Heat exchanger and method of manufacturing outside plate used for header tanks of heat exchanger

Abstract

A method of manufacturing an outside plate used for a heat exchanger header tank configured such that an outside plate having an outwardly bulging portion, an inside plate, and an intermediate plate are brazed together in layers. A thick portion is formed on an outside-plate forming metal plate at a center portion with respect to the width direction thereof. Subsequently, a press work is performed on the outside-plate forming metal plate so as to form the outwardly bulging portion by making use of the thick portion. A connection portion having a curvature radius of 1 mm or less is formed between an inner wall surface of the outwardly bulging portion and each of surfaces of the outside plate located on the opposite sides of the outwardly bulging portion. This method enables manufacture of an outside plate which reduces the weight while securing sufficient withstanding pressure.

1 . A heat exchanger comprising a pair of header tanks disposed apart from each other and a plurality of flat heat exchange tubes disposed in parallel between the two header tanks and having opposite end portions connected to the respective header tanks, each of the two header tanks being configured such that an outside plate, an inside plate, and an intermediate plate intervening between the outside and inside plates are brazed together in layers, the outside plate having an outwardly bulging portion extending in a longitudinal direction thereof and having an opening closed by the intermediate plate, the inside plate having a plurality of tube insertion holes in the form of through-holes formed in a region corresponding to the outwardly bulging portion of the outside plate and spaced apart from one another along a longitudinal direction of the inside plate, and the intermediate plate having a plurality of communication holes in the form of through-holes formed for allowing the respective tube insertion holes of the inside plate to communicate with the interior of the outwardly bulging portion of the outside plate, 
 wherein the outside plate of each header tank is formed of a metal plate and through a press work performed thereon, and a connection portion between an inner wall surface of the outwardly bulging portion of the outside plate and a surface of the outside plate which surface is joined to the intermediate plate has a curvature radius of 1 mm or less.    
   
   
       2 . A heat exchanger according to  claim 1 , wherein the connection portion between the inner wall surface of the outwardly bulging portion and the surface of the outside plate joined to the intermediate plate has a curvature radius of 0.5 mm or less.  
   
   
       3 . A heat exchanger according to  claim 1 , wherein the outside plate has a thickness of 2 mm or greater.  
   
   
       4 . A method of manufacturing an outside plate used for a heat exchanger header tank which is configured such that an outside plate, an inside plate, and an intermediate plate intervening between the outside and inside plates are brazed together in layers, the outside plate having an outwardly bulging portion extending in a longitudinal direction thereof and having an opening closed by the intermediate plate, the inside plate having a plurality of tube insertion holes in the form of through-holes formed in a region corresponding to the outwardly bulging portion of the outside plate and spaced apart from one another along a longitudinal direction of the inside plate, and the intermediate plate having a plurality of communication holes in the form of through-holes formed for allowing the respective tube insertion holes of the inside plate to communicate with the interior of the outwardly bulging portion of the outside plate, the method comprising the steps of: 
 forming a thick portion on an outside-plate forming metal plate at a center portion with respect to the width direction thereof, the thick portion being thicker than the remaining thin portion; and    performing a press work on the outside-plate forming metal plate so as to form the outwardly bulging portion by making use of the thick portion such that a connection portion having a curvature radius of 1 mm or less is formed between an inner wall surface of the outwardly bulging portion and each of surfaces of the outside plate located on the opposite sides of the outwardly bulging portion and being continuous with the inner wall surface.    
   
   
       5 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 4 , wherein the thick portion is formed by performing a press work on the outside-plate forming metal plate.  
   
   
       6 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 5 , wherein the thick portion of the outside-plate forming metal plate has a thickness 1.05 to 1.5 times that of the remaining thin portion.  
   
   
       7 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 4 , wherein a connection portion having a curvature radius of 0.5 mm or less is formed between the inner wall surface of the outwardly bulging portion and each of the surfaces of the outside plate located on the opposite sides of the outwardly bulging portion and being continuous with the inner wall surface.  
   
   
       8 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 4 , wherein the outside plate has a thickness of 2 mm or greater in its final shape.  
   
   
       9 . A method of manufacturing an outside plate used for a heat exchanger header tank which is configured such that an outside plate, an inside plate, and an intermediate plate intervening between the outside and inside plates are brazed together in layers, the outside plate having an outwardly bulging portion extending in a longitudinal direction thereof and having an opening closed by the intermediate plate, the inside plate having a plurality of tube insertion holes in the form of through-holes formed in a region corresponding to the outwardly bulging portion of the outside plate and spaced apart from one another along a longitudinal direction of the inside plate, and the intermediate plate having a plurality of communication holes in the form of through-holes formed for allowing the respective tube insertion holes of the inside plate to communicate with the interior of the outwardly bulging portion of the outside plate, the method comprising the steps of: 
 performing a first press work on an outside-plate forming metal plate so as to form a preliminary bulging portion having a bulging height greater than that of the outwardly bulging portion; and    performing a second press work on the outside-plate forming metal plate having the preliminary bulging portion, while restraining the outside-plate forming metal plate from the opposite sides with respect to the width direction thereof, so as to form the outwardly bulging portion from the preliminary bulging portion such that a connection portion having a curvature radius of 1 mm or less is formed between an inner wall surface of the outwardly bulging portion and each of surfaces of the outside plate located on the opposite sides of the outwardly bulging portion and being continuous with the inner wall surface.    
   
   
       10 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 9 , wherein the step of performing the second press work includes cutting opposite side edge portions of the outside-plate forming metal plate by use of one of dies used for the press work before formation of the outwardly bulging portion from the preliminary bulging portion, and restraining the outside-plate forming metal plate having the preliminary bulging portion from the opposite sides with respect to the width direction thereof by use of the die.  
   
   
       11 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 9 , wherein a connection portion having a curvature radius of 0.5 mm or less is formed between the inner wall surface of the outwardly bulging portion and each of the surfaces of the outside plate located on the opposite sides of the outwardly bulging portion and being continuous with the inner wall surface.  
   
   
       12 . A method of manufacturing an outside plate used for a heat exchanger header tank according to  claim 9 , wherein the outside plate has a thickness of 2 mm or greater in its final shape.