transfer amounts of the vacuum adiabatic body of the embodiment, a heat transfer amount by the gas conduction heat {circle around (3)} can become smallest. For example, the heat transfer amount by the gas conduction heat {circle around (3)} may be controlled to be equal to or smaller than 4% of the total heat transfer amount. A heat transfer amount by solid conduction heat defined as a sum of the surface conduction heat {circle around (1)} and the supporter conduction heat {circle around (2)} is largest. For example, the heat transfer amount by the solid conduction heat may reach 75% of the total heat transfer amount. A heat transfer amount by the radiation transfer heat {circle around (4)} is smaller than the heat transfer amount by the solid conduction heat but larger than the heat transfer amount of the gas conduction heat {circle around (3)}. For example, the heat transfer amount by the radiation transfer heat {circle around (4)} may occupy about 20% of the total heat transfer amount. 
     According to such a heat transfer distribution, effective heat transfer coefficients (eK: effective K) (W/mK) of the surface conduction heat {circle around (1)}, the supporter conduction heat {circle around (2)}, the gas conduction heat {circle around (3)}, and the radiation transfer heat {circle around (4)} may have an order of Math  FIG.  1   . 
         eK   solidconductionheat   &gt;eK   radiationtransferheat   &gt;eK   gasconductionheat   [Math FIG.  1 ]
 
     Here, the effective heat transfer coefficient (eK) is a value that can be measured using a shape and temperature differences of a target product. The effective heat transfer coefficient (eK) is a value that can be obtained by measuring a total heat transfer amount and a temperature of at least one portion at which heat is transferred. For example, a calorific value (W) is measured using a heating source that can be quantitatively measured in the refrigerator, a temperature distribution (K) of the door is measured using heats respectively transferred through a main body and an edge of the door of the refrigerator, and a path through which heat is transferred is calculated as a conversion value (m), thereby evaluating an effective heat transfer coefficient. 
     The effective heat transfer coefficient (eK) of the entire vacuum adiabatic body is a value given by k=QL/AΔT. Here, Q denotes a calorific value (W) and may be obtained using a calorific value of a heater. A denotes a sectional area (m2) of the vacuum adiabatic body, L denotes a thickness (m) of the vacuum adiabatic body, and ΔT denotes a temperature difference. 
     For the surface conduction heat, a conductive calorific value may be obtained through a temperature difference (ΔT) between an entrance and an exit of the conductive resistance sheet  60  or  63 , a sectional area (A) of the conductive resistance sheet, a length (L) of the conductive resistance sheet, and a thermal conductivity (k) of the conductive resistance sheet (the thermal conductivity of the conductive resistance sheet is a material property of a material and can be obtained in advance). For the supporter conduction heat, a conductive calorific value may be obtained through a temperature difference (ΔT) between an entrance and an exit of the supporting unit  30 , a sectional area (A) of the supporting unit, a length (L) of the supporting unit, and a thermal conductivity (k) of the supporting unit. 
     Here, the thermal conductivity of the supporting unit is a material property of a material and can be obtained in advance. The sum of the gas conduction heat {circle around (3)}, and the radiation transfer heat {circle around (4)} may be obtained by subtracting the surface conduction heat and the supporter conduction heat from the heat transfer amount of the entire vacuum adiabatic body. A ratio of the gas conduction heat {circle around (3)}, and the radiation transfer heat {circle around (4)} may be obtained by evaluating radiation transfer heat when no gas conduction heat exists by remarkably lowering a vacuum degree of the vacuum space part  50 . 
     When a porous material is provided inside the vacuum space part  50 , porous material conduction heat {circle around (5)} may be a sum of the supporter conduction heat {circle around (2)} and the radiation transfer heat {circle around (4)}. The porous material conduction heat {circle around (5)} may be changed depending on various variables including a kind, an amount, and the like of the porous material. 
     According to an embodiment, a temperature difference ΔT 1  between a geometric center formed by adjacent bars  31  and a point at which each of the bars  31  is located may be preferably provided to be less than 0.5° C. Also, a temperature difference ΔT 2  between the geometric center formed by the adjacent bars  31  and an edge portion of the vacuum adiabatic body may be preferably provided to be less than 0.5° C. In the second plate member  20 , a temperature difference between an average temperature of the second plate and a temperature at a point at which a heat transfer path passing through the conductive resistance sheet  60  or  63  meets the second plate may be largest. 
     For example, when the second space is a region hotter than the first space, the temperature at the point at which the heat transfer path passing through the conductive resistance sheet meets the second plate member becomes lowest. Similarly, when the second space is a region colder than the first space, the temperature at the point at which the heat transfer path passing through the conductive resistance sheet meets the second plate member becomes highest. 
     This means that the amount of heat transferred through other points except the surface conduction heat passing through the conductive resistance sheet should be controlled, and the entire heat transfer amount satisfying the vacuum adiabatic body can be achieved only when the surface conduction heat occupies the largest heat transfer amount. To this end, a temperature variation of the conductive resistance sheet may be controlled to be larger than that of the plate member. 
     Physical characteristics of the parts constituting the vacuum adiabatic body will be described. In the vacuum adiabatic body, a force by vacuum pressure is applied to all of the parts. Therefore, a material having a strength (N/m2) of a certain level may be preferably used. 
     Under such circumferences, the plate members  10  and  20  and the side frame  70  may be preferably made of a material having a sufficient strength with which they are not damaged by even vacuum pressure. For example, when the number of bars  31  is decreased so as to limit the support conduction heat, deformation of the plate member occurs due to the vacuum pressure, which may be a bad influence on the external appearance of refrigerator. The radiation resistance sheet  32  may be preferably made of a material that has a low emissivity and can be easily subjected to thin film processing. Also, the radiation resistance sheet  32  is to ensure a strength high enough not to be deformed by an external impact. The supporting unit  30  is provided with a strength high enough to support the force by the vacuum pressure and endure an external impact, and is to have machinability. The conductive resistance sheet  60  may be preferably made of a material that has a thin plate shape and can endure the vacuum pressure. 
     In an embodiment, the plate member, the side frame, and the conductive resistance sheet may be made of stainless materials having the same strength. The radiation resistance sheet may be made of aluminum having a weaker strength that the stainless materials. The supporting unit may be made of resin having a weaker strength than the aluminum. 
