Helmet

A helmet which is to be worn on a head of a wearer. The helmet includes a shell adapted to surround a wearer's head with the inner surface of the shell being spaced from the wearer's head at an initial pre-impact relative position. A subliner in contact with the wearer's head when the helmet is worn prior to an impact and during an impact, includes at least one viscoelastic foam subliner element extending from the inner surface of the shell. The subliner element is radially partitioned into individual and independent panel-shaped segments nested with respect to each other and have major side surfaces. Some of the nested segments have double-sided nano tape positioned between the major side surfaces thereof in direct contacting engagement with the nano tape and at least some of the major side surfaces of the remaining nested segments are in direct facing relation without nano tape therebetween.

BACKGROUND OF THE INVENTION

The present disclosure generally relates to a helmet whose purpose is to protect a wearer's head during a head impact. Extending radially outward from the wearer's head, the helmet may consist of one or multiple liner portions and one or multiple shell portions. Either way, there is typically a liner portion in contact with the wearer's head initially or during impact, that liner portion being herein defined as the subliner. The subliner may be comprised of individual subliner elements. The subliner is typically attached to an inner shell portion, the term inner having been added to unambiguously differentiate it from an outer shell portion in the case of a helmet with multiple shell portions. In helmets having just a single liner portion and a single shell portion, the liner portion would be the same as the subliner and the shell portion would be the same as the inner shell portion. In some helmets (typically hockey helmets) the inner shell portion may consist of individual shell segments. The subliner and inner shell portion together are herein defined as the helmet subliner system, and the present disclosure comprises an improved helmet subliner system, and an improved outer liner portion in the case of multiple shell helmets, to better protect the wearer from sustaining concussions and other head injuries.

Especially in multiple liner, multiple shell helmets, the subliner, as defined herein has been used primarily for obtaining the best fit and best comfort for the wearer. But as will be shown in this specification, the subliner, and more generally the subliner system may also be used to substantially improve the head protection performance of the helmet. The disclosure recognizes and takes advantage of the fact that all the forces that are applied to the wearer's head during a head impact are preferably applied through the subliner and its elements.

Recent postmortem brain investigations have found a high instance of chronic traumatic encephalopathy, or CTE, in the donated brains of deceased NFL football players, many of whom had suffered debilitating symptoms during their lifetimes, including unexplained rage, extreme mood swings, and substantial cognitive degeneration, all of which may have begun years after their football playing ended. Current research shows that CTE can almost always be traced back to long term repetitive head impacts which may include both concussive and sub-concussive impacts. It is believed those impacts would have been characterized by a high level of head angular acceleration, sometimes called rotational acceleration.

To reduce a wearer's head rotational acceleration, an effective helmet design may combine two strategies: one, absorb maximum impact energy to lower the impact force and acceleration, and two, redirect the now lowered force further down on the wearer's head to reduce head rotational acceleration.

In U.S. Pat. No. 11,547,166 B1, subliner elements attached to the inner surface of a surrounding shell are confined to a headband area of a user's head as part of the second strategy. As part of the first strategy, the subliner elements contain individual viscoelastic foam segments and double-sided nano tape in between the foam segments, whereby the foam segments absorb impact energy mostly from the rapid compression of the foam, and the nano tape in between the foam segments absorbs impact energy primarily from the rapid bending of the foam segments. Bending can occur when the shell end of a subliner element is displaced transversely with respect to the head end of the subliner element. The bending stretches the foam side surfaces on their convex side and shortens them on their concave side so that the nano tape in between adjacent bending foam segments becomes sheared across its thickness and absorbs energy as a result. However, for a subliner element located beneath a direct impact, the foam segments merely compress, and do not bend. Thus, in this case, less energy is absorbed by the element's nano tape.

This inherent shortcoming is overcome in the present disclosure by means of a new configuration of viscoelastic foam segments and nano tape. The disclosed new configuration results in increased bending of the viscoelastic foam segments, and thereby increased energy absorption by the nano tape in between, not just when the subliner element is directly compressed with no transverse motion between its shell end and head end, but also in cases when previously there would have been some bending. It thus results in more energy absorption by the nano tape portion of a subliner element, regardless of where the subliner element is located relative to an impact.

SUMMARY OF THE INVENTION

Briefly stated, the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The helmet includes a shell comprised of a hard impact resistant material having inner and outer surfaces. The shell is adapted to surround at least a portion of the cranial part of wearer's head with the inner surface of the shell being spaced from the wearer's head at an initial pre-impact relative position when the helmet is worn. A subliner, at least a part of which is adapted to be in contact with the wearer's head when the helmet is worn prior to an impact and during an impact, includes at least one subliner element extending from the inner surface of the shell. The at least one subliner element being constructed of an energy absorbing viscoelastic foam material. The at least one subliner element is radially partitioned into individual and independent panel-shaped segments nested with respect to each other and having major side surfaces. At least some of the nested segments have double-sided nano tape positioned between the major side surfaces thereof in direct contacting engagement with the nano tape and at least some of the major side surfaces of the remaining nested segments are in direct facing relation without nano tape therebetween.

