Abstract:
A protection device for a vehicle cab having a floor and two vertical side walls, the device including an armor plate below and substantially parallel to the floor of the cab, and deformable compartmented caissons connected between the floor and the armor plate and under the side walls of the cab, each compartmented caisson having buckleable walls dimensioned to buckle upon shock impact to the exterior of the armor plate.

Description:
This application is a national state entry of International Application No. PCT/FR2009/000684, filed Jun. 10, 2009 designating the U.S., which claims the benefit of French Application No. 08.03278, filed Jun. 12, 2008. 
     TECHNICAL FIELD OF THE INVENTION 
     The technical scope of the invention is that of floor protection devices for a vehicle cab and namely the floor of a military vehicle. 
     TECHNICAL BACKGROUND OF THE INVENTION 
     It is known to ensure the protection of a vehicle floor by placing an armour plate at a distance from this floor, such plate being fastened to the cab by deformable linking means such as flexible mounts. Patent DE19913845 discloses such a protection device. 
     The aim is to absorb part of the blast effect of the mine through the deformation of the armour plate whilst leaving a free space enabling the plate to deform without impacting the floor. The deformable linking means also absorb part of the energy of the shock. 
     However, the device described by this patent does not provide sufficient protection for the vehicle floor. The energy absorption capacities of the linking means are, in fact, insufficient. Furthermore, the solutions described by DE19913845 do not enable the free space located under the vehicle to be used to house equipment or components of the vehicle itself. 
     Patent DE19935573 discloses a protection device analogous to that proposed by DE19913845. This device comprises a deformable plate positioned under the vehicle floor to which is it connected by longitudinal beams with a layer of shock absorbing material being positioned between the beams and the vehicle. The protection capacities of such a device are also insufficient. Furthermore, the deformable plate is provided with mobility means that may be projected by the shock against the vehicle floor, and the beams are directly into contact with the floor supports and thus communicate the shock received directly to them. 
     DISCLOSURE OF THE INVENTION 
     The aim of the invention is to propose a device that firstly provides reinforced protection with a minimal mass for a vehicle floor, and secondly enables the free space under the vehicle floor to be used without deteriorating the protection efficiency. 
     Thus, the invention relates to a floor protection device for a vehicle cab, device comprising at least one armour plate that is arranged at a distance from the cab floor and which is connected to the latter by deformable linking means, device wherein at least one of the deformable linking means is constituted by a compartmented caisson, that is fastened to the cab on a substantially vertical lateral partition of the latter, the compartmented caisson comprising at least two walls that are substantially perpendicular to the armour plate and which are integral firstly with a lower wall on which the armour plate presses and secondly with an upper wall which presses on the cab, the walls having dimensions such that they buckle on impact. 
     According to a particular embodiment, the walls will be substantially perpendicular to a lateral partition. 
     The protection device may comprise at least two caissons integral with a same lower wall, the caissons being positioned at a distance from one another and separated by a space. 
     Advantageously, the caissons are further fastened to a same lateral plate, the caissons, the lateral plate and the lower wall thus forming a chamber. 
     The lateral plate may incorporate at least one opening giving access to the space separating the compartmented caissons. 
     The opening may be blocked by a hatch or cover, the space thus forming a storage case. 
     The floor protection device may comprise at least three caissons delimiting two spaces. 
     According to a particular embodiment, the lateral plate may form an angle with respect to the armour plate. 
     The chamber may furthermore be positioned such that it incorporates a plane upper rim which extends towards the outside of the vehicle beyond the lateral partition, such plane upper rim being parallel to or indistinguishable from the upper walls of the caissons. 
     According to a variant embodiment, at least one caisson is filled by an energy absorbing material. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention will become more apparent from the following description of different embodiments, such description being made with reference to the appended drawings, in which: 
         FIG. 1  is a side view of a light armoured vehicle equipped with a floor protection device according to a first embodiment of the invention, 
         FIG. 2   a  is a cross section view of the previous Figure along the plane referenced AA in  FIG. 1 , 
         FIG. 2   b  is a perspective view of the caisson alone, 
         FIGS. 3   a  and  3   b  are partial views of a second embodiment of the invention,  FIG. 3   b  being a perspective view of the chamber alone, 
         FIGS. 4   a  and  4   b  are partial views of a third embodiment of the invention,  FIG. 4   b  being a perspective view of the chamber alone.  FIG. 4   c  is similar to  FIG. 4   b , and additionally includes lateral plate  20 . 
