Abstract:
The invention relates to a battery ( 10 ) for a vehicle. Said battery comprises a plurality of battery cells ( 12 ), which are arranged in a housing ( 16, 18, 20 ) of the battery ( 10 ), and also a cooling device ( 22, 24 ) for dissipating heat from the battery cells ( 12 ). A material ( 32 ), which takes up a first volume in a basic state and takes up a volume which is greater than the first volume in an expanded state, is introduced between the housing ( 20 ) and the cooling device ( 22, 24 ). The cooling device ( 22, 24 ) is pressed against the battery cells ( 12 ) by the material ( 32 ) which has changed over to its expanded state. The invention also relates to a method for producing a battery ( 10 ) of this kind.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2012/002130, filed May 18, 2012, which designated the United States and has been published as International Publication No. WO 2012/163484 and which claims the priority of German Patent Application, Serial No. 10 2011 102 765.7, filed May 28, 2011, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention relates to a battery for a vehicle, with a plurality of battery cells being arranged in a housing. The battery includes a cooling device for removing heat from the battery cells. Furthermore, the invention relates to a method for producing such a battery. 
     DE 10 2007 021 293 A1 describes a battery for an electric vehicle, fuel cell vehicle or hybrid vehicle, Individual battery cells which are combined to form a cell stack are surrounded on the outside by a common housing of plastic. The housing includes a container which is open on one side and a lid which closes the container, with both being manufactured by injection molding. To ensure that the battery cells are fixed in place and secured without play in the housing, positioning protrusions are provided on the bottom and the lid of the housing and have zones of different elasticity. The softer zone of a respective positioning protrusion enables a compensation of manufacturing tolerances of the battery cells. The batteries are cooled by pipes in the housing which are supplied with cooling fluid. Mounted to the pipes are numerous thin sheets which are used to remove heat from the battery cells. The sheets are shaped to suit the respective battery cell, with a respective battery cell being accommodated in a receiving space which is formed by one or more sheets. 
     DE 10 2009 004 543 A1 describes a vehicle battery with round cells arranged between two cooler walls. Cooling channels for a coolant are provided in the cooler walls. Profile elements of heat-conducting material are provided between the battery cells so as to enable a heat transfer between the round cells via the profile elements. Tensioning devices tension together the two cooler walls so as to press them with comparably great force against the profile parts and the round cells. 
     EP 2 065 963 A2 describes a battery for a vehicle, with a plurality of battery cells forming a battery block. A cooling plate is in thermal contact with a bottom of the battery block. The cooling plate has a hollow space within which cooling pipes are arranged. The cuboid cooling plate with the hollow space includes an upper wall which is in contact with the bottom of the battery block. The expansion of a plastic foam filled in the hollow space causes an intimate contact of the cooling pipes with the upper wall of the cooling plate. 
     Establishing a good heat-conducting contact of the cooling device with the battery cells is fairly complicated in these batteries that are known in the art. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide both a battery of the afore-mentioned type and a method for manufacturing such a battery that are capable to realize a good heat removal during cooling operation in a particularly simple manner. 
     According to one aspect of the invention, this object is achieved by a battery for a vehicle, including a plurality of battery cells arranged in a housing, and a cooling device for removing heat from the battery cells, wherein a material is introduced in a gap provided between the housing and the cooling device and occupies in a basic state a first volume and in an expanded state a volume which is greater than the first volume, with the cooling device being pressed against the battery cells as the material changes to its expanded state. 
     According to another aspect of the invention, this object is achieved by a method for producing a battery for a vehicle, wherein a plurality of battery cells is arranged in a housing of the battery, and a cooling device is arranged in the housing and configured to remove heat from the battery cells, wherein a material is introduced into a gap between the housing and the cooling device, with the material undergoing an increase in volume to thereby press the cooling device against the battery cells. 
     Advantageous configurations with suitable refinements of the invention are set forth in the dependent patent claims. 
     The battery according to the invention includes a material which is introduced between the housing and the cooling device and which occupies in a basic state a first volume and in an expanded state a volume which is greater than the first volume. As the material changes to its expanded state, the cooling device is pressed against the battery cells. Such a material, also called expansion agent, is capable to realize a particularly good contact of the cooling device upon the battery cells. This, in turn, results during operation of the cooling device in a particularly good dissipation of heat released by the battery cells. 
     The introduction of the expansion agent in a gap between the housing and the cooling device is also especially easy to implement so that the battery can be manufactured in an especially simple manner. The increase in volume of the expansion agent after introduction between the housing and the cooling device results in a great contact pressure to urge the cooling device in contact with the battery cells. 
     According to an advantageous configuration of the invention, the material involves a rigid foam material when assuming its expanded and hardened state. Such a foam material, such as in the form of an assembly foam, can be introduced between the housing and the cooling device in an especially simple manner. The assembly foam involves for example a single-component assembly foam or a two-component assembly foam which can be made available cost-effectively and is easy to handle. 
     The cooling device includes, preferably, at least one profile part through which a coolant can flow. Such a profile part can be made in an especially simple and cost-effective manner by extrusion and the coolant provides a particularly efficient heat removal during operation of the cooling device. 
