U.S. patent application number 14/115701 was filed with the patent office on 2014-04-03 for systems and methods for attenuating rotational acceleration of the head.
The applicant listed for this patent is Lioyd Cooper, James Michael Johnston, Uday Vaidya. Invention is credited to Lioyd Cooper, James Michael Johnston, Uday Vaidya.
Application Number | 20140090155 14/115701 |
Document ID | / |
Family ID | 47108257 |
Filed Date | 2014-04-03 |
United States Patent
Application |
20140090155 |
Kind Code |
A1 |
Johnston; James Michael ; et
al. |
April 3, 2014 |
SYSTEMS AND METHODS FOR ATTENUATING ROTATIONAL ACCELERATION OF THE
HEAD
Abstract
In one embodiment, a system for attenuating rotation
acceleration of the head includes a protective helmet adapted to be
worn on the head of a user, the helmet including an outer shell
having an inner surface, an inner liner provided within the shell,
the liner comprising one or more pads, and means for enabling the
shell to rotate relative to the user's head, the means excluding
cell-based foam.
Inventors: |
Johnston; James Michael;
(Birmingham, AL) ; Cooper; Lioyd; (Birmingham,
AL) ; Vaidya; Uday; (Birmingham, AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Johnston; James Michael
Cooper; Lioyd
Vaidya; Uday |
Birmingham
Birmingham
Birmingham |
AL
AL
AL |
US
US
US |
|
|
Family ID: |
47108257 |
Appl. No.: |
14/115701 |
Filed: |
May 4, 2012 |
PCT Filed: |
May 4, 2012 |
PCT NO: |
PCT/US2012/036577 |
371 Date: |
December 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61482967 |
May 5, 2011 |
|
|
|
Current U.S.
Class: |
2/414 |
Current CPC
Class: |
A63B 71/10 20130101;
A42B 3/064 20130101; A42B 3/125 20130101; A42B 3/127 20130101 |
Class at
Publication: |
2/414 |
International
Class: |
A42B 3/12 20060101
A42B003/12; A63B 71/10 20060101 A63B071/10 |
Claims
1. A protective helmet adapted to be worn on the head of a user,
the helmet comprising: an outer shell having an inner surface; an
inner liner provided within the shell, the liner comprising one or
more pads; and means for enabling the shell to rotate relative to
the user's head, the means excluding cell-based foam.
2. The helmet of claim 1, wherein the shell is made of an
acrylonitrile butadiene styrene or polycarbonate alloy
material.
3. The helmet of claim 1, wherein the means for enabling the shell
to rotate comprise means for enabling at least one pad to slide
within and relative to the shell.
4. The helmet of claim 3, wherein the means for enabling the at
least one pad to slide comprise a raceway formed on the inner
surface of the shell along which the at least one pad can
slide.
5. The helmet of claim 4, wherein the raceway is defined by first
and second ribs that confine the at least one pad to the
raceway.
6. The helmet of claim 5, wherein one or both of the raceway and
the at least one pad is provided with a low-friction material that
facilitates sliding of the at least one pad relative to the
raceway.
7. The helmet of claim 4, wherein the raceway is horizontally
aligned within the shell so that the at least one pad can laterally
slide from the front of the shell toward the back of the shell and
vice versa.
8. The helmet of claim 3, wherein the means for enabling the at
least one pad to slide comprise a rail that guides the at least one
pad.
9. The helmet of claim 8, wherein the rail is provided on the inner
surface of the shell and the at least one pad comprises a groove
adapted to receive the rail.
10. The helmet of claim 8, wherein the rail is provided on an outer
surface of the at least one pad and the shell comprises a groove
adapted to receive the rail.
11. The helmet of claim 3, wherein the means for enabling the at
least one pad to slide comprise an isolation bushing including at
least one compression spring.
12. The helmet of claim 3, further comprising means for slowing the
rotation of the shell and dissipating rotational force that caused
the rotation.
13. The helmet of claim 12, wherein the means for slowing comprise
a force dissipation pad that is securely affixed to the inner
surface of the shell and that is adapted to abut the at least one
pad once it has slid a predetermined distance relative to the
shell.
14. The helmet of claim 13, wherein the force dissipation pad
comprises a compression region that is adapted to compress to
dissipate the rotational force.
15. The helmet of claim 14, wherein the compression region
comprises vertical grooves formed in a lateral edge of the force
dissipation pad.
16. The helmet of claim 14, wherein the force dissipation pad is a
rear pad attached to a rear of the shell and wherein the at least
one pad comprises a lateral pad positioned on a lateral side of the
shell.
17. The helmet of claim 16, wherein the lateral pad comprises
vertical ribs that easily yield to horizontal shear forces to
further dissipate the rotational force.
18. The helmet of claim 12, wherein the means for slowing comprise
at least one compression spring provided within the shell.
19. The helmet of claim 1, wherein the means for enabling the shell
to rotate comprise at least one pad that includes a
three-dimensional spacer fabric comprising spaced layers of
material that are connected by fibers that extend between the
layers in a direction generally perpendicular to the layers, the
fibers being adapted to absorb lateral and rotational shear
forces.
