Abstract:
For a technical object whose temperature is to be controlled, in particular a battery for an electric vehicle drive, there is provided a heat exchanger arrangement, the heat exchanger of which is in the form of a heat-exchanging pouch which has an inflow and outflow duct and which is in heat-conducting contact with internal surfaces of the object whose temperature is to be controlled. The heat-exchanging pouch is produced in a simple manner by means of edge welding of two foil pieces arranged one above the other. The mounting of said heat-exchanging pouch in a narrow gap space of a heat exchanger arrangement, and good heat transfer to adjacent walls, are made possible by means of a pressure pouch which is likewise formed from a foil material and which is filled with a compressible medium.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European application No. 12196196.5, filed Dec. 7, 2012, which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a heat exchanger arrangement of a technical object whose temperature is to be controlled, in particular of a battery for an electric vehicle drive, having a flat heat exchanger which has an inflow and outflow duct and which is traversed by a flow of a heat carrier medium, which heat exchanger is in heat-conducting contact with internal surfaces of the object whose temperature is to be controlled. 
     2. Description of the Related Art 
     DE102006059989 discloses a heat exchanger arrangement in which a structured cooling plate formed by pressure die casting is in heat-conducting contact with a hose-like cooling pipe and with heat-conducting elements protruding from said cooling pipe, which heat-conducting elements are in superficial contact with round cells of a battery for an electric vehicle drive. 
     DE102010055616 discloses a further heat exchanger arrangement of said type in which a solid cooling plate, which has individual internal ducts traversed by flow, is screwed to multiple solid frames which serve for holding pouch-like battery cells. 
     Said known heat exchanger arrangements illustrate the relatively great outlay required in terms of construction for producing ducts for conducting a heat carrier medium through a heat exchanger of flat form, and for producing heat-conducting contact with internal surfaces of an object whose temperature is to be controlled. Furthermore, a heat exchanger of said type takes up a relatively large amount of space in a corresponding arrangement, such that said heat exchanger contributes significantly to the structural size of the arrangement. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of finding a thermally highly effective heat exchanger arrangement of the stated type which takes up a relatively small structural volume and which can be produced and assembled in a particularly simple manner and inexpensively as a mass-produced product. 
     Said object is achieved according to the invention in that the heat exchanger is in the form of a heat-exchanging pouch formed from foil material, and in that, parallel thereto, there is arranged a pressure pouch which is filled with a compressible medium and which is formed from a foil material. 
     It is self-evident that a heat-exchanging pouch of said type can, by contrast to the plate-shaped metallic cast bodies of the cited prior art, be produced in a simple manner by being cut out or punched out of foil pieces in accordance with their desired shape and size, by being arranged so as to lie one on top of the other, and by being welded or adhesively bonded in the region of their edges. As a result of the flexible contact of said heat-exchanging pouch with heat-conducting internal surfaces of the object whose temperature is to be controlled, under the pressure exerted by the pressure pouch, said heat-exchanging pouch is supported with its internal pressure against said internal surfaces and can consequently accommodate a high pressure and flow rate of a heat carrier medium flowing through, and thus ensure a high quality of a transfer of heat by forced convection. 
     A heat-exchanging pouch of said type, owing to its low material and space requirement in relation to the size of its heat exchanger surfaces, is suitable for being inserted together with the hitherto still unfilled pressure pouch into a relatively narrow gap space, such that the technical object whose temperature is to be controlled can be produced with a correspondingly small structural size. 
     After the pressure pouch is filled with air or nitrogen and sealingly closed off, the heat-exchanging pouch lies firmly, under the fill pressure of the pressure pocket, against an internal surface of the object whose temperature is to be controlled, such that good conduction of heat to said object is ensured. 
     For a uniform distribution of the pressure exerted by the pressure pouch within the technical object, such as for example within the housing of a battery, it is provided in a preferred embodiment of the invention that a pressure distribution plate is arranged between the pressure pouch and the heat-exchanging pouch. 
