Note: Descriptions are shown in the official language in which they were submitted.
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MULTI-SHELL HELMET WITH PIVOTABLE OUTER SHELL
Cross-Reference to Related Applications
[0001] This application claims priority from, and for the purposes of the
United States,
claims the benefit under 35 U.S.C. 119 of, US application No. 63/124678 filed
11
December 2020 and entitled MULTI-SHELL HELMET WITH PIVOTABLE OUTER SHELL
which is hereby incorporated herein by reference for all purposes.
Technical Field
[0002] The present invention relates to helmets and headwear. Particular non-
limiting
embodiments provide a multi-shell helmet with an inner member having a
concavity for
receiving at least a portion of the head of a user and an outer shell that is
pivotable relative
to the inner member and a method for using same to mitigate head and/or
cervical spine
injuries and/or fractures. Another embodiment provides a method for
converting/retrofitting a
single-shell helmet to a multi-shell helmet comprising an inner member having
a concavity
for receiving at least a portion of the head of a user and an outer shell that
is pivotable
relative to the inner member.
Background
[0003] Helmets and other protective headgear are used in a variety of contexts
and are
designed to protect a wearer's head from physical impact. A typical helmet has
an outer
shell and an inner protective liner. The outer shell provides the structural
rigidity of the
helmet and is often made of a solid material, e.g. plastic, fiberglass, carbon
fiber,
polycarbonate or similar composites. The outer shell also protects against
penetration of
sharp objects and distributes an impact force across the inner protective
liner. The inner
protective liner typically provides deformable foam to absorb impact/crash
energy so that
the acceleration experienced by the head is reduced, relative to that which
would be
experienced by the head in the absence of a helmet. The inner protective liner
may typically
be made of expanded polystyrene ("EPS"), expanded polypropylene ("EPP"), vinyl
nitrile ("VN")
or ethylene-vinyl acetate ("EVA"). Helmets with EPS liners are referred to as
single-impact
helmets because EPS permanently deforms upon impact. Helmets with EPP, VN or
EVA liners
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are referred to as multiple-impact helmets because such liners can recover and
return to their
initial shapes after impact. Generally speaking, the thicker the inner
protective liner is, the more
impact/crash energy it will be able to absorb. However, if the inner
protective liner is too thick,
the outer circumference and weight of the helmet are correspondingly large,
which may detract
from the appearance of the helmet and may contribute to strain on the neck.
[0004] Most designs of helmets and protective headgear offer limited
protection for the neck.
The neck is the uppermost portion of the vertebral column and located between
the head and
thorax. It has seven cervical vertebrae C1-C7 separated by intervertebral
discs except for the
top two vertebrae where it joins to the head. Inadequate neck protection may
lead to fracture
of the vertebrae and the fractured vertebrae may compress or impart
undesirable forces on the
spinal cord resulting in spinal cord injuries which can be medically
devastating events.
Specifically, axial compressive type neck injuries can cause a particularly
devastating type
of spinal cord injury resulting in quadriplegia. Alternate terms for an axial
compression injury
include a vertebral compression fracture, fracture-dislocation of the cervical
spine, axial
compression fracture, axial compression burst fracture, or an axial load
injury. Cervical
spine fractures at the Cl or C2 vertebrae are frequently fatal, and fracture-
dislocations at
the C3-C7 vertebrae frequently result in quadriplegia.
[0005] Axial compressive type neck injuries are most likely when the head and
the cervical
spine are aligned with the direction of an impact force as shown in Figure 1.
This alignment
occurs when the head is tilted about 30 downwardly relative to the torso and
towards the
neck, thereby removing the natural curvature of the cervical spine and
orienting the
vertebrae in a stacked orientation. When an impact force is oriented along the
aligned
cervical spine, it can cause compressive burst fractures and fracture
dislocations in the
spine.
[0006] There is a general desire for helmets and headwear that are comfortable
to wear
and can mitigate head and/or cervical spine fractures.
[0007] The foregoing examples of the related art and limitations related
thereto are intended
to be illustrative and not exclusive. Other limitations of the related art
will become apparent
to those of skill in the art upon a reading of the specification and a study
of the drawings.
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Summary
[0008] The following embodiments and aspects thereof are described and
illustrated in
conjunction with systems, tools and methods which are meant to be exemplary
and
illustrative, not limiting in scope. In various embodiments, one or more of
the above-
described problems have been reduced or eliminated, while other embodiments
are
directed to other improvements.
[0009] A pivot helmet is provided. The pivot helmet can be used to prevent or
mitigate
cervical spine fractures, including the type of injuries associated with
spinal axial
compression and fracture of the spine which may otherwise result in
deformation and/or
injury to the spinal cord. The pivot helmet is configured to convert an impact
force with
component aligned with the axis of the spine (an "axial component") to
rotational (or pivotal)
motion. In the event of a head-first impact, the pivot helmet induces flexion
of the neck so
that the head and the cervical spine are not aligned with the direction of an
impact force,
thereby mitigating the likelihood and/or severity of cervical spine fractures.
[0010] One aspect relates to a multi-shell helmet. The helmet comprises an
outer shell
defining a concavity; an inner member, at least a portion of which is located
within the
concavity, the inner member pivotally coupled to the outer shell and permitted
to move
relative to the outer shell by rotation about a laterally oriented pivot axis.
The helmet
comprises a deployment device which, in the absence of sufficient external
force, constrains
rotational motion between the inner member and the outer shell about the pivot
axis (e.g. to
within a minimum rotational amount). That is, in the absence of sufficient
external force, the
deployment device constrains the initial relative angular orientations of the
inner member
and the outer shell about the pivot axis (e.g. to within minimum relative
angular
orientations). The deployment device may constrain the relative motion between
the inner
member and the outer shell by applying force between the inner member and the
outer shell
(or between any components of the pivotal coupling between the inner member
and the
outer shell) that tends to prevent relative rotation. When the helmet receives
an impact
having sufficient force (e.g. an external force greater than a threshold), the
deployment
device deploys to permit relative angular rotation between the outer shell and
the inner
member about the pivot axis. In some embodiments, the deployment device may be
in an
initial configuration in the absence of sufficient external force and a
deployment
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configuration (different from the initial configuration) when the helmet
receives an impact
having sufficient force.
[0011] The location of the laterally oriented pivot axis can impact the motion
path
(kinematics) of a wearer's head and neck, and this motion can affect the
mechanical loads
(kinetics) acting on the head and neck. In some embodiments, the laterally
oriented pivot
axis is parallel to a coronal plane and orthogonal to a mid-sagittal plane of
the helmet. The
laterally oriented pivot axis passes a coupling zone bounded by three notional
lines in the
mid-sagittal plane of the helmet, the three lines being: a center of gravity
line; a brow line
running from a front portion to a back portion of the helmet and tangential to
a lowermost
point on a surface that defines a top edge of a face opening; and an anterior
line parallel to
the center of gravity line and intersecting the lowermost point of the top
edge surface of the
face opening.
[0012] In some embodiments, pivot joint and the deployment device may be
separate from
each other. In some other embodiments, the pivot joint and the deployment
device may be
integrated into one mechanism.
[0013] The pivot joint may comprise two pivot mechanisms located
symmetrically on the
helmet.
[0014] One or both of the two pivot mechanisms may be positioned between a
center of
gravity line of the helmet and a position where a maximal relative angular
rotation range
between the inner member and the outer shell after deployment of the
deployment device is
in a range of 10 -30 .
[0015] One or both of the two pivot mechanisms may be positioned such that a
position that
the laterally oriented pivot axis intersects the sagittal plane is at a
midpoint between an arc
center of the inner member and an arc center of the outer shell.
[0016] A first pivot mechanism may pivot around a first pivot axis and a
second pivot
mechanism may pivot around a second pivot axis.
[0017] The first pivot axis and the second pivot axis may and the laterally
oriented pivot axis
may be collinear.
[0018] One or both of the two pivot mechanisms may provide three degrees of
rotational
freedom.
[0019] The translational positions of the first and second axes may be fixed.
[0020] The orientation of at least one of the first and second pivot axes may
be variable.
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[0021] One or both of the pivot mechanisms may comprise a surface bearing
pivot joint.
Two complementary surfaces may bear against one another to provide the
movement of the
surface bearing pivot joint.
[0022] One or both of the pivot mechanisms may comprise one or more ball-
socket pivot
joints.
[0023] One or both of the pivot mechanisms may comprise one or more full-
socket type
pivot joints.
[0024] One or both of the pivot mechanisms may comprise one or more half-
socket type
pivot joints.
[0025] One or both of the pivot mechanisms may comprise one or more tapered
components that are mounted to one of the inner member and the outer shell.
[0026] The outer shell may be shaped to induce torque on the outer shell
(relative to the
inner shell) by interaction between the outer shell and the ground (or other
impact surface)
to thereby cause the inner shell to rotate relative to the outer shell about
the pivot axis. For
example, helmets suitable for sports that involve low-friction impact surfaces
such as ice
and/or snow and/or for other applications involving pivotable helmets, the
outer shell may
be shaped to provide one or more extremities/apexes such that interaction
between the
outer shell and the ground (or other impact surface) induces torque on the
outer shell. In
some embodiments or applications, it may be desirable to provide a number
(e.g. one or
more) of extremities/apexes on the outer surface of the outer shell (e.g. at
the intersection
of the outer surface of the outer shell with the mid-sagittal plane).
[0027] Another aspect relates to a helmet that may comprise an outer shell
defining a
concavity, an inner member. At least a portion of the inner member may be
located within
the concavity. The helmet may further comprise first and second pivot joints
located on
opposing sides of the inner member which may facilitate relative pivotal
movement between
the inner member and the outer shell. The first pivot joints may permit
rotation about
corresponding first and second pivot axes. The first and second pivot joints
may permit
orientations of the first and second pivot axes to change while maintaining
translational
positions of the first and second pivot axes static.
[0028] Another aspect relates to a helmet that may comprise an outer shell
defining a
concavity and an inner member, at least a portion of which is located within
the concavity.
The helmet may further comprise first and second pivot joints located on
opposing sides of
the inner member which may facilitate relative pivotal movement between the
inner member
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and the outer shell. The first pivot joints may permit rotation in three
degrees of freedom
and maintain static translation positions.
[0029] Another aspect relates to a method for mitigating cervical spine
injuries and/or
fractures. The method comprises providing a multi-shell helmet. The helmet
comprises an
outer shell defining a concavity; an inner member, at least a portion of which
is located
within the concavity, the inner member pivotally coupled to the outer shell
and permitted to
move relative to the outer shell by rotation about a laterally oriented pivot
axis. The helmet
comprises a deployment device which, in the absence of sufficient external
force, constrains
rotational motion between the inner member and the outer shell about the pivot
axis (e.g. to
within a minimum rotational amount). That is, in the absence of sufficient
external force, the
deployment device constrains the initial relative angular orientations of the
inner member
and the outer shell about the pivot axis (e.g. to within minimum relative
angular
orientations). The deployment device may constrain the relative motion between
the inner
member and the outer shell by applying force between the inner member and the
outer shell
(or between any components of the pivotal coupling between the inner member
and the
outer shell) that tends to prevent relative rotation. When the helmet receives
an impact
having sufficient force (e.g. an external force greater than a threshold), the
deployment
device deploys to permit relative angular rotation between the outer shell and
the inner
member about the pivot axis. In some embodiments, the deployment device may be
in an
initial configuration in the absence of sufficient external force and a
deployment
configuration (different from the initial configuration) when the helmet
receives an impact
having sufficient force.