In another aspect, the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The head has a pair of eyebrows, a pair of ears, and an annular headband shaped area encircling the wearer's head. The headband shaped area is approximately 0.75 to 1.25 inches wide and has a lower edge defining a plane positioned approximately 0.5 to 1.5 inches above the eyebrows and approximately 0.25 to 0.75 inches above an upper junction of the ears and the wearer's head. A top area centered about a top of the wearer's head encompassing approximately 0.44 to 7 square inches. A middle area of the head is defined between the headband area and the top area. The helmet includes a shell comprised of a hard impact resistant material. The shell has inner and outer surfaces and is adapted to surround at least a portion of the cranial part of wearer's head with the inner surface of the shell being spaced from the wearer's head at an initial pre-impact relative position when the helmet is worn. A subliner, at least a part of which is adapted to be in contact with the wearer's head when the helmet is worn prior to an impact and during an impact, includes a plurality of a first type of subliner elements extending from the inner surface of the shell at a location such that the first type of subliner elements are adapted to be aligned with the headband area when the helmet is worn. The first type of subliner elements is constructed of an energy absorbing viscoelastic foam material. The first type of subliner elements is radially partitioned into individual and independent panel-shaped segments nested with respect to each other and having major side surfaces. At least some of the nested segments have double-sided nano tape positioned between the major side surfaces thereof in direct contacting engagement with the nano tape and at least some of the major side surfaces of the remaining nested segments are in direct facing relation without nano tape therebetween. An apex type of subliner element extends from the inner surface of the shell at a location such that the apex type of subliner element is adapted to be aligned with the top area when the helmet is worn. The apex type of subliner element is comprised of an energy absorbing viscoelastic foam material and has a substantially flat lower surface which is substantially tangent to a surface of the wearer's head beneath it when the helmet is worn.

In another aspect, the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The head has a pair of eyebrows, a pair of ears, and an annular headband shaped area encircling the wearer's head. The headband shaped area is approximately 0.75 to 1.25 inches wide and has a lower edge defining a plane positioned approximately 0.5 to 1.5 inches above the eyebrows and approximately 0.25 to 0.75 inches above an upper junction of the ears and the wearer's head. A top area centered about a top of the wearer's head encompassing approximately 0.44 to 7 square inches. A middle area of the head is defined between the headband area and the top area. The helmet includes a shell comprised of a hard impact resistant material. The shell has inner and outer surfaces and is adapted to surround at least a portion of the cranial part of wearer's head with the inner surface of the shell being spaced from the wearer's head at an initial pre-impact relative position when the helmet is worn. A subliner, at least a part of which is adapted to be in contact with the wearer's head when the helmet is worn prior to an impact and during an impact, includes a plurality of a first type of subliner elements extending from the inner surface of the shell at a location such that the first type of subliner elements is adapted to be aligned with the headband area when the helmet is worn. The first type of subliner elements is constructed of an energy absorbing viscoelastic foam material and is radially partitioned into individual and independent panel-shaped segments nested with respect to each other. The panel-shaped segments have major side surfaces. At least some of the nested segments have double-sided nano tape positioned between the major side surfaces thereof in direct contacting engagement with the nano tape and at least some of the major side surfaces of the remaining nested segments are in direct facing relation without nano tape therebetween. An apex type of subliner element extends from the inner surface of the shell at a location such that the apex type of subliner element is adapted to be aligned with the top area when the helmet is worn. The apex type of subliner element is comprised of an energy absorbing viscoelastic foam material. The apex type of subliner element has a substantially flat lower surface which is substantially tangent to the surface of the wearer's head beneath it when the helmet is worn. An outer shell, comprised of a hard impact resistant material and having inner and outer surfaces, surrounds at least a portion of the inner shell. The inner surface of the outer shell being spaced from the outer surface of the inner shell at an initial pre-impact relative position. A plurality of outer liner elements are located in the space between the outer surface of the inner shell and the inner surface of the outer shell and are attached to both the outer surface of the inner shell and the inner surface of the outer shell. At least one of the outer liner elements is comprised of an energy absorbing viscoelastic foam and is radially partitioned into individual and independent panel-shaped segments nested with respect to each other. The panel-shaped segments have major side surfaces. At least some of the nested segments of the at least one outer liner element have double-sided nano tape positioned between the major side surfaces thereof in direct contacting engagement with the nano tape and at least some of the major side surfaces of the remaining nested segments of the at least one outer liner element are in direct facing relation without nano tape therebetween.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper” and “top” designate directions in the drawings to which reference is made. The words “inwardly,” “outwardly,” “upwardly” and “downwardly” refer to directions toward and away from, respectively, the geometric center of the helmet, and designated parts thereof, in accordance with the present disclosure. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import. The terms “angular acceleration” and “rotational acceleration” should be taken as synonymous from a force vector perspective. Similarly, the words “acceleration” and “deceleration” should also be taken as synonymous from a force vector perspective. It should also be understood that the terms “about,” “approximately,” “generally,” “substantially” and like terms, used herein when referring to a dimension or characteristic of a component of the disclosure, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that arc functionally similar. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit.

Referring now toFIGS.1,2and4, to best understand the configuration of the helmet subliner system or subliner10, which is a subject of this disclosure, it will be useful to first define certain areas of a potential wearer's head12which could come in contact with various types of subliner elements of the helmet14. In this regard, all the following will be defined: first area A, first plane Al, second plane B1, point b, second area B, and third area C.

