Note: Descriptions are shown in the official language in which they were submitted.
CA 02752516 2015-10-01
DEFORMABLE SAFETY HELMET
Background of the invention
The invention relates to a safety helmet delineating a cavity open onto the
outside through an opening to engage the head in the cavity, comprising an
external shell in a single part, a plurality of damping elements added-on to
the
inside of the shell, and joining means to join the damping elements to one
another.
State of the art
A safety helmet of this type is known from the document US6665884B1 which
provides a rigid shell only deforming under the effect of an external impact.
Lateral, front and top damping elements are added inside the shell. Each of
the
lateral elements is subdivided into a lateral part fixed to the shell and a
rear part
articulated freely on the lateral part. Each lateral damping element is
therefore
partially fixed to the shell. The free ends of the rear parts are joined to
one
another by a flexible band. The rear parts and the flexible band are situated
at a
distance from the internal surface of the shell. This results in the presence
of
dead volumes located between the .shell and the damping elements, which does
not make for optimal protection. The front damping element is completely
dissociated from the lateral damping elements, with interposition of empty
spaces
at the level of which no tightening is applied to the head in position in the
cavity of
the shell. Tightening on the head is only performed laterally and from the
rear,
which means that the hold of the helmet on the head and the protection
afforded
are debatable. Finally, the tightening function is performed by the rear
flexible
band and by the compressibility of the lateral damping elements. The shell
situated at a distance from these parts with interposition of dead volumes as
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indicated above does not participate in tightening on the head and does not
present any possible adjustment to the morphology of the user's head. Only the
lateral elements adjust to the morphology of the head.
Furthermore, shocks on a helmet when falling are seldom purely perpendicular
to
the shell and it frequently happens that a component tangential to the shell
causes a
violent torsional torque on the head and then on the neck. These sudden
rotations
of the head cause internal injuries to the elements joining the brain to the
top.
Helmets of the prior art do not provide protection against this phenomenon,
and
they are not completely satisfactory as far as the safety question is
concerned.
Object of the invention
The object of the invention consists in providing a safety helmet whereby the
comfort, strength, aesthetics and safety are optimized whatever the morphology
of
the user's head.
According to the present invention, there is provided a safety helmet
comprising:
a cavity open onto an outside through an opening to engage a head of a user in
the cavity;
an outer shell in a single part, and made from elastically deformable
material,
having a modulus of elasticity between 1500 and 4500 MPa;
a plurality of damping elements added-on to an inside of the shell, wherein
the
damping elements are formed by a rigid foam, and the damping elements are
arranged at the periphery of the opening against an inner surface of the shell
to
form an inner supporting belt completely in contact with the shell; and
joining means to join the damping elements to one another, to allow relative
movements between the damping elements,
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wherein a position of the head of the user in the cavity causes a deformation
of the supporting belt by elastic deformation of the shell according to the
morphology of the head of the user, generating permanent tightening of the
supporting belt against the head of the user in a uniform manner along the
supporting belt,
wherein the joining means comprises a single structure connecting the
damping elements to one another,
wherein the single structure is in the form of a spider, the head of which is
fixed to a top damping element and each leg of which performs joining between
the
top damping element and a peripheral damping element, and
wherein the top and peripheral damping elements are obtained by
overmolding on the single structure.
Preferably, this object is achieved by a helmet, in particular by the fact
that the
damping elements are formed by a material forming a rigid foam, that the shell
is
made from elastically deformable material, and that the whole of the surface,
facing
the shell, of the damping elements arranged along the periphery of the opening
is
positioned against the inner surface of the shell so as to form an inner
supporting
belt completely in contact with the shell, the helmet being arranged in such a
way
that a position of the head in the cavity causes a deformation of the
supporting belt
by elastic deformation of the shell according to the morphology of the head,
generating permanent tightening of the supporting belt in substantially
uniform
manner against the head along the supporting belt.