     In a further advantageous embodiment of the invention, for a uniform flow distribution between the foil walls, a flow-guiding grate is enclosed between the foil walls of the heat-exchanging pouch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantageous embodiments of the invention are specified in the dependent patent claims and emerge from the following description on the basis of the drawings, in which: 
         FIG. 1  is a perspective illustration of a heat-exchanging pouch of the heat exchanger arrangement according to the invention, with a sectional illustration in the region of an inflow connection, and a pouch wall being illustrated in partially cut-away form, 
         FIG. 2  is an enlarged, partially sectional illustration of the inflow region of the heat-exchanging pouch as per  FIG. 1 , 
         FIG. 3  shows a plan view of a part of the heat-exchanging pouch as per  FIG. 1  without a second foil wall and with the flow distribution being indicated by arrows, 
         FIG. 4  shows a partial cross section through a battery which has a heat exchanger arrangement according to the invention, 
         FIG. 5  is a perspective illustration of multiple interconnected heat exchanger arrangements in a battery, 
         FIG. 6  is a perspective illustration of the flow-guiding grate in a further embodiment of a heat-exchanging pouch, with connection nozzles formed integrally on said flow-guiding grate, 
         FIG. 7  shows a partial cross section through a heat-exchanging pouch in the region of one of its connection nozzles, 
         FIG. 8  shows an enlarged perspective partial illustration of the flow-guiding grate as per  FIG. 6 , in the region of a connection nozzle, and 
         FIG. 9  shows an enlarged partial section in the plane of the heat-exchanging pouch and in the region of dam nozzles. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The heat-exchanging pouch  1  of the heat exchanger arrangement according to the invention illustrated in  FIG. 4  is composed of two thin walls  2 ,  3  which run parallel to one another, which are formed from a foil material and which are sealingly connected to one another in the region of their edges  4 . 
     A suitable foil material for the production of the heat-exchanging pouch  1 , in order to optimize its characteristics with regard to tear resistance, material durability, thermal conductivity, electrical insulation and weldability, is composed of a layered composite of different materials, such as, for example aluminum, polyamide, and polypropylene, and is commercially available with a foil thickness of less than 0.2 mm for various applications. If used for the cooling of a battery, at least one of the outer layers of the foil material should be composed of an electrically insulating plastics material, in order to render the arrangement of an additional electrically insulating foil unnecessary. 
     The heat-exchanging pouch  1  has, for example, a rectangular form with rounded corner regions  5  and, in the area of two corner regions situated opposite one another at a narrow side, connection regions  6 ,  7  which project in approximately semicircular form and which serve for the laterally external arrangement and fastening of in each case one connection nozzle  8 ,  9 , oriented vertically with respect to the plane of the heat-exchanging pouch  1 , for the supply and discharge, and thus circulation, of a heat carrier medium through the heat-exchanging pouch  1 . 
     For the receiving and fastening of the connection nozzles  8 ,  9 , in each case one circular opening  10  is punched out in the connection region  6 ,  7  of one of the walls  2 ,  3  of the heat-exchanging pouch  1 . The wall region  11  surrounding said opening  10  bears, by way of its inner side, against a connecting flange  12  of the connection nozzle  8 ,  9  and is fixedly and sealingly connected to said connecting flange by welding or adhesive bonding. 
     In relation to the relatively small spacing between the walls  2 ,  3  of the heat-exchanging pouch  1 , which spacing permits an adequate flow through the heat-exchanging pouch  1  and is preferably less than 2 mm, it is thus possible for the inner diameter, through which flow passes, of the connection nozzles  8 ,  9  to be configured so as to be relatively large, such that a correspondingly high delivery flow rate of the heat carrier medium can be realized, and consequently a particularly effective exchange of heat can be realized, with low temperature differences, within the heat-exchanging pouch  1 . 
