Heat exchanger having header tanks

Abstract

A heat exchanger includes a pair of header tanks and a plurality of tubes. Each of the header tanks includes an outer member and an inner member, The outer member has insertion holes allowing insertion of the tubes, while the inner member has insertion grooves allowing insertion of respective ends of the tubes. The heat exchanger is provided by brazing the so-inserted tubes to the peripheries of the insertion holes of the outer member. In order to suppress capillary phenomenon of a molten brazing filler metal in a clearance between each insertion groove and the tube, a broad portion is formed in the insertion groove to have an inside width larger than an inside width of the insertion hole. When brazing the tube to the outer member and the inner member, the molten brazing filler metal does not reach the tip surface of the tube but remains in the broad portion while maintaining the brazing strength of the tube.

1 . A heat exchanger comprising: 
 a pair of header tanks arranged at a predetermined interval, each of the header tanks including an inner member having at least one insertion groove formed therein and an outer member having at least one insertion hole formed therein and covering the inner member thereby defining a hollow part in the header tank; and    a plurality of tubes arranged between the header tanks in communication with the header tanks, each of the tubes having an end to be inserted into the insertion hole of the outer member of the header tank and also inserted into the insertion groove of the inner member of the header tank,    wherein the insertion groove has a broad portion of which inside width is larger than an inside width of the insertion hole,    wherein the tube is brazed to the outer member's part about the insertion hole.    
   
   
       2 . The heat exchanger of  claim 1 , wherein the broad portion is formed over the insertion groove.  
   
   
       3 . The heat exchanger of  claim 1 , wherein the broad portion is formed at the bottom of the insertion groove.  
   
   
       4 . The heat exchanger of  claim 1 , wherein the insertion groove is provided, at a bottom surface thereof, with a clearance forming mechanism configured to form a clearance between a tip surface of the tube and the bottom surface of the insertion groove.  
   
   
       5 . The heat exchanger of  claim 4 , wherein the clearance forming mechanism comprises the bottom surface of the insertion groove, which is inclined to the tip surface of the tube.  
   
   
       6 . The heat exchanger of  claim 5 , wherein the bottom surface inclined to the tip surface of the tube composes an arc-shaped section.  
   
   
       7 . The heat exchanger of  claim 4 , wherein the clearance forming mechanism comprises a recess formed on the bottom surface of the insertion groove, at a position opposing to the tip surface of the tube.