20. The helmet of claim 19, wherein the three-dimensional spacer
fabric is impregnated with a cured resin that provides rigidity to
the fabric.
21. The helmet of claim 20, wherein the resin comprises one or more
of thermoplastic polyurethane, poly caprolactum (nylon), or epoxy
resin.
22. The helmet of claim 19, wherein the spaced layers are woven
layers of material.
23. The helmet of claim 22, wherein the woven layers are weaves of
glass or polymeric fibers or yarns.
24. The helmet of claim 19, wherein the fibers that extend between
the layers are glass or polymer fibers.
25. The helmet of claim 19, wherein the fibers that extend between
the layers are curved.
26. The helmet of claim 19, wherein the at least one pad further
comprises a layer of high-density foam.
27. The helmet of claim 26, wherein the high-density foam forms an
inner layer adapted to contact the user's head and the
three-dimensional spacer fabric forms an outer layer that is
adapted to attach to the inner surface of the shell.
28. The helmet of claim 19, wherein the at least one pad further
comprises another three-dimensional spacer fabric and wherein a
first of the three-dimensional spacer fabrics forms an inner layer
adapted to contact the user's head and a second of the
three-dimensional spacer fabrics forms an outer layer that is
adapted to attach to the inner surface of the shell.
29. An inner liner adapted for use with a shell of a protective
helmet, the liner comprising: at least one pad that includes a
three-dimensional spacer fabric comprising spaced layers of
material that are connected by fibers that extend between the
layers in a direction generally perpendicular to the layers, the
fibers being adapted to absorb lateral and rotational shear
forces.
30. The helmet of claim 29, wherein the three-dimensional spacer
fabric is impregnated with a cured resin that provides rigidity to
the fabric.
31. The helmet of claim 30, wherein the resin comprises one or more
of thermoplastic polyurethane, poly caprolactum (nylon), or epoxy
resin.
32. The helmet of claim 29, wherein the spaced layers are woven
layers of material.
33. The helmet of claim 32, wherein the woven layers are weaves of
glass or polymeric fibers or yarns.
34. The helmet of claim 29, wherein the fibers that extend between
the layers are glass or polymer fibers.
35. The helmet of claim 29, wherein the fibers that extend between
the layers are curved.
36. The helmet of claim 29, wherein the at least one pad further
comprises a layer of high-density foam.
37. The helmet of claim 36, wherein the high-density foam forms an
inner layer adapted to contact the user's head and the
three-dimensional spacer fabric forms an outer layer that is
adapted to attach to the inner surface of the shell.
38. The helmet of claim 29, wherein the at least one pad further
comprises another three-dimensional spacer fabric and wherein a
first of the three-dimensional spacer fabrics forms an inner layer
adapted to contact the user's head and a second of the
three-dimensional spacer fabrics forms an outer layer that is
adapted to attach to the inner surface of the shell.
39. A method for attenuating rotational acceleration of the head,
the method comprising: wearing a protective helmet comprising an
outer shell, an inner liner having one or more pads, and means for
enabling the shell to rotate relative to the head, the means
excluding cell-based foam.
40. The method of claim 39, wherein the means for enabling the
shell to rotate comprise means for enabling at least one pad to
slide within and relative to the shell.
41. The method of claim 39, wherein the means for enabling the
shell to rotate comprise at least one pad that includes a
three-dimensional spacer fabric comprising spaced layers of
material that are connected by fibers that extend between the
layers in a direction generally perpendicular to the layers, the
fibers being adapted to absorb lateral and rotational shear forces.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to co-pending U.S.
Provisional Application Ser. No. 61/482,967, filed May 5, 2011,
which is hereby incorporated by reference herein in its
entirety.
BACKGROUND
[0002] Sports concussion and traumatic brain injury have become
important issues in both the athletic and medical communities. As
an example, in recent years there has been much attention focused
on the mild traumatic brain injuries (concussions) sustained by
professional and amateur football players, as well as the long-term
effects of such injuries. It is currently believed that repeated
brain injuries such as concussions may lead to diseases later in
life, such as depression, chronic traumatic encephalophathy (CTE),
and amyotrophic lateral sclerosis (ALS).
[0003] Protective headgear, such as helmets, is used in many sports
to reduce the likelihood of brain injury. Current helmet
certification standards are based on testing parameters that were
developed in the 1960s, which focus on the attenuation of linear
impact and prevention of skull fracture. An example of a linear
impact is a football player taking a direct hit to his helmet from
a direction normal to the center of his helmet or head. Although
the focus of headgear design has always been on attenuating such
linear impact, multiple lines of research in both animal models and
biomechanics suggest that both linear impact and rotational
acceleration play important roles in the pathophysiology of brain
injury. Although nearly every head impact has both a linear
component and a rotational component, rotational acceleration is
greatest when a tangential blow is sustained. In some cases, the
rotational acceleration from such blows can be substantial. For
instance, a football player's facemask can act like a lever arm
when impacted from the side, and can therefore apply large
torsional forces to the head, which can easily result in brain
trauma.
