Abstract:
A box for a set of electric storage batteries includes at least two side walls extending generally parallel and defining between them a housing for receiving batteries. The side walls consist of an assembly of stacked modules each comprising a pair of wall elements mounted opposite each other.

Description:
BRIEF DESCRIPTION OF THE INVENTION 
   The present invention relates to a box for a set of electric storage batteries, particularly for an electric self-propelled vehicle, such as a maintenance machine and is particularly suitable for receiving batteries consisting of sealed elements of the gas recombination type. 
   DESCRIPTION OF THE RELATED ART 
   As is conventional, the power source used for electric vehicles is an assembly of batteries, each capable of delivering a voltage of the order of, for example, 2 volts. These batteries are placed in series or in parallel in a case placed in a housing provided for this purpose in the vehicle. 
   As will be appreciated, in order to reduce the number of battery charging and discharging cycles and so increase their life, a large number of batteries must be carried in order for there to be sufficient electric power available. 
   SUMMARY OF THE INVENTION 
   The document EP-A 0 575 060 discloses a box for a set of electric storage batteries, in which the side walls consist of an assembly of elementary stacked modules placed independently side by side. The document EP-A-0 405 803 discloses a box for the same use, which has no side walls and does not consist of an assembly of stacked modules, but of a pair of elements mounted opposite each other. These sets are stationary systems, not intended to be carried in an electric vehicle. They do not allow the rapid installation of several batteries at a time on the same pair of wall elements. 
   The object of the invention is to provide a battery box capable of containing a large number of electric storage batteries within a small space. 
   Its subject is therefore a box for a set of electric storage batteries comprising at least two side walls extending generally parallel and defining between themselves a housing for receiving the batteries, the box being characterized in that the side walls consist of an assembly of stacked elementary modules each comprising a pair of wall elements mounted opposite each other. 
   In this way the overall volume of the box is adapted to the number of batteries carried, so that the amount of unoccupied free space is reduced. 
   The box according to the invention may also comprise one or more of the following characteristics, taken in isolation or in accordance with all technically possible combinations:
         each wall element is in the form of a profile and comprises at least one folded edge that defines, jointly with a folded edge of the wall element mounted opposite it, a support for at least one row of batteries;   it also comprises battery retention means;   the retention means comprise a removable rod extending through the folded edges of the stacked wall elements;   it also comprises two end plates, each provided with fixing lugs for the wall elements;   the end plates are provided with openings for the ventilation of the battery elements;   the end plates are each provided with a handling point for engagement by a lifting appliance.       

   The invention also relates to a system of boxes for a set of electric storage batteries characterized in that it consists of a set of boxes as defined above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics and advantages will become clear in the course of the description, which is given purely by way of example and with reference to the accompanying drawings, in which: 
       FIG. 1  is an exploded perspective view of a box in accordance with the invention; and 
       FIG. 2  is a perspective view of a module used in the construction of the box shown in  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a battery box for an electric self-propelled vehicle, denoted by the general reference number  10  and positioned in what would be assumed to be a vertical position. 
   It is intended to receive a set of electric storage batteries, particularly sealed elements of the gas-recombination type, and to be placed in a housing provided for this purpose in a vehicle so as to serve as a source of electric motive power. 
   The box  10  comprises two side walls  12  and  14  spaced apart and defining between themselves a housing in which the batteries are placed. For example, each battery is capable of delivering a voltage of the order of 2 volts. 
   With reference also to  FIG. 2 , the side walls  12  and  14  are made up of an assembly of elementary interchangeable stacked modules, such as  16 . The number of modules used depends on the number of batteries to be carried. 
   Each module  16  comprises a pair of wall elements  18  and  20  arranged opposite each other in the assembled condition. 
   Each wall element is in the form of a U section whose arms  22  and  24  point inwards into the housing and permit stacking of the wall elements on top of each other while its base  26  is designed to form after assembly, and jointly with the other wall elements of the stack, the side wall proper of the box  10 . 
   More specifically, in the assembled condition, the lower arms  24  of the opposing wall elements  18  and  20  together form a support designed to receive one or more rows of electric storage batteries, these batteries being connected in series or in parallel. 
   Referring once again to  FIG. 1 , the box  10  also includes two end plates  28  and  30  attached to the free ends of the case composed of the assembled modules  16 . At least one end plate is attached removably for the batteries to be placed in or removed from the box  10 . 
   More specifically, each end plate  28  and  30  is provided with fixing lugs, such as  32 , arranged in pairs with one elementary module  16  attached to each lug. 
   It will be seen that the dimensions of the end plates  28  and  30  are such as to space the wall elements  18  and  20  of each module  16  in such a way that the ends of the edges  24  are spaced apart by a distance shorter than the length or width of the batteries. 
   The end plates  28  and  30  are also provided with openings such as  34 , to allow ventilation of the batteries placed in the box  10 , and with a handling point  36  designed to engage with a lifting appliance for raising the composite battery and setting it down. 
   Lastly,  FIG. 1  shows that the box  10  is completed by means of retention of the battery elements, in the form of a rod  38  inserted into orifices  40  ( FIG. 2 ) formed in the folded edges  22  and  24  of the wall elements. 
   Other kinds of appropriate means of retention can of course be envisaged. 
   In the description of the invention, it has been assumed that the wall elements are in the form of U sections. 
   It would however be possible, as a variant, to equip the box with modules having wall elements shaped differently e.g. in I sections, particularly in order to make a system of boxes by linking different boxes together. 
   It will be realized that the battery box according to the invention, as described above, which uses a set of interchangeable modules, enables the total volume to be adapted to the number of batteries it contains and therefore enables its volume to be reduced in the sense that the amount of unoccupied space can in this way be limited. 
   Should it be wished to increase the number of batteries carried, either longer modules should be used and the same end plates retained, or the number of stacked modules should be increased, and the box provided with higher end plates as a consequence. 
   If it is wished to provide a power source of very large capacity, it is possible to produce a system of boxes formed of an assembly of several boxes built as described earlier, in which the batteries are connected in series or parallel. In this arrangement, one or more modules may be common to all the boxes. 
   Furthermore, the edges of the wall elements allow a space to be defined between the racks of batteries which, in conjunction with the openings formed in the side plates, allows for cooling of the battery elements by ventilation. 
   It will be noted too that the invention greatly facilitates the operations of assembling and disassembling the batteries, in that all that is required is simply to take off one of the side plates and if necessary to remove the retention rod to enable battery elements to be inserted or removed. 
   Finally, it will be noted that the invention described above greatly facilitates the operations of battery maintenance, as the ventilation openings allow access to the battery elements. It is thus possible to measure the voltage available at the terminals of the battery elements without having to dismantle the box.