     Unlike the strength from the point of view of materials, analysis from the point of view of stiffness is required. The stiffness (N/m) is a property that would not be easily deformed. Although the same material is used, its stiffness may be changed depending on its shape. The conductive resistance sheets  60  or  63  may be made of a material having a predetermined strength, but the stiffness of the material is preferably low so as to increase heat resistance and minimize radiation heat as the conductive resistance sheet is uniformly spread without any roughness when the vacuum pressure is applied. The radiation resistance sheet  32  requires a stiffness of a certain level so as not to contact another part due to deformation. Particularly, an edge portion of the radiation resistance sheet may generate conduction heat due to drooping caused by the self-load of the radiation resistance sheet. Therefore, a stiffness of a certain level is required. The supporting unit  30  requires a stiffness high enough to endure a compressive stress from the plate member and an external impact. 
     In an embodiment, the plate member and the side frame may preferably have the highest stiffness so as to prevent deformation caused by the vacuum pressure. The supporting unit, particularly, the bar may preferably have the second highest stiffness. The radiation resistance sheet may preferably have a stiffness that is lower than that of the supporting unit but higher than that of the conductive resistance sheet. 
     The conductive resistance sheet may be preferably made of a material that is easily deformed by the vacuum pressure and has the lowest stiffness. Even when the porous material  33  is filled in the vacuum space part  50 , the conductive resistance sheet may preferably have the lowest stiffness, and the plate member and the side frame may preferably have the highest stiffness. 
       FIG.  5    is a view showing in detail a vacuum adiabatic body according to a second embodiment. The embodiment proposed in  FIG.  5    may be preferably applied to the door-side vacuum adiabatic body, and the description of the vacuum adiabatic body shown in  FIG.  4   b    among the vacuum adiabatic bodies shown in  FIG.  4    may be applied to portions to which specific descriptions are not provided. 
     Referring to  FIG.  5   , the vacuum adiabatic body may include a first plate member  10 , a second plate member  20 , a conductive resistance sheet  60 , and a side frame  70 , which are parts that enable a vacuum space part  50  to be separated from an external atmospheric space. The side frame  70  is formed in a bent shape, and may be provided such that an outer portion, i.e., an edge portion when viewed from the entire shape of the vacuum adiabatic body is lowered. The side frame  70  may be provided in a shape in which a gap part between the side frame  70  and the second plate member  20  is divided into a part having a high height as h 1  and a part having a low height as h 2 . 
     According to the above-described shape, the part at which the height of the side frame  70  is low can ensure a predetermined space as compared with another part at the exterior of the vacuum adiabatic body. An additional mounting part  80  in which an addition such as an exhaust port or a door hinge is mounted may be provided due to a height difference of the side frame  70 . Accordingly, it is possible to maximally ensure the internal volume of a product such as the refrigerator provided by the vacuum adiabatic body, to improve an adiabatic effect, and to sufficiently ensure functions of the product. 
     One end of the side frame  70  is fastened to the conductive resistance sheet  60  by a sealing part  61 , and the other end of the side frame  70  is fastened to the second plate member  20  by an edge part (or edge seal)  611 . The edge part  611  may be provided as a welding part. The vacuum space part  50  extends up to the edge part  611 , thereby improving an adiabatic effect. 
     The side frame  70  provides a path through which solid conduction heat passing through the conductive resistance sheet  60  passes. In the refrigerator, cold air passing through the conductive resistance sheet  60  may be transferred to the edge part  611  that is a contact point between the side frame  70  and a side part  202  of the second plate member  20 . However, the cold air may not only be reduced by the conductive resistance sheet  60  but also sufficiently resist while flowing along the side frame  70 . 
     The second plate member  20  includes a front part (or front face)  201  and the side part (or side face)  202  bent from the front part  201 , and the side part  202  is not exposed to the exterior. Thus, although dew is formed on the side part  202 , the dew is not recognized by a user, thereby improving a user&#39;s emotion. In addition, when the edge part  611  is provided as a welding part, a welding line inevitably generated due to heating is not viewed from the exterior, thereby improving a user&#39;s sense of beauty. It can be easily assumed that the side part  202  forms an outer wall of the vacuum space part  50 . 
     The edge part  611  may be provided to not only the side part  202  but also a corner portion of the front part  201  adjacent to the side part  202 , not to be easily observed by the user. As another example, the edge part  611  may be provided to an edge portion of the second plate member  20 , to enhance convenience of manufacturing while the edge part  611  is not observed with the naked eye. 
     In the refrigerator, the cold air passing through the conductive resistance sheet  60  is transferred to the side frame  70 , and hence the side frame  70  has a relatively higher temperature than the first plate member  10 . Thus, a temperature of the side frame  70  contacting a second bar  313  can be maintained higher than that of a place contacting a first bar  311 . Accordingly, although lengths of the first and second bars  311  and  313  are different from each other, heat conduction through the first bar  311  can be maintained equal to that through the second bar  313 . According to an experiment, it has been found that a second vacuum space part (or second vacuum space)  502  having a height of 1 to 2 mm can obtain a sufficient adiabatic effect equal to that of a first vacuum space part (or first vacuum space)  501  having a height of 10 to 20 mm. 
     The vacuum space part  50  includes the first vacuum space part  501  of which height is h 1  and the second vacuum space part  502  of which height is h 2  smaller than h 1 . The first and second vacuum space parts  501  and  502  can communicate with each other in a vacuum state. Accordingly, it is possible to reduce inconvenience of a manufacturing process in which a vacuum space part is separately formed. 
     A second support plate  352  may be provided to extend inside the second vacuum space part  502 . In addition, the second bar  313  having a lower height than the first bar  311  may be provided to the second support plate  352 . Thus, the gap of the second vacuum space part  502  can be maintained by the second bar  313 . The second bar  313  may be provided as a single body with the second support plate  352 . Since the heights of the first and second vacuum space parts  501  and  502  are different from each other, a first support plate  351  may not extend to the second vacuum space part  502 . Although the first support plate  351  does not extend to the second vacuum space part  502 , the flow of heat conducted from the first plate member  10  to the side frame  70  is resisted by the conductive resistance sheet  60 , and thus conduction heat through the second bar  313  can obtain an equal effect of heat resistance as compared with heat conduction through the first bar  313 . 