[0004] Although the conventional wisdom is that the components of
modern protective headgear that are designed to attenuate linear
impact inherently attenuate rotational acceleration, the reality is
that such components are not designed for that purpose and
therefore do a relatively poor job of attenuating rotational
acceleration. It therefore can be appreciated that it would be
desirable to have a system and method for attenuating not only
linear impact to but also rotational acceleration of the head, so
as to reduce the likelihood of brain injury.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present disclosure may be better understood with
reference to the following figures. Matching reference numerals
designate corresponding parts throughout the figures, which are not
necessarily drawn to scale.
[0006] FIG. 1 is a front perspective view of a first embodiment of
a protective helmet.
[0007] FIG. 2 is a rear perspective view of the helmet of FIG.
1.
[0008] FIG. 3 is a bottom view of the helmet of FIG. 1 illustrating
an interior of the helmet.
[0009] FIG. 4 is a cross-sectional side view of the helmet of FIG.
1.
[0010] FIG. 5 is an exploded perspective view of the helmet of FIG.
1 clearly illustrating both a shell and a liner of the helmet.
[0011] FIG. 6 is a further cross-sectional side view of the helmet
of FIG. 1 with the liner of the helmet removed.
[0012] FIG. 7A is a front view of the helmet of FIG. 1 as worn by a
user before a torsional impact.
[0013] FIG. 7B is a front view of the helmet of FIG. 1 as worn by a
user after a torsional impact.
[0014] FIG. 8A is a cross-sectional top view of the helmet as worn
by a user before a torsional impact.
[0015] FIG. 8B is a cross-sectional top view of the helmet as worn
by a user after a torsional impact.
[0016] FIG. 9 is a cross-sectional perspective view of a second
embodiment of a protective helmet.
[0017] FIG. 10 is a cross-sectional view of a first embodiment of a
rail system that can facilitate relative motion between the liner
and the shell of a helmet.
[0018] FIG. 11 is a cross-sectional view of a second embodiment of
a rail system that can facilitate relative motion between the liner
and the shell of a helmet.
[0019] FIG. 12 is a cross-sectional side view of an embodiment of
an isolation bushing that can be incorporated into a protective
helmet to attenuate rotational acceleration.
[0020] FIG. 13 is a front perspective view of a third embodiment of
a protective helmet.
[0021] FIG. 14 is a rear perspective view of the helmet of FIG.
13.
[0022] FIG. 15 is a bottom view of the helmet of FIG. 13
illustrating an interior of the helmet.
[0023] FIG. 16 is a cross-sectional side view of the helmet of FIG.
13.
[0024] FIG. 17 is a cross-sectional perspective view of the helmet
of FIG. 13.
[0025] FIG. 18 is a side view of a first embodiment of a pad that
can be used in a liner of a protective helmet.
[0026] FIG. 19 is a perspective view of an embodiment of a
three-dimensional spacer fabric that can be used to form the pad of
FIG. 18.
[0027] FIG. 20 is a side view of a second embodiment of a pad that
can be used in a liner of a protective helmet.
[0028] FIG. 21 is a side view of a third embodiment of a pad that
can be used in a liner of a protective helmet.
[0029] FIG. 22 is a side view of a fourth embodiment of a pad that
can be used in a liner of a protective helmet.
[0030] FIG. 23 is a side view of a fifth embodiment of a pad that
can be used in a liner of a protective helmet.
DETAILED DESCRIPTION
[0031] As described above, current protective headgear is primarily
designed to attenuate linear impact. However, it has been
determined that both linear impact and rotational acceleration from
torsional forces contribute to brain injury, such as concussion.
Disclosed herein are systems and methods for attenuating rotational
acceleration that results from impacts to the head. The systems can
take the form of protective headgear, such as helmets, that
comprise an outer shell and an inner liner that enable the shell to
rotate relative to the head to reduce rotational acceleration of
the head and brain that can occur from impacts. In some
embodiments, the liner or a portion of the liner can move relative
to the shell to decouple the shell from the liner and the wearer's
head. In other embodiments, the liner includes material that is
specifically designed to yield to tangential forces and therefore
enables the shell to rotate relative to the wearer's head. In both
cases, rotational forces applied to the helmet from impacts are not
directly transmitted to the head. Instead, those forces are
dissipated over time to reduce brain shear.
[0032] In the following disclosure, various embodiments are
described. It is to be understood that those embodiments are
example implementations of the disclosed inventions and that
alternative embodiments are possible. All such embodiments are
intended to fall within the scope of this disclosure.
[0033] Described in the following disclosure are solutions to the
problem of rotational acceleration of the brain that results from
impact to the head. More particularly, disclosed are dynamic head
suspension systems that directly address tangential forces that
cause the highest shear strains on the brain and the brain stem.
Two general solutions are described below. In a first solution, a
liner provided within a helmet shell can slide within the shell so
as to enable relative rotational motion between the shell and the
liner. In addition, one or more elements are provided within the
shell that absorb the rotational force so that it is not directly
transmitted to the head. In a second solution, an engineered
material with desirable shear properties is used within the helmet
shell. The engineered material can form part of the liner and is
specifically designed to attenuate and dissipate rotational energy
from impacts to the head by undergoing controlled lateral and/or
rotational shear, thus absorbing rotational energy and dissipating
it over time before transmission to the head and the cerebrum. In
both solutions, the dynamic head suspension system can be modular
in design, enabling adaptability for use in a wide range of helmets
and other protective headgear. By optimizing protection from both
linear impacts and rotational acceleration, both solutions decrease
the transmission of shear force to the brain and therefore lower
the incidence of brain injury, such as concussion.
