Patent Publication Number: US-8117792-B2

Title: Fixing structure of insulation panel of prefabricated refrigerator and prefabricated refrigerator having the same

Description:
RELATED APPLICATION 
     The present disclosure relates to subject mater contained in priority Korean Application No. 10-2006-0000676, filed on Jan. 3, 2006, which is herein expressly incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a prefabricated refrigerator, and more particularly, to a prefabricated refrigerator having high insulation efficiency by improving a fixing structure of insulation panels constituting a cabinet of the prefabricated refrigerator. 
     2. Description of the Background Art 
     Generally, a prefabricated refrigerator  1  is assembled in such a manner that sandwich panels  10 ,  20  and  30  having polyurethane foam therein are fixed to one another as shown in  FIGS. 1 and 2 . In other words, the prefabricated refrigerator  1  includes a bottom panel  10  constituting the base of a cooling space, a sidewall panel  20  constituting the surrounding of the bottom panel  10  to match a groove  10   a  of the bottom panel  10 , a cover panel  30  covering a top portion of the sidewall panel  20 , and a cooling mechanism  40  fixed to a top surface of the cover panel  30  to cool the cooling space of the prefabricated refrigerator  1 . In this case, each of the panels  10 ,  20  and  30  is provided with a groove  10   a  and a protrusion  20   a  to facilitate assembly with adjacent panels  10 ,  20  and  30 . 
     A structure of the sidewall panel  20  will be described with reference to  FIG. 3 . The sidewall panel  20  includes casings  21   a  and  22   a  formed of a metal material to prevent the sidewall panel from being damaged by external impact, and insulation portions  21   b  and  22   b  foamed inside the casings  21   a  and  22   a  by polyurethane foam. The sidewall panel  20  is assembled in such a manner that a protrusion  22   c  of each of the panels  21  and  22  is fitted to a groove  21   c.    
     However, if each of the panels  21  and  22  is completely assembled, a contact boundary surface is formed so that surfaces of the casings  21   a  and  22   a  formed of a metal material having high heat conductivity coefficient are in contact with each other. Since this boundary surface serves as a path  90  that transfers heat from the outside of the cabinet of the refrigerator to the inside corresponding to the cooling space, a problem occurs in that insulation efficiency is greatly deteriorated even though the panels  21  and  22  is provided with the insulation portions  21   b  and  22   b.    
     Accordingly, problems occur in that power consumption of the prefabricated refrigerator increases due to increase of heat conductivity through the contact surface of the casings, and the condition habitable for mold or bacilli is provided due to the dew formed in a gap by the externally transferred heat. Meanwhile, to remove mold or bacilli, a sterilizing material may be filled with the gap between the casings. In this case, another problem occurs in that quality of appearance is deteriorated. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a prefabricated refrigerator having high insulation efficiency, in which a fixing structure of insulation panels of a cabinet of the prefabricated refrigerator is improved to effectively shield heat transferred from the outside of the cabinet to the inside of the cabinet along a contact surface of the insulation panels. 
     Another object of the present invention is to provide a prefabricated refrigerator in which fixing strength of insulation panels is improved. 
     Another object of the present invention is to provide a prefabricated refrigerator having high insulation efficiency, in which a fixing structure of insulation panels is improved to minimize the amount of heat transferred in a thickness direction of the insulation panels. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a fixing structure of insulation panels of a prefabricated refrigerator, constituting a cabinet of the prefabricated refrigerator, which comprises a recess recessed on one surface of a first insulation panel having an insulation portion inside a casing; and a protrusion formed to be inserted into the recess, on one surface of a second insulation panel having an insulation portion inside a casing, wherein the insulation portions are exposed to a bottom of the recess and a front end of the protrusion. 
     The related art insulation panels surrounded by a metal casing have a problem in that external heat is transferred to the inside of a cabinet of the refrigerator through a contact surface of the metal casing in a state that the insulation panels are connected with each other. Unlike the related art insulation panels, in the present invention, the insulation portion of nonmetal material is exposed to the bottom of the recess and the front end of the protrusion so as not to form a casing of high heat conductivity on a part of a contact surface between the insulation panels, whereby a heat transfer path along the contact surface of the casing is shielded to improve insulation efficiency. 
