Abstract:
A device for cooling a vehicle battery is provided that includes a plurality of electric storage elements, and a cooling body being flowed through by a coolant fluid, wherein at least one of the electric storage elements is fixed at least on one cooling plate in thermal contact, and wherein the cooling plate is connected to the cooling body so that heat may be transferred from the storage element to the fluid, wherein the cooling plate has a planar mechanical connection to the cooling body.

Description:
[0001]    This nonprovisional application is a continuation of International Application No. PCT/EP2009/004292, which was filed on Jun. 15, 2009, and which claims priority to German Patent Application No. DE 10 2008 028 400.9, which was filed in Germany on Jun. 17, 2008, and which are both herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a device for cooling a vehicle battery. 
         [0004]    2. Description of the Background Art 
         [0005]    The cooling of electrical energy storage devices of modern motor vehicles poses special demands on account of the sometimes high power density. Such energy storage devices can be used as batteries for electric or hybrid vehicles, among other uses. These can be lithium-ion batteries, supercaps, fuel cells, conventional rechargeable batteries, or combinations of such elements. A number of proposals for efficient cooling of such components are known, although these are often laborious or costly to produce, or their performance is limited. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to provide a device for cooling a motor vehicle battery that can be manufactured easily and economically, and that provides effective and reliable cooling. 
         [0007]    A full-area mechanical connection provides good thermal contact, something which is only achievable with difficulty when the cooling plates are attached to the cooling element solely by adhesive means, for example. In an embodiment, the cooling element can be an essentially plate-like body through which fluid flows, wherein the fluid can be a liquid coolant of a cooling circuit, or also a refrigerant, e.g. of a vehicle air conditioning system, which evaporates in the cooling element. Also possible is a multiple flow design of the cooling element with a coolant flow and a refrigerant flow in order to be able to provide adequate cooling output in all operating situations. 
         [0008]    In an embodiment, the mechanical connection can be designed such that the cooling plate can be attached to the cooling element after connection to the electrical element. In this way, the production steps can be rationally separated and can be better automated. The connection of the electrical elements to the cooling plate in this design can take place by means of adhesives, clamping retention, or other means, for example. In particular, the electrical elements can be lithium-ion batteries in a flat design without an inherently rigid envelope (“coffee-bags”). 
         [0009]    To ensure adequate mechanical stiffness and thermal conductivity, the cooling plate can have a thickness between approximately 0.2 mm and approximately 2 mm. Depending on requirements, the cooling plate may comprise a plurality of sheet-metal layers, which makes it possible to achieve good flexibility with an overall cross-section that is still adequate. It is generally preferred for the cooling plates to be made of a material that has good thermal conductivity while also being formable, such as aluminum, copper, or copper-coated aluminum, for instance. 
         [0010]    In an embodiment of the invention, the cooling element can have an opening, wherein the cooling plate extends at least partway through the opening. It is especially preferred in this design for provision to be made for a part of the cooling plate that projects beyond the side of the cooling element opposite the electrical element to be deformed for mechanical connection, in particular force-locking and/or frictional and/or interlocking connection, with the cooling element. The attachment by means of deformation of the cooling plate makes it possible to achieve good thermal contact along with permanent, reliable attachment to the cooling element. 
         [0011]    In a variation of the exemplary embodiment, the mechanical joining is accomplished with a sheet-metal part arranged on the cooling element, in particular by forming the cooling plate and the sheet-metal part together. In this variation, the sheet-metal part (or the multiple sheet-metal parts) can be attached by means of, e.g., full-area soldering, in particular during the course of manufacturing the cooling element, by which means the sheet-metal part and the cooling element are connected reliably and in especially good thermal contact. 
         [0012]    In the interests of good heat removal, it is preferred for the projecting part of the cooling plate to be formed directly onto the cooling element. 
         [0013]    In an embodiment, the opening of the cooling element can have the form of a slot with an enlarged central region. The central region can have a round cross-section with, in particular, conical edges, for example, so that forming of the cooling plate onto this region of the opening produces a sort of half-shell hollow rivet whose mechanical strength and thermal connection are especially great. 
         [0014]    In another exemplary embodiment, the cooling plate has, at its end facing the cooling element, a formation tapering in a shallow angle, wherein the formation engages in a corresponding recess of the cooling element, in particular frictionally. In a preferred detailed design, an included angle of the formation on the cooling plate is between approximately 3° and approximately 9°, in particular between approximately 5° and approximately 7°. Retention in the case of such an attachment is largely frictional, wherein the selected included angle lies in the range of the self-limiting angle of friction of the material pairing. In addition to a large contact area, this design also offers the advantage that the recess does not have to extend completely through the cooling element or be formed as an opening. 