     As already described above, the conductive resistance sheet  60  has one purpose to resist heat transfer from the first plate member  10 . Therefore, a rapid change in temperature occurs in the conductive resistance sheet  60  along the direction of the heat transfer. It has been described that the shielding part  62  is provided to block heat transferred to the outside of the vacuum adiabatic body, corresponding to the rapid change in temperature. Similarly, heat transferred to the inside of the vacuum adiabatic body is provided by the vacuum space part  50 . The heat can obtain an adiabatic effect with respect to convection and solid conduction heat, but is weak against heat transfer caused by radiation and gas conduction. In order to solve such a problem, a radiation resistance sheet  32  may be placed even under a lower side of the conductive resistance sheet  60 . 
     Specifically, the radiation resistance sheet  32  may include first, second, and third radiation resistance sheets  321 ,  322 , and  323  sequentially provided in a direction toward the second support plate  352  from the first support plate  351 . The first radiation resistance sheet  321  may extend up to the lower side of the conductive resistance sheet  60  by passing through an end portion of the first support plate  351 . The second radiation resistance sheet  322  may extend outward by w 2  as compared with the first radiation resistance sheet  321 . The third radiation resistance sheet  323  may extend outward by w 1  as compared with the second radiation resistance sheet  322 . 
     According to such a configuration, the radiation resistance sheet  32  provided as a thin plate may be deformed by an external impact and load. This is because, if any deformed radiation resistance sheet contacts another adjacent radiation resistance sheet or the conductive resistance sheet  60 , direct heat conduction occurs, and therefore, loss of heat insulation occurs. Therefore, the first radiation resistance sheet  321  may extend not to reach the center of the conductive resistance sheet  60  even when a predetermined deformation occurs in the first radiation resistance sheet  321 . Since it is less likely that the second radiation resistance sheet  322  will contact the conductive resistance sheet  60 , the second radiation resistance sheet  322  may extend further outward by passing through the center of the conductive resistance sheet  60 . 
     However, since it is likely that the second radiation resistance sheet  322  will contact another adjacent radiation resistance sheet, a length of the second radiation resistance sheet  322  extending from the first bar  311  is preferably limited to 10 to 15 mm when the radiation resistance sheet is an aluminum sheet having a thickness of 0.3 to 0.4 mm. The third radiation resistance sheet  323  may extend outward by w 1  as compared with the second radiation resistance sheet  322 . This is because the third radiation resistance sheet  323  is supported by the second support plate  352 . 
     In  FIG.  5   , it is illustrated that the radiation resistance sheet  32  does not extend inside the second vacuum space part  502 . However, the present disclosure is not limited thereto, and the third radiation resistance sheet  323  of which at least one portion is provided to contact the second support plate  352  may extend up to the inside of the second vacuum space part  502 , thereby reducing radiation conduction heat. 
     A mounting end part (or side surface)  101  is provided at a corner of the first plate member  10 , and a rib  102  is provided in the supporting unit  30 . As the mounting end part  101  is guided by the rib  102 , the first plate member  10  and the supporting unit  30  can be placed at accurate positions, respectively. Thus, it is possible to improve fastening accuracy between parts. 
     Since the radiation resistance sheet  32  is provided as the thin plate, deformation may easily occur in the radiation resistance sheet  32  due to an external impact. Also, when the radiation resistance sheet  32  is not supported by a predetermined distance, deformation may occur in the radiation resistance sheet  32  due to an external impact and a self load. If the radiation resistance sheet  32  is deformed, another part contacts the radiation resistance sheet  32 , and hence, the adiabatic effect may be reduced. Therefore, when a radiation resistance sheet is provided, it is sufficiently considered not only that the radiation resistance sheet can sufficiently resist radiation heat but also that the above-described deformation does not occur. 
       FIG.  6    is view showing a state in which the radiation resistance sheet is fastened to the supporting unit of  FIG.  5   . Referring to  FIG.  6   , as bars  31  are inserted into holes  38  provided in the radiation resistance sheet  32 , respectively, the radiation resistance sheet  32  can be placed inside the vacuum space part  50 . The holes  38  and the bars  31  are provided at a predetermined distance. Some of the bars  31  are provided to perform a function of actually fixing the radiation resistance sheet  32  and, simultaneously, to maintain the gap of the vacuum space part  50 . 
     In other words, when the bars  31  extend to maintain the distance between the plate members, the bars  31  pass through the radiation resistance sheet  32 . At this time, the holes  38  are also to be provided to allow the bars  31  not to interfere with the radiation resistance sheet  32 . Here, bars  31  may be integrally provided to a support plate  35 . 
     The radiation resistance sheet  32  may be provided in at least two, preferably, three or more so as to perform an action of sufficient radiation resistance. In order to sufficiently derive the effect of radiation resistance using the plurality of radiation resistance sheets  321 ,  322 , and  323 , the radiation resistance sheets are preferably located such that the internal gap of the vacuum space part can be equally divided. In other words, the radiation resistance sheets are preferably located such that gaps between the radiation resistance sheets can be sufficiently maintained. To this end, gap blocks  36  (see  FIG.  7   ) may be provided to maintain gaps between the plate members  10  and  20  and the radiation resistance sheets and gaps between the radiation resistance sheets. 
     A mounting rib  384  may be provided to perform coupling between the support plates or coupling between the supporting unit and the first plate member  10 . In addition, an insertion groove  383  is provided at an edge portion of the radiation resistance sheet  32  such that the mounting rib  384  does not interfere with the radiation resistance sheet  32 . Since the mounting rib  384  is inserted through the insertion groove  383 , the radiation resistance sheet  32  can extend further outward, and can more stably resist radiation heat transfer. 
       FIG.  7    is a sectional view taken along line I-I′ of  FIG.  6   .  FIG.  8    is a sectional view taken along line II-II′ of  FIG.  6   . Here,  FIG.  7    is a sectional view showing first holes  382  through which the bar  31  passes to support the radiation resistance sheet  32  and surroundings of the first holes  382 , and  FIG.  8    is a sectional view showing second holes  381  through which the bar  31  passes without supporting the radiation resistance sheet  32  and surroundings of the second holes  382 . 
     Referring to  FIG.  7   , the plurality of radiation resistance sheets  321 ,  322 , and  323  provided in the first holes  382  and the bar  31  passing through the first holes  382  are illustrated. In addition, gap blocks  361 ,  362 , and  363  are provided to maintain gaps between the radiation resistance sheets and gaps between the radiation resistance sheets and the support plate  35 . The first hole  382  may be provided to have a diameter to an extent where only a predetermined assembly tolerance is included in the diameter of the bar  31  such that the position of the radiation resistance sheets can be guided with respect to the bar  31 . 