     Since the insulation panels fixed to each other are assembled as their sides are inserted to each other, the recess and the protrusion are longitudinally formed over the whole side length of the first insulation panel and the second insulation panel. Thus, a path of external heat into the cabinet through the contact surface of the casing of metal is completely shielded. 
     The casing having relatively high strength is extended to cover both surrounding surfaces of the recess and both surrounding surfaces of the protrusion, wherein the casing is designed to endure external impact well in a state that the protrusion of the second insulation panel is inserted into the recess of the first insulation panel. 
     At this time, insulation packing materials are additionally formed on any one of the bottom of the recess and the front end of the protrusion to ensure high insulation efficiency, so that the first insulation panel is fixed to the second insulation panel in a state that the front end of the protrusion is inserted into the bottom of the recess, whereby the heat transfer path through the contact surface of the casing can be shielded and airtightness can be maintained so as not to allow external air to be permeated into the casing. 
     Meanwhile, the insulation packing materials are more preferably formed on both the bottom of the recess and the front end of the protrusion, so that air or gas, which increases heat conductivity, can be prevented from being permeated into the insulation portion. At this time, the insulation packing materials formed on the front end of the protrusion and the bottom of the recess have thicknesses of which sum is 1/15 to ⅔ of a depth of the recess. If the sum of the thicknesses of the insulation packing materials is less than 1/15 of the depth of the recess, insulation characteristic improved by the insulation packing materials is low. If the sum of the thicknesses of the insulation packing materials is more than ⅔ of the depth of the recess, the insulation panels should be excessively pulled to fix them to each other, whereby assembly is deteriorated and the depth of the protrusion inserted into the recess becomes small to adversely affect fixing strength. 
     At this time, the insulation packing materials are formed of aerosol or hard urethane, and considering elastic factors of the insulation packing materials, a compression rate of the insulation packing materials is preferably less than 10% in case of aerosol and less than 20% in case of hard urethane in a state that the first insulation panel is fixed to the second insulation panel. 
     In order to endure load as the protrusion is fixed to the recess, the depth of the recess and the height of the protrusion are preferably more than 10 mm, and the width of the recess is 0.5 times more than the depth of the recess. 
     In order to enhance fixing strength between the first insulation panel and the second insulation panel, a fixing surface between the first insulation panel and the second insulation panel may be coated with an adhesive. 
     As described above, if the insulation packing materials are inserted, the insulation panels should be pulled to compress the insulation packing materials by a predetermined value. Accordingly, the fixing structure further includes a fixing nut fixed into the casing of any one of the first insulation panel and the second insulation panel, and a fixing bolt disposed in the casing of another one of the fixing insulation panel and the second insulation panel, wherein the fixing bolt is screwed onto the fixing nut to fix the first insulation panel to the second insulation panel. Thus, the fixing strength between the insulation panels can be enhanced, and a compression rate can conveniently be applied to the insulation packing materials. 
     The casing is formed of iron material in a portion where the casing is exposed to the outside in a state that the cabinet of the refrigerator is assembled, and is formed of plastic resin material in a portion where the casing is exposed to a cooling space in a state that the cabinet of the refrigerator is assembled. Although the casing may wholly be formed of iron material, it is difficult to assemble and handle the iron casing due to heavy weight. Accordingly, the inner side of the casing is preferably formed of plastic resin material to allow a user to feel good aesthetic sense. 
     The contact surface between the first insulation panel and the second insulation panel is sealed around its periphery to prevent external air from being permeated into the contact surface. 
     Meanwhile, a prefabricated refrigerator includes a cabinet fixed by the aforementioned insulation structure, and a cooling module cooling the inside of the cabinet. 
     The insulation portion of the insulation panels includes a core member formed in a vacuum state, a vacuum insulation panel having a sealing cover surrounding the core member and attached into the casing, and polyurethane foam foamed in a space inside the casing, which is not occupied by the vacuum insulation panel. Thus, it is possible to obtain insulation characteristics that are 30% better than the related art insulation characteristics. 
     In this case, the core member is formed of an inorganic material at a vacuum range below 0.1 torr. The sealing cover includes an outmost layer formed of any one of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), a protective layer formed of any one of PET and nylon, a gas permeation preventing layer formed of any one of an aluminum thin plate, EVOH, PVDC, and aluminum deposition film, and a heating-fusion bonding layer. 
