Abstract:
A heat exchange device comprises two arrays of tubes through which flow two respective fluids. The device comprises a common support plate for the two arrays, which has a first portion provided with holes to act as a header plate for a first array and a second portion provided with openings for receiving in a forced fit manner the tubes of a second array with curved connectors. In one embodiment of the invention one array contains an engine cooling fluid and the other array contains a refrigerant fluid of an air-conditioning circuit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a heat exchange device, in particular for motor vehicles, and a method of manufacturing it. 
     It is more particularly concerned with a heat exchange device comprising two separate arrays of heat exchange tubes through which respective different fluids flow. 
     2. Description of the Prior Art 
     Publication DE 195 36 116 describes a device of the above kind comprising a row of flat tubes the ends of which are assembled to two tubular header boxes extending parallel to each other. Each of the header boxes is divided internally by at least one partition to define a fluid circuit comprising one subset of the tubes of the array and another fluid circuit comprising another subset of the tubes of the array. 
     The manufacture of the above prior art device necessitates complex assembly operations, in particular involving brazing. Also, it can be effected only with a single row of tubes, which limits its thermal performance. 
     One aim of the invention is to overcome the aforementioned disadvantages. 
     The invention aims in particular to provide a heat exchange device with two arrays of tubes which can be obtained by mechanical assembly operations without any brazing. 
     SUMMARY OF THE INVENTION 
     The invention proposes a heat exchange device comprising two separate arrays of heat exchange tubes adapted for the flow of different fluids respectively therethrough, and a support plate common to the two arrays and having a first portion with holes to serve as a header for a first array and a second portion with openings for receiving in a forced fit manner the tubes of a second array with curved connectors. 
     Accordingly the device of the invention combines two heat exchange arrays assembled purely mechanically by means of a support plate which serves simultaneously as the header of a first array and as means for receiving a second array in a forced fit manner. 
     The above device can be obtained entirely by mechanical assembly, without any brazing, in a single operation. 
     This results in a compact device that can include one or more rows of tubes. 
     The tubes of the first array and the tubes of the second array are advantageously parallel to each other. 
     In one embodiment of the invention the tubes of the first array and the tubes of the second array pass through respective separate first and second sets of fins. 
     As an alternative to this, the tubes of the first array and the tubes of the second array pass through a common set of fins to constitute a one-piece assembly. 
     The tubes of the first array are preferably mechanically assembled to the first part of the support plate by means of compressible seals. 
     In accordance with another feature of the invention the tubes of the first array open into a fluid box having a peripheral edge assembled to the first part of the support plate. 
     The support plate is advantageously made of a plastics material. 
     The fluid box can also be made of a plastics material and can then be friction welded to the support plate. 
     The curved connectors preferably have ends inserted into ends of the tubes of the first array. 
     In a preferred application of the invention the first array is part of an engine cooling radiator, in particular for a motor vehicle, and the second array is part of a condenser of an air conditioner. 
     In another aspect the invention comprises a method of manufacturing a heat exchanger comprising the following steps: 
     a) providing the support plate with curved connectors so that said connectors each have two ends engaged in the crimping openings of the support plate; 
     b) disposing the tubes of the first array so that their ends face the holes in the support plate; 
     c) disposing the tubes of the second array so that their ends face the ends of the curved connectors; 
     d) moving the support plate and the first and second arrays towards each other in a direction parallel to the direction of the tubes so that the ends of the tubes of the first array engage in the holes in the support plate and the ends of the tubes of the second array nest mutually with the curved connectors; and 
     e) applying a relative thrust between the support plate and the tubes of the second array so as to bring about a forced fit of the ends of the tubes of the second array and of the curved connectors. 
     The support plate is advantageously provided beforehand with a fluid box adapted to communicate subsequently with the tubes of the first array. 
     In a preferred embodiment of the invention, in operation d), the ends of the tubes of the first array are inserted into seals surrounding the holes in the support plate. 
     In another preferred embodiment of the invention, in operation a) and in operation d), the ends of the curved connectors project from one face of the support plate facing towards the first and second arrays so that the nested ends resulting from operation d) are spaced from the forced fit openings. The result of this, in operation e), is that the nested ends are a forced fit in the forced fit openings. 
     The following description is given by way of example only with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in cross-section of part of a first embodiment of a heat exchange device in accordance with the invention. 
     FIG. 2 is a top view of the device in FIG.  1 . 
     FIG. 3 is a view in section taken along the line III—III in FIG.  1 . 
     FIGS. 4,  5 ,  6  and  7  show various steps in the assembly of the device of FIG.  1 . 
     FIG. 8 is a view analogous to that of FIG. 1 showing a second embodiment of a device in accordance with the invention. 