[0034] FIGS. 1-8 illustrate a first embodiment of a protective
helmet 10 that is designed to attenuate both linear impact and
rotational acceleration. The helmet 10 is an example embodiment of
the first solution and therefore comprises a liner that can slide
relative to the shell.
[0035] Beginning with FIGS. 1-5, the helmet 10 is generally
configured as an American football helmet. Although that particular
configuration is shown in FIGS. 1-5 and other figures of this
disclosure, it is to be understood that a football helmet is shown
for purposes of example only and that the shell design shown in the
figures is merely representational of an example football helmet
shell. The helmet need not be limited to use in football and
furthermore can take alternative forms. For example, the helmet 10
can be formed as another type of sports helmet or a military
helmet.
[0036] With continued reference to FIGS. 1-5, the helmet 10
generally includes an outer shell 12 and an inner liner 14. In the
illustrated embodiment, the shell 12 is shaped and configured to
surround the wearer's head with the exception of the face.
Accordingly, the shell 12, when worn, extends from a point near the
base of the wearer's skull to a point near the wearer's brow, and
extends from a point near the rear of one side of the wearer's jaw
to a point near the rear of the other side of the wearer's jaw. In
some embodiments, the shell 12 is unitarily formed from a rigid
material, such as a polymer or metal material. By way of example,
the shell 12 can be a molded acrylonitrile butadiene styrene (ABS)
or polycarbonate alloy shell.
[0037] Irrespective of the material used to construct the shell 12,
the shell includes an outer surface 16 and an inner surface 18. In
some embodiments, the shell 12 can further include one or more ear
openings 20 that extend through the shell from the outer surface 16
to the inner surface 18. The ear openings 20 are provided on each
side of the shell 12 in a position in which they align with the
wearer's ears when the helmet 10 is donned. Notably, the shell 12
can include other openings (not shown) that serve one or more
purposes, such as providing airflow to the wearer's head.
[0038] As is further shown in FIGS. 1-5, a facemask 22 can be
secured to the front of the helmet 10 to protect the face of the
wearer. In some embodiments, the facemask 22 can comprise one or
more rod-like segments that together form a protective lattice or
screen. When used, the facemask 22 can, for example, be attached to
the helmet 10 at points that align with the forehead and jaw of the
wearer when the helmet is worn. The facemask 22 can be attached to
the helmet 10 using screws (not shown) that thread into the shell
12 or into fastening elements (not shown) that are attached to the
helmet. Although a particular facemask configuration is shown in
the figures, alternative configurations are possible. Moreover, the
facemask 22 can be replaced with a face shield or other protective
element, if desired.
[0039] The liner 14 generally comprises one or more pads that sit
between the shell 12 and the wearer's head when the helmet 10 is
worn. In the illustrated embodiment, those pads include a top pad
24, opposed lateral pads 26, a rear pad 28, and opposed forward
pads 30. The top pad 24 is adapted to protect the top of the
wearer's head. In the illustrated embodiment, the top pad 24 is
elongated in a direction that extends along the sagittal plane of
the wearer so as to extend from a rear top portion of the head to a
front top portion of the head. The top pad 24 is further curved to
generally follow the curvature of the wearer's head. Accordingly,
the top pad 24 forms a concave inner surface 32 that is adapted to
contact the wearer's head.
[0040] The lateral pads 26 are adapted to protect the sides of the
wearer's head. The lateral pads 26 are generally rectangular and
extend from the edges of the wearer's face to points behind (and
above) the user's ears. Each lateral pad 26 includes a void 34 that
provides space for an ear of the wearer. Like the top pad 24, the
lateral pads 26 are curved to follow the curvature of the wearer's
head. Accordingly, the lateral pads 26 form concave inner surfaces
36 that are adapted to contact the wearer's head.
[0041] The rear pad 28 is adapted to protect the rear of the
wearer's head and, like the lateral pads 26, is generally
rectangular. Also like the top pad 24 and the lateral pads 26, the
rear pad 28 is curved to follow the curvature of the wearer's head
and forms a concave inner surface 36 that is adapted to contact the
wearer's head. As is apparent from the figures, the lateral edges
of the rear pad 28 comprise compression regions 40 that are adapted
to compress when the pad abuts one of the lateral pads 26 to
dissipate rotational force. For this reason, the rear pad can be
considered to function as a force dissipation pad. In the
illustrated embodiment, the compression regions 40 comprise
vertical grooves 42 that are formed in the rear pad 28 to reduce
the amount of material near the lateral edges of the pad to enable
those edges to more easily compress inward toward the center of the
pad. The purpose behind this functionality is described below in
the discussion of the use of the helmet 10 in relation to FIGS. 7
and 8. The formation of the grooves 42 results in the creation of
vertical ridges 43 that extend from the top of the rear pad 28 to
the bottom of the rear pad.
