AU2020286992B2 - Helmet - Google Patents

Abstract

A helmet (100) including an impact absorbing layer (102), an outer shell (104) and a connector (106, 114). The outer shell is mounted on the outer surface of the impact absorbing layer. The connector connects the outer shell to the impact absorbing layer, to retain the outer shell on the impact absorbing layer. The connector is also arranged to allow the outer shell to separate from the impact absorbing layer when the helmet is subject to an impact.

Description

PCT/GB2020/051378

- 1

Helmet

This invention relates to a helmet, in particular a helmet having a detachable outer

shell.

Head injuries, which can be incurred as a result of participation in sports such as

cycling, horse riding or rock climbing, are a common cause of serious brain injuries.

Impact protection is therefore important in preventing brain injuries as a result of

impacts to the head. Head protection, in the form of helmets, is designed to reduce

the forces experienced by a user's head during an impact. Typically, a helmet

comprises at least one impact absorbing layer which is designed to absorb a

portion of the forces to which the helmet is subjected during an impact.

However, a helmet often does not provide adequate protection during an oblique

impact which subjects the helmet to significant tangential forces. Oblique impacts

are common, as it is rare for an impact to occur directly along the normal to the

outer surface of the helmet with no additional components in other directions.

Tangential forces result in the rotational acceleration of the brain, which has been

linked to bridging vein rupture. In turn, this may be responsible for subdural

haematomas, and diffuse axonal injuries.

It is an aim of the present invention to provide an improved helmet.

When viewed from a first aspect the present invention provides a helmet

comprising:

an impact absorbing layer;

an outer shell mounted on the outer surface of the impact absorbing layer;

and and a connector which connects the outer shell to the impact absorbing layer to

retain the outer shell on the impact absorbing layer;

wherein the connector is arranged to allow the outer shell to separate from

the impact absorbing layer when the helmet is subject to an impact.

This invention relates to a helmet including an impact absorbing layer and an outer

shell, which are connected together by a connector, e.g. to retain the outer shell on

the impact absorbing layer during normal use. When the helmet is subject to an

impact (and thus an external force acts on the helmet) the connector is arranged

such that it allows the outer shell to separate from the impact absorbing layer (i.e.

be moved to a different position from that in which the outer shell is mounted on the

impact absorbing layer and the connector is connecting them). For example, the

outer shell may be configured such that it is able to rotate about the impact

absorbing layer when not connected to the impact absorbing layer by the

connector.

The skilled person will appreciate that owing the way in which the outer shell is

detachably connected to the impact absorbing layer via the connector, the outer

shell is able to move, and for example rotate, about the outer surface of the impact

absorbing layer when the outer shell has separated from the impact absorbing layer

(owing to no longer being held in place by the connector). Therefore, when the

helmet is subject to an impact that involves at least a tangential component (i.e. that

is not solely along the normal direction to the outer surface of the helmet), at least a

portion of the tangential forces produced by the impact may act to rotate the outer

shell. This helps to reduce the rotation of the head of the user and thus the transfer

of tangential forces from the impact. This is because the user's head (e.g. with the

impact absorbing layer still attached thereto) may able to translate (e.g. slide or

rotate) within the outer shell instead of being subject to the tangential forces itself.

When the tangential forces experienced by the head are reduced (thus reducing the

rotational acceleration experienced by the head), the risk of injuries such as

bridging vein rupture are decreased. Reducing the tangential forces experienced by

a user's head further reduces the risk of neck injuries caused by over-rotation of the

head with respect to the neck.

In at least preferred embodiments, the impact absorbing layer is designed to

provide a user's head with a degree of protection against bulk forces exerted in an

impact. Thus preferably, the impact absorbing layer is arranged to absorb at least a

portion of the normal component of the forces exerted on the helmet during an

impact.

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The impact absorbing layer may be formed from any suitable and desired material,

such as expanded polystyrene. In a preferred set of embodiments, the impact

absorbing layer comprises a hollow cell structure, e.g. comprising a plurality of

hexagonal cells (in cross section). Preferably, at least a plurality of the cells

tessellate with each other. For example, the impact absorbing layer structure may

comprise a micro-truss lattice or an out-of-plane honeycomb. The impact absorbing

layer may further comprise a rim, e.g. around the edge (below) the hollow cell

structure.

Typically, in conventional helmets comprising an outer shell, the outer shell may be

provided predominately as an aesthetic feature used to improve the appearance of

the helmet. Such outer shells are typically not connected as a separate, discrete

part of the helmet (thus contrasting with the outer shell of the present invention).

Instead conventional helmets may be manufactured in moulds, into which the

material forming the impact absorbing layer is injected. In the present invention, the

Applicant has appreciated that the outer shell may also help to reduce the rotation

of the head of the user when the helmet is subject to an impact. Preferably the

outer shell is formed from a rigid material, such as a thermoplastic, e.g.

polycarbonate, or carbon fibre, or a composite material; however, it could be made

from any suitable and desired material. Preferable materials for forming the outer

shell have high strength to weight ratios.