         [0015]    In another exemplary embodiment of the invention, the cooling plate can be connected to the cooling element by at least one rivet. Riveting also presents itself as especially suitable for achieving full-area contact, between the cooling plate and cooling element that is subjected to force. In a first detailed design, the rivet is made of plastic, being economical and easily workable. In particular, a plurality of the rivets can be formed as a single piece with a plastic rail, which makes it possible to further simplify and automate assembly. Forming (deformation) of the plastic rivet heads can be accomplished by heat staking, ultrasonic welding, or other thermomechanical forming methods. In a supplementary or alternative modification, the rivet is made of metal and is designed as a blind rivet in particular. Especially high contact force of the cooling plate and cooling element, and hence especially good thermal contact, can be achieved with metal rivets. 
         [0016]    In another embodiment of the invention, a groove is provided in the cooling element and a formation corresponding to the groove is provided on the cooling plate, wherein the cooling plate can be inserted in a force-locking manner in the groove by means of the formation. This measure makes it possible to achieve a force fit in at least two spatial directions, with large contact areas inside the groove additionally being possible. Depending on requirements, additional attachment through adhesive bonding or through resilient clamping may be present, in particular to secure against displacement in the direction of the groove. 
         [0017]    In another embodiment of the invention, provision is made for the cooling plate to be held against the cooling element under pressure by a clamping element, which achieves good thermal contact in a simple manner. In a preferred refinement, the clamping element in this design is supported on a housing cage connected to the cooling element, wherein in particular multiple cooling plates are located in the housing cage. Assembly can be further simplified and automated by this means. 
         [0018]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
           [0020]      FIG. 1  shows a detail view of a first exemplary embodiment of the invention with a cooling plate that extends through the cooling element. 
           [0021]      FIG. 2  shows a plan view from below of a second exemplary embodiment of the invention before and after a partial forming of the cooling plate. 
           [0022]      FIG. 3  shows the device from  FIG. 2  in two sectional planes along the lines A-A and B-B. 
           [0023]      FIG. 4  shows another plan view from below of the device from  FIG. 2  after complete forming of the cooling plate. 
           [0024]      FIG. 5  shows another exemplary embodiment of the invention with riveting of the cooling plate and cooling element. 
           [0025]      FIG. 6  shows a modification of the exemplary embodiment from  FIG. 5 . 
           [0026]      FIG. 7  shows another modification of the exemplary embodiment from  FIG. 5 . 
           [0027]      FIG. 8  shows another exemplary embodiment of the invention using interlocking grooves. 
           [0028]      FIG. 9  shows a cooling plate of another exemplary embodiment with conical formations. 
           [0029]      FIG. 10  shows a schematic cross-sectional view through the cooling plate from  FIG. 9  attached to a cooling element. 
           [0030]      FIG. 11  shows a cross-sectional view of a cooling plate from another exemplary embodiment of the invention. 
           [0031]      FIG. 12  shows the exemplary embodiment from  FIG. 11  with cooling plate attached to the cooling element by means of a clamping element. 
           [0032]      FIG. 13  shows a three-dimensional view of the exemplary embodiment from  FIG. 12  in a partially assembled state without the clamping element. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    In the first exemplary embodiment shown in  FIG. 1 , a cooling element  1  that fluid flows through has a plurality of slot-like openings  2 , with one cooling plate  3  inserted through each opening. Attached to the cooling plate  3  by means of adhesive are one or more lithium-ion batteries in the “coffee bag” design (not shown). The part extending through the opening  2  projects on the other side (the top in the drawing) of the cooling element, where it is joined to a sheet-metal part  4  by flanging or folding  5 . The sheet-metal part  4  has a full-area, bent-back projection  4   a , by means of which it is full-area soldered to the cooling element. 
         [0034]    Due to the fact that the cooling plate  3  and sheet-metal part  4  are formed together, a force-locking, frictional, and interlocking connection is created that has good thermal conductivity. If necessary, additional sections of the cooling plate  3  may be bent back in the manner of feet and rest over their full area against the underside of the cooling element in  FIG. 1 . 
         [0035]      FIG. 2  shows another possibility for the attachment by forming of a cooling plate that has been inserted through an opening  2  in the cooling element  1 . 
