Abstract:
A cushion for use in a helmet or body armor to mitigate shock loads (i.e. blasts or blunt impact) against the human body includes a matrix having a plurality of fluid pockets. The fluid pockets themselves are either deformable, or they can be reconfigured (e.g. emptied) and are, therefore, connected in fluid communication with an empty receiver pocket. In the latter case, a vent connects each fluid pocket to at least one receiver pocket, and a valve is imbedded into the vent to control fluid flow through the vent. In either case, when the cushion receives a shock load, fluid in the cushion is transferred to reconfigure the cushion for mitigation of the resultant forces.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention pertains generally to systems for protecting the body from shock loading due to a violent impact or blast. Shock loading is the very rapid application and short duration of applied force. More particularly, the present invention pertains to cushions for mitigating the adverse effects that can result from forces to the head and body that are caused by shock loads. The present invention is particularly, but not exclusively, useful as a protective cushion that incorporates fluid transfer, fluid compression, and membrane deformation techniques, into a helmet, vest, shoes, or clothing, for mitigating the injury effects of shock loadings. 
       BACKGROUND OF THE INVENTION 
       [0002]    A primary objective of any protective gear is to somehow mitigate the adverse effects that shock loading can have on the body. Low level impacts to the head can produce mild Traumatic Brain Injury (mTBI), while high level impacts to the head can produce massive internal injury and death. Impacts to the torso can produce lung contusion, pneumothorax (collapsed lung), heart contusion, and rupture of internal organs. Impacts to the extremities can lead to traumatic amputation. 
         [0003]    In a combat environment, head protection is particularly important and is underscored by the fact fifty-nine percent of blast-injured patients develop some form of brain injury. These brain injuries are, unfortunately, in addition to other injuries that may also be sustained. Similar brain injuries can occur in sports. Analyses of helmet impacts in football have produced data that indicate that an acceleration of 106 g&#39;s is estimated to produce mTBI, 80% of the time, while an acceleration of 66 g&#39;s is estimated to produce mTBI 25% of the time. Extrapolation of these data leads to the conclusion that accelerations must be less than 50 g&#39;s to be safe. It is the objective of effective head gear to transmit the impact force in such a way as to minimize the head acceleration. 
         [0004]    Impact to the torso can produce significant internal injury. Even when the person is wearing personal body armor (military or law enforcement) that provides protection from the penetration of bullets and fragments, blunt trauma can occur from the inward deformation of the armor. Currently, armor designs are limited by these deformations. Research shows that these injuries are caused by the very short time duration that the impact is delivered to the body. It has been estimated that if the chest wall is accelerated to an inward velocity of 20-30 m/s, even for a very short time which produces a very small deformation, death can occur. Smaller chest velocities produce lesser forms of injury. Although a absolutely safe level has not been established, it is probably less that 8 m/s. The body can withstand, without injury, greater deformation if it applied over a long period of time. It is the objective of effective body protection gear to transmit the impulse of the impact force in such a way as to maximize the duration of the impulse delivered to the torso and, therefore, minimize the chest wall velocity. 
         [0005]    To put this in proper perspective, survivable explosions from an IED might produce blast loading with durations from less than one millisecond to as much as 10 milliseconds. The impact from the deformation of body armor has a duration ranging from less than one millisecond to a few milliseconds. The impact of helmets in sports or in a motorcycle accident is, again, only a few milliseconds. Mitigation of a shock loading is done typically by positioning a protective system between the impact source and the part body that is to be protected. The protective system must, therefore, act extremely quickly to distribute the impact force and duration over the largest area and largest duration to achieve the greatest effectiveness. 
         [0006]    The efficacy of the protective system depends on several different factors, the more important of which include: 1) material characteristics of the protective body; 2) structural configuration of the protective body; and 3) attributes of the applied impact force. Of these, only the first two factors (material characteristics and configuration) can be controlled; the attributes of the applied impact force depend on the application. The concern of the present invention is toward the design of protective systems to protect the head, torso, and extremities from shock loading, that is, from large loads that occur with short time durations. These protective systems are judged on their ability to lower head acceleration, chest velocity, and other correlates of internal injury. 
         [0007]    Open and closed cell foam or liquid or gas-liquid gels are commonly used as cushioning material in headgear or behind body armor or in shoes. These materials, especially the foams, are designed to provide a certain crushing load when stressed at a certain rate. Although these materials may be efficacious for some types of force loadings, they do not provide the theoretical optimum protection possible and have characteristics that lose their cushioning ability as the duration of the loading decreases. For the shock loading of interest, other materials, with an appropriate structural configuration, are more effective. 
