Abstract:
At least one power semiconductor component is cooled by a flat, copper, plate-type hollow body conducting a coolant fluid. Components are fixed on one flat-sided surface of the hollow body and the other flat-sided surface includes two coolant fluid openings for introducing the coolant fluid into the hollow body and for evacuating the fluid therefrom. The other flat-sided surface is concave and elastically deformable between the coolant fluid openings. The concave other surface is attached to the even surface of a support in such a way that the concave surface and the even surface are pressed against each other by the elastically planar deformation of the concave surface and that the coolant fluid openings are sealed in a fluidproof manner by O-rings. A solid strut, which interconnects the two flat-sided surfaces is additionally configured in the hollow body. The cooling device may be used in a module or an assembly including a support and the cooling device or module. The device is useful in electric transmissions, in particular, in motor vehicles.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on and hereby claims priority to PCT Application No. PCT/DE03/01498 filed on 9 May 2003, the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a cooling device for cooling one or more electrical components, a module including such a cooling device and electrical components fixed to it, an arrangement including such a cooling device and of a support and an arrangement including such a module and such a support.  
         [0004]     2. Description of the Related Art  
         [0005]     A cooling device of the type named is known from U.S. Pat. No. 6,014,312. This known cooling device has a hollow body for conducting the coolant fluid between two flat-sided surfaces of the hollow body, facing away from each other, that include several layers of metal stacked one on the other, that are joined flat to each other and each of which has a number of small openings that overlap from layer to layer and form passages for the coolant fluid through the layered stack.  
         [0006]     In each layer there are also two large openings between which the small openings of this layer are arranged. The large openings are arranged one above the other in the layered stack and thus form two coolant fluid collecting cavities in the hollow body between the even flat-sided surfaces of the hollow body that are faced away from each other and defined by closed outer layers of the layered stack.  
         [0007]     Each of the electrical components to be cooled is to be fixed, insulated from the coolant fluid in the hollow body by a layer of ceramic material that has good heat conducting and electrically insulating properties, to one of the two flat-sided surfaces of the hollow body. The ceramic layer can be placed on a flat-sided surface of the hollow body or arranged between two of the layers of metal of the hollow body.  
         [0008]     A coolant fluid opening for supplying and removing the coolant fluid in or out of this coolant fluid collecting cavity is assigned to each of the two coolant fluid collecting cavities, that are formed in the otherwise also-closed, other even flat-sided surface of the hollow body. Each coolant fluid collecting cavity has a larger diameter than the coolant fluid opening assigned to it.  
         [0009]     The hollow body is to be fixed to an even surfaces of a support in such a way that the even other flat-sided surface of the hollow body and the even surface of the support are facing toward each other and form a flat surface contact with each other.  
         [0010]     The support can be a plate or a structure including a number of coolant fluid channels distributed over the complete support for supplying and removing coolant fluid.  
       SUMMARY OF THE INVENTION  
       [0011]     An object of the invention is to provide an improved coolant fluid conductance with a cooling device of the type mentioned in the introduction.  
         [0012]     An improved coolant fluid conductance with a cooling device of the type mentioned can be obtained in accordance with the invention in which 
        the other flat-sided surface of the hollow body between the coolant fluid openings is concave and elastically deformable, and that     a fixing or attachment device is provided for fixing or attaching the hollow body to the even surface of the support in such a way that the concave other flat-sided surface of the hollow body and the even surface of the support are pressed together with an elastic planar deformation of the concave other flat-sided surface of the hollow body.        
 
         [0015]     The cooling device has the advantage that it can be fixed to an even surface of a support in a simple manner, that does not require a structure including a number of coolant fluid channels distributed over the complete support, but instead advantageously has only a single coolant fluid channel for each coolant fluid opening of the cooling device for the supply or removal of the coolant fluid to and from this coolant fluid opening, with additionally having the particular advantage that this coolant fluid opening and this coolant fluid channel can be simply and easily sealed against coolant fluid leakage to the environment during the operation of fixing the cooling device to the support, by a common O-ring alone.  
         [0016]     Because the coolant, fluid therefore can advantageously be supplied through a single coolant fluid channel in the support to the assigned coolant fluid opening of the cooling device, or removed from same, and such a channel can be simply produced. For example, a coolant fluid channel of this kind can be formed by drilling a through-hole in the support.  