         [0036]    To this end, the opening has lateral slot-like sections  2   a  and a central, essentially circular section  2   b  with a greater width. The end region of the cooling plate that is inserted through the cooling element is divided into three segments  3   a ,  3   b ,  3   c , wherein the lateral segments  3   a ,  3   b ,  3   c  are folded back by approximately 90 degrees and are not inserted through the slot-like sections  2   a  of the opening  2 , but instead support the cooling plate on the cooling element over their full area. The central segment  3   b  that is inserted through the opening  2  is formed onto the central region of the opening  2   b  in the manner of a half-shell hollow rivet. Overhangs of the segment extending through the slot-like section  2   a  are folded back. 
         [0037]    For purposes of illustration, different sectional planes are shown on the left side and on the right side in the cross-sectional view in  FIG. 3 . Also visible are end regions of the lithium-ion cells  6  glued onto the cooling plate  3 . 
         [0038]    For purposes of illustration, the plan view from below in  FIG. 4  also shows the segments  3   a ,  3   c  that are supported on the opposite side of the plate-like cooling element, and that would not actually be visible. The segments  3   a ,  3   c  are also provided with beading  3   d  for reinforcement. In the exemplary embodiment shown, two cooling plates are introduced into each opening  2 , wherein this may also be two sheet-metal layers of the same cooling plate, depending on requirements. In the case of a cooling plate made of multiple layers, the layers can be joined together at their other end in a manner similar to the connecting region  5  in  FIG. 1 . 
         [0039]    In the embodiment in  FIG. 5 , a plastic rail  7  is attached to the cooling plate (not shown), for example by means of clips, adhesives, or injection-molding. The plastic rail  7  has multiple projecting pins or rivets  8 , which are inserted through openings  9  in the cooling element  1  and are then formed into rivet heads. The forming can take place by means of hot staking or other suitable means. 
         [0040]    The cooling element  1  has flat tubes  1   a  in which refrigerant or a coolant flows. For further reinforcement, the rivets are carried in reinforcing elements  9 . 
         [0041]      FIG. 6  shows a modification of the embodiment from  FIG. 5  in which no reinforcing elements are provided. 
         [0042]      FIG. 7  shows another variation of the riveting of cooling plate  3  and cooling element  1  in which a metallic blind rivet is inserted through openings in cooling element  1  from the side facing away from the electrical elements, and a tab of the cooling plate  3  resting on the cooling element  1  is inserted and then formed. This method of attachment is especially advantageous for space-limited construction, such as exists in the present example as a result of the electrical elements  6  extending over the rivet  10 . 
         [0043]      FIG. 8  schematically shows an exemplary embodiment in which a formation  11  at the end of the cooling plate  3  is inserted in an interlocking way in a corresponding groove  12  of the cooling element  1 . If a friction or spring tension achieved through shaping does not provide adequate attachment in the direction of insertion, adhesive bonding or else folding back of sheet-metal parts projecting at the ends can take place in addition. 
         [0044]      FIG. 9  and  FIG. 10  show an exemplary embodiment in which formations are provided at the ends of the cooling plate  3  that taper in a shallow angle of approximately 6° in the manner of tongues  13 , which are inserted in corresponding conical recesses  14  of the cooling element  1 . The recesses  14  may be present in the form of blind holes or else as openings (see  FIG. 10 ) that pass all the way through. Permanent frictional attachment with good full-area contact can be achieved through an appropriate choice of the cone angle. Additional retention can be achieved by the subsequent application of adhesive, or else by additional locking through suitable shaping of the tongues  13 . 
         [0045]      FIG. 11  through  FIG. 13  show another exemplary embodiment of the invention in which the ends of the cooling plate  3  are bent into the form of flat feet  15 , which rest on the surface of the cooling element  1 . At the opposite end, the cooling plates  3  are held and pressed against the cooling element  1  by a clamping element  16  in the manner of a straight clip that continuously overlaps the cooling plate, or a pressure plate  16   a  with resiliently elastic connecting elements  16   b  that are engaged at the sides. 
         [0046]    The connecting elements  16   b  are connected at one side to the clips  16   a  and at the other side are hooked in recesses  17   a  of a housing cage  17  in a preloaded manner. The housing cage  17  encloses a plurality of the cooling plates  3  and is permanently attached to the cooling element  1 , which can be accomplished by soldering, for example, during the course of manufacturing the cooling element  1 . 
         [0047]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.