         FIG. 5  is a cross section view of a light armoured vehicle equipped with a device according to a fourth embodiment of the invention, 
         FIG. 6  is a perspective view of two chambers according to a fifth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , a light armoured vehicle  1  comprises a cab  2  fixed to a chassis  3  equipped with wheels  4 . The inside of the cab can be accessed by a door  5  and it encloses seats  6  which are suspended from the cab roof by a support frame  7 . Such an arrangement is classical and enables the seats to be isolated from the cab floor  8 , thereby protecting the crew from the effects on the floor further to a mine exploding. 
     In accordance with the invention, a floor protection device  9  is provided that comprises an armour plate  10  (for example, of steel) that is positioned at a distance from the cab floor  8 . 
     The plate  10 , is fastened to the cab  2  by means of deformable linking means  11 . In accordance with the invention, at least one of the deformable linking means  11  (and preferably all the linking means  11 ) is constituted by a compartmented caisson.  FIGS. 1 and 2   a  show that the armour plate  10  is fastened by three caissons  11  arranged on each side of the vehicle. 
     As may be seen more particularly in  FIG. 2   a , the caissons  11  are arranged under a lateral partition  2   a  or  2   b  of the cab  2 , such partition being substantially vertical. Thus, the loads received by the armour plate  10  will be communicated to the cab, not to the floor  8 , but to the walls  2   a ,  2   b  that cannot be deformed so much. 
       FIG. 2   b  shows a perspective view of a caisson  11  according to this first embodiment of the invention. 
     By compartmented caisson, we mean a substantially parallelepipedic structure that incorporates at least two walls  12   a ,  12   b  that will be arranged substantially perpendicularly to the armour plate  10 . The walls  12   a ,  12   b  are integral with a lower wall  14  on which the armour plate  10  presses. The walls  12   a ,  12   b  are furthermore integral with an upper wall  13  that presses on the cab  2  and enables the device to be fastened to the latter. Each caisson  11  delimits an inner space  15  which is open laterally at each end of the caisson. 
     The walls  12   a ,  12   b  are thus substantially vertical and are furthermore dimensioned such that they buckle as a result of a shock transmitted by the armour plate  10  due to the detonation of an explosive device. This dimensioning will be performed classically by calculation depending on the material of the walls  12   a ,  12   b  and the expected level of shock. The buckling will be all the greater in that the wall is high with respect to its section. 
     The walls  12   a ,  12   b  delimit the inner space  15  of the caisson, they are furthermore also substantially perpendicular to the wall  12   a ,  12   b  in question of the cab  2 . 
     This orientation of the walls leads to their section being reduced thereby improving their deformation by buckling. Such a configuration is thus far from that of the longitudinal beams described by DE19935573. Indeed, the latter extend over the full length of the vehicle (thereby increasing the section of the vertical walls of the beams) and they are reduced in height. Such beams absorb little energy by deformation and communicate most of the shock received to the vehicle&#39;s structure. 
     The upper wall  13  will have drill holes enabling the caisson  11  to be fastened to the floor  8  or to the cab  2 . 
     The lower wall  14  will additionally have drill holes enabling the armour plate  10  to be fastened to the caisson  11 . 
     The caissons  11  are made of steel (depending on the level of protection required, they could also be made of another material, for example aluminium or a composite). The walls  12   a ,  12   b  ensure the rigidity of the caisson. When an explosive device or mine explodes under the vehicle  1 , the armour plate  10  is deformed by the blast effect. The free space  16  between the plate  10  and the floor  8  allows such a deformation without the shock being transmitted to the floor  8 . 
     The loads are communicated by the plate to the caissons  11 , which retransmit them to the walls  2   a ,  2   b  of the cab. However, the walls  12   a ,  12   b  will also deform by buckling. This deformation will consume part of the energy received but will above all attenuate the violence of the shock. Indeed, the energy of the explosion will be transmitted for a less brief duration which will reduce the stresses received by the vehicle and will attenuate the destructive effects on the cab. 
     It is possible for the caissons  11  to be given different shapes. 
       FIGS. 3   a  and  3   b  show another embodiment in which a single caisson  11  is positioned on either side of the vehicle but which has a length that is substantially equal to that of the armour plate  10 . 
     To give the caisson  11  the properties of rigidity/deformability necessary for it to ensure its function of attenuating the shocks, partitions  17  parallel to walls  12   a ,  12   b  are arranged inside it (here there are four partitions). The partitions  17  will, for example, be welded to the upper  13  and lower  14  walls of the caisson. 
       FIGS. 4   a  and  4   b  show another embodiment in which three caissons  11  are implemented, all integral with a same lower wall  18 . 