     The vacuum insulation panel further includes a getter absorbing gas externally flowed or generated from the core member, so that insulation efficiency can be maintained for a long time. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a perspective view illustrating a related art prefabricated refrigerator and a fixing structure of insulation panels thereof; 
         FIG. 2  is a perspective view illustrating the state that assembly of the prefabricated refrigerator of  FIG. 1  is completed; 
         FIG. 3  is a sectional view taken along line III-III of  FIG. 1 ; 
         FIGS. 4 and 5  illustrate a fixing structure of insulation panels for a prefabricated refrigerator according to one embodiment of the present invention, in which  FIG. 4  is a sectional view taken along line III-III of  FIG. 1  and  FIG. 5  is an enlarged view of a fixing portion of  FIG. 3 ; 
         FIG. 6  is a sectional view taken along line III-III of  FIG. 1 , illustrating a fixing structure of insulation panels for a prefabricated refrigerator according to another embodiment of the present invention; 
         FIG. 7  is a sectional view taken along line VII-VII of  FIG. 4 ; 
         FIG. 8  is a sectional view illustrating a vacuum insulation panel of  FIG. 7 ; and 
         FIG. 9  is a perspective view illustrating a cover film of a vacuum insulation panel of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     While the invention will be described in conjunction with the preferred embodiments, it will be understood that the described embodiments are not intended to limit the invention specifically to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit of the invention as defined by the appended claims. 
       FIGS. 4 and 5  illustrate a fixing structure of insulation panels for a prefabricated refrigerator according to one embodiment of the present invention, in which  FIG. 4  is a sectional view taken along line III-III of  FIG. 1  and  FIG. 5  is an enlarged view of a fixing portion of  FIG. 3 . 
     As shown, insulation panels  110  and  120  of a prefabricated refrigerator  100  according to one embodiment of the present invention include outer plates  112  and  122  of iron formed in a casing portion exposed to the outside in a state that they are assembled in a cabinet of the refrigerator, inner plates  113  and  123  of plastic formed in a casing portion exposed to a cooling space in a state that they are assembled in the cabinet of the refrigerator, a vacuum insulation panel  140  attached to the outer plates  112  and  122  between the outer plates  112  and  122  and the inner plates  113  and  123 , and insulation portions  111  and  121  filled in another portion between the outer plates  112  and  122  and the inner plates  113  and  123  and formed of polyurethane foam. 
     The first insulation panel  110  is provided with a recess  118 , and the second insulation panel  120  is provided with a protrusion  128  convexly protruded. In this case, the outer plate  112  and the inner plate  113  are extended to cover both surrounding surfaces  118   a  of the recess  118 . Likewise, the outer plate  122  and the inner plate  123  are extended to cover both surrounding surfaces  128   a  of the protrusion  128 . Thus, the first and second insulation panels  110  and  120  are engaged with each other by the extended outer and inner plates  112 ,  122 ,  113 , and  123 , so that a fixing portion of the insulation panels  110  and  120  can endure high load. 
     Insulation packing materials  114  and  124  of aerosol are respectively formed on both the bottom of the recess  118  and a front end  128   b  of the protrusion  128 . In this case, the insulation packing materials  114  and  124  are compressed at a compression rate of about 70% in a state that the first insulation panel  110  is fixed to the second insulation panel  120 , whereby airtightness is maintained so as not to flow external air into the cabinet of the refrigerator. 
     Referring to  FIG. 5 , the recess  118  is formed at a depth D of about 25 mm and a width W of 20 mm, and the insulation packing materials  114  and  124  are formed at thicknesses t 1  and t 2  of about 8 mm. 
     In order to compress the insulation packing materials  113  and  124  at a predetermined value, a fixing mechanism  130  for fixing the first insulation panel  110  to the second insulation panel  120  is additionally provided. In other words, a fixing bolt  131  is rotatably disposed movably in an axial direction in the first insulation panel  110 , and a fixing nut  122  is fixed to an inner side of the outer plate  122  of the second insulation panel  120  by blazing. Accordingly, in a state that the protrusion  128  of the second insulation panel  120  is inserted into the recess  118  of the first insulation panel  110 , the fixing bolt  131  is aligned with the fixing nut  132  so that the fixing bolt  131  is screwed onto the fixing nut  132 , whereby the first insulation panel  110  is fixed to the second insulation panel  120 . 
