Plate heat exchanger with reinforced covers and method for the production of said reinforced covers and their assembly

Abstract

A plate heat exchanger includes a pack of superimposed heat exchanger plates, and has two cover plates mounted on the side portions of the first heat exchanger plate. The surface area of each of the two cover plates is smaller than half of the surface area of said first heat exchanger plate.

The invention claimed is: 
     
         1 . A plate heat exchanger ( 1 ) comprising:
 a pack ( 10 ) of superimposed heat exchanger plates ( 101 ) provided with alternating ridges ( 102 ) and depressions ( 103 ), said alternating ridges and depressions defining, together with the ridges ( 102 ) and depressions ( 103 ) present on another facing heat exchanger plate ( 101 ), circuits for the heat exchange fluids, and through-holes ( 104 ) configured to convey two of the heat exchange fluids in spaces between the heat exchanger plates following at least two hydraulically isolated circuits,   wherein each heat exchanger plate ( 101 ) is rectangular in shape,   wherein the heat exchanger comprises two cover plates ( 21 ,  22 ) mounted on a first one ( 107 ) of said heat exchanger plates ( 101 ),   wherein a surface area of each of said two cover plates ( 21 ,  22 ) is smaller than half the surface area of said first heat exchanger plate ( 107 ) and   wherein each of said two cover plates ( 21 ,  22 ) further comprises:   a pair of second holes ( 23 ,  231 ) shaped and positioned to correspond to said through-holes ( 104 ) in the heat exchanger plates; and   a metal ring ( 3 ,  3 ′), positioned to surround one of said second holes ( 231 ) and on a lower area of said first heat exchanger plate ( 107 ) where one of the through-holes ( 104 ) for one of the heat exchange fluids is made,   wherein said metal ring ( 3 ,  3 ′) is adapted to guarantee a hermetic seal between one of said cover plates ( 21   22 ) and said first heat exchanger plate ( 107 ).   
     
     
         2 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein an edge ( 232 ) of the one of said hole ( 231 ) in one of said cover plates ( 21 ,  22 ) is bent towards one side of the one of said cover plates ( 21 ,  22 ), forming said metal ring ( 3 ′) in a single solid piece with the one of said cover plates ( 21 ,  22 ). 
     
     
         3 . The plate heat exchanger ( 1 ) according to  claim 2 , wherein the edge of said metal ring ( 3 ′) is further bent outwardly to form a flange ( 3  G). 
     
     
         4 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein a shape and size of said two cover plates ( 21 ,  22 ) correspond to side portions of said first heat exchanger plate ( 107 ), the side portions comprising said through-holes ( 104 ) and being located in proximity to the transverse edges ( 16 ). 
     
     
         5 . The plate heat exchanger ( 1 ) according to  claim 4 , wherein each of said two cover plates ( 21 ,  22 ) has a symmetrical shape, so that each of said two cover plates can be mounted either on a right side or a left side of the pack ( 10 ). 
     
     
         6 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein each of said two cover plates ( 21 ,  22 ) comprises one or more shaped tabs, which project from an edge ( 24 ) facing a center of said first one ( 107 ) of said heat exchanger plates ( 101 ) and is configured to be inserted in one of said depressions ( 103 ) provided on said first one ( 107 ) of said heat exchanger plates ( 101 ). 
     
     
         7 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein said two cover plates ( 21 ,  22 ) provide a seat or base ( 27 ) for an application of fixing stud bolts and is provided with holes, seats or coupling means for installation of means for fixing said two cover plates ( 21 ,  22 ) one of the at least two hydraulically isolated circuits. 
     
     
         8 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein said first one ( 107 ) of said heat exchanger plates is equal to at least one of the other heat exchanger plates ( 101 ) forming the pack ( 10 ). 
     
     
         9 . The plate heat exchanger ( 1 ) according to  claim 1 , wherein said heat exchanger plates ( 101 ) are all identical or of two different types in order to define hydraulic circuits with different flow resistance. 
     
     
         10 . A method of making the plate heat exchanger ( 1 ) according to  claim 1 , comprising the following steps:
 preparing and assembling said pack ( 10 ) of superimposed heat exchanger plates;   preparing a steel sheet;   performing a stamping step of said steel sheet, wherein one or more of said cover plates ( 21 ,  22 ) are stamped at a time;   drilling said steel sheet forming said pair of second holes in pre-determined positions;   applying or forming said metal rings ( 3 ) on said steel sheet;   shearing said steel sheet in at least one shearing step to cut said cover plates ( 21 ,  22 ); and   assembling said plate heat exchanger ( 1 ), wherein said cover plates ( 21 ,  22 ) are applied to two side portions of the first heat exchanger plate ( 107 ) of said pack ( 10 ) of heat exchanger plates.   
     
     
         11 . The method according to  claim 10 , further comprising a step of bending said steel sheet to form tabs of said cover plates ( 21 ,  22 ). 
     
     
         12 . The method according to  claim 10 , further comprising a step of coupling said steel sheet with a copper sheet suitable for subsequent braze welding. 
     
     
         13 . The method according to  claim 10 , wherein two or more of said steps are grouped and carried out in a same station.