FIG.1is a perspective side view of a wearer's head12having a pair of eyebrows26(only one is shown) and a pair of cars28(only one is shown). The head12includes a first area A, first plane Al, second plane B1, point b, second area B, and third area C. First area A is an annular headband shaped area encircling the wearer's head12. The first or headband shaped area A being approximately 0.75 to 1.25 inches wide, and preferably approximately 1.0 inch wide, and having a lower edge defining a plane positioned approximately 0.5 to 1.5 inches, and preferably approximately 1.0 inch, above the eyebrows26and approximately 0.25 to 0.75 inches, and preferably approximately 0.5 inches, above a location where the cars28join the wearer's head12at the top or, stated differently, an upper junction of the cars28and the wearer's head12. The first plane Al is a hypothetical plane defined by the lower edge of first area A. Picture second plane B1as a lower cover of an imaginary hard cover book being balanced horizontally atop the wearer's head12while the wearer's head12is maintained in an upright position, tilted neither right nor left, nor forward nor backward and where point b is approximately the center of the contact area between the lower cover of the imaginary book and the wearer's head12. Notice that first plane Al is tilted upward in the forward direction (the direction toward the face of the wearer) relative to second plane B. InFIG.1, the second plane B1is shown as transparent so that the contact area with the wearer's head12, point b, is apparent. The second or top area B is formed by a planar projection of an approximate 2-inch diameter circle (not shown) formed in the second plane B1centered about point b onto the wearer's head. That is, the second area B is generally circular and is centered about a top of the wearer's head12and extends 0.75 to 3 inches, and preferably 2 inches, in diameter in all lateral directions. As will be discussed, the second area B needn't be 2 inches in diameter, nor even circular. That is, the second area B can range from 0.44 to 7 square inches, or preferably 3.14 square inches. The third or middle area C is the area on the wearer's head12between first area A and second area B.

Referring again toFIGS.1,2and4and as will be described in detail in subsequent sections of the specification, subliner elements of a first type16are to be located in the first area A; subliner elements of a second type18are to be considered optional since they don't substantially contribute to the rotational acceleration reduction capability of the helmet, only to its comfort and fit, but when included they are to be utilized in third area C, and a subliner element of an apex type20is to be used in second area B. Each type of subliner element16,18,20has its own specific physical characteristics in accordance with the purpose of the disclosure which is to be able to reduce the level of head angular acceleration imparted to a wearer's head12during a head impact, regardless of the location or direction of the impact. Each of the subliner elements16,18,20is to be attached to an inner surface22of the inner shell24of the helmet14, preferably utilizing a commonly employed hook and loop type of fastener arrangement which allows for the simple assembly of, and changeout of, individual subliner elements16,18,20during a fitting process, with each subliner element16,18,20being positioned and sized in its thickness direction to best fit the size and shape of a wearer's head12. It will be appreciated by one skilled in the art, that other fastening elements could be used to releasably secure the subliner elements16,18,20to the inner surface22of the inner shell24of the helmet14, such as a releasable adhesive (not shown).

FIG.2is a perspective upper side view of a wearer's head12showing the first, second and apex types of subliner elements16,18,20as they would be located in their respective designated areas shown inFIG.1, in accordance with a first embodiment of the present disclosure. The individual subliner elements16,18,20are not attached to the wearer's head12(as could be falsely assumed fromFIG.2) but are merely illustrated in the figure where they would be located with respect to the wearer's head12when the helmet14is worn. Typically, they would be attached to the inner surface22of the inner shell24of the helmet14, as shown inFIG.4, preferably utilizing a commonly employed hook and loop type of fastener arrangement, described below. Alternatively, subliner elements18may be similarly attached to the side surface of subliner element20. The upper side viewpoint enables a fuller view of subliner element of the apex type20, which is preferably disc or oval shaped, oriented generally in the second plane B1, and is centered about point b at the top, or crown, of the head12. Subliner element of the apex type20has a flat (or nearly flat), horizontal (or nearly horizontal), lower surface20awhich may be either initially in contact with the wearer's head12or slightly spaced therefrom but may come into contact with the wearer's head12during an impact. Subliner element of the apex type20is shown here as a circular disc having a two-inch diameter to accommodate any misalignment of the center of the disc with the initial actual point of contact with a wearer's head12and to accommodate lateral displacements between the inner shell24and the wearer's head12during an impact. In general, the subliner element of the apex type20need not be circular, but it may be of any suitable contiguous shape typically having that approximate area or greater. The important thing is that its lower surface20abe of sufficient area to enable the accommodations described above, and that it be predominately flat and horizontal such that it is substantially tangent to the surface of the wearer's head12beneath it when the helmet14is worn.

To be able to appreciate why the lower surface20aof subliner element of the apex type20is preferred to be flat and horizontal, one may perform a simple experiment with one's own hand and one's own head. First, using one's hand, firmly cup the top of one's head. Then while still firmly cupping the head, forcefully move the cupping hand's forearm forward and backward, and side to side, and notice how the head is forced into violent motion likely involving significant head angular accelerations. Next, repeat the experiment while the hand is held flat and horizontal. The result: almost no forced motion of the head, and thus no head angular acceleration.

