Abstract:
A blast dissipation device for an armored vehicle includes a first absorption system and a second absorption system that are usable to dissipate initial blast forces exerted upon an underbelly of the vehicle caused by, for example, detonation of an IED below the vehicle. The second absorption system has a delayed reaction to forces exerted upon the underbelly of the vehicle. The first absorption system reacts more quickly and serves to dissipate initial forces until the second absorption system is activated to dissipate the remaining forces.

Description:
TECHNICAL FIELD 
       [0001]    The present device relates to a blast dissipating system for improving the protection of a vehicle, occupants lower extremities. More specifically, the device aides in the dissipation of shockwaves, displacement and other forces exhibited on the underbelly of a vehicle caused, for example, by detonation of an explosive device below the vehicle. 
       BACKGROUND 
       [0002]    Armored vehicles are threatened by improvised explosive devices (IEDs) designed to cause harm to the vehicle and its occupants. IEDs are typically one or more grouped artillery shells redeployed and detonated in an effort to inflict casualties. These explosive devices when detonated beneath a floor of a vehicle, these explosive devices often create localized deformation of the floor of the vehicle thereby transmitting large vertical loads onto the lower extremities of occupants of the vehicle. For example, detonations below the underbelly of an armored vehicle may cause the vehicle floor to accelerate at 100G or more and reach velocities of 7 to 12 m/s over a time period of 3 to 5 msec. These high rates of acceleration and velocity transmit large mechanical forces on the lower extremities of the occupants within the vehicle cabin. 
         [0003]    Armor countermeasures typically consist of heavy metal plates placed between the threat and the vehicle in such a way as to resist hull breach and aggressive floor accelerations. These heavy metal plates also work in concert with layers of additional metal, ceramic, composite or plastic materials designed to prevent lethal high velocity artillery shell fragments from entering the vehicle. The heavy metal plates are typically mounted to the underside of the vehicle in a V-shape in an effort to take advantage of shape efficiency and deflection characteristics when presented with incoming pressure and fragmentation. Carrying a heavy blast and fragment resistant hulls results in significant performance disadvantage to the vehicle in terms of reduced fuel economy, lost cargo capacity and increased transportation shipping costs. 
         [0004]    The present device usable, for example, in a personnel cabin of a vehicle, includes a two stage dissipating system for dissipating the blast forces from an explosive device. The device includes an absorbent mat, a suspended floor, and an air bag, which is deflated through use of a blast sensing apparatus. The absorbent mat, air bag and suspended floor help improve the dissipation of forces exerted on the underbelly of the vehicle while avoiding the negative tradeoffs of alternative designs. 
       SUMMARY 
       [0005]    There is disclosed herein a system and method, each of which avoids the disadvantages of prior systems and methods while affording additional structural and operating advantages. 
         [0006]    Generally speaking, a blast dissipating device for use in protecting occupants in a vehicle is disclosed. The device is provided as a separate device that may be installed into the floor of a vehicle. The device is provided with a two-stage absorption system including a first and a second absorption system, and is designed to allow for increased relative motion between the body of the vehicle and the lower extremities of occupants within the vehicle. That is, the device allows the body of the vehicle, such as the floating floor, to move a greater distance before exerting a force on the lower extremities of the occupants of the vehicle. 
         [0007]    In an embodiment, a blast dissipating device usable within the interior of a personnel cabin of a vehicle is disclosed. The device comprises a first absorption system responsive immediately to deformation forces exerted on an underbelly of the vehicle to dissipate the forces, and a second absorption system responsive after the first absorption system to further dissipate the forces. In general, the second absorption system may be initiated after the first absorption system has dissipated the maximum amount of energy it is capable of dissipating. Alternatively, the second absorption system may be initiated before the first absorption system has reached a maximum level of dissipation. 
         [0008]    In another embodiment, first absorption system is an absorbent mat, while the second absorption system is an air bag system. The air bag system is a pneumatic air bag system. The pneumatic air bag system comprises a bladder, at least one input valve, at least one release valve, and a blast sensing diaphragm. 
         [0009]    In another embodiment, the diaphragm deforms in response to a force exerted upon the underbelly of the vehicle to a predetermined limit, activating the at least one release valve to release air from within the bladder to help dissipate the forces exerted upon the underbelly of the vehicle. 