         [0008]    In light of the above, it is an object of the present invention to provide a cushioning device for mitigating shock loads on a human body that incorporates the dynamic properties of fluid density and compression, membrane characteristics and response, and fluid motion and exchange. Another object of the present invention is to provide a cushioning device for mitigating shock loads that can be specifically configured (i.e. customized) to conform with different types of body regions (headgear, body armor shoes, etc,) and to respond to different shock loading magnitudes and rates, for different applications. Still another object of the present invention is to provide a cushioning device for a protective headgear or body armor that provides resistance against unwanted motion and affords protection against shock loads. Yet another object of the present invention is to provide a cushioning device for mitigating shock loads on the head and body of a human being that is comfortable to wear, is relatively simple to manufacture, and is comparatively cost effective. 
       SUMMARY OF THE INVENTION 
       [0009]    In accordance with the present invention, a protective device for mitigating the adverse effects of shock loading against the head and body of the wearer, employs a cushion that includes a matrix of fluid pockets. As envisioned for the present invention, both the matrix and the fluid pockets are deformable. Specifically, deformation of the cushion results from the forced transfer of fluid within the cushion, from the compression of the fluid, and/or the deformation of the membrane containing the fluid. In particular, this deformation can be accomplished either by reconfiguring the fluid pockets or by transferring fluid in a fluid pocket, from one location to another location. 
         [0010]    For a preferred embodiment of the present invention, a plurality of fluid pockets is formed by a viscoelastic membrane and is arranged in a matrix. Similarly, a plurality of empty receiver pockets is formed in the matrix. Further, vents are formed in the membrane matrix to connect each fluid pocket in fluid communication with at least one receiver pocket. A valve or baffle that is imbedded in each vent can then be used to control the flow of fluid through the vent. For the present invention, the viscoelastic material that is used for the membrane is preferably a semicrystalline polymer, such as polyurethane-PU or polyethylene-PE. 
         [0011]    As envisioned for the present invention, the valves that are imbedded in the vents can be of several types. One possibility is to use one-way valves that will open whenever a pressure in the respective fluid pocket “p f ” exceeds a predetermined value. In this case, the valve may actually rupture at “p f ” for a one-time use of the cushion. Alternatively, the valves may be two-way valves. In this case, each valve will permit fluid to flow from a fluid pocket into a receiver pocket when pressure in the fluid pocket exceeds “p f ”. For the two-way valve, however, fluid will back flow into the fluid pocket, from the receiver pocket, when a pressure in the receiver pocket “P r ” is greater than “p f ”. 
         [0012]    For an alternate embodiment of the present invention, there are no receiver pockets; only fluid pockets. In this embodiment, the matrix itself (e.g. membrane) deforms. This causes the fluid pockets to be reconfigured, to thereby absorb the effects of an external force. 
         [0013]    Insofar as fluids for use with the present invention are concerned, the present invention envisions using either a liquid or a gas. Generally, the choice will depend on the application. If a gas is to be used, expansion and contraction of the gas may be significant over a range of operational temperatures between −40° F. and 160° F. The consequent volume differential may be as much as 25%, and should be accounted for. On the other hand, if a liquid is to be used, it must have a boiling temperature above the operational temperature range, and a freezing temperature that is below the range. 
         [0014]    An important aspect of the present invention is that the configuration of fluid pockets, and receiver pockets if used, can be customized. Stated differently, the cushion may have any of several different configurations, arrangements or presentations. Further, based on material selection for manufacture of the cushion and the consequent operational thresholds for valves, baffles and membrane expansions, it can, in effect, be “tuned” to have a desired protective response to a blast impact. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
           [0016]      FIG. 1  is a perspective schematic view of a protective cushion in accordance with the present invention, with the cushion shown having a fluid transfer system incorporated into a helmet for use as a head protector; 
           [0017]      FIG. 2  is a view of the cushion as seen along the line  2 - 2  in  FIG. 1  with portions of the helmet removed for clarity; 
           [0018]      FIG. 3A  is a cross section view of a portion of the cushion as seen along the line  3 - 3  in  FIG. 2  before a blast impact; 
           [0019]      FIG. 3B  is a view of the cushion as seen in  FIG. 3A  after a blast impact; 
           [0020]      FIG. 4A  is a schematic plan view showing an alternate embodiment of a fluid system for use in the cushion of the present invention, with the fluid system shown before a blast impact; 
           [0021]      FIG. 4B  is a view of the fluid system shown in  FIG. 4A  with partial fluid transfer, after a blast impact; 
           [0022]      FIG. 4C  is a view of the fluid system shown in  FIG. 4A  with complete fluid transfer, after a blast impact; 
           [0023]      FIG. 5A  is a schematic plan view showing another alternate embodiment of a fluid system for use in the cushion of the present invention, with the fluid system shown before a blast impact; 
           [0024]      FIG. 5B  is a view of the fluid system shown in  FIG. 5A , after a blast impact; 
           [0025]      FIG. 6A  is a cross section view of yet another alternate embodiment of a fluid system for use in the cushion of the present invention, as would be seen along the line  3 - 3  in  FIG. 2  before a blast impact; and 
           [0026]      FIG. 6B  is a view of the fluid system shown in  FIG. 6A , after a blast impact. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Referring initially to  FIG. 1 , a device for mitigating blast impacts in accordance with the present invention is shown and is generally designated  10 . As shown, the device  10  includes a cushion  12  that has been incorporated as part of a helmet  14  to provide head protection. More specifically, for the embodiment of the present invention shown in  FIG. 1 , the cushion  12  is configured as a matrix  16  having a plurality of rings  18 , of which the rings  18   a  and  18   b  are exemplary. The matrix  16  is also shown to have a plurality of strips  20 , of which the strips  20   a  and  20   b  are exemplary. As will be appreciated by the skilled artisan, the rings  18  and strips  20  can be used together, in combination, or individually. 