The subliner element of the apex type20, and also the subliner elements of the first type16, are preferably made of relatively stiff, very energy absorbent, viscoclastic foam material, capable of exhibiting a compressive stress of 20 psi for a static compression of 50% and at least 50 psi for a dynamic impact type compression of 50%, for example a vinyl nitrile foam such as IMPAX®, VN600, VN740, or VN1000 by Dertex Corporation, or a polyurethane foam such as LAST-A-FOAM®, FP 8015 by General Plastics Manufacturing Company. The subliner element of the apex type20should be thick enough not to compress all the way to its full densification condition under a peak normal impact force which could easily reach, and possibly even exceed, a thousand pounds. Although the weight of a full helmet would likely be substantially less than that (being typically under five pounds), if all the helmet weight were to be required to be supported by the subliner element of the apex type20, with its high dynamic stiffness designed to accommodate a dynamic force of over a thousand pounds, the supporting area around point b for a static force of just five pounds could be so small that the supporting pressure could be uncomfortably high for the wearer were it not for the subliner elements of the second type18, shown in third area C. This assumes the subliner elements16are not supporting much of the helmet weight. Alternatively, the subliner element of the apex type20, could be constructed as described in U.S. Pat. No. 11,641,904 which is hereby incorporated by reference in its entirety.

Optional subliner elements of the second type18, located in third area C, would preferably be made of a much more compliant material than that used for the subliner element of the apex type20, preferably at least five times more compliant and perhaps more than an order of magnitude more compliant than the stiffer materials recommended for subliner element of the apex type20. Such a material could be an extra soft polyurethane foam such as LAST-A-FOAM®, EF-4003 by General Plastics Manufacturing Company, or EZ-Dri foam by Crest Foam Industries, both having, a relatively flat static and dynamic compression stress vs. deflection characteristic (the former 2.6 psi at 10%, 2.7 psi at 20%, 2.8 psi at 30%, 3.0 psi at 40%, and 3.4 psi at 50% and the latter 0.3 psi at 10%, 0.35 psi at 20%, 0.4 psi at 30%, 0.45 psi at 40% and 0.55 psi at 50%), so when incorporating the proper total area to accomplish the function of supporting the full weight or nearly the full weight of the helmet with the latter material enabling about five times the support area for extreme comfort, the exact location and thickness of the subliner elements of the second type18would not be that critical for the subliner elements of the second type18to be able to successfully support all, or almost all, of the weight of the helmet, yet contribute very little side force to the wearer's head12during an impact. However, the second type of subliner elements18are preferably positioned generally equidistantly about and between the first and apex type of subliner elements16,20in the third area C.

FIG.2Ashows a second embodiment of the present disclosure wherein there is at least one of an alternative optional second type of subliner element18. That is, instead of a plurality of the second type of subliner elements18as shown inFIG.2, the second type of subliner elements18in accordance with the second embodiment are instead formed as a single annular ring18′. Using a single annular ring18′ has the advantage of easier assembly and greater simplicity. As with the first embodiment the ring type subliner element18′ may alternatively be attached to the side of subliner element20. Otherwise, all other elements of the subliner system10of the second embodiment are identical to the first embodiment.

FIG.1schematically shows the cervical spine13and its seven cervical vertebrae labeled Atlas (C1), Axis (C2), C3, C4, C5, C6 and C7. For both centered (directed toward the center of gravity of a wearer's head) and non-centered impacts having a large horizontal force component, almost all the side forces (and torques) that would be imparted to a wearer's head12during an impact would be imparted through the subliner elements of the first type16, which would be located, or substantially located, in first area A and generally evenly distributed/spaced thereabout. First area A places the point of application of these impact forces as close as possible to the head's two natural pivot points for angular acceleration: a lower pivot point12awhere the C7 cervical vertebrae (which can be located by the prominent bone at the base of the back of the neck) meets the T1 thoracic vertebrae, and an upper pivot point12bwhere the C1 cervical vertebrae (the atlas bone) meets the paired occipital condyle projections of the skull to enable forward and backward rotation (a “yes” motion) of the head and where the atlas bone meets the C2 cervical vertebrae (the axis bone) enabling axial rotation (a “no” motion) and side-to-side rotation of the head, this latter pivot being located approximately just above and slightly in front of the car lobes. Thus, all the head angular accelerating torques imparted to the user's head during an impact would be kept as small as possible for a given force as a result of this lowest practical positioning of subliner elements of the first type16.

As stated previously, the subliner element of the apex type20, due to its flat horizontal lower surface20a, typically does not impart a significant horizontal force to the wearer's head12. Yet, there may be certain impacts during which the lower surface of the subliner element of the apex type20would not remain flat but instead would tend to cup around the surface of the wearer's head12. One such type of impact is obvious: a direct downward impact to the crown, or top, of the helmet14, centered toward the center of gravity (e.g.) of the wearer's head12. Although that type of impact would result in cupping the lower surface of subliner element of the apex type20around the wearer's head12, little or no horizontal force would be imparted to the wearer's head12.