     FIG. 9 is a view in section taken along the line IX—IX in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The device shown in FIG. 1 comprises a support plate  10  common to a first bundle or array  12  of tubes  14  and a second bundle or array  16  of tubes  18 . 
     The tubes  14  have an oval section and are disposed in two parallel rows that pass through a set of parallel fins  20  (FIGS.  1  and  3 ). 
     The tubes  18  have a circular section and are disposed in two parallel rows that pass through a set of fins  22  (FIGS.  1  and  3 ). 
     The tubes  14  and the tubes  18  are parallel to each other and the fins  20  and  22  are separated from each other by a gap  24  (FIGS. 1 and 3) to prevent any transfer of heat between the arrays  12  and  16 . 
     The tubes  14  have circular or oval ends  26  received in two rows of holes  28  through a first part  30  of the support plate  10 . This first part  30  serves as a header for the array  12 , the ends  26  of the tubes being mechanically assembled to the part  30  by means of compressible seals  32 . 
     The seals  32  are disposed inside the holes and are portions of a common part, made of rubber or a similar material, this technique being well known in the field of heat exchangers. 
     The tubes  14  of the first array open into a fluid box  34  which has a peripheral edge  36  assembled to the part  30  of the support plate on the opposite side to the array. 
     In this example the support plate  10  and the fluid box  34  are both made of a plastics material, for example a polypropylene type material, and are friction welded together. 
     The tubes  18  are connected in pairs by U-shape connectors  38 . The connectors  38  have two ends  40  inserted into the ends  42  of the tubes  18 . The ends  40  and  42  are a forced fit in two rows of openings  44  through a second part  46  of the support plate  10 . In other words this is a purely mechanical assembly entailing radial compression. 
     The openings  44  have a precise shape, with a conical entry, adapted to assure progressive radial compression of the ends  40  and  42  previously nested one within the other in order to procure a forced fit providing a strong and sealed mechanical assembly without brazing, this technique also being known in itself in the field of heat exchangers. 
     The manufacture of the device of FIG. 1 will now be described with reference to FIGS. 4 to  7 . 
     The support plate  10  is first friction welded to the fluid box  34 . The connectors  38  are then offered up facing the openings  44  in the support plate and inserted in the direction of the arrow F 1  (FIG. 4) so that their ends  40  project from the support plate  10 . 
     The arrays  12  and  16  are then disposed facing the support plate  10  so that the ends  26  of the tubes  14  face the holes  28  and the ends  42  of the tubes  18  face the ends  40  of the connectors  38 . 
     The support plate  10  and the arrays  12  and  16  are then moved towards each other in a direction parallel to the direction of the tubes. In practice it is preferable for the arrays to be fixed and for only the support plate to move in the direction of the arrows F 2 , as shown in FIG.  5 . 
     In a first phase of this movement, the ends  26  of the tubes  14  engage in the seals  32  and the ends  42  of the tubes  18  nest with the ends  40  of the curved connectors  38 . Note that after this operation the ends  40  of the curved connectors still project beyond the support plate because the crimping operation has not yet been carried out. 
     Then, in a subsequent phase shown in FIG. 6, pressure is again applied in the direction of the arrows F 3  which causes complete insertion of the ends  26  of the tubes  14  into the seals  32 , which are compressed. 
     At the same time the support plate  16  moves axially relative to the ends  40  and  42  previously nested in pairs. This procures a forced fit of the nested ends by virtue of the specific shape of the forced fit openings  44 . 
     When the above operation has been completed, a completely assembled device is obtained (FIG. 7) which is similar to that shown in FIG.  1 . 
     Of course, it is possible to carry out a similar operation at the other ends of the tubes using another support plate. The result of this is that the tubes of the array  14  are capped by two fluid boxes and that the tubes of the array  16  are connected by curved connectors at both ends. 
     In the variant shown in FIGS. 8 and 9 a single set of fins  48  is used instead of two separate sets of fins as in the previous embodiment. 
     To prevent heat transfer between the arrays  12  and  16  it is possible to provide cut-outs in each of the fins  48  in the region corresponding to the gap  24  previously referred to in connection with FIGS. 1 and 3. 
     In a preferred embodiment of the invention the array  12  is part of an engine cooling radiator, in particular for a motor vehicle. The engine cooling liquid then flows through the tubes  14 . 
     In the above specific application the array  16  is part of an air conditioner, in which case a refrigerant flows through the tubes  18 . 
     It will be understood that the device of the invention can be simply manufactured by mechanical assembly and therefore without brazing. It can be made with various dimensions, in a particularly compact arrangement, with one or more rows of tubes in one or other of the arrays. 
     Of course, the invention is not limited to the embodiments previously described and encompasses other variants. 
     In particular, the invention is not limited to the particular cases previously described of cooling an engine and condensing a refrigerant fluid.