Evaporator comprising stacked, flat u-shaped tubes

Abstract

The invention relates to an evaporator for exchanging heat between an airflow and a coolant, comprising an array consisting of a single row of flat tubes ( 1 ) stacked in alteration with wavy dividers ( 2 ). Said dividers keep the tubes a distance (d) away from each other, their waves defining the channels for the airflow in the direction of the breadth of the tubes. Each tube has a U-shape, with the ends of each of the two limbs communicating with two chambers of a single fluid container respectively, in such a way as to define a path for the coolant in an even number of segments in the evaporator. According to the invention, the dimension (l) of the evaporator in said direction is between 20 and 48 mm and the distance (d) is between 4.0 and 7.6 mm.

1 . An evaporator for the exchange of heat between an airflow and a refrigerant fluid with the latter passing from, the liquid state to the gaseous state, especially for air-conditioning the passenger compartment of a motor vehicle, comprising a tube bank consisting of a single row of flat tubes ( 1 ) stacked alternately with corrugated spacers ( 2 ) holding the tubes spaced apart from one another by a distance d and the corrugations of which define passages or the airflow in the direction of the width of the tubes, each tube having a U-shaped configuration and the ends of its two branches communicating respectively with two chambers of a single fluid box, affixed or not affixed, in such a way as to define a journey in an odd number of passes for the refrigerant fluid in the evaporator, wherein its dimension l in the said direction lies between 20 and 48 mm and wherein the distance d lies between 4.0 and 7.6 mm.  
     
     
         2 . The evaporator as claimed in  claim 1 , wherein the total thickness (E e ) of a tube lies between 1.0 and 2.7 mm.  
     
     
         3 . The evaporator as claimed in one of claims  1  and  2 , wherein the wall thickness (e 1 ) of a tube lies between 0.2 and 0.7 mm.  
     
     
         4 . The evaporator as claimed in one of the preceding claims, wherein the internal thickness (E 1 ) of a tube lies between 0.6 and 1.8 mm.  
     
     
         5 . The evaporator as claimed in one of the preceding claims, wherein the corrugation half-period ( p/2) of the spacers lies between 1.0 and 1.8 mm.  
     
     
         6 . The evaporator as claimed in one of the preceding claims, wherein the wall thickness (e 2 ) of the spacers lies between 0.05 and 0.1 mm.  
     
     
         7 . The evaporator ( 10 ) as claimed on one of the preceding claims, wherein the tubes and the fluid box are n the form of a stack of pouches ( 11 ) each formed from two sheet-metal plates ( 12 ,  13 ) stamped into the shape of cups, the concavities of which are turned towards one another and which are brazed together so as to be leaktight at their periphery, each pouch defining one of the said tubes and featuring, at one of its ends, an increased thickness so as to define a segment of the fluid box.  
     
     
         8 . The evaporator ( 30 ) as claimed in one of  claims 1  to  6 , wherein the fluid box s an independent component ( 31 ,  32 ) featuring apertures through which penetrate the ends of the branches of the tubes ( 1 ), the said ends being brazed so as to be leaktight to the edge of the apertures.  
     
     
         9 . The evaporator as claimed in  claim 8 , wherein each tube is formed from two stamped sheet-metal places ( 1   a ,  1   b ) which are brazed together, along their lateral edges ( 1   c ) for leaktightness of the tube with respect to the outside, along a central strip for the separation of the two branches, and in intermediate regions ( 1   d ) projecting towards the inside of the tube for stiffening it.  
     
     
         10 . The evaporator as claimed in  claim 8 , wherein each tube is formed from two stamped sheet-metal plates which are brazed together, along their lateral edges for the leaktightness of the tube as regards the outside and alone a central strip for the separation of the two branches, the tube being stiffened by an insert brazed onto the inner faces of the plates.  
     
     
         11 . The evaporator as claimed in  claim 8 , wherein the tubes are extruded tubes the end of which opposite the fluid box is blocked off by a cap ( 35 ).  
     
     
         12 . The evaporator as claimed in  claim 8 , wherein the tubes are formed from pieces of sheet metal, which are folded and closed by longitudinal brazed joints and blocked off at the end opposite the fluid box, a longitudinal partition being formed by folding or by stamping for the separation of the two branches.  
     
     
         13 . The evaporator as claimed in one of  claims 8  to  12 , wherein the fluid box comprises two separate, juxtaposed parts the internal volumes of which communicate respectively with the ends of the two branches of each tube, at least one of the said parts being formed from two elements delimiting the said internal volume, one of which features the said apertures, and, if necessary, from at least one affixed internal partition separating the said internal volume into different chambers each communicating with a subset of the tubes.  
     
     
         14 . The evaporator ( 30 ) as claimed in one of  claims 8  to  12 , wherein the fluid box ( 31 ) is formed from two elements ( 33 ,  34 ) delimiting an internal volume, one of which ( 33 ) features the said apertures, and from at least one affixed internal partition separating the said internal volume into at least two chambers, the ends of the two branches of each tube communicating respectively with two of the said chambers.  
     
     
         15 . The evaporator as claimed in one of the preceding claims, in which the number of passes is chosen between 4 and 6.