Heat exchanger

Abstract

A heat exchanger which employs porous tubes wherein tube melting at the time of attaching the porous tubes to the header tanks is prevented, the heat exchanger provided with an entry header tank which has an inflow port, an exit header tank which has an outflow port, and a plurality of tubes having passages for refrigerant flowing between the entry header tank and the exit header tank, the tubes being porous tubes which are formed by bending or rolling from flat sheets and being brazed at the two end parts to the entry header tank and exit header tank, wherein the outer surfaces of the tubes are provided with brazing materials which are used for brazing to the entry header tank and exit header tank and wherein the inner surface and outer surface of the entry header tank and exit header tank are made brazing material-free.

What is claimed is: 
     
         1 .- 15 . (canceled) 
     
     
         16 . A heat exchanger which has a plurality of tubes which is provided with refrigerant passages inside them and a pair of header tanks to which end parts of the tubes are brazed, wherein
 brazing materials which are used for brazing to the header tanks are arranged at the outer circumferential surfaces of the tubes, and   the base materials of the metal sheet members which form the header tanks are exposed at the inner circumferential surfaces and outer circumferential surfaces of the header tanks.   
     
     
         17 . The heat exchanger according to  claim 16  wherein said header tanks have header plates to which said tubes are brazed and tank plates which are assembled to said header plates and wherein the base materials of the metal sheet members which form said header plates are exposed. 
     
     
         18 . The heat exchanger according to  claim 16  wherein said header tanks have an entry side header tank into which refrigerant flows and an exit side header tank from which refrigerant flows and wherein at least one of said entry side header tank or said exit side header tank is provided inside it with separators at the two surfaces of which the base materials of the metal sheet members which form said separators are exposed. 
     
     
         19 . A heat exchanger which is provided with an entry side header tank which has an inflow port into which refrigerant flows, an exit side header tank which has an outflow port from which refrigerant is discharged, and a plurality of tubes which are provided with refrigerant passages at their insides which circulate refrigerant between said entry side header tank and exit side header tank,
 said tubes are brazed at their two end parts to said entry side header tank and said exit side header tank and at least one of said entry side header tank or said exit side header tank is provided inside it with separators which partition the inside, wherein   said separators are provided with structures for holding the brazing material.   
     
     
         20 . The heat exchanger according to  claim 19  wherein said structures for holding the brazing material are ribs which are formed at the two surfaces of said separators. 
     
     
         21 . The heat exchanger according to  claim 19  wherein said structures for holding the brazing material are a plurality of grooves or depressions which are formed at the two surfaces of said separators. 
     
     
         22 . The heat exchanger according to  claim 16  wherein said tubes are provided inside them with inner fins which have wavy shapes,
 in each said tube, a belt-shaped sheet member is folded back to form a curved end part and give different lengths to the two end parts, the folded back sheet member is formed with parallel parts, said two end parts are bent near them to form slanted parts, then are bent so that said two end parts become parallel, and a long end part of said two end parts is folded back to the short end part side and swaged, then is joined to the swaged part, whereby a flat shape is formed, and 
 each said inner fin is brazed to the inside wall surface of said tube at the bent parts of the wavy parts and is formed at one end with a flat plate part which is sandwiched between the end parts of a said belt-shaped sheet member at said swaged part to be joined with said tube. 
 
     
     
         23 . The heat exchanger according to  claim 16  wherein said plurality of tubes are provided at their outsides with outer fins for dissipating heat. 
     
     
         24 . The heat exchanger according to  claim 16  wherein the brazing material which is arranged at the outer circumferential surfaces of said tubes has an amount of Si of 3.5 wt % to 10 wt %. 
     
     
         25 . The heat exchanger according to  claim 16  wherein the brazing material which is arranged at the outer circumferential surfaces of said tubes has an amount of Si of 3.5 wt % to 7.5 wt %. 
     
     
         26 . A heat exchanger which has a plurality of tubes which are provided inside of them with refrigerant passages and a pair of header tanks to which end parts of said tubes are brazed, wherein
 said tubes are provided at their outer circumferential surfaces with a brazing material which is used for brazing to said header tanks, and,   at the portions of the inner circumferential surfaces and outer circumferential surfaces of said header tanks to which said tubes are connected, the metal which forms said header tanks does not contain brazing material, and at least one of the inner circumferential surfaces and outer circumferential surfaces of said header tanks are formed with anticorrosion layers of sacrificial materials with lower potentials than the metal which forms said header tanks.   
     
     
         27 . The heat exchanger according to  claim 16  wherein said header tanks are provided with pipes which are comprised of header plates to which said tubes are brazed and tank plates which are attached to said header plates joined together and wherein the base materials of the metal sheet members which form said pipes are exposed. 
     
     
         28 . The heat exchanger according to  claim 16  wherein said header tanks are provided with pipes which are comprised of header plates to which said tubes are brazed and tank plates which are attached to said header plates joined together and wherein at least one of the inner circumferential surfaces and outer circumferential surfaces of metal sheet members which forms pipes are provided with anticorrosion layers of sacrificial materials with low potentials. 
     
     
         29 . The heat exchanger according to  claim 16  wherein said header tanks have an entry side header tank into which refrigerant flows and an exit side header tank from which refrigerant flows and wherein at least one of said entry side header tank or said exit side header tank is provided inside it with separators at least at one surface of which a brazing material is provided. 
     
     
         30 . The heat exchanger according to  claim 27  wherein said pipes have cross-sectional shapes of any of circular shapes, oval shapes, and irregular shapes. 
     
     
         31 . The heat exchanger according to  claim 17  wherein said header tanks have an entry side header tank into which refrigerant flows and an exit side header tank from which refrigerant flows and wherein at least one of said entry side header tank or said exit side header tank is provided inside it with separators at the two surfaces of which the base materials of the metal sheet members which form said separators are exposed. 
     
     
         32 . The heat exchanger according to  claim 19  wherein said tubes are provided inside them with inner fins which have wavy shapes,
 in each said tube, a belt-shaped sheet member is folded back to form a curved end part and give different lengths to the two end parts, the folded back sheet member is formed with parallel parts, said two end parts are bent near them to form slanted parts, then are bent so that said two end parts become parallel, and a long end part of said two end parts is folded back to the short end part side and swaged, then is joined to the swaged part, whereby a flat shape is formed, and 
 each said inner fin is brazed to the inside wall surface of said tube at the bent parts of the wavy parts and is formed at one end with a flat plate part which is sandwiched between the end parts of a said belt-shaped sheet member at said swaged part to be joined with said tube. 
 
     
     
         33 . The heat exchanger according to  claim 19  wherein said plurality of tubes are provided at their outsides with outer fins for dissipating heat. 
     
     
         34 . The heat exchanger according to  claim 19  wherein the brazing material which is arranged at the outer circumferential surfaces of said tubes has an amount of Si of 3.5 wt % to 10 wt %. 
     
     
         35 . The heat exchanger according to  claim 19  wherein the brazing material which is arranged at the outer circumferential surfaces of said tubes has an amount of Si of 3.5 wt % to 7.5 wt %.