U.S. patent application number 13/803962 was filed with the patent office on 2014-01-16 for protective helmet for mitigation of linear and rotational acceleration.
This patent application is currently assigned to Apex Biomedical Company LLC. The applicant listed for this patent is APEX BIOMEDICAL COMPANY LLC. Invention is credited to Michael Bottlang, Nathan Dau, Kirk Hansen, Steven Madey, Ashton Wackym.
Application Number | 20140013492 13/803962 |
Document ID | / |
Family ID | 49912644 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140013492 |
Kind Code |
A1 |
Bottlang; Michael ; et
al. |
January 16, 2014 |
PROTECTIVE HELMET FOR MITIGATION OF LINEAR AND ROTATIONAL
ACCELERATION
Abstract
Embodiments provide protective helmets configured to protect the
head from linear and rotational acceleration in an impact. In
various embodiments, the helmets may include an outer layer, an
inner layer, and at least one intermediate layer coupled to the
outer and inner layers by alternate fixation sites, thereby
providing a suspension between the outer and inner layers. In
various embodiments, the intermediate layer may be made from a
honeycomb material, such as an aluminum honeycomb. In use, in-plane
deformation of the honeycomb may allow for translation of the outer
layer in a substantially tangential direction relative to the inner
layer, thereby mitigating rotational acceleration imparted by the
tangential impact component. Additionally, crumpling of the
honeycomb in a substantially non-elastic manner may deplete impact
energy to minimize the elastic rebound that can contribute to
linear and rotational head acceleration, thereby mitigating linear
acceleration imparted by the perpendicular impact component.
Inventors: |
Bottlang; Michael;
(Portland, OR) ; Madey; Steven; (Portland, OR)
; Dau; Nathan; (Portland, OR) ; Hansen; Kirk;
(Portland, OR) ; Wackym; Ashton; (Portland,
OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
APEX BIOMEDICAL COMPANY LLC |
Portland |
OR |
US |
|
|
Assignee: |
Apex Biomedical Company LLC
Portland
OR
|
Family ID: |
49912644 |
Appl. No.: |
13/803962 |
Filed: |
March 14, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61670258 |
Jul 11, 2012 |
|
|
|
Current U.S.
Class: |
2/414 ;
2/411 |
Current CPC
Class: |
A42B 3/124 20130101;
A42B 3/125 20130101; A42B 3/064 20130101; A42B 3/065 20130101 |
Class at
Publication: |
2/414 ;
2/411 |
International
Class: |
A42B 3/12 20060101
A42B003/12 |
Claims
1. A helmet for protecting a head during an impact, comprising: an
outer layer; an inner layer; and at least one deformable
intermediate layer, wherein the intermediate layer has
substantially no elastic rebound, and wherein the intermediate
layer is coupled to both the outer and inner layers at alternate
fixation sites.
2. The helmet of claim 1, wherein the intermediate layer is
configured to provide a suspension between the outer and inner
layers.
3. The helmet of claim 1, wherein the outer layer is configured to
translate in a substantially tangential direction relative to the
inner layer via in-plane deformation of at least a portion of the
intermediate layer.
4. The helmet of claim 3, wherein the intermediate layer is
configured to absorb impact energy by deformation in directions
both perpendicular and tangential to the outer layer.
5. The helmet of claim 3, wherein the outer layer is further
configured to translate in a direction substantially perpendicular
to the inner layer.
6. The helmet of claim 1, wherein the helmet further comprises a
glidable interface layer disposed between the intermediate layer
and the inner and/or outer layer, wherein the glidable interface
layer is configured to facilitate sliding between the intermediate
layer and the inner and/or outer layer.
7. The helmet of claim 1, wherein the inner, outer, and/or
intermediate layer comprises a colorimetric indicator configured to
indicate the severity of an impact sustained by the helmet.
8. The helmet of claim 1, wherein an alternate fixation site
between the intermediate layer and the inner or outer layer
comprises a unidirectional coupling, and wherein the unidirectional
coupling permits tangential translation at the unidirectional
coupling site between the intermediate layer and in the inner or
outer layer in only one direction.