Another impact case that could cup the lower surface of the subliner element of the apex type20might be a downward impact to the top of the helmet at a point located away from the crown and generally directed toward the body of the wearer. Picture a running back diving over the goal line, his helmet getting struck in midair by the shoulder pad of a linebacker diving the other way to stop him. Here, in addition to a significant downward force through the subliner element of the apex type20(downward here meaning downward toward the body of the running back), there could be a not-insignificant horizontal force (horizontal here meaning horizontal relative to the body of the running back) imparted to the running back's head through the subliner element of the apex type20, as well as through the subliner elements of the first type16; for the most part the former would tend to rotate point b on the running back's head about the aforementioned upper pivot point toward the impact location, while the latter would tend to rotate point b about the aforementioned lower pivot point away from the impact location. So even in this case where the subliner element of the apex type20cannot avoid imparting a horizontal (sideways) force, the structure of the total subliner system10still tends to cancel the above two rotational head motions and thereby reduce the resultant angular acceleration of the wearer's head12.

Further reductions of imparted torque levels can be achieved by lowering the impact force levels, which can be accomplished by a proper choice of material for the subliner elements of the first type16, and by including specific structural features in the subliner elements of the first type16. Especially during an impact involving mostly a horizontal force component, only about one third of the subliner elements of the first type16(those located in the wide general region beneath the impact point) would be imparting most of the side normal force and side tangential force to the wearer's head12since the remaining subliner elements of the first type16would have tended to move away from the wearer's head12during the impact as the force-imparting subliner elements of the first type16compress and/or flex as a result of the high impact forces.

The force levels could be of the same order of magnitude as those potentially experienced by the subliner element of the apex type20(up to, and perhaps even more than a thousand pounds), and so the same energy absorbing viscoelastic foam materials cited for subliner element of the apex type20would be in order for subliner elements of the first type16, where their high energy absorption capability will help reduce the level of the high impact forces. The radial (thickness) dimension of the subliner elements of the first type16should be of sufficient length and have sufficient area to be able to avoid full densification at the maximum expected peak dynamic impact force, which could still be in the thousand-pound range for the total aggregate number of forces imparted on the subliner elements of the first type16. On average the radial thickness of the subliner elements of the first type16would be approximately 0.25 to 1.25 inches, and preferably 0.75 inches.

In a preferred embodiment, to increase lateral compliance to help further reduce the imparted tangential side forces, the subliner elements of the first type16may be partitioned into radially partitioned into individual and independent panel-shaped segments34nested with respect to each other and having major side surfaces36. More particularly, the panel-shaped segments34are generally flat and are generally rectangular or square shaped. The major side surfaces36are formed on both major sides of the panel-shaped segments34. The panel-shaped segments34include four minor side surfaces38between the major side surfaces36which are relatively thin compared to the major side surfaces36. In order to best achieve the goal of reduced imparted side forces, the major side surfaces36of the side-by-side panel-shaped segments34should be at least partially able to slide relative to each other in the segments' general radial direction. That is, at least some of the nested segments34have double-sided nano tape segments39positioned between the major side surfaces36thereof in direct contacting engagement with the nano tape39and at least some of the major side surfaces36of the remaining nested segments34are in direct facing relation without nano tape39therebetween. More particularly, it is preferred that the double-sided nano tape39be positioned between at least a majority of the facing major side surfaces36of the panel-shaped segments34except for two of the panel-shaped segments generally centrally positioned in the first subliner element16.

As shown inFIG.3, there are preferably a total of eight panel-shaped segments34, with the two innermost or central panel-shaped segments in direct contact without nano tape39therebetween. The remaining panel-shaped segments34have nano tape39positioned therebetween. Each panel-shaped segment34preferably extends between 10 mm to 50 mm in one planar direction, between 10 mm to 50 mm in the other planar direction, and the panel thickness is preferably between 1.5 mm and 7.5 mm. The number of panels that make up one subliner element is preferably, but not necessarily, an even number, such as four, six, eight, or ten, etc.FIG.3shows a case with eight panel-shaped segments. Double-sided nano tape segments preferably with a thickness between 0.5 mm to 2.5 mm, preferably substantially fill the major side surfaces36between adjacent viscoclastic foam panel segments34with one key exception, the exception being the area between the foam panel segments34at or near the middle of the stack. In a pre-impact condition, the interior major side surfaces36of the middle two foam panel segments34are located side-by-side without nano tape39filling the space between them. For example, with eight panel-shaped segments34, there would be only six nano tape segments39, not seven. Three of the nano tape segments39would be located between panel-shaped segments34numbered 1 and 2, 2 and 3, and 3 and 4, respectively, making up one half of the first type of subliner element16, and the other three nano tape segments39would be located between panel-shaped segments34numbered 5 and 6, 6 and 7, and 7 and 8, respectively, making up the other half of the first type of subliner element16. No nano tape segment is located between panels4and5.

It will be understood by those skilled in the art that nano tape39may be any nano tape which is commercially available. In general, nano tape39is an clastic tape that includes a nanofiber or nanotube structure which adheres to an adjacent surface due to molecular Van der Waals forces. In one embodiment, the nano tape39is comprised of carbon nanotube arrays provided on a backing layer formed of a flexible polymer, such as polyurethane, with Van der Waals interactions occurring between the carbon nanotube arrays and individual nanotubes and the adjacent surface. The nano tape is in the range of 0.5 to 2.0 mm thick and most preferably 1.0 mm thick.

