Abstract:
A protective helmet which employs an inner shell, an outer shell, and dampeners positioned between the inner and outer shells which facilitate rotational movement between the inner and outer shells. The dampeners also provide shock absorption to counter the rotational acceleration caused by an impact to the helmet.

Description:
FIELD OF INVENTION 
     The present invention relates to personal safety equipment for use by athletes, military personnel, motor sports participants and the like and in particular, protective headgear adapted to minimize rotational acceleration and/or axial compressive forces incident on the head of a wearer. 
     BACKGROUND 
     There are many professions and activities in which participants may be exposed to physical contact which may result in head injury. For example, athletes participating in contact sports, such as American football, are subject to exposure to concussions, hyperextension, whiplash-type head movement, and cervical compressive forces. Football players at positions such as interior lineman, for example, are subjected to physical contact on virtually every play which can force the player&#39;s head rapidly backward, to create a whiplash effect which can result in serious and disabling injury. Additionally, it has recently been noted that glancing blows, or hits not directly on center, lead to concussions as well as torsional neck injury. Moreover, persons involved in activities such as high speed vehicle test piloting and race car driving can also be exposed to hyperextension or whiplash-type injuries caused by high rates of acceleration and impact forces. Military personnel are likewise exposed to combat and training situations which place them at risk of head injury. For participants in these and other activities, protective headgear such as helmets is often standard equipment. 
     Most blows to the head of participants in such activities are not direct, on-axis impacts, which cause linear acceleration. Generally, the blows to the head are glancing blows, with the head of a participant twisting as a result. Recent studies have shown that concussions are likely most often caused by rotational acceleration of the head, i.e., combined linear and angular acceleration. 
     Currently, the solution to prevent or minimize these injuries has simply been to add more padding to existing helmets. Some designs have added “crumple zones” to the exterior of the helmet, or a padded cap. These existing designs do not prevent or minimize the effects of glancing or off-center impacts which result in rotational acceleration. 
     SUMMARY OF INVENTION 
     There is a need for protective headgear which may reduce the likelihood of certain head and neck injuries, such as concussion, whiplash, and hyperextension of the neck. The presently disclosed subject matter provide a helmet which offers improved protection against head and neck injury as a consequence of rotational acceleration upon impact. 
     In one aspect the presently disclosed subject matter relates to a protective helmet which employs an inner shell, an outer shell, and dampening elements positioned between the inner and outer shells which facilitate rotational movement between the inner and outer shells. The dampening elements, also referred to herein as dampeners, also provide shock absorption to counter the rotational acceleration caused by an impact to the helmet. 
     The inner shell includes an exterior surface and an interior surface which faces the head of a wearer. The exterior surface of the inner shell includes one or more dampeners that are formed and operable to interact with complementary dampeners included on the interior surface of the outer shell. In one embodiment, the complementary dampeners comprise essentially corresponding male dampener and female dampener elements. One skilled in the art will recognize that the male dampener element(s) may be disposed on either the inner shell outer surface or outer shell inner surface, and the corresponding female dampener element(s) may likewise be so disposed, as long as the male and female elements are disposed such that they are formed, situated and operable to interact with each other. Moreover, one or more male and female dampeners may be disposed on the same surface, as long as a counterpart female and male dampener is disposed on the opposite surface. 
     In one embodiment the inner shell may further include padding on its interior surface to cushion the wearer&#39;s head from direct blows and/or provide a comfortable and secure fit. Examples of such padding may include pads which are employed inside conventional, commercially-available helmets. The padding may be removable. 
     The dampeners may be any shape adequate to enable translational and rotational movement between the respective male and female dampeners. In one embodiment the female dampeners include a generally round opening formed therein for receiving the male dampener, which is generally cylindrical and sized to fit within the opening formed in the female dampener. The outer perimeter of the female dampener may have any suitable shape. When the inner shell is fitted in the outer shell, the male dampeners are situated in the opening of the female dampener. The male dampener is thus able to move translationally, as well as rotatably, within the female dampener. 
     The dampeners can be made from a variety of materials, such as elastic polymers, viscoelastic gels, magnetic material, etc. The dampeners can also be a combination of these materials. In further embodiments the dampeners may further include biasing elements such as springs, magnets, etc. 
