EP4329552A1

EP4329552A1 - Impact absorbing structure

Info

Publication number: EP4329552A1
Application number: EP22721832.8A
Authority: EP
Inventors: Christopher Bill BRUCKNER
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-04-28
Filing date: 2022-04-27
Publication date: 2024-03-06
Also published as: WO2022229630A1; GB2606179A; US20240206582A1; GB202106056D0; CN117529251A; AR125463A1

Abstract

A protective helmet impact-absorbing structure, comprising: at least one elongate tapering member (10) formed unitarily from foam, comprising: a base portion; a top portion; and at least one side portion extending in a tapering manner therebetween; wherein the at least one elongate tapering member is arranged for operative location between an inner shell (20) and an outer surface (21) of the helmet.

Description

Impact Absorbing Structure

Field of the Invention

The present invention relates to developments and improvements in the field of protective equipment, and particularly personal protective equipment.

Background

In the field of protective equipment and in particular personal protective equipment, impact-absorbing structures for use in containers, bodywear or helmets is well developed and many solutions have been found for the dissipation of high energy impacts to reduce damage to a user.

Such impact-absorbing structures commonly employ a closed-cell rigid foam, such as Expanded Polystyrene, structure with an outer rigid layer. These structures are effective in dissipating incident force above a given threshold by allowing the foam structure to permanently deform or fracture, thereby absorbing the energy of the impact. However, such structures often store and then release energy from impacts in the form of a ‘rebound’ or ‘springback’ action which may cause further significant injury.

An example of an alternative approach to such a structure is provided in document US2017196291A, which describes a helmet worn by a wearer having an exterior shell and an interior shell with impact absorbing material comprising various structures between the exterior shell and the interior shell. When force is applied to the exterior shell, the structures of the impact absorbing materials deform (e.g., compress), reducing the force received by the interior shell. For example, the impact absorbing material forms structures such as multiple branched Ύ” shapes or multiple cylindrical rods with a surface contacting the exterior shell and a surface contacting the interior shell. The interior of the rods and other impact absorbing structures may be filled with a deformable material, such as foam. The impact absorbing material are formed into jacks, spherical shapes, bristles, intersecting arches, or other shapes positioned between the exterior shell and the interior shell. These structures are configured such that the external element of each structure is more rigid than the foam they contain, and as such does not account for dissipation of a force that induces a rotation of the helmet, such as a ‘glancing’ impact or an impact with a non normal component to the helmet surface. Such a force exerted on this design would transmit substantial force to the user’s head. Such structures, although effective, are configured to dissipate impacts that result in compression of the helmet between the user’s head and an incident object - hereafter referred to as a ‘compressive’ force. Not addressed by these structures are impacts that cause a rotation of the helmet via impacts comprising non-normal component forces to the helmet surface, more than a compression of the helmet, for example an impact that is substantially perpendicular to the surface of the helmet. In such an impact, the force is not efficiently dissipated through the foam which is configured to fracture or deform under a compressive load and the helmet tends to rotate, thus rotating the users head. Such sudden rotation can result in brain injuries of similar or worse severity than the equivalent energy delivered in a ‘compressive’ impact.

It is a result of recent scientific studies that low-energy and/or frequent impacts to a user’s head can result in alterations to the white and grey matter of the brain (‘Brain damage risk for children after three rugby games’ - Tom Ball, The Times 19 June 2020).

To address this deficiency in dissipation of rotational energy, a prominent solution known as MIPS (RTM) has been developed. This solution disposes a low friction ‘liner’ between the user’s head and the helmet, allowing the helmet to rotate through small angles independently of the user’s head. In doing so, the helmet rotates through a small angle which may be enough to orient the helmet to dissipate the impact as a compressive, rather than rotational force. However, the low friction liner is composed of a high density material that is difficult to compress. Thus the MIPS (RTM) solution does not provide any directly attributable additional dissipation of an impact force.

Such a solution is described by document GB249257A, which describes a liner assembly for a helmet including an energy dispersing liner comprising a sheet of thermoset polymer adapted to be received in a helmet outer shell. The liner assembly further comprises a layer of padding connectable between the sheet of thermoset polymer and the helmet outer shell. The polyurethane energy dispersing liner comprises deformable protrusions, preferably in the form of 'pyramids' which act as a 'suspension' system. These deformable pyramids are provided on the liner where an air gap will exist between the liner assembly and the shell of a helmet incorporating the liner assembly. Such a solution partially addresses compressive impacts and impacts that result in rotation of the helmet, but the range of motion is limited.

A further solution is presented in document US2013340150A, which discloses a number of airbag-type structures mounted on the inside of the outer surface of a helmet. Each of the airbag-type structures contains a shaped polyurethane block and has a plurality of air escapement openings 18, 20 and 21 sized to meter the release of air under impact to the helmet outer shell. A predetermined pressure is required for each layer which is different for each air bag layer. Such a design allows for compression of the helmet, but does not account for rotational displacement of the outer shell.

Aspects and embodiments of the invention have been devised with the foregoing in mind.

Summary of the Invention

In an embodiment of the invention, a protective helmet impact-absorbing structure is provided, comprising at least one elongate tapering member formed unitarily from foam. The elongate tapering member comprises a base portion, a top portion, and at least one side portion extending in a tapering manner therebetween. The at least one elongate tapering member is arranged for operative location between an inner shell and an outer surface of the helmet.