While the preferred embodiment discloses eight panel-shaped segments34, the present disclosure is not so limited. Any number of panel-shaped segments34could be used depending on the size of the helmet and size of the user. Similarly, while it is preferred the two inner most panel-shaped segments34be in direct contact without nano-tape therebetween, additional panel-shaped segments34could also be in direct contact without nano-tape therebetween.

With continued reference toFIG.3, a mounting plate40is affixed to one end of the first type of subliner element16and extends generally perpendicular to the major side surfaces36of the panel-shaped segments34. The mounting plate40is positioned between the first type of subliner element16and the shell24. The minor side surfaces38of the panel-shaped segments34that face the inner shell24are permanently adhered to one side of the mounting plate40using a suitable flexible adhesive to form an assembled first type of subliner element16. This maintains the two nano tape assembled halves16a,16bof the first type of subliner element16in proper alignment at the free minor side surfaces38. The mounting plate40is preferably flexible and made of an clastic impact resistant polymer such as ABS having a thickness preferably between 0.25 mm to 1.0 mm.

A hook part30and a loop part32of a hook and loop fastener mechanism is used to secure the first type of subliner element16to the inner surface22of the inner shell24. The hook part30and loop part32are preferably of a type in common usage today for such applications. More specifically, the surface of the mounting plate40opposite the first type of subliner element16has one of a hook or loop portion of the hook and loop fastener mechanism secured thereto enabling the assembled first type of subliner element16to be removably affixed to the inner surface22of the inner shell24of the helmet to which the other of hook or loop portion of the hook and loop fastener system is adhered. The perimeter of mounting plate40preferably extends beyond the area of the adhered first type of subliner element16to maximize the ability of the hook and loop fastener mechanism to firmly hold the assembled first type of subliner element16in place during use, including during impacts. The end of the first type of subliner element16opposite the mounting plate40is referred to as the head end43.

Referring toFIGS.3A-3C, during an impact involving significant compression of the first type of subliner element16, the two subliner halves16a,16bare able to bulge away from each other, this bulging being accompanied by localized bending within each of the two subliner element halves16a,16b, primarily near their midpoint between the mounting plate40and the head end43.

The first type of subliner element16further includes an elastic element41surrounding at least a portion of the first type of subliner element16between the mounting plate40end and a head end43of the first type of subliner element16opposite the mounting plate40. The clastic element41preferably has a radial length which is at least 50% of a length of the panel-shaped segments34between the mounting plate40and the head end43of the first type of subliner element16opposite the mounting plate40.

The clastic element41is preferably in the form of a thin clastic sheet that surrounds the assembled first type of subliner16in a region between the mounting plate40and the head end43of the first type of subliner element16to hold the two first type of subliner halves16a,16btogether prior to an impact, and to return the subliner halves16a,16bto their pre-impact condition following an impact. The radial length of the clastic element41should preferably cover at least 25% to 75%, and preferably about 25%, of the distance between the mounting plate40and the head end43of the first type of subliner element16. The clastic element41should preferably have an elongation capability of at least fivefold because in the first type of subliner element's16pre-impact condition shown inFIG.3A, the clastic element41should be at least somewhat stretched to firmly hold the two subliner element halves16a,16btogether. During an impact, the clastic element41may need to stretch up to another threefold at its maximum stretch location approximately midway between the mounting plate40and the head end43. Natural rubber, or latex, has the property of being able to stretch at least sixfold, so latex may be at least one preferred material for the clastic element41.

FIG.3Ashows the exploded elements ofFIG.3assembled into a first type of subliner element16in an un-impacted state. The mounting plate40is shown at the bottom, and the line at the top represents the head end43in contact with the wearer's head.

FIG.3Bshows the first type of subliner element16shown inFIG.3Aas it is being compressed by a high-speed impact, represented by the arrows47, in which the level of compression has reached approximately 25%, which can typically occur in just 3 or 4 milliseconds. In this case, the two halves16a,16bof the first type of subliner element16have separated at the middle to form a central opening45and causing bending of the panel-shaped segments34as a result of that separation. The very rapid bending of the viscoelastic panel-shaped segments34causes a localized portion of the nano tape39surface in fixed contact with a localized convex portion of the major side surface36of panel-shaped segment34to rapidly elongate compared to the opposite surface of the nano tape39segment in fixed contact with a localized portion of the concave major side surface36of panel-shaped segment34which is rapidly shortening. This results in rapid shearing across the very thin thickness of the localized nano tape39and coupled with the high effective viscosity of the nano tape matrix material, this results in localized areas of significant nano tape energy absorption. There is also some energy absorption as a result of the compression of the viscoelastic panel-shaped segments34, at the top and bottom, and somewhat lesser energy absorption in the viscoclastic panel-shaped segment34as a result of the bending.