In a preferred set of embodiments, the outer shell has a thickness that is

significantly less than a thickness of the impact absorbing layer. The outer shell

may thus comprise a membrane, e.g. at least partly covering the impact absorbing

layer. Thus, while the outer shell is designed to detach from the impact absorbing

layer when subject to an impact, the outer shell may itself not be designed to

absorb the force of the impact. Preferably, the outer shell has a thickness (e.g. in

the normal direction) of less than 6 mm, e.g. less than 4 mm, e.g. less than 2 mm,

e.g. less than 0.5 mm Different outer shell thickness may be advantageous for

different types of helmets, e.g. motorcyclist helmets may preferably have a thicker

outer shell (e.g. 6 mm), whereas bicycle helmets may have a thinner outer shell

(e.g. less than 4 mm).

Preferably the impact absorbing layer has a thickness (e.g. in the normal direction)

of between 10 mm and 50 mm, e.g. between 20 mm and 30 mm. Different impact

absorbing layer thickness may be appropriate for different types of helmets, e.g.

motorcyclist helmets may preferably have a thicker impact absorbing layer (e.g.

between 20 mm and 50 mm), whereas bicycle helmets may have a thinner impact

absorbing layer (e.g. between 10 mm and 30 mm).

In a preferred set of embodiments, the outer shell covers at least 60% of the

surface area of the outer surface of the impact absorbing layer, e.g. at least 70%,

e.g. at least 80%. The outer shell preferably covers the impact absorbing layer at

one or more, e.g. all, sites on the helmet which may experience an impact. The

outer shell may comprise one or more vent apertures to allow airflow. The outer

shell may not extend over the rim of the impact absorbing layer, when provided.

Thus for example, the outer shell may only extend over the outer surface of the

hollow cell structure. However, in other examples the shell extends at least partly

over the rim.

In a set of embodiments, the outer shell has a smooth outer surface, e.g. in which

the impact absorbing layer is formed from a plurality of cells. In a set of

embodiments, the inner surface of the outer shell is smooth. Such embodiments

may be advantageous as providing smooth surfaces enables the outer shell to

rotate over the impact absorbing layer with a minimized resistance upon impact.

The connecter is designed to retain the outer shell on the impact absorbing layer

(e.g. during normal use), and to allow the outer shell to separate from the impact

absorbing layer during an impact. This may allow the outer shell to move, e.g.

rotate, about the outer surface of the impact absorbing layer. This may be achieved

in any suitable or desired way. For example, the connector may be arranged to

retain the outer shell in position on the impact absorbing layer when weaker forces

act on the helmet (e.g. as would be expected in normal use), and allow the outer

shell to separate from the outer shell when larger forces act on the helmet, e.g. as the result of an impact. Preferably the connector extends in a radial direction, e.g.

perpendicular, to the surface of the impact absorbing layer (e.g. parallel to the walls

of the plurality of cells) and/or perpendicular to the surface of the outer shell.

In a set of embodiments, the connector is arranged to allow the outer shell to

separate from the impact absorbing layer when the (e.g. outer shell of the) helmet is

subject to an impact having a particular (e.g. predetermined) force (e.g. an oblique

force). This helps to retain the outer shell on the impact absorbing layer during

normal use and to separate from the impact absorbing layer when subject to an

impact. The particular force required for the connector to allow the outer shell to

separate from the impact absorbing layer may be chosen to have any suitable and

desired value (e.g. such that the outer shell only separates from the impact

absorbing layer as the result of a sufficiently large impact). In one embodiment the

particular (e.g. predetermined) force is between 10 and 100 N, e.g. between 30 N

and 70 N, e.g. approximately 50 N. The particular force may, for example be

chosen such that it reflects the lowest range of forces acting on the helmet which

may cause an injury.

The connector may be located at any suitable and desired position on the helmet.

However, preferably the connector is located along an axis of symmetry of the

helmet, e.g. along the mid plane of the helmet extending from the front to the rear of

the helmet. In a set of embodiments, the connector is located at the front of the

helmet. Positioning the connector at the front of the helmet may be particularly

useful in aiding the detachment of the outer shell in an oblique impact, particularly

for impacts that are offset from the central axis of symmetry and thus the front of

the helmet.

The connector may have any suitable and desired form, e.g. such that it is arranged

to allow the outer shell to separate from the impact absorbing layer when the

helmet is subject to an impact (e.g. having a force greater than a particular value

e.g. approximately 50 N). In a set of embodiments, the connector comprises a

discrete component from the outer shell and the impact absorbing layer. Thus

preferably at least a portion (e.g. the discrete component) of the connector is

arranged to detach from the impact absorbing layer and/or the outer shell when the

helmet is subject to an impact, e.g. such that the at least a portion (e.g. the discrete

component) of the connector is no longer in contact with the rest of the helmet, thus

allowing the outer shell to be separated from the impact absorbing layer.

