Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 2750596 2017-02-23
PROTECTIVE HEADGEAR COMPRESSION MEMBER
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to protective headgear and other impact absorbing
structures. It
relates especially to an impact absorbing compression member for use therein.
Background Information
Headgear such as a helmet is often worn by individuals during games and other
physical
activities to help protect the wearers from head injury. Head injury can
result from impact forces
due to contact with other people or objects. Currently marketed helmets
generally fall into one of
two categories, i.e. single impact helmets or multiple impact helmets. Single
impact helmets
undergo permanent deformation under impact, whereas multiple impact helmets
are capable of
withstanding multiple blows. The wearers of single impact helmets include, for
example,
bicyclists and motorcyclists. On the other hand, participants in sports such
as hockey and football
and construction workers generally wear multiple impact helmets. Both
categories of helmets
have similar constructions which include a semi-rigid outer shell which
distributes the force of
an impact over a wide area, a crushable layer inside the shell which reduces
the force of the
impact on the wearer's head, and usually also an inner liner that helps to
shape the helmet to the
wearer's head. Invariably, such helmets also include a chin strap for securing
the helmet to the
wearer's head.
Recently, there has been developed a class of protective headgear
incorporating a
plurality of energy-absorbing layers. Such headgear is disclosed, for example,
in publications
W02006/089234 and W02006/089235 and US2007/0190292, published August 16, 2007.
As
seen there, such helmets include a semi-rigid outer layer or shell, an inner
layer and a middle
layer between the outer and inner layers. This middle layer is composed of a
plurality of
individual compressible cells disposed in a fluid-containing interstitial
region formed by the
inner and outer layers. At least one passageway is provided by which fluid can
leave the middle
layer as the outer layer deforms in response to an impact on the helmet. Such
helmets may also
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contain a dynamic inner liner whose shape can change to conform to a wearer's
head as each
helmet is drawn down on the head by the associated chin strap; see
W02006/089098.
As seen from the aforesaid publications, each impact absorbing cell of the
middle layer of
the helmet comprises at least one thin-walled enclosure having an uncompressed
configuration
which defines a hollow chamber, a volume of fluid at least partially filling
that chamber, at least
one orifice through the enclosure wall that resistably vents fluid from the
chamber in response to
an impact on the enclosure and an impact-absorbing mechanism associated with
the enclosure
that resists yielding in response to an initial phase of an impact on the
enclosure, and that yields
to the impact after the initial phase of the impact to allow the remainder of
the impact to be
managed by the fluid venting from the orifice. In a preferred protective
helmet, the dynamic
inner liner is composed of individual compressible elements positioned at the
cell locations and
whose shapes can change to conform to a wearer's head as the helmet is drawn
down on the head
by an associated chin strap assembly. Thus, each cell and the corresponding
compressible
element form a unitary compression member.
While the aforesaid protective helmets and structures employing such impact-
absorbing
compression members perform their impact-absorbing function quite well, the
total thickness of
the helmet layers is larger than might be desired. Also, the compressible
structures forming the
dynamic inner liner of the helmet are usually simply foam pads or capsules
adhered to the
underside of the associated cell and are prone to bottoming out when the
helmet is pressed
against the wearer's head by high impact forces, thus causing discomfort to
the wearer. Simply
increasing the thickness of the pads in an attempt to overcome this problem
results in an
undesirable increase in helmet size.
SUMMARY
Accordingly, it is desirable to provide a compression member in the nature of
a shock
absorber for providing the middle layer and liner of a helmet or other
protective structure.
It is further desirable to provide such a compression member which has minimal
overall
thickness, yet whose components do not tend to bottom out under the
compression forces
encountered during normal use of the member.
It is further desirable to provide a compression member of this type which is
relatively
easy to releasably attach to the inner layer of a helmet or other protective
structure.
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It is further desirable to provide such a compression member which when
incorporated
into a helmet along with a multiplicity of other similar members produces
headgear which is
comfortable to wear for a prolonged period even when the helmet is repeatedly
impacted from
without.
It is further desirable to provide such a compressible member composed of a
few molded
plastic parts which are relatively easy to assemble.
In an aspect, there is provided a compression member for a protective
structure, the
member comprising: a hollow, axially symmetric compression cell having a top
wall, a bowed
side wall and a bottom flange extending laterally out from the side wall, and
a plate that is co-
extensive with the flange position and against the underside of the flange,
the flange and plate
secured together at their peripheries; a liner element secured coaxially to
the cell, the liner
element including an axially flexible envelope with a bottom wall extending up
to an outer edge
of an annular shoulder that has an inner edge connected to a laterally
extending second flange
that is coextensive with the plate, the second flange being positioned against
the underside of the
plate and the second flange and plate being secured together at their
peripheries, and a resilient
material substantially filling the envelope.