     It has been shown as advantageous when a heat-conducting paste is arranged between the at least one profile part and a sheathing of the respective battery cell. As a result, manufacturing tolerances of the battery cells and/or the cooling device and/or the housing can be compensated in a particularly good way. The heat-conducting paste provides in addition a wide-area contact of the cooling device upon the battery cells and prevents the presence of thermally insulating air between the sheathing of the battery cells and the cooling device. 
     In addition, or as an alternative, a heat-conducting adhesive may be arranged between the profile part and the sheathings of the battery cells. This ensures during the cooling operation an especially good heat transfer from the battery cells onto the cooling device not only but also a particularly reliable hold of the profile parts on the sheathings of the battery cells. 
     According to a further advantageous configuration, the at least one profile part is made from an aluminum alloy. This material provides an especially good heat transfer from the battery cells onto the coolant. Moreover, a profile part of an aluminum alloy has, advantageously, little weight. 
     The profile part may also be made from a non-destructive flexible plastic. The battery may also include at least one profile part of an aluminum alloy and at least one profile part of plastic. When the battery includes a profile part of non-destructive, deformable, especially elastic plastic, the risk of damage to the profile part is especially slight when the battery exposed to a force in the event of an accident. Thus, when exposed to a force, the battery cells may be displaced in relation to the cooling device, without experiencing a buckling or breaking of the profile part. As a result, coolant is effectively prevented from escaping the cooling device. 
     In addition, when using plastic for the profile part a more even heat removal across the entire battery is realized because of a heat transfer coefficient that is lower than of metal. A profile part with great heat transfer coefficient causes comparably intense heating of the coolant by the battery cells arranged upstream so that a less efficient heat dissipation is established for the battery cells arranged downstream in view of the smaller temperature differential. 
     It has been shown as further advantageous, when at least one wall of the housing of the battery is formed by separators which insulate the battery cells electrically from one another. As they are provided anyway for electrical isolation, the separators, can be used to form the housing so that the battery is especially easy to manufacture. The separators can hereby be especially connected in such a way that the at least one wall of the housing is hermetically sealed against water and/or moisture, especially air humidity. This may be ensured by bonding the separators with one another. 
     Finally, it has been shown as advantageous, when the at least one wall forms at least one receiving space for the cooling device. The cooling device can then simply be placed during manufacture of the battery in the receiving space which is established as a result of the installation of the separators. Subsequently, the expansion agent placed in the receiving space then provides the respectively great contact pressure by which the cooling device is pressed against the battery cells. 
     In the method according to the invention for producing a battery for a vehicle, a plurality of battery cells is arranged in a housing of the battery. In addition, a cooling device is arranged in the housing and configured to remove heat from the battery cells. Subsequently, a material is introduced into the gap between the housing and the cooling device, and the cooling device is pressed against the battery cells as the material undergoes an increase in volume. A cooling device in contact with the battery cells is this way results in an especially efficient removal of heat from the battery cells during cooling operation. 
     The advantages described for the battery according to the invention and preferred embodiments apply also for the method according to the invention for producing a battery. 
     Both the features and combinations of features mentioned above in the description and the features and combinations of features mentioned hereinafter in the figure description and/or shown in the figures alone can be used not only in the respectively indicted combination but also in other combinations or when taken alone, without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Further advantages, features and details of the invention are set forth in the claims, the following description of preferred embodiments and with reference to the drawings. It is hereby shown in: 
         FIG. 1  a perspective view of a battery for storing and supplying drive energy for a vehicle; 
         FIG. 2  a perspective view of a separator which electrically insulated two battery cells from one another; 
         FIG. 3  a sectional view through the battery according to  FIG. 1 ; 
         FIG. 4  a bottom view of a lid of the battery to close off the top of a housing, formed by the separators, for the battery cells; 
         FIG. 5  a top view of the lid according to  FIG. 4 ; and 
         FIG. 6  a further sectional view of a portion of the battery according to  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A battery  10 , shown in  FIG. 1  for a vehicle, is formed as a lithium-ion battery for example. The battery  10  includes a plurality of battery cells  12  which are electrically insulated from one another by separators  14  which are made of plastic and also referred to as spacers (cf.  FIG. 6 ). The prismatic battery cells  12  form here a stack. 
     The separators  14 , which are connected with one another by bonding, form side walls  16  and a bottom plate  18  (cf.  FIG. 2 ) of a housing of the battery  10  in which the stack of battery cells  12  is accommodated. In the area of the bottom plate  18  of the housing, as formed by the separators  14 , two passages  20  (cf.  FIG. 2 ) are formed by the separators  14  for receiving two profile parts  22 ,  24  of a cooling device (cf.  FIG. 1 ). 
     The profile parts  22 ,  24  are configured as flat tubes through which a coolant flows and in which ribs  26  form a plurality of cooling channels in parallel relationship (cf.  FIG. 3 ). Arranged at a first of the profile parts  22  is a coolant port  28  for supply of the coolant to the profile part  22 . A coolant port  30  provided on the second profile part  24  is provided to carry away the heated coolant from the battery  10  to a (not shown) cooler. 