         [0017]     To fix the cooling device all that is required is that 
        the support has an even surface in which, for each coolant fluid opening in the concave other flat-sided surface of the hollow body of the cooling device, there is a termination of a coolant fluid channel, formed in the support for the supply or removal of coolant fluid, that is assigned in each case to one of these coolant fluid openings, that     the even surface of the support and the concave other flat-sided surface of the hollow body of the cooling device are faced towards each other and arranged in such a way that the termination of the support assigned to this coolant fluid opening is opposite each coolant fluid opening of the cooling device, whereby     O-rings of resilient material are arranged between these surfaces of the support and the cooling device facing towards each other, each of which encloses a coolant fluid opening of the cooling device and the termination of the fluid channel of the support opposite this coolant fluid opening, and that     the cooling device and the support are fixed to each other by the fixing device of the cooling device in such a way that the concave other flat-sided surface of the hollow body of the cooling device is elastically pressed flat and each O-ring is compressed between this flat-pressed surface and the even surface of the support is compressed so that it seals the coolant fluid opening of the cooling device and the termination of the coolant fluid channel of the support opposite this coolant fluid opening, both of which are enclosed by this O-ring and provide a fluid-proof seal against the environment.        
 
         [0022]     With this simple fixing procedure, each coolant fluid opening of the cooling device and the termination of the coolant fluid channel opposite this coolant fluid opening are automatically provided with a fluid-proof seal against the environment and a particularly simple coolant fluid conductance is advantageously realized.  
         [0023]     The concave flat-sided other surface of the hollow body is an essential condition for the realizability of the simple fixing of the coolant fluid device to the support, because only with it can a force sufficient to compress the O-rings arranged at the coolant fluid openings be exerted. An elastically deformable, even flat-sided other surface of the hollow body would undergo a similar convex deformation and therefore would detrimentally rather release than stress an O-ring. The fixing device of the cooling device can advantageously be realized in a simple manner by at least one threaded hole formed between the two coolant fluid openings, 
        that has a fluid-proof seal against the coolant fluid in the hollow body, so that no coolant fluid can leak from the hollow body through this threaded hole, and     that in the concave other flat-sided surface of the hollow body a threaded-hole opening is provided through which a threaded pin passing through the support is screwed into the threaded hole in order to secure the cooling device and support to each other.        
 
         [0026]     By screwing the threaded pin into the threaded hole, the concave flat-sided other surface of the hollow body opposite the even surface of the support can be pulled onto the support and pressed flat against it.  
         [0027]     In a preferable and advantageous manner, the fixing device has two threaded holes formed in the hollow body between the two coolant fluid openings, 
        each of which has a fluid-proof seal against the coolant fluid in the hollow body so that no coolant fluid can leak from the hollow body through this threaded hole and     each of which has a threaded hole opening in the concave other flat-sided surface of the hollow body through which a threaded pin passing through the support is screwed into the threaded hole, to secure the cooling device and support to each other.        
 
         [0030]     In this way, a particularly strong pressure can be exerted on the O-rings and thus a particularly reliable sealing effect can be achieved by the O-rings, in particular if one threaded hole is placed close to one coolant fluid opening and the other threaded hole is placed close to the other coolant fluid opening of the cooling device.  
         [0031]     For the threaded pins, the support requires only through-holes at the points of the threaded holes in the hollow body of the cooling device. A through-hole of this kind can, for example, again be a simple hole through which the threaded pin can be pushed or screwed.  
         [0032]     An improved coolant fluid conductance can be obtained with a cooling device of the type mentioned in the introduction, in which 
        a coolant fluid guide is formed in the hollow body between the coolant fluid openings, that guides the coolant fluid introduced through a coolant fluid opening in the hollow body sideways in the hollow body, past the center, between the coolant fluid openings of the hollow body to the other coolant fluid opening.        
 
         [0034]     By this means, a better fluid guidance in the hollow body concentrated on the components to be cooled can advantageously be achieved and therefore a better cooling effect obtained for these components. Components not to be cooled, for example busbars, that become less hot, can advantageously be secured above the coolant fluid-free center of the hollow body to the one flat-sided surface.  
         [0035]     The coolant fluid guide requires at least one deflecting surface arranged close to the coolant fluid opening, that deflects the coolant fluid passing through this coolant fluid opening and prevents a direct flow of the inlet coolant fluid from this coolant fluid opening to the other coolant fluid opening, i.e. prevents a flow through the center between the two coolant fluid openings. A deflecting surface of this kind can be realized in various ways.  
         [0036]     With a preferred and advantageous form of the embodiment of the cooling device, the coolant fluid guide has a solid strut of material with good heat conducting properties formed in the center of the hollow body, 
        that connects the two flat-sided surfaces of the hollow body to each other,     that does not permit the passage of the coolant fluid,     that is formed along the connecting line between the two coolant fluid openings and     along the side of which coolant fluid introduced through a coolant fluid opening in the hollow body flows in the hollow body to the other coolant fluid opening.        
 
         [0041]     With this form of embodiment, the deflecting surface of the coolant fluid guide can be simply realized by a front face of the strut, that is opposite a coolant fluid opening through which the coolant fluid is supplied. Because of the shape of this front end, the deflecting surface can be chosen as required to suit individual cases. For example, this free end can be in the form of a prism-shaped pointed end of the strut.  