[0030] Another aspect relates to a method for retrofitting a single-shell
helmet to a multi-
shell helmet. The method comprises determining a coupling zone, the coupling
zone being
bounded by three notional lines in a mid-sagittal plane of the single-shell
helmet, the three
lines being: a center of gravity line; a brow line running from a front
portion to a back portion
of the helmet and tangential to a lowermost point on a surface that defines a
top edge of a
face opening; and an anterior line parallel to the center of gravity line and
intersecting the
lowermost point of the top edge surface of the face opening. At least a
portion of a second
shell is positioned within a concavity of the first shell. The second shell
and the first shell are
pivotably coupled together by a pivot joint having a laterally oriented pivot
axis that
intersects the mid-sagittal plane in the coupling zone, so that the second
shell and the first
shell are movable relative to one another by rotation about the laterally
oriented pivot axis,
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wherein the laterally oriented pivot axis is parallel to a coronal plane and
orthogonal to a
mid-sagittal plane of the helmet. The helmet comprises a deployment device
which, in the
absence of sufficient external force, constrains rotational motion between the
inner member
and the outer shell about the pivot axis (e.g. to within a minimum rotational
amount). That is,
in the absence of sufficient external force, the deployment device constrains
the initial
relative angular orientations of the inner member and the outer shell about
the pivot axis
(e.g. to within minimum relative angular orientations). The deployment device
may constrain
the relative motion between the inner member and the outer shell by applying
force
between the inner member and the outer shell (or between any components of the
pivotal
coupling between the inner member and the outer shell) that tends to prevent
relative
rotation. When the helmet receives an impact having sufficient force (e.g. an
external force
greater than a threshold), the deployment device deploys to permit relative
angular rotation
between the outer shell and the inner member about the pivot axis. In some
embodiments,
the deployment device may be in an initial configuration in the absence of
sufficient external
force and a deployment configuration (different from the initial
configuration) when the
helmet receives an impact having sufficient force.
[0031] In addition to the exemplary aspects and embodiments described above,
further
aspects and embodiments will become apparent by reference to the drawings and
by study
of the following detailed descriptions.
Brief Description of the Drawings
[0032] Exemplary embodiments are illustrated in referenced figures of the
drawings. It is
intended that the embodiments and figures disclosed herein are to be
considered illustrative
rather than restrictive.
[0033] Figure 1 shows a photograph of a skeleton where the skeleton is
positioned so that
the head and the cervical spine are aligned with the direction of an impact
force.
[0034] Figure 2 schematically shows a process enabled by a helmet according to
one
embodiment of the present invention to induce flexion of the neck when the
helmet receives
a head-first impact resulting in axial loading on the cervical spine.
[0035] Figure 3 shows a perspective view of the head of a wearer, wherein the
head is
situated in an anatomical coordinate system to illustrate certain directional
features.
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[0036] Figure 4 shows a cross-sectional view of a helmet according to one
embodiment of
the present invention, wherein the helmet is worn on a head.
[0037] Figure 5 shows a front view of the Figure 4 helmet.
[0038] Figure 6 shows an enlarged and partial view of the Figure 5 helmet.
[0039] Figure 7 shows a cross-sectional view of the Figure 4 helmet taken
along its notional
mid-sagittal plane, wherein the helmet is not worn on a head.
[0040] Figures 8A and 8B show cross-sectional views of the Figure 4 helmet
upon impact
and post impact, respectively.
[0041] Figure 9 shows the effect of pivot joint location (i.e. the location of
a laterally oriented
pivot axis) on the range of rotational motion of an outer shell about the
pivot joint between
an inner shell and the outer shell of the Figure 4 helmet.
[0042] Figure 10 shows how torque is created on the head and an inner member
(e.g. on
the pivot joint) of the Figure 4 helmet as a result of misaligned forces.
[0043] Figure 11 shows that the mass moment of inertia can be impacted by the
distance
between the pivot location (i.e. the location of a laterally oriented pivot
axis) and the center
of gravity of a wearer's head.
[0044] Figure 12 shows a cross-sectional (mid-sagittal plane) view of a helmet
according to
another embodiment of the present invention, wherein the helmet is worn on a
head.
[0045] Figure 13 shows a cross-sectional (mid-sagittal plane) view of the
Figure 12 helmet
receiving an impact force from a high-friction surface.
[0046] Figures 14A, 14B, and 14C show cross-sectional (mid-sagittal plane)
views of the
Figure 12 helmet receiving an impact force from a low-friction surface.
[0047] Figure 15 shows how torque is created on the inner shell and head which
will result
in rotational motion of the inner shell and head.
[0048] Figure 16 shows a flow diagram of an example embodiment of a method for
converting/retrofitting a single-shell helmet to a multi-shell helmet.
[0049] Figure 17A shows a perspective view of a portion of a multi-shell
helmet that has
been retrofitted from a single-impact, single-shell helmet according to a
particular
embodiment.
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[0050] Figure 17B shows a perspective view of a multi-shell helmet that has
been retrofitted
from a multiple-impact, single-shell helmet according to a particular
embodiment.
[0051] Figure 18 shows a perspective view of a multi-shell helmet that has
been retrofitted
from a single-shell helmet according to a particular embodiment.
[0052] Figure 19A shows a schematic perspective view of the Figure 4 helmet.
Figure 19B
shows a schematic cross-sectional view of the Figure 4 helmet. Figures 19A and
19B better
illustrate the structural features of the Figure 4 helmet's pivot joint and a
deployment device
according to a particular embodiment.
[0053] Figure 20A shows a schematic perspective view of an example helmet.
Figure 20B
shows a schematic cross-sectional view of the Figure 20A helmet. Figures 20A
and 20B
illustrate the structural features of a pivot joint and a deployment device
according to
particular embodiment.
[0054] Figure 21A shows a partial schematic perspective view of an example
helmet. Figure
21B shows a partial schematic cross-sectional view of the Figure 21A helmet.
Figures 21A
and 21B illustrate the structural features of a pivot joint having a built-in
deployment device
according to a particular embodiment.
[0055] Figure 22A shows a partial schematic perspective view of an example
helmet
comprising a pivot joint having a built-in deployment device according to a
particular
embodiment, wherein the pivot joint has a female component and a male
component.
Figure 22B shows a partial schematic perspective view of the female component
shown in
Figure 22A. Figure 22C shows a partial schematic perspective view of the male
component
shown in Figure 22A.
[0056] Figure 23A shows a partial schematic perspective view of an example
helmet
comprising a pivot joint having a built-in deployment device according to a
particular
embodiment, wherein the pivot joint has a female component and a male
component.
Figure 23B shows a partial schematic perspective view of the male component
shown in
Figure 23A. Figure 23C shows a partial schematic perspective view of the
female
component shown in Figure 23A.
[0057] Figure 24A shows a schematic partial perspective view of an example
helmet
comprising a pivot joint having a built-in deployment device according to a
particular
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embodiment, wherein the pivot joint has a female component and a male
component.
Figure 24B shows a partial schematic perspective view of the female component
shown in
Figure 24A. Figure 24C shows a partial schematic perspective view of the male
component
shown in Figure 24A.
[0058] Figure 25 shows a schematic depiction of the different layers in an
example helmet.
[0059] Figure 26 shows a schematic depiction of the different layers in an
example helmet.
[0060] Figures 27A, 27B show schematic depictions of selecting a y-coordinate
of pivot
placements in example embodiment embodiments.
[0061] Figure 28A shows a perspective view of an example assembled full-socket
type pivot
joint. Figure 28B shows a perspective view of an example component of the
example full-
socket type pivot joint of Figure 28A. Figure 28C shows a perspective view of
an example
component of the example full-socket type pivot joint of Figure 28A.
[0062] Figure 29A shows a perspective view of an example assembled half-socket
type ball
joint. Figure 29B shows a perspective view of an example component of the
example half-
.. socket type ball joint of Figure 29A. Figure 29C shows a perspective view
of an example
component of the example half-socket type ball joint of Figure 29A.
[0063] Figure 30 shows a perspective view of an example pivot joint.
[0064] Figure 31 shows a perspective view of an example pivot joint.
[0065] Figure 32 shows a schematic depiction of an example coupling between an
example
pivot joint and outer-shell.
[0066] Figure 33A shows a perspective view of a second end of an example pivot
joint.
Figure 33B shows a side view of the example pivot joint of Figure 33A.
[0067] Figure 34 shows a schematic depiction of an example coupling between an
example
pivot joint and outer-shell.
[0068] Figure 35 shows a schematic depiction of an example coupling between an
example
pivot joint and outer-shell.
[0069] Figure 36 shows a schematic depiction of an example coupling between an
example
pivot joint and outer-shell.
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Description
[0001] Throughout the following description specific details are set forth in
order to provide
a more thorough understanding to persons skilled in the art. However, well
known elements
may not have been shown or described in detail to avoid unnecessarily
obscuring the
disclosure. Accordingly, the description and drawings are to be regarded in an
illustrative,
rather than a restrictive, sense.
[0002] Aspects of the present invention can be used to prevent or mitigate
cervical spine
fractures, including the type of injuries associated with axial compression of
the spine and
fracture of the spine which may otherwise result in deformation and/or injury
to the spinal
cord. Aspects of the present invention convert an impact force with a
component aligned
with the axis of the spine (a "spinally axial component") to rotational
motion. In the event of
a head-first impact, the present invention induces flexion of the neck so that
the head and
the cervical spine are not aligned (or less aligned) with the direction of an
impact force,
thereby mitigating the likelihood and/or severity of cervical spine fractures.
[0003] A number of aspects of the present invention will be described below
and include:
= a helmet comprising an inner member having a concavity for receiving at
least a
portion of the head of a user and an outer shell that is pivotable relative to
the inner
member;
= a method for using a multi-shell helmet with an inner member and outer
shell that is
pivotable relative to the inner member to reduce the severity of and/or
mitigate head
and/or cervical spine fractures; and
= a method for converting/retrofitting a single-shell helmet to a multi-
shell helmet with
an outer shell that is pivotable relative to an inner member.
[0004] For each aspect, one or more embodiments may be described.
First Aspect ¨ Helmet with Outer Shell Pivotable Relative to Inner Member
[0005] A first aspect of the present invention provides a helmet comprising an
inner
member 106 having a concavity for receiving at least a portion of the head of
a user and an
outer shell 104 that is pivotable relative to inner member 106. As
schematically shown in
Figure 2, the helmet enables rotation of inner member 106 (and corresponding
rotation of
the wearer's head) relative to outer shell 104 about a pivot axis 138, thereby
inducing
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flexion of the neck when the helmet receives a spinally axial impact or an
impact with a
spinally axial component. The flexion of the neck may mitigate cervical spine
fractures, as
this flexion re-orients the alignment of the head and the cervical spine
relative to the
direction of the impact force. Flexion of the neck may also keep the head
moving for a
longer duration (relative to the duration of head movement with a standard
helmet, where
the head stops abruptly due to its impact with another object and then the
aligned spine is
loaded by the still-moving torso). The specific location of the pivot axis 138
is an important
consideration for mitigation of cervical spine fractures.