     When the first hole  382  is extremely small, it is difficult to put the radiation resistance sheet  32  into the bar  31 , and hence the thin radiation resistance sheet  32  is frequently damaged. Therefore, the diameter of the first hole  382  is to be provided by further reflecting a length longer than the assembly tolerance. On the other hand, when the first hole  382  is extremely large, vibration is generated even in a state in which the radiation resistance sheet  32  is supported by the bar  31 , and hence the radiation resistance sheet  32  may be deformed. 
     Therefore, the diameter of the first hole  382  is preferably provided by further reflecting a length of only the assembly tolerance. Under such circumferences, the present inventor has found that the assembly tolerance is preferably provided as 0.1 to 0.5 mm. In  FIG.  7   , it may be considered that a value obtained by adding two W 3   s  at both sides about the bar  31  is the assembly tolerance. 
     Meanwhile, the first hole  382  is preferably disposed such that any portion of the radiation resistance sheet  32  does not contact the bar  31 . This is because, if the radiation resistance sheet  32  contacts the bar  31 , heat conduction occurs, and therefore, the adiabatic effect is reduced. 
     Referring to  FIG.  8   , the plurality of radiation resistance sheets  321 ,  322 , and  323  provided in the second holes  381  and the bar  31  passing through the second holes  381  are illustrated. When the second hole  381  is extremely small, the radiation resistance sheet  32  contacts the bar  31 , and therefore, adiabatic loss may be caused. When the second hole  381  is extremely large, loss of radiation heat may occur through a gap part between the bar  31  and the second hole  381 . Under such circumferences, the present inventor has found that a sum of both gaps between the second hole  381  and the bar  31  is preferably provided as 0.3 to 1.5 mm. 
     In  FIG.  8   , a value obtained by adding two W 4   s  at both sides about the bar  31  may correspond to 0.3 to 1.5 mm. Meanwhile, the gap block  36  is provided to be larger than both of the holes  381  and  382 , so that the gap maintenance action of the radiation resistance sheet  32  can be performed without any problem. 
       FIG.  9    is a plan view of one vertex portion of the radiation resistance sheet of  FIG.  5   . Referring to  FIG.  9   , the first holes  382  having a small diameter and the second holes  381  having a larger diameter than the first holes  382  are machined in the radiation resistance sheet  32 . It has already been described that the holes  381  and  382  have a function of allowing the bar  31  to pass therethrough and a function of supporting the radiation resistance sheet. 
     The first holes  382  are preferably provided as dense as possible so as to prevent vibration of the radiation resistance sheet  32 . However, as the number of the first holes  382  is increased, a portion at which the bar  31  and the radiation resistance sheet  32  contact each other or are adjacent to each other is increased, and hence adiabatic performance may be degraded. By considering the above-described two conditions, the distance between the first holes  382  does not preferably exceed a maximum of 200 mm when the radiation resistance sheet  32  is an aluminum foil having a thickness of 0.3 mm. When the section of the door  3  is provided in a curved shape, the radiation resistance sheet  32  is also provided in a curved shape. Hence, it is required to further maintain the distance between the first holes  382  so as to avoid contact between the radiation resistance sheets. 
     Under such a background, the distance between the first holes  382 , which is indicated by W 5 , does not preferably exceed a maximum of 200 mm. In addition, the first holes  382  are preferably provided an outermost portion from the center of the radiation resistance sheet  32  and a vertex portion of the radiation resistance sheet  32 . This is for the purpose to prevent the degradation of the adiabatic performance, caused by contact between the radiation resistance sheet  32  and the bar  31 , and to prevent the degradation of the adiabatic performance by allowing the radiation resistance sheet  32  to extend as outward as possible. 
     In addition, three second holes  381  may be provided between a pair of first holes  382  adjacent to each other. In any one radiation resistance sheet, a number of the first holes  382  is more preferably smaller than that of the second holes  381  so as to prevent the degradation of the adiabatic performance. 
     Hereinafter, a vacuum pressure preferably determined depending on an internal state of the vacuum adiabatic body will be described. As already described above, a vacuum pressure is to be maintained inside the vacuum adiabatic body so as to reduce heat transfer. At this time, it will be easily expected that the vacuum pressure is preferably maintained as low as possible so as to reduce the heat transfer. 
     The vacuum space part  50  may resist the heat transfer by applying only the supporting unit  30 . Alternatively, the porous material  33  may be filled together with the supporting unit in the vacuum space part  50  to resist the heat transfer. Alternatively, the vacuum space part may resist the heat transfer not by applying the supporting unit but by applying the porous material  33 . 
     The case where only the supporting unit is applied will be described.  FIG.  10    illustrates graphs showing changes in adiabatic performance and changes in gas conductivity with respect to vacuum pressures by applying a simulation. Referring to  FIG.  10   , it can be seen that, as the vacuum pressure is decreased, i.e., as the vacuum degree is increased, a heat load in the case of only the main body (Graph 1) or in the case where the main body and the door are joined together (Graph 2) is decreased as compared with that in the case of the typical product formed by foaming polyurethane, thereby improving the adiabatic performance. However, it can be seen that the degree of improvement of the adiabatic performance is gradually lowered. Also, it can be seen that, as the vacuum pressure is decreased, the gas conductivity (Graph 3) is decreased. 
     However, it can be seen that, although the vacuum pressure is decreased, the ratio at which the adiabatic performance and the gas conductivity are improved is gradually lowered. Therefore, it is preferable that the vacuum pressure is decreased as low as possible. However, it takes long time to obtain excessive vacuum pressure, and much cost is consumed due to excessive use of a getter. In the embodiment, an optimal vacuum pressure is proposed from the above-described point of view. 
       FIG.  11    illustrates graphs obtained by observing, over time and pressure, a process of exhausting the interior of the vacuum adiabatic body when the supporting unit is used. Referring to  FIG.  11   , in order to create the vacuum space part  50  to be in the vacuum state, a gas in the vacuum space part  50  is exhausted by a vacuum pump while evaporating a latent gas remaining in the parts of the vacuum space part  50  through baking. However, if the vacuum pressure reaches a certain level or more, there exists a point at which the level of the vacuum pressure is not increased any more (Δt 1 ). 