         [0042]     In a preferred and advantageous embodiment of this form of the invention, the strut has a front end that is opposite a coolant fluid opening and is rounded.  
         [0043]     The solid strut advantageously also acts as an additional heat sink and improves the cooling effect of the cooling device.  
         [0044]     One threaded hole of the hollow body is advantageously placed in the strut.  
         [0045]     The coolant fluid guide can have a clearance from one edge of the coolant fluid opening or extend to the edge of a coolant fluid opening.  
         [0046]     It is generally advantageous if a structure made of material with good heat conducting properties is formed in the hollow body, through which structure the coolant fluid can flow, that offers the flowing coolant fluid an increased contact surface and that is in a good heat-conducting contact with the flat-sided surfaces of the hollow body.  
         [0047]     A structure of this kind improves the heat dissipation and therefore the cooling effect of the cooling device and can be realized in a variety of ways, for example by a lattice and/or an interlinked fabric and/or a sponge.  
         [0048]     Advantageously, the structure of good heat-conducting material has small cavities, each of which is enclosed by this material and in connection with each other, and/or small channels, each of which is enclosed by this material and connects the two coolant fluid openings to each other.  
         [0049]     Such structures for example include a grid or a sponge derived from the structures in the named U.S. Pat. No. 6,014,312 etc.  
         [0050]     In particular, the hollow body can have a cooling device in accordance with the invention such as a cooler according to the U.S. Pat. No. 6,014,312 with a layered stack including layers of good heat-conducting material provided with small holes, whereby the holes are offset from layer to layer, but do overlap. With this type of structure, a solid strut in the hollow body can be realized simply by areas of the layers that are without holes that lie one above the other in the stack. The structure of good heat-conducting material with the cooling device in accordance with the invention advantageously extends up to one edge of a coolant fluid opening, in contrast to a cooler according to U.S. Pat. No. 6,014,312. The structure in this case can enclose the edge of the coolant fluid opening, or can extend only along a part section of this edge but not over the complete edge, particularly if a coolant fluid guide extends up to the edge of this coolant fluid opening.  
         [0051]     A particularly preferred form of embodiment of a cooling device in accordance with the invention can be formed whereby 
        the hollow body can be made of electrically conducting material and     the electrical component(s) fixed to the cooling device is/are electrically insulated from the coolant fluid in the hollow body by a layer of good heat-conducting and electrically-insulating material, that is parallel to a flat-sided surface of the hollow body and is fixed to the hollow body.        
 
         [0054]     The layer of good heat-conducting, electrically-insulating material is preferably placed on the one flat-sided surface of the hollow body of the cooling device and can, where the hollow body has a stack of layers of electrically-conducing material, also be arranged between two such layers.  
         [0055]     A layer of electrically-conducting material arranged on the side of the layer of heat-conducting and electrically-insulating material facing away from the hollow body, whether it is a layer of the stack or a layer of electrically-conducting material fitted afterwards, is preferably structured, for example to form electrical conductors, that in the case of electrical components to be cooled that are in the form of power semiconductor components can be busbars.  
         [0056]     The layer of electrically-conducting material can extend over the complete surface of the complete hollow body. Because of the problems that can result from different thermal coefficients of expansion between the electrically-conducting material of the hollow body and the material of the electrically-insulating layer, and for example cause delamination of the electrically-conducting layer from the hollow body, it can be advantageous if the layer of good heat-conducting material and electrically-insulating material is arranged in sections separate from each other.  
         [0057]     The layer of good heat-conducting and electrically-insulating material is preferably of a ceramic material and the electrically-conducting material of the hollow body is preferably made of copper.  
         [0058]     It is of particular advantage if the layer of good heat-conducting and electrically-insulating material attached to the hollow body has a lower coefficient of thermal expansion than the hollow body.  
         [0059]     This measure advantageously results in a particularly simple method of manufacturing the cooling device in accordance with the invention with the hollow body that has the elastically deformable concave other flat-sided surface.  
         [0060]     This method consists simply in that the layer of good heat-conducting and electrically-insulating material is firmly fixed to the hollow body at higher temperature and the layer and hollow body are subsequently cooled down. During the cooling, the material of the hollow body contracts more than the material of the electrically-insulating layer and because of this “bimetal effect” itself creates the elastically deformable concave other flat-sided surface of the hollow body.  
         [0061]     For example, an electrically-insulating layer coated with metal is soldered to a flat-sided metal surface of the hollow body. During the soldering operation, the layer and the hollow body heat up and expand at different rates, i.e. the hollow body at a greater rate than the layer. As the solder solidifies, the hollow body and the layer join together while the temperature is still high. During the subsequent cooling, the hollow body contracts more than the layer connected to it, so that after cooling the other flat-sided surface of the hollow body itself becomes concave and can be elastically deformed.  