     In some embodiments, there may be space between the outer perimeter of the male dampener and the inner perimeter of the female dampener. 
     In an embodiment in which the dampeners are polymers or gels, the dampeners may be in contact with each other along the perimeter of the male dampener and corresponding interior surface of the female dampener. In this embodiment the dampeners are operable to compress and elongate upon impact, permitting rotational and translational movement. 
     In embodiments employing magnetic dampeners, the male dampener may be a magnetic material and the female dampener may be a magnetic material having similar polarity, creating an opposing magnetic force, and a dampening effect. 
     The complementary male and female dampeners may include one or more biasing elements disposed between male and female dampeners. Those having skill in the art will recognize that the male and female dampeners may be engaged such that there is a gap formed between the outer perimeter of the male dampener and the inner perimeter of the female dampener. A biasing element may be disposed in the gap without being connected to either the male or female dampener; may be connected to one or the other of the dampeners; or be connected to both male and female dampeners. For example a spring may be anchored at each end to corresponding male and female dampeners. In another embodiment a biasing element such as a spring may be positioned in a gap between corresponding male and female dampeners but connected to only one, or neither, of the corresponding dampeners. Magnetic materials having substantially the same polarity may be disposed in, on or around corresponding, complementary dampeners creating an opposing magnetic force, and a biasing effect between the corresponding, complementary dampeners. 
     Furthermore, in embodiments in which there is no space between the perimeters of complementary dampeners, biasing elements may also be included. For example, a biasing element such as a spring may be disposed on the perimeter of one or both of the complementary, corresponding dampeners. Likewise, magnetic materials having substantially the same polarity may be disposed in, on or around corresponding, complementary dampeners creating an opposing magnetic force, and a biasing effect between the corresponding, complementary dampeners. 
     The inner and outer shells may be removably fitted together. Although in some embodiments the only connection between the inner and outer shell may be formed as a result of the male and female dampeners being in contact, the inner and outer shells may be further connected to each other so as to secure the inner shell to the outer shell while permitting rotational and translational movement upon impact. For example, complementary hook and loop fasteners, snaps, magnets etc. may be employed in regions of the shells such as along portions of the perimeter of the inner and outer shells. In other embodiments, the inner and outer shells may be engaged in close contact with each other via force-fit or the like. 
     When the outer surface of the outer shell of a helmet employing the disclosed subject matter sustains an impact force, the force of the impact causes the outer shell to move. The dampeners between the inner and outer shells absorb this energy, thereby reducing the amount of rotational acceleration transmitted to the inner shell. This energy may be further reduced by padding on the interior of the inner shell, thereby minimizing the amount of force transmitted to the wearer&#39;s head. After the impact has been absorbed, the dampeners return to their stable state, or rest position, thus realigning the inner and outer shells. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purposes of illustration, there are forms shown in the drawings that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a front perspective view of a helmet in accordance with an embodiment of the present disclosure; 
         FIG. 2  is an elevated side perspective view of an inner shell of a helmet in accordance with an embodiment of the present disclosure; 
         FIG. 3  is a bottom perspective view of an outer shell of a helmet in accordance with an embodiment of the present disclosure; 
         FIG. 4  is a cross-sectional view of the helmet according to  FIG. 1  taken through line A-A′; 
         FIG. 5  is a cross-sectional view of the helmet according to  FIG. 1  taken through line B-B′; 
         FIG. 6  is an elevated rear perspective view of a helmet in accordance with an embodiment of the present disclosure, in which dampeners and an inner shell are shown in phantom and the dampeners are depicted in a rest state; 
         FIG. 7  is an elevated rear perspective view of a helmet in accordance with an embodiment of the present disclosure, in which dampeners and an inner shell are shown in phantom and the dampeners are depicted in a shifted state, demonstrating movement of the outer shell in relation to the inner shell; 
         FIG. 8  is a bottom perspective view of an outer shell of a helmet in accordance with an embodiment of the present disclosure; 
         FIG. 9  is an elevated rear perspective view of a helmet in accordance with an embodiment of the present disclosure, in which dampeners and an inner shell are shown in phantom and the dampeners are depicted in a rest state; 
         FIG. 10  is a cross-sectional view of the helmet according to  FIG. 9  taken through line C-C′; 
         FIG. 11  is a cross-sectional view of the helmet according to  FIG. 9  taken through line D-D′; 
         FIG. 12  is an elevated rear perspective view of a helmet in accordance with an embodiment of the present disclosure, in which dampeners and an inner shell are shown in phantom and the dampeners are depicted in a shifted state, demonstrating movement of the outer shell in relation to the inner shell; 
         FIG. 13  is a cross-sectional view of an alternative embodiment of the helmet according to  FIG. 1  taken through line A-A′; 
         FIG. 14  is a cross-sectional view of an alternative embodiment of the helmet according to  FIG. 1  taken through line A-A′; and 
         FIG. 15  is a cross-sectional view of an alternative embodiment of the helmet according to  FIG. 1  taken through line A-A′. 