         [0010]    A method of absorbing at least a portion of a force exerted upon the underbelly of a vehicle, is disclosed. The method comprises the steps of activating a first absorption system to dissipate an initial force exerted upon the underbelly of the vehicle; and, activating a second absorption system to dissipate the remaining force exerted upon the underbelly of the vehicle, wherein the second absorption system is activated after the first absorption system. 
         [0011]    In yet another embodiment, the method comprises first stage energy absorption system via an energy absorbing floor mat. The second stage absorption system comprises deforming a diaphragm of an air bag system, activating a release valve of the air bag system, and releasing air from within a bladder of the air bag system to lower an air pressure of the air bag system, and wherein the release valve is activated after the energy absorbing mat has been at least partially deformed. 
         [0012]    These and other features and advantages of the present device and methods can be more readily understood from the following detailed discussion with reference to the appended drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a vehicle with the present blast dissipation device installed therein; and, 
           [0014]      FIG. 2  is a schematic exploded view of an exemplary embodiment of a blast dissipation device. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring to  FIGS. 1 and 2 , there is illustrated an exemplary embodiment of a blast dissipating device and system or safety floor, generally designated by the numeral  10 , as well as the components thereof. The device  10  is designed for use as a blast dissipation system in the underbelly or floor of a personnel cabin  12  of a vehicle  14 , particularly a military vehicle, which is used in war-zones for transporting personnel or cargo. This device  10  will allow more relative motion between the vehicle floor structure and the vehicle occupants&#39; lower extremities, reducing injury to the occupants. 
         [0016]    As shown in  FIG. 2 , the device  10  includes an air bag  20  retained in an air bag housing  22 , such as a casing or a tub. In various exemplary embodiments, the air bag  20  may be a pneumatic air bag. Additionally, the air bag  20  will include one or more valves, such as input and bleed valves, which are usable to vary the pressure of the air within the air bag when the air bag is activated, as will be described later. In general, the air bag  20  is maintained at a desired air pressure when the device  10  is installed in a vehicle by inputting air or bleeding air to increase or decrease, respectively, the air pressure based on changes in environmental conditions. For example, as the temperature of the air in the air bag  20  increases or decreases, the air pressure will change and air will need to be added or released to return the air pressure to the desired value. 
         [0017]    The device  10 , including the air bag  22  housing and air bag  20  having an internal bladder  21 , is installed on the vehicle  14 , for example to a vehicle floor pan  15 . The air bag housing  22  includes one or more mounting holes  30  usable to locate and attach the air bag housing to the vehicle false floor pan  15   a  separated from the belly floor pan  15 . For example, the mounting holes  22  are usable to install bolts, screws, other fasteners, or the like to mount the air bag housing to the vehicle false floor pan. While the bottom of the vehicle may be subject to the brunt of a blast as the vehicle travels over an explosive device, it should be understood that the air bag housing  22 , and the associated air bag  20  may be installed in any area of the vehicle and cabin space, not just the floor, to provide the desired blast dissipation protection. 
         [0018]    The air bag housing  22  includes a flange  26  around the outer rim of its top surface  28 . This flange  26  provides mounting points or mounting holes  30  for a suspended floor  32 . The air bag housing has guides  34   a  that mates with guide pins  34  provided on the suspended floor  32 . By mating the guide pins  34  with the guides  34   a,  the floor  32  can be positioned in a desired orientation and allowed to move or float freely in the vertical direction while otherwise maintaining its horizontal and rotational orientation. 
         [0019]    In the event of malfunction in the system securing the suspended floor  32  to the retaining plate  36  is accomplished by one or more locking brackets  38  along with one or more locking pins  39 . The locking brackets  38  extend through apertures  36   a  in the retaining plate  36  and mate with the locking pins  39  such that the suspended floor  32  is secured to the retaining plate  36 . For example, if the air bag  20  becomes damaged and cannot be inflated to press the suspended floor  32  against the retaining plate  36 , the locking brackets  38  and pins  39  may be utilized to ensure that the suspended floor remains in a desired position against the retaining plate for continued service of the vehicle. 