         [0062]     Up to now this “bimorph or bimetal effect” was a disturbing effect and attempts were made to avoid it, for example to achieve flat-sided surfaces of the hollow body, e.g. by using an electrically insulating layer of the same material in each case on each flat-sided surface of the hollow body. The invention has departed from this and deliberately utilizes the “bimorph or bimetal effect”. The “bimorph or bimetal effect” can advantageously be used regardless of whether the hollow body has a coolant fluid guide, particularly a solid strut, or not.  
         [0063]     A cooling devices in accordance with the invention can be used in a novel type of module with a cooling device of this kind and one or more electrical components that are attached to the one flat-sided surface of the hollow body of the cooling device is created.  
         [0064]     This module can advantageously be equally simply secured to the support with the aid of O-rings, as described above with regard to the cooling device alone without electrical components.  
         [0065]     In concrete terms, this means that for a module of this kind 
        a support is used that has an even surface in which for each coolant fluid opening in the concave other flat-sided surface of the hollow body of the cooling device of the module a termination of a coolant fluid channel formed in the support for the supply or removal of coolant fluid is assigned to one of these coolant fluid openings in each case, that     the even surface of the support and the concave other flat-sided surface of the hollow body of the cooling device of the module are faced towards each other and arranged in such a way that each coolant fluid opening of the cooling device of the module is opposite the termination of the fluid channel of the support assigned to this coolant fluid opening, whereby     between these surface of the support and cooling device of the module facing toward each other, O-rings of elastic material are arranged, each of which encloses a coolant fluid opening of the cooling device of the module and the termination of the support opposite this coolant fluid opening, that     the cooling device and the support are secured to each other by the fixing device of the cooling device in such a way that the concave other flat-sided surface of hollow body of the cooling device of the module is elastically pressed flat and each O-ring is compressed between this flat-pressed surface and the even surface of the support, so that it seals the coolant fluid opening of the cooling device of the module and the termination of the coolant fluid channel of the support opposite this coolant fluid opening, both of which are enclosed by this O-ring, to provide a fluid-proof seal against the environment.        
 
         [0070]     The module can advantageously also be realized by 
        a cooling device that has a coolant fluid guide, and with     one or more electrical components that are secured to the one flat-sided surface of the hollow body of the cooling device, whereby     the attached component(s) is/are arranged near the coolant fluid guide in the area of the coolant fluid flowing between the coolant fluid opening of the hollow body past the center to the other coolant fluid opening.        
 
         [0074]     In a preferred and advantageous manner with this module, electrical components that generate different amounts of heat in operation are arranged in succession in the direction of flow of the cooling fluid flowing past the center between the cooling fluid openings of the hollow body to the other coolant fluid opening in such a way that a component that generates a relatively smaller amount of heat is followed by a component that generates a relatively greater amount of heat.  
         [0075]     It is also again advantageous if electrical components that generate different amounts of heat from each other in operation are arranged in succession in the direction of flow of the coolant fluid flowing past the center between the coolant fluid openings of the hollow body to the other coolant fluid opening in such a way that a component that generates a relatively greater amount of heat is followed by a component that generates a relatively smaller amount of heat. This means particularly that components that generate a relatively greater amount of heat should be arranged on the inside and components that generate a relatively smaller amount of heat should be arranged on the outside.  
         [0076]     Generally, an aforementioned module is preferably a power semiconductor module, i.e. at least one electrical component of this module is a power semiconductor element.  
         [0077]     The invention has the advantage of simplicity of manufacture and an extremely flat construction.  
         [0078]     In an embodiment of the invention, the support is part of an electrical transmission system.  
         [0079]     With a special preferred form of an embodiment, the support is part of an electrical transmission system for a vehicle.  
         [0080]     Water is preferred as the coolant fluid but other fluids, such as oil, can also be used.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0081]     These and other objects and advantages of the present invention will become more apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0082]      FIG. 1  is a perspective drawing of a power semiconductor module that is used in the invention.  
         [0083]      FIG. 2  is a vertical lengthwise section of the module according to  FIG. 1 , lengthwise along cut line II-II in  FIG. 1 .  
         [0084]      FIG. 3   a  is a vertical cross-section through the module according to  FIG. 1 , shown lengthwise along the cut line III-III in  FIG. 1 .  
         [0085]      FIG. 3   b  is the bottom part of the vertical cross-section according to  FIG. 3   a , that in contrast to  FIG. 3   a  shows a concave other flat-sided surface of the hollow body of the module.  
         [0086]      FIG. 4  is a horizontal section through the module in  FIG. 1  taken along the cut line IV-IV in  FIG. 1 .  
         [0087]      FIG. 5  is the top part of the vertical longitudinal section according to  FIG. 2 , that in contrast to  FIG. 2  shows a subdivided layer of good heat-conducting, electrically-insulating material.  