[0075] The Figure 2 helmet comprises an outer shell 104 providing an outer
shell concavity
and an inner member 106 (which may also be shaped like a shell), at least a
portion of
which is located within the outer shell concavity. The inner member 106 is
also shaped to
provide an inner shell concavity for receiving the head of a wearer. The outer
shell 104 and
the inner member 106 are connected to one another for relative pivotal motion
about a
laterally oriented pivot axis 138. The outer shell 104 and the inner member
106 may be
connected by any suitable pivot joint(s) 108 that facilitate relative rotation
about the laterally
oriented pivot axis 138.
[0076] The helmet comprises a deployment device which, in the absence of
sufficient
external force, constrains rotational motion between the inner member 106 and
the outer
shell 104 about the pivot axis 138 (e.g. to within a minimum rotational
amount). That is, in
the absence of sufficient external force, the deployment device constrains the
initial relative
angular orientations of the inner member 106 and the outer shell 104 about the
pivot axis
138 (e.g. to within minimum relative angular orientations). In some
embodiments, this
minimum relative rotation is less than 5 . In some embodiments, this minimum
relative
rotation is less than 2.5 . In some embodiments, this minimum relative
rotation is less than
1.25 . The deployment device may constrain the relative motion between the
inner member
106 and the outer shell 104 by applying force between the inner member 106 and
the outer
shell 104 (or between any components of the pivotal coupling 108 between the
inner
member 106 and the outer shell 104) that tends to prevent relative rotation.
When the
helmet receives an impact having sufficient force (e.g. an external force
greater than a
threshold), the deployment device deploys to permit relative angular rotation
between the
outer shell 106 and the inner member 104 about the pivot axis 138. In some
embodiments,
the deployment device permits a larger range of motion (between outer shell
104 and inner
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member 106 about pivot axis 138) upon receiving an impact force (as compared
to the
absence of an impact force). In some embodiments, this larger range of
permissible relative
rotation is greater than 50. In some embodiments, this larger range of
permissible relative
rotation is greater than 100. In some embodiments, this larger range of
permissible relative
rotation is greater than 15 . In some embodiments, the deployment device may
be in an
initial configuration in the absence of sufficient external force and a
deployment
configuration (different from the initial configuration) when the helmet
receives an impact
having sufficient force.
[0077] The deployment device performs several functions. For example, the
deployment
device provides helmet stability by maintaining an initial relative angular
relationship
between the inner member 106 and the outer shell 104 about the pivot axis 138.
A good
helmet fit can be achieved because, in the absence of an impact, the outer
shell 104 will not
rotate relative to the inner member 106. Also, the deployment device may
function to permit
sufficient frictional force to build up when the helmet receives an impact.
This frictional force
may then help to induce rotation between the inner member 106 and the outer
shell 104
and change the direction of the head's momentum. In response to an impact
force (e.g. an
axial force that may be (or may have a component) parallel to the spinal
axis), the multi-
shell helmet may induce flexion of the neck and thereby mitigate cervical
spine fractures.
[0078] As used herein, unless the context dictates otherwise, the expressions
"axial loading
in the spine", "spinally axial force", and "spinally axial impact force" mean
an impact force
with a component aligned with the axis of the cervical portion of the spine,
when such
cervical portion is generally aligned. Similarly, unless the context dictates
otherwise, a
"spinally axial component" means a component of an impact force aligned with
the axis of
the cervical portion of the spine, when such cervical portion is generally
aligned.
[0079] As used herein, unless the context dictates otherwise, the terms
"rotation angle"
and/or "angle of rotation" mean the angle that an inner member and an outer
shell are able
to rotate (or have rotated) relative to one another or relative to their
initial angular position
about a laterally oriented pivot axis.
(a) A First Helmet Embodiment
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[0080] Figures 4, 5 and 7 show a helmet 100 according to an example
embodiment. A
number of features of helmet 100 may be more easily explained relative to
notional features
of a wearer's head. Figure 3 illustrates a wearer's head 10 situated in an
anatomical
coordinate system. The wearer may wear helmet 100 (or any of the other helmet
described
herein) by inserting their head 10 into the helmet as described in more detail
below. The
corona! plane 12 divides head 10 into approximate front (anterior) and back
(posterior)
halves. The corona! plane 12 passes the left and right tragions, located at
the notch just
above the tragus of the left and right ear. The mid-sagittal plane 14 divides
head 10 into
approximate left and right halves. The corona! plane 12 and the mid-sagittal
plane 14
intersect at a notional central line 16, which is vertical in the Figure 3
view, but which may
generally have any orientation which depends on the orientation of head 10.
[0081] Head 10 comprises a frontal region 18, a left side region 20, a right
side region 22,
an occipital region 24, and a crown region 26. Frontal region 18 corresponds
substantially to
the frontal bone region of head 10. Left and right side regions 20, 22 are
located above the
left and right ears of the wearer. Occipital region 24 and crown region 26
correspond
substantially to the back and top of head 10.
[0082] Referring to Figures 4, 5 and 7, helmet 100 (in particular inner member
106) defines
a head-receiving concavity 115 that conforms generally to head 10. Helmet 100
defines
several notional lines, including a brow line 112, an anterior line 114, and a
center of gravity
("COG") line 102. These notional lines are located in a notional mid-sagittal
plane 120 of
helmet 100 and are shown schematically in Figure. 7, which is a cross-
sectional view of
helmet 100 taken at the notional mid-sagittal plane 120. The notional mid-
sagittal plane 120
of helmet 100 is defined relative to head 10. When helmet 100 is worn on head
10, the
notional mid-sagittal plane 120 of helmet 100 is roughly co-planar with mid-
sagittal plane 14
of head 10. Similarly, helmet 100 has a notional lateral plane (not shown) and
when helmet
100 is worn on head 10, the notional lateral plane of helmet 100 is roughly co-
planar with
corona! plane 12 of head 10. The notional mid-sagittal plane 120 intersects
with the notional
lateral plane at COG line 102. COG line 102 is generally parallel to or aligns
generally with
central line 16 of head 10 (Figure 3) when helmet 100 is worn on head 10. The
location of
COG line 102 may be specified by a helmet manufacturer, especially if the
manufacturer
uses the standardized Anthropomorphic Test Devices ("ATDs"), commonly referred
to as
crash test dummies, to design the dimensions and shapes of the helmets. An ATD
typically
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has head and neck dimensions that correspond to a 50th percentile of a sex-
and age-
specific population. If the location of COG line 102 is not specified by a
helmet
manufacturer, the approximate location of COG line 102 may be determined using
anatomical references to head 10 and/or to an ATD, such as the most posterior
portion of
the head and/or the eye socket and/or the ear canal. In some embodiments, the
approximate location of COG line 102 may be determined by using an ATD as
reference. In
some embodiments, COG line 102 and the center of curvature of inner member 106
or
outer shell 104 are both located in the notional mid-sagittal plane 120. In
some
embodiments, COG line 102 may pass through the centre of curvature of inner
member 106
and/or outer shell 104. COG line 102 may be substantially vertically oriented
(e.g. within
50) when helmet 100 is properly worn and the wearer is standing upright with
their neck at
a neutral position.
[0083] COG line 102 is named as such because when helmet 100 is worn on head
10, the
center of gravity of head 10 is located at least approximately on COG line
102. The center
of gravity of helmet 100 may also be located on COG line 102, but this may not
always be
the case. The location of the center of gravity of helmet 100 depends on the
specific design
of a helmet.
[0084] Brow line 112 is located in mid-sagittal plane 120 of helmet 100. Brow
line 112 runs
from a front portion to a back portion of helmet 100 and is tangential to a
surface 116 of
helmet 100 that defines a top edge of a face opening 119 at the lowermost
point of this
surface 116. When helmet 100 is worn on head 10, brow line 112 runs from an
anterior
aspect of the frontal bone to the occipital region.
[0085] Anterior line 114 is located in mid-sagittal plane 120 of helmet 100.
Anterior line 114
is parallel to COG line 102 and intersects the lowermost point of top edge
surface 116 of
face opening 119.
[0086] Structurally, helmet 100 comprises an outer shell 104 shaped to provide
an outer
concavity 105 and an inner member 106 which is at least partially located in
outer concavity
105 and is shaped to receive an inner head-receiving concavity 115. Outer
shell 104 and
inner member 106 are pivotably connected and are permitted to pivot relative
to one
another by rotation about a laterally oriented pivot axis 138. In the
illustrated embodiment,
outer shell 104 and inner member 106 are connected by a pair of pivot joints
108 located
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and aligned to facilitate rotation about pivot axis 138. Helmet 100 also
comprises a
deployment device 124 (described in more detail below) which, in the absence
of sufficient
external force, constrains rotational motion between inner member 106 and
outer shell 104
about pivot axis 138 (e.g. to within a minimum rotational amount). That is, in
the absence of
sufficient external force, deployment device 124 constrains the initial
relative angular
orientations of inner member 106 and outer shell 104 about pivot axis 138
(e.g. to within
minimum relative angular orientations). In some embodiments, this minimum
relative
rotation is less than 5 . In some embodiments, this minimum relative rotation
is less than
2.5 . In some embodiments, this minimum relative rotation is less than 1.25 .
Deployment
device 124 may constrain the relative motion between inner member 106 and
outer shell
104 by applying force between inner member 106 and outer shell 104 (or between
any
components of the pivotal coupling between inner member 106 and outer shell
104) that
tends to prevent relative rotation. When the helmet 100 receives an impact
having sufficient
force (e.g. an external force greater than a threshold), deployment device 124
deploys to
permit relative angular rotation between outer shell 104 and inner member 106
about pivot
axis 138 (see e.g. Figure 8A for the position of inner member 106 relative to
outer shell 104
pre external force and Figure 8B for the position of inner member 106 relative
to outer shell
104 after external force). In some embodiments, deployment device 124 permits
a larger
range of motion (between outer shell 104 and inner member 106 about pivot axis
138) upon
receiving an impact force (as compared to the absence of an impact force). In
some
embodiments, this larger range of permissible relative rotation is greater
than 5 larger than
a range of motion in the absence of impact force. In some embodiments, this
larger range of
permissible relative rotation is greater than 10 larger than a range of
motion in the absence
of impact force. In some embodiments, this larger range of permissible
relative rotation is
greater than 15 larger than a range of motion in the absence of impact force.
In some
embodiments, deployment device 124 may be in an initial configuration in the
absence of
sufficient external force and a deployment configuration (different from the
initial
configuration) when helmet 100 receives an impact having sufficient force.
[0087] Outer shell 104 is configured to provide the structural rigidity of
helmet 100 and to
protect against penetration of sharp objects. Outer shell 104 defines an outer
concavity 105.
When helmet 100 is worn on head 10, outer shell 104 is shaped to cover at
least one of
frontal region 18, crown region 26, and occipital region 24 of head 10. Outer
shell 104 may
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be made of any suitable solid, rigid materials, including plastic (including
fiber reinforced
plastics), fiberglass, carbon fiber (including a variety of different carbon
fibers such as
carbon fiber pre-preg and/or carbon fibers with various fabrics, tows and/or
weaves), bulk
moulding compounds polycarbonate, similar composites and/or the like. In some
.. embodiments, outer shell 104 may have a cross-sectional thickness on the
order of 35mm,
30mm, 25mm, 20mm, 15mm, lOmm, 5mm or less, for example.