9. The helmet of claim 8, wherein the unidirectional coupling is
configured such that a tangential impact deforms the intermediate
layer only in compression, and not in tension.
10. The helmet of claim 8, wherein the unidirectional coupling
comprises an edge or hook on the inner and/or outer layer that
overlaps at least a portion of the intermediate layer.
11. The helmet of claim 1, wherein the outer and/or inner layer is
perforated with a plurality of holes having an average diameter of
from about 1 mm to about 3 cm.
12. The helmet of claim 1, wherein the alternate fixation sites
comprise removable couplings.
13. The helmet of claim 1, wherein the alternate fixation sites
comprise elastic couplings, and wherein the elastic couplings are
configured to allow relative displacement between the inner layer
and outer layer in an impact.
14. A helmet for protecting a head during an impact, comprising: an
outer layer; an inner layer; and at least one deformable
intermediate layer, wherein the intermediate layer comprises a
honeycomb, and wherein the helmet is configured to permit relative
tangential displacement of the inner and/or outer layers with
respect to one another.
15. The helmet of claim 14, wherein the honeycomb is an aluminum
honeycomb.
16. The helmet of claim 14, wherein the honeycomb comprises a
plurality of honeycomb elements configured to retain a
substantially symmetric shape and/or resist buckling when the
intermediate layer adopts a curved or substantially spherical
shape.
17. The helmet of claim 14, wherein the honeycomb is configured to
crumple and absorb an impact force component actin substantially
perpendicular to the outer layer.
18. The helmet of claim 17, wherein the honeycomb provides a
substantially linear crush response.
19. The helmet of claim 17, wherein the honeycomb is pre-crushed by
1-20% of its thickness.
20. The helmet of claim 14, wherein the intermediate layer
comprises at least two layers of honeycomb, wherein each layer of
honeycomb has a different crush resistance.
21. The helmet of claim 14, wherein the honeycomb cells are at
least partially filled with an additional energy-absorbing
material.
22. The helmet of claim 21, wherein the additional energy-absorbing
material comprises an expanded foam.
23. The helmet of claim 21, wherein the additional energy-absorbing
material has a non-uniform thickness, and wherein the additional
energy-absorbing material is configured such that the intermediate
layer becomes progressively more crush-resistant as it is crushed
in a direction tangential to the outer layer and/or in a direction
perpendicular to the outer layer.
24. The helmet of claim 14, wherein the outer layer and/or inner
layer is permeable to air and configured to allow for ventilation
through the honeycomb.
25. A method for making a helmet that mitigates linear and
rotational acceleration of a head during impact, the method
comprising: suspending an intermediate layer between an outer layer
and an inner layer, wherein suspending the intermediate layer
comprises coupling the intermediate layer to the inner layer and
the outer layer at alternate fixation sites, wherein the
intermediate layer is configured to absorb impact energy by
deformation in a direction perpendicular to the outer layer and in
a direction tangential to the outer layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Patent
Application No. 61/670,258, filed Jul. 11, 2012, entitled
"PROTECTIVE HELMET FOR MITIGATION OF LINEAR AND ROTATIONAL
ACCELERATION," the entire disclosure of which is hereby
incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments herein relate to the field of protective helmets
and, more specifically, to helmets designed to protect the head
from linear and rotational acceleration
BACKGROUND
[0003] Helmets protect the head from injury during a direct impact.
An impact to the head can cause skull fracture and/or traumatic
brain injury (TBI), and TBI is the leading cause of death and
long-term disability in the US among people under 45. 90% of
traumatic brain injuries occur without the presence of a skull
fracture, and TBI can be induced by rotational acceleration alone.
Despite the vulnerability of the brain to rotational acceleration,
contemporary bicycle helmets are primarily designed and tested to
mitigate linear acceleration. Most contemporary helmets have two
principal shortcomings: first, they have limited means to absorb
rotational acceleration, and second, elastic helmet liners may
store energy during impact, and release of the stored energy may
induce a rebound after impact that may contribute to the severity
and duration of rotational head acceleration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Embodiments will be readily understood by the following
detailed description in conjunction with the accompanying drawings.