FIG.3Cshows the first type of subliner element16ofFIG.3Bafter an additional 5 milliseconds have passed when its compression has now reached more than 50%. In this case, the inner panel-shaped segments34now display more severe localized bending mid span, and how the outer panel-shaped segments34display less severe bending but over a more spread-out, less localized, area. This shows that the energy absorption from the nano tape39has continued at a similar level as before as a result of the more but less rapid bending, as indicated by the longer time span. The center opening45still exists and the folded-over viscoelastic panel-shaped segments34are now differently oriented and present a greater area for resisting additional compression. The over 50% compression point is where normally a straight compressing viscoclastic foam block would enter its densification region where the force would begin to go up exponentially with additional compression. Densification is the last stage of compression for a foam material where all the spaces are gone and only solid material remains to be compressed. But here, the center opening45, the reoriented panel-shaped segments34, and the greater compression area all combine to help avoid densification and its damaging higher forces and accelerations, including rotational accelerations. Along with the additional nano tape energy absorption, avoiding densification is another major advantage of the disclosed subliner configuration.

AlthoughFIGS.3B and3Cshow a straight compression situation, the first type of subliner element16deforms similarly under a combination of compression and shear, with the shear tending to alter the symmetrical nature of the deformation shown in the figures. However, there is still substantial energy absorption from both compression and bending of the viscoelastic panel-shaped segments34and substantial energy absorption in the nano tape39segments as a result of the bending of the panel-shaped segments34. In addition, all three conditions cited above for reducing the chance of densification still apply.

FIG.4is a cross-sectional side view located at the midsagittal plane of the wearer's head12showing the three types of subliner elements16,18,20as located inFIG.2and the inner shell24to which they are attached. The inner shell24may be part of a single liner, single shell helmet14as illustrated in the figure, or it may be part of a multiple liner, multiple shell helmet, as discussed in more detail below. The relative size of the inner shell24shown inFIG.4at the lower end of the indicated radial thickness range would be consistent with the former case if the helmet were for example an equestrian helmet or a ski helmet, and the relative size of the inner shell shown inFIG.4would also be consistent with the latter case if the helmet were for example a football helmet or a motorcycle helmet. A football helmet or a motorcycle helmet of the single liner, single shell type would typically have a larger subliner system10at the higher end of the indicated radial thickness range, which in that case would also be the outer shell. Thus, in a football helmet or motorcycle helmet of the single liner, single shell type embodiment, the radial spacing of the inner shell24from the head12would typically be greater than that shown inFIG.4and the subliner elements of the first, second and apex types16,18,20would accordingly have a greater radial dimension.

With continued reference toFIG.4, the inner surface22of the inner shell24above subliner element of the apex type20is shown to have a flat horizontal surface42rather than a concave surface. The inner shell24may be molded that way to achieve the flat horizontal surface42. The flat horizontal surface42is not absolutely necessary but it is preferred to enable the apex type of subliner element20to be flat on its upper surface as well as its lower surface20a, which helps to assure a horizontal lower surface20a, and makes it simpler and more controllable to determine, select, and properly align and apply a proper thickness subliner element of the apex type20so that it's lower surface20aremains horizontal and preferably barely touches the wearer's head12. As shown inFIG.4, the two cross-sectioned subliner elements of the second type18are shown in the third area C, properly radially compressed, as would be all of the other subliner elements of the second type18not shown in the cross-section, when all are supporting the full weight of the helmet, even though the full helmet with all its potential parts, including a potential face guard and a potential chin strap or jaw strap system, is not shown inFIG.4. Finally, the subliner elements of the first type16in the first area A each have a thickness to yield a snug but not uncomfortable fit with the wearer's head12.

FIG.5is a left side elevational view of the wearer's head12showing the inner shell24ofFIG.4located over the wearer's head12with all the subliner elements of the first, second and apex type16,18,20positioned as shown in phantom and as inFIG.2; all of the subliner elements of the first, second and apex type16,18,20being attached to the inner surface22of the inner shell24, typically by the easy-on, easy-off, hook and loop fastener mechanism30,32shown inFIG.3. The easy-on, easy-off capability helps in being able to customize the helmet for an individual wearer. The potential materials to be used for the inner shell24would depend upon which embodiment it is being used in. In the single liner, single shell helmet embodiment the inner shell24(which is now also the outer shell) must be able to handle a direct impact, so an impact resistant material such as polycarbonate or high impact ABS would be appropriate. In the multiple liner, multiple shell helmet embodiment described in more detail below, the inner shell24need not handle a direct impact, but it still would need to be able to handle high forces so a high strength polymer composite containing either glass fibers, carbon fibers, or KEVLAR® fibers (commonly understood as heat-resistant and strong synthetic fibers) or a composite utilizing a combination of different fibers could be appropriate. Also, for this embodiment, the inner shell24could be constructed of a thin metal, such as stainless steel or an aluminum alloy (either perforated, or not perforated), and in large quantities could be fabricated by pressing it to shape in a die with a large machine press. Such a thin metal shell, perhaps a thirty-second of an inch or less in thickness, could weigh even less than a comparable polymer composite shell.

FIG.6is a cross-sectional side view located at the midsagittal plane of a wearer's head12, showing a two liner, two shell, helmet14embodiment of the present disclosure.FIG.6shows the subliner system10ofFIG.4, plus a second or outer liner44and a second or outer shell46which together form an outer shell system48. Five outer liner elements50are shown in the second liner44because they cross the midsagittal plane. Typically, there may be ten to fifteen additional liner elements50in the second liner44which are not shown inFIG.6because they do not cross the midsagittal plane. That would add up to a likely total of fifteen to twenty total outer liner elements50in the second liner44, spread out more or less equidistantly throughout the available space between the inner shell24and the second or outer shell46.

