Abstract:
A protective housing ( 1 ) for a galvanic cell in a motor vehicle four side walls ( 2   a,    2   b,    3   a ) that form a lateral enclosure for a receptacle space for the galvanic cell. A base and a cover ( 4 ) extend across the lateral enclosure of the receptacle space. A cover cross member ( 8 ) is attached to the cover ( 4 ) and projects out beyond two opposed side walls ( 2   a,    2   b ) for connection to a shell of the motor vehicle so that the protective housing ( 1 ) is suspended in a rotationally fixed fashion in the motor vehicle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a protective housing for a galvanic cell in a motor vehicle. In this context, protective housing means a structure that can reliably absorb or pass on forces that occur in a crash without relatively severe damage to the protective housing or the galvanic cell therein. The galvanic cell preferably is a high voltage battery, such as a lithium ion or a nickel metal hydride battery. 
     2. Description of the Related Art 
     U.S. Pat. No. 5,501,289 discloses a relatively complex floor structure for an electric vehicle that is used for accommodating batteries. 
     DE 11 2005 000 492 discloses a storage battery arrangement with a mounting structure that can be attached to a longitudinal member and cross member of a vehicle. However, a mounting structure mounted in this way can become twisted in a crash and, as a result, can damage adjacent elements, such as a fuel tank, that do not lie in the load path. 
     DE 10 2007 023 391 discloses a protective housing for a vehicle battery having two transverse walls and two longitudinal walls that together form a lateral enclosure. At least two base cross members and at least two cover cross members are provided on the enclosure for attachment in the motor vehicle. DE 10 2007 023 10 2007 023 391 was not published before the priority date claimed herein. 
     The object of the invention is to provide a protective housing for a galvanic cell, in particular a high voltage battery, in a motor vehicle. It is another object of the invention to provide such a protective housing that is of simple design, that can be used universally and that is relatively secure in the event of a crash. 
     SUMMARY OF THE INVENTION 
     The invention relates to a protective housing for a galvanic cell in a motor vehicle. The protective housing has four side walls that together form a lateral enclosure for a receptacle space for the galvanic cell. The protective housing also has a base and a cover that bound opposite bottom and top regions of the receptacle space. A cover cross member is attached to the cover and projects out beyond two of the opposite side walls. The cover cross member enables the protective housing to be connected to a shell of the motor vehicle in a rotationally fixed fashion and to achieve a suspended mounting the receptacle space. The base and the cover reinforce the protective housing and enclose the receptacle space to produce an enclosed protective housing. The receptacle space defines a stable cage that deforms only to a relatively small degree even in the event of a crash, thereby avoiding damage to the galvanic element accommodated therein. The configuration of the lateral enclosure, the cover and the base provides a flexurally stable and flexurally rigid protective housing and causes a load that causes a load that occurs in a crash to be taken up and/or passed on in an optimum way. 
     This crash-proof configuration results in an inherently stable structure and permits the use of the separate cover cross member for attaching the receptacle space in a suspended fashion. More particularly, the cover cross member projects out laterally beyond the receptacle space so that the protective housing can be mounted in a suspended fashion in the shell of the vehicle. The weight of the protective housing is supported essentially by the cover cross member, and the connection between the cover cross member and the shell of the vehicle is merely for the purpose of attachment. As a result the connection between the cover cross member and the shell of the vehicle can be of relatively simple design and can be achieved, for example, by clamps, screws, bolts or other suitable attachment means. As a result, further support, for example on the lateral enclosure or the base of the receptacle space can be dispensed with. Nevertheless, a high degree of safety with respect to crashes is achieved because the protective housing is suspended in equilibrium after oscillation has stopped, and therefore is mounted in a rotationally fixed fashion. 
     The protective housing and the accommodated galvanic cell can be dismounted easily merely by releasing the corresponding connections, such as the electric connections and if appropriate the mechanical connection of the cover cross member that secures the protective housing to the shell of the vehicle. The protective housing then can be removed from the motor vehicle and serviced or replaced. 
     The protective housing is universally applicable to a plurality of different installation spaces can by employing a correspondingly configured cover cross member, which constitutes a structurally simple modification of the protective housing. More particularly, the protective housing does not need additional screwing points or other necessary connecting points to the shell of the motor vehicle. Instead the protective housing merely is mounted in the motor vehicle in a suspended fashion by the appropriately configured cover cross member. 
     The protective housing enables new installation spaces to be available by virtue of the suspended mounting. These additional installation spaces include those that do not have lateral attachment possibilities for a corresponding protective housing. 