     
    
    
     DETAILED DESCRIPTION 
     The following is a detailed description of the invention provided to aid those skilled in the art in practicing the present invention. Those of ordinary skill in the art may make modifications and variations in the embodiments described herein without departing from the spirit or scope of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for describing particular embodiments only and is not intended to be limiting of the invention. All publications, patent applications, patents, figures and other references mentioned herein are expressly incorporated by reference in their entirety. 
     With reference to the drawings, wherein like numerals indicate like elements, there is shown in  FIG. 1  a helmet  10  having an outer shell  20  and an inner shell  30 . Helmet  10  may further include a facemask  50  and one or more pads  60  attached to the interior surface of the inner shell  30 . 
     Outer shell  20  may be formed of any suitable material such as polycarbonate, carbon fiber, poly-paraphenylene terephthalamide (including KEVLAR® aramid fiber from DuPont), padded leather or synthetic material, etc. Inner shell may be formed of any suitable material such as polycarbonate, carbon fiber, poly-paraphenylene terephthalamide (including KEVLAR® aramid fiber from DuPont), leather, cloth, rubber, etc. 
     Pads  60  may be employed on the interior surface of inner shell  30  to cushion the wearer&#39;s head from direct blows and/or provide a comfortable and secure fit. Examples of suitable pads  60  include pads which are employed inside conventional, commercially-available helmets. Examples of suitable pad materials include plastic, foam, viscoelastic polymer, rubber, silicone, gel filled pads, air-filled or air fillable pads, etc. The pads  60  can be permanently attached or removable as is known in the art. Likewise, the pads  60  can be a singular pad system, or a system of pads manufactured from various different materials known in the art. 
     As will be recognized by those having ordinary skill in the art, facemask  50  may be any type of facemask suitable for the helmet  10 . Facemask  50  is preferably attached to at least the outer shell  20  of helmet  10 . Facemask  50  may be removable. 
     With further reference to  FIGS. 2 and 3 , in accordance with one embodiment, inner shell  30  includes female dampeners  32  arrayed on an exterior surface thereof and outer shell  20  includes male dampeners  22  arrayed on an interior surface thereof. In another embodiment, one or more female dampeners  32  may be arrayed on the interior surface of outer shell  20 , and one or more male dampeners  22  may be arrayed on the exterior surface of the inner shell  30 . 
     Now referring to  FIGS. 4-6 , when the inner shell  30  is fitted in the outer shell  20 , the male dampeners  22  are situated in an opening  34  formed in the female dampener  32 . The male dampener  22  is thus able to move translationally, as well as rotatably, within the female dampener  32 . The male dampeners  22  are formed and operable to interact with complementary female dampeners  32 . Regardless of the shell ( 20  or  30 ) on which the dampeners  22 ,  32  are located, the male dampeners  22  and female dampeners  32  are disposed such that they are formed, situated and operable to interact with a corresponding, complementary dampener. It will be apparent to those skilled in the art that one or more male  22  and female  32  dampeners may be disposed on the same surface, as long as a counterpart female dampener  32  or male dampener  22  is disposed on the opposite surface. 