[0088] Inner member 106 is located either entirely or partially within outer
concavity 105 of
outer shell 104. In some embodiments, inner member 106 comprises more than one
component, and each component may be pivotably coupled to outer shell 104.
Inner
member 106 may be made of any suitable material, including plastic (including
fiber
reinforced plastics), fiberglass, carbon fiber (including a variety of
different carbon fibers
such as carbon fiber pre-preg and/or carbon fibers with various fabrics, tows
and/or
weaves), bulk moulding compounds, polycarbonate, EPS, EPP, EVA, VN,
combinations of
these materials and/or the like. In some embodiments, inner member 106 may
comprise a
partial or full coverage scaffold EPS layer, where scaffold EPS is positioned
between one or
more elements of inner member 106 and head 10 when helmet 100 is worn. In some
embodiments, inner member 106 may comprise full coverage EPS. Inner member 106
may
comprise one or more holes. Such holes may advantageously aid in the
ventilation of helmet
100. In some embodiments, inner member 106 may comprise a plurality of layers.
In some
embodiments, inner member 106 may have a cross-sectional thickness on the
order of
35mm, 30mm, 25mm, 20mm, 15mm, lOmm or less, for example. In some embodiments
inner member 106 may have a cross-sectional thickness of 1mm to 5mm. In some
embodiments inner member 106 may have a cross-sectional thickness of 2mm to
3mm.
Inner member 106 and outer shell 104 may be made of the same material or
different
materials. Inner member 106 and outer shell 104 may have the same cross-
sectional
thickness or different cross-sectional thicknesses.
[0089] In some embodiments inner member 106 may comprise a shell made up of
one or
both of carbon fiber and fiberglass and an EPS layer. The EPS layer may be
situated within
a concavity of the shell. The EPS layer may be in contact with head 10 when
worn by a
wearer.
[0090] As shown in Figures 4 and 5, inner member 106 and outer shell 104 may
be
separated by a motion zone 142 that is between the outer surface 106A of inner
member
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106 and the inner (cavity-defining) surface 104A of outer shell 104. The
larger motion zone
142 is, the more physical space there is for outer shell 104 to rotate
relative to inner
member 106 (i.e. until the outer surface 106A of inner member 106 contacts the
inner
(cavity-defining) surface 104A of outer shell 104).
.. [0091] Motion zone 142 (which may be defined by the outer surface 106A of
inner member
106 and the inner surface 104A of outer shell 104) may have any suitable
shapes and/or
dimensions. In some embodiments, motion zone 142 has a uniform cross-sectional
thickness over at least a portion of motion zone 142, i.e. inner surface 104A
of outer shell
104 and outer surface 106A of inner member 106 are separated by a uniform
motion
distance 140 over at least a portion of motion zone 142. Motion distance 140
may be equal
to 1cm to 3cm over at least a portion of motion zone 142. For example, motion
distance 140
may be about 2.5cm over at least a portion of motion zone 142. In other
embodiments,
motion zone 142 has varying thickness, i.e. motion distance 140 varies
throughout motion
zone 142.
.. [0092] The shape and dimension of motion zone 142 may depend on (i) the
shapes of inner
surface 104A of outer shell 104 and outer surface 106A of inner member 106
(ii) motion
distance 140 (iii) the impact stiffness of one or both of outer shell 104 and
inner member
106 and (iv) the deformation properties of one or both of outer shell 104 and
inner member
106. Inner member 106 and outer shell 104 may experience the same or different
.. deformation in the event of the application of force. The deformation of
inner member 106
and/or outer shell 104 may be a result of one or more of the geometry,
thickness and
material properties of inner member 106 and/or outer shell 104. For example,
varying one
or both of the thickness and geometry of inner member 106 and/or outer shell
104 may vary
the stiffness of inner member 106 and/or outer shell 104. Increasing the
thickness of inner
.. member 106 and/or outer shell 104 may increase the stiffness of inner
member 106 and/or
outer shell 104. Geometric smoothing of the surface topology of inner member
106 and/or
outer shell 104 may increase the stiffness of inner member 106 and/or outer
shell 104. An
increase in stiffness may allow inner member 106 and/or outer shell 104 to
resist more
force. Different materials may have varying abilities to resist deformation in
part due to how
different materials perform when force is applied. A single material may have
varying
abilities to resist deformation when loads are applied in one or more
differing directions. In
some embodiments it may be desirable for the one or more materials that make
up one or
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both of inner member 106 and outer shell 104 to have a sufficient stiffness to
prevent one or
both of outer shell 104 and inner member 106 from deforming so much that a
collision
between the outer and inner shell impedes rotation.
[0093] Motion zone 142 may impact the angular range of relative rotation
between inner
member 106 and outer shell 104 about pivot axis 138. For example, motion zone
142 may
only permit inner member 106 to rotate in a first angular direction (relative
to outer shell 104
about pivot axis 138) to a first angular range maximum and may only permit
inner member
106 to rotate in a second angular direction (opposite the first angular
direction) to a second
angular range maximum. In some embodiments, motion zone 142 may permit
unlimited
relative rotational movement between inner member 106 and outer shell 104
about pivot
axis 138 in one or both angular directions.
[0094] In some embodiments, a cushioning material (e.g. a crushable or
plastically
deformable material) and/or fluid material (e.g. one or more of air, oil,
lubricant, gel, etc.) is
located in motion zone 142. Such material may be used to dampen rotational
acceleration
and/or velocity and/or may reduce the energy imparted to the head of the
wearer.
[0095] Figure 25 depicts a schematic of example layers that make up helmet 100
according
to a particular embodiment. As depicted, helmet 100 comprises outer shell 104
then motion
zone 142. Motion zone 142 is followed by inner member 106. Inner member 106
comprises
inner shell 111, EPS layer 107 and comfort foam layer 109. In the illustrated
embodiments,
inner shell 111 is adjacent to motion zone 142. In the illustrated embodiment,
EPS layer 107
is located between inner shell 111 and comfort foam layer 109. In the
illustrated
embodiment, comfort foam layer 109 may be in contact with head 10. Figure 26
depicts a
schematic of the example layers depicted within Figure 25 in the context a
helmet 100 on
head 10.
[0096] Inner member 106 and outer shell 104 are pivotably coupled together so
that inner
member 106 can rotate relative to outer shell 104 (or vice versa) about pivot
axis 138. Pivot
axis 138 is generally parallel to the lateral plane and orthogonal to mid-
sagittal plane 120 of
helmet 100.
[0097] The location of pivot axis 138 can impact both the motion path
(kinematics) of head
10 and the neck of the wearer of helmet 100, and this motion can affect the
mechanical
loads (kinetics) acting on head 10 and the neck of the wearer of helmet 100.
For example,
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the location of pivot axis 138 can impact the moment which is created by the
relative pivotal
movement of inner member 106 and outer shell 104 to change the direction of
momentum
of head 10 upon impact. The optimization strategy when selecting the location
of pivot axis
138 to facilitate rotational motion of head 10 and the neck of the wearer may
comprise
.. (without limitation): (i) maximizing (or providing at or above an
acceptable threshold level),
the available space for relative pivotal movement between outer shell 104 and
inner
member 106 so that, for example, the relative angular rotation range is
maximized;
(ii) increasing applied torque on the head and neck; (iii) decreasing the mass
moment of
inertia of the head and neck that the applied torque needs to overcome; and
(iv) minimizing
or reducing the probability of traumatic brain injury (which may be achieved
by reducing one
or both of the rotational velocity and rotational acceleration) while having
enough velocity to
protect the neck of the wearer.
[0098] To maximize available space for rotation, the location of pivot axis
138 may be
placed as close as possible to the centers of curvature of inner member 106
(e.g. outer
surface 106A) and outer shell 104 (e.g. inner surface 104A) to prevent the two
from colliding
with one another prematurely. Figure 9 illustrates that as pivot axis 138 is
moved further
away from the centers of curvature of inner member 106 and outer shell 104,
inner member
106 and outer shell 104 collide with each other after about 25 of relative
rotation. The
center of gravity 143 of the head is also shown in Figure 9 to illustrate that
pivot axis 138 is
positioned anterior to the center of gravity 143 and center of gravity line
102 (Figure7),
which intersects center of gravity 143. In some embodiments inner member 106
and outer
shell 104 may collide with each other after about 0 to 60 of relative
rotation depending on
the location of pivot axis 138 in relation to the centers of curvature of
inner member 106 and
outer shell 104.
[0099] To increase the applied torque between inner member 106 and outer shell
104 about
pivot axis 138, one option is to increase the distance (w) between COG line
102 and a
parallel line 145 that intersects pivot axis 138 on mid-sagittal plane 120.
Figure 10 illustrates
this point. The head-and-neck is encouraged to rotate by the applied torque,
T, which is
created by two forces: the downward (in the illustrated Figure 10 view) force
Fi from the
wearer's torso (not shown), which is oriented along COG line 102; and the
upward (in the
illustrated Figure 10 view) reaction force F2 at pivot axis 138, which is
oriented along line
145. These two forces, Fi, F2, create a torque Tthat is proportional to or at
least
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approximately proportional to the distance w between the lines 102, 145 along
which these
two forces Fi, F2 are oriented.
[0100] To decrease the mass moment of inertia, one option is to reduce the
distance (c/)
between a center of gravity 143 of head 10 and the location of pivot axis 138
on mid-sagittal
plane 120. Figure 11 illustrates this point. The mass moment of inertia
(Ipivot) of the head-
and-neck about pivot axis 138 stipulates how much the head-and-neck will
rotate due to the
applied torque T¨ a higher mass moment of inertia /pivot will reduce the
effect the torque T
will have on rotational motion (angular acceleration). The mass moment of
inertia 'pivot may
be estimated using the Parallel Axis Theorem below:
pivot =COG + Md2
iCOG = mass moment of inertia of head-and-neck about its COG 143
'pivot = mass moment of inertia of head-and-neck about pivot axis 138
m = mass of head-and-neck
d = distance between pivot axis 138 and COG 143
[0101] It may be desirable to have a large range of relative angular motion
between inner
member 106 and outer shell 104 and to create a small mass moment of inertia to
resist
changes to the magnitude of head rotational momentum. However, these two goals
may be
viewed as competing. The greatest range of rotational motion typically
involves locating
pivot axis 138 as close as possible to the intersection between brow line 112
and COG line
102. This would also minimize the mass moment of inertia. On the other hand,
to create the
largest moment possible that will change/offset the direction of head
momentum, it may be
desirable to locate pivot axis 138 as close as possible to the intersection
between brow line
112 and anterior line 114.
[0102] The location of pivot axis 138 is an important consideration. In some
embodiments
(including the illustrated embodiment, as shown best in Figure 7), pivot axis
138 passes
through mid-sagittal plane 120 in a zone 110 that is bounded by three lines:
(i) COG line
102, (ii) brow line 112, and (iii) anterior line 114. Zone 110 may also be
bounded in part by
the intersection of outer surface 106A of inner member 106 with mid-sagittal
plane 120. The
location of pivot axis 138 can impact the range of rotational motion of inner
member 106
relative to outer shell 104.
