Heat exchanger having an internal bypass

Abstract

The present invention provides an exhaust recirculation cooler for transferring heat between engine exhaust and a coolant. The cooler can include a housing having a first end and a second end spaced from the first end, a heat transfer region extending through the housing and including a plurality of tubes positioned along a flow path for the coolant, and an internal bypass extending through the housing between the first end and the second end adjacent to the heat transfer region. Together, at least one of the plurality of tubes and the internal bypass provide an exhaust flow path through the cooler.

1 . An exhaust recirculation cooler for transferring heat between engine exhaust and a coolant, the heat exchanger comprising:
 a housing having a first end and a second end spaced from the first end;   a heat transfer region extending through the housing and including a plurality of tubes positioned along a flow path for the coolant; and   an internal bypass extending through the housing between the first end and the second end adjacent to the heat transfer region, together, at least one of the plurality of tubes and the internal bypass providing an exhaust flow path through the cooler.   
   
   
       2 . The exhaust recirculation cooler of  claim 1 , wherein the coolant is directed across a wall of the bypass. 
   
   
       3 . The exhaust recirculation cooler of  claim 1 , wherein the exhaust flow path is a first exhaust flow path, and further comprising a second exhaust flow path extending through an other of the plurality of tubes, and a valve located adjacent to the second end of the housing and being moveable relative to the housing to selectively direct the exhaust through the first and second exhaust flow paths. 
   
   
       4 . The exhaust recirculation cooler of  claim 1 , further comprising a header secured to an end of the plurality of tubes and defining an inlet to the heat transfer region, an outlet to the heat transfer region and one of an inlet and an outlet to the bypass. 
   
   
       5 . The exhaust recirculation cooler of  claim 1 , wherein the exhaust flow path includes two passes extending through the housing between the first and second ends in counter flow directions. 
   
   
       6 . The exhaust recirculation cooler of  claim 1 , wherein the exhaust flow path is a first exhaust flow path, and further comprising a second exhaust flow path extending through an other of the plurality of tubes, and a valve located adjacent to an outlet of the bypass and being moveable relative to the housing to selectively direct the exhaust from the first exhaust flow path through the second exhaust flow path and away from the cooler. 
   
   
       7 . An exhaust recirculation cooler comprising:
 a housing having a first end and a second end spaced from the first end and at least partially enclosing a heat transfer region;   a primary exhaust flow path including two passes extending through the housing between the first and second ends in counter flow directions, at least a portion of the primary exhaust flow path having heat-transfer augmentations and extending through the heat transfer region wherein heat is transferred from exhaust traveling through the primary exhaust flow path to a coolant flow path; and   a secondary exhaust flow path extending through the housing between the first end and the second end and being substantially free from heat transfer augmentations.   
   
   
       8 . The exhaust recirculation cooler of  claim 7 , wherein the heat transfer region includes a plurality of tubes, and further comprising an internal bypass extending through the housing between the first end and the second end adjacent to the heat transfer region. 
   
   
       9 . The exhaust recirculation cooler of  claim 8 , wherein the primary exhaust flow path extends through at least one of the plurality of tubes. 
   
   
       10 . The exhaust recirculation cooler of  claim 8 , wherein the coolant flow path is directed across a wall of the bypass. 
   
   
       11 . The heat exhaust recirculation cooler of  claim 7 , further comprising a heat exchanger core including a plurality of tubes supported in the housing and extending through the heat transfer region, the primary exhaust flow path extending through at least one of the plurality of tubes, and wherein the secondary exhaust flow path extends through an other of the plurality of tubes. 
   
   
       12 . The heat exhaust recirculation cooler of  claim 7 , further comprising a header supported at one end of the housing and at least partially defining an inlet to each of the primary and secondary exhaust flow paths. 
   
   
       13 . The exhaust recirculation cooler of  claim 7 , further comprising a valve located adjacent to the second end of the housing and being moveable relative to the housing to selectively direct the exhaust through the primary and secondary exhaust flow paths. 
   
   
       14 . The exhaust recirculation cooler of  claim 7 , further comprising a header secured to one of the first end and the second end of the housing and defining an inlet to the primary exhaust flow path, an outlet to the primary exhaust flow path, and one of an inlet and an outlet to the secondary exhaust flow path. 
   
   
       15 . A method of operating an exhaust recirculation cooler including a housing at least partially defining a heat transfer region, the method comprising the act of:
 directing engine exhaust through the housing between first and second ends of the housing around the heat transfer region and back through the heat transfer region.   
   
   
       16 . The method of  claim 15 , further comprising moving a valve relative to the housing to adjust the exhaust flow through the housing. 
   
   
       17 . The method of  claim 16 , wherein moving the valve includes moving the valve from a first position, in which the valve directs the engine exhaust from a bypass extending through the housing between the second end and the first end into the heat transfer region, and a second position, in which the valve directs the engine exhaust from the bypass away from the heat transfer region. 
   
   
       18 . The method of  claim 15 , wherein the heat exchanger includes a header supported in the housing, and wherein directing the engine exhaust through the housing includes directing the exhaust through an inlet of an exhaust flow path defined in the header and directing the engine exhaust through an outlet of the exhaust flow path defined in the header. 
   
   
       19 . The method of  claim 15 , wherein directing the engine exhaust around the heat transfer region includes directing the exhaust through an internal bypass extending through the housing. 
   
   
       20 . The method of  claim 19 , wherein the heat exchanger includes a header supported in the housing, and wherein directing the engine exhaust through the internal bypass includes directing the engine exhaust through an outlet of the internal bypass defined in the header and through an inlet of an exhaust flow path defined in the header. 
   
   
       21 . The method of  claim 15 , wherein directing the engine exhaust through the housing includes directing the engine through two passes extending through the housing between the first and second ends in counter flow directions. 
   
   
       22 . A method of operating an exhaust recirculation cooler including a housing having a first end and a second end and at least partially defining a heat transfer region, the method comprising the acts of:
 directing engine exhaust along two passes through the heat transfer region in counter flow directions;   transferring heat from the engine exhaust traveling through the heat transfer region to coolant traveling through the heat transfer region; and   directing engine exhaust from the first end of the housing toward the second end of the housing through an internal bypass in the housing and around the heat transfer region.   
   
   
       23 . The method of  claim 22 , further comprising moving a valve relative to the housing to adjust the flow of engine exhaust through the housing. 
   
   
       24 . The method of  claim 23 , wherein moving the valve includes moving the valve from a first position, in which the valve directs the engine exhaust from the bypass into the heat transfer region, and a second position, in which the valve directs the engine exhaust from the bypass away from the heat transfer region. 
   
   
       25 . The method of  claim 24 , wherein the heat exchanger includes a header supported in the housing, and wherein directing the engine exhaust through the internal bypass includes directing the engine exhaust through an outlet of the internal bypass defined in the header and through an inlet of an exhaust flow path defined in the header.