Note: Descriptions are shown in the official language in which they were submitted.
TITLE
[0001] Helmet Liner
FIELD
[0002] There is described a helmet liner, used to line a helmet which
serves as protective
head gear.
BACKGROUND
[0003] United States Patent 10,143,255 (Golnaraghi et al) describes a
danger of injuries
occurring to a head of a person wearing protective head gear as a result of
rotational
acceleration. The reason for this is that, upon impact, an outer interior
surface of the protective
head gear stops instantly, while the head keeps moving. The solution proposed
by Golnaraghi
et al is to provide an impact diverting mechanism which includes a top layer
which attaches to
the interior surface of the helmet and a bottom layer that attaches to the
liner of the helmet.
The top layer is disposed adjacent to and mechanically connected to the bottom
layer. Upon
impact, the top layer shifts relative to the bottom layer. This relative
movement dissipates
kinetic energy. A preferred embodiment is described by Golnaraghi et al that
has an
intermediate layer positioned between the top layer and the bottom layer. The
intermediate
layer may include a liquid-gel lubricant to facilitate slipping movement of
the top layer relative
to the bottom layer.
[0004] This document is the culmination of several years of research into
lubricants and
other materials to facilitate slipping movement of the top layer relative to
the bottom layer.
SUMMARY
[0005] There is provided a helmet liner which includes a liner body
having an impact
absorbing bottom layer, a slippery intermediate layer and a top fabric layer.
The intermediate
layer overlies and is secured to the bottom layer. The top fabric layer
overlies the intermediate
layer. The top fabric layer has a perimeter and a central portion. The top
fabric layer is secured
on the perimeter leaving the central portion of the top fabric layer free to
accommodate relative
sliding movement of the intermediate layer.
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Date Recue/Date Received 2021-05-28
[0006] The
innovative aspect of the helmet liner described above is the use of a top
fabric
layer. At the start of the research, fabric would not have been considered
suitable for the top
layer. This was particularly the case when a liquid-gel lubricant was being
used. However,
the slippery intermediate layer slides freely on fabric. Even when the fabric
is secured at the
perimeter, the central portion of the fabric still accommodates sliding
movement of the slippery
intermediate layer. It is important to note that the research conducted in
arriving at the above-
described helmet liner determined that only a limited movement of 5mm to 15mm
was
sufficient to dissipate some of the kinetic energy and reduce rotational
acceleration of the head.
[0007] If a greater range of movement is required to dissipate more kinetic
energy in an
intended application, there are a number of ways that this can be
accommodated. For example,
one could make the top fabric layer stretchable, such that the top fabric
layer facilitates
increased sliding movement of the slippery intermediate layer.
[0008] There are some immediate benefits in the use of the helmet liner, as
described
above. The helmet liners that use the liquid-gel lubricant are more difficult
and more expensive
to manufacture. More things can go wrong with helmet liners that use the
liquid-gel lubricant.
If the seal confining the liquid-gel lubricant is compromised, the liquid-gel
lubricant will leak
out or the liquid-gel lubricant will dry out when exposed to air. In either
event, movement of
the top layer in relation to the bottom layer was adversely affected.
[0009] In
all of the research, the helmet liner was attached to an interior surface of a
helmet
through the use of hoop and loop fasteners, commonly known by the Trademark
brand name
VELCRO fasteners. This attachment can be simplified when the top fabric layer
is capable of
serving as a loop portion of a hook and loop fastener and mates with a hook
portion of the hook
and loop fastener. The use of hook and loop fasteners actually improves the
performance of
the helmet liner when the top fabric layer serves as the loop portion of the
hook and loop
fastener. The hook portion anchors the top fabric layer which tends to
localize the impact force
(thus the sliding motion) and also ensures the sliding motion happens
optimally in specific
locations on the liner.
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Date Recue/Date Received 2021-05-28
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] These and other features will become more apparent from the
following description
in which reference is made to the appended drawings, the drawings are for the
purpose of
illustration only and are not intended to be in any way limiting, wherein:
[0011] FIG. 1 is atop plan view of a helmet liner.
[0012] FIG. 2 is a side elevation view, in section, of the helmet liner
of FIG. 1.
DETAILED DESCRIPTION
[0013] A helmet liner generally identified by reference numeral 10, will
now be described
with reference to FIG. 1 and FIG. 2.
Structure and Relationship of Parts:
[0014] Referring to FIG. 1, helmet liner 10 has a liner body 12.
Referring to FIG. 2, when
viewed in section, it can be seen that liner body 12 has an impact absorbing
bottom layer 14, a
slippery intermediate layer 16 and a top fabric layer 18. Slippery
intermediate layer 16 overlies
and is secured to bottom layer 14. Top fabric layer 18 overlies slippery
intermediate layer 16.