¨
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The damping elements located at the periphery of the opening are for example
positioned side by side so to form a supporting belt bordering the whole of
the
periphery of the opening in order to avoid any empty spaces along the
periphery
of the opening. As the whole of the surface of the damping elements at the
periphery of the opening facing the shell is positioned against the shell,
this
results in the absence of dead volumes located between the shell and the
damping elements, thereby providing optimal protection. The shell is designed
to
deform elastically in flection when the head is in position in the cavity of
the
helmet to generate tightening of the supporting belt against the head, by
elastic
return of the shell to its natural configuration before the head was placed in
the
cavity. The shell therefore automatically adjusts to the morphology of the
users
head. All of the damping elements bordering the periphery of the opening
participate in tightening and adjust to the morphology of the head. A
supporting
belt formed in this way and arranged so as to deform when the head is in
position
in the cavity of the helmet, by deformation of the shell against which it is
completely pressing, has the effect of clamping the head in permanent and
uniform manner over the circumference of the belt, which makes for an improved
hold of the helmet on the head and enhanced protection.
Brief description of the drawings
Other advantages and features will become more clearly apparent from the
following description of particular embodiments of the invention given for non-
restrictive example purposes only and represented in the appended drawings, in
which:
- figure 1 is a perspective bottom view of a helmet according to the
invention,
- figure 2 is a longitudinal cross-section of the helmet of figure 1,
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- figures 3 to 6 illustrate different alternative embodiments of
joining means
between the damping elements,
- figures 7 to 10 represent different alternative embodiments of the shape of
the damping elements,
- figure 11 is a cross-section of a helmet comprising separating elements.
Description of preferred embodiments of the invention
Safety helmet 10 of figures 1 and 2 delineates a cavity open onto the outside
through an opening 11 to engage the head inside the cavity. Helmet 10
comprises an outer shell 12 in a single part and devoid of notches. A
plurality of
damping elements 13 are added inside shell 12 so as to form a damping liner
substantially covering the whole of the inner surface of shell 12. Joining
means
can be provided to join damping elements 13 to one another, but such joining
means are not indispensable. It is possible to provide for each damping
element
13 to be attached to the shell without being connected with the other damping
elements 13.
What should be understood by "notch" is a local elongate removal of material
over the whole thickness of the helmet (i.e. over the whole thickness of the
foam
liner and over the whole thickness of the shell) arranged in such a way as to
open
out onto the edges of the helmet. Shell 12 can however comprise local
ventilation
openings having a closed outline, i.e. not opening out onto the edges of the
helmet.
Damping elements 13 are made from expanded polystyrene (PSE) or any other
substantially rigid foam which presents an economic interest comparable to
that
of PSE or interesting damping properties. Shell 12 is for its part made from
elastically deformable material such as a thermoplastic polymer material, such
as
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polycarbonate, acrylonitrile butadiene styrene (or ABS), polystyrene,
polyethylene
terephtalate glycol (or PETG), or polyvinyl chloride (or PVC). The choice of
the
material of shell 12 is such that shell 12 presents a satisfactory resistance
to
external impacts and that the bending modulus of the material is comprised
5 between 1500 and 4500 MPa. For a required flexible deformability in
flection, the
thickness of outer shell 12 is for example comprised between 0.5 and 3 mm,
according in particular to the modulus of elasticity. The material forming
shell 12
also presents a tensile breaking elongation characteristic which is preferably
greater than 10%.
When they are used, the joining means between damping elements 13 can be
achieved in any manner, and are for example designed to allow relative
movements between damping elements 13.
A first solution consists in using a single structure 14 connecting all of
damping
elements 13 to one another. In the case where the damping liner is formed by a
top damping element around which a plurality of lateral, front and rear
damping
elements are angularly arranged, single structure 14 can for example be in the
form of a spider the head of which is fixed to the top damping element and
each
leg of which performs joining between the top damping element and a peripheral
damping element. In figure 3, the top, lateral, front and rear damping
elements
are achieved by overmoulding on single structure 14. In figure 5 on the other
hand, single structure 14 is not overmoulded, but is imprisoned between
damping
elements 13 and the inner surface of outer shell 12.
