U.S. patent application number 11/059427 was filed with the patent office on 2006-03-23 for multilayer air-cushion shell with energy-absorbing layer for use in the construction of protective headgear.
This patent application is currently assigned to Xenith Athletics, Inc.. Invention is credited to Vincent R. Ferrara.
Application Number | 20060059606 11/059427 |
Document ID | / |
Family ID | 35447767 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060059606 |
Kind Code |
A1 |
Ferrara; Vincent R. |
March 23, 2006 |
Multilayer air-cushion shell with energy-absorbing layer for use in
the construction of protective headgear
Abstract
A multilayer shell for use in the construction of protective
headgear, the shell including an outer layer, an inner layer, and a
middle layer disposed between the outer and inner layer which
resiliently compresses in response to an impact to the outer layer.
The middle layer includes a plurality of compressible members,
which resiliently compress to absorb the energy of a direct impact
to the outer layer and resiliently shear with respect to the inner
layer in response to a tangential impact to the outer layer. Each
of the of compressible members may have bellows-like construction
which forms a hollow chamber and includes a small opening through
which air is expelled to produce a rate-sensitive response
corresponding to the force of the impact. The shell may include one
or more passageways to expel air from the middle layer into the
interior of the headgear during and as a result of an impact.
Inventors: |
Ferrara; Vincent R.;
(Wellesley, MA) |
Correspondence
Address: |
CESARI AND MCKENNA, LLP
88 BLACK FALCON AVENUE
BOSTON
MA
02210
US
|
Assignee: |
Xenith Athletics, Inc.
Boston
MA
|
Family ID: |
35447767 |
Appl. No.: |
11/059427 |
Filed: |
February 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10946672 |
Sep 22, 2004 |
|
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11059427 |
Feb 16, 2005 |
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Current U.S.
Class: |
2/412 ;
2/410 |
Current CPC
Class: |
A42B 3/064 20130101;
A01N 25/34 20130101; A42B 3/121 20130101; A42B 3/066 20130101; A01N
25/18 20130101; A42B 3/12 20130101; A01N 25/20 20130101 |
Class at
Publication: |
002/412 ;
002/410 |
International
Class: |
A42B 3/00 20060101
A42B003/00 |
Claims
1. Protective headgear, comprising: an outer layer having an
internally surface; an inner layer having a surface that faces the
outer layer; a middle layer having a plurality of compressible
members disposed in a fluid-containing interstitial region formed
by the inner and outer layers; and at least one passageway by which
fluid can leave the middle layer as the outer layer deforms in
response to an impact on the outer layer.
2. The protective headgear of claim 1, wherein the at least one
passageway includes a gap between a peripheral edge of the outer
layer and a peripheral edge of the inner layer to permit fluid to
exit the interstitial region in response to an impact.
3. The protective headgear of claim 1, wherein the at least one
passageway includes an opening in the inner layer.
4. The protective headgear of claim 3, wherein fluid that passes
through the opening in the inner layer is felt by a wearer of the
protective headgear.
5. The protective headgear of claim 1, wherein at least one of the
compressible members is made of thermoplastic elastomer (TPE)
material.
6. The protective headgear of claim 5, wherein the TPE material is
a TPE foam.
7. The protective headgear of claim 1, wherein at least one of the
compressible members is a columnar in shape.
8. The protective headgear of claim 1, wherein at least one of the
compressible members includes a chamber for holding a volume of
fluid, and the chamber includes a chamber surface having a chamber
opening for the passage of fluid into and out of the chamber.
9. The protective headgear of claim 8, wherein the chamber opening
is adapted to produce a rate-sensitive response to the force of the
impact exerted on the outer layer.
10. The protective headgear of claim 8, wherein at least one
compressible member expels fluid from the chamber through the
chamber opening when the compressible member is compressed by the
force of the impact and expands to draw fluid back into the chamber
as the compressive force exerted on the outer layer is
mitigated.
11. The protective headgear of claim 8, wherein the chamber is
aligned with an opening in the inner layer to enable the passage of
fluid through the inner layer.
12. The protective headgear of claim 1, wherein the inner layer
includes an internal surface, and the headgear further comprising a
compressible internal liner disposed inwardly of the internal
surface of the inner layer.
13. The protective headgear of claim 1, wherein at least one
compressible member includes a chamber for holding a volume of
fluid, and the chamber includes a chamber surface having at least
one chamber opening for passing fluid into and from the
interstitial region formed by the outer and inner layers.
14. The protective headgear of claim 1, further comprising a
resilient attachment for resiliently attaching and maintaining the
orientation of the outer layer with respect to the inner layer.
15. The protective headgear of claim 1, wherein the outer layer
shears rotationally with respect to the inner layer as the outer
layer deforms in response to the impact.
16. A method for making protective headgear, the method comprising
the steps of: forming a multilayered shell by: forming a plurality
of individually compressible members; providing an outer layer and
a inner layer; and producing a composite structure wherein the
compressible members are disposed in an fluid-containing
interstitial region formed by the outer and inner layers, such that
the outer layer deforms and the compressible members
correspondingly compress in response to an impact to the outer
layer.
17. The method of claim 16, wherein at least one compressible
member is formed of thermoplastic elastomer material.
18. The method of claim 17, further comprising the step of:
introducing a chemical foaming agent into the thermoplastic
elastomer material to produce compressible members made of
thermoplastic elastomer foam.
19. The method of claim 16, further comprising the step of: forming
at least one of the compressible members to include a chamber for
holding a volume of fluid, the chamber defining a chamber surface
having at least one chamber opening for the passage of fluid into
and out of the chamber.
20. The method of claim 19, further comprising the step of:
releasing fluid through the at least one chamber opening into the
interstitial region formed by the inner and outer layers as the
outer layer deforms in response to the impact to the outer
layer.
21. The method of claim 19, further comprising the step of:
aligning the at least one chamber opening with an opening of the
inner layer; and releasing fluid through the at least one chamber
opening toward the head of a wearer as the outer layer deforms in
response to an impact to the outer layer.
22. The method of claim 16, wherein the producing step is such that
the outer layer shears rotationally with respect to the inner layer
in response to the impact.
23. The protective headgear of claim 1, wherein the outer layer
includes an internal surface, the inner layer includes a surface
that faces the outer layer and at least one of the plurality of
compressible members is attached to at least one of the internal
surface of the outer layer and the surface of the inner layer that
faces the outer surface.
24. The method of claim 16, wherein the outer layer includes an
internal surface, the inner layer includes a surface that faces the
outer layer and the method further comprises the step of: attaching
at least one of the plurality of compressible members to at least
one of the internal surface of the outer layer and the surface of
the inner layer that faces the outer layer.
25. Protective headgear, comprising: a relatively thin outer layer
having an outwardly facing surface; a relatively thin inner layer
having an area which is spaced apart from the outer layer; and a
middle layer disposed in an area formed by the outer layer and the
inner layer, the middle layer comprising a plurality of
compressible members; the middle layer being adapted to resiliently
compress in response to a bending deformation of the outer layer to
absorb energy of an impact; and the outer layer being adapted to
shear with respect to the inner layer in response to a tangential
component of the impact to the outer layer.
