Abstract:
This direct current power supply for electric vehicles includes a modular set of electrical storage batteries ( 16 ) which are electrically interconnected. The batteries are disposed in battery boxes ( 18, 20 ) which can be stacked to constitute a stack of modules ( 12, 14 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a direct current power supply for electric vehicles, of the type including a modular set of electrical storage batteries which are electrically interconnected. 
     It is in particular intended for supplying power to electric materials handling vehicles. 
     The power supplies of electric vehicles conventionally use a set of batteries each of which is capable of delivering a voltage of the order of 2 volts or a multiple of 2 volts, for example, the batteries being connected in series or in parallel inside a battery box accommodated in a housing provided for this purpose in the vehicles. 
     Obviously, to reduce the number of battery charging and discharging cycles, and consequently to increase their service life, it is necessary to use a large number of onboard batteries to provide sufficient electric power. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a power supply for electric vehicles which is capable of containing a large number of storage batteries in a small space. 
     It therefore consists in a power supply of the aforementioned type characterized in that the batteries are disposed in battery boxes which can be stacked to constitute a stack of modules. 
     Thus the general overall size of the power supply is adapted to suit the number of onboard batteries and unoccupied free space is therefore reduced. 
     Various embodiments of a power supply according to the invention can further include one or more of the following features, individually or in all technically feasible combinations: 
     at least one of the battery boxes includes a housing adapted to receive a battery charger for charging said batteries; 
     a portion of at least one of the battery boxes has a lateral wall delimiting a passage for cables for connecting the batteries; 
     the lateral wall of at least part of the battery boxes includes openings for ventilating the batteries; 
     the lateral wall of said battery boxes is higher than the batteries and the openings are delimited by cutouts formed in the projecting edge area of said lateral wall; and 
     the lateral wall of the battery boxes includes handling means adapted to cooperate with lifting equipment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages will emerge from the following description, which is given by way of example only and with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a power supply according to the invention, showing two modules in the process of being stacked; 
     FIG. 2 shows the power supply from FIG. 1 after stacking the modules; and 
     FIG. 3 is a perspective view of a particular module that can be incorporated into the power supply from FIGS.  1  and  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view of a power supply  10  in accordance with the invention for electric vehicles, shown during assembly. 
     For example, it can constitute a power supply for electric materials handling vehicles. 
     The figure shows that the power supply  10  includes an assembly made up of a lower module  12  and an upper module  14  each consisting of associated electrical storage batteries  16  each of which is capable of delivering a voltage equal to 2 volts, for example, the batteries being electrically connected in parallel or in series. 
     More particularly, the batteries  16  of the modules are disposed in a lower battery box  18  and an upper battery box  20 . 
     In the embodiment of the invention shown in this figure the power supply consists of the combination of the two modules  12  and  14 . 
     Of course, a greater number of such modules could be provided, depending on the onboard electrical power required by the vehicle. 
     As shown also in FIG. 2, the battery boxes  18  and  20  can be stacked. 
     The battery boxes  18  and  20  are each parallelepiped-shaped and their cross sections have substantially identical dimensions. 
     Also, the respective lateral walls  22  and  24  of the battery boxes  18  and  20  are higher than the batteries  16  and therefore extends upward beyond the top face of the batteries. 
     The large bottom face of the top battery box  20  has feet, like the foot  25 , adapted to nest in the upper edge area of the lateral wall  22  of the lower battery box  18 , these parts having complementary shapes. 
     The upper edge area of the wall  22  of the lower battery box  18  includes cutouts  26  for ventilating the batteries  16 . 
     As previously mentioned, the batteries in each battery box  18  and  20  are electrically interconnected in series or in parallel. 
     It can equally be seen that the modules are also connected two-by-two in series or in parallel. 
     If the batteries  16  are connected in parallel, the modules are connected in series. 
     On the other hand, if the batteries are connected in series, the modules are connected in parallel. 
     To this end, the wall  24  of the upper battery box  20  is shaped to provide a passage  28  for a module-connecting cable  30 . 
     Each battery box  18  and  20  is completed by handling means  32  consisting of openings adapted to cooperate with lifting equipment for mounting or demounting them. 
     Clearly, when stacked, the power supply just described has minimum overall dimensions given that unoccupied free space is reduced. 
     Also, connecting the supply  10  to the electric vehicle is greatly simplified because the modules are electrically interconnected and a single electrical connector  34  is therefore all that is needed to make the connection. 
     FIG. 3 shows that it is possible to provide, at one level, a battery box with a housing  36  adapted to receive a battery charger  38 . This greatly facilitates charging the batteries. 
     Note that the invention just described is not limited to the embodiment described. 
     In a variant mobile partitions could be provided in each battery box to separate the batteries or delimit the housing which receives the battery charger.