     As described above, since the outer plates  112  and  122  having high heat conductivity are not formed on the front end  128   b  of the protrusion  128  and the bottom  118   a  of the recess  118 , heat conductivity from the outside of the cabinet to the cabinet through the outer plates  112  and  122  can be minimized. Also, since the insulation packing materials  114  and  124  of aerosol are formed on the front end  128   b  of the protrusion  128  and the bottom  118   a  of the recess  118 , airtightness can be improved, whereby external gas or air can be prevented from flowing into the cabinet. 
     Meanwhile, as shown in  FIG. 6 , although insulation panels  210 ′ and  220 ′ are similar to those of the aforementioned refrigerator  100 , they are different from those of the aforementioned refrigerator  100  in that sides of the first and second insulation panels  210 ′ and  220 ′ are fixed to each other. 
     In this case, the second insulation panel  220 ′ is provided with two protrusions  228 ′, and the first insulation panel  210 ′ is provided with two recesses  218 ′ into which the protrusions  228 ′ are inserted. Joints  218 ′ and  228 ′ of the insulation panels  210 ′ and  220 ′ are formed in protrusion and recess shapes. A fixing portion of the insulation panels  210 ′ and  220 ′ is inclined with respect to outer plates so that a heat transfer path becomes longer within the limits of the possible, whereby cooling air can effectively be prevented from being leaked out. 
     Furthermore, the fixing portion of the insulation panels  210 ′ and  220 ′ is filled with a gasket or a sealant so as not to leak the cooling air out. 
     At this time, the bottom of the two recesses  218 ′ and the front end of the protrusion  228 ′ are provided with insulation packing materials  214  and  224  of hard urethane. 
     Since the two protrusions  228 ′ and the two recesses  218 ′ are provided to fix the insulation panels  210 ′ and  220 ′ to each other, higher airtightness than that of the aforementioned embodiment can be obtained, and heat conductivity from the outside of the cabinet to the inside of the cabinet through the outer plates  212  and  222  or the inner plates  213  and  223  can be minimized. 
       FIG. 7  is a sectional view taken along line VII-VII of  FIG. 4 ,  FIG. 8  is a sectional view illustrating the vacuum insulation panel of  FIG. 7 , and  FIG. 9  is a perspective view illustrating a cover film of the vacuum insulation panel of  FIG. 7 . In addition to the polyurethane foam  111 , the vacuum insulation panel  140  is fixed to the inner sides of the outer plates  112  and  122  inside the insulation panels  110  and  120 , so that insulation efficiency in a thickness direction of the insulation panels  110  and  120  can be improved by about 20%. 
     The vacuum insulation panel  140  includes a core member  141  formed of panels woven from inorganic glass fiber and deposited, having a vacuum state between the panels, a sealing cover  142  formed to surround the core member  141  to maintain the vacuum state of the core member  141 , and a layer-shaped getter  143  inserted into the core member  141  to maintain insulation efficiency for a sufficient time period by removing gas component flowed through the sealing cover envelope  142 . 
     The core member  141  is formed of the inorganic glass fiber known for its excellent insulation characteristics, and also is formed by depositing panels woven from thin glass fiber, whereby a high insulation effect can be obtained. A vacuum range in the vacuum insulation panel  140  is maintained below 0.1 torr. 
     The sealing cover  142  includes an outmost layer  142   a  formed of a nylon material to be exposed to the outer surface of the vacuum insulation panel  140 , a protective layer  142   b  deposited on the bottom of the outmost layer  142   a , a gas permeation preventing layer  142   c  deposited with an aluminum thin plate on the bottom of the protective layer  142   b , and a heating-fusion bonding layer  142   d  deposited on the bottom of the gas permeation preventing layer  142   c  in contact with the core member  141 . 