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[0103] In some embodiments, pivot axis 138 is located so that it intersects
mid-sagittal
plane 120 within a narrow area 122 near brow line 112. Without being bound by
theory,
locating pivot axis 138 in this narrow area 122 enables the creation of a
reasonably large
moment to offset the direction of head momentum. In some embodiments, it is
preferred to
locate pivot axis 138 so that it intersects mid-sagittal plane 120 as close to
brow line 112 as
possible, e.g. in some embodiments, within 6cm from brow line 112; in some
embodiments,
within 5cm from brow line 112; in some embodiments, within 4cm from brow line
112; in
some embodiments within 3cm from brow line 112; in some embodiments, within
2.5cm
from brow line 112; in some embodiments, within 2cm from brow line 112; in
some
embodiments, within 1.25cm from brow line 112; and in some embodiments, within
1cm
from brow line 112.
[0104] Helmet 100 comprises a pair of pivot joints 108 to enable the
rotational motion
between inner member 106 and outer shell 104 about pivot axis 138. To
determine a
location for pivot joints 108 and their corresponding pivot axes, one may
define an x-y
coincident with mid-sagittal plane 120 of helmet 100, such that when helmet
100 is worn on
head 10, the y-axis may be generally parallel with the superior/inferior
direction of head 10
and the x-axis may be generally parallel with the posterior/anterior direction
of head 10 (see
x-y plane in Figures 27A, 27B). A y-coordinate of pivot joints 108 may be
defined by the
midpoint 101 of a line connecting the arc center 157 of inner member 106 and
the arc
center 159 of outer shell 104, where the arc centers 157, 159 of inner member
106 and
outer shell 104 may be determined by curve-fitting circular curves to the
intersections of
either of the inner or outer surfaces of inner member 106 and outer shell 104
respectively
and the mid-sagittal plane 120 or to some other intersection of inner member
106 and outer
shell 104 to mid-sagittal plane 120. However, if the midpoint 101 is not
within an area where
inner member 106 intersects the mid-sagittal plane 120, the y-coordinate may
be moved
from the midpoint 101 to the nearest y-coordinate within an area that inner
member 106
intersects the mid-sagittal plane 120. Such a y-coordinate may be considered
to be a
geometric y ideal location. The geometric y ideal location may be adjusted
(e.g. in the y
dimension) to direct the expected contact location between inner member 106
and outer
.. shell 104 to a location with lower expected deformations and/or increased
shell-to-shell
space.
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[0105] Figure 27A depicts a schematic example of selecting a y-coordinate of
pivot joints
108 and their corresponding pivot axes. In the Figure 27A embodiment the y-
coordinate of
midpoint 101 between the arc-center 157 of inner member 106 and the arc-center
159 of
outer shell 104, illustrated by y-coordinate midpoint line 101A is within an
area where inner
.. member 106 intersects mid-sagittal plane 120. In such embodiments, the
ideal y-coordinate
of pivot joints 108 is located at the y-coordinate midpoint 101. Figure 27B
depicts a
schematic example of selecting a y-coordinate for pivot joints 108 where
midpoint 101 is
outside of an area where inner member 106 intersect mid-sagittal plane 120
such that the y-
coordinate of pivot joints 108 is moved to a nearest y-coordinate within an
area of inner
member 106 (as illustrated, in the Figure 27B embodiment, by exemplary
adjusted y-
coordinate line 103). It is noted that in general, the location of the
adjusted y-coordinate for
pivot joints 108 may depend on the location of the x-coordinate for pivot
joints 108.
[0106] An x-coordinate of pivot joints 108 may be selected to (without
limitation): (i)
maximize (or provide at or above an acceptable threshold level) the available
space for
relative pivotal movement between outer shell 104 and inner member 106; (ii)
increase the
applied torque on the head and neck; and/or (iii) decrease the mass moment of
inertia of
the head and neck that the applied torque needs to overcome. As the distance
between the
x-coordinate of pivot joints 108 and the midpoint 101 between the arc centers
157, 159 of
inner member 106 and outer shell 104 increases (e.g. the x-coordinate gets
further from the
.. midpoint) the range of pivotal movement between inner member 106 and outer
shell 104
may decrease. Increasing the distance between the x-coordinate of pivot joints
108 and
COG line 102 increases the torque applied to the head of the wearer when force
is applied,
facilitating flexion of the neck which may mitigate injury. Decreasing the
distance between
the x-coordinate and COG line 102 decreases the mass moment of inertia that
torque must
overcome.
[0107] In some embodiments, the x-coordinate of pivot joints 108 may be
positioned at a
location anterior to COG line 102 such that a maximal relative angular
rotation range
between inner member 106 and outer shell 104 (prior to contact therebetween)
is in a range
of 10 -30 . In some embodiments, the x-coordinate of pivot joints 108 is
located anterior to
.. COG line 102 and selected such that this maximal rotational range is 15 -25
. At pivot joint
x-coordinates in this range, rotation time, torque on the head of the wearer,
and/or angular
acceleration and velocity may be within suitable ranges. In some embodiments,
10 may be
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the minimum acceptable rotational range between inner member 106 and outer
shell 104
prior to contact therebetween. In some embodiments, this minimum acceptable
rotational
range is 15 . In some embodiments, this minimum acceptable rotational range is
20 . In
some embodiments, the x-coordinate of the pivot joints 108 may be located
between the
COG line 102 and the x-coordinate that is associated with minimum desired
relative angular
rotation range between inner member 106 and outer shell 104.
[0108] Pivot joints 108 may be made of:
= plastics (including reinforced plastics) (e.g. glass filled PEEK, UHMW-
PE, PPS, PC,
delrin/acetal, nylon, combinations thereof and/or the like);
= metal (e.g. stainless steel, aluminum, titanium, aluminum-bronze,
combinations
thereof and/or the like);
= combinations of metals and polymers;
= combinations thereof; and/or
= the like.
[0109] Figures 5 and 6 show a pin-style pivot joint 108. As shown in Figures 5
and 6,
helmet 100 comprises a pair of pivot joints 108 located symmetrically on
helmet 100 relative
to mid-sagittal plane 120. In one particular example embodiment shown in
Figure 6, pivot
joint 108 is provided by the engagement of a pin 144 within aligned apertures
146, 148
through inner member 106, a low-friction washer 150 and outer shell 104,
respectively. Pin
144 has a longitudinal axis that is aligned with pivot axis 138. Pivot joint
108 may allow only
one degree-of-freedom, i.e. outer shell 104 and inner member 106 may be
constrained (e.g.
by low-friction washer 15) against any sort of significant relative
translation motion, and may
be permitted only to rotate relative to one another about pivot axis 138.
Pivot axis 138 may
be common to pivot joints 108 on both sides of helmet 100. In other
embodiments, instead
of having pin 144 engage with inner member 106 and outer shell 104 through
aligned
apertures 146, 148, pin 144 may protrude directly from either one of inner
member 106 or
outer shell 104 and through a suitable aperture in the other one of inner
member 106 and
outer shell 104. The same pin-style pivot joints 108 may also be incorporated
in the
embodiments shown in Figures 19A, 19B, 20A, and 20B. Figures 19A, 19B, 20A and
20B
depict deployment devices within helmet 100 according to particular
embodiments. This pin-
style pivot joint is merely one possible embodiment of pivot joints 108.
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[0110] Some pivot joints 108 described herein (for example, the pin-style
pivot joints 108
described above in connection with Figures 5 and 6) permit relative rotation
of inner
member 106 and outer shell 104 about a pivot axis 138, but, in the absence of
deformation
of inner member 106, outer member 106 or one or both of pivot joints 108, do
not provide
any other degrees of freedom for relative movement of inner member 106 and
outer shell
104. As described herein, in some such embodiments, pivot joints 108 may be
located such
that pivot axis 138 is at least approximately the same (i.e. at least
approximately coincident
or co-linear) for pivot joints 108 on both sides of helmet 100. In some such
embodiments,
pivot joints 108 may be constructed to have a single (rotational) degree of
freedom (e.g.
about pivot axis 138), such that, in the absence of deformation of inner
member 106, outer
member 106 or one or both of pivot joints 108, there is only one corresponding
(rotational)
degree of freedom of relative movement between inner member 106 and outer
shell 104
(about pivot axis 138).
[0111] The inventors have discovered, however, that it may be desirable to
provide pivot
joints 108 with additional degrees of rotational freedom. Such additional
degrees of
rotational freedom can facilitate the operation of helmet 100 (e.g. the
relative movement
between inner member 106 and outer shell 104) to mitigate spinal cord injury
even where
inner member 104, outer shell 106 and/or pivot joints 108 are deformed (e.g.
due to impact).
In some such embodiments, each of pivot joints 108 may be operative to provide
three
degrees of rotational freedom, but, in the absence of deformation of inner
member 106,
outer member 106 or pivot joints 108, do not provide any translation degrees
of freedom. In
some such embodiments, pivot joints 108 on each side of helmet 100 may have
their own
corresponding pivot axes 138 and pivot joints may allow these pivot axes 138
to change
orientations. In some such embodiments, in the absence of deformation of inner
member
106, outer member 106 or pivot joints 108, the translational locations of the
respective pivot
axes 138 of pivot joints 108 may be fixed (e.g. at an origin which may in a
plane that
coincides with, or is located between, inner member 106 and outer shell 104),
while the
orientations of the respect pivot axes 138 may be permitted to change provided
that the
translational locations of their respective origins are fixed (i.e. provided
that pivot axes 138
still extend through their respective origins). Such functionality (multiple
rotational degrees
of freedom and/or rotational about an axis where the orientation of the axis
is permitted to
change) may be provided by surface-bearing pivot joints, for example. Such
surface-bearing
pivot joints may comprise a first component (e.g. a male component) comprising
a first
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surface and a second component (e.g. a female component) comprising a second
surface
that is complementary to the first surface to permit slidable engagement
between the first
and second complementary surfaces. The first and second complementary surfaces
may be
curved.
[0112] One type of surface-bearing pivot joint that permits multiple
rotational degrees of
freedom and/or rotational about an axis where the orientation of the axis is
permitted to
change is known as a full-socket type pivot joint. One or both of pivot joints
108 may
comprise a full-socket type pivot joint. Figures 28A, 28B and 28C
(collectively, Figure 28)
depict perspective views of an example full-socket type pivot joint 400. Full-
socket type
pivot joint 400 comprises female component 402 and male component 404 that
correspondingly fit together (see e.g. Figure 28A which depicts a perspective
of an example
assembled full-socket type pivot joint 400). One of female component 402 and
male
component 404 may be mounted to inner member 106 and the other one of female
component 402 and male component 404 may be mounted to outer shell 104. Figure
28B
depicts a perspective view of female component 402. Female component 402
comprises
cavity 403 defined by one or more curved surfaces 405, which may be
cylindrically shaped,
semi-spherically shaped or have some other suitable curved profile. Figure 28C
depicts a
perspective view of male component 404. Male component 404 comprises
protrusion 406.
Protrusion 406 comprises one or more curved surfaces 407. Curved surface(s)
407 of male
component 404 are shaped to be complementary to curved surface(s) 405 of
female
component 402 such that male component 404 and female component 402 engage
with
one another (e.g. by slidable engagement of curved surfaces 405, 407) to
facilitate
movement of male component 404 in relation to female component 402 in three
degrees of
rotational freedom or about a pivot axis where an orientation of the pivot
axis is permitted to
change. The shapes of curved surface 407 and curved surface 405 may vary
between
embodiments. For example, as depicted in Figures 28C, the shape of curved
surface 407 is
such that curved surface ends in generally planar face 408. In other
embodiments, the
extent of curved surface 407 may be lesser or greater. Variations in the size
and/or shape
of curved surface 407 may directly correspond to varying sizes of generally
planar face 408.