[0042] The forward pads 30 are positioned within the shell 12 so as
to protect the sides of the wearer's face, for example the cheek
and jaw region of the face. In the illustrated embodiment, the
forward pads 30 are generally oval and, like the other pads, are
curved to follow the curvature of the wearer's head. The forward
pads 30 therefore form concave inner surfaces 44 that are adapted
to contact the wearer.
[0043] Each of the above-described pads of the liner 14 can be
formed of a dense, resilient material that absorbs linear forces.
In some embodiments, the pads are made of a high-density foam
material such as polyurethane, ethylene-vinyl acetate (EVA), or
expanded polypropylene. In further embodiments, the foam can have
be variable density foam. Regardless, the top pad 24, rear pad 28,
and the forward pads 30 can be securely affixed to the inner
surface 18 of the shell 12 so that they will not move relative to
the shell when the helmet is used. In some embodiments, those pads
are secured to the shell 12 using a suitable adhesive such as glue,
or suitable fastening elements such as snap or hook-and-loop
fasteners. Unlike those pads, however, the lateral pads 26 are free
to move relative to the shell 12 to dissipate certain rotational
forces that act on the shell. Such movement is facilitated by a
generally horizontal raceway 46 formed on each side of the shell
12. One such raceway is illustrated in FIG. 6, which shows a
cross-section of the helmet 10 with the liner 14 removed. In the
illustrated embodiment, each raceway 46 is defined by parallel,
generally horizontal upper (first) and lower (second) ribs 48 and
50 that extend inward from the inner surface 18 of the shell 12. In
the illustrated embodiment, the upper rib 48 is positioned near the
top of the shell 12 and extends from a point near the front of the
shell to a point near the back of the shell, while the lower rib 50
is positioned near the bottom of the shell below the ear openings
20 and likewise extends from a point near the front of the shell to
a point near the back of the shell. By way of example, the ribs 48,
50 are unitarily formed with the shell 12 during a molding process
and extend inward from the shell inner surface 18 by a distance of
approximately 3 to 30 millimeters (mm).
[0044] The lateral pads 26 are sized and configured to fit within
the raceway 46 between the upper and lower ribs 48 and 50. More
particularly, the lateral pads 26 are sized and configured to be
bound along their top and bottom edges by the upper and lower ribs
48 and 50, respectively, as shown in FIG. 4. Because the lateral
pads 26 are not secured to the inner surface 18 of the shell, they
can slide forward and rearward (horizontally) along the raceways
46, at least until they abut another pad of the liner, such as the
rear pad 28. Free sliding of the lateral pads 26 can be facilitated
by providing one or both of the inner surface 52 of the raceways
and the outer surfaces 54 of the lateral pads 26 with a
low-friction surface. Such a surface can comprise a coating or a
layer of a low-friction material that is applied to one or both of
the raceway inner surfaces 52 and the pad outer surfaces 54. By way
of example, the low-friction material can comprise
polytetrafluoroethylene (PTFE). In addition or exception, a
lubricant, such as graphite powder, can be provided between the
raceway inner surfaces 52 and the lateral pad outer surfaces 54 to
encourage relative motion. In still other embodiments, friction
between the lateral pads 26 and the raceways 46 can be reduced by
incorporating friction-reducing elements, such as rollers or ball
bearings (not shown), between the lateral pads 26 and the raceways
46.
[0045] FIG. 7A illustrates the helmet 10 as worn by a wearer, such
as a football player. As is apparent from the figure, the helmet 10
is centered on the wearer's head so that the center of the facemask
22 aligns with the center of the wearer's face. FIG. 8A is a
cross-sectional top view of the helmet orientation illustrated in
FIG. 7A. These figures can be considered to show the orientation of
the helmet 10 on the wearer's head before a rotational force is
applied to the helmet.
[0046] FIGS. 7B and 8B show the orientation of the helmet 10 on the
wearer's head after a rotational force has been applied to the
helmet. The rotational force can, for example, be the result of a
blow that is sustained by the shell 12 or the facemask 22 that
causes the shell to rotate about an imaginary vertical axis,
designated herein as the z-axis, that extends through the center of
the wearer's head from bottom to top. Of course, the rotational
force may be just a component of the impact to the helmet 10 and
may be accompanied by a linear force that is imparted to the
helmet. With a conventional helmet that is adapted to fit tightly
to the wearer's head, such a rotational force would result in
immediate rotation of the head and would result in a substantial
rotational acceleration being applied to the brain. However,
because the lateral pads 26 are free to slide along the raceways
46, the shell 12 of the helmet 10 can rotate without concomitant
rotation of the wearer's head. In particular, the wearer's head and
the lateral pads 26 can remain relatively stationary, at least in
terms of rotation, while the shell 12 rotates relative to the head
and the lateral pads about the z-axis.
[0047] Such relative motion is illustrated in FIGS. 7B and 8B. In
the example of FIGS. 7B and 8B, the helmet 10 has been impacted
such that the shell 12 shifts to the right about the z-axis from
the perspective of the wearer. As can be appreciated from FIG. 8B
when compared with FIG. 8A, the lateral pads 26 remain in their
original positions on the head despite the shifting of the shell 12
because they can slide along their raceways 46. Because the other
pads of the liner 14 are secured to the inner surface 18 of the
shell 12, however, the other pads have shifted relative to the
lateral pads 26 and the head. As is shown in FIG. 8B, the rear pad
28 has shifted to the extent that it has abutted against the
left-side lateral pad 26. In particular, as is further shown in
FIG. 8B, the left side compression region 40 of the rear pad 28 has
compressed due to its collision with the left-side lateral pad 26.