     The side walls, the base and the cover may be substantially planar and may be fabricated from metal to provide flexural stability or flexural rigidity of the protective housing in all directions. As a result, the load that occurs in the event of a crash is accommodated or passed on particularly well. 
     The side walls may comprise extruded sections. The extruded sections exhibit sufficient rigidity and safety in crashes and have a relatively low weight. The extruded sections also enable a large number of structural possibilities. For example, the extruded sections can form chambers that can be made more rigid by inserting reinforcing sections that are made, for example, of steel. 
     The side walls preferably are separate components that are assembled, for example, by welding to form an enclosure. Thus, the protective housing is particularly easy to manufacture. 
     The protective housing achieves a stable position and high degree of protection against twisting. In particular, the cover cross member extends in a surface-covering fashion over more than half of the cover. The cover cross member projects out over two opposite side walls. Therefore, more than half of the area of the cover is covered in the direction orthogonal to the opposite side walls from which from which the cover cross member projects. In this context, the cover cross member can be screwed to the cover. This simple and effective way of connecting the cover cross member is made possible due to the stable structure of the protective housing. 
     The cover cross member preferably comprises two spaced apart sectional elements that are connected to one another by a further sectional element. The two spaced apart sectional elements may have a hollow part or recess defined, for example, by an L-shaped cross section. The further sectional element then is inserted into the hollow part or recess and welded in position. This design is warp-resistant and relatively lightweight. 
     The cover cross member preferably is screwed to the shell of the motor vehicle to secure the protective housing reliably. For this purpose, lateral end regions of the cover cross member have openings for screwing in the shell. As a result, the protective housing can be dismounted easily. Furthermore, the corresponding screws, the electrical connections of the galvanic cell and, if appropriate, further connections can be released easily so that the protective housing simply can be pulled out of the motor vehicle. Accordingly, a new protective housing can be mounted together with the galvanic cell in a suspended fashion during servicing of the motor vehicle. Of course, it is possible to provide clamps or other attachment means. 
     The side walls, the base, the cover and/or the cover cross member preferably are fabricated from aluminum to provide a particularly lightweight protective housing. 
     The protective housing together with the galvanic cell may be retrofitted to form a complete power supply module for a motor vehicle. For this purpose, elements for air-conditioning, in particular for cooling, the galvanic cell preferably are provided on at least one side wall of the protective housing. This assembly defines a power supply module that can be installed merely by making the necessary electrical connections and connecting corresponding feed lines and discharge lines for the air conditioning medium. 
     The protective housing may include means for air cooling the galvanic cell. The air cooling means may include a discharged air collector with a collecting element for carrying away the discharged air. It is therefore possible to form an electrical vehicle or hybrid vehicle in a simple way in terms of production technology. Specifically, the protective housing simply needs to be mounted in a suspended fashion and secured. The galvanic cell then is connected electrically and the protective casing is connected to lines for feed air and discharged air. 
     A control unit for electrically monitoring and controlling the galvanic cell preferably is provided in the region of the cover and the cover cross member preferably has a breakthrough in this region. The control unit enhances the module character of the protective housing and the galvanic cell. The control unit preferably can be accessed through the breakthrough in the cover cross member for servicing. The breakthrough and/or the position of the breakthrough are selected so that the stability of the cover cross member is not affected adversely. 
     The motor vehicle preferably has two spaced apart longitudinal members and the protective housing is mounted in a suspended fashion between the longitudinal members so that end regions of the cover cross member bear respectively on the longitudinal members. The longitudinal members constitute particularly stable support points. Here, it is possible to adapt to conditions of the motor vehicle, i.e. the installation space, irrespective of the size of the galvanic cell merely by correspondingly dimensioning the length of the cover cross member. It is then possible to screw the end regions of the cover cross member to the supporting regions of the respective longitudinal members to form a secure connection. 
     The motor vehicle may be a hybrid vehicle. Additionally, a conventional motor vehicle can be provided with a significant component for hybridization by simply mounting the protective housing of the invention in a suspended fashion in a suitable installation space. The rear region of the motor vehicle is the preferred installation space. Thus, the upper edge of the cover cross member bears approximately in the region of the lower edge of the floor pan. As a result, new installation space underneath the floor pan is made available for the galvanic cell, but none of the volume of the trunk is lost. If necessary, a spare wheel for the motor vehicle can be dispensed with. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a protective housing according to the invention. 