26. The protective headgear of claim 25, wherein the outwardly
facing surface of the outer layer is relatively smooth to reduce
the tangential component of the impact.
27. The protective headgear of claim 25, further comprising a
relatively compressible inner liner disposed inwardly of the inner
layer.
28. The protective headgear of claim 25, wherein the middle layer
has a rebound resilience elasticity of about fifty percent (50%) or
less.
29. The protective headgear of claim 28, wherein the middle layer
has a rebound resilience elasticity of about twenty-five percent
(25%) or less.
30. The protective headgear of claim 25, wherein the plurality of
compressible members are disposed in a fluid-containing
interstitial region bounded by the outer layer and the inner
layer.
31. The protective headgear of claim 25, wherein the outer layer
includes an internally facing surface and at least one of the
compressible members of the middle layer is attached to at least
one of a surface of the inner layer that faces the outer layer and
the internally facing surface of the outer layer.
32. The protective headgear of claim 25, further comprising at
least one passageway for passing fluid from the middle layer in
response to the impact.
33. The protective headgear of claim 32, wherein the at least one
passageway includes a gap between the outer layer and the inner
layer.
34. The protective headgear of claim 32, wherein the at least one
passageway includes at least one opening in the inner layer.
35. The protective headgear of claim 25, wherein at least one of
the compressible members includes walls which define a
fluid-containing internal chamber and the walls include at least
one opening to permit fluid to exit the internal chamber in
response to the impact.
36. The protective headgear of claim 25, wherein at least one of
the compressible members has a bellows-like sidewall
construction.
37. The protective headgear of claim 35, wherein the walls of the
compressible member have a bellows-like sidewall construction to
facilitate compression of the compressible member in response to
the impact.
38. The protective headgear of claim 35, wherein the at least one
opening in the walls of the compressible member is adapted to
produce a rate-sensitive response to the force of the impact
exerted on the outer layer such that the compressible member
compresses with relatively little resistance when the impact is of
relatively low energy and such that the compressible member
compresses with relatively high resistance when the impact force is
of relatively high energy.
39. The protective headgear of claim 38, wherein the at least one
opening in the walls of the compressible member is adapted such
that, when the impact is of relatively high energy, the
compressible member compresses with sufficiently high resistance to
convert energy of the impact to heat in the compressible
member.
40. The protective headgear of claim 25, wherein at least one of
the compressible members of the middle layer compresses in response
to the bending deformation of the outer layer and resiliently
shears with respect to the inner layer in response to the
tangential impact component.
41. The protective headgear of claim 25, wherein the compressible
members of the middle layer have a honeycomb structure of
interconnected cells.
42. The protective headgear of claim 25, wherein the compressible
members of the middle layer are arranged in a pre-determined
pattern between the outer layer and the inner layer.
43. The protective headgear of claim 41, wherein the interconnected
cells of the honeycomb-structured middle layer are arranged in a
pre-determined pattern between the outer layer and the inner
layer.
44. The protective headgear of claim 25, wherein the compressible
members are made of thermoplastic elastomer (TPE) material.
45. The protective headgear of claim 44, wherein the TPE material
is a TPE foam.
46. The protective headgear of claim 44, wherein the TPE material
has a glass-transition temperature less than about minus twenty
degrees (-20.degree.) Fahrenheit.
47. The protective headgear of claim 41, wherein the
honeycomb-structured middle layer is made of a thermoplastic
elastomer (TPE) material.
48. The protective headgear of claim 47, wherein the TPE material
is a TPE foam.
49. The protective headgear of claim 47, wherein the TPE material
has a glass-transition temperature less than about minus twenty
degrees (-20.degree.) Fahrenheit.
50. The protective headgear of claim 35, wherein the at least one
opening in the at least one compressible member permits fluid to
enter the internal chambers thereof as the compressible member
resiliently expands as the force of the impact is mitigated.
51. The protective headgear of claim 35, wherein the inner layer
includes at least one opening in communication with the least one
opening in the at least one compressible member to permit fluid
exiting from the at least one compressible member when compressed
to pass through the inner layer.
52. The protective headgear of claim 35, further comprising a
relatively compressible inner liner layer disposed inwardly of the
inner layer and wherein the inner layer and the inner liner layer
include at least one opening in communication with the least one
opening in the at least one compressible member to permit fluid
exiting from the compressible member when compressed to pass
through the inner layer and the inner liner layer.
53. The protective headgear of claim 25, wherein the compressible
members are independent of one another.
54. The protective headgear of claim 25, wherein the compressible
members are interconnected.
55. The protective headgear of claim 25, wherein the inner layer is
of a relatively rigid thermoplastic material.
56. The protective headgear of claim 25, wherein the outer layer is
of a thermoplastic material.
57. The protective headgear of claim 56, wherein the thickness of
the thermoplastic material of the outer layer is such that the
outer layer resiliently deforms by bending inwardly in response to
the impact.
58. The protective headgear of claim 25, wherein the bending
deformation of the outer layer and the compression of compressible
members of the middle layer in response to the impact combine to
reduce linear changes of velocity of a wearer's head due to the
impact.
59. The protective headgear of claim 25, wherein the shearing of
the outer layer with respect to the inner layer and of the
compressible members of the middle layer in response to the impact
combine to reduce rotational changes of velocity of the wearer's
head due to the impact.
60. The protective headgear of claim 25, wherein the outer layer
includes a plurality of ventilation openings.
61. Impact absorbing protective headgear, comprising an inner
layer; an outer layer, the inner and outer layers having opposed
surfaces; and a middle layer comprising a plurality of compressible
members, the middle layer extending between the inner and outer
layers the inner and outer layers being at least partially
coextensive so that when the outer layer is impacted, the outer
layer deflects locally in response to the impact, thereby absorbing
at least some of the energy created by the impact, and at least one
of the compressible members of the middle layer compresses and
shears relative to the inner layer to absorb impact energy not
absorbed by the outer layer.
62. The protective headgear of claim 61, wherein the middle layer
is anchored in at least one location to the opposed surfaces of the
inner layer and the outer layer, the inner and outer layers being
at least partially coextensive.
63. The protective headgear of claim 61, wherein the outer layer
comprises an outwardly facing surface and the outwardly facing
surface of the outer layer is relatively smooth to reduce the
tangential component of the impact.
64. The protective headgear of claim 61, further comprising a
relatively compressible inner liner layer disposed inwardly of the
inner layer.
65. The protective headgear of claim 61, wherein the middle layer
has a rebound resilience elasticity of about fifty percent (50%) or
less.
66. The protective headgear of claim 65, wherein the middle layer
has a rebound resilience elasticity of about twenty-five percent
(25%) or less.
67. The protective headgear of claim 61, wherein the plurality of
compressible members are disposed in a fluid-containing
interstitial region bounded by the outer layer and the inner
layer.
68. The protective headgear of claim 61, wherein at least one of
the compressible members of the middle layer is attached to a
surface of the inner layer that faces the outer layer and to an
internally facing surface of the outer layer.
69. The protective headgear of claim 61, further comprising at
least one passageway by which fluid can leave the middle layer in
response to the impact.