This compression of the compression region 40 absorbs at least some
of the rotational force that has been applied to the shell 12 and
dissipates that force over time (albeit a short period of time) so
that less rotational acceleration is applied to the brain. This
results in less likelihood of the wearer sustaining a brain injury,
such as a concussion. Depending upon the material and dimensions of
the rear pad 28 and the compression regions 40, the rear pad may
also serve to urge the shell 12 back toward its original
orientation on the head as would a compression spring.
[0048] FIG. 9 illustrates a second embodiment of a protective
helmet 10' that comprises a liner that can slide relative to the
shell. The helmet 10' is similar in many ways to the helmet 10
illustrated in FIGS. 1-8 and described above (the top pad 24 and
the forward pads 30 are not shown for clarity). However, the helmet
10' comprises alternative lateral pads 26'. Like the lateral pads
26 of the helmet 10, the lateral pads 26' are generally rectangular
and are adapted to slide along a raceway 46 defined by upper and
lower ribs 48 and 50. In addition, the lateral pads 26 can be made
of a foam material such as polyurethane, ethylene-vinyl acetate
(EVA), or expanded polypropylene. Unlike the lateral pads 26,
however, the lateral pads 26' comprises multiple narrow, elongated
vertical ribs 56 that are separated by multiple narrow, elongated
vertical troughs 58. With such a configuration, the lateral pads
26' are adapted not only to slide relative to the shell 12 but also
to laterally deflect in the horizontal direction due to the narrow
widths of the vertical ribs 56 to further dissipate rotational
energy from impacts to the head. In embodiments in which the
vertical ribs 56 alone provide adequate rotational energy
dissipation, the lateral pads 26' can be securely affixed to the
inner surface 18 of the shell 12 such that the pads will not slide
relative to the shell.
[0049] In the embodiments of FIGS. 1-9, the lateral pads 26, 26'
slide along raceways 46 and are confined by upper and lower ribs 48
and 50. In alternative embodiments, the lateral pads 26, 26' can be
enabled to slide relative to the shell 12 using rails. FIGS. 10 and
11 illustrate two example rail systems that can be incorporated
into a helmet, such as the helmet 10. Beginning with FIG. 10, a
first rail system 60 comprises at least one rail 62 that is
provided on the inner surface 18 of the shell 12. If relative
movement of the shell 12 around the z-axis is desired, the rail 62
can be a horizontal rail. As is further shown in FIG. 9, the
lateral pad 26, 26' is provided with a groove 64 that is sized and
configured to receive the rail 62. In some embodiments, the groove
64 can be reinforced with a rigid material, such as a polymer
material (not shown). Regardless, the groove 64 can slide along the
rail 62 to enable relative movement of the lateral pad 26, 26' and
the shell 12. As with the raceway embodiments, free sliding of the
lateral pad 26, 26' can be facilitated through use of low-friction
materials and/or lubricants.
[0050] FIG. 11 illustrates a second rail system 66 that is the
inverse arrangement of that shown in FIG. 10. The second rail
system 66 comprises at least one groove 68 that is provided on the
inner surface 18 of the shell 12. If relative movement of the shell
12 around the z-axis is desired, the groove 68 can be a horizontal
groove. As is further shown in FIG. 11, the lateral pad 26, 26' is
provided with a rail 70 that is sized and configured to be received
within the groove 68. In some embodiments, the rail 70 can be
reinforced with a rigid material, such as a polymer material (not
shown). Regardless, the rail 70 can slide along the groove 68 to
enable relative movement of the lateral pad 26, 26' and the shell
12. As with the raceway embodiment, free sliding of the lateral pad
26, 26' can be facilitated through use of low-friction materials
and/or lubricants.
[0051] In the above-described helmet embodiments, movement of the
liner relative to the shell is constrained to one direction. For
example, when horizontal raceways or rails are used, the lateral
pads of the liner can only slide horizontally relative to the
helmet. In such a case, only the rotational forces about the z-axis
can be attenuated. It is noted, however, that all rotational forces
can be attenuated when the helmet includes means that enable the
pads to slide in any direction relative to the helmet. FIG. 12
illustrates an example of such means. More particularly, FIG. 12
illustrates an isolation bushing 80 that can be used to decouple a
liner pad 82 from a shell 84 of a helmet.
[0052] As is shown in FIG. 12, the pad 82, which can comprise a
foam material, is supported by a substrate 86, which can comprise a
rigid polymer material. The isolation bushing 80 comprises
compression springs 88 that are confined by stops 90 that extend
out from the inner surface 92 of the shell 84. Each spring 88
contacts a stop 90 at one end and a rib 94 that extends out from
the pad substrate 86 at the other end. With such a configuration,
the pad 82 can move from side to side (as indicated by the
double-sided arrow 96) relative to the shell 84 and the springs 88
will both absorb the force (i.e., a rotational force) causing the
relative motion and urge the pad back toward its original position
shown in FIG. 12. Notably, further springs (not shown) can be
provided in a plane parallel to the springs 88 but in a direction
normal to the springs 88 to likewise absorb forces that cause the
pad 82 to move relative to the shell 84 in a direction normal to
the arrow 96 (i.e., into an out of the page). With such an
arrangement, the pad 82 can slide in any direction that is
substantially parallel to the shell 84 and can therefore absorb any
rotational force applied to the shell irrespective of its
direction. Accordingly, the pad 82 can provide omnidirectional
rotational force absorption.