Another solution consists in using a plurality of discrete connecting parts
individually performing local joining between two damping elements 13. In the
case where the damping liner is formed by a top damping element around which
a plurality of lateral, front and rear damping elements are angularly
arranged,
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each connecting part performs connection between the top damping element and
a peripheral damping element. In figure 4, each connecting part is in the form
of a
loop 15 formed by closing a band made from textile or from self-grip material
of
Velcro type. One end of loop 15 passes through a passage opening arranged in
the top damping element, and the opposite end passes through a passage
opening of the peripheral damping element joined thereto. In figure 6 on the
other
hand, each connecting part is formed by an insert 16 between two axially
offset
parts. Each part is designed to collaborate either with the top damping
element or
with a peripheral damping element, and comprises for this purpose of plurality
of
anti-return tabs in the form of a fir-tree.
The whole surface of damping elements 13 arranged along the periphery of the
opening 11 facing towards shell 12 is positioned against the inner surface of
shell
12 so as to form a supporting belt bordering the periphery of the opening and
completely in contact with the shell. The whole of the surface facing shell 12
of
each damping element 13 forming the supporting belt is therefore completely in
contact with the inner surface of shell 12 when the user's head is in position
in
the cavity of the helmet. In order to form a supporting belt bordering the
whole of
the periphery of opening 11 so as to avoid empty spaces along the periphery of
opening 11, damping elements 13 arranged at the periphery of opening 11 can
be positioned side-by-side or placed at a negligible distance of a few
millimeters.
The supporting belt is in the shape of a ring internally delineating the
outline of
opening 11. Externally, the supporting belt is completely in contact with the
inner
surface of shell 12, guaranteeing the absence of dead volumes located between
shell 12 and damping elements 13 constituting the belts so as to provide
optimum
protection.
The shape, size and thickness of shell 12, and the thickness of damping
elements 13 constituting the supporting belt, are chosen such that the inner
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dimensions of the supporting belt (delineating the periphery of opening 11)
are
perfectly adjusted to the required perimeter of the head in the contact zone
scheduled for the head. The helmet is hereby arranged in such a way that
positioning of the head in the cavity of the helmet causes deformation of the
supporting belt resulting in an elastic flectional deformation of the shell
generating
permanent tightening of the supporting belt against the head in substantially
uniform manner along the supporting belt by flexible biasing of the shell to
return
to its natural configuration (before the head was positioned in the cavity of
the
helmet).
Whatever the joining means between damping elements 13, securing of the
damping liner to the inner surface of shell 12 can be performed by fixing at
least
one damping element 13 of the liner to the shell. Such fixing means can be
designed to allow a slight sliding between shell 12 and fixed damping elements
13. This slight sliding between damping elements 13 and shell 12, and the
movements between damping elements 13, can generate potentially unpleasant
noises against which it is possible to act by covering the inner surface of
the shell
and/or the damping elements with a coating of light felt, spray, or silicone
type, or
such like.
In the case where the damping liner is formed by a top damping element around
which a plurality of lateral, front and rear damping elements are angularly
arranged, a first solution consists in using fixing means performing securing
of
the top damping element with the inner surface of shell 12. In a second
solution,
helmet 10 comprises means for integrally fixing the damping elements
constituting the supporting belt to shell 12 so that the supporting belt is
completely secured to the inner surface of shell 12. It should then preferably
be
provided for the means for integrally fixing the damping elements constituting
the
supporting belt to shell 12 to allow a slight amount of sliding between shell
12 and
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the fixed damping elements. This characteristic can be obtained by using
securing means of Velcro self-grip band type or of cooperating loop/hook
type,
and presents the advantage of better adjustment of the damping elements to the
morphology of the head.