70. The protective headgear of claim 69, wherein the at least one
passageway includes a gap between the outer layer and the inner
layer.
71. The protective headgear of claim 69, wherein the at least one
passageway includes at least one opening in the inner layer.
72. The protective headgear of claim 61, wherein at least one of
the compressible member includes walls which define a
fluid-containing internal chamber and the walls include at least
one opening to permit fluid to exit the internal chamber in
response to the impact.
73. The protective headgear of claim 61, wherein at least one of
the compressible members has a bellows-like sidewall
construction.
74. The protective headgear of claim 72, wherein the walls of the
at least one compressible member has a bellows-like sidewall
construction which facilitates compression of the compressible
member in response to the impact.
75. The protective headgear of claim 72, wherein the at least one
opening in the walls of the compressible member is adapted to
produce a rate-sensitive response to the force of the impact
exerted on the outer layer such that the compressible member
compresses with relatively little resistance when the impact is of
relatively low energy and such that the compressible member
compresses with relatively high resistance when the impact force is
of relatively high energy.
76. The protective headgear of claim 75, wherein the at least one
opening in the walls of the compressible member is adapted such
that, when the impact is of relatively high energy, the
compressible member compresses with sufficiently high resistance to
convert energy of the impact to heat in the compressible
member.
77. The protective headgear of claim 61, wherein the middle layer
has a honeycomb structure of interconnected cells.
78. The protective headgear of claim 61, wherein the compressible
members of the middle layer are arranged in a pre-determined
pattern between the outer layer and the inner layer.
79. The protective headgear of claim 77, wherein the interconnected
cells of the honeycomb-structured middle layer are arranged in a
pre-determined pattern between the outer layer and the inner
layer.
80. The protective headgear of claim 61, wherein the compressible
members are made of thermoplastic elastomer (TPE) material.
81. The protective headgear of claim 80, wherein the TPE material
is a TPE foam.
82. The protective headgear of claim 80, wherein the TPE material
has a glass-transition temperature less than about minus twenty
degrees (-20.degree.) Fahrenheit.
83. The protective headgear of claim 77, wherein the
honeycomb-structured middle layer is made of a thermoplastic
elastomer (TPE) material.
84. The protective headgear of claim 83, wherein the TPE material
is a TPE foam.
85. The protective headgear of claim 83, wherein the TPE material
has a glass-transition temperature less than about minus twenty
degrees (-20.degree.) Fahrenheit.
86. The protective headgear of claim 72, wherein the at least one
opening in the compressible member permits fluid to be drawn into
the internal chamber thereof as the compressible member resiliently
expands in response to mitigation of the force of the impact.
87. The protective headgear of claim 72, wherein the inner layer
includes at least one opening in communication with the at least
one opening in the compressible member to permit fluid exiting from
the compressible member when compressed to pass through the inner
layer.
88. The protective headgear of claim 72, wherein the outer layer
includes at least one opening in communication with the at least
one opening in the compressible member to permit fluid exiting from
the compressible member when compressed to pass through the outer
layer.
89. The protective headgear of claim 72, further comprising a
relatively compressible inner liner layer disposed inwardly of the
inner layer and wherein the inner layer and the inner liner layer
include at least one opening in communication with the at least one
opening in the compressible member to permit fluid exiting from the
compressible member when compressed to pass through the inner layer
and the inner liner layer.
90. The protective headgear of claim 61, wherein the compressible
members are independent of one another.
91. The protective headgear of claim 61, wherein the compressible
members are interconnected.
92. The protective headgear of claim 91, wherein a first end of at
least one of the compressible members is attached to the outer
layer and a second end of the at least one compressible members is
attached to the inner layer.
93. The protective headgear of claim 61, wherein the inner layer is
of a relatively rigid thermoplastic material.
94. The protective headgear of claim 61, wherein the outer layer is
of a thermoplastic material.
95. The protective headgear of claim 94, wherein the thickness of
the thermoplastic material of the outer layer is such that the
outer layer resiliently deforms by bending inwardly in response to
the impact.
96. The protective headgear of claim 61, wherein the bending
deformation of the outer layer and the compression of the middle
layer in response to the impact combine to reduce linear changes of
velocity of a wearer's head due to the impact.
97. The protective headgear of claim 61, wherein the shearing of
the outer layer with respect to the inner layer and the compression
of the middle layer in response to the impact combine to reduce
rotational changes of velocity of the wearer's head due to the
impact.
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part application
claiming priority to co-pending U.S. patent application Ser. No.
10/946,672, filed Sep. 22, 2004, titled "Layered Construction of
Protective Headgear with one or More Compressible Layers of
Thermoplastic Material," the entirety of which patent application
is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention relates generally to protective headgear. More
specifically, the invention relates to a layered construction of
protective headgear using compressible materials.
BACKGROUND
[0003] Concussions, also called mild traumatic brain injury, are a
common, serious problem in sports known to have detrimental effects
on people in the short and long term. With respect to athletes, a
concussion is a temporary and reversible neurological impairment,
with or without loss of consciousness. Another definition for a
concussion is a traumatically induced alteration of brain function
manifested by 1) an alteration of awareness or consciousness, and
2) signs and symptoms commonly associated with post-concussion
syndrome, such as persistent headaches, loss of balance, and memory
disturbances, to list but a few. Some athletes have had their
careers abbreviated because of concussions, in particular because
those who have sustained multiple concussions show a greater
proclivity to further concussions and increasingly severe symptoms.
Although concussions are prevalent among athletes, the study of
concussions is difficult, treatment options are virtually
non-existent, and "return-to-play" guidelines are speculative.
Accordingly, the best current solution to concussions is prevention
and minimization.
[0004] Concussion results from a force being applied to the brain,
usually the result of a direct blow to the head, which results in
shearing force to the brain tissue, and a subsequent deleterious
neurometabolic and neurophysiologic cascade. There are two primary
types of forces experienced by the brain in an impact to the head,
linear acceleration and rotational acceleration. Both types of
acceleration are believed to be important in causing concussions.
Decreasing the magnitude of acceleration thus decreases the force
applied to the brain, and consequently reduces the risk or severity
of a concussion.
[0005] Protective headgear is well known to help protect wearers
from head injury by decreasing the magnitude of acceleration (or
deceleration) experienced by their wearers. Currently marketed
helmets, primarily address linear forces, but generally do not
diminish the rotational forces experienced by the brain. Helmets
fall generally into two categories: single-impact helmets and
multiple-impact helmets. Single-impact helmets undergo permanent
deformation under impact, whereas multiple-impact helmets are
capable of sustaining multiple blows. Applications of single-impact
helmets include, for example, bicycling and motorcycling.
Participants of contact sports, such as hockey and football, use
multiple-impact helmets. Both categories of helmets have similar
construction. A semi-rigid outer shell distributes the force of
impact over a wide area and a crushable inner layer reduces the
force upon the wearer's head.
[0006] The inner layer of single-impact helmets are typically
constructed of fused expanded polystyrene (EPS), a polymer
impregnated with a foaming agent. EPS reduces the amount of energy
that reaches the head by permanently deforming under the force of
impact. To be effective against the impact, the inner layer must be
sufficiently thick not to crush entirely throughout its thickness.