     While the female dampeners  32  are depicted as cylindrical elements having a round opening  34  formed therein, and the male dampeners  22  are depicted as generally cylindrical, the dampeners  22 ,  32  may be any shape adequate to enable translational and rotational movement between the respective male  22  and female  32  dampeners. As can be seen in  FIGS. 4-6 , the size of the male dampeners  22  relative to the female dampeners  32  is such that there is space between the outer perimeter of the male dampener  22  and the interior perimeter of the opening  34  of the female dampener  32  for accommodating rotational and translational movement therebetween, regardless of the perimeter shape of the male dampener  22  and/or the opening  34  of the female dampener  32 . Accordingly, male dampener  22  may have any exterior perimeter shape, such as cylindrical, square, triangular, star, etc. The outer perimeter of the female dampener  32  may have any suitable shape. The perimeter of the opening  34  of the female dampener  32  may be any shape suitable to accommodating rotational and translational movement between the dampeners  22  and  32 . In one embodiment the female dampener  32  includes a generally round opening  34  formed therein for receiving the male dampener  22 . 
     The dampeners  22 ,  32  can be made of a variety of materials such as elastic polymers, viscoelastic gels, air-filled or air fillable structures, rubber, silicone, magnets, coils, etc. The dampeners  22 ,  32  can also be formed of a combination of these materials. 
     In some embodiments, for example in cases in which either or both of the dampeners  22 ,  32  are polymers or gels, the dampeners  22 ,  32  may be in full or partial contact with each other along the perimeter of the male dampener  22  and corresponding interior perimeter surface of the opening  34  of female dampener  32 . In this embodiment the dampeners  22 ,  32  are operable to compress and elongate upon impact, permitting rotational and translational movement of the shells  20  and  30 . 
     In some embodiments there may be space between the outside perimeter of the male dampener  32  and the inner perimeter surface of the female dampener. 
     When the outer surface of the outer shell  20  of a helmet  10  employing the disclosed subject matter sustains an impact force, the force of the impact causes the outer shell  20  to move. The dampeners  22 ,  32  between the inner shell  30  and outer shell  20  absorb this energy, thereby reducing the amount of rotational acceleration transmitted to the inner shell  30 . This energy may be further reduced by padding 60 on the interior of the inner shell  30 , thereby minimizing the amount of force transmitted to the wearer&#39;s head. After the impact has been absorbed, the dampeners  22 ,  32  return to their stable state, or rest position, thus realigning the inner and outer shells. 
     With reference to  FIG. 6 , in accordance with one embodiment the outer shell  20  of helmet  10  is in its neutral, or rest, position in relation to the inner shell  30 . The male dampeners  22  are substantially centered within the openings  34  of female dampeners  32 . With further reference to  FIG. 7 , the outer shell  20  is shown in an absorption position in relation to the inner shell  30 . The male dampeners  22  are not centered within the openings  34  of female dampeners  32 . After impact, the dampeners  22 ,  32  work against each other to return the outer shell  20  to this neutral, or rest, position in relation to the inner shell  30 . Impact forces are distributed on the sides of the complementary dampeners  22 ,  32 . These forces are operable to return the dampeners  22 ,  32  to the rest position, and thereby the outer shell  20  is restored to the rest position. Furthermore, because the dampeners  22 ,  32  can absorb energy in all directions, axially, laterally, or rotationally, they can protect the wearer from a hit from any direction. 
     Now referring to  FIGS. 8-11 , in further embodiments, helmet  10  may include biasing elements  40 . One skilled in the art will recognize biasing elements may be employed to maintain dampeners  22 ,  32  in a predetermined position, referred to herein as a rest or stable position, to restore dampeners  22 ,  32  to a rest position after movement due to impact, and/or control the velocity with which relative movement between the dampeners  22 ,  32  and shells  20  and  30  occurs. Examples of biasing elements  40  include coil springs, magnets, elastic bands, etc. The skilled artisan will recognize that the choice of biasing element  40  and the characteristics thereof will depend on the amount of elongation, deflection and restoring force desired for a particular application. 
     With reference to  FIG. 8 , biasing elements  40  may be positioned adjacent male dampener  22 . 
     Now referring to  FIGS. 9-11 , in one embodiment biasing elements  40  are positioned between a male dampener  22  outer perimeter and female dampener  32  opening  34  interior perimeter. 