         FIG. 2  is a cross sectional view of the cover cross member of the protective housing. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A protective housing for a galvanic cell GC of a motor vehicle MV is identified generally by the numeral  1  in  FIG. 1 . The protective housing  1  has two substantially planar longitudinal walls  2   a ,  2   b  that extend in the longitudinal direction of the motor vehicle MV. In addition, the protective housing  1  has a rear transverse wall  3   a  and a front transverse wall  3   b , as shown in  FIG. 2 . The transverse walls  3   a ,  3   b  extend transverse to the longitudinal direction of the motor vehicle. The protective housing  1  also has a cover  4  and a base  5  opposed to the cover  4 . The side walls  2   a ,  2   b ,  3   a ,  3   b , the cover  4  and the base  5  are elements of an enclosed receptacle space for accommodating the galvanic cell. These elements are fabricated as individual parts in the form of aluminum extruded sections and then sections and then are combined to form the receptacle space. Depending on requirements, these elements may form chambers C in at least certain areas. The chambers C may be reinforced as required with inserted steel sections S. The individual elements are welded to one another or are attached in another suitable way. 
     The protective housing  1  also includes a cover cross member  8  that is attached to the cover  4 . The cover cross member  8  has a sectional element  10  that connects two sectional elements  11   a ,  11   b . The sectional elements  11   a ,  11   b  are L-shaped chamber sections in the illustrated embodiment. The sectional element  10  is a hollow chamber plate that is inserted in the two L-shaped sectional elements  11   a ,  11   b . The sectional elements  10 ,  11   a ,  11   b  preferably are manufactured from aluminum. Openings  14  are provided through the cover cross member  8  and can receive screws for attaching the cover cross member  8  on the cover  4 . The openings  14  are located on the lateral sides of the cover cross member  8  and hence are aligned transverse to the longitudinal direction of the motor vehicle MV since the lateral sides of the cover cross member  8  are transverse to the longitudinal direction of the motor vehicle MV. This structure is more resistant to twisting in the event of a crash, as compared to a cover cross member that extends in the longitudinal direction of a motor vehicle. The cover cross member  8  is screwed to the cover  4  using screws or bolts in the openings  14 . Of course, the cross member also can be formed in one piece and/or attached to the cover  4  in some other way, for example by welding. 
     The protective housing  1  can be retrofitted to form a complete power supply module for a hybrid vehicle. For this purpose, the protective housing  1  has an air conditioning module for the accommodated galvanic cell GC. The air conditioning module has a discharged air collector  20  with a discharged air connection  21 . A battery manager  25  also is provided as a control unit for controlling and monitoring the galvanic cell GC. An opening  26  extends through the cross members  8  so that the battery manager  25  is accessible for servicing. 
     The protective housing  1  is embodied as a module for supplying electrical energy. The module merely has to be mounted in a suspended fashion in a motor vehicle MV. Accordingly, a corresponding installation space is provided between two longitudinal members LM in the shell of the motor vehicle MV for accommodating the protective housing  1 . To secure the protective housing  1  firmly in the shell of the motor vehicle, the cover cross member  8  has openings  24  in its two end regions—viewed in the transverse direction—for forming a screwed connection of the protective housing  1  to the longitudinal members LM in the shell of the motor vehicle. As a result of the correspondingly wide configuration of the cover cross member  8 , the protective housing  1  is arranged in the motor vehicle MV in a way that is secured against twisting. Electrical contact then is made with the battery manager  25  and the feed lines and discharged air lines are connected via the corresponding connections, such as the discharged air connection  21 . This easily permits an essential component of a hybrid vehicle to be installed in a conventional motor vehicle. Forwardly directed longitudinal forces are applied to the protective housing  1  if the motor vehicle is involved in a rear-end crash. These forces are taken up by the transverse component  3   a  and passed further forward via the side parts  2   a ,  2   b . For this purpose, the protective housing  1  preferably is arranged behind a cross member, in order to take up the energy and to pass the energy on to corresponding longitudinal members LM of the motor vehicle MV. The side walls  2   a ,  2   b ,  3   a ,  3   b , the cover  4  and the base  5  preferably are formed from metal and are substantially planar so that energy from the crash is passed on in an optimum way. 
     A system of protective housings  1  can be provided to fit in differently dimensioned installation spaces of a plurality of different motor vehicles MV. The side walls  2   a ,  2   b ,  3   a ,  3   b , the cover  4  and the base  5  of the protective housings  1  in the system may all be the same. A cover cross member  8  that is dimensioned for the installation space of a particular motor vehicle MV then is selected and is secured to the standard cover  4 . The protective housing  1  then is secured in the installation space as described above.