         [0088]      FIG. 6  is an enlarged view of the part of  FIG. 3   a  bounded by the circle B.  
         [0089]      FIG. 7  is a section view according to  FIG. 2  showing an arrangement including a module and support that at the same time shows an arrangement including a cooling device and the support, with only part of the support illustrated. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0090]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.  
         [0091]     The power semiconductor module shown in  FIG. 1  and generally designed by  1 ′ has an example of a cooling device  1  according to the invention and an arrangement  2  including several electrical components in the form of power semiconductor elements  20  and  20 ′ to be cooled, each of which is fixed to one of two flat-sided surfaces  101  and  102 , facing away from each other, of an essentially flat plate-shaped hollow body  10  of the cooling device  1 , made of material, such as copper, with good heat-conducting properties.  
         [0092]     The following is a general unrestricted assumption that the power semiconductor elements  20  and  20 ′ are fixed to the flat-sided surface  101  of the hollow body  10 , so that the surface  101  forms the one flat-sided surface and the surface  102  forms the other flat-sided surface of the hollow body  10 .  
         [0093]     The power semiconductor elements  20  and  20 ′ could equally well be fixed to surface  102 , so that surface  102  would be the one flat-sided surface and surface  101  the other flat-sided surface of the hollow body  10 .  
         [0094]     The hollow body  10  used to provide a passage for a coolant fluid  3  (shown in  FIGS. 2 and 4  by thick arrows, the heads of which indicate the direction of flow of the coolant fluid) through the hollow body  10  between its two flat-sided surfaces  101  and  102 . The coolant fluid  3  consists, for example, of water.  
         [0095]     The hollow body  10  is formed as a flat plate shape and essentially is of rectangular form with a central longitudinal axis A.  
         [0096]     The arrangement  2  of the power semiconductor elements  20  and  20 ′ is not fixed directly to the essentially-rectangular one flat-sided surface  101  of the hollow body  10 , but instead to a surface  180 , facing away from the hollow body  10 , of an essentially rectangular layer  18  of good heat-conducting, electrically-insulating ceramic material that is positioned on the one flat-sided surface  101  of the hollow body  10  and soldered to it. The arrangement  2  is electrically insulated from the hollow body  10  by this electrically-insulating layer  18 .  
         [0097]     In addition to the arrangement  2  including the power semiconductor elements  20  and  20 ′ to be cooled, electrical components not to be cooled, such as busbars  21 , are also for example secured to the surface  180  of the electrically-insulating layer  18 .  
         [0098]     For a further explanation of the construction of the cooling device  1  or of the module  1 ′, refer to FIGS.  2  to  4 . For clarity, these figures omit the electrical components  20 ,  20 ′,  21  of the module  1 ′, where they would actually be visible.  
         [0099]     As shown in these figures, two coolant fluid openings  11  for supply or removal of the coolant fluid  3  to and from the hollow body  10  are formed spaced apart in the other flat-sided surface  102  of the hollow body  10  of the cooling device  1  or the module  1 ′.  
         [0100]     As described in more detail later in  FIG. 7 , the hollow body  10  is fixed to an even surface  41  of a support  4  in such a way that the other flat-sided surface  102  of the hollow body  10  and the even surface  41  of the support  4  are faced towards each other.  
         [0101]     In accordance with the invention, the other flat-sided surface  102  of the hollow body  10  between the fluid openings  11  is concave and elastically deformable and a fixing device  5  for fixing the hollow body  10  to the even surface  41  of the support  4  is provided in such a way that the concave other flat-sided surface  102  of the hollow body  10  and the even surface  41  of the support  4  are pressed against each other by the elastically planar deformation of the concave other flat-sided surface  102  of the hollow body  10 .  
         [0102]     The other flat-sided surface  102  of the hollow body  10  is predominantly curved in the direction of the longitudinal axis A of the hollow body  10  and can, additionally or alternatively, also be curved in the direction of the III-III or IV-IV perpendicular to longitudinal axis A in  FIG. 1 , as indicated in  FIG. 3   b.    
         [0103]     The fixing device  5  has, for example two internally-threaded holes  12  in the hollow body  10  between the two coolant fluid openings  11 , each of which is sealed against the coolant fluid  3  in the hollow body  10  forming a fluid-proof seal, so that no coolant fluid  3  can flow through this threaded hole  12  out of the hollow body  10  to the outside and each of which has a threaded hole  120  in the concave other flat-sided surface  102  of the hollow body  10 , through which an externally-threaded pin  13  passing through the support  4  is screwed into the threaded hole  12  to secure the cooling device  1  or module  1 ′ and support  4  to each other.  
         [0104]     Preferably, the threaded holes  12  are arranged on the longitudinal axis A of the hollow body  10  close to a coolant fluid opening  11  in each case.  