A thick inner layer, however, requires a corresponding increase in
the size of the outer shell, which increases the size and bulkiness
of the helmet.
[0007] Inner layers designed for multiple-impact helmets absorb
energy through elastic and viscoelastic deformation. To absorb
multiple successive hits, these helmets need to rebound quickly to
return to their original shape. Materials that rebound too quickly,
however, permit some of the kinetic energy of the impact to
transfer to the wearer's head. Examples of materials with positive
rebound properties, also called elastic memory, include foamed
polyurethane, expanded polypropylene, expanded polyethylene, and
foamed vinylnitrile. Although some of these materials have
desirable rebound qualities, an inner layer constructed therefrom
must be sufficiently thick to prevent forceful impacts from
penetrating its entire thickness. The drawback of a thick layer, as
noted above, is the resulting bulkiness of the helmet. Moreover,
the energy-absorbing properties of such materials tend to diminish
with increasing temperatures, whereas the positive rebound
properties diminish with decreasing temperatures. There remains a
need, therefore, for an improved helmet construction that can
reduce the risk and severity of concussions without the
aforementioned disadvantages of current helmet designs.
SUMMARY
[0008] In one aspect, the invention features protective headgear
comprising an outer layer having an internally facing surface, an
inner layer having a surface that faces the outer layer, and a
middle layer having a plurality of compressible members disposed in
a fluid-containing interstitial region bounded by the inner and
outer layers. Each compressible member is attached to the surface
of the inner layer and to the internally facing surface of the
outer layer. The protective headgear also has at least one
passageway by which fluid can leave the middle layer when the
protective headgear experiences an impact.
[0009] In another aspect, the invention features a method for
making protective headgear comprising forming a multi-layered shell
by forming a plurality of individually compressible members,
providing an outer layer and a inner layer, and producing a
composite structure with the individually compressible members
being disposed in an interstitial region bounded by the outer and
inner layers, each compressible member being attached to an
internally facing surface of the outer layer and to a surface of
the inner layer facing the outer layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and further advantages of this invention may be
better understood by referring to the following description in
conjunction with the accompanying drawings, in which like numerals
indicate like structural elements and features in various figures.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating the principles of the invention.
[0011] FIG. 1 is a side view of an embodiment of a helmet
constructed in accordance with the present invention.
[0012] FIG. 2 is a cross-sectional view of the helmet of FIG. 1
showing an embodiment of a layered construction having a hard inner
layer disposed between a compressible internal layer and a middle
layer.
[0013] FIG. 3 is a side view of another embodiment of a helmet
constructed in accordance with the present invention.
[0014] FIG. 4 is a cross-sectional view of another embodiment of a
layered construction for protective headgear embodying the
invention, the embodiment having a multilayer shell with a
plurality of compressible members disposed between an outer surface
and an inner surface.
[0015] FIG. 5 is a diagram illustrating an embodiment of a
simplified manufacturing schematic for forming a multi-layer shell
for use, for example, in constructing protective headgear.
[0016] FIG. 6 is a diagram illustrating an embodiment of a
simplified manufacturing schematic for adding an internal liner to
the multilayer shell of FIG. 5.
[0017] FIG. 7A is a diagram illustrating the operation of
protective headgear of the invention during a direct impact.
[0018] FIG. 7B is a diagram illustrating the operation of
protective headgear of the invention during a tangential
impact.
[0019] FIG. 8A is a diagram of an embodiment of a compressible
member having a hollow chamber for holding a volume of fluid.
[0020] FIG. 8B is a diagram of a sequence illustrating simulated
effects of a high-energy impact to the compressible member of FIG.
8A.
[0021] FIGS. 8C and 8D are diagrams illustrating the stretching and
bending capabilities of the compressible member of FIG. 8A.
[0022] FIG. 8E is a diagram of the compressible member of FIG. 8A
when compressed.
[0023] FIG. 9A is a diagram of another embodiment of a compressible
member with a hollow chamber for holding a volume of fluid.
[0024] FIG. 9B is cross-sectional view of an embodiment of a shell
having openings formed in the outer and inner layers thereof for
the passage of fluid.
[0025] FIG. 10A is a cross-sectional view of an embodiment of a
shell having an outer shell, an inner layer, and a plurality of
compressible members disposed therebetween.
[0026] FIG. 10B is a diagram illustrating the shell of FIG. 10A on
a wearer's head.
[0027] FIG. 10C is a diagram illustrating the operation of
protective headgear of FIG. 10A during a direct impact.
[0028] FIG. 10D is a diagram illustrating the operation of
protective headgear of FIG. 10A during a tangential impact.
[0029] FIG. 11A is a rear view of an embodiment of protective
headgear employing compressible members of FIG. 9A.
[0030] FIG. 11B is a cross-sectional view of an embodiment of a
shell having an outer shell, an inner layer, and a plurality of
compressible members disposed therebetween.
DETAILED DESCRIPTION
[0031] The present invention relates to protective headgear
designed to lessen the amount of force that reaches the brain of
the wearer from an impact to the head. The headgear has a shell
with a multilayer construction for cushioning the impact, thus
slowing the change in velocity of the wearer's head, producing a
corresponding decrease in the magnitude of acceleration or
deceleration experienced by the wearer, and reducing the risk or
severity of concussion. As described further below, the shell has
an outer layer, an energy-absorbing layer, and an inner layer, with
one or more of these layers being constructed of an
energy-absorbing compressible material. In a preferred embodiment,
this compressible material is a thermoplastic elastomer (TPE).
[0032] Various embodiments of the energy-absorbing layer of the
shell function to provide an air cushion during an impact to the
headgear. In a preferred embodiment, an impact causes air to be
expelled from the energy-absorbing layer. Protective headgear of
the invention can respond to an impact by moving in any one or
combination of ways, including (1) globally compressing over a
broad area of the shell, (2) locally compressing at the point of
impact, (3) flexing by the outer layer of the shell, and (4)
rotating by the outer layer and the energy-absorbing layer with
respect to the inner layer.
[0033] The layered construction of the invention can be used to
construct a variety of types of protective headgear including, but
not limited to, safety helmets, motorcycle helmets, bicycle
helmets, ski helmets, lacrosse helmets, hockey helmets, and
football helmets, batting helmets for baseball and softball,
headgear for rock and mountain climbers, and headgear for boxers.
Other applications can include helmets used on construction sites,
in defense and military applications, and for underground
activities. Although the following description focuses primarily on
protective headgear, it is to be understood that the layered
construction of the invention applies to other types of equipment
used for sports activities or for other applications, e.g., face
masks, elbow pads, shoulder pads, and shin pads.
[0034] FIG. 1 shows a side view of an embodiment of a helmet 2
constructed in accordance with the invention. Here, the helmet 2
has an aerodynamic shape designed for use by bicyclists. This shape
is merely exemplary; it is to be understood that the helmet shape
can vary, depending upon the particular sporting event or activity
for which the helmet is designed. Further, helmets of the invention
can be constructed with various additional features, such as a cage
for a hockey helmet, a face mask for a football helmet, a visor for
a motorcycle helmet, retention straps, chin straps, and the
like.