Embodiments are illustrated by way of example and not by way of
limitation in the figures of the accompanying drawings.
[0005] FIG. 1 illustrates a cross-sectional mid-sagittal view of an
example of a helmet, shown in an unloaded, non-deformed
configuration, in accordance with various embodiments;
[0006] FIG. 2 illustrates a cross-sectional mid-sagittal view of a
helmet shown during impact in a loaded, partially deformed
configuration, and depicting relative translation between the outer
and inner layers, accommodated by in-plane compression and tension
of the intermediate layer, in accordance with various
embodiments;
[0007] FIGS. 3A and 3B illustrate non-elastic, plastic deformation
of an example of a honeycomb membrane, shown in non-deformed (FIG.
3A) and deformed (FIG. 3B, with cut-away) states, in accordance
with various embodiments;
[0008] FIGS. 4A and 4B illustrate schematic drawings of a planar
segment (FIG. 4A) and a spherically shaped segment (FIG. 4B) of an
exemplary honeycomb configuration that enables spherical,
three-dimensional shaping, in accordance with various
embodiments;
[0009] FIGS. 5A, 5B, and 5C depict a schematic drawing of a
honeycomb layer segment with alternate fixation points, shown in
unloaded (FIG. 5A) and loaded, deformed conditions (FIG. 5B), and a
perspective view of the honeycomb layer in a loaded, deformed
condition (FIG. 5C), in accordance with various embodiments;
[0010] FIG. 6 illustrates a cross-sectional mid-sagittal view of an
exemplary helmet shown in conjunction with additional layer
segments adjacent to the intermediate layer to facilitate sliding
of the intermediate layer relative to the inner and outer layers,
in accordance with various embodiments;
[0011] FIG. 7 illustrates a cross-sectional mid-sagittal view of
one embodiment of a helmet, shown during impact in a loaded,
partially deformed configuration, in accordance with various
embodiments; and
[0012] FIG. 8 illustrates a cross-sectional view of a section of
another embodiment, wherein the outer layer and inner layer are
perforated with a multitude of holes, which may allow for
ventilation through the honeycomb cells, in accordance with various
embodiments.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0013] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and in which
are shown by way of illustration embodiments that may be practiced.
It is to be understood that other embodiments may be utilized and
structural or logical changes may be made without departing from
the scope. Therefore, the following detailed description is not to
be taken in a limiting sense, and the scope of embodiments is
defined by the appended claims and their equivalents.
[0014] Various operations may be described as multiple discrete
operations in turn, in a manner that may be helpful in
understanding embodiments; however, the order of description should
not be construed to imply that these operations are order
dependent.
[0015] The description may use perspective-based descriptions such
as up/down, back/front, and top/bottom. Such descriptions are
merely used to facilitate the discussion and are not intended to
restrict the application of disclosed embodiments.
[0016] The terms "coupled" and "connected," along with their
derivatives, may be used. It should be understood that these terms
are not intended as synonyms for each other. Rather, in particular
embodiments, "connected" may be used to indicate that two or more
elements are in direct physical with each other. "Coupled" may mean
that two or more elements are in direct physical or electrical
contact. However, "coupled" may also mean that two or more elements
are not in direct contact with each other, but yet still cooperate
or interact with each other.
[0017] For the purposes of the description, a phrase in the form
"A/B" or in the form "A and/or B" means (A), (B), or (A and B). For
the purposes of the description, a phrase in the form "at least one
of A, B, and C" means (A), (B), (C), (A and B), (A and C), (B and
C), or (A, B and C). For the purposes of the description, a phrase
in the form "(A)B" means (B) or (AB) that is, A is an optional
element.
[0018] The description may use the terms "embodiment" or
"embodiments," which may each refer to one or more of the same or
different embodiments. Furthermore, the terms "comprising,"
"including," "having," and the like, as used with respect to
embodiments, are synonymous.