         [0105]     Each threaded hole  12  is, for example, provided with an internally threaded bush  121  of a material that is harder that the material of the hollow body  10  and is inserted into the hollow body  10 .  
         [0106]     In the example shown, each threaded hole  12  is a through-hole that passes transversely through the complete hollow body  10  and also has a threaded opening in the one flat-sided surface  101  of the hollow body  10 . A threaded hole  12  can also be a blind hole that only has the threaded hole opening  120  in the other flat-sided surface  102  of the hollow body  10  and no opening in the one flat-sided surface  101  of the hollow body  10 .  
         [0107]     In accordance with the invention, a coolant fluid guide  6  is also formed between the coolant fluid openings  11 , that guides the coolant fluid  3  supplied through a coolant fluid opening  11  to the hollow body  10  sideways in the hollow body  10  past the center  110  between the coolant fluid openings  11  of the hollow body  10  to the other coolant fluid opening  11 .  
         [0108]     The coolant guide  6  is preferably designed so that it is a solid strut  60  of good heat-conducting material that is formed centrally in the hollow body  10  and that joins the two flat-sided surfaces  101  and  102  of the hollow body  10  to each other, that is impermeable with regard to the coolant fluid  3 , that extends along a connecting line  111  (see  FIG. 2 ) between the two coolant fluid openings  11  and along both long sides  62  of which the coolant fluid  3 , introduced through a coolant fluid opening  11  into the hollow body  10 , flows in the hollow body  10  to the other coolant opening  11 .  
         [0109]     The strut  60  has a front end  61  opposite each coolant fluid opening  11 . The front end  61  of the strut  60 , that is opposite the coolant fluid opening  11  and adjacent to it, through which the coolant fluid  3  is introduced into the hollow body  10  and, for example, is the left coolant fluid opening  11  shown in  FIGS. 2 and 4 , defines a deflection surface for deflecting the coolant fluid  3  introduced into the hollow body  10 . This deflecting surface is preferably defined by a rounding  610  of this front end  61 .  
         [0110]     Preferably, the strut  60  shown in  FIG. 4  is, relative to the center  110 , formed as an essentially symmetrical mirror image between the coolant fluid openings  11  of the hollow body, so that also the other front end  61  of the strut  60 , that in the example is positioned opposite the right coolant fluid opening  11  for removing the coolant fluid  3  from the hollow body, has a rounding  610 .  
         [0111]     Instead of a rounding  610 , a different, for example pointed, shape can be chosen.  
         [0112]     The front ends  61  of the strut  60  are, for example, arranged at a distance from the coolant fluid openings  11 . It can also be designed so that one or each the front end  61  of the strut  60  extends to the edge  112  of a coolant fluid opening  11 .  
         [0113]     The threaded holes  12  of the hollow body  10  are preferably arranged in the strut  60  and preferably close to the front ends  61  of the strut  60 . If the material of this strut  60  is sufficiently hard, the insertion of internally-threaded bushes  121  can be omitted and a threaded hole  12  with an internal thread can be introduced directly in the strut  60 . Both measures ensure that the threaded hole  12  is fluid-proof, i.e. no fluid  3  can leak through the threaded hole  12  from the inside of the hollow body  10  to the outside.  
         [0114]     In the hollow body  10 , a structure  17  of good heat-conducting material, through which the coolant fluid  3  can flow, is formed that offers the flowing coolant fluid  3  an increased contact area and is in good heat-conducting contact with the flat-sided surfaces  101  and  102  of the hollow body  10  and with the strut  60 .  
         [0115]     The structure  17  of good heating-conducting material is preferably designed in such a way that it has small cavities  171 , each of which is enclosed by this material and that are in connection with each other and/or have small channels  172 , each of which is enclosed by this material and that connect both coolant fluid openings  11  with each other.  
         [0116]     The structure  17  can thus, the same as the corresponding structure from the named U.S. Pat. No. 6,014,312, be produced by a stack of layers, each with a number of small holes, whereby, in contrast to the U.S. patent, with this structure  17  the layers in the area of the strut  60  may not have any holes. The solid strut  60  in this case advantageously itself forms hole-free areas of the layers due to the stacking arrangement.  
         [0117]     The structure  17  can also, for example, be formed by filling a cavity of the hollow body  10  surrounding an already present solid strut  60  with lattice material and/or interlinked fabric and/or a sponge of good heat-conducting material, that is in close heat-conducting contact with the flat-sided surfaces  101  and  102  of the hollow body  10  and the solid strut  60 .  
         [0118]     Also, in contrast to the named U.S. Pat. No. 6,014,312, the structure  17  preferably extends from the good heat-conducting material to the edge  112  of a coolant fluid opening  11 . Because the front ends  61  of the strut  60  do not, for example, reach to the edge  112  of the coolant fluid openings, the structure  17  extending to the edge  112  of a coolant fluid opening  11  can even advantageously enclose this edge.  