Other features will, in part, be obvious and will, in part, appear
hereinafter. The invention
accordingly comprises the features of construction, combination of elements
and arrangement of
parts which will be exemplified in the following detailed description, and the
scope of the
invention will be indicated in the claims.
In general, an example protective helmet compression member includes a hollow,
axially
symmetric compression cell having an upper wall, a side wall and a flanged
bottom wall. The
compression member also includes a compressible liner element mounted to the
flange. This
element is composed of a hollow flexible envelope having a bottom wall and a
side wall
extending upwardly/inwardly from that bottom wall and connected to a radial
flange that is
secured flush to the cell flange. The envelope is substantially filled by one
or more resilient pads.
Preferably, the bottom wall of the cell inboard the cell flange is curved
upwardly, giving
the cell a dished or concave undersurface to provide additional clearance for
the pad(s). This
construction along with the pad(s) enables the compression member to withstand
appreciable
compression forces without the liner element bottoming out against the
underside of the cell.
Resultantly, when a multiplicity of the compression members are
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incorporated into a protective structure such as a football helmet, the
structure is comfort-
able to wear for a prolonged period, despite repeated impacts thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
For a further understanding of the nature and objects of the invention,
reference
should be made to the following detailed description taken in connection with
the accom-
panying drawings, in which:
FIG. 1 is a side elevational view of a protective helmet incorporating
compression
members in accordance with this invention;
FIG. 2 is a perspective view, on a larger scale, showing one of the
compression
io members of the FIG. 1 helmet in greater detail;
FIG. 3 is an exploded perspective view showing the components of the FIG. 2
compression member in greater detail, and
FIG. 4 is a sectional view taken along line 3-3 of FIG. 2.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIG. 1 of the drawings, compression members incorporating the in-
vention and indicated generally at 10 are shown incorporated into a protective
structure,
i.e., a football helmet H having an outer layer or shell shown in phantom at 0
and an in-
ner layer I. Members 10 are releasably secured to layer I. As described in the
above pub-
lications, shell 0 is of a relatively hard plastic material that deforms
locally and radially
in response to an impact, and the inner layer I may be of a softer, less rigid
material.
Each compression member 10 comprises a hollow, compressible, resilient cell 12
which extends between the inner and outer layers, and a compressible liner
element 14
located directly opposite cell 12 and which projects from the interior surface
of layer I.
Cells 12 collectively form a helmet middle layer in an interstitial region
between layers 0
and I and elements 14 collectively form a dynamic inner liner of the helmet.
As shown in FIG. 4, each member 10 is secured in a different opening P in
inner
layer I by capturing the edge of that opening P between the associated cell 12
and its liner
element 14. The inner layer I is somewhat elastic so that the member 10 may be
attached
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to layer I by forcing its cell 12 through opening P, whose edge then snaps
into a periph-
eral recess around the cell as will be described in detail later.
Each cell 12 comprises a top wall 22, a bowed side wall 24 composed of a pair
of
back-to-back frustoconically shaped segments 24a and 24b and a radial flange
26 extend-
s ing out from the free lower edge of the segment 24b, leaving a large
central opening
within the flange. A vent hole 27 is provided in top wall 22. In one working
example of
member 10 suitable for a football or motorcycle helmet, the top wall 22 has a
diameter of
1.9 in., the side wall 24 has a diameter of 2.0 in. at the equator with an
included angle 0
of 155 to 162 degrees between segments 24a and 24b, and the flange 26 has an
outer di-
n) ameter of 2.3 in. Cell 12 is of a material, e.g. TPU, which is
relatively stiff, yet allows
the cell as a whole to flex to provide the impact absorbing characteristics
described in the
above publications.
A plate 28 of the same material about 0.04 in. thick is positioned against the
un-
derside of the flange and the two are welded together at their edges to close
and complete
Is the bottom of the cell. Preferably a central area 28a of the plate is
domed or upwardly
curved (about 0.08 in. deflection) to conform to a typical head curvature for
reasons to be
described later. Also, a circular step or wall 28b may be provided on the
upper surface of
the plate to center the cell on the plate.
As shown in FIGS. 2 and 3, the liner element 14 is coaxial to cell 12 and has
more
zo or less the same footprint as the cell. Instead of being a simple
compressible bellows
capsule or pad as described in the above publications, each element 14 is a
composite
structure which includes a cup-like hollow envelope or membrane 32, a first,
soft resilient
pad 34 and a second, smaller, denser resilient pad 36.
