Heat exchanger

Abstract

A heat exchanger includes a plurality of tubes in which a thermal fluid flows, and a tank located at one longitudinal end portion of each tube and is brazed to the longitudinal end portions of the tubes to communicate with the tubes. The tank and the tube are respectively made of clad material plates in each of which a brazing material is clad on at least one surface of a core material. The brazing material of the tank and the brazing material of the tube respectively include Si content. Furthermore, a rate of the Si content in the brazing material of the tank is lower than that in the brazing material of the tube, and is in a range larger than 0% and equal to or smaller than 6%. Thus, meltage of the tube due to molten brazing material can be reduced during brazing of the tube and the tank.

1 . A heat exchanger comprising:
 a plurality of tubes in which a thermal fluid flows; and   a tank located at one longitudinal end portion of each tube, and is brazed to the longitudinal end portions of the tubes to communicate with the tubes, wherein   the tank and the tube are respectively made of clad material plates in each of which a brazing material is clad on at least one surface of a core material,   the brazing material of the tank and the brazing material of the tube respectively include Si content, and   a rate of the Si content in the brazing material of the tank is lower than a rate of the Si content in the brazing material of the tube, and is in a range larger than 0% and equal to or smaller than 6%.   
     
     
         2 . The heat exchanger according to  claim 1 , wherein the rate of the Si content in the brazing material of the tank is in a range larger than 0% and equal to or smaller than 5.5%. 
     
     
         3 . The heat exchanger according to  claim 2 , wherein the rate of the Si content in the brazing material of the tank is in a range between 3% and 4%. 
     
     
         4 . The heat exchanger according to  claim 1 , wherein the rate of the Si content in the brazing material of the tube is in a range between 7.5% and 12%. 
     
     
         5 . The heat exchanger according to  claim 1 , wherein
 the tube has an outer surface provided with a step portion, and   the step portion extends to a connection portion between the tube and the tank.   
     
     
         6 . The heat exchanger according to  claim 5 , wherein the step portion extends in the entire length of the tube in a tube longitudinal direction. 
     
     
         7 . The heat exchanger according to  claim 1 , wherein the longitudinal end portions of the tubes are bonded to the tank by using the brazing materials of the tank and the tube. 
     
     
         8 . The heat exchanger according to  claim 1 , wherein the tank is located at two end sides of each tube in a tube longitudinal direction to communicate with the tubes at the two end sides of each tube in the tube longitudinal direction. 
     
     
         9 . The heat exchanger according to  claim 1 , wherein the core material in the clad material plate is made of an aluminum alley. 
     
     
         10 . A heat exchanger comprising:
 a plurality of tubes in which a thermal fluid flows; and   a tank located at one longitudinal end portion of each tube, and is brazed to the longitudinal end portions of the tubes to communicate with the tubes, wherein the tank includes a core plate having a plurality of tube insertion portions into which the longitudinal end portions of the tubes are inserted to be bonded to the core plate, and a tank body connected to the core plate to define a space in the tank,   the core plate of the tank and the tube are respectively made of clad material plates in each of which a brazing material is clad on at least one surface of a core material,   the brazing material of the core plate and the brazing material of the tube respectively include Si content, and   a rate of the Si content in the brazing material of the core plate of the tank is lower than a rate of the Si content in the brazing material of the tube, and is in a range larger than 0% and equal to or smaller than 6%.   
     
     
         11 . The heat exchanger according to  claim 10 , wherein the rate of the Si content in the brazing material of the core plate of the tank is in a range larger than 0% and equal to or smaller than 5.5%. 
     
     
         12 . The heat exchanger according to  claim 11 , wherein the rate of the Si content in the brazing material of the core plate of the tank is in a range between 3% and 4%.