Heat exchanger

Abstract

Disclosed is a heat exchanger, particularly an exhaust gas heat exchanger for an internal combustion engine of a motor vehicle, comprising a housing jacket ( 6 ) that is open at both ends, and a tube bundle which is inserted into said housing jacket and is penetrated by the hot exhaust gas. The aim of the invention is to produce said heat exchanger in an inexpensive and functionally safe manner. Said aim is achieved by the fact that only the tube bundle with the tube bottoms ( 2, 3 ) thereof, which are located on the front side, are made of metal while the housing jacket ( 6 ) into which the tube bundle is inserted along with the tube bottoms ( 23 ) is made of plastic. The dimensions of the transition between at least the tube bottom that is impinged upon by the hot medium entering the tube bundle on the feeding side are selected in such a way in the direction of the housing jacket that a drop in temperature that is sufficiently great regarding the thermal resistance of the plastic is definitely obtained all the way to the contact area on the housing jacket.

1 . A heat exchanger comprising a housing jacket which is open at both ends, in which 
 a bundle composed of a plurality of individual tubes which are spaced apart from one another is inserted into the housing jacket,    the individual tubes of the bundle of tubes are held firmly and in a seal-forming fashion in end-side tube bottoms,    the tube bottoms form the end-side closures of the housing jacket,    a first of the two tube bottoms is connected to the housing jacket firmly and in a seal-forming fashion,    the second tube bottom is mounted in the jacket housing in an axially displaceable and seal-forming fashion,    the tubes are configured axially on the inside for a first hot medium to flow through them,    the tubes are located axially on the outside in a space which is formed by the housing jacket and is configured for a second medium which is cooler than the first medium to flow axially through this housing jacket,    and wherein    the individual tubes and at least the second tube bottom which lies on the hot inlet side of the heat exchanger are composed of heat-resistant metal,    the housing jacket is composed of a material which is not heat-resistant, at least at a temperature at which the first medium enters the heat exchanger,    the second tube bottom which lies on the inlet side for the first hot medium has, before it bears against the housing jacket, an intermediate region which is subjected directly to the second medium within the housing jacket and has dimensions which ensure cooling to a temperature at which the material of the housing jacket still has sufficient resistance to heat.    
   
   
       2 . The heat exchanger as claimed in  claim 1 , 
 wherein    the resistance to heat of the material of the housing jacket is at least 100° C., in particular at least 300° C., below an inlet temperature of the first medium into the heat exchanger.    
   
   
       3 . The heat exchanger as claimed in  claim 1 , 
 wherein    the housing jacket ( 6 ) is composed of plastic.    
   
   
       4 . The heat exchanger as claimed in  claim 1 , wherein 
 the fixed connection between one of the tube bottoms and the housing jacket is a beaded connection in which one of the two tube bottoms is beaded about an annular web of the housing jacket.    
   
   
       5 . The heat exchanger as claimed in  claim 1 , wherein 
 at least one flow baffle made of plastic is inserted within the space lying radially between the tube bundle and the housing jacket.    
   
   
       6 . The heat exchanger as claimed in  claim 1 , wherein 
 the plastic baffle is secured in an exclusively positively engaging fashion in the axial direction between one of the tube bottoms on the one hand, and the other tube bottom or the housing jacket on the other.    
   
   
       7 . The heat exchanger as claimed in  claim 2 , wherein the housing jacket ( 6 ) is composed of plastic.  
   
   
       8 . The heat exchanger as claimed in  claim 2 , wherein the fixed connection between one of the tube bottoms and the housing jacket is a beaded connection in which one of the two tube bottoms is beaded about an annular web of the housing jacket.  
   
   
       9 . The heat exchanger as claimed in  claim 3 , wherein the fixed connection between one of the tube bottoms and the housing jacket is a beaded connection in which one of the two tube bottoms is beaded about an annular web of the housing jacket.  
   
   
       10 . The heat exchanger as claimed in  claim 2 , wherein at least one flow baffle made of plastic is inserted within the space lying radially between the tube bundle and the housing jacket.  
   
   
       11 . The heat exchanger as claimed in  claim 3 , wherein at least one flow baffle made of plastic is inserted within the space lying radially between the tube bundle and the housing jacket.  
   
   
       12 . The heat exchanger as claimed in  claim 4 , wherein at least one flow baffle made of plastic is inserted within the space lying radially between the tube bundle and the housing jacket.  
   
   
       13 . The heat exchanger as claimed in  claim 2 , wherein the plastic baffle is secured in an exclusively positively engaging fashion in the axial direction between one of the tube bottoms on the one hand, and the other tube bottom or the housing jacket on the other.  
   
   
       14 . The heat exchanger as claimed in  claim 3 , wherein the plastic baffle is secured in an exclusively positively engaging fashion in the axial direction between one of the tube bottoms on the one hand, and the other tube bottom or the housing jacket on the other.  
   
   
       15 . The heat exchanger as claimed in  claim 4 , wherein the plastic baffle is secured in an exclusively positively engaging fashion in the axial direction between one of the tube bottoms on the one hand, and the other tube bottom or the housing jacket on the other.  
   
   
       16 . The heat exchanger as claimed in  claim 5 , wherein the plastic baffle is secured in an exclusively positively engaging fashion in the axial direction between one of the tube bottoms on the one hand, and the other tube bottom or the housing jacket on the other.