For example, in some embodiments, the size and curvature of curved surface 407
may be
selected such that protrusion 406 is half-spherical or half-ellipsoidal in
shape. Curved
surface 405 may be complementary to curved surface 407.
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[0113] Another type of surface-bearing pivot joint that permits multiple
rotational degrees of
freedom and/or rotational about an axis where the orientation of the axis is
permitted to
change is known as a half-socket type ball joint. One or both of pivot joints
108 may
comprise a half-socket type ball joint. Figures 29A, 29B and 29C
(collectively, Figure 29)
depict perspective views of example half-socket type ball joint 410. Half-
socket type ball
joint 410 comprises female component 412 and male component 414 that
correspondingly
fit together (see e.g. Figure 29A which depicts a perspective example of a
half-socket type
ball joint 410). One of female component 412 and male component 414 may be
mounted to
inner member 106 and the other one of female component 412 and male component
414
may be mounted to outer shell 104. Figure 29B depicts a perspective of male
component
414. Male component 414 comprises protrusion 416. Protrusion 416 may have one
or more
curved surfaces 417. In varying embodiments curved surface 417 may vary in
size and or
shape. For example, as depicted in Figure 29B, in some embodiments, curved
surface 417
may be substantially half-spherical in shape. In other embodiments, the extent
of curved
.. surface 417 may be different, resulting in a shape that is semi-spherical
or partially
spherical, for example. In other embodiments, curved surface 417 may have
other curved
shapes. Curved surface 417 is complementary to, and engages with, one or more
curved
surfaces 415 provided by one or more arms 419 of female component 412 (shown
in Figure
29C). Female component 412 comprises cavity 413 that is defined by one or more
curved
.. surfaces 415 which may be curved in a manner that is complementary to
curved surface
417. The embodiment depicted in Figure 29C depicts one arm 419 that comprises
a
generally semi-spherical surface 415. However, in other embodiments, cavity
413 may be
defined by curved surfaces 415 provided by a plurality of arms 419.
[0114] Pivot joints 108 may additionally or alternatively comprise one or more
of disk locks,
snap locks, t-joints (e.g. Figure 31), nuts, bolts and ridges and grooves
(e.g. Figure 30
shows one or more grooves which correspond to one or more ridges which when
put
together pivot). Other ball-socket type joints may include a snap fit ball
socket joint and/or a
2-part socket.
[0115] Pivot joints 108 may be custom made or made using off the shelf parts.
Multiple off
the shelf parts may be combined to create a custom pivot joint 108. Off the
shelf parts may
include one or more of, bolts, washers, nuts, clip bearings, etc. Off the
shelf parts may be
made of plastics, reinforced plastics, metals, fiberglass, carbon fiber,
combinations thereof
and/or the like.
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[0116] Pivot joints 108 facilitate the pivotal coupling of outer shell 104 and
inner member
106 to facilitate rotational movement of outer shell 104 relative to inner
member 106 about
pivot axis 138. In some embodiments, such as full-socket type pivot joints
(Figure 28), half-
socket type ball joints (Figure 29) or other surface bearing pivot joints, one
of the male
component and the female component may be rigidly mounted or connected to
inner
member 106 (or rigidly mounted to inner member 106 but for one degree of
rotational
freedom) and the other one of the male component and the female component may
be
rigidly mounted or connected to the outer shell 104 (or rigidly mounted to
outer shell 104 but
for one degree of rotational freedom).
[0117] Components of pivot joint 108 (e.g. male components or female
components) may
be coupled to inner member 106 by means of one or more of:
= integration with inner member 106 by inlaying the component of pivot
joint 108 in
inner member 106;
= mechanically coupling the component of pivot joint 108 to inner member
106 (e.g.
using one or more of drilled holes, bolts, plastic melting bolts, etc.); and
= adhering the component of pivot joint 108 to inner member 106 using an
adhesive
(e.g. 3M glue, epoxy, etc.).
[0118] Components of pivot joints 108 may each be coupled to outer shell 104
by means of
a recess in outer shell 104 and adhesive. Alternatively or additionally
components of pivot
joints 108 may each be coupled to outer shell 104 through mechanical means
(e.g. drilled
holes, bolts, plastic melting bolts, etc.) and/or adhesive (e.g. 3M glue,
epoxy, etc.).
[0119] To reduce the likelihood that components of pivot joints 108 will peel
or separate
from outer shell 104 (or inner member 106) with the application of force, the
coupling of
components of pivot joint 108 to outer shell 104 (or inner member 104) may
include one or
more of:
= The component(s) 108A of pivot joints 108 may be tapered in one or more
dimensions. It may be desirable to taper pivot joint components 108A so as to
provide thinner in regions where a peeling stress is considered to be more
likely. The
thickness of pivot joint component 108A may be tapered as shown in Figures 32,
33A and 33B. Tapers may or may not be linear. Additionally or alternatively,
pivot
joint component 108A may be aperture or provided with other surface profiles
(as
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shown in the embodiment of Figures 33A and 33B) to provide for improved
adhesive
bonding (relative to flat or planar surfaces).
= Pivot joint components 108A may be coupled to outer shell 104 such that
outer shell
104 generally contacts two perpendicular ends of pivot joint component 108A
and
partially contacts a third end of pivot joint component 108A as shown in
Figure 34 in
a "hook" like attachment.
= Pivot joint components 108A may be coupled to outer shell 104 using one
or more
bolts (see e.g. Figure 35), rivets and/or similar fasteners.
= Pivot joint components 108A may be shaped to have an increased area in
regions of
higher stress which in turn may produce a larger bond area between pivot joint
component 108A and outer shell 104 in high stress regions (see e.g. Figure 36
in
which the larger areas of pivot joint component 108A have higher stress).
[0120] Helmet 100 also comprises deployment device 124 (one embodiment of
which is
shown in Figures 19A and 19B) to maintain an initial angular relationship
(about pivot axis
138) between inner member 106 and outer shell 104. In the absence of
sufficient external
force, deployment device 124 constrains rotational motion between inner member
106 and
outer shell 104 about pivot axis 138 (e.g. to within a minimum rotational
amount). That is, in
the absence of sufficient external force, deployment device 124 constrains the
initial relative
angular orientations of inner member 106 and outer shell 104 about pivot axis
138 (e.g. to
within minimum relative angular orientations). Deployment device 124 may
constrain the
relative motion between inner member 106 and outer shell 104 by applying force
between
inner member 106 and outer shell 104 (or between any components of the pivotal
coupling
between inner member 106 and outer shell 104) that tends to prevent relative
rotation.
When the helmet 100 receives an impact having sufficient force (e.g. an
external force
greater than a configurable threshold), deployment device 124 deploys to
permit relative
angular rotation between outer shell 104 and inner member 106 about pivot axis
138. In
some embodiments, the threshold for deployment of deployment device 124 is
somewhere
between and including 400N to 1750N, as measured at the top of helmet 100. In
some
embodiments, the threshold for deployment of deployment device 124 is in a
range of
1200N-1500N as measured at the top of helmet 100. In some embodiments, this
threshold
is in a range of 1000N-1200N as measured at the top of helmet 100. In some
embodiments, this threshold is in a range of 750-1000N as measured at the top
of helmet
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100. Deployment device 124 may be in an initial configuration in the absence
of sufficient
external force and a deployment configuration (different from the initial
configuration) when
helmet 100 receives an impact having sufficient force.
[0121] One function of deployment device 124 is to maintain an initial angular
relationship
between inner member 106 and outer shell 104 about pivot axis 138 until helmet
100
receives an external (e.g. impact) force greater than a configurable
threshold. Deployment
device 124 may be characterized as being in an initial configuration prior to
receiving such
an impact force. The maintaining of the initial angular relationship minimizes
mechanical
rattling and/or unwanted motions during activity (e.g. sporting activity).
Another function of
deployment device 124 may be to mitigate head 10 decoupling from inner member
106. The
inventors have determined that if inner member 106 begins to rotate before the
impact force
on outer shell 104 builds to at least 300-500N, then head 10 does not 'stick'
with inner
member 106 and will likely slip and move independently of inner member 106.
[0122] Deployment device 124 may also enable sufficient frictional force to
build up when
helmet 100 receives an impact. When helmet 100 receives an impact having a
force above
the threshold of deployment device 124, the friction between outer shell 104
and ground
may be large enough to change the momentum of head 10. In other words, outer
shell 104
may be able to roll/rotate without slipping if the frictional force between
outer shell 104 and
the impact surface is sufficiently high to prevent slipping. In contrast, if
the motion of outer
shell 104 at the impact surface is slipping, then outer shell 104 could rotate
but the head
and neck could continue with the incoming momentum.
[0123] Deployment device 124 may be positioned at any suitable location within
and/or on
helmet 100. Deployment device 124 may be positioned within one or more pivot
joints 108,
1cm to 3cm from one or more pivot joints 108 and/or at the back of helmet 100.
The back of
helmet 100 may be defined by the region of helmet 100 posterior to the corona!
plane 12
(see Figure 3) or posterior to a plane containing COG line 102 and orthogonal
to mid-
sagittal plane 120. Alternatively or additionally the back of helmet 100 may
be defined as
the posterior medial region of helmet 100.
[0124] In some embodiments (in particular in the embodiment of Figures 19A and
19B)
deployment device 124 comprises a shear pin 128. Shear pin 128 may be
considered to be
a frangible deployment device 124. Shear pin 128 may be configured to break
when helmet
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100 is struck by a force greater than a configurable threshold (e.g. greater
than 1000N or
any of the other thresholds or threshold ranges described herein). Shear pin
128 can be
placed in any suitable location between outer shell 104 and inner member 106.
One or
more shear pins 128 may be placed to connect outer shell 104 to inner member
106. In
some embodiments, shear pin 128 is placed near a posterior-lateral portion of
helmet 100.
As shown in Figure 19B, helmet 100 of the illustrated embodiment comprises a
pair of shear
pins 128 located symmetrically on helmet 100 relative to mid-sagittal plane
120. Shear pins
128 are located near a posterior-lateral portion of helmet 100. A lateral
portion of helmet
100 may be relatively flat (minimal curvature) and therefore it would be
relatively easy to
mount shear pin 128. A posterior portion of helmet 100 provides a relatively
large moment
arm with respect to pivot axis 138 so that a shear pin 128 located in this
area would
experience less shear force and a relatively low rigidity pin 128 may still be
used in
deployment device 124 to avoid accidental deployment/breakage.
[0125] When shear pin 128 breaks, it frees inner member 106 and outer shell
104 from their
initial relative angular relationship and outer shell 104 is able to rotate
relative to inner
member 106 about pivot axis 138 (by the action of pivot joints 108).
[0126] In some embodiments, deployment device 124 comprises a pair of
polylactic acid
(PLA) plastic shear pins installed on the left and right sides of helmet 100.
Such pins having
diameters of 2.85mm can each resist up to 477N.