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In one set of embodiments the connector comprises a plug which extends between

(and, e.g., is attached to both) the outer shell and the impact absorbing layer.

Preferably, the outer shell comprises an aperture for receiving the plug. Thus, for

example, the plug extends through the aperture and attaches to (e.g. a socket of)

the impact absorbing layer. The plug therefore may be accessible from the outside

of the outer shell. This may allow the plug to be easily removed to interchange the

plug and/or the outer shell. Interchanging the plug or the outer shell is particular

advantageous if either is damaged accidently or for aesthetic reasons.

Preferably the plug comprises an outer head having dimension(s) greater than the

corresponding dimension(s) of the aperture. The outer head of the plug may

therefore cover (e.g. encase) a portion of the outside of the outer shell. This may

further aid easier removal of the plug to interchange the plug and/or the outer shell.

The plug may attach to the impact absorbing layer in any suitable and desired way.

The plug may attach directly to the impact absorbing layer. For example, in

embodiments in which the impact absorbing layer comprises a hollow cell structure

(e.g. comprising a plurality of cells), the plug may attach directly into a cell of the

hollow cell structure of the impact absorbing layer.

In a preferred set of embodiments, the connector comprises a socket (e.g. clip) for

receiving the plug of the connector. Preferably the socket is formed on or attached

to the outer surface of the impact absorbing layer. Thus, when the outer shell is

mounted on and retained to impact absorbing layer, the plug is located in the

socket. Preferably, when the helmet is subject to an impact, the plug is arranged to

be removed from the socket, such that this allows the outer shell to separate from

the impact absorbing layer.

In one set of embodiments, the connector is an integrally formed part of the helmet

(e.g. of the outer shell and/or the impact absorbing layer). For example, the outer

shell and the impact absorbing layer may comprise complementary (e.g. male and

female) parts which (e.g. fit together to) form the connector. Thus, for example, the

outer shell may comprise a female (or male) member and the impact absorbing

layer may comprise a corresponding male (or female) member which connect

together to attach the outer shell to the impact absorbing layer. As outlined above,

for example, the male member may comprise a plug and the female member may comprise a complementary socket.

In a set of embodiments, the connector comprises a (e.g. hinged) projection (e.g. a

projecting latch). Preferably the projection is integral to (comprises part of) the

impact absorbing layer. Preferably, the projection is attached (e.g. integral) to the

main body of the impact absorbing layer by a flexible (e.g. hinged) portion.

Preferably the flexible portion is formed from the same material as (e.g. is integral

to) the impact absorbing layer.

The flexible (e.g. hinged) portion may be formed by a portion of material (e.g. a

"living hinge") that is thinner than the surrounding material (e.g. of the impact

absorbing later and/or the projection). The flexible portion allows the projection to

bend and/or deform (e.g. relative to the impact absorbing layer) when a force is

applied, e.g. without fracturing and/or rupturing the projection or its attachment to

the main body of the impact absorbing layer (via the flexible portion).

In a set of embodiments, the impact absorbing layer comprises a cavity arranged to

receive the projection, e.g. when the projection bends or deforms (e.g. via the

flexible portion) relative to the main body of the impact absorbing layer. This may

happen, for example, when a force is applied to the projection (e.g. via the outer

shell). Preferably the projection is arranged to bend and/or deform relative to the

main body of the impact absorbing layer, to allow the outer shell to separate from

the impact absorbing layer when the helmet is subject to an impact. Thus,

preferably, in normal use of the helmet, the cavity is empty and the projection

substantially does not protrude into the cavity.

Preferably, the outer shell comprises an aperture for receiving the projection (e.g. in

the manner of a latch). The projection and the aperture are preferably arranged

such that the projection extends through the aperture, e.g. when no force is applied

to the projection. Preferably the projection and the aperture are arranged to retain

the outer shell on the impact absorbing layer.

Preferably the projection and the aperture are arranged such that when a force is

applied to the projection (e.g. as a result of a force being applied to the outer shell)

the projection and the aperture move relative to (e.g. apart from) each other, allowing the outer shell to move relative to the impact absorbing layer. This may be owing to the projection being pushed into the cavity or the outer shell flexing away from the projection. Preferably this results in the projection no longer extending through the aperture in the outer shell.

This arrangement may help to retain the outer shell in a desired position on the

impact absorbing structure during normal use, while allowing (e.g. translational)

movement of the outer shell over the impact absorbing layer when the projection

has been moved into the cavity in the impact absorbing layer (e.g. owing to a force

being applied to the projection during an accident or by intentional means by a user,

such as to remove the outer shell from the impact absorbing layer).

