Heat recovery device and corresponding manufacturing process

Abstract

A heat recovery device comprises a body inwardly delimiting an exhaust gas circulation passage and a heat exchanger. The heat exchanger includes a casing, a plurality of exhaust gas circulation tubes and at least one grate arranged in the proximal opening of the casing. The grate comprises a wall in which orifices are arranged for receiving tubes. The grate also has an upright edge protruding toward an inside of the heat exchanger, the upright edge being rigidly attached to the casing. The wall of the grate has, around the orifices, a planar surface turned toward the body. The body has an opening delimited by a flat edge pressed against the planar surface. The planar surface and the flat edge are rigidly attached to one another to be tight with respect to exhaust gases.

1 . A heat recovery device for an exhaust line, the device comprising:
 a body inwardly delimiting an exhaust gas circulation passage; and   a heat exchanger comprising:
 a casing having a proximal edge delimiting a proximal opening; 
 a plurality of exhaust gas circulation tubes extending inside the casing; 
 at least one grate arranged in the proximal opening, the at least one grate comprising a wall in which orifices are arranged, each exhaust gas circulation tube having a proximal end engaged in one of the orifices and attached to the at least one grate, the at least one grate further having an upright edge extending around the wall and protruding from the wall toward an inside of the heat exchanger, the upright edge being rigidly attached to the casing; 
 the wall of the at least one grate having, around the orifices, a planar surface turned toward the body; 
 the body having a body opening delimited by a flat edge pressed against the planar surface; and 
 the planar surface and the flat edge being rigidly attached to one another to be tight with respect to exhaust gases. 
   
     
     
         2 . The device according to  claim 1 , wherein the planar surface and the flat edge are rigidly attached to one another by laser welding or by brazing. 
     
     
         3 . The device according to  claim 1 , wherein the upright edge of the at least one grate is rigidly attached to the proximal edge of the casing, the wall of the at least one grate being offset toward an outside of the casing. 
     
     
         4 . The device according to  claim 1 , wherein the planar surface has a closed contour and has a width of at least two millimeters. 
     
     
         5 . The device according to  claim 1 , wherein the casing includes a central tubular part having a first straight section, the proximal opening having a second section greater than the first straight section. 
     
     
         6 . The device according to  claim 5 , wherein the proximal edge of the casing is connected to the central tubular part by a tubular segment that flares from the central tubular part, the tubular segment delimiting a heat transfer fluid circulation channel along the at least one grate. 
     
     
         7 . The device according to  claim 6 , wherein the casing has a heat transfer fluid inlet and a heat transfer fluid outlet, the heat transfer fluid inlet being arranged in the central tubular part, the central tubular part having a zone protruding toward an outside of the casing extending from the heat transfer fluid inlet to the heat transfer fluid circulation channel along the at least one grate. 
     
     
         8 . The device according to  claim 6 , wherein the plurality of exhaust gas circulation tubes have protuberances forming spacers maintaining a determined spacing between the plurality of exhaust gas circulation tubes, and between the plurality of exhaust gas circulation tubes and the casing, the protuberances in contact with the casing all being located outside the heat transfer fluid circulation channel along the at least one grate. 
     
     
         9 . The device according to  claim 1 , wherein the planar surface extends in a first plane, the orifices being surrounded by a ridge adjacent to the planar surface, the ridge extending in a second plane parallel to the first plane and offset toward the inside of the heat exchanger relative to the first plane. 
     
     
         10 . The device according to  claim 1 , wherein the body opening is cut out in a wall of the body. 
     
     
         11 . A process for manufacturing a heat recovery device for an exhaust line, the process comprising the following steps:
 providing a body inwardly delimiting an exhaust gas circulation passage and a heat exchanger that includes   a casing having a proximal edge delimiting a proximal opening, a plurality of exhaust gas circulation tubes extending inside the casing, at least one grate arranged in the proximal opening, the at least one grate comprising a wall in which orifices are arranged, each exhaust gas circulation tube having a proximal end engaged in one of the orifices and attached to the at least one grate, the at least one grate further having an upright edge extending around the wall and protruding from the wall toward an inside of the heat exchanger, the upright edge being rigidly attached to the casing;
 the wall of the at least one grate having, around the orifices, a planar surface turned toward the body; 
 the body having a body opening delimited by a flat edge pressed against the planar surface; 
   assembling the casing, the plurality of exhaust gas circulation tubes and the at least one grate to one another by brazing; and   attaching the planar surface of the at least one grate and the flat edge of the body to one another by laser welding or by brazing to be tight with respect to exhaust gases.