[0015] Referring to FIG. 2, top fabric layer 18 has a perimeter 20 and a
central portion 22.
Top fabric layer 18 is secured to either bottom layer 14, slippery
intermediate layer 16, or both
only at locations along perimeter 20. This leaves central portion 22 of top
fabric layer 18 free
to accommodate relating sliding movement of slippery intermediate layer 16. In
order to suit
most applications, a sliding movement of at least * must be achieved. Some
fabrics are
inherently more "slippery" and more readily accommodate sliding movement than
other
fabrics. The selection of the fabric material for top fabric layer 18 can,
therefore, impact
performance. Where increased sliding movement is desired, a stretchable fabric
material may
be selected for top fabric layer 18. This enables top fabric layer 18 to
facilitate increased sliding
movement of slipper intermediate layer 16 as top fabric layer 18 stretches.
[0016] Referring to FIG. 2, it is preferred that top fabric layer 18 is
being capable of serving
as a loop portion of a hook and loop fastener and mating with a hook portion
100 of the hook
and loop fastener for the purpose of connecting to an interior surface 102 of
a helmet 104.
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Date Recue/Date Received 2021-05-28
[0017] After experimenting with various fabric materials looking for a
fabric that is
slippery, provides the desired amount of movement and is capable of serving as
a loop portion
of a hook and loop fastener, nylon and spandex blend fabrics and polyester and
spandex blend
fabrics were found to provide beneficial results.
[0018] There are various materials that are suitable for impact absorbing
bottom layer 14.
The preferred material used during testing was a polymer foam and, more
particularly, an open
celled polymer foam. It will be appreciated that there are elastic materials
and auxetic materials
that would also be suitable.
[0019] There are various materials that are suitable for slippery
intermediate layer 16. The
preferred material used during testing was a polymer plastic and, more
particularly, a
thermoplastic.
[0020] Referring to FIG. 2, it was preferred that bottom layer 14 not be
placed in direct
contact with a human head. For that reason, a second fabric layer 24 was
adhered to bottom
layer 14. Second fabric layer 24 is for the comfort of the wearer and does not
contribute to
performance of helmet liner 10 in the event of an impact.
Operation:
[0021] Referring to FIG 2, in the event of an impact, interior surface
102 of helmet 104
will commence movement in a direction indicated by arrow 106 and then will
come to an
abrupt stop upon impact. A head 108 of a wearer will have commenced movement
in the
direction indicated by arrow 106. Helmet liner 10 protects head 108 of wearer
by dissipating
kinetic energy. Top fabric layer 18 is anchored to interior surface 102 of
helmet 104 by hook
portion 100 of a hook and loop fastener, which engages top fabric layer 18. As
previously
described, top fabric layer 18 serves as the loop portion of the hook and loop
fastener. Impact
absorbing bottom layer 14 with attached slippery intermediate layer 16 are
attached to head
108 of the wearer. However, there is relative sliding movement between
slippery intermediate
layer 16 and top fabric layer 18. This results in slippery intermediate layer
16 moving with
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Date Recue/Date Received 2021-05-28
head 108 and kinetic energy being absorbed by top fabric layer 18 which
remains stationary
with interior surface 102 of helmet 104.
Test Data:
[0022] Helmet impact tests were performed using a guided free-fall oblique
impact test rig
dropping a helmet against an anvil at an impact angle of 45 degrees. The
impact speed
generated was 6.5 meters per second. A test was first conducted with a helmet
having a
standard helmet liner. This established a base line for comparing the
performance of the
helmet line described above. Tests were conducted in five impact locations and
orientations:
1. front, 2. right side toward back, 3. left side toward back, 4. left side
toward front, and 5. right
side toward front. The rotational acceleration percentage reduction achieved
by helmet liner
10 was as follows: 1. front an improvement of 22%, 2. right side toward back
an improvement
of 35%, 3. left side toward back an improvement of 6%, 4. left side toward
front an
improvement of 31% and 5. right side toward front an improvement of 45%. It is
to be noted
that in orientation #3 that improvement gained was only 6%. The reason for
this is believed to
be due to the shape of the helmet tested, which created a geometric lock
reducing the amount
of motion possible.
[0023] In this patent document, the word "comprising" is used in its non-
limiting sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the elements is present, unless the context
clearly requires that
there be one and only one of the elements.
[0024] The scope of the claims should not be limited by the illustrated
embodiments set
forth as examples but should be given the broadest interpretation consistent
with a purposive
construction of the claims in view of the description as a whole.
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