     For a flow distribution, which promotes the exchange of heat, of the flow through the heat-exchanging pouch  1  from the inflow connection nozzle  8  thereof to the outflow connection nozzle  9  thereof, a flow-guiding grate  13  is provided between the two walls  2 ,  3  of the heat-exchanging pouch  1 , which flow-guiding grate is composed of interconnected flow-guiding webs which delimit longitudinally and transversely oriented flow paths, as indicated by directional arrows in  FIG. 3 . 
     In the illustrated exemplary embodiment, an inner grate composed of numerous, mutually parallel transverse webs  14  delimits transverse ducts  15 ,  16  which branch off from at least one inflow duct  17 ,  18  guided along the longitudinal edges of the heat-exchanging pouch  1  and which issue into at least one outflow duct  19 ,  20  guided along the opposite longitudinal edge. 
     A longitudinal web  21  which connects the transverse webs  14  to one another at their ends in ladder-shaped form has a smaller cross-sectional height than said transverse webs, such that those regions of the longitudinal web which extend between the transverse webs  14  form in each case one dam web  22 . Consequently, the dam webs  22  generate a more uniform flow distribution through the transverse ducts  15  and  16  from the inflow duct  16  to the outflow duct  19 ,  20 . 
     Furthermore, for uniform flow distribution, in each case one flow-dividing longitudinal web  25 ,  26  is provided which runs at least approximately parallel to the longitudinal edges  23 ,  24  of the heat-exchanging pouch  1  and which, in its outflow-side region, merges via a curvature  27 ,  28  into a dividing web  29 . Said dividing web  29  delimits two groups of transverse ducts  15 , on the one hand, and  16 , on the other hand, from one another. 
     A flow-guiding grate  13  preferably designed in the described way can, in an inexpensive manner, be produced as an injection-molded part, for example from an aluminum alloy or from plastic, and, during the production of the heat-exchanging pouch  1 , be placed between the foil walls  2 ,  3  of said pouch before said foil walls are welded to one another along the pocket edges  4 . The flow-guiding grate  13  consequently forms, by way of its webs  14 ,  25 - 27  which are of equal height in cross section, an internal support which defines the distance of for example 2 mm between the pouch walls  2 ,  3 . Such a support can absorb the areal pressure required for stable cohesion, for example of the components of a battery for a vehicle drive. 
     The illustration of  FIG. 4  shows an exemplary embodiment which serves for controlling the temperature of numerous bar cells  30 , which are arranged parallel to one another in the same plane and which are electrically connected to one another in parallel and in series, of a battery  31  for a vehicle drive. The heat conduction from the bar cells  30  to the heat-exchanging pouch  1  takes place here preferably via the end-side electrical contacts  32  thereof, for which purpose these are electrically connected to one another in parallel by means of a common contact plate  33 , and the heat-exchanging pouch  1  bears in heat-conducting fashion against said contact plate  33 . 
     In order that the heat-exchanging pouch  1  is pressed uniformly against the contact plate  33  and thus good heat-conducting contact is obtained and uniform pressure loading of the flow-guiding grate  13  enclosed therein is realized, a pressure pouch  34  is provided which is filled with a compressible medium, such as for example air or nitrogen, and a pressure distribution plate  35  provided between said pressure pouch and the heat-exchanging pouch  1  ensures a uniform transmission of pressure to the bar cells  30 . In this way, it is ensured that said bar cells are provided with good temperature control and are held in a vibration-proof manner. Here, the pressure pouch  34  is supported, by way of its side averted from the heat-exchanging pouch  1 , against the inner surface  36  of a wall  37  of a closed battery housing (not illustrated). 
       FIG. 5  shows an exemplary application of the invention for controlling the temperature of electrical bar cells  30  grouped in compact fashion in multiple layers  38 - 41  arranged one on top of the other, wherein in each case one heat-exchanging pouch  1  is provided between each mutually adjacent layer and also at the outside on the outer layers  38 ,  41 . Consequently, the control of the temperature of the bar cells  31  is realized via a heat-conducting connection to the two contact ends thereof. 