     It is no longer necessary, in this case, to provide a specific lower wall  14  for each caisson  11 . The lateral walls  12   a ,  12   b  and upper wall  13  thus form a U-shaped structure which will, for example, be welded to the common wall  18 . When a mine is ignited, the shock received by the armour plate  10  will thus be transmitted to the wall  18  which will ensure the distribution of the shock over the different caissons  11 . 
     With such an embodiment, the caissons  11  will be positioned at a distance from one another. Two neighbouring caissons  11  are thus separated by a space  19 . 
     Advantage may be taken of these spaces  19  to constitute storage areas to be used by the vehicle&#39;s crew. 
     These spaces  19  may also house the organs of the vehicle, for example an exhaust silencer or batteries. 
     We note that it would also be possible in the embodiment shown in  FIGS. 3   a ,  3   b  to use the spaces inside the caisson  11  (between partitions  17 ) by way of storage areas. 
       FIG. 4   c  differs from  FIG. 4   b  in that the caissons  11  are also fixed to a same lateral plate  20  which here is perpendicular to the lower wall  18 . The caissons  11 , the lateral plate  20  and the lower wall  18  form a chamber  21 . 
     The vehicle thus incorporates a chamber  21  on each side. Each chamber constitutes a compact assembly incorporating the caissons  11  to absorb the shock wave transmitted by the armour plate  10 . The lateral plate  20  constitutes another deformable element that completes the caissons  11 . It also enables the chamber to be closed thus insulating the inner spaces  19  from the exterior of the chamber. Openings will be advantageously provided in the lateral plate  20  which will carry closing covers to access the internal storage areas  19 . 
       FIG. 5  differs from the previous embodiment in that the caissons  11 , grouped into chambers  21 , incorporate a lateral plate  20  that forms an angle with respect to the armour plate  10 . 
     Such an arrangement gives an overall deflector shape to the device  9 , such shape ensuring a deviation of the blast received from a mine when the latter is in the vicinity of one of the rims of the armour plate  10 . 
     Furthermore,  FIG. 5  shows that each chamber  21  is positioned such that it incorporates a plane upper rim  22  that extends towards the outside of the vehicle beyond the lateral partition  2   a ,  2   b.    
     This rim  22  is formed here of part of the upper wall  13 . It constitutes a step to facilitate access to the vehicle. 
       FIG. 6  shows another embodiment of the chambers  21  according to the invention. In accordance with this embodiment, the lateral plate  20  of each chamber is once again inclined with respect to the armour plate  10 . 
       FIG. 6  shows that the lower wall  18  has two rows of holes to enable the armour plate (not shown in  FIG. 6 ) to be fastened. Furthermore, the upper walls  13  ( 13   a ,  13   b  and  13   c ) of the caissons have holes to allow the passage of screws to fasten the device to the cab. 
     We note that in this embodiment, the caissons  11  are not all of the same shape. The end caissons  11   a  and  11   c  have lateral walls  12   a ,  12   b  that are not parallel. At least one wall ( 12   a ) is, however, still perpendicular to the lower wall  18  (and to the armour plate). The other wall  12   b  is slightly inclined with respect to the lower wall  18 . Such an arrangement is intended to adapt the external shapes of the front  11   a  and rear  11   c  caissons (and thus of the chamber  21 ) to the structure of the vehicle. The walls  12   a  and  12   b  nevertheless ensure resistance to deformation for the caissons in question. 
     We note also on this Figure that the caissons  11  incorporate an opening  24  in certain of their lateral walls  12 . These openings help to lighten the structure of the chambers and furthermore provide an access for the fastening screws enabling the upper faces  13  of the caissons to be joined to the vehicle cab. 
     This Figure shows that the lateral plates  20  incorporate openings giving access to the space  19  between the caissons  11 . These openings are block by hatches  22  fitted with hinges and locks (not shown).  FIG. 6  lastly shows that each chamber  21  here incorporates an upper rim  22  that completes the closing of the spaces  19 . This rim  22  is parallel to the upper walls  13  of the caissons and is located on a plane slightly above the plane of the upper walls  13 . The rim thus forms a step giving access to the vehicle cab. 
     In all of the embodiments previously described, the caissons  11  are empty. It is possible, by way of a variant, to put a deformable material inside one or several caissons able to complete the absorption of the impact energy. For example, deformable foam, for example metallic foam (such as aluminum foam) may be placed in the caissons. Sand or else a metallic or composite material cell structure, like a honeycomb, may be put in the caissons  11 . It is also possible to install a shock absorbing material between the armour plate  10  and the lower wall  14  and/or between the upper wall  13  and the floor of the cell  8 .