In any of the embodiments described herein, the components of the connector may

attach to each other (and/or to the outer shell and/or impact absorbing layer) in any suitable or desired way, e.g. to provide them with an attachment requiring a

particular separation force (e.g. the particular force required to separate the outer

shell from the impact absorbing layer as outlined above).

For example, the plug and the (e.g. socket of the) impact absorbing layer may

attach together via a push (e.g. friction) fit. The push fit may be determined (e.g.

solely) by the dimensions of the plug (and, e.g., the socket). However, in one

embodiment, the plug and/or socket comprise one or more grips, ridges or latches.

The grips, ridges or latches may help to control (e.g. increase) the friction

therebetween and thus the force required to be exerted for the connector to allow

the outer shell to separate from the impact absorbing layer when the helmet is

subject to an impact.

The connector may be formed from any suitable and desired material. Preferably

the connector (e.g. the plug and/or socket) is formed from a rigid material such as

plastic, e.g. a thermoplastic, e.g. thermoplastic polyurethane (TPU), or a polyamide

(Nylon), e.g. laser sintered polyamide 11, or acrylonitrile butadiene styrene (ABS).

The connector (e.g. the plug and/or socket) may be formed of multiple parts which

may be fabricated from different materials, as appropriate. For example, as outlined

above, at least part of the connector may be integrally formed with (and thus

preferably formed from the same material from) the impact absorbing layer.

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In some embodiments the connector is arranged to separate into distinct parts or

break when the helmet is subjected to an impact, rather than to deform and absorb

energy when subjected to an impact. Preferably the plug is weaker than the outer

shell, such that the connector may detach before the shell fractures during an

impact.

The connector may be arranged to allow the outer shell to separate from the impact

absorbing layer as a result of an impact in any suitable and desired way.

Furthermore, the outer shell and the impact absorbing layer may be arranged to

separate from each other in any suitable and desired way. In a preferred

embodiment, e.g. when the helmet is subject to an oblique impact (such that

tangential and radial forces are exerted on the helmet), the outer shell is arranged

to be displaced relative to (e.g. rotated about) the impact absorbing layer.

Preferably the displacement of the outer shell causes the connector to disconnect

(e.g. the plug to be detached), e.g. owing to shearing forces.

The outer shell may be displaced relative to the impact absorbing layer in any

suitable and desired way. Preferably the outer shell is arranged to translate (e.g.

slide or rotate) relative to the impact absorbing layer when the helmet is subject to

an impact. Thus, preferably, apart from the connector (and, e.g. any further features

(e.g. as outlined herein) that help to locate the outer shell relative to the impact

absorbing layer), the outer shell is not fixed (e.g. glued, taped or attached

permanently by connectors) to the impact absorbing layer. This enables the outer

shell to be separated from the impact absorbing layer when the connector is no

longer connecting the outer shell to the impact absorbing layer. Thus preferably no

part which is integral to the (e.g. inner surface of the) outer shell (e.g. away from the

perimeter of the outer shell) is attached to the impact absorbing layer.

When subject to an impact that causes the outer shell to separate from the impact

absorbing layer, preferably the connector is arranged to allow the outer shell to

separate from the impact absorbing layer within 5 ms of the impact. Preferably the

outer shell and the impact absorbing layer are arranged to move, e.g. rotate,

relative to each other for between 10 and 15 ms when subject to an impact, e.g.

after the outer shell has separated from the impact absorbing layer.

While the helmet may comprise only one connector, in a set of embodiments the

helmet comprises a plurality of connectors that connect the outer shell to the impact

absorbing layer. The plurality of connectors may be identical or different. Preferably

the plurality of connectors are (together) arranged (e.g. together) to allow the outer

shell to separate from the impact absorbing layer when the helmet is subjected to a

particular (e.g. predetermined) force. Preferably the plurality of connectors are

located in respective different positions on the helmet. For example, the connectors

may be located at particular angles about the base of the outer shell, e.g. evenly

spaced from each other.

While the connector preferably provides the principal connection that connects the

outer shell to the impact absorbing layer to retain the outer shell on the impact

absorbing layer, the helmet may comprise one or more additional features which

aid the (correct) positioning and retention of the outer shell on the impact absorbing

layer. The (e.g. rim of the) impact absorbing layer may comprise at least one

groove or projection formed therein. In some embodiments the outer shell may

comprise at least one inwardly projecting ridge (e.g. clip).

Preferably the at least one ridge corresponds (e.g. in location) to and engages with

the at least one groove (or projection) in the (e.g. rim of the) impact absorbing layer

(e.g. in terms of location and dimensions), such that the ridge is located in the

groove (or on the projection), when the outer shell is mounted on the impact

absorbing layer. The at least one ridge may thus be located in the at least one

groove (when the outer shell is mounted on the impact absorbing layer), such that

there are additional attachment point(s) between the outer shell and the impact

absorbing layer than just the connector. The interconnecting ridge(s) and groove(s)

(or projection(s)) help to retain the outer shell in position during general use.