         [0119]     In a case where a front end  61  of the strut  60  extends to the edge  112  of a coolant fluid opening  11 , the structure  17  extending to this edge  112  can, of course, not form a surrounding closure at this edge  112 , but instead can only extend over a part section of this edge  112 .  
         [0120]     With the example of an embodiment of the cooling device  1  or of the module  1 ′ shown in FIGS.  1  to  4 , the layer  18  of good-heating conducting and electrically-insulating material is placed completely flat on the hollow body  10  and secured to it.  
         [0121]     For this purpose, for example (see  FIG. 6 ), an electrically-insulating layer  18  coated with a metal layer  108  on the surface  181  (facing away from the surface  180  of the electrically-conducting layer  18  and facing towards the hollow body) of this layer  18  is soldered  109  to the one flat-sided surface  101  of the hollow body  10 .  
         [0122]     In the present example, the electrically-insulating layer  18  has a relatively smaller thermal coefficient of expansion α 1  and the hollow body  10  has a relatively larger thermal coefficient of expansion α 2 . During soldering, the electrically-insulating layer  18  and the hollow body  10  heat up and expand at different rates, the hollow body  10  more than the layer  18 .  
         [0123]     As the liquid solder  109  solidifies, the hollow body  10  and layer  18  join together at the still high temperature. During the succeeding cooling, the hollow body  10  contracts more than the layer  18  joined to it, so that after cooling the other flat-sided surface  102  of the hollow body becomes concave on its own and can be elastically deformed.  
         [0124]     Because of the stresses existing between the electrically-insulating layer  18  and the hollow body  10  during the later fixing to the support  4 , there is a certain tendency for the layer  18  to detach from the hollow body  10 . This can be reduced if the layer  18  of good heat-conducting, electrically-insulating material is divided into separate sections  18 ′, as shown in  FIG. 18 .  
         [0125]     With a concrete example of a cooling device  1 , already described, that does not limit the protective scope of the invention, that is used for a power semiconductor module  1 ′ as shown in  FIG. 1 , the hollow body  10  of copper is approximately 100 mm long, approximately 60 mm wide, approximately 3.5 mm thick and consists of a stack of copper layers. The coolant fluid openings  11  arranged on the longitudinal axis A symmetrically to the center  110  are spaced approximately 85 mm apart and each have an opening diameter of approximately 5.5 mm. The threaded holes  12  also arranged on the longitudinal axis A symmetrical to the center  110  are spaced approximately 65 mm apart and each has an opening diameter of approximately 4 mm. The soldered electrically-insulating layer  18 , that is not subdivided and essentially extends over the complete rectangular one flat-sided surface  101  of the hollow body  10 , consists of Al 2 0 3  and is approximately 0.4 mm thick. The elastically concave rectangular other flat-sided surface  102  of the hollow body  10  along the longitudinal axis A has a maximum depth of curvature t in the center  110  of approximately 100 μm relative to the front ends  105  of the hollow body  10 .  
         [0126]     Also vertical to the longitudinal axis A, in the direction of the width of the hollow body  10 , i.e. along the line III-III in  FIG. 1 , is a concave curvature of the other flat-sided surface  102  of the hollow body  10 , as shown in  FIG. 3   b.    
         [0127]     With the power semiconductor module  1 ′ shown in  FIG. 1 , the power semiconductor elements  20  and  20 ′ secured to the electrically-insulating layer  18  of the cooling device, are arranged in succession in plan view onto the surface  180  of this layer  18  next to the strut  60  along both long sides  62  of the strut  60  (see  FIG. 4 ) and are located above the coolant fluid  3  flowing in the hollow body  10  along these two long sides  62 .  
         [0128]     On each long side  62  of the strut  60  is, for example, a row each including six power semiconductor elements  20 ,  20 ′, that are arranged in succession in the direction of flow of the coolant fluid  3  (see  FIG. 4 ) flowing along the long sides  62 .  
         [0129]     Two first power semiconductor elements  20  in each row are, for example, IGBTs, two of the succeeding power semiconductor elements  20 ′ are, for example, diodes and two power semiconductor elements  20  following these diodes  20 ′ are again IGBTs.  
         [0130]     The diodes  20 ′ produce a greater amount of heat when operating than the IGBTs  20  and therefore for optimum cooling effect by the cooling device  1  the two diodes  20 ′ in each row are placed between the two pairs of IGBTs  20 .  
         [0131]     To connect into a known electrical circuit, the IGBTs  20  and diodes  20  are electrically connected in a known manner to busbars  21  arranged on the electrically-insulating layer  18 . For example, a single busbar  21  can be arranged above the strut  60 , or two or more busbars  21  stacked one above the other and electrically-insulated from each other can be arranged above the strut  60  and/or other busbars  21  can, for example, be arranged between the layer  18  and the power semiconductor elements  20 ,  20 ′ either individually or also stacked one above the other and electrically insulated from each other on the electrically-insulating layer  18 .  