Envelope 32 is of a flexible plastic material such as TPU. It has a circular
bottom
25 wall 38 with a gently rounded edge margin 38a which extends up to the
radially outer
edge of a relatively stiff annular shoulder 42. The inner edge of shoulder 42
connects to a
short, e.g. 0.06 in., upstanding neck 44 whose upper end transitions to a
radially outer
flange 46. The outer diameter of flange 46 is substantially the same as that
of flange 26
and plate 28 of cell 12.
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In accordance with the invention, the bottom wall 38, 38a of envelope 32,
while
strong, is also quite thin and flexible, whereas the envelope shoulder, neck
and flange
have thicker walls so that they are individually relatively stiff. In the
above working ex-
ample, the wall 38, 38a has a thickness of 0.02 inch and the shoulder, neck
and flange
have wall thicknesses of 0.02, 0.03 and 0.03 inch, respectively. In the above
example of
member 10, the overall height of the liner element is in the order of 0.33
inch.
As best seen in FIGS. 3 and 4, the pad 34 is die cut of a foam material, e.g.
open
cell polyurethane foam of density 18 to 15 lb./cu.ft. and its diameter, e.g.
2.05 in., and
thickness, e.g. 0.28 in., are such that the pad can fit within the confines of
envelope bot-
tom wall 38, 38a.
On the other hand, the smaller pad 36 is die cut of a stiffer plastic foam
material,
e.g. vinyl nitrile 602 having a density 17 to 25 lb./cu.ft. and its diameter,
e.g. 1.4 in., and
thickness, e.gØ20 in., are such as to enable that pad to fit within the neck
44 of envelope
32 between pad 36 and plate 28. The pads 34 and 36 are die cut in the circular
shapes
shown in FIG. 3, not FIG. 4. They assume the shapes shown in FIG. 4 when the
enve-
lope or membrane 38, 38a is installed around them.
To assemble the liner element 14 to cell 12, the pad 34 is inserted into
envelope
32 so that it is flush against bottom wall 38. Then, pad 36 is positioned
against the un-
derside of plate portion 28a within neck 44. To hold pad 36 in place during
assembly, an
zo adhesive or double sided tape (not shown) may be interposed between pad
36 and the
plate portion 28a. Finally, the flange 46 of envelope 32 and the flange 26 of
cell 12 are
positioned together coaxially and welded or otherwise secured together as
shown at 50 in
FIG. 4. This leaves the shoulder 42 and neck 44 free to flex in the axial
direction.
Preferably, the thickness of pad 36 is such that when the two flanges are
secured
together at 50, the two pads 34 and 36 substantially fill the space between
the plate 28
and bottom wall 38, 38a so that the underside of the liner element 14
constitutes a soft
pillow that conforms to the shape of any surface contacting that wall. The
fact that the
liner element 14 is movable axially relative to cell 12 and the presence of
the pads mini-
mize the likelihood of the liner element 14 bottoming out should that element
be sub-
jected to high compression forces due to impacts to helmet H (FIG. 1) when the
helmet is
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on a wearer's head. That the central portion 28a of plate 28, i.e. the area
thereof within the cell
12, is upwardly curved or dished as described above also helps in this respect
in that it provides
additional clearance between the plate and a wearer's head without increasing
the overall height
of the compression member 10. This height is typically in the order of 2.0 in.
for a cell 10 used in
a helmet. That height may me as small as 1.0 in. when the cell is used in
other applications, e.g.
as a jaw shock absorber.
When a player dons the helmet H, the composite liner element 14 of each
compression
member 10 conforms to the wearer's head resulting in a very comfortable fit of
the helmet to the
head. Yet, each member 10 still has a relatively low profile within helmet H
so that the helmet is
no larger than a conventional helmet that does not incorporate the members 10.
Finally, because
of the aforesaid composite construction of the liner element 14, that element
is not likely to
bottom out during normal use of the helmet.
It will thus be seen that the features set forth among those made apparent
from the
preceding description above can be efficiently attained in embodiments
disclosed herein. Also,
certain changes may be made in the construction described above without
departing from the
scope of the invention. For example, although the cell 12 of the compression
member 10
specifically described has a circular cross section, other cell shapes are
possible so long as the
edges of the cell form a symmetrical shape that passes through a specific set
of points arranged
in a specific pattern as described in the above US2007/0190292 and the liner
element 14 has
more or less the same footprint as the cell flange. Also, instead of forming
pads 34, 36 as
separate elements, they may be formed as a unit with a varying density or as a
collection of
resilient particles. Therefore, it is intended that all matter contained in
the above description or
showing in the accompanying drawings be interpreted as illustrative and not in
a limiting sense.
It is also understood that the following claims are intended to cover all of
the generic and
specific features of the invention described herein.
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