Preferably, the interconnecting ridge(s) and groove(s) (or projection(s)) provide a

weaker connection between the outer shell and the impact absorbing layer than is

provided by the connector. During an impact, when the connector disconnects the

outer shell from the impact absorbing layer, the at least one ridge is forced out of

position from its corresponding groove (or projection) such that the outer shell is

able to separate from the impact absorbing layer.

PCT/GB2020/051378

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Thus, in one embodiment, the ridge(s) and groove(s) (or projection(s)) are arranged

(e.g. interconnected when the outer shell is mounted on the impact absorbing layer)

such that a particular (e.g. predetermined) force is required to remove the ridge(s)

from the corresponding complementary groove(s) (or projection(s)). Preferably, this

particular (e.g. predetermined) force is less than the particular (e.g. predetermined)

force required for the connector to allow the outer shell to separate from the impact

absorbing layer when the helmet is subject to an impact. This helps to ensure that

once the force of an impact is sufficient to disconnect the connector between the

outer shell and the impact absorbing layer, to separate the outer shell from the

impact absorbing layer, the ridge(s) and groove(s) (or projection(s)) will preferably

also detach (or have already detached) from each other and will preferably not act

to provide any further resistance in retaining the outer shell on the impact absorbing

layer.

In some embodiments the (e.g. rim of the) impact absorbing layer comprises at

least one ridge and the outer shell comprises at least one groove (or projection), i.e.

the positioning of the ridge and the groove on the impact absorbing layer and the

outer shell are the opposite way around compared to the arrangement described

above. The features of the ridge(s) and groove(s) (or projection(s)) outlined herein

may apply equally to this embodiment.

The one or more grooves (or projections) and ridges may be located in any suitable

and desired positions around the (e.g. rim of the) impact absorbing layer and the

outer shell. In a set of embodiments, the groove(s) (or projection(s)) are equally

spaced about the (e.g. rim of the) impact absorbing layer. The one or more ridges

are preferably correspondingly located towards (e.g. at) the bottom edge (e.g. a

rim) of the outer shell. For example, complementary grooves (or projections) and

ridges may be located at the sides and rear of the helmet. Providing a plurality of

interconnecting grooves (or projections) and ridges allows the shell to be held more

securely in position on the impact absorbing layer, when the outer shell is mounted

on the impact absorbing layer during normal use.

In one embodiment, e.g. in addition to the ridge(s) and groove(s) (or projection(s))

outlined above, in order to help retain the outer shell in position on the impact

13 Mar 2026

absorbing layer during normal use, the impact absorbing layer may comprise at least one protrusion on its outer surface. When the impact absorbing layer comprises a plurality of protrusions, preferably the protrusions are evenly spaced around the outer surface of the impact absorbing layer. In this embodiment, preferably the outer shell 5 comprises at least one recess corresponding (and complementary) to the at least one protrusion of the impact absorbing layer. Thus, when the outer shell is located on the 2020286992

outer surface of the impact absorbing layer, the at least one protrusion on the impact absorbing layer interconnects with the at least one corresponding recess.

Preferably, the complementary protrusion(s) and recess(es) are provided (only) to 10 help locate the outer shell in its correct position on the impact absorbing layer. Thus preferably, the complementary protrusion(s) and recess(es) provide a (e.g. significantly) weaker connection between the outer shell and the impact absorbing layer than is provided by the connector (and, e.g., by the complementary groove(s) (or projection(s)) and ridge(s)). During an impact, when the connector disconnects 15 the outer shell from the impact absorbing layer, the protrusion(s) and recess(es) move apart from each other such that the outer shell is able to separate from the impact absorbing layer.

Thus, in one embodiment, the complementary protrusion(s) and recess(es) are arranged such that a particular (e.g. predetermined) force is required to displace the 20 protrusion(s) from the complementary recess(es). Preferably, this particular (e.g. predetermined) force is (e.g. significantly) less than the particular (e.g. predetermined) force required for the connector to allow the outer shell to separate from the impact absorbing layer when the helmet is subject to an impact. This helps to ensure that once the force of an impact is sufficient to disconnect the connector 25 between the outer shell and the impact absorbing layer, to separate the outer shell from the impact absorbing layer, the complementary protrusion(s) and recess(es) will preferably also be displaced (or have already been displaced) from each other and will preferably not act to provide any further resistance in retaining the outer shell on the impact absorbing layer.

30 In a broad sense, the present invention as claimed provides a helmet comprising: an impact absorbing layer; a detachable outer shell mounted on an outer surface of the impact absorbing layer; and

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MARKED-UP COPY a connector which detachably connects the outer shell to the impact absorbing layer to retain the outer shell on the impact absorbing layer, wherein the connector is arranged to allow the outer shell to completely detach from the impact absorbing layer when the helmet is subject to an impact 5 having an oblique force between 10 and 100 N. 2020286992

The term “comprise” and variants of the term, such as, e.g., “comprises” or “comprising” are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context of usage an exclusive interpretation of the term is required.