         [0132]     The busbars  21  and other electrical conductors can be created by structuring one or more layers of electrically-conducting material on the electrically-insulating layer  18 .  
         [0133]     For the module  1 ′ shown in  FIG. 1 , the current collectors for the busbars  21  are designated as  22 .  
         [0134]      FIG. 7  shows how a cooling device  1  or module  1 ′ with a support  4  can be designed to form an arrangement  1 ″, including the cooling device  1  and the support  4 , or to form an arrangement  1 ″ including the module  1 ′ and the support  4 .  
         [0135]     The support  4 , shown only in part, is designed so that it has an even surface  41  in which, for each coolant fluid opening  11  in the concave other flat-sided surface  102  of the hollow body  10  of the cooling device  1  there is a termination  401  of a coolant fluid channel  40 , formed in the support  4 , assigned in each case to one of these coolant fluid openings  11 , for the supply or removal of coolant fluid  3  to and from the hollow body  10 .  
         [0136]     The even surface  41  of the support  4  and the concave other flat-sided surface  102  of the hollow body  10  of the cooling device  1 , are facing towards each other and arranged so that each coolant fluid opening  11  of the cooling device  1  is opposite the termination  401  of the support  4  assigned to this coolant fluid opening  11 .  
         [0137]     O-rings  7  of elastic material, each of which encloses a coolant fluid opening  11  of the cooling device  1  and the termination  401  of the fluid channel  40  of the support  4  opposite this coolant fluid opening  11 , are arranged between these surfaces  41  and  102  of the support  4  facing towards each other and the cooling device  1 .  
         [0138]     The cooling device  1  and the support  4  are fixed to each other by the fixing device  5  of the cooling device  1  in such a way that the concave other flat-sided surface  102  of the hollow body  10  of the cooling device  1  is pressed elastically flat in the direction of the arrow P (see  FIGS. 2 and 4 ) pointing to the even surface  41  of the support  4  and each O-ring  7  is compressed between this flat-pressed surface  102  and the even surface  41  of the support  4 , so that it seals the coolant fluid opening  11  of the cooling device  1  and the termination  401  of the coolant fluid channel  40  of the support  4  opposite this coolant fluid opening  11 , both of which are enclosed by the O-ring  7 , fluid-proof against the environment.  
         [0139]     Each O-ring  7  is, for example, positioned in a recess  410  in the even surface  41  of support  4  so that it does not slip sideways when assembling arrangement  1 ″ or  1 ′″. A recess of this kind could either alternatively or additionally also be formed in the other flat-sided surface  102  of the hollow body  10 .  
         [0140]     Using the fixing device  5  including the two threaded holes  12  in the hollow body  10  and the threaded pins  13 , assembly is carried out, for example, so that after arranging the cooling device  1  or module  1 ′ and the support  4  in such a way that the other flat-sided surface  102  of the hollow body  10  and the even surface  41  of the support  4  are facing towards each other and the O-rings  7  are arranged in the correct position between them, so that the threaded pins  13  are inserted through the through holes  134  formed in the support  4 , that lie opposite the openings  120  of the threaded holes  12  in the hollow body, and are then screwed into the threaded holes  12 , and that then on the side of a surface  42  of the support  4 , that is facing away from the even surface  41  of the support  4 , a nut  13 ′ is screwed onto each of the threaded pins  13  projecting through the support  4  and then tightened so that the other flat-sided surface  102  of the hollow body  10  is pressed flat, the O-rings are compressed and the hollow body  10  and support  4  are secured to each other. Washers can also be used that are to be placed on the threaded pins  13  between the support  4  and the nuts  13 ′.  
         [0141]     A through-hole  134  formed in the support  4  can also be a threaded hole with an internal thread through which the threaded pins  13  can be screwed to screw into a threaded hole  12  in the hollow body  10 .  
         [0142]      FIG. 7  actually shows an arrangement  1 ′″ including a module  1 ′ and support  4 . The arrangement  1 ″ including cooling device  1  and support  4  results if the illustrated electrical components  20 ,  20 ′ and  21  are ignored.  
         [0143]     The support  4  is preferably a part of an electrical transmission system  4 ′, particularly an electrical transmission system  4 ′ for a vehicle for cooling the power semiconductor elements required for the electrical supply of the part.  
         [0144]     The cooling device  1  and the module  1 ′ are characterized by their extremely flat construction, and particular suitability for installation in confined spaces.  
         [0145]     The invention has been described in detail with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention covered by the claims which may include the phrase “at least one of A, B and C” as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in  Superguide v. DIRECTV , 69 USPQ2d 1865 (Fed. Cir. 2004).