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For example, if a shear pin with 2.85 mm diameter
made from PLA (shear strength, r = 33 MPa) is used:
Cross-sectional area of shear pin = ii (0.00285)2/ 4
Ashear
= 6.38 x 10 -6 [m2]
(6.38 x 10 [m2])(33 x 10 [Pa])
Fshear max = Ashear =
= 210.54 [N]
For two pins (one per side), F = 210.54 [N] * 2
shear max double
= 421.80 [N]
F =F d
w, max shear max double s id P
= (421.80 [N]) (0.04 [m]/0.17 [m])
= 99.25 [N]
This means that the shear pin will break when Faxial reaches:
=F w max / sin(a)
Faxial max
= 99.25 [N] sin(12 )
= 477.35 [N]
[0127] In other embodiments, deployment device 124 may comprise other
frangible or
breakable devices. For example, deployment device 124 may comprise one or more
breakable seals. Frangible deployment devices 124 may behave in a manner
generally
similar to shear pin 128. For example, frangible deployment devices 124 may
maintain an
initial configuration between inner member 106 and outer shell 104, frangible
deployment
devices 124 may break when sufficient force is applied to them, where such a
break allows
inner member 106 to pivot in relation to outer shell 104 (by the action of
pivot joints 108).
[0128] In another example embodiment, deployment device 124 comprises an
elastic
attachment member 128, 164 (e.g. an elastomeric tether, instead of a shear
pin) to hold
inner member 106 and outer shell 104 in their initial relative angular
positions. A graphic
representation of the elastic attachment member 128, 164 may be similar to
that of a shear
pin 128 as shown in Figures 19A and 19B. Prior to deployment (i.e. prior to
experiencing
forces in a range associated with an impact), elastic attachment member 128,
164 may
permit some relative rotational movement between inner member 106 and outer
shell 104.
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In some embodiments, this pre-deployment relative rotation is less than 5 . In
some
embodiments, this pre-deployment relative rotation is less than 2.5 . In some
embodiments,
this pre-deployment relative rotation is less than 1.25 . Upon deployment, the
elastic
attachment member 128, 164 stretches or otherwise deforms and allows rotation
(or a
larger range of relative rotation) of inner member 106 with respect to outer
shell 104 about
pivot axis 138. In some embodiments, this larger range of permissible relative
rotation is
greater than 5 . In some embodiments, this larger range of permissible
relative rotation is
greater than 10 . In some embodiments, this larger range of permissible
relative rotation is
greater than 15 . In some embodiments, elastic attachment member 128, 164 may
be
configured to break if the force applied to helmet 100 is greater than a
configurable
threshold.
[0129] Deployment device 124 may comprise a snap-fit connector 154 as shown in
Figures
20A and 20B. Snap-fit connector 154 comprises a female component 156 and a
male
component 158 that form a restorative deformation fit with one another. That
is, when male
component 158 is inserted into female component 156, one or both of components
156, 158
is initially elastically deformed and then, when the connection is made, there
is restorative
force that tends to restore this elastic deformation causing the components
156, 158 to
"snap-fit" together. When female component 156 engages male component 158,
snap-fit
connector 154 connects outer shell 104 with inner member 106. Female component
156
separates from male component 158 when a sufficient force deforms one or both
of
components 156, 158 allowing them to separate again ¨ e.g. when helmet 100 is
struck by
a force greater than a threshold. In some embodiments, this threshold is
1000N. In some
embodiments, this threshold is 750N. In some embodiments, this threshold is
1500N.
[0130] Deployment device 124 may comprise a mechanistic deployment device. For
example, deployment device 124 may comprise one or more torsion springs. Upon
deployment, the one or more torsion springs stretch or otherwise deform and
allow rotation
(or a larger range of relative rotation) of inner member 106 with respect to
outer shell 104
about pivot axis 138. In some embodiments, this larger range of permissible
relative rotation
is greater than 5 . In some embodiments, this larger range of permissible
relative rotation is
greater than 10 . In some embodiments, this larger range of permissible
relative rotation is
greater than 15 . In some embodiments, the one or more torsion springs may be
configured
to break if the force applied to helmet 100 is greater than a configurable
threshold.
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[0131] In some other embodiments, pivot joints 108 and deployment devices 124
are
incorporated together as one mechanism. For example, Figures 21A-B, 22A-B, 23A-
C, and
24A-C show pivot joints with built-in deployment devices. Figures 21A-B show a
pivot joint
160 having a pin 162 and elastic attachment members 164 that are coupled to
pin 162. Pin
162 allows one degree-of-freedom rotation of inner member 106 relative to
outer shell 104.
Pin 162 is positioned so that a longitudinal axis of pin 162 is aligned with
pivot axis 138.
Elastic attachment members 164 connect pin 162 with inner member 106. Pivot
joint 160
may be provided by the engagement of pin 162 within aligned apertures through
inner
member 106 and outer shell 104. In some other embodiments, pin 162 is
integrally formed
with either one of inner member 106 or outer shell 104, so that the other
shell is rotatable
relative to the integrally formed pin-shell assembly about pivot axis 138.
Elastic attachment
members 164 are coupled to pin 162 and function to maintain an initial
relative angular
relationship between inner member 106 and outer shell 104 (e.g. to within
minimum relative
angular orientations) until helmet 100 receives sufficient impact force. In
some
embodiments, this minimum relative rotation is less than 50. In some
embodiments, this
minimum relative rotation is less than 2.5 . In some embodiments, this minimum
relative
rotation is less than 1.25 . When sufficient external force is applied to
helmet 100 (e.g. on
impact), elastic attachment members 164 stretch or otherwise deform to thereby
allow a
larger range of rotation of inner member 106 with respect to outer shell 104
about pivot axis
138. In some embodiments, this larger range of permissible relative rotation
is greater than
5 . In some embodiments, this larger range of permissible relative rotation is
greater than
10 . This larger range of permissible relative rotation is greater than 15 .
In some
embodiments, elastic members 164 may be configured to break if the force
applied to
helmet 100 is greater than a configurable threshold.
[0132] Figures 22A-B show a pivot joint 170 having a female component 172 and
a male
component 174. In the illustrated embodiment, female component 172 is coupled
to outer
shell 104 and male component 174 is coupled to inner member 106, although this
configuration could be reversed. Female component 172 has features that are
complimentary to male component 174. First, female component 172 is shaped to
define a
generally cylindrical bore and male component 174 is shaped to have a
cylindrical surface
complementary to the bore of female component 172 so that male component 174
fits at
least partially in the bore of female component 172. Female component 172
defines a
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radially extending groove 176 with an inner surface 175. Male component 174
has a
deformable or break-away key 178 extending from a side wall 179 and
complementary in
shape to groove 176, so that key 178 fits in groove 176. When helmet 100
receives an
impact force greater than a configurable threshold, key 178 is sheared off
from male
component 174 (and/or one or both of key 178 and groove 176 deform), so that
the
interaction of key 178 and groove 176 no longer stops male component 174 from
rotating
relative to female component 172. Relative rotation between male and female
components
174, 172 in turn allows inner member 106 to rotate relative to outer shell 104
about pivot
axis 138.
[0133] Figures 23A-C show a pivot joint 180 having a built-in snap-fit
mechanism. Pivot joint
180 has a female component 182 and a male component 184 that is complimentary
to male
component 182. In the illustrated embodiment, female component 182 has a base
186 that
is secured to an inner surface of outer shell 104 and male component 184 has a
base 181
that is secured to an outer surface of inner member 106, although this
configuration could
be reversed. Male component 184 has a shaft 183 extending from base 181.
Female
component 182 and male component 184 have structural features (i) to enable
female
component 182 to be rotatable relative to male component 184 and (ii) to
retain female
component 182 and male component 184 in an initial angular arrangement. First,
to enable
relative rotation of female component 182 and male component 184, shaft 183 of
male
component 184 functions as a pivot pin. Shaft 183 allows only one degree-of-
freedom
rotation of female component 182 relative to male component 184, which in turn
enables
inner member 106 to be rotatable relative to outer shell 104 about pivot axis
138. Shaft 183
engages with female component 182 in any suitable manner to allow the one
degree-of-
freedom rotation of female component 182 relative to male component 184. For
example,
base 186 of female component 182 may define a concave portion 189 that is
shaped to
restrict translational movement of male component 184 relative to female
component 182.
Shaft 183 may be shaped to define a generally cylindrical bore 185 and female
component
182 may provide a pin 188 that is shaped to fit at least partially in
generally cylindrical bore
185. Generally cylindrical bore 185 has a longitudinal axis that is aligned
with pivot axis 138.
Pin 188 extends from a base 186 of female component 182 and when pin 188 fits
in
generally cylindrical bore 185, pin 188 is positioned in a direction along
pivot axis 138. Pin
188 and generally cylindrical bore 185 are optional and their engagement
enables only one-
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degree of freedom between female component 182 and male component 184. Second,
to
retain female component 182 and male component 184 in an initial angular
arrangement, a
snap-fit mechanism may be used. For example, shaft 183 may comprise one or
more radial
protrusions 187A shaped to fit into one or more corresponding indents 189A on
female
component 182. When the radial protrusion 187A is located within the indent
189A, their
engagement stops the relative rotation between female component 182 and male
component 184, which in turn stops the relative rotation between inner member
106 and
outer shell 104. When the radial protrusion 187A exits from the indent 189A,
their
disengagement allows the relative rotation between female component 182 and
male
component 184, which in turn allows the relative rotation between inner member
106 and
outer shell 104.
[0134] With reference to Figures 23A-C, shaft 183 comprises two cantilever
arms 187 that
engage concaved portion 189. Cantilever arms 187 each have a radial protrusion
187A and
concaved portion 189 provides two corresponding radially extending concavities
189A.
Radial protrusion 187A may be made of a deformable material. When helmet 100
receives
an impact of greater than a configurable threshold, radial protrusion 187A
deforms and exits
from radially extending concavities 189A so that male component 184 can rotate
relative to
female component 182. More than two cantilever arms 187 may be present, so
that discrete
levels of angular rotation are permitted. For example, four cantilever arms
187 may be
present and may be symmetrically positioned at uniform angular intervals about
shaft 183.
In such an embodiment, a discrete level of angular rotation of 90 is
permitted.
[0135] Figures 24A-C show a pivot joint 190 with a gear-like profile. Pivot
joint 190 has a
female component 192 and a male component 194. Female component 192 is coupled
to
outer shell 104 and male component 194 is coupled to inner member 106. Female
.. component 192 has features that are complimentary to male component 194.
First, female
component 192 is shaped to define a bore and male component 194 is shaped to
define a
surface complementary to the bore of female component 192 so that male
component 194
fits at least partially within female component 192. The surface of male
component 194 has
a gear-like profile/ratchet interface. Correspondingly, the bore of female
component 192 has
.. a complimentary gear-like profile/ratchet interface. The gear-like
engagement between
female component 192 and male component 194 (i) enables discrete levels of
angular
rotation and (ii) retains female component 192 and male component 194 in an
initial angular
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arrangement. Female component 192 only rotates relative to male component 194
when
helmet 100 receives an impact force greater than a configurable threshold.
Such a force or
torque causes deformation in either female component 192 or male component 194
which
in turn permits discrete amounts of angular rotation of female component 192
relative to
male component 194. Once the force falls below the configurable threshold,
rotation of
female component 192 relative to male component 194 is stopped. Overall, every
incremental turn of male component 194 relative to female component 192 will
provide a
certain level of torsional resistance.