     The outmost layer  142   a  is formed of a nylon material having excellent elasticity at a thickness of about 25 μm. The protective layer  142   b  is also formed of a nylon material having excellent elasticity at a thickness of about 15 μm. Thus, the vacuum insulation panel  140  can be prevented from being damaged by external impact during its assembly or installation. In particular, considering that the vacuum insulation panel  140  is manufactured at a large size to improve its efficiency and thus its probability of defect increases, the vacuum insulation panel  140  of the nylon material can be prevented from being damaged by external impact or scratch, whereby the probability of defect can be avoided in advance. 
     The gas permeation preventing layer  142   c  is deposited to prevent external gas or moisture from being permeated into the core member  141 , and is preferably formed of A8000 based material containing Fe of 7 wt % to 1.3 wt %, more preferably A8079 based material. As shown in  FIG. 9 , since the A8079 material has crystal grains finer than that of the related art A1235 material, slips between the crystal grains decrease, so that allowable stress increases to endure a process step such as rolling, thereby increasing ductility. 
     Unlike the related art butene based linear low density polyethylene (LLDPE) having four carbons, since the heating-fusion bonding layer  142   d  is formed of octane based LLDPE having eight carbons at a thickness of about 50 μm, it has improved heat-resistant performance and sealing strength. Also, the heating-fusion bonding layers  142   d  of protrusions  142 ′ protruded in contact with upper and lower surfaces of the core member  141  are bonded to each other, so that vacuum of the core member  141  can be maintained more effectively. 
     As described above, the sealing cover  142  according to one embodiment of the present invention, which is formed in such a manner that the outmost layer  142   a , the protective layer  142   b , the gas permeation preventing layer  142   c  and the heating-fusion bonding layer  142   d  are deposited, has oxygen permeability of 0.005 cc/m 2  for 48 hours under the condition of relative humidity of 0% and 23° C. and water vapor transmission rate of 0.005 g/m 2  for 48 hours under the condition of relative humidity of 100% and 38° C. Therefore, it is noted that the sealing cover  142  has excellent performance in preventing external air or moisture from being permeated thereinto. 
     Also, the getter  130  is formed of an alloy of CaO or Ba—Li. 
     The aforementioned vacuum insulation panel  140  is formed at a thickness of 10 cm if the insulation panels  110  and  120  have a thickness of 30 cm, and is attached to the outer plates  112  and  122  to occupy 70% or greater of the whole area of the insulation panels  110  and  120  except the fixing portion of the insulation panels  110  and  120 . 
     As the aforementioned vacuum insulation panel  140  is applied to the insulation panels  110  and  120  for the prefabricated refrigerator, the heat conductivity coefficient in a thickness direction of the insulation panels is in the range of 0.0030 W/m·K to 0.0035 W/m·K, whereby insulation efficiency more excellent five times than that of the related art polyurethane foam can be obtained. Also, it is noted that the prefabricated refrigerator having the polyurethane foam and the vacuum insulation panel  140  as shown in  FIG. 7  has insulation efficiency 30% better than that of the related art prefabricated refrigerator. 
     Furthermore, it is noted that insulation efficiency and durability can be improved as the inclined structure having a large leakage path is formed in the joint portion of the insulation panels  110  and  210  to prevent the cooling air from being leaked out and the gasket is inserted in the joint portion of the insulation panels  110  and  210 . 
     The prefabricated refrigerator and the fixing structure of the insulation panels of the prefabricated refrigerator according to the present invention have the following advantages. 
     According to the present invention, the recess is recessed on one surface of the first insulation panel having the insulation portion inside the casing, and the protrusion is formed to be inserted into the recess, on one surface of the second insulation panel having the insulation portion inside the casing, so that the recess and the protrusion constitute a contact area of the insulation panels, and the insulation portion of nonmetal material is exposed to the bottom of the recess and the front end of the protrusion, whereby the heat transfer path along the contact area of the insulation panels is shielded to improve insulation efficiency. 
     Also, since the contact area between the first insulation panel and the second insulation panel is inclined with respect to the outer plates of the insulation panels, the path from the outside of the cabinet to the inside of the cabinet is maximized. 
     Moreover, since both the vacuum insulation panel and the polyurethane foam are provided inside the insulation panels of the prefabricated refrigerator, improved insulation characteristics in a thickness direction can be obtained. 
     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.