     After that, the getter is activated by disconnecting the vacuum space part  50  from the vacuum pump and applying heat to the vacuum space part  50  (Δt 2 ). If the getter is activated, the pressure in the vacuum space part  50  is decreased for a certain period of time, but then normalized to maintain a vacuum pressure of a certain level. The vacuum pressure that maintains the certain level after the activation of the getter is approximately 1.8×10{circumflex over ( )}(−6) Torr. In the embodiment, a point at which the vacuum pressure is not substantially decreased any more even though the gas is exhausted by operating the vacuum pump is set to the lowest limit of the vacuum pressure used in the vacuum adiabatic body, thereby setting the minimum internal pressure of the vacuum space part  50  to 1.8×10{circumflex over ( )}(−6) Torr. 
       FIG.  12    illustrates graphs obtained by comparing vacuum pressures and gas conductivities. Referring to  FIG.  12   , gas conductivities with respect to vacuum pressures depending on sizes of a gap in the vacuum space part  50  are represented as graphs of effective heat transfer coefficients (eK). Effective heat transfer coefficients (eK) were measured when the gap in the vacuum space part  50  has three sizes of 2.76 mm, 6.5 mm, and 12.5 mm. 
     The gap in the vacuum space part  50  is defined as follows. When the radiation resistance sheet  32  exists inside vacuum space part  50 , the gap is a distance between the radiation resistance sheet  32  and the plate member adjacent thereto. When the radiation resistance sheet  32  does not exist inside vacuum space part  50 , the gap is a distance between the first and second plate members. 
     It can be seen that, since the size of the gap is small at a point corresponding to a typical effective heat transfer coefficient of 0.0196 W/mK, which is provided to an adiabatic material formed by foaming polyurethane, the vacuum pressure is 2.65×10{circumflex over ( )}(−1) Torr even when the size of the gap is 2.76 mm. Meanwhile, it can be seen that the point at which reduction in adiabatic effect caused by gas conduction heat is saturated even though the vacuum pressure is decreased is a point at which the vacuum pressure is approximately 4.5×10{circumflex over ( )}(−3) Torr. The vacuum pressure of 4.5×10{circumflex over ( )}(−3) Torr can be defined as the point at which the reduction in adiabatic effect caused by gas conduction heat is saturated. Also, when the effective heat transfer coefficient is 0.1 W/mK, the vacuum pressure is 1.2×10{circumflex over ( )}(−2) Torr. 
     When the vacuum space part  50  is not provided with the supporting unit but provided with the porous material, the size of the gap ranges from a few micrometers to a few hundredths of micrometers. In this case, the amount of radiation heat transfer is small due to the porous material even when the vacuum pressure is relatively high, i.e., when the vacuum degree is low. Therefore, an appropriate vacuum pump is used to adjust the vacuum pressure. The vacuum pressure appropriate to the corresponding vacuum pump is approximately 2.0×10{circumflex over ( )}(−4) Torr. 
     Also, the vacuum pressure at the point at which the reduction in adiabatic effect caused by gas conduction heat is saturated is approximately 4.7×10{circumflex over ( )}(−2) Torr. Also, the pressure where the reduction in adiabatic effect caused by gas conduction heat reaches the typical effective heat transfer coefficient of 0.0196 W/mK is 730 Torr. When the supporting unit and the porous material are provided together in the vacuum space part, a vacuum pressure may be created and used, which is middle between the vacuum pressure when only the supporting unit is used and the vacuum pressure when only the porous material is used. 
     The vacuum adiabatic body proposed in the present disclosure may be preferably applied to refrigerators. However, the application of the vacuum adiabatic body is not limited to the refrigerators, and may be applied in various apparatuses such as cryogenic refrigerating apparatuses, heating apparatuses, and ventilation apparatuses. 
     Hereinafter, a vacuum adiabatic body according to a third embodiment will be described. 
       FIG.  13    is a view illustrating a correlation between a supporting unit and a first plate member of a vacuum adiabatic body according to a third embodiment, which shows any one edge portion.  FIG.  14    is an enlarged view of  FIG.  13   .  FIG.  15    is a longitudinal sectional view of  FIG.  13   . 
     Referring to  FIGS.  13  to  15   , the vacuum adiabatic body according to the embodiment includes a first plate member (or first plate)  110  providing a wall for a low-temperature space, a second plate member (or second plate)  120  providing a wall for a high-temperature space, and a vacuum space part (or vacuum space)  150  defined as a gap part between the first and second plate members  110  and  120 , and a supporting unit (or support)  130  for reducing deformation of the vacuum space part  150 . 
     The supporting unit  130  may include a plurality of bars  131  interposed between the first and second plate members  110  and  120 , a first support plate  135  provided at one ends of the plurality of bars  131 , and a second support plate  136  provided at the other ends of the plurality of bars  131 . 
     For pitches between the plurality of bars  131 , a pitch at a portion adjacent to an edge portion of the first plate member  110  or an edge portion of the second plate member  120  may be formed narrower than those of the other portions. This is because the supporting ability of the edge portion of each of the first and second plate members  110  and  120  is weak as compared with the other portions. 
     The first support plate  135  may be disposed to contact the first plate member  110 , and the second support plate  136  may be disposed to contact the second plate member  120 . Each of the first and second support plates  135  and  136  may be provided in a grid shape. Accordingly, the area of each of the first and second support plates  135  and  136  respectively contacting the first and second plate members  110  and  120  is decreased, thereby reducing a heat transfer amount. 
     Extending parts (or extension tabs)  112  for reinforcing the supporting ability of the first plate member  110  with the supporting unit  130  may be formed at the first plate member  110 . The extending parts  112  may be formed to extend downward from an end portion of the first plate member  110 . 
     Fixing parts (or fixing brackets)  137  and  138  may be formed at the second support plate  136 . At least one portion of each of the fixing parts  137  and  138  may contact the extending part  112 . 
     The extending part  112  may be provided in plurality, and the fixing parts  137  and  138  may be formed to correspond to the respective extending parts  112 . The fixing parts  137  and  138  may include a first fixing part (or first fixing bracket)  137  contacting one surface of the extending part  112 . 
     The first fixing part  137  may be formed to extend upward from the second support plate  136 . Meanwhile, in these figures, the first fixing part  137  is disposed at the outside of the extending part  112 . Alternatively, the first fixing part  137  may be provided at the inside of the extending part  112 . 