[0019] Embodiments herein provide protective helmets designed to
lessen the amount of harmful acceleration (both straight linear and
rotational) that reaches the brain of a wearer during an impact to
the head. In various embodiments, the helmets may include a
multilayer construction for both cushioning and absorbing impact
and rotational energy, thus reducing peak acceleration or
deceleration of a wearer's head in an impact. In various
embodiments, this reduction in head acceleration and deceleration
may result in a corresponding reduction in the magnitude of
acceleration or deceleration experienced by the brain, reducing the
risk and/or severity of traumatic brain injury (TBI).
[0020] In various embodiments, the helmets disclosed herein may
include a suspension of a compressible intermediate layer suspended
between generally non-compressible inner and outer layers. In
various embodiments, the suspension of the compressible
intermediate layer may mitigate transfer of rotational acceleration
from the outer layer to the inner layer. In various embodiments,
the suspension may be created by coupling the compressible
intermediate layer, such as a honeycomb layer, through discrete,
alternate (e.g., non-opposing) fixation sites, to the outer and
inner helmet layers in a manner that allows substantially
tangential translation of the outer layer relative to the inner
layer. Thus, in various embodiments, translation of the outer layer
relative to the inner layer may induce in-plane compression and
tension in the intermediate layer, rather than shearing.
[0021] In various embodiments, in addition to providing a
suspension between the inner and outer layers, the intermediate
layer also may crumple and/or compress in an essentially
non-elastic manner to mitigate linear acceleration by depleting
impact energy and minimizing elastic rebound, which can otherwise
contribute to linear and rotational head acceleration. As such, in
various embodiments, the disclosed helmets may allow tangential
impact components to be absorbed by in-plane compressive or tensile
deformation of the intermediate layer, and perpendicular impact
components to be absorbed by non-elastic crumpling/compression of
the intermediate layer.
[0022] In various embodiments, the intermediate layer may include a
honeycomb, such as a honeycomb formed from any material having
little or no elastic rebound. For example, in various embodiments,
the honeycomb may be formed from compressible aluminum elements.
Although the examples illustrated herein use aluminum honeycombs,
one of skill in the art will appreciate that other lightweight,
compressible materials may be employed that have little or no
elastic rebound, such as cardboard or paper pulp, various natural
or synthetic foams (such as aluminum foam), plastic, non-elastic
polymers, and the like.
[0023] In various embodiments, the layered construction of the
helmets disclosed herein may be used to construct any type of
protective headgear, such as safety helmets, motorcycle helmets,
bicycle helmets, ski helmets, lacrosse helmets, hockey helmets,
football helmets, batting helmets for baseball and softball,
headgear for rock and mountain climbers, headgear for boxers,
construction helmets, helmets for defense and military
applications, and headgear for underground activities. In other
embodiments, the layered technologies disclosed herein may be
adapted for use in other types of protective gear, such as elbow
pads, knee pads, shoulder pads, shin guards, and the like.
[0024] FIG. 1 illustrates a cross-sectional mid-sagittal view of an
example of a helmet, shown in an unloaded, non-deformed
configuration, in accordance with various embodiments. In the
illustrated embodiment, the helmet 101 has an aerodynamic shape
designed for use by bicyclists. As illustrated, helmet 101 may
include an outer layer 104, an inner layer 105, and an intermediate
layer 102. In various embodiments, intermediate layer 102 may be
made from a honeycomb material, such as an aluminum honeycomb
material, and may be coupled to the outer and inner layers 104, 105
at alternate fixation sites 103a, 103b, 103c. As defined herein,
the term "alternate fixation sites" refers to attachment points
between the outer and intermediate layers, or the intermediate and
inner layers, that are spaced apart such that the outer and
intermediate layers are not coupled together at a point directly
above (e.g., across a thickness dimension of the helmet) a fixation
site between the intermediate and inner layers. The term "alternate
fixation sites" does not require that each fixation site alternates
with respect to adjacent sites along a length of a layer. In
embodiments, there may be, for example, two fixation sites adjacent
to each other between the intermediate layer 102 and the outer
layer 104 and one or more fixation sites between the intermediate
layer 102 and the inner layer 105 further in one direction along
the layers. In various embodiments, these alternate fixation sites
103a, 103b, 103c may be positioned such that intermediate layer 102
is not coupled to both the outer and inner layers 104, 105 at
opposing locations of intermediate layer 102, so that, for example,
a fixation site 103b between intermediate layer 102 and outer layer
104 is not directly opposed to a fixation site 103a, 103c between
intermediate layer 102 and inner layer 105, and vice versa. In
various embodiments, this alternate fixation may leave portions of
intermediate layer 102 that are coupled to neither outer layer 104
nor inner layer 105, enabling stretching and/or compression of
intermediate layer 102 between alternate fixation sites 103a, 103b,
103c, thus enabling translation of outer layer 104 relative to
inner layer 105, as described in greater detail below.