[0053] Omnidirectional rotational force absorption can be provided
with other means. FIGS. 13-23 illustrate examples of such means.
More particularly, those figures illustrate an example of the
second solution to attenuating rotational acceleration in the form
of a protective helmet that comprises a liner that incorporates one
or more engineered materials that are specifically designed to
attenuate linear impact and dissipate rotational energy from
impacts to the head by undergoing controlled lateral and/or
rotational shear.
[0054] Illustrated in FIGS. 13-17 is a third embodiment of a
protective helmet 100. The helmet 100 is similar to the helmet 10
and therefore similar components will only briefly be described.
The helmet 100 generally includes an outer shell 102 and an inner
liner 104. The shell 102 is shaped and configured to surround the
wearer's head with the exception of the face and can be unitarily
formed from a rigid material such as ABS or polycarbonate
alloy.
[0055] Irrespective of the material used to construct the shell
102, the shell includes an outer surface 106 and an inner surface
108. In some embodiments, the shell 102 can further include one or
more ear openings 110 that extend through the shell from the outer
surface 106 to the inner surface 108. A facemask 112 can be secured
to the front of the helmet 100 to protect the face of the wearer
and can be attached to the helmet 100 using screws (not shown) that
thread into the shell 102 or into fastening elements (not shown)
that are attached to the helmet.
[0056] The liner 104 generally comprises one or more pads that sit
between the shell 102 and the wearer's head when the helmet 100 is
worn. In the illustrated embodiment, those pads include a top pad
114, a rear pad 116, a front pad 118, rear lateral pads 120, upper
lateral pads 122, and lower lateral pads 124. In the illustrated
embodiment, each of the pads has an inner component or layer and
one or more outer components or layers, with the inner layers being
adapted to contact the wearer's head and the outer layers being
adapted to attach to the inner surface 108 of the shell 102. As in
the previous embodiments, each pad can be curved to adapt to the
curvature of the wearer's head. Therefore, the inner layer of each
pad can have a concave inner surface.
[0057] The nature of the inner and outer layers of each pad of the
liner 104 can be selected to achieve whatever characteristics that
are desired. In one embodiment, the inner layers are composed of a
foam material to absorb linear forces and the outer layers are
composed of a three-dimensional spacer fabric that comprises no
cell-based foam and that is adapted to absorb both linear impact
and lateral and/or rotational shear forces. FIG. 18 illustrates an
example of one such configuration of pad 130. Such a configuration
can be used, for example, for the top pad 114, the rear lateral
pads 120, the upper lateral pads 122, and the lower lateral pads
124 of the helmet 100. As is shown in FIG. 18, the pad 130
comprises a relatively thin inner layer 132 and a relatively thick
outer layer 134. By way of example, the outer layer 134 can be
approximately 15 to 30 mm thick and the inner layer 132 can be
approximately 3 to 15 mm thick.
[0058] As mentioned above, the inner layer 132 can be made of a
foam material and the outer layer 134 can be made of a
three-dimensional spacer fabric. An example of a suitable
three-dimensional spacer fabric is illustrated in FIG. 19. As is
shown in that figure, the three-dimensional spacer fabric 140
comprises a top layer of material 142 that is separated from a
parallel bottom layer of material 144. The two layers 142, 144 can
each be a woven fabric that comprises a plurality of glass or
polymer fibers aligned in both the warp and the weft directions of
the fabric. In some embodiments, the fibers are combined to form
multiple yarns that are woven together to form the fabric. By way
of example, the three-dimensional spacer fabric 140 is
approximately 8 to 20 mm thick and the layers 142, 144 comprise
yarns that have approximately 400 to 600 individual filaments and
that range from approximately 65 to 300 tex. Each filament is
approximately 8 to 13 microns (.mu.m) in diameter. In some
embodiments, the layers 142, 144 have approximately 60 to 80 pick
ends and approximately 60 to 70 warp ends per square 10 mm.
[0059] Extending between the two layers of material 142, 144 in a
direction generally perpendicular to the layers are multiple glass
or polymer fibers 146 that maintain the separation between the two
layers and absorb lateral and rotational shear forces. In some
embodiments, the fibers 146 are combined to form multiple yarns
that extend between the two layers. By way of example, each fiber
or yarn has similar characteristics to those used to form the
layers 142, 144. Regardless, the fibers or yarns 146 are coupled to
the layers 142, 144. In some embodiments, the fibers or yarns 146
are alternately threaded through the top and bottom layers 142, 144
in a continuous fashion so that each fiber or yarn can have
multiple lengths that extend between the two layers. As can be
appreciated from FIG. 19, those lengths can be curved. More
particularly, the lengths can form S-shapes and inverted S-shapes
that, when viewed together from an end of the fabric 140, form a
repeating figure-8 pattern (see FIG. 18).