     The fixing parts  137  and  138  may include a second fixing part (or second fixing bracket)  138  surrounding the extending part  112 . The second fixing part  138  may be formed to extend upward from the second support plate  136 . A groove into which the extending part  112  is inserted may be formed in the second support plate  136 . Accordingly, the extending part  112  can be coupled to the second fixing part  138 . 
     As shown in  FIG.  13   , the first fixing parts  137  may be arranged in a row at one side of the second support plate  136 , and the second fixing parts  138  may be arranged in a row at another side of the second support plate  136 . However, the present disclosure is not limited to the above-described arrangement. 
     The vacuum adiabatic body further includes a conductive resistance sheet  160  for preventing heat conduction between the first and second plate members  110  and  120 . The conductive resistance sheet  160  may include sealing parts (or seals)  161  at which both ends of the conductive resistance sheet  160  are sealed so as to define at least one portion of a wall for the vacuum space part  150  and to maintain the vacuum state. The conductive resistance sheet  160  may be provided as a thin foil in unit of micrometers so as to reduce the amount of heat conduction flowing along the wall for the vacuum space part  150 . 
     A side frame  170  may be provided at an outside of the conductive resistance sheet  160 . One side of the conductive resistance sheet  160  may be fastened to the first plate member  110 , and the other side of the conductive resistance sheet  160  may be fastened to the side frame  170 . 
     A plurality of bars  131  for maintaining a distance between the side frame  170  and the second plate member  120  may be interposed between the side frame  170  and the second plate member  120 . The shortest distance between a bar disposed at an outermost portion and a plurality of bars interposed between the side frame  170  and the second plate members  120  among the plurality of bars  131  interposed between the first and second plate members  110  and  120  is shorter than a pitch between the plurality of bars  131  interposed between the first and second plate members  110  and  120 . This is for the purpose to prevent deformation of the side frame  170 . 
     Welding parts as the sealing parts  161  may be formed at the conductive resistance sheet  160 . Specifically, both the sides of the conductive resistance sheet  160  may be respectively mounted on the first plate member  110  and the side frame  170  and then welded. 
       FIG.  16    is a view showing the supporting unit and the radiation resistance sheet of  FIG.  13   .  FIG.  17    is a plan view of  FIG.  16   . Referring to  FIGS.  16  and  17   , the supporting unit  130  may be mounted on the second plate member  120 . The supporting unit  130  may include a plurality of radiation resistance sheets  132 ,  133 , and  134 . 
     The plurality of radiation resistance sheets  132 ,  133 , and  134  may be penetrated by a plurality of bars  131 . The radiation resistance sheets  132 ,  133 , and  134  may be disposed to be spaced apart from each other by a separate spacing member. 
     First and second fixing parts  137  and  138  protruding upward are provided to the second support plate  136 . The plurality of radiation resistance sheets  132 ,  133 , and  134  are disposed over a range as wide as possible within the vacuum space part  150 , which is effective in terms of adiabatic performance. However, if the first and second fixing parts  137  and  138  contact the plurality of radiation resistance sheets  132 ,  133 , and  134 , the adiabatic performance may be degraded by heat transfer. 
     Therefore, the first and second fixing parts  137  and  138  are to be disposed so as not to contact the plurality of radiation resistance sheets  132 ,  133 , and  134 . Thus, a depression part (or notch)  132   a  in which the first fixing part  13  can be accommodated is formed in a first radiation resistance sheet  132 . A depression part  132   b  in which the second fixing part  138  can be accommodated is formed in the first radiation resistance sheet  132 . Accordingly, the first and second fixing parts  137  and  138  cannot contact the first radiation resistance sheet. Depression parts in which the first and second fixing parts  137  and  138  are accommodated may also be formed in second and third radiation resistance sheets  133  and  134 . 
       FIG.  18    is a view showing a vacuum adiabatic body according to a fourth embodiment.  FIG.  19    is a view showing a first plate member of  FIG.  18   . 
     Referring to  FIGS.  18  and  19   , unlike the aforementioned embodiment, the vacuum adiabatic body of this embodiment is not provided with any fixing part, and includes an extending part having a different shape. 
     The vacuum adiabatic body of this embodiment includes a first plate member (or first plate)  210  and a second plate member (or second plate)  220 . A first support plate  235  contacts the first plate member  210 , and a second support plate  236  contacts the second plate member  220 . At least one bar  231  may be interposed between the first and second support plates  235  and  236 . 
     At least one radiation resistance sheet  232  may be provided between the first and second support plates  235  and  236 . The radiation resistance sheet  232  may be penetrated by the at least one bar  231 . An extending part (or extension bracket)  212  extending downward may be provided to the first plate member  210 . The extending part  212  may be provided in plurality. 
     The extending part  212  may contact a side of the first support plate  235 . As the extending part  212  is provided in plurality, the first plate member  210  may be fixed to the first support plate  235 . In these figures, it can be seen that the first support plate  235  is inserted into the first plate member  210  through the extending part  212 . 
     A lower end portion of the extending part  212  may be located above the radiation resistance sheet  232  such that the extending part  212  does not contact the radiation resistance sheet  232 . The extending part  212  may be integrally formed with the first plate member  210 . However, the present disclosure is not limited thereto, and the extending part  212  and the first plate member  210  may be provided as separate components from each other. 
       FIG.  20    is a view showing a vacuum adiabatic body according to a fifth embodiment. Referring to  FIG.  20   , the vacuum adiabatic body of this embodiment is different from that of the aforementioned embodiment in only the shape of an extending part. 
     Specifically, the vacuum adiabatic body of this embodiment includes an extending part (or extension bracket)  312  extending downward from an edge portion of a first plate member  310 . A first support plate  335  contacts a lower end of the first plate member (or first plate)  310 , and the extending part  312  may be provided to contact the first support plate  335 . 
     The extending part  312  may be provided to extend downward from the entire edge portion of the first plate member  310 . That is, the extending part  312  may be formed longer than the extending part  212  of the aforementioned embodiment. In this case, only one extending part  312  is provided at one corner of the first plate member  310 . 
     The extending part  312  may be integrally formed with the first plate member  310 . However, the present disclosure is not limited thereto, and the extending part  312  and the first plate member  310  may be provided as separate components from each other. 
     The extending part  312  may extend downward within a length range where it does not contact a radiation resistance sheet. Accordingly, the first plate member  310  can be supported by being fixed to the first support plate  335 . 