[0025] In various embodiments, outer helmet layer 104 may be
sufficiently stable, rigid, and/or non-compressible to distribute
impact forces over an extended area. One of skill in the art will
appreciate that the shape depicted in FIG. 1 is merely exemplary,
and that the helmet shape can vary depending on the particular
sporting event or activity for which the helmet is designed.
Furthermore, helmets in accordance with the present disclosure may
include additional features, such as a cage for a hockey helmet, a
face mask for a football helmet, a visor for a motorcycle helmet,
and/or retention straps, chin straps, and the like. Although not
shown in the illustrated embodiment, inner, intermediate, and/or
outer layers 105, 102, 104 may include one or more ventilation
openings to permit air flow for cooling the wearer's head.
[0026] In the illustrated embodiment, intermediate layer 102 may
include an aluminum honeycomb, arranged with its cells oriented
generally perpendicular to the outer layer 104 of the helmet. In
various embodiments, inner layer 105 may be applied to at least a
portion of the intermediate layer 102 interior surface. In
embodiments, the inner layer covers most if not all of the
intermediate layer. The inner layer may be comprised of a singular
component, of multiple, partially overlapping components, or of
multiple components that are joined together in a flexible manner
(e.g., like the sewn patches of a soccer ball). As described above,
in various embodiments, intermediate layer 102 may be coupled to
outer layer 104 and inner layer 105 at discrete and alternate
fixation sites 103a, 103b, 103c so as to provide a suspension
between outer layer 104 and inner layer 105. For example, in some
embodiments, outer layer 104 may be coupled to intermediate layer
102 at the helmet crown 103b, and inner layer 105 may be coupled to
intermediate layer 102 at the helmet periphery 103a, 103c. Without
being bound by theory, this configuration may reduce the rotational
head acceleration caused by the impact component acting tangential
to the helmet surface, and it also may reduce linear head
acceleration caused by the impact component acting perpendicular to
the helmet surface, as described in greater detail below. Other
configurations/arrangements may be used in other embodiments.
[0027] FIG. 2 illustrates a cross-sectional mid-sagittal view of a
helmet 201 shown during impact in a loaded, partially deformed
configuration, and depicting relative translation between the outer
and inner layers 204, 205, accommodated by in-plane compression and
tension of the intermediate layer 202, in accordance with various
embodiments. In the illustrated embodiment, as described above,
intermediate layer 202 may be suspended between inner layer 205 and
outer layer 204 via coupling to both layers 204, 205 at alternate
fixation sites 203a, 203b, 203c. In use, when helmet 201 is exposed
to a primarily tangential impact, this impact induces relative
translation between outer layer 204 and inner layer 205,
accommodated by in-plane compression 206 and tension 207 (e.g.,
expansion) of intermediate layer 202.
[0028] In various embodiments, the suspension of intermediate layer
202 between inner layer 205 and outer layer 204 also may allow for
small amounts of translation of inner layer 205 perpendicular to
and away from outer layer 204. In various embodiments, this
increase in separation between outer layer 204 and inner layer 205
may accommodate tangential translation between outer and inner
layers 204, 205 in an ovoid, non-spherical shape of helmet 201.