In an alternative embodiment improving the comfort at the level of the contact
between the supporting belt and the head, compressible elements 17 can be
arranged on the surface opposite the surface of the damping elements
constituting the supporting belt fixed to shell 12. Such compressible elements
17
to can cover the whole or a part of the circumference of the supporting
belt, and are
made from strong flexible foam, for example from vinyl ethylene acetate,
either
added-on or provided when the damping elements of the supporting belt are
manufactured. Such compressible elements 17 have the function of creating a
complementary belt enabling a head having a larger circumference to be
positioned inside a helmet provided for a given head circumference, by
deformation of compressible elements 17.
Furthermore, filling elements can be arranged to fill the gaps between damping
elements 13 over the whole or a part of the damping liner. Such filling
elements
can be made from any suitable strong flexible material, for example from vinyl
ethylene acetate.
According to an embodiment that is in no way restrictive, the filling elements
arranged between damping elements 13 can be formed by separating elements
18. As illustrated in figure 11, such separating elements 18 can be formed by
flexible connectors adopting a general V-shape the purpose of which is to
permanently maintain a minimum space at rest between each of damping
elements 13. By deformation of the flexible connectors due to the effect of
external forces, this minimum space can temporarily decrease and then return
to
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its natural size by flexible return of the connectors to their natural rest
configuration when the external forces cease. This embodiment is particularly
advantageous in the case of absence of compressible elements 17.
In addition to creating sliding between shell 12 and damping elements 13,
separating elements 18 present a first advantage of guaranteeing that a
placing
effect of damping elements 13 against the inner surface of shell 12 is
constantly
maintained, eliminating any mobility of elements 13, in particular so long as
the
helmet is not used. They further facilitate deformations of the assembly
formed by
the shell and by the segmented liner by fostering sliding. Finally, they
enable
noises and gratings caused by contact between elements 13 and between the
elements and shell 12 to be eliminated. Separating elements 18 can be obtained
by thermoforming or by injection of material (for example PE or PP).
Helmet 10 can further comprise a chinstrap connected at its ends to two
opposite
damping elements each belonging to the supporting belt.
The purpose of figures 7 to 10 is to illustrate the different shape variants
that
damping elements 13 of the damping liner are able to take. In figure 10, a top
damping element is connected to a plurality of lateral, front and rear damping
elements arranged at the periphery of the top damping element. Figure 9 is a
variant of figure 10 wherein the peripheral damping elements are subdivided
into
two independent elements offset in the direction of the bottom of the cavity.
Figures 7 and 8 on the other hand represent a liner where damping elements 13
are hexagonal and distributed uniformly over the whole inner surface of shell
12,
with a respectively large and smaller distribution density.
All of the alternative embodiments of the helmet describing in the foregoing
present the advantage of a great quality of ventilation inside the helmet. The
heat
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originating from the user's head is in fact mainly radiation on the
circumference of
the skull. The slits or gaps between elements 13 create an air flow network
enabling efficient removal of heat and moisture. This effect can be enhanced
if
shell 12 is provided with holes opening out on the outside and facilitating
creation
5 of a variable ventilation draught according to the mobility of the user.
Finally, as far as safety is concerned, the embodiments described in the
foregoing where lateral damping elements 13 are floating enable a part of the
energy to be absorbed by sliding and pivoting between the head and the shell
in
10 the case of tangential force components. This movement of a few tens of
millimeters is capital to enable the stress peak to be absorbed and to remain
below the threshold of damage to the brain. In the case of a greater stress
force,
sliding in the plane of the supporting belt between the head and helmet is
possible to dampen the shock wave. This possibility is allowed due to the free
deformation of the perimeter of the supporting belt.
In an advantageous alternative embodiment, the means for fixing top damper
element 13 and shell 12 can act as a fuse element and enable the two elements
to be at least partially disunited from one another, enabling a larger
rotation of the
shell with respect to the liner, making transmission of forces almost nil.
Such a
fixing means can be achieved with glue, for example of hot melt glue type, or
a
magnet or with a self-grip material of Velcro type. Shell 12 cannot disunite
as
the chinstrap or equivalent under the user's chin guarantees the unity of the
whole.