[0060] In some embodiments, the fibers used to construct the
three-dimensional spacer fabric are fiberglass or aramid fibers.
One commercial example of such a three-dimensional spacer fabric
140 is Parabeam.TM. material available from Parabeam b.v. in The
Netherlands. Before the three-dimensional spacer fabric 140 is used
to form a pad, the top and bottom layers 142, 144 are separated and
fabric is impregnated with a polymeric resin, such as thermoplastic
polyurethane, poly caprolactum (nylon), or epoxy resin, so as to
coat the fibers and threads in resin. The resin can be applied
using a vacuum infusion process and then cured to govern the
rigidity of the end material, from very flexible to very rigid.
This structural integrity or rigidity provided by the cured resin
is what enables the three-dimensional spacer fabric 140 to absorb
both linear impact and shear forces. In some embodiments, the
finished three-dimensional spacer fabric 140 has a shear strength
of approximately 15 to 25 pounds per square inch (psi) and a shear
modulus of approximately 250 to 350 psi. In one example embodiment,
an infusible low 800 to 1,000 centipoise thermoplastic polyurethane
resin can be used to produce a three-dimensional spacer fabric
having compression and shear characteristics that are approximately
equivalent to a 40 to 100 A durometer shore hardness material. Such
a fabric possesses substantially instantaneous spring-back
characteristics following compression or shear deformation.
[0061] Referring back to FIG. 18, the combination of the foam inner
layer 132 and the three-dimensional spacer fabric outer layer 134
results in a pad 130 that is both well suited to absorb linear and
rotational forces, thereby greatly reducing the opportunity for
brain injury. Unlike the raceway and rail embodiments discussed
above, helmets that incorporate pads such as the pad 130 are
adapted to absorb all rotational forces imposed upon the shell and
not just those about the z-axis of the head. Therefore, helmets
such as the helmet 100 can provide even greater protection against
harmful rotational accelerations.
[0062] FIG. 20 illustrates another example of a pad 150 that can be
incorporated into a helmet such as the helmet 100. Such a
configuration can be used, for example, for the rear pad 116 and
the front pad 118 of the helmet 100. As is shown in FIG. 20, the
pad 150 comprises a relatively thick inner layer 152 and two outer
layers 154. The inner layer 152 can be made of a foam material and
the outer layers 154 can be made of a three-dimensional spacer
fabric. In the embodiment of FIG. 20, the inner layer 152 is
thicker to better absorb linear impacts, which may be received with
greater frequency from the front and the rear of the helmet. The
outer layers 154 can be relatively narrow (see also FIGS. 16 and
17) such that they provide greater rotational force attenuation in
the horizontal direction than in the vertical direction.
[0063] FIG. 21 illustrates a pad 160 that is a variation on the pad
150. The pad 160 comprises a relatively thick inner layer 162 and a
single outer layer 164. The inner layer 162 can be made of a foam
material and the outer layer 164 can be made of a three-dimensional
spacer fabric. In the embodiment of FIG. 21, the outer layer 164
has a width that is smaller than that of the inner layer 162. This
arrangement illustrates that one can alter the amount of
three-dimensional spacer fabric used in a pad to provide the
desired characteristics of energy attenuation.
[0064] FIG. 22 illustrates a further pad 170 that can be used in a
helmet like the helmet 100. The pad 170 is similar to the pad 130
of FIG. 18 and therefore comprises a foam inner layer 172 and a
three-dimensional spacer fabric outer layer 174. In the embodiment
of FIG. 22, however, the inner layer 172 comprises two distinct
foam layers 176 and 178. By way of example, the inner foam layer
176 can have a lower density than the outer foam layer 178 so that
the inner layer 172 provides the comfort the wearer desires as well
as the force absorption that is required to protect his brain from
injury.
[0065] FIG. 23 illustrates a further variation on the pad 130. Like
the pad 130, the pad 180 comprises an inner layer 182 and an outer
layer 184. In this embodiment, however, the inner layer 182 is a
further layer of three-dimensional spacer fabric like the outer
layer 184. In some embodiments the inner layer 182 is the same as
the outer layer 184 but is less thick, which changes its
compression and/or shear properties. In other embodiments, the
inner layer 182 can have different fibers, yarns, resin, or other
aspects that alter its compression and/or shear properties.
[0066] In the foregoing disclosure, various embodiments have been
described. As was noted above, alternative embodiments are
possible. As an example, although multiple embodiments have been
described as having liners comprising multiple discrete pads, in
alternative embodiments one or more of the pads can be combined.
For instance, one or more of the pads that surround the sides and
back of the head can be combined and the combined pad can slide as
a whole relative to the shell. As another example, various discrete
aspects of the disclosed embodiments can be combined to form other
embodiments. For instance, the lateral pads of the embodiments of
FIGS. 1-9 can include the three-dimensional spacer fabric of the
embodiment of FIGS. 13-17 to provide a further means of dissipating
rotational force. All such alternative embodiments are deemed to
fall within the scope of this disclosure.
* * * * *