Without being bound by theory, in various embodiments, a primary
benefit of translation between the outer and inner layers 204, 205
during impact may be mitigation of rotational head acceleration. In
some embodiments, an additional benefit may be that translation
distributes the impact over a larger segment of intermediate layer
202, which may increase absorption of the impact force component
perpendicular to the outer layer 204 by controlled crumpling of the
honeycomb of the intermediate layer 202 in a direction
perpendicular to the honeycomb elements. In some embodiments, a
surface of inner layer 205, outer layer 204, or intermediate layer
202 may include one or more indicators that show the amount of
translation 208 between the outer and inner layers 204, 205 in
response to an impact to estimate impact severity. For example,
such indicators may be comprised of graded color bands 209, 210
that circumscribe the periphery of the inside of outer layer 204,
whereby increased exposure of color bands 209, 210 indicates an
increased impact force.
[0029] In some embodiments, the intermediate layer may include two
or more layers of honeycomb materials having different stiffness,
such that the less stiff layers protect the brain during mild
impacts, and the stiffer layers protect the brain during severe
impacts. In other embodiments, the honeycomb cells may be entirely
or partially filled with an additional energy absorbing material,
such as an expanded foam. In particular embodiments, the additional
energy absorbing material may be of non-uniform thickness, and may
be configured, for example, such that the intermediate layer
becomes progressively stiffer as it is crushed in the direction
tangential to the outer layer, and/or in the direction
perpendicular to the outer layer. In still other embodiments, the
additional energy absorbing material also may form a solid layer on
the inner and/or outer surface of the honeycomb.
[0030] FIGS. 3A and 3B illustrate non-elastic, plastic deformation
of an example of a honeycomb layer, shown in non-deformed (FIG. 3A)
and deformed, partially cut-away (FIG. 3B) states, in accordance
with various embodiments. In various embodiments, an impact force
acting perpendicular to the outer helmet surface in excess of the
compressive strength of the honeycomb layer may induce plastic,
permanent compression of the honeycomb layer by means of crumpling
of honeycomb cells. In various embodiments, the plastic,
non-recoverable crumpling of honeycomb cells may absorb an impact
by depleting a portion of the impact force. Thus, this crumpling
may reduce or eliminate rebound after impact, which may otherwise
induce rotational head acceleration subsequent to a primary impact.
In some embodiments, in order to minimize an initial peak force
required to initiate crumpling, the honeycomb layer may be
pre-crushed to a certain degree, such as about 1-20% of its
thickness, or about 5-15% in various embodiments.
[0031] FIGS. 4A and 4B illustrate schematic drawings of a planar
portion (FIG. 4A) and a spherically shaped portion (FIG. 4B) of an
example honeycomb configuration that enables spherical,
three-dimensional shaping, in accordance with various embodiments.
In the illustrated example, this honeycomb configuration 404
enables conforming of an aluminum honeycomb into the spherical,
three-dimensional shape of a helmet, while retaining a
substantially symmetric shape of honeycomb elements without
buckling of honeycomb elements.
[0032] FIGS. 5A, 5B, and 5C depict a schematic drawing of a
honeycomb layer segment with alternate fixation points, shown in
unloaded (FIG. 5A) and loaded, deformed conditions (FIG. 5B), and a
perspective view of the honeycomb layer in loaded, deformed
condition (FIG. 5C), in accordance with various embodiments. FIG.
5A illustrates an example of a non-deformed honeycomb 502, with
some fixation sites 510 attached to an inner helmet layer, and
other fixation sites 511 attached to an outer helmet layer. In
various embodiments, honeycomb 502 may include void sections 512
for ventilation, which may correspond to similar void sections in
the inner and outer helmet layers. FIG. 5B illustrates honeycomb
502 under tangential loading, whereby honeycomb segments between
alternate fixation points 510 and 511 are deformed to accommodate
suspension and translation between the inner and outer helmet
layers. FIG. 5C illustrates again the deformed shape of honeycomb
502 due to tangential force introduction through fixation point
511.
[0033] In some embodiments, the alternate fixation sites between
the respective layers may include non-permanent connections, such
as hook-and-loop connections, and may allow for replacement of the
inner, outer, or intermediate layer if damaged. In other
embodiments, the inner layer may be attached to the outer layer
with an elastic material, and wherein the elastic material holds
the inner layer in place during normal wearing, but allows relative
displacement between the inner layer and outer layer in an
impact.