       FIG.  21    is a view showing a vacuum adiabatic body according to a sixth embodiment.  FIG.  22    is a longitudinal sectional view of  FIG.  21   . 
     Referring to  FIGS.  21  and  22   , in the vacuum adiabatic body of this embodiment, an extending part may be formed to protrude downward from a surface of a plate member instead of an edge portion of the plate member. 
     The vacuum adiabatic body of this embodiment includes a first plate member (or first plate)  410 , a first support plate  435  contacting a lower portion of the first plate member  410 , and at least one bar  431  supporting the first support plate  435 . The at least one bar  431  may be between the first support plate  435  and a second support plate  436 . 
     An extending part (or recess)  412  protruding toward the first support plate  435  may be formed in the first plate member  410 . Unlike the extending part of the aforementioned embodiment, the extending part  412  is formed to protrude downward from any one place of the first plate member  410  instead of an edge portion of the first plate member  410 . 
     The extending part  412  may be formed in the planar first plate member  410  using a forming mold. The extending part  412  may be formed to protrude in a shape corresponding to a groove provided in the first support plate  435 . Thus, the extending part  412  can be inserted into the groove provided in the first support plate  435 . 
     Accordingly, the first support plate  435  can be supported by being fixed to the first support plate  435 . Meanwhile, in the present disclosure, it has been described that the first plate member is fixed to the supporting unit. However, instead of the first plate member, the second plate member may be fixed to the supporting unit. 
       FIG.  23    is a view showing a vacuum adiabatic body according to a seventh embodiment. Referring to  FIG.  23   , the vacuum adiabatic body according to the seventh embodiment includes a first plate member (or first plate)  1110 , a second plate member (or second plate)  1120 , and a supporting unit (or support)  1130 . The supporting unit  1130  includes a first support plate  1135 , a second support plate  1136 , at least one bar  1131 , and a radiation resistance sheet  1132 . 
     The first support plate  1135  may contact the first plate member  1110 , and the second support plate  1136  may contact the second plate member  1120 . Here, each of the first plate member  1110 , the second plate member  1120 , the first support plate  1135 , the second support plate  1136 , and the radiation resistance sheet  1132  is formed as a curved surface, and has a larger curvature as it is more distant from the center of curvature. 
       FIG.  24    is a view showing the supporting unit of  FIG.  23   .  FIG.  25    is an exploded view of the supporting unit of  FIG.  23   . Referring to  FIGS.  24  and  25   , the supporting unit  1130  includes a first support plate  1135 , a second support plate  1136 , and a plurality of bars  1131 . 
     The supporting unit  1130  may be formed into a structure in which the plurality of bars  1131  are fixed to the second support plate  1136 , and the first support plate  1135  is attachable/detachable to/from the other ends of the plurality of bars  1131 . Therefore, an assembly of the second support plate  1136  and the plurality of bars  1131  may be referred to as a “base,” and the first support plate  1135  may be referred to as a “cover.” 
     The first support plate  1135  may be provided with a plurality of insertion parts or holes  1137  into which the respective bars  1131  are inserted. A pitch between the plurality of insertion parts  1137  has a small value as compared with that between the plurality of bars  1131  attached to the second support plate  1136 . 
     A distance R 1  from the center of curvature to the first support plate  1135 , a distance R 2  from the center of curvature to the radiation resistance sheet  1132 , and a distance R 3  from the center of curvature to the second support plate  1136  are sequentially increased. Pitches P 1 , P 2 , and P 3  between the plurality of bars  1131  are sequentially increased as they are distant from the center of curvature. Here, P 1  refers to a pitch between the plurality of insertion parts  1137  provided in the first support plate  1135 , P 2  refers to a pitch between through-holes provided in the radiation resistance sheet  1132 , and P 3  refers to a pitch between spots at which the second support plate  1136  and the plurality of bars  1131  are connected to each other. 
       FIG.  26    is a view showing a case where a plurality of radiation resistance sheets is provided in the supporting unit of  FIG.  23   . Referring to  FIG.  26   , a plurality of radiation resistance sheets  1132 ,  1133 , and  1134  may be provided between the first and second support plates  1135  and  1136 . A first radiation resistance sheet  1132 , a second radiation resistance sheet  1133 , and a third radiation resistance sheet  1134  are sequentially disposed in a direction distant from the center of curvature. 
     A plurality of through-holes  1132   a ,  1133   a , and  1134   a  penetrated by the bars  1131  may be formed in the radiation resistance sheets  1132 ,  1133 , and  1134 , respectively. 
     Pitches between the plurality of through-holes  1132   a ,  1133   a , and  1134   a  may be sequentially increased as they are distant from the center of curvature. 
     End portions of the plurality of radiation resistance sheets  1132 ,  1133 , and  1134  may be lengthened as they are distant from the center of curvature. This can be considered in the same context as that the pitches between the plurality of through-holes  1132   a ,  1133   a , and  1134   a  are increased. 
       FIG.  27    is a view showing the supporting unit of  FIG.  23   , viewed from the top.  FIG.  28    is a view showing a side of the supporting unit of  FIG.  23   .  FIG.  29    is a view showing an edge portion of a support plate of  FIG.  23   . 
     Referring to  FIGS.  27  to  29   , the second support plate  1136  includes a plurality of connection ribs  1136   a  and  1136   b  forming grid shapes. In  FIG.  27   , the plurality of connection ribs  1136   a  and  1136   b  include a plurality of first connection ribs  1136   a  extending in the horizontal or first direction and a plurality of second connection ribs  1136   b  extending in the vertical or second direction. 
     The plurality of first connection ribs  1136   a  are formed to extend along the circumferential direction of the second support plate  1136  forming a curved surface, and the plurality of second connection ribs  1136   b  are formed to extend along the direction of the center of curvature of the second support plate  1136 . That is, the plurality of first connection ribs  1136   a  are curved such that each of the plurality of first connection ribs  1136   a  forms a curve, and each of the plurality of second connection ribs  1136   b  forms a straight line. 
     Each of the plurality of first connection ribs  1136   a  may be formed thinner than each of the plurality of second connection ribs  1136   b . This is for the purpose that each of the plurality of first connection ribs  1136   a  is well warped to form a curve. In this case, each of the plurality of second connection ribs  1136   b  may be formed thicker than each of the plurality of first connection ribs  1136   a , thereby reinforcing its strength. 
