Heat exchanger

Abstract

A heat exchanger with the ends of tubes ( 10 ) connected by being inserted into a tank ( 2 ) is disclosed. Insertion holes are formed in a protrusion ( 210 ) convex outward of the tank ( 2 ) along the tube length (X). The junction length ratio B/A is not less than 1.15, where A is the outer peripheral surface length of the tubes ( 10 ) and B the peripheral length of the junction between the tubes ( 10 ) and the tank ( 2 ). The larger the junction length ratio, the more the stress generated in the tubes ( 10 ) is distributed and reduced. Especially in the case where the junction length ratio is not less than 1.15, the stress is reduced by one half as compared with the junction length ratio of 1.0.

1 . A heat exchanger comprising: 
 a stack of a multiplicity of flat tubes; and    a pair of tanks arranged at the ends along the length (X) of the tubes and communicating with the tubes;    wherein the ends along the length (X) of the tubes are inserted into the insertion holes of the tanks;    wherein the insertion holes are formed at a protruded portion convex outward of the tanks along the tube length (X); and    wherein the junction length ratio B/A between the outer peripheral length A of the tubes and the peripheral length B of the junction between the tubes and the tanks is not less than 1.15.    
   
   
       2 . A heat exchanger according to  claim 1 , 
 wherein the junction length ratio is not more than 1.4.    
   
   
       3 . A heat exchanger according to  claim 1 , 
 wherein the tubes and the tanks are made of aluminum.    
   
   
       4 . A heat exchanger according to  claim 1 , 
 wherein the tanks are substantially rectangular as viewed from the direction along the tube stack (Y).    
   
   
       5 . A heat exchanger according to  claim 4 , 
 wherein the tanks each include a cylindrical portion extending in the direction along the tube stack (Y); and    wherein the cylindrical portion is formed by connecting a plurality of plate members including those formed with insertion holes and those not formed with insertion holes.    
   
   
       6 . A heat exchanger according to  claim 4 , 
 wherein the tank width D is not more than 1.5 times as large as the tube width C, on the assumption    that the tube width C is the outside dimension of the tubes in the direction perpendicular to both the tube length (X) and the direction of tube stack (Y), and    that the tank width D is the outside dimension of the tank in the direction perpendicular to both the tube length (X) and the direction of the tube stack (Y).