         [0020]    An absorbent mat  40  is provided on top off the suspended floor  32  and its retaining plate  36 . The absorbent mat  40  can be any commercially available blast mitigation floor mats Ex. SKYDEX floor mats. 
         [0021]    In a blast event the high accelerations are experienced by the floor pan in extremely short time of the order of 3 Msec. to 5 Msec. The suspended floor system requires some time to sense the event via diaphragm  44  and react to the event via pressure valve  42  to deflate the air from the air bag to lower the suspended floor  32  absorbing the energy while displacing. During the initial phase 3 Msec. to 5 Msec. the suspended floor  32  still compressed against retaining plate  36  provides a stable floor against to which the energy absorbing floor mats can react providing the initial or first stage energy absorption via compression and/or collapse of the energy absorbing floor mat  40  through its thickness. Thus, the energy absorbing mat  40  provides the first stage of protection for the occupants of the vehicle from the blast forces exerted on the vehicle floor pan  15  or  15   a.    
         [0022]    Although the absorbent mat  40  provides an initial level of protection against a blast, it is the activation of the air bag  20 , which provides a significant second level of protection to the vehicle occupants. Activation of the air bag  20  is accomplished through a series of valves, specifically an input valve (not shown), which initially fills the air bag bladder  21  with air, and an output or check valve  42 . The check valve or valves  42  are one-way valves that bleed air from the air bag at regulated rate when the valve is activated. Activation of the air bag  20  in the event of a blast is accomplished by a blast sensing apparatus  44 . The blast sensing apparatus  44  is a diaphragm connected to the check valve. The sensing apparatus  44  and/or a diaphragm are located under the belly of the vehicle. There can be multiple diaphragms fairly distributed under the belly to sense the blast event around any location under the belly. The diaphragm  44  reacts to a blast force against the floor pan  15  of the vehicle by deforming; the deformation of this diaphragm activates the check valve  42  releasing the air from the airbag  21 . Because the check valve  42  is a one-way valve, it allows the air to move in only a single direction out of the air bag. It should be understood that multiple check valves may be incorporated as one or more of the bleed valves, and as well, there may be other methods of activation. Additionally, a monitoring system (not shown), manual or electronic, that controls the air pressure of the air bag, may also be included in the present system for regulating the air pressure within the air bag. 
         [0023]    In operation, the various components of the blast dissipation device  10  work separately and in conjunction to dissipate at least some of the energy exerted on the underbelly of a vehicle cause by, for example, the explosion of an IED below the vehicle. In various exemplary embodiments, when an IED, or similar explosive device, is detonated below the vehicle, the force of the explosion causes the floor pan  15  of the vehicle  14  to deform. This deformation in turn forces the safety floor against the lower extremities of any occupants of the vehicle. The absorbent mat  40 , acting as a first absorption system, deforms to help dissipate the initial force being exerted on the lower extremities of the occupants and thereby reduce the likelihood of injury to the occupants. 
         [0024]    As the floor pan continues to deform, the diaphragm  44  likewise deforms. After the diaphragm  44  has deformed to a sufficient level, it will activate the check valve  42  and initiate a controlled release of the air pressure within the air bag  20 . This controlled release of air from the air bag can be controlled by adjusting the flow rate of air through the check valve  42 , thereby adjusting the level of deformation of the diaphragm that is necessary to activate the check valve, or otherwise adjusting the system. 
         [0025]    The controlled release of the air pressure within the air bag  20 , which acts as a second absorption system, helps dissipate the energy exerted on the floor pan such that the energy is not transferred onto the occupants of the vehicle. The floor pan  15  is thus allowed to move a greater distance relative to the occupants of the vehicle without causing harm to those occupants. 
         [0026]    It should be appreciated that the above-referenced forces may include general deformation forces, localized deformation forces, general displacement forces, localized displacement forces, or any other force that may be exerted upon the underbelly of a vehicle. 
         [0027]    It should also be appreciated that, while the above discussion is related to deformation forces caused by, for example, IED explosions, the invention may be usable to dissipate other forces, such as, for example, blunt forces impacts, grenade detonations, small arms fire, and any other force that may be exerted upon the underbelly of a vehicle.