         [0028]    Referring now to  FIG. 2 , the rings  18  and strips  20  of the cushion  12  are shown, in detail, to include a plurality of fluid pockets  22  that are interconnected with a plurality of receiver pockets  24 . The fluid pockets  22   a  and  22   b,  and the receiver pockets  24   a  and  24   b  that are shown are only exemplary.  FIG. 2  also shows that the cushion  12  is positioned inside the helmet  14  to protect the head  26  of a user. This also is exemplary. Although the cushion  12  shown in  FIG. 2  is being used for protection of a head  26 , it is to be understood that cushions  12  can be uniquely configured and used for protection of other body parts, such as the torso, legs, arms and neck. 
         [0029]      FIGS. 3A and 3B  best show the structural and functional interaction between a fluid pocket  22  and its associated receiver pockets  24 . More specifically, in  FIG. 3A , the fluid pocket  22   a  is shown to be filled with a fluid  27  having a fluid pressure “p f ”. Normally (i.e. before a shock loading), p f  will be zero. Further,  FIG. 3A  shows that a vent  28   a  is provided to establish fluid communication between the fluid pocket  22   a  and the adjacent receiver pocket  24   a.  Also, a valve  30   a  is shown imbedded into the vent  28   a.  Similarly, a vent  28   b,  in combination with a valve  30   b,  is provided to establish fluid communication between the fluid pocket  22   a  and the adjacent receiver pocket  24   b.  As intended for the present invention, the cushion  12  will include numerous such fluid connections throughout its matrix  16 . As implied above, the actual number and placement of the rings  18  and strips  20  is a matter of design choice. 
         [0030]    In the event of a blast (shock loading)  32  (or a blunt force impact), indicated by the arrow in  FIG. 3A , the helmet  14  will act as a plate member having an impact surface  34  and a force transfer surface  36 . Structurally, the helmet  14  will transfer the effect of the blast  32  to the fluid pocket  22   a.  For fluid pocket  22   a,  the result will be an increase in pressure (p f ) on fluid  27  in the fluid pocket  22   a.  Additional fluid pockets  22  will, of course, also be affected. And, each fluid pocket  22  will respond substantially the same as described here for the fluid pocket  22   a.    
         [0031]    Functionally, due to the over-pressure of “p f ” that results in fluid pocket  22   a,  in response to the blast  32 , the valves  30   a  and  30   b  will open. This permits fluid  27  to flow from fluid pocket  22   a  into the receiver pockets  24   a  and  24   b  through respective vents  28   a  and  28   b.  Consequently, as shown in  FIG. 3B , the receiver pockets  24   a  and  24   b  fill with fluid  27 . As the receiver pockets  24   a  and  24   b  fill with fluid  27 , a pressure “P r ” is established on the fluid  27  in the receiver pockets  24   a  and  24   b.  As intended for the present invention, this transfer of the fluid  27  from the fluid pocket  22   a  into the receiver pockets  24   a  and  24   b  mitigates the adverse effects of the blast  32  on the head  26 . If the valves  30   a  and  30   b  are one-way valves, the cushion  12  will remain in the configuration shown in  FIG. 3B  after the effects have subsided. In this case, P r  will, most likely, equal p f . On the other hand, if the valves  30   a  and  30   b  are two-way valves, fluid  27  can back flow from the receiver pockets  24   a  and  24   b  into fluid pocket  22   a,  as long as p r  is greater than p f . 