10 An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[Text continues on page 13]

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Figure 1 shows a front exploded view of a helmet according to an

embodiment of the present invention;

Figure 2 shows a rear exploded view of the helmet shown in Figure 1;

Figure 3 shows a front view of the helmet shown in Figures 1 and 2;

Figure 4 shows a cross-section view of the helmet shown in Figures 1, 2 and 3;

Figure 5 shows a front view of the helmet shown in Figures 1 to 4 during an

oblique impact;

Figures 6A, 6B and 6C show a selection of views of a plug for use in the

helmet; and

Figure 7 shows a cross-section view of a portion of a helmet according to

another embodiment of the present invention.

A helmet acts to protect a user's head from injury by absorbing energy from an

impact. Oblique impacts, which are a common type of impact, may subject a helmet

to significant tangential forces. Such forces have the potential to cause rotational

acceleration of the user's brain, which may cause serious brain injuries.

Embodiments of the present invention aim to provide an improved helmet that

seeks to mitigate the effect of such oblique impacts.

Figures 1 to 5 show different views of a helmet 100 according to an embodiment of

the present invention. Both Figures 1 and 2 show an exploded view of the helmet to

demonstrate the different components of the helmet 100 clearly. Figure 1 shows a

view directed towards the front of the helmet 100. Figure 2 shows a view directed

towards the back of the helmet 100. The helmet 100 has the following principal

components: an impact absorbing layer 102, an outer shell 104 and a plug 106.

The impact absorbing layer 102 is predominately formed of an out-of-plane

honeycomb structure. The impact absorbing layer 102 further comprises a rim 108

around the base of the helmet 100. The rim 108 is formed from a solid (e.g. non-

hollow) material such as expanded polystyrenes in contrast to the out-of-plane

honeycomb structure 102 which formed of hollow cells, the tessellating cells having

a hexagonal cross section.

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The rim 108 of the impact absorbing layer 102 further includes a set of grooves

116, into which ridges 118 on the lower edge of the outer shell 104 (as can be seen

in Figure 2) fit. These interlocking grooves 116 and ridges 118 help to retain the

outer shell 104 in position on the impact absorbing layer 102 during normal use.

Figure 2 also shows an additional protrusion 124 on the impact absorbing layer 102

mounted on the rear of the helmet. The protrusion 124 interconnects with a

corresponding recess 126 on the outer shell 104, and further helps to retain the

outer shell 104 in position on the impact absorbing layer 102 during normal use.

As can be seen from Figure 1, a socket 114 is attached to the outer surface of the

impact absorbing layer 102 into which the plug 106 fits. The plug 106 and the

socket 114 fit together via a push (e.g. friction) fit. Together, the plug 106 and the

socket 114 form a connector that connects the impact absorbing layer 102 and

outer shell 104 together to retain the outer shell 104 on the impact absorbing layer

102 during normal use.

The outer shell 104 includes an aperture 110 at the front of the helmet through

which the plug 106 can be inserted when the outer shell 104 is positioned on the

impact absorbing layer 102. To fit together the plug 106, the outer shell 104 and the

impact absorbing layer 102, the outer shell 104 is first positioned on the impact

absorbing layer 102. This involves interlocking the side grooves 116 and

corresponding complementary ridges 118, as well as the rear protrusion 124 and

the interconnecting recess 126.

When the outer shell 104 is correctly positioned on the impact absorbing layer 102,

the aperture 110 in the outer shell 104 is aligned with the socket 114. The plug 106

can then be inserted through the aperture 110 and into the socket 114. A front view

of the helmet 100, with the plug 106 inserted and holding the outer shell 104 in

position, is shown in Figure 3. Figure 4, which shows a cross section view of the

helmet 100 in a plane along the central axis of symmetry of the helmet 100, shows

the plug 106 in position extending through the outer shell 104 and into the socket

114 on the impact absorbing layer 102.

Figure 3 also shows recesses 122 in either side of the inner surface of the outer

shell 104. In Figure 5, the corresponding protrusions 120 on the outer surface of the

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15 -

impact absorbing layer 102 are seen, as well as the recesses 122 in the outer shell

104. When the outer shell 104 is positioned correctly on the impact absorbing layer

102, the protrusions 120 fit into the recesses 122, acting to help locate and retain

the outer shell 104 on the impact absorbing layer 102.

Figure 5 demonstrates the reaction of the helmet 100 shown in Figures 1 to 4 in an

oblique impact. In Figure 5 the helmet 100, which is attached to the head of a user

who is falling downwards, has been subject to a collision with the obstacle 502. The

edge of the obstacle 502 which the helmet 100 contacts during the collision is

slanted, and contacts the helmet 100 at a position which is offset from the centre of

the helmet 100, which results in the force exerted on the helmet from the impact

having a significant tangential component.