       FIG. 3  in particular shows that the profile parts  22 ,  24  have a height which is slightly less than a height of the passages  20  receiving the profile parts  22 ,  24 . An assembly foam  32  is arranged in the region of the passages  20  in a gap between the bottom plate  18 , formed by the separators  14 , and the profile parts  22 ,  24 . 
     The assembly foam  32  is introduced during manufacture of the battery  10  in the passages  20  after the profile parts  22 ,  24  have been placed in the passages  20 . The increase in volume of the assembly foam  32  as a result of the expansion of the assembly foam  32  causes the profile parts  22 ,  24  to be pressed against the sheathings of the battery cells  12  at a great pressing force. The expanded hardened assembly foam.  32  ensures that the great pressing force is maintained continuously. 
     In addition, a layer of heat conducting paste  34  is provided between the profile parts  22 ,  24  and the battery cells  12  to compensate tolerances and to ensure an especially good wide-area heat transfer between the profile parts  22 ,  24 . 
     The profile parts  22 ,  24  may be made from an aluminum alloy. As an alternative, the profile parts  22 ,  24  may be made from a flexible, non-destructively bendable plastic so that the profile parts  22 ,  24  do not buckle or break when the battery  10  is exposed to a force in the event of an accident, and any escape of coolant out of the profile parts  22 ,  24  is prevented. 
     When using plastic for the profile parts  22 ,  24 , an especially even heat removal from the battery cells  12  is moreover established because as a result of the comparably low heat transfer coefficient of plastic, there is no large heat input into the coolant by battery cells  12  which are arranged upstream—as viewed in flow direction of the coolant through the coolant port  28 . 
     The housing for the stack of battery cells  12  is formed by the separators  14 , respectively arranged between two battery cells  12 , and two separators  36  at the end faces to close the stack of battery cells  12  (cf.  FIG. 1 ). The separators  24 ,  36  made from inherently rigid plastic are bonded to one another at the respective contact areas  38  (cf.  FIG. 6 ). 
     In addition, form-fitting elements, for example pins  40  shown in  FIG. 3 , are provided in the contact areas  38  and realize with complementary indentations in the separators  14 ,  36  for a correct positional arrangement of the separators  14 ,  36  upon one another. The separators  14 ,  36  bonded to one another form a housing which hermetically seals the stack of the battery cells  12  on five sides, and a lid  42  (cf.  FIG. 4 ) tightly closes the housing at the top against water and moisture. 
     The integrity of the housing is ensured by side panels  44  and end panels  46  (cf.  FIG. 1 ) which surround the outer circumference of the housing. The end panels  46 , made in particular of spring steel, have hereby formed thereon tongues  49  for engagement in respective tabs provided in the side panels  44 . A further alignment plate  48  extends at the bottom between the two profile parts  22 ,  24  from the front end panel  46  in  FIG. 1  to the rear end panel and is also secured to the end panels  46 . 
     The joined separators  14  form guide rails  50  for locking lugs  52  (cf.  FIG. 3 ) provided on the lid  42 . The locking lugs  52  are bonded in the guide rails  50  with elastic and sealing adhesive (cf.  FIG. 4 ). In this way, the housing is also tight at the top for the stack of battery cells  12 . 
     Formed in one piece with the separators  14  are domes  54  or bushes which extend through respective through openings in the side panels  44  and fixing plate  48  (cf.  FIG. 3 ). In this way, the side panels  44  and the alignment plate  48  maintain predetermined distances between the separators  14  (cf.  FIG. 1 ). The domes  54  are swaged hot after being placed in the through openings to ensure a reliable hold of the side panels  44  and the alignment plate  48 . 
     Integrated in the lid  42  are busbars  56  via which poles of the battery cells  12  are contacted. For this purpose, the busbars  56  can be connected with the poles of the battery cells  12  by screws  58  (cf.  FIG. 3 ). As an alternative, it is possible to fuse the busbars  56  with the poles of the battery cells  12 . A cover  60  which is sealed by a seal  62  against a base body of the lid  42  ensures that the screws  58  and the busbars  52  are protected at the top against penetration of moisture or water. 
     Further integrated in the lid  42  are lines  64  via which the voltage of the battery cells  12  is ascertained. Furthermore, a channel  66  is provided in the lid  42  for discharging hot gases escaping from the battery cells  12  in the event of a malfunction. Electric energy can be drawn from the battery  10  for a drive engine or introduced into the battery  10  via two high-voltage terminals  68  integrated in the lid  42 . 
     A sealing casting compound  76  may be provided in a region of the lid  42  in which one end of the high-voltage terminal  68  is arranged and formed as contact finger (cf.  FIG. 6 ). A circuit board  70  (cf.  FIG. 5 ) provided in the lid  42  is covered in the battery  10  at the top also by a cover  72  (cf.  FIG. 1 ). 
     As is shown in  FIG. 6 , the coolant port  30  is snugly fitted to the profile part  24 , associated to this coolant port  30 , via a sealing ring  74  which is arranged in the terminal separator  36 . The attachment of the second coolant port  28  to the profile part  22 , associated thereto, is realized in an analogous manner.