[0136] These example embodiments show that pivot joints 108 and deployment
device 124
may be separate structural components or may be combined into a single
mechanism.
[0137] Helmet 100 may comprise a protective liner (not shown) located on an
interior
surface of inner member 106. Protective liner may be similar to the protective
liner provided
on prior art helmets and may comprise foam materials of any variable density.
[0138] Helmet 100 may also comprise a retention strap (not shown), chin strap
or other
suitable means for securing helmet 100 to head 10.
[0139] Helmet 100 can be used for mitigating cervical spine injuries and/or
fractures.
Responsive to an impact force greater than a configurable threshold,
deployment device
124 is deployed to free inner member 106 and outer shell 104 from their
initial relative
angular relationship and outer shell 104 is able to rotate relative to inner
member 106 about
pivot axis 138. In the event of a head-first impact, helmet 100 induces
flexion of the neck
and thereby mitigates cervical spine fractures.
Second Helmet Embodiment
[0140] Figure 12 shows a helmet 200 according to another example embodiment.
Helmet
200 is substantially similar to helmet 100 except that helmet 200 comprises
one or more
beveled regions 249A defined between a corresponding pair of
extremities/apexes 251A,
251B on the outer surface 204B of outer shell 204 or at least at the
intersection 204C of the
outer surface 204B of outer shell 204 with mid-sagittal plane 220. These
apexes 251A,
251B (collectively, apexes 251) may function to induce additional torque
between outer
shell 204 and inner shell 206 because of the interaction between outer shell
204 and the
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ground (or other impact surface). Components of helmet 200 that correspond to
the
components of helmet 100 are shown with reference numerals incremented by 100.
[0141] Without limitation, helmet 200 may be useful for sports that involve
low-friction
impact surfaces such as ice and/or snow. Upon impact, low-friction impact
surfaces may
permit a helmet to slide on such surfaces and, because of such sliding, may
not (via friction
alone) produce the desired torque between the inner member and outer shell to
facilitate
the relative pivotal motion. In these scenarios, the underlying mechanics
desired to elicit
relative pivotal motion between the inner member and the outer shell and the
corresponding
neck flexion may be different than those involving relatively higher friction
impact surfaces.
A back-up feature to combat slippery surfaces is to shape the sagittal-plane
profile 204C of
the outer surface 204B of the outer shell 204 such that there are one or more
beveled
regions 249 between corresponding pairs of apexes 251A, 251B.
[0142] For example, the sagittal-plane profile 204C of the outer surface 204B
of outer shell
204 in the Figure 12 helmet 200 comprises one or more bevelled regions 249A
which are
.. located between apexes 251A, 251B respectively. In the illustrated Figure
12 embodiment,
bevelled regions 249 of sagittal-plane profile 204C are straight lines. This
is not absolutely
necessary. In some embodiments, the radii of curvature of bevelled regions 249
of sagittal-
plane profile 204C may be relatively large in comparison to the corresponding
radii of
curvature of apexes 251 at the edges of the bevelled regions 249. In the
illustrated Figure
12 embodiment, apex 251B is coincident with COG line 202, although this is not
necessary.
If apex 251B is coincident with COG line 202, apex 251B may be referred to as
COG apex
251B. Helmet 200 may comprise one or more anterior bevelled surfaces 249A
located
anterior to COG apex 251B. For example, helmet 200 comprises anterior bevelled
surface
249A located anterior to COG apex 251B and between COG apex 251B and apex
251A. In
some embodiments, helmet 200 may comprise one or more posterior bevelled
surfaces
located posterior to COG apex 251B.
[0143] The outer surface 204B of outer shell 204 (with its bevelled surfaces
249A and
apexes 251A, 251B) help to create additional force between helmet 200 and an
impact
surface where such force is oriented to cause torque between outer shell 204
and inner
member 206 that tends to cause relative pivotal movement therebetween and to
induce
neck flexion both in the case of a high-friction impact surface and a low-
friction impact
surface. This effect can be seen in Figure 13 for a relatively high-friction
impact surface. In
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the Figure 13 illustration, the interaction between outer shell 204
(specifically, COG apex
251B and bevelled surface 249A) and the impact surface generates frictional
torque which
tends to pivot outer shell 204 in a clockwise direction and/or inner shell in
a counter-
clockwise direction (in the illustrated view) about pivot axis 238.
[0144] Figures 14A-C illustrate the interaction of helmet 200 with a low-
friction impact
surface. Upon axially striking a slippery surface, a downward force is
transferred onto outer
shell 204 via pivot joint 208, creating a clockwise (in the illustrated view)
torque on outer
shell 204 about pivot axis 238 which tends to move top edge of visor cavity
216 of outer
shell 204 upwardly to be further above eyebrows. This clockwise rotation is
shown as the
helmet transitions from the initial impact (Figure 14A) to a slightly rotated
position (Figure
14B). Due to a lack of friction between the impact surface and outer shell
204, outer shell
204 may not be able to continue to rotate past the configuration shown in
Figure 214B and,
instead, outer shell 204 may slide against the impact surface until apex 251A
stops the
relative clockwise rotation of outer shell 204. Contact point between helmet
200 and the
impact surface is now shifted to thereby impose a counter clockwise torque on
the helmet-
head-neck assembly.
[0145] The location of contact force imparted on outer shell 204 is initially
at the location of
apex 251B. This force manifests itself as clockwise torque (on outer shell 204
about pivot
axis 238) which tends to cause the outer shell to pivot relative to the inner
member in a
clockwise direction. This clockwise rotation is shown as the helmet
transitions from the
initial impact (Figure 14A) to a slightly rotated position (Figure 14B). The
rotation of the
outer shell 204 is halted when the bevel 251A contacts the ground thus
imparting a counter
clockwise moment on the outer shell. At this point the momentum of the head
obtains an
anterior component and the head and neck move into flexion.
[0146] In other respects, helmet 200 may be similar to helmet 100 described
and illustrated
herein.
Use of Multi-Shell Helmet to Prevent Spinal Injury
[0147] For brevity and without loss of generality, the description of this
section focusses on
helmet 100, but is also applicable to helmet 200 and other helmets described
herein. As
shown in Figure 15, outer shell 104 rotates relative to inner member 106 about
pivot axis
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138. The location of pivot axis 138 is purposefully placed anterior to COG
line 102. As
shown in the middle pane of Figure 15, this location of pivot axis 138 enables
head 10 and
inner member 106 to exert a torque on pivot joint 208 (about pivot axis 138)
which tends to
cause neck flexion and head 10 to move toward the front of the torso of the
wearer (i.e. the
head and neck are subjected to a counter-clockwise torque in the illustrated
view).
Simultaneously, this location of pivot axis 138 enables outer shell 104 to
experience a
torque on pivot joint 208 (about pivot axis 138) in the opposing angular
direction.
[0148] Table 1 shows changes to experimentally measured loads and
accelerations as a result of
the pivot motion between inner member 106 and outer shell 104 conducted on a
commercial helmet
(Figures 17 and 18). All drops were tested at impact speeds within 3.0 to 3.2
m/s.
Table 1
Peak Forces Peak
Impact Surface
Lower Neck Upper Neck Linear
Flat (head-first 40% 47% 42% reduction
+ 15 deg (posterior 42% 31% 62% reduction
- 15 deg (anterior 40% 46% 38% reduction
Retrofitting a Single-Shell Helmet to Provide Dual Shell Functionality
[0149] Helmet 100 can be made by retrofitting a single-shell helmet. The
single-shell helmet
comprises a first shell and an inner protective liner. The inner protective
liner may be a
single-impact protective liner (e.g. EPS) or a multiple-impact protective
liner (e.g. EVA). The
single-shell helmet with a single-impact protective liner may be referred
herein to as single-
impact, single-shell helmet. The single-shell helmet with a multiple-impact
protective liner
may be referred herein to as multiple-impact, single shell helmet.
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[0150] Figure 16 shows a method 300 for retrofitting a single-shell helmet to
provide a dual-
shell helmet 100.
[0151] At step 302, the location of coupling zone 110 is determined. Coupling
zone 110 is
bounded by three lines embedded in mid-sagittal plane 120 of helmet 100: (i)
COG line 102,
(ii) brow line 112, and (iii) anterior line 114. As discussed above, the
location of COG line
102 may be specified by a helmet manufacturer, especially if the manufacturer
uses the
standardized Anthropomorphic Test Devices ("ATDs"), commonly referred to as
dummies,
to design the dimensions and shapes of the helmets.
[0152] At step 304, a second shell is pivotably coupled to the first shell of
the single-shell
helmet to create a multi-shell structure. The first shell is movable relative
to the second shell
by rotation about a laterally oriented pivot axis 138. Pivot axis 138 is
parallel to a lateral
plane and orthogonal to a mid-sagittal plane of the multi-shell structure. The
pivot axis also
passes the coupling zone 110 (see above description of pivot axis 138 and
coupling zone
110). The second shell may go within the single-shell helmet or outside of the
single-shell
helmet. The second shell may span the entirety or a portion of the single-
shell helmet.
[0153] The second shell may be coupled to the first shell via a pivot
mechanism. The
second shell can be coupled to the first shell by pivot joint 108.
[0154] At step 306, deployment device 124 is added to detachably couple outer
shell 104
and inner member 106 together. As discussed above, in the absence of
sufficient external
force, deployment device 124 constrains rotational motion between inner member
106 and
outer shell 104 about pivot axis 138 (e.g. to within a minimum rotational
amount). That is, in
the absence of sufficient external force, deployment device 126 constrains the
initial relative
angular orientations of inner member 106 and outer shell 104 about pivot axis
138 (e.g. to
within minimum relative angular orientations). Deployment device 124 may
constrain the
relative motion between inner member 106 and outer shell 104 by applying force
between
inner member 106 and outer shell 104 (or between any components of the pivotal
coupling
between inner member 106 and outer shell 104) that tends to prevent relative
rotation.
When the helmet receives an impact having sufficient force (e.g. an external
force greater
than a threshold), deployment device 124 deploys to permit relative angular
rotation
between outer shell 104 and inner member 106 about pivot axis 138. In some
embodiments, deployment device 124 may be in an initial configuration in the
absence of
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sufficient external force and a deployment configuration (different from the
initial
configuration) when the helmet receives an impact having sufficient force.
Deployment
device 124 may also permit sufficient frictional force to build up when the
helmet 100
receives an impact. This frictional force may then change the direction of the
head's
momentum.
[0155] Figure 17A shows an example single use single shell helmet retrofitted
to add an
inner member 106 to provide the dual shell helmet functionality described
herein. Figure
17B shows an example multi-use single shell helmet retrofitted to add an inner
member 106
to provide the dual shell helmet functionality described herein.
[0156] Figure 18 shows an example single shell helmet retrofitted to add an
outer shell 104
to provide the dual shell helmet functionality described herein.
[0157] While a number of exemplary aspects and embodiments have been discussed
above, those of skill in the art will recognize certain modifications,
permutations, additions
and sub-combinations thereof. It is therefore intended that the following
appended claims
and claims hereafter introduced are interpreted to include all such
modifications,
permutations, additions and sub-combinations as are consistent with the
broadest
interpretation of the specification as a whole.
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