In the impact shown in Figure 5, the force exerted upon the helmet 100 during the

impact is larger than the particular force which is required to detach the plug 106

from the socket 114, so to allow the outer shell to separate from the impact

absorbing layer 102. Therefore, upon impact with the obstacle 502, the plug 106 is

ejected from the helmet 100; specifically ejected from the socket 114 on the impact

absorbing layer 102. As seen in Figure 5, the plug 106 completely separates from

the helmet 100. However, there may be other embodiments not shown in which the

plug 106 remains in contact with at least part of the helmet 100 whilst still allowing

the outer shell 104 to separate from the impact absorbing layer 102.

Upon impact with the obstacle 502, the interconnecting recesses 122 and

protrusions 120, the interconnecting grooves 116 and ridges 118, and the

interconnecting protrusion 124 and recess 126 also become disconnected from

each other. There are therefore no remaining features which connect the outer shell

104 to the impact absorbing layer 102. The outer shell 104 is then able to rotate on

the impact absorbing layer 102. This rotation is caused by the tangential component

of the force exerted on the helmet 100 upon impact with the obstacle 502. The

outer shell 104 rotating independently of the impact absorbing layer 102 (and

ultimately the head of the user) reduces the rotation of head of the user, which may

reduce the injuries sustained from the impact.

The Applicant has found that helmets according to embodiments of the present

invention may reduce the rotational acceleration and velocity experienced the head

of a user, compared to conventional foam helmets, by approximately 25% (in

rotational acceleration) and approximately 45% (in rotational velocity).

Figures 6A, 6B and 6C show various views of the plug 106. As can be seen in

these Figures, the plug 106 comprises an outer head 602. The outer head 602 has

an area greater than that of the aperture 110 into which the plug fits. After insertion

of the plug 106 through the aperture 110 and into socket 114, the outer head 602

sits outside of the outer shell 104 as seen in Figure 3.

The plug 106 further comprises a neck 604, which is connected to the outer head

602. In examples in which the plug 106 and the socket 114 fit together via a push

(e.g. friction) fit, the neck 602 may be made from a deformable plastic such that the

neck 602 of the plug 106 can be inserted into the socket 114. The neck 604 has

ridges 606 which act to hold the plug 106 in position in the socket 114. The socket

may comprises corresponding grooves which mate with the ridges 606 of the plug

106 when the plug 106 is inserted into the socket.

Figure 7 shows a cross-sectional view of a portion of a helmet 700 according to

another embodiment of the present invention. The helmet 700 has the following

principal components: an impact absorbing layer 702, an outer shell 704 and a latch

706. The latch 706 may be positioned in a similar location as the plug shown in

previous figures.

The latch 706 is integral to (e.g. formed from the same material as) the impact

absorbing layer 702. The latch 706 includes a flexible portion 708 that attaches the

latch 706 to the main body of the impact absorbing layer 702. The flexible portion

acts as a living hinge to allow the position of the latch 706 to change relative to the

main body of the impact absorbing layer 702 and the outer shell 704. The latch 706

also includes a block tip 707.

The impact absorbing layer 702 additionally includes a cavity 714. When a force is

applied to the latch 706, the flexible portion 708 bends, which may move the latch

706 into the cavity 714.

The outer shell 704 includes an aperture 705. During normal use (e.g. not during an

accident), the latch 706 extends through the aperture 705. The block tip 707 of the

latch 706 helps to keep the outer shell 704 in position on the impact absorbing layer

702 during normal use, by interacting with the edges of the aperture 705 to prevent

translational movement of the outer shell 704 with respect to the impact absorbing

layer 702.

Upon impact with an obstacle (e.g. similar to that seen in Figure 5), the force of the

impact acts on the flexible portion 708 of the latch 706, causing the flexible portion

708 to bend. The direction in which the flexible portion 708 is bent may depend on

the direction of the tangential forces acting on the helmet upon impact.

In an impact in which the tangential forces act in the direction shown by arrow 730,

i.e. the impact force acts downwards, as the outer shell 704 rotates downwards it

moves over the latch 706 and the latch 706 is pushed into the cavity 714. This

allows the outer shell 704 to detach from and move over the impact absorbing layer

702, helping to reduce the tangential forces transferred to the head of the user.

In an impact in which the tangential forces act in the direction shown by arrow 740,

i.e. the impact force acts upwards, as the outer shell 704 rotates, the edge of

aperture 705 of the outer shell 704 engages against the block tip 707 of the latch

706. The force exerted on the latch 706 either moves the latch 706 into the cavity

714, or rotates the latch 706 away from the cavity 714 and back on itself. Either of

these movements of the latch 706 allows the outer shell 704 to detach from and/or

move obstruction free over the impact absorbing layer 702, helping to reduce the

tangential forces transferred to the head of the user.