     The connection nozzles  8 ,  9  provided on each of the mutually parallel heat-exchanging pouches  1  are provided one above the other on the same axis in the region of a face-end side surface  42  of the battery  31 , and are connected via a T-shaped branch  43  or 90° elbow  44  to a common connection line  45 ,  46  running parallel to said side surface. Said connection lines  45 ,  46  form, via connection nozzles  47 ,  48  provided thereon, a connection to a circulation pump (not illustrated) and to an external heat exchanger (not illustrated). 
     When the battery  31 , which includes for example lithium-ion cells, is under electrical load, the heat exchanger serves to dissipate the heat thereby generated in the battery cells  30 . 
     A cooling action which may be detrimental to the battery cells  30  and to the performance thereof for example during operation in winter can preferably be prevented, in combination with a thermal insulation  49  of the battery, by means of a heating body  50  which is fastened to one of the connection lines  45 ,  46  and which is for example electrically operated by means of a thermostat switch. 
     In a second exemplary embodiment of a heat-exchanging pouch, the foil walls  51 ,  52  thereof including the edges of said foil walls are welded or adhesively bonded onto an inner supporting frame  53  which also serves as a flow-guiding grate, for which purpose said inner supporting frame additionally has an outer frame  54 , which corresponds in terms of its size to the outer contour of the heat-exchanging pouch, and transverse webs  56 , which delimit transverse flow ducts  55  and whose cross-sectional height corresponds to that of the outer frame  54 . By contrast, the webs which extend outward as a continuation of the transverse webs  56  and transversely with respect to the longitudinal ducts  57 ,  58  form ridge-like dam webs  59 . 
     To obtain a uniform flow through the heat-exchanging pouch by means of flow damming even in the case of the transverse flow running through the transverse flow ducts  55 , it is provided that, corresponding to the illustrations in  FIG. 8  and  FIG. 9 , in each case one row of rounded dam bodies  61  connected to one another by means of a web  60  is provided at the inflow side and at the outflow side, such that said dam bodies between them form a row of dam nozzles  62 . The height of said dam nozzles  62  corresponds to that of the transverse webs  56  and of the outer frame  54 . Consequently, the foil walls  51 ,  52  may additionally also be welded or adhesively bonded to said rows of dam bodies  61 . 
     The connection nozzles  63 ,  64  of the heat-exchanging pouch may be integrally formed on the supporting frame  53  which is formed as a plastics injection-molded part. For this purpose, a trough-shaped duct piece  65  is formed between the planar supporting frame  53  and the cylindrical connection nozzles  63 ,  64 , such that the edge  66  of said duct piece merges into the outer frame  54  in the same plane as the latter. 
     To stiffen the transition region between the two trough-shaped duct pieces  65  and the two connection pieces  63 ,  64 , a rib  67  which extends in the flow direction and which thus also guides the flow may be formed on said transition region. 
     LIST OF REFERENCE SIGNS 
     
         
           1  Heat-exchanging pouch 
           2 ,  3  Thin walls 
           4  Edges 
           5  Corner region 
           6 ,  7  Connection regions 
           8 ,  9  Connection nozzles 
           10  Circular foil opening 
           11  Surrounding wall region 
           12  Connecting flange 
           13  Flow-guiding grate 
           14  Transverse webs 
           15 ,  16  Transverse ducts 
           17 ,  18  Inflow duct 
           19 ,  20  Outflow duct 
           21  Longitudinal web 
           22  Dam web 
           23 ,  24  Longitudinal edges 
           25 ,  26  Longitudinal web 
           27 ,  28  Curvature 
           29  Dividing web 
           30  Bar cell 
           31  Battery 
           32  Electrical contacts 
           33  Contact plate 
           34  Pressure pocket 
           35  Pressure distribution plate 
           36  Inner surface 
           37  Wall of the battery housing 
           38 - 41  Layers of bar cells 
           42  Side surface 
           43  T-branch 
           44  Elbow 
           45 ,  46  Connection lines 
           47 ,  48  Connection nozzles 
           49  Insulation 
           50  Heating body