[0035] The helmet 2 has ventilation openings 6 near the top to
permit air to flow for cooling the wearer's head. Here, the
ventilation openings 6 are teardrop shaped, each pointing toward
the rear 10 of the helmet 2 to give a visual sensation of speed.
For clarity sake, the various layers of the materials used in the
construction of the helmet 2 appear in the openings 6 as a single
layer 14. Ventilation openings can also be on the other side of the
helmet 2 (not shown) if the helmet has a symmetric design. Such
openings 6 are exemplary, and can have various other shapes or be
omitted altogether, depending upon the type of helmet. Also,
helmets constructed in accordance with the invention can have other
types of openings, such as ear holes.
[0036] FIG. 2 shows a cross section of the helmet 2 along the line
A-A' in FIG. 1. In the embodiment shown, the helmet 2 includes an
outer shell layer 20, a compressible middle layer 24, a hard inner
shell layer 28, and a compressible internal liner 32. The outer
shell layer 20, middle layer 24, and inner shell layer 28 together
provide an impact-absorbing shell 30 of the present invention. As
used herein, a layer is compressible based on the relative ease
with which that layer decreases in thickness in response to an
applied force. In general, compressible layers are more apt to
decrease in thickness in response to an applied force than hard
layers. The compressible layers 24, 32 can compress discernibly in
response to an applied force. In contrast, no readily discernible
compression, as defined by a readily discernible decrease in
thickness, occurs if a comparable force is applied directly to the
inner shell layer 28, although that layer may temporarily deform by
bending. Numerical hardness values, determined according to any one
of a variety of hardness tests, such as a Shore (Durometer) Test,
can be used to measure the relative hardness of each layer. In
general, compressible layers measure softer than hard layers.
[0037] As described in detail below, each of the layers can be
constructed of a lightweight material, thus contributing towards
the construction of a lightweight helmet. Although not drawn to
scale, FIG. 2 shows one example of the relative thicknesses of the
various layers and coating. These relative thicknesses can also
depart from those shown in FIG. 2 without departing from the
principles of the invention. For example, a bike helmet could be
made with a thick inner shell layer 28 (e.g., of expanded
polystyrene) and with a middle layer 24 of TPE that is thinner than
the inner shell layer 28. Also, additional layers can be disposed
between the middle layer 24 and the inner shell layer 28, or
between the internal liner 32 and the inner shell layer 28, without
departing from the principles of the invention.
[0038] The outer shell layer 20 covers the middle layer 24 and
serves various functions. For example, the outer shell layer 20 can
provide durability by protecting the helmet 2 from punctures and
scratches. Other functions include presenting a smooth surface for
deflecting tangential impacts, waterproofing, and displaying
cosmetic features such as coloring and identifying the product
brand name. In a preferred embodiment, this outer shell layer 20 is
made of a thermoplastic material.
[0039] Beneath the outer shell layer 20, the compressible middle
layer 24 covers an outer surface of the inner shell layer 28. The
middle layer 24 attaches to the inner shell layer 28. A primary
function of the middle layer 24 is impact energy absorption.
Preferably, the middle layer 24 is constructed of a thermoplastic
elastomer material.
[0040] Thermoplastic elastomers or TPEs are polymer blends or
compounds, which exhibit thermoplastic characteristics that enable
shaping into a fabricated article when heated above their melting
temperature, and which possess elastomeric properties when cooled
to their designed temperature range. Accordingly, TPEs combine the
beneficial properties of plastic and rubber, that is, TPEs are
moldable and shapeable into a desired shape when heated and are
compressible and stretchable when cooled. In contrast, neither
thermoplastics nor conventional rubber alone exhibits this
combination of properties. Further, introduction of a chemical
foaming agent during processing can change certain TPEs into foam.
This foaming serves to reduce the density and weight of the
material, and to increase its compressibility. The resulting foam
material remains a TPE.
[0041] To achieve satisfactory purposes, conventional rubbers must
be chemically crosslinked, a process often referred to as
vulcanization. This process is slow, irreversible, and results in
the individual polymer chain being linked together by covalent
bonds that remain effective at normal processing temperatures. As a
result, vulcanized rubbers do not become fluid when heated to these
normal processing temperatures (i.e., the rubber cannot be melted).
When heated well above normal processing temperatures, vulcanized
rubbers eventually decompose, resulting in the loss of
substantially all useful properties. Thus, conventional vulcanized
rubbers cannot be formed into useful objects by processes that
involve the shaping of a molten material. Such processes include
injection molding, blow molding and extrusion, and are extensively
used to produce useful articles from thermoplastics.
[0042] Thermoplastics are generally not elastic when cooled and
conventional rubbers are not moldable using manufacturing processes
and equipment currently used for working with thermoplastics, such
as injection molding and extrusion. These processes, however, are
applicable for working with TPEs.
[0043] Most TPEs have a common feature: they are phase-separated
systems. At least one phase is hard and solid at room temperature
and another phase is elastomeric and fluid. Often the phases are
chemically bonded by block or graft polymerization. In other cases,
a fine dispersion of the phases is apparently sufficient. The hard
phase gives the TPEs their strength. Without the hard phase, the
elastomer phase would be free to flow under stress, and the
polymers would be unusable. When the hard phase is melted, or
dissolved in a solvent, flow can occur and therefore the TPE can be
processed. On cooling, or upon evaporation of the solvent, the hard
phase solidifies and the TPEs regain their strength. Thus, in one
sense, the hard phase of a TPE behaves similarly to the chemical
crosslinks in conventional vulcanized rubbers, and the process by
which the hard phase does so is often called physical crosslinking.
At the same time, the elastomer phase gives elasticity and
flexibility to the TPE.
[0044] Examples of TPEs include block copolymers containing
elastomeric blocks chemically linked to hard thermoplastic blocks,
and blends of these block copolymers with other materials. Suitable
hard thermoplastic blocks include polystyrene blocks, polyurethane
blocks, and polyester blocks. Other examples of TPEs include blends
of a hard thermoplastic with a vulcanized elastomer, in which the
vulcanized elastomer is present as a dispersion of small particles.
These latter blends are known as thermoplastic vulcanizates or
dynamic vulcanizates.
[0045] TPEs can also be manufactured with a variety of hardness
values, e.g., a soft gel or a hard 90 Shore A or greater. One
characteristic of the TPE material is its ability to return to its
original shape after the force against the helmet 2 is removed
(i.e., TPE material is said to have memory). Other characteristics
of TPE include its resistance to tear, its receptiveness to
coloring, and its rebound resilience elasticity. Rebound resilience
elasticity is the ratio of regained energy in relation to the
applied energy, and is expressed as a percentage ranging from 0% to
100%. A perfect energy absorber has a percentage of 0%; a perfectly
elastic material has a percentage of 100%. In general, a material
with low rebound resilience elasticity absorbs most of the applied
energy from an impacting object and retransmits little or none of
that energy. To illustrate, a steel ball that falls upon material
with low rebound resilience elasticity experiences little or no
bounce; the material absorbs the energy of the falling ball. In
contrast, the ball bounces substantially if it falls upon material
with high rebound resilience elasticity.