     For example, the thickness of each of the plurality of first connection ribs  1136   a  may be formed to be equal to or greater than 1 mm and equal to or smaller than 3 mm. Like the second support plate  1136 , a plurality of first connection ribs and a plurality of second connection ribs may also be provided in the first support plate  1135 . Bars  1131  may be respectively provided at spots at which the first and second connection ribs  1136   a  and  1136   b.    
     A plurality of connection parts (or connection bases)  1138  may be formed at portions at which the respective bars  1131  and the second support plate  1136  meet. A pitch between the plurality of connection parts  1138  may be formed larger than that between the plurality of insertion parts  1137 . This is because the plurality of connection parts  1138  is disposed more distant from the center of curvature than the plurality of insertion parts  1137 . 
     However, the plurality of connection parts  1138  are provided to the first support plate  1135 , and the plurality of insertion parts  1137  are provided in the second support plate  1136 , a pitch between the plurality of connection parts  1138  may be formed smaller than that between the plurality of insertion parts  1137 . This is because the plurality of connection parts  1138  is disposed closer to the center of curvature than the plurality of insertion parts  1137 . 
     Each of the plurality of connection parts  1138  may be formed to be rounded. Accordingly, it is possible to reduce damage caused by a front end in machining or assembling of the second support plate  1136 . A round size R may be approximately 0.05 mm to 1 mm. 
     A third connection rib  1139  formed at the edge portion of the second support plate  1136  is formed thicker than the first and second connection ribs  1136   a  and  1136   b . For example, the third connection rib  1139  may be formed thicker by about 0.2 mm than the first and second connection ribs  1136   a  and  1136   b.    
     Also, the third connection rib  1139  may be made of a material having a larger density than the first and second connection ribs  1136   a  and  1136   b . This is for the purpose to complement strength because the edge portion of the second support plate  1136  may be weak in terms of strength. Accordingly, it is possible to prevent damage of the second support plate  1136 . 
     According to the present disclosure, the vacuum adiabatic body can be industrially applied to various adiabatic apparatuses. The adiabatic effect can be enhanced, so that it is possible to improve energy use efficiency and to increase the effective volume of an apparatus. 
     Embodiments provide a vacuum adiabatic body and a refrigerator, which can obtain a sufficient adiabatic effect in a vacuum state and be applied commercially. Embodiments also provide a structure for improving the supporting ability of a plate member provided in a vacuum adiabatic body. Embodiments also provide a vacuum adiabatic body of which at least one portion forms a curved surface and a refrigerator including the same. 
     In one embodiment, a vacuum adiabatic body includes: a first plate member defining at least one portion of a wall for a first space; a second plate member defining at least one portion of a wall for a second space having a different temperature from the first space; a sealing part sealing the first plate member and the second plate member to provide a third space that has a temperature between the temperature of the first space and the temperature of the second space and is in a vacuum state; a supporting unit maintaining the third space; a heat resistance unit for decreasing a heat transfer amount between the first plate member and the second plate member; and an exhaust port through which a gas in the third space is exhausted, wherein an extending part extending toward the third space to be coupled to the supporting unit is provided to at least one of the first and second plate members, and the extending part is formed to extend downward from an edge portion of the at least one of the first and second plate members. 
     In another embodiment, a vacuum adiabatic body includes: a first plate member defining at least one portion of a wall for a first space; a second plate member defining at least one portion of a wall for a second space having a different temperature from the first space; a sealing part sealing the first plate member and the second plate member to provide a third space that has a temperature between the temperature of the first space and the temperature of the second space and is in a vacuum state; a supporting unit maintaining the third space; a heat resistance unit for decreasing a heat transfer amount between the first plate member and the second plate member; and an exhaust port through which a gas in the third space is exhausted, wherein the supporting unit includes support plates respectively contacting the first and second plate members, and each of the first and second plate members and the support plates is provided as a curved surface, and is formed such that its curvature is increased as it is distant from the center of curvature. 
     In still another embodiment, a vacuum adiabatic body includes: a first plate member defining at least one portion of a wall for a first space; a second plate member defining at least one portion of a wall for a second space having a different temperature from the first space; a sealing part sealing the first plate member and the second plate member to provide a third space that has a temperature between the temperature of the first space and the temperature of the second space and is in a vacuum state; a supporting unit maintaining the third space; a heat resistance unit including at least one radiation resistance sheet provided in a plate shape inside the third space to decrease a heat transfer amount between the first plate member and the second plate member; and an exhaust port through which a gas in the third space is exhausted, wherein the radiation resistance sheet is provided with at least one first hole having a small diameter and at least one second hole having a large diameter, so that bars of the supporting unit are inserted into the first and second holes, and a number of the first holes is smaller than that of the second holes. 
     In still another embodiment, a refrigerator includes: a main body provided with an internal space in which storage goods are stored; and a door provided to open/close the main body from an external space, wherein, in order to supply a refrigerant into the main body, the refrigerator includes: a compressor for compressing the refrigerant; a condenser for condensing the compressed refrigerant; an expander for expanding the condensed refrigerant; and an evaporator for evaporating the expanded refrigerant to take heat, wherein at least one of the main body and the door includes a vacuum adiabatic body, wherein the vacuum adiabatic body includes: a first plate member defining at least one portion of a wall for the internal space; a second plate member defining at least one portion of a wall for the external space; a sealing part sealing the first plate member and the second plate member to provide a vacuum space part that has a temperature between a temperature of the internal space and a temperature of the external space and is in a vacuum state; a supporting unit maintaining the vacuum space part; a heat resistance unit connected to at least one of the first and second plate members, the heat resistance unit decreasing a heat transfer amount between the first plate member and the second plate member; and an exhaust port through which a gas in the vacuum space part is exhausted, wherein at least one of the first and second plate members is provided with an extending part extending toward the vacuum space part, the extending part being coupled to the supporting unit. 
     According to the present disclosure, it is possible to provide a vacuum adiabatic body having a vacuum adiabatic effect and a refrigerator including the same. Also, the vacuum adiabatic body of the present disclosure can effectively overcome radiation heat transfer of the vacuum space part. According to the present disclosure, it is possible to sufficiently resist heat transfer through a structure for resisting radiation heat transfer. 
     Also, it is possible to improve the supporting ability of the plate member using the supporting unit. Also, components constituting the vacuum adiabatic body are not formed to have curved surfaces through injection molding, but formed by changing only an assembling process, so that it is possible to manufacture a vacuum adiabatic body formed in a curved shape. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.