     In embodiments in which there is no space between the outside perimeter of the male dampener  22  and inside perimeter of the opening  34  of the female dampener  32 , biasing elements  40  may also be included. 
     In embodiments employing magnetic dampeners  22 ,  32 , the male dampener  22  may be a magnetic material and the female dampener  32  may be a magnetic material having similar polarity, creating an opposing magnetic force, and a dampening effect. In cases in which the dampeners  22 ,  32  are non-magnetic, magnetic biasing elements  40  may be employed in a similar fashion. 
     With reference to  FIGS. 9-11 , the outer shell  20  is in its neutral position in relation to the inner shell  30 . Male dampeners  22  are centered within openings  34  of female dampeners  32 . As shown in  FIG. 9 , in one embodiment the biasing elements  40  disposed between the male dampeners  22  and female dampeners  32  are springs in a rest position and may be in substantially the same compression state. With reference to  FIG. 12 , the outer shell  20  is in an absorption position in relation to the inner shell  30 , resulting in the biasing elements being energized. The male dampeners  22  are not centered within the openings of female dampeners  32 . After each impact, the biasing elements  40  are energized and work against each other to restore the outer shell  20  to the rest position in relation to the inner shell  30 . The arrangement of plural springs positioned between the dampeners  22 ,  32  provides forces which restore the dampeners  22 ,  32 , and thereby the outer shell  20  to the rest position. 
     As noted, the outer and inner shells  20 ,  30  may be removably fitted together. Although in some embodiments the only connection between the outer shell  20  and inner shell  30  may be formed as a result of the male and female dampeners  22 ,  32  being in contact with each other, or as a result of biasing elements  40  connecting the dampeners  22 ,  32 , the outer and inner shells  20 ,  30  may be further connected to each other so as to secure the inner shell  30  to the outer shell  20  while permitting rotational and translational movement upon impact. For example, complementary snaps, magnets etc. may be employed in regions of the shells such as along portions of the perimeter of the outer and inner shells  20 ,  30 . Now referring to  FIG. 13 , two embodiments of connectors are shown. In one aspect, magnets  80  and  82 , having opposing polarity, are attached, respectively, to outer shell  20  and inner shell  30  and positioned so that they will connect when brought into close proximity with each other. One skilled in the art will recognize the magnets  80  and  82  (as well as other connectors) may be positioned in various locations in the helmet  10  to achieve the desired result. In another aspect, a web  84  is fixed at each opposing side, respectively, to outer shell  20  and inner shell  30 . Web  84  may be any suitable material including fabric and/or polymer, or a block of foam or other suitable material. Now referring to  FIG. 14 , in one embodiment male dampener  22  may include an opening or recess  24  formed therein. A tether  86  may be permanently or removably fixed at one end to a region within an opening  34  in female dampener  32  and fixed at another end to an opening  24  formed in male dampener  22 . The tether  86  may be formed of any suitable material well-known to those having ordinary skill in the art. For example, the tether  86  may be formed of a hook and loop fastener (including VELCRO® fastening material available from VELCRO USA® of Manchester, N.H.), whereby a strip of hook material extends from one shell surface and a strip of loop material extends from an opposing shell surface, the strips being located within the dampeners  22 ,  32  or outside the dampeners. In this manner the inner and outer shells  22 ,  32  may be removably fixed to each other. The tether  86  may also be permanently or removably fixed at each end to opposing shell surfaces outside the dampeners. In other embodiments, the outer and inner shells  20 ,  30  may be engaged in close contact with each other via force-fit or the like. 
     Now referring to  FIG. 15 , in another embodiment male dampener  22  includes a rim  26  which is operable to engage a groove  36  formed in female dampener  32 . The engagement of rim  26  and groove  36  permit rotational and translational movement between the inner and outer shells  22  and  32 . 
     Although the systems and apparatus of the present disclosure have been described with reference to exemplary embodiments thereof, the present disclosure is not limited thereby. Indeed, the exemplary embodiments are implementations of the disclosed systems and methods are provided for illustrative and non-limitative purposes. Changes, modifications, enhancements and/or refinements to the disclosed systems and apparatus may be made without departing from the spirit or scope of the present disclosure. Accordingly, such changes, modifications, enhancements and/or refinements are encompassed within the scope of the present invention.