[0046] Preferred embodiments of the middle layer 24 are constructed
of a TPE material with low rebound resilience elasticity (here, a
low rebound resilience elasticity corresponds to a rebound
percentage of approximately 50% or less, and preferably 25% or
less). Examples of TPEs with low rebound resilience elasticity
include Trefsin.TM., manufactured by Advanced Elastomer Systems of
Akron, Ohio, and the product TP6DAA manufactured by Kraiburg TPE
Corp of Duluth, Ga. An advantage of these TPEs is that their low
rebound characteristic exists over a wide range of temperatures.
Preferably, the TPE material of the middle layer 24 has a
glass-transition temperature of less than -20 degrees Fahrenheit.
The glass-transition temperature is the temperature below which the
material loses its soft and rubbery qualities. A TPE material with
an appropriate glass-transition temperature can be selected for the
middle layer 24 depending on the particular application of the
helmet 2 (e.g., a glass-transition temperature of 0 degrees
Fahrenheit may be sufficient for baseball helmets, whereas a
glass-transition temperature of -40 degrees Fahrenheit may be
needed for football and hockey helmets).
[0047] TPEs can also be formed into a variety of structures. In one
embodiment, the middle layer 24 is processed into individual
members, such as cylindrical columns, or other shapes such as
pyramids, spheres, or cubes, allowing for independent movement of
each member structure, and for the free flow of air around the
members during an impact. Preferably, the individual members each
have an air-filled chamber, as described in more detail below. In
another embodiment, the layer has a honeycomb structure (i.e.,
waffle-type). The interconnected hexagonal cells of a honeycombed
structure provide impact absorption and a high strength-to-weight
ratio, which permits construction of a lightweight helmet. The
interconnected cells absorb and distribute the energy of an impact
evenly throughout the structure. The honeycomb structure also
reduces material costs because much of the material volume is made
of open cells. This structure can be any one in which the material
is formed into interconnected walls and open cells. The cells can
have a shape other than hexagonal, for example, square,
rectangular, triangular, and circular, without departing from the
principles of the invention.
[0048] The formation of the middle layer 24 on the inner shell
layer 28 can be accomplished using an extrusion, blow molding,
casting, or injection molding process. The compressible middle
layer 24 and inner shell layer 28 can be manufactured separately
and adhered together after production, or they may be manufactured
as one component, with the two layers being adhered to each other
during manufacturing. TPEs bond readily to various types of
substrates, such as plastic, and, thus, TPEs and substrates are
commonly manufactured together. With respect to solid and foam
forms of TPE structures, the softness (or conversely, the hardness)
of the middle layer 24 can also be determined over a range of
durometers. Preferably, the hardness range for these forms is
between 5 and 90 on the Shore A scale, inclusive. The thickness of
the middle layer 24 can be varied without departing from the
principles of the invention. In one embodiment, the middle layer 24
is approximately 1/4 to one inch thick.
[0049] The inner shell layer 28 is constructed of a hardened
material, such as a rigid thermoplastic, a thermoplastic alloy,
expanded polystyrene, or a fiber-reinforced material such as
fiberglass, TWINTEX.RTM., KEVLAR.RTM., or BP Curv.TM.. The inner
shell layer 28 operates to provide structure to the helmet 2,
penetration resistance, and impact energy distribution to the
internal liner 32. In one embodiment, the thickness of the inner
shell layer 28 is 1/16.sup.th of an inch. The thickness of the
inner shell layer 28 can be varied without departing from the
principles of the invention.
[0050] Providing another impact energy-absorbing layer, the
internal liner 32 contacts the wearer's head. Other functions of
the internal liner 32 may include sizing, resilience, airflow, and
comfort. In general, the internal liner 32 is constructed of a
thermoplastic elastomer, a foam material of, for example,
approximately 1/2 to 1 inch thickness, or it may be constructed of
expanded polystyrene. The compressible internal liner 32 is
attached to an inner surface of the inner shell layer 28. The
method of attachment depends upon the type of materials used (of
the inner shell layer 28 and of the internal liner 32).
[0051] Embodiments of the internal liner 32 include one or more of
the following, either alone or in combination: thermoplastic
elastomer (TPE), expanded polystyrene, expanded polypropylene,
vinyl nitrile, silicone gel, silicone foam, viscoelastic or memory
foam, and polyurethane foam. The thickness and type of foam
material can be varied without departing from the principles of the
invention.
[0052] Important to the use of the helmet of the invention is for
the helmet to fit properly and to remain in place during the
impact. In an embodiment not shown, the helmet extends downwards
from the regions near the ears and covers the angle of the wearer's
jaw. This extension may be flexible, and when used in conjunction
with a chinstrap, may be drawn in tightly to provide a snug fit
around the jaw. FIG. 3 shows another embodiment of a helmet 2'
constructed in accordance with the invention. Here, the helmet 2'
is a football helmet (facemask and chinstrap not shown). This
helmet 2' illustrates a design that covers the ears and a portion
of the wearer's jaw. The helmet 2' has ventilation openings 6' near
the top and on the sides of the helmet 2' and an ear hole 8. Again,
for clarity sake, the various layers of materials used in the
construction of the helmet 2' appear in each opening 6' as a single
layer 14'.
[0053] FIG. 4 shows a cross-section of an embodiment of a layered
shell 30' for use, for example, in the construction of protective
headgear. The shell 30' has an outer layer 20', an inner layer 28',
and a plurality of independent compressible members 50 disposed
between the inner and outer layers 28', 20'. Each member 50
attaches to an internally facing surface of the outer layer 20' and
to a surface of the inner layer 28' that faces the outer layer 20'.
Members 50 are independent in that each individual member 50 can
compress or shear independently of the other members 50. Here,
members 50 have a resilient, compressible solid or foam
construction.
[0054] Members 50 can range from approximately one-eighth inch to
one inch in height and one-eighth inch to one-half inch in
diameter, and need not be of uniform height or diameter. Although
shown to have the shape of columns, the members 50 can have a
variety of shapes, for example, pyramidal, cubic, rectangular,
spherical, disc-shaped, and blob-shaped. Preferably, the members 50
are constructed of TPE material (e.g., solid form, foam), although
other types of compressible materials can be used for producing the
members 50, without departing from the principles of the invention,
provided such materials can make the members sufficiently resilient
to respond to various types of impact by leaning, stretching,
shearing, and compressing.
[0055] In one embodiment, there is a spatial separation between
each member 50. Referred to herein as an interstitial region 52,
the spacing between the members 50 bounded between the inner and
outer layers 28', 20' defines a volume of fluid. As used herein,
this fluid is any substance that flows, such as gas and liquid. The
distance between adjacent members 50 can be designed so that a
desired proportion of the volume of the shell 30' (e.g., >50%)
is comprised of fluid. In a preferred embodiment, the fluid within
the interstitial region 52 is air. An air-containing interstitial
region 52 provides for lightweight headgear.