         [0032]    As indicated above, the fluid transfer system described above with reference to  FIGS. 2 ,  3 A and  3 B is but one embodiment envisioned for the present invention. Other systems are envisioned. Furthermore, it is to be appreciated that elements of one system can be incorporated into another. The result here, is that fluid systems can be individually customized for the cushion  12 . For this purpose, the specifics of a cushion  12  for the device  10  will be determined, in large part, by the particular application. With this in mind, several structural variations for fluid systems that can be incorporated into a cushion  12  are envisioned for the present invention. 
         [0033]    In  FIGS. 4A-C  a fluid system, generally designated  38 , is shown to include a central fluid pocket  40  that is surrounded by numerous receiver pockets  42 / 44 . Specifically, the receiver pockets  42 / 44  are positioned along the periphery  46  of the central fluid pocket  40 , and are connected for fluid communication with the pocket  40  via a respective valve/baffle  48 . The receiver pockets  42   a,    42 b and  44   a,    44   b  are exemplary. For this particular fluid system  38 , the receiver pockets  42  are designed to have a higher modulus of elasticity than do the receiver pockets  44 . Accordingly, the receiver pockets  44  will expand under a relative lower pressure (compared to receiver pockets  42 ). Thus, fluid  27  can transfer from the fluid pocket  40  into the receiver pockets  44  first, before transferring into the receiver pockets  42 . Indeed, the receiver pockets  44  may expand, without any expansion of the receiver pockets  42  (see  FIG. 4B ). A higher pressure (e.g. greater impact from blast  32 ), however, may cause all receiver pockets  42 / 44  to expand (see  FIG. 4C ). The receiver pockets might each be made of different material so that the transfer of fluid occurs at different times, at different pressures, and with different effects on the cushioning body. In this way, the cushioning load can be customized to match any application. 
         [0034]    Till now, the fluid systems considered for the present invention (i.e. shown in FIGS.  3 A/B and FIGS.  4 A/B/C) have relied on the transfer of a fluid from a fluid pocket into a receiver pocket.  FIGS. 5A and 5B , however, show a fluid system in which there are no receiver pockets. Only a single fluid pocket  50  is involved. As will be appreciated by the skilled artisan, however, a plurality of similar fluid pockets  50  can be provided in a same matrix  16 , and can be arranged therein in a variety of configurations. In any event, as envisioned for the present invention, a fluid pocket  50  is preferably manufactured with a region  52  made of material having a different modulus of elasticity than another region  54 . More specifically, this elasticity differential can be employed for the purpose of predicting and controlling the deformation of the fluid pocket  50  in response to shock loading  32 . For instance, as shown in FIGS.  5 A/B, with properly selected materials, the fluid pocket  50  ( FIG. 5A ) will predictably reconfigure to the fluid pocket  50 ′ ( FIG. 5B ). 
         [0035]    In  FIGS. 6A and 6B  yet another type of fluid system for use in the cushion  12  of the present invention is shown. In this embodiment, a boundary member  56  is positioned opposite a plate member (e.g. helmet  14 ). As shown for this embodiment of cushion  12 , a membrane  60  forms a plurality of fluid pockets  62  on the boundary member  56 . Note: for most embodiments of the present invention, the boundary member  56  will be made of the same material as is used for the membrane  60 . In any event, for the embodiment shown in  FIGS. 6A and 6B , the fluid pockets  62  establish a network of fluid escape channels  64 . Importantly, each fluid pocket  62  is designed to have a weak point  66 . Specifically, this weak point  66  is engineered to rupture when an overpressure (e.g. blast  32 ) is caused on the plate member (helmet  14 ). The intended result is for fluid to transfer from the fluid pockets  62  into the fluid escape channels  64 . 
         [0036]    For all embodiments of the fluid systems disclosed above, the present invention envisions a mitigation of the forces imposed by a shock loading  32  against a human body. Specifically, the energy that is absorbed by the cushion  12 , after an impact from blast  32 , is used up in the fluid transfer process. In the case of the embodiment shown in  FIGS. 5A and 5B , the energy is dissipated by the transformation of the fluid pocket  50 . For purposes of the present invention, as mentioned numerous times herein, the particular embodiment of the fluid system that is used for construction of the cushion  12 , and its configuration, are primarily design considerations. Further, although the specific materials used for construction of the cushion  12  can be varied, the use of a semicrystalline polymer, such as polyurethane-PU or polyethylene-PE, is recommended. 
         [0037]    For all embodiments of the fluid systems disclosed above, the present invention envisions a transfer of fluid within or between fluid pockets. Another embodiment allows the membrane walls to deform permanently or to rupture and vent fluid into uncontained regions. These embodiments will result in single-use cushion devices. 
         [0038]    While the particular Anti-Blast and Shock Optimal Reduction Buffer as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.