Cryogenic freezer

Abstract

A rectangular double walled cryogenic freezer has a vacuum space filled with alternating layers of flexible insulating material and a reflective material. A support structure is also positioned in the vacuum space. The support structure is open-celled and provides structural support for the freezer walls to prevent wall deformation when a vacuum is drawn. The support structure may be open-cell rigid foam or a support grid sandwiched between two layers of rigid insulation material.

What is claimed is:  
     
         1 . A cryogenic freezer for storing materials at temperatures deviating greatly from ambient comprising: 
 a) an inner container, said inner container comprising four walls and a bottom;    b) an outer container enclosing the inner container and defining a vacuum space therebetween, said outer container comprising four walls and a bottom, said inner container being connected to the outer container at the top of said walls to seal said vacuum space;    c) a plurality alternating layers of reflective material and flexible insulating material; and    d) a support structure positioned in the sealed vacuum space with one side positioned adjacent to the plurality of alternating layers, said support structure substantially reducing deflection of the walls when air is evacuated from the vacuum space.    
     
     
         2 . The cryogenic freezer of  claim 1  wherein said support structure is a support grid.  
     
     
         3 . The cryogenic freezer of  claim 2  wherein the support grid includes a first set of parallel strip members oriented perpendicular to a second set of parallel strip members so that a plurality of cells are formed.  
     
     
         4 . The cryogenic freezer of  claim 3  wherein openings are provided in said parallel strip members so that the cells are open.  
     
     
         5 . The cryogenic freezer of  claim 4  where the support grid is sandwiched between layers of rigid insulation material.  
     
     
         6 . The cryogenic freezer of  claim 2  wherein the support grid is sandwiched between layers of rigid insulation material.  
     
     
         7 . The cryogenic freezer of  claim 6  wherein the rigid insulation material is fiberglass sheeting.  
     
     
         8 . The cryogenic freezer of  claim 1  where in the support structure is open-cell foam.  
     
     
         9 . The cryogenic freezer of  claim 1  wherein the vacuum space also includes a molecular sieve for absorbing gases therein.  
     
     
         10 . The cryogenic freezer of  claim 1  wherein the flexible insulation material is insulation paper.  
     
     
         11 . The cryogenic freezer of  claim 1  wherein the reflective material is reflective foil.  
     
     
         12 . The cryogenic freezer of  claim 1  further comprising a sealable vacuum port formed in the outer container.  
     
     
         13 . The cryogenic freezer of  claim 1  wherein the plurality of alternating layers are adjacent to the inner container and the support structure is adjacent to the outer container.  
     
     
         14 . A method for assembling a doubled walled vacuum insulated cryogenic freezer for storing materials at temperatures deviating greatly from ambient comprising the steps of: 
 a) providing an inner container with four walls and a bottom;    b) positioning a plurality of alternating layers of reflective material and flexible insulating material adjacent to the inner container;    c) positioning a support structure adjacent to the plurality of alternating layers for preventing deflection of the walls and bottom surface when a vacuum is drawn;    d) positioning the inner container in an outer container, the outer container having four walls and a bottom, to define a vacuum space therebetween;    e) connecting the inner container to the outer container at the top walls to seal the vacuum space; and    f) evacuating air from the vacuum space.    
     
     
         15 . The method of  claim 14  further comprising the step of sandwiching the support structure between two layers of rigid insulation material.  
     
     
         16 . The method of  claim 15  wherein the rigid insulation material is fiberglass sheets.  
     
     
         17 . The method of  claim 14  wherein the flexible insulation material is insulation paper.  
     
     
         18 . The method of  claim 14  wherein the reflective material is reflective foil.  
     
     
         19 . The method of  claim 14  wherein the support structure is a support grid.  
     
     
         20 . The method of  claim 14  wherein the support structure is open-cell foam.