All the outer liner elements50of the second liner44are firmly attached to both the outer surface of the inner shell24and the inner surface of the outer shell46. By contrast, subliner elements of the first, second and apex types,16,18,20in the subliner system10can only be attached to the inner shell24(they cannot be attached to a wearer's head). The firm attachment of the outer liner elements50of the second liner44to both the inner and outer shells24,46enables the outer liner elements50to experience not just high compression forces, but high shear forces and high tensile forces as well. As a result, the attachment requirement here is beyond the capability of a standard hook and loop fastener and is more in the realm of a high strength, wide temperature range, flexible adhesive, such as LOCTITE® 4902, or LOCTITE® Plastic Bonder, both by Henkel Corporation. The former is a one-part adhesive, the latter a two-part adhesive, and both are quick curing.

These flexible, high strength attachments make it possible for all the outer liner elements50of the second liner44to participate in mitigating any impact to the wearer's head12, regardless of the impact's location or direction. That mitigation is accomplished through the widespread positioning of the outer liner elements50and their ability to efficiently absorb energy in three different modes: compression, shear, and tension. For example, for any centered impact the outer liner elements50of the second liner44generally located in the region beneath the impact will experience compression, those located to the side of the impact will experience shear, and those located opposite the impact will experience tension, while those located in between will experience some combination of compression, shear, and tension. For any non-centered impact most of the outer liner elements50of the second liner44will experience a higher degree of shear. Because every impact is different in its location and direction, each outer liner element50in the second liner44must be able to absorb energy at all the expected possible levels of compression, shear, and tension, and combinations thereof.

Furthermore, in order to even be in a position of optimally absorbing energy, each outer liner element50of the second liner44must become deformed during an impact to its full extent by the outer shell46, not just those outer liner elements50beneath the impact, but those to the side of the impact, and those opposite the impact as well, and the outer shell46must remain rigid enough during the impact to be able to accomplish that. Because the outer shell46is relatively thin and typically made of a polycarbonate or high impact ABS, this may require that the outer shell46be rigidized, especially near its opening to accommodate a wearer's head12, which is the place where it is the weakest. Notice in the figure, that there are two molded-in internal rings52near the opening to accomplish the rigidizing, but other rigidizing approaches such as severe contouring or metal banding (not shown) would also be acceptable.

Achieving the optimum energy absorption by all the outer liner elements50of the second liner44also requires they be fabricated of a material having an inherent high energy absorbing capability, and that the material also have a proper level of dynamic stiffness for the total outer liner element50footprint area. To meet these criteria, the outer liner elements50of the second liner44may be fabricated from the same list of materials recommended for subliner elements of the first and apex types16,20, the list including: a vinyl nitrile foam such as IMPAX® VN600, VN740, or VN1000 by Dertex Corporation, or a polyurethane foam such as LAST-A-FOAM® FP 8015 by General Plastics Manufacturing Company. However, in block form, each material likely presents too much dynamic stiffness in shear as compared to its dynamic stiffness in compression and tension. So to reduce an outer liner element's dynamic stiffness in shear, without at the same time reducing its dynamic stiffness in compression or tension, partitioning of each outer liner element50into discrete adjacent segments is preferred, similar to what has been previously discussed for the first type of subliner elements16, panel-shaped segments34with nano tape39segments located therebetween, except there is no nano tape39segment between the middle two panel-shaped segments34. The outer liner elements50located around the periphery of the helmet, in their pre-impact, installed condition should be preferably partially compressed, approximately 25% as shown inFIG.3B, in order to be able to experience a sudden change in bonding during an impact, not only in compression, but also in tension as when the impact occurs opposite their location. That way the nano tape39is able to absorb energy when otherwise it would not. This is feasible for the oppositely located, peripheral outer liner elements50abecause the pre-impact forces they exert on the two shells cancel out. No such cancellation is possible for the outer liner elements50bwhich are not located on the periphery. There is no opposite second liner element for these and they would be installed in an un-compressed condition as shown inFIG.3A. There is no loss of function in doing so, as these inner outer liner elements50bare not likely to experience tension during an impact.

FIG.7illustrates a left side elevational view showing the outer shell46ofFIG.6positioned on a wearer's head12. The size and shape of the outer shell46might be typical of a football helmet.

FIG.8is a left side elevational view of a wearer's head12showing a face guard102attached to the outer shell46ofFIG.8, and a chin strap104positioned on the wearer's chin and attached to the inner shell24ofFIG.5, both typical of a football helmet application.

Finally, although only a first preferred embodiment having a subliner system10, and a second preferred embodiment having a subliner system10and an outer shell system48have been described in significant detail, the addition of a third liner and a third shell (not shown) would still be within the scope of the present disclosure. It will also be appreciated by those skilled in the art that changes, or modifications could be made to the above-described embodiments without departing from the broad inventive concepts of the disclosure. Therefore, it should be appreciated that the present disclosure is not limited to the particular use or particular embodiments disclosed but is intended to cover all uses and all embodiments within the scope or spirit of the described disclosure.