[0034] FIG. 6 illustrates an example of a helmet 601 having an
intermediate layer 602 in suspension between outer layer 604 and
inner layer 605, wherein intermediate layer 602 is coupled to the
inner and outer layers via alternate fixation sites 603. In the
illustrated embodiment, helmet 601 also includes a padding layer
608 on the inside of inner layer 605 to improve comfort and help
attenuate impacts. In various embodiments, padding layer 608 may
include a single layer or may be comprised of multiple sections. In
some embodiments, one or more glidable interface layers 607 may be
added between at least a part of intermediate layer 602 and outer
layer 604. In some embodiments, one or more glidable interface
layers 606 may be added between at least a part of intermediate
layer 602 and inner layer 605. In some embodiments, these interface
layers 606 and 607 may reduce friction to enhance tangential
displacement between the inner and outer layers during an oblique
impact. In addition, in some embodiments, inner layer 605 may be
configured with perforations or alternative means to reduce its
in-plane stiffness in order to enhance tangential displacement
between the inner and outer layer during an oblique impact. In
further embodiments, intermediate layer 602, and/or inner 605 layer
or outer 607 layer, may be provided with a colorimetric indicator
that indicates the severity of impact when the helmet sustains an
impact force. In some embodiments, the severity of impact may be
shown as the degree of displacement of the outer layer 607 relative
to the inner 605 and/or intermediate 602 layers.
[0035] FIG. 7 illustrates a cross-sectional mid-sagittal view of
another embodiment of a helmet 701 shown during impact in a loaded,
partially deformed configuration. In this embodiment, some or all
of the fixation points 703a, 703b, 703c are not rigid connections
(703b), but rather are unidirectional couplings 703a, 703c that
locally couple the layers together upon tangential forces in one
direction, while allowing free relative displacement upon
tangential forces in another direction. For example, in the
illustrated embodiment, relative translation between the outer
layer 704 and inner layer 705 is accompanied by in-plane
compression of the intermediate layer 702 on one side 706, but the
other side 707 remains undeformed in the in-plane direction. In the
illustrated embodiment, the inner layer 705 is held in place in the
undeformed configuration by elastic connections 708, and in various
embodiments, these elastic connections may allow for relative
displacement between the outer layer 704 and inner layer 705 in an
impact. In practice, this embodiment may allow for greater control
of the in-plane stiffness of the intermediate layer 701.
[0036] FIG. 8 illustrates a cross-sectional view of a section of
another embodiment, wherein the outer layer 801 and inner layer 802
are perforated with a multitude of holes 803, which may allow for
ventilation through the honeycomb cells in intermediate layer 804.
Although a particular hole size is illustrated, one of skill in the
art will appreciate that a range of hole sizes is contemplated, for
example, from about 1 mm to about 3 cm, such as about 0.5-2 cm, or
about 1 cm, depending on the application. The holes may be ordered
in an array or random in placement, and different portions of the
helmet may have holes of different sizes and/or placement,
depending on the ventilation needs of the particular application.
It will be appreciated that it may be advantageous to supply the
helmet with a multitude of small ventilation holes in order to
prevent the gaps in protection that may result from the larger
ventilation holes used in most conventional helmets. Additionally,
providing a multitude of small holes may enable the helmet to have
a more streamlined, smooth shape, which in turn may reduce the
chance that a helmet contour may "catch" on an obstacle or
obstruction during a fall or other head impact, which could
increase rotational impact forces.
[0037] Although certain embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a wide variety of alternate and/or equivalent
embodiments or implementations calculated to achieve the same
purposes may be substituted for the embodiments shown and described
without departing from the scope. Those with skill in the art will
readily appreciate that embodiments may be implemented in a very
wide variety of ways. This application is intended to cover any
adaptations or variations of the embodiments discussed herein.
Therefore, it is manifestly intended that embodiments be limited
only by the claims and the equivalents thereof.
* * * * *