[0056] In FIG. 4, the distance between the outer layer 20' and the
inner layer 28' is exaggerated in order to reveal the members 50 of
the middle layer 24'. (The middle layer 24' here comprises the
members 50 and interstitial region 52). In general, the outer layer
20' and inner layer 28' approach and may touch each other so that
any gap between the layers 20', 28' either is imperceptible or does
not exist. Preferably, the outer and inner layers are not directly
attached to each other at any point along the shell 30'. Not
directly attaching the layers enables the outer layer to move
during impact independently of the inner layer in a scalp-like
fashion. At one or more points along the edge of the shell where
the outer layer approaches the inner layer, an elastic adhesive or
another intervening substance or material, can be applied in
between the two layers in order to make the layers 20', 28' closely
approximate other. This adhesive can be an elastomeric gel (similar
to rubber cement) or an adhesive strip that attaches to each layer
20', 28'. Despite this adhesive attachment of the intervening
material to each layer 20', 28', the outer layer can still move
relative to the inner layer in scalp-like fashion. Gaps may be
present in this adhesive at various locations along the edge of the
shell to permit air to escape from the middle layer 24' during an
impact to the shell or to enter the middle layer 24' when the
impact is over, as described in more detail below.
[0057] FIG. 5 shows an embodiment of a simplified manufacturing
schematic for producing the shell 30' for use in constructing
protective headgear. In this example, the compressible members 50
are constructed of TPE material 54. In step 60, a TPE foam 58 is
produced from the TPE material 54, as described above. At step 64,
the TPE foam 58 is extruded into a desired structure 61, here, for
example, columnar members. Initial construction of the compressible
members may be in the form of a chain (i.e., a single continuous
string of multiple members, analogous to coupling between cars of a
train). Alternatively, the compressible members may be formed
together as a larger unit, which has an appearance analogous to
that of a rake when the TPE structure 61 is laid flat and which
takes a hemispherical shape when laid onto the inner layer 28'.
Other techniques for forming the members together can be practiced
to produce the desired structure 61.
[0058] The TPE foam structure 61 is placed (step 68) between and
attached to a first sheet 62 of material, to serve as the inner
layer 28', and a second sheet 63 of material to serve as the outer
layer 20'. The compressible members may be attached to the inner
layer 28' one member 50 at a time, for example, by adhesive.
Alternately, each member 50 can have a point, nozzle, stem, which
can be inserted into an appropriately shaped opening in the inner
layer 28' to hold that member in place. In one embodiment, the TPE
foam structure 61 has a common chemical component as the sheets 62,
63 for the inner and outer layers, thus enabling chemical adhesion
between the TPE foam structure and each layer during the
manufacturing process. Thus, secondary adhesives are unnecessary,
although not precluded from being used, to attach the TPE foam
structure to these layers. The resulting sheet of composite
structure 65 can then be cut (step 72) and formed (step 76) into
the desired shape of the shell 30' (only a portion of the shell
being shown).
[0059] Instead of cutting and shaping the inner, middle, and outer
layers together, as described above, the manufacture and shaping of
each of the three layers of the shell can occur independently, and
then the independently formed layers can be adhered to one another.
As another embodiment, the middle and inner layers can be shaped
together and the outer layer independently; then, the outer layer
can be adhered to the middle layer. This embodiment can lead to the
modularization of the manufacture of helmets. For instance, the
interior components of a helmet, i.e., the liner, inner layer, and
middle layer, can have standardized construction (i.e., the same
appearance irrespective of the type of sports helmet for which the
interior components are to be used), with the outer sport-specific
layer, which is adhered to the middle layer, or injection molded
around the interior components, providing the customization of the
helmet for a particular sport.
[0060] As shown in FIG. 6, a compressible (e.g., foam) internal
liner 32' can then be added (step 80) to the multilayer shell 30'.
FIG. 6 shows a cross-section of a portion of the shell 30' and of
the internal liner 32'. The internal liner 32' is attached (e.g.,
with an adhesive) to an internally facing surface of the inner
layer 28'. The shape of the internal liner 32' conforms to the
general shape of the shell 30' and to the shape of a wearer's
head.
[0061] The shell 30' of the invention may reduce both linear
acceleration and rotational acceleration experienced by the head of
the headgear wearer. Linear acceleration occurs when the center of
gravity of the wearer's head becomes rapidly displaced in a linear
direction, such as might occur when the headgear is struck from the
side. Rotational acceleration, widely believed to be a primary
cause of concussion, can occur when the head rotates rapidly around
the center of gravity, such as might occur when the headgear is
struck tangentially. Most impacts impart both types of
accelerations.
[0062] FIG. 7A illustrates an exemplary simulated operation of the
shell 30', with solid or foam members 50, undergoing a direct
impact from an object 100. In this example, the shell 30' operates
to reduce linear acceleration of the headgear wearer's head 104.
When the object 100 strikes the outer layer 20', the members 50
directly beneath the outer layer 20' at the point of impact
compress. The compression of the shell 30' also causes air to exit
the middle layer 24' (arrow 108) through one or more openings at an
edge of the shell 30' where the inner and outer layers 28', 20'
approach each other. Air also moves through the interstitial region
away from the point of impact (arrow 110). The combined effects of
energy-absorption by the compressible members 50 and air cushioning
by the release and movement of air operate to reduce the amount of
energy that reaches the wearer's head 104. When the force of the
impact subsides, the shape and resilience of the inner and outer
layers 28', 20', operate to restore the shell 30' and the
compressed members 50 to their original shape. When returning to
the original shape, the shell 30' in effect inhales air through
each opening at the edge.
[0063] FIG. 7B illustrates an exemplary simulated operation of the
shell 30', with solid or foam members 50, undergoing a tangential
impact from an object 100. In this example, the shell 30' operates
to reduce rotational acceleration of the wearer's head 104. When
struck by an object tangentially, the outer layer 20' shears with
respect to the inner layer 28' in a direction of motion of the
object, as illustrated by arrows 112. The smoothness of the outer
layer 20' can operate to reduce friction with the object 100 and,
correspondingly, to reduce the rotational force experienced by the
shell 30'. Members 50 at the point of impact compress to some
extent and shear with the outer layer 20'. As with the example of
FIG. 7A, the compression causes air to exit the middle layer 24'
and to move within the interstitial region. The combined effects of
the shearing motion of the outer layer 20' and members 50, of the
energy-absorbing compression of the middle layer 24', and of the
release and movement of air operate to reduce the rotational force
reaching the wearer's head 104. The shell 30' and members 50 return
to their original shape after the force of the impact subsides.
[0064] FIG. 8A shows an embodiment of a compressible member 50' for
use in constructing the middle layer 24' for the shell 30' in
accordance with the invention. Embodiments of the invention can use
this type of member 50' in conjunction with or instead of openings
at the edge of the shell 30'. Making the member 50' of TPE material
further operates to improve the energy-absorbing effect of the
shell, although other types of compressible materials can be used
for producing the member 50'. The member 50' has a top surface 120,
a bottom surface 124, and a sidewall 128 that define a hollow
internal chamber 132. The top surface 120 attaches to the outer
layer 20' of the shell 74, and the bottom surface 124 attaches to
the inner layer 28'. The bottom surface 124 has a small opening 136
formed therein. When the member 50' compresses in the general
direction indicated by arrow 140, airflow 144, for example, exits
the small opening 136.