In an impact in which the tangential forces act in another direction to that shown by

arrows 730, 740, both of the abovementioned mechanisms may occur (e.g. at least

in part) in order to enable the separation of the outer shell 704 and the impact

absorbing layer 702.

In general, the latch 706 shown in Figure 7, is able to maintain its functionality after

an impact. For example, in an impact in which the latch 706 is merely compressing into the cavity 714 such that the outer shell 704 can move freely on the impact absorbing structure 702, after the impact the original (or a new) outer shell 704 may be repositioned on the impact absorbing structure 702.

The latch 706 may also be manually compressed into the cavity 714 by a user, e.g.

to allow for easy intentional removal the outer shell 704. This may allow the outer

shell 704 to be interchangeable, for example for aesthetic purposes.

Thus it will be appreciated by those skilled in the art that a helmet according to

embodiments of the present invention, in which two independent layers (the outer

shell and impact absorbing layer) connected by a connector, which allows the

layers to separate when the helmet is subject to an impact, helps to reduce the

tangential forces that may be transferred from an oblique impact to the head of the

user. This may provide significant benefits over known helmets, e.g. in helping to

reduce brain injuries. It will further be appreciated however that many variations of

the specific arrangements described herein are possible within the scope of the

invention. For example, a different type of connector (as opposed to a plug and

socket and arrangement) may be provided to connect the outer shell to the impact

absorbing layer.

Claims (20)

13 Mar 2026 CLAIMS

1. A helmet comprising: an impact absorbing layer; a detachable outer shell mounted on an outer surface of the impact absorbing 5 layer; and 2020286992

a connector which detachably connects the outer shell to the impact absorbing layer to retain the outer shell on the impact absorbing layer, wherein the connector is arranged to allow the outer shell to completely detach from the impact absorbing layer when the helmet is subject to an impact 10 having an oblique force between 10 and 100 N.

2. The helmet as claimed in claim 1, wherein the impact absorbing layer comprises a hollow cell structure.

3. The helmet as claimed in claim 1 or claim 2, wherein the outer shell is formed from a rigid material.

15 4. The helmet as claimed in any one of claims 1 to 3, wherein the outer shell has a thickness of less than 6 mm, less than 4 mm, e.g. less than 2 mm, e.g. less than 0.5 mm.

5. The helmet as claimed in any one of claims 1 to 4, wherein the connector is located along an axis of symmetry of the helmet.

20 6. The helmet as claimed in any one of claims 1 to 5, wherein the connector is located at the front of the helmet.

7. The helmet as claimed in any one of claims 1 to 6, wherein the connector comprises a discrete component from the outer shell and the impact absorbing layer.

8. The helmet as claimed in any one of claims 1 to 7, wherein at least a portion 25 of the connector is arranged to detach from the impact absorbing layer and/or the outer shell when the helmet is subject to an impact.

9. The helmet as claimed in any one of claims 1 to 8, wherein the connector comprises a plug which extends between the outer shell and the impact absorbing layer.

13 Mar 2026

10. The helmet as claimed in claim 9, wherein the outer shell comprises an aperture for receiving the plug.

11. The helmet as claimed in claim 9 or claim 10, wherein the connector comprises a socket for receiving the plug of the connector.

5

12. The helmet as claimed in claim 11, wherein the socket is formed on or 2020286992

attached to the outer surface of the impact absorbing layer.

13. The helmet as claimed in claim 11 or claim 12, wherein the plug and the socket attach together via a push fit.

14. The helmet as claimed in any one of claims 9 to 13, wherein the plug 10 comprises an outer head having dimension(s) greater than the corresponding dimension(s) of the aperture.

15. The helmet as claimed in any one of claims 1 to 8, wherein the connector comprises a projection and that is integral to the impact absorbing layer.

16. The helmet as claimed in claim 15, wherein the projection is attached to the 15 main body of the impact absorbing layer by a flexible portion .

17. The helmet as claimed in claim 15 or claim 16, wherein the impact absorbing layer comprises a cavity arranged to receive the projection.

18. The helmet as claimed in any one of claims 15 to 17, wherein the outer shell comprises an aperture for receiving the projection.

20

19. The helmet as claimed in any one of claims 1 to 18, wherein the impact absorbing layer comprises at least one groove formed therein, wherein the outer shell comprises at least one inwardly projecting ridge, and wherein the at least one ridge is arranged to engage with the at least one groove when the outer shell is mounted on the impact absorbing layer.

25

20. The helmet as claimed in claim 19, wherein the at least one ridge and the at least one groove are arranged such that a particular force is required to remove the at least one ridge from the at least one groove.

13 Mar 2026

21. The helmet as claimed in any one of claims 1 to 20, wherein the connector extends in a radial direction to the impact absorbing layer.

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WO 2020/245609 2020/24569 OM PCT/GB2020/051378 PCT/GB2020/051378

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