[0065] The size of the opening 136 is designed to produce a
rate-sensitive response to any impact causing compression of the
member 50'. For instance, if the application of force upon the
member 50' is gradual or of relatively low energy, the opening 136
permits sufficient air to pass through so that the member 50'
compresses gradually and presents little resistance against the
force. For example, an individual may be able to compress the shell
of the protective headgear manually with a moderate touch of a hand
or finger, because the energy-absorbing middle layer and, in some
embodiments, the outer and inner layers are made of compressible
materials. Because the application of the force is gradual, the
wearer's head is not likely to accelerate significantly and thus is
less likely to experience concussion. In addition, the wearer may
feel the air being expelled from the members 50' onto his or her
head, as described further below.
[0066] If, as illustrated by FIG. 8B, the application of force upon
the member 50' occurs instantaneously or is of relatively high
energy, the energy of impact is converted to heat, and laminar or
turbulent air flows within the chamber 132. The size of the opening
136, which is small relative to the volume of air moved by the
force, restricts the emission of the turbulent or laminar air from
the chamber 132 and thus causes resistance within the chamber 132.
Eventually the resistance is overcome and air flows out, but during
this process, the impact energy is thus converted to heat. This
conversion of impact energy to heat occurs in some proportion to
the amount of energy delivered, also termed a rate-sensitive or a
non-linear response, and reduces the energy delivered to the head.
An advantage of this structure is that when the member 50'
compresses and empties the entire volume of air, a length of TPE
material remains, which further absorbs energy. This helps prevent
"bottoming out", i.e., fully compressing so that the cushioning
effect of the member 50' is lost and the impinging force transfers
directly to the wearer's head. In addition to providing this
rate-sensitive response, the member 50' can also stretch and bend
during tangential impact similarly to the members 50 described
above, as illustrated by FIG. 8C and FIG. 8D.
[0067] FIG. 8E shows the embodiment of the compressible member 50'
after becoming compressed. Because of its resilient nature, the
tendency of the member 50' is to return to its uncompressed shape.
The inner and outer layers 28', 20' to which the member 50' is
attached also contribute to the restoration of the member 50' to
its uncompressed shape. The tendencies of the inner and outer
layers 28', 20' to return to their pre-impact shape, because of
their semi-rigidness and resiliency, operate to pull the member 50'
back to its uncompressed shape. Accordingly, after the force is
removed from the shell 30', the member 50' expands in the direction
indicated by arrow 150, consequently drawing air in through the
opening 136 as indicated by arrows 144'. FIG. 8F illustrates a
simulated sequence of expansion of a rate-sensitive compressible
member 50', as the force is removed.
[0068] FIG. 9A shows a cross-section of another embodiment of a
rate-sensitive compressible member 50'' that is generally
rectangular in shape (i.e., a strip). The member 50'' has a top
surface 160, a bottom surface 164, sidewalls 168-1, 168-2
(generally, 168), and a hollow internal chamber 172. The top
surface 160 attaches to the internally facing surface of the outer
layer 20' of the shell 30'', and the bottom surface 164 attaches to
a surface of the inner layer 28'. Each sidewall 168 has a
respective small opening 176-1, 176-2 (generally, 176) formed
therein. (Practice of the invention can be achieved with only one
of the sidewalls 168 having an opening). When the member 50''
compresses generally in the direction indicated by arrow 180,
airflows 184 exit the small openings 176 and pass through the
interstitial region of the shell. This embodiment illustrates that
a variety of shapes, for example, disc-shaped, cylindrical, and
pyramidal, can be used to implement rate-sensitive compressible
members of the invention, capable of converting impact energy to
heat of turbulent or of laminar airflow.
[0069] FIG. 9B shows a cross-section of a shell 30''' having a
plurality of rate-sensitive compressible members 50''' disposed
between the outer layer 20' and inner layer 28'. Each compressible
member 50''' has a plurality of openings 176 for the passage of
fluid (i.e., air). The inner layer can have an openings 200 formed
therein, to permit the passage of fluid. Fluid escaping the
rate-sensitive compressible members 50''' during impact, or
returning to the compressible members 50''' after impact, thus have
avenues for leaving and entering the shell 30'''. Embodiments of
the invention can have one or more of such openings 200 in addition
to or instead of openings at the edge of the shell. Further, other
embodiments can use such openings 200 with other types of
compressible members (e.g., those described in FIG. 4).
[0070] FIG. 10A shows a cross-section of an embodiment of a shell
230 having an outer layer 220, an inner layer 228, and a plurality
of the rate-sensitive compressible members 50' (FIG. 8A) disposed
therebetween. The opening 136 of each rate-sensitive compressible
member 50' aligns with an opening (not shown) in the surface of the
inner layer 228 and through any liner 232 so that expelled or
inhaled air (arrows 210) can pass into the interior of the
protective headgear. Similarly, such openings 136 can be on the
sides of the compressible member 50', allowing the release and
return of air through the interstitial region of the shell 230.
FIG. 10B shows the shell 230, with rate-sensitive compressible
members 50' and an internal liner 232, on the head 234 of a
user.
[0071] FIG. 10C illustrates an exemplary simulated operation of the
shell 230, with rate-sensitive members 50', undergoing a direct
impact from an object 236. In this example, the shell 230 operates
to reduce linear acceleration of the headgear wearer's head 234.
When the object 236 strikes the outer layer, the members 50'
directly beneath the outer layer at the point of impact compress.
The compression of the shell 230 also causes air to exit the
members 50' (arrows 238) and enter the interior of the headgear
through the openings in the members 50' and in the inner layer.
[0072] FIG. 10D illustrates an exemplary simulated operation of the
shell 230, with rate-sensitive compressible members 50', undergoing
a tangential impact from an object 236. In this example, the shell
230 operates to reduce rotational acceleration of the wearer's head
234. When struck by an object tangentially, the outer layer shears
with respect to the inner layer in a direction of motion of the
object, as illustrated by arrows 240. Members 50' at the point of
impact compress to some extent and shear with the outer layer. As
with the example of FIG. 10C, the compression causes air to exit
the members 50' and to enter the interior of the headgear. The
combined effects of the shearing motion of the outer layer and
members 50', of the rate-sensitive and energy-absorbing compression
of the members 50', and of the release of air into the interior of
the headgear operate to reduce the rotational force reaching the
wearer's head 104.
[0073] As an illustration of an exemplary use of the invention,
FIG. 11A shows a rear view of an embodiment of protective headgear
250 embodying the invention. The headgear 250 includes a pattern
254 of strip-shaped members 50'' (FIG. 9A) disposed between outer
and inner layers of the shell. FIG. 11B shows a side view of the
headgear 250 with another pattern 258 of strip-shaped members 50''.
A variety of other patterns is possible without departing from the
principles of the invention.
[0074] While the invention has been shown and described with
reference to specific preferred embodiments, it should be
understood by those skilled in the art that various changes in form
and detail may be made therein without departing from the spirit
and scope of the invention as defined by the following claims. For
example, more than one type of compressible member can be combined
to construct a shell for a protective headgear.
* * * * *