The elongate tapering member is capable of flexing laterally either uncompressed or under compression. This can be achieved by the composition of the elongate tapering member being that of one foam component. By having a tapered profile, the member is able to freely flex laterally in response relative translation of the top and bottom portions without impeding the freedom of an adjacent elongate tapering member either compressed or uncompressed. Thereby a structure capable of absorbing torsional and compressive impacts contemporaneously is provided.

The narrow end of the elongate member is more readily compressible than the wide end by virtue of the elongate member having a unitary composition. The elongate member is therefore more readily compressible enabling dissipation of smaller forces by deformation of the narrow end. As discussed above and in the cited publication ‘Brain damage risk for children after three rugby games’, dissipation of such small forces is required to prevent brain injury. It is an object of the invention that such small impacts are readily dissipated. In some embodiments the protective helmet impact-absorbing structure can further comprise an inner shell. The provision of an inner shell enables a secure interface between the elongate tapering member and the head of a user.

In some embodiments, the protective helmet impact-absorbing structure can further comprise an outer surface. The outer surface enables the distribution of forces incident upon the helmet impact-absorbing structure between the one or more elongate tapering members. Through the interaction of the outer surface, inner surface and elongate tapering members, the inner shell may translate rotationally and linearly relative to the outer surface thereby dissipating energy in the elongate tapering members.

In some embodiments, the at least one elongate tapering member can be affixed to the inner shell at the base portion or at a top portion. By affixing the elongate tapering members to the inner shell, a more robust structure is provided.

In some embodiments, the at least one elongate member can be affixed to the outer surface at the bottom portion or top portion, such that the other respective portion is attached to the inner shell. By affixing the outer surface to the elongate members which are themselves affixed to the inner shell, a maximum limit for relative translation of the inner shell and outer surface is established.

In some embodiments the base portion of the elongate tapering member can include or comprise a recess, which in some embodiments may be a blind bore in the centre of the base portion. By reducing the volume of the foam of a tapering member, the mass of the impact-absorbing structure is reduced thereby reducing strain on the user.

In some embodiments, the elongate tapering member can be formed from a closed or open-celled memory foam, or low springback foam. Such a foam is capable of being compressed from a low density to a high density without permanent alteration of the structure of the foam, thus making the foam reversibly compressible. By using such a foam in the construction of the elongate tapering member, the member is capable of extensive reversible deformation. Such foams are also capable of dissipating high energy impacts via compression of the foam, instead of transmitting the force through the foam.

In some embodiments, the memory foam can exhibit a low springback rate.

An ascribed benefit of such a property is that although reversibly deformable, the elongate tapered member will not return to its uncompressed shape quickly, thereby minimising any rapid relative translation of the inner shell and outer surface after an impact or compression.

In some embodiments at least one elongate tapering member may be generally frusto-conical in shape. Such a shape provides equal resistance to translation of the top and bottom portions in each direction orthogonal to the length of the elongate tapering member. That is to say, any direction substantially perpendicular to the to the axis of rotational symmetry of the elongate member, or simply ‘side-to-side’.

In some embodiments at least one elongate tapering member may be generally pyramidal in shape. Such a shape provided non-uniform resistance to translation of the top and bottom portions in each direction orthogonal to the length of the elongate tapering member.

In some embodiments, the impact absorbing structure can comprise at least two elongate tapering members. Provision of at least two elongate tapering members allows control of the properties of the impact-absorbing structure by placement of the elongate tapering members.

In some embodiments, the structure can comprise at least one elongate tapering member with a generally frusto-conical shape, and at least one elongate tapering member with a generally pyramidal shape. This allows different regions of the helmet to be biased against deformation in specified directions, or not biased as may be required.

In some embodiments, a spacing between the elongate members may be uniform, to ensure a uniform dissipation of incident impact energy.

In some embodiments, a spacing between the elongate members may be varied to increase or decrease local resistance to deformation of the elongate members in response to an incident force. Thus, an impact absorbing structure according to the present invention may be configured to provide more protection from impacts in desired directions, and less protection in others.

In some embodiments, the inner shell may be formed of a rigid or semirigid material. The inner shell thereby provides an additional layer of protection against any penetrating objects during an impact, or crushing forces.

In some embodiments, the outer surface is formed of a rigid or semirigid material. The outer surface thereby provides an additional layer or protection against sharp objects in an impact. In some embodiments, a helmet is provided comprising an impact-absorbing structure in accordance with the present invention.

Incorporation of the impact-absorbing structure of the present invention into a helmet may provide a user with enhanced protection from impacts.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which:

Fig 1 depicts an exemplary embodiment of an elongate tapering member.

Fig 2A depicts an exemplary embodiment of an elongate tapering member comprising a top portion and a base, formed unitarily from foam under a low compressive load FY and shear load Fx.

Fig 2B depicts an exemplary embodiment of an elongate tapering member formed unitarily from foam under a higher compressive load FYI and shear load Fxi.

Fig 3 depicts an exemplary embodiment of an impact-absorbing structure according to the present invention, wherein the inner shell and outer surface are subject to a linearly compressive force, and showing the deformation of a plurality of elongate tapering members.

Fig 4 depicts an exemplary embodiment of a helmet comprising an impact absorbing structure according to the present invention, comprising an outer surface , an inner shell, and elongate members.

Fig. 5A depicts an exemplary embodiment of a helmet with a resiliently deformable outer surface deforming under vertical load F .

Fig. 5B depicts an exemplary embodiment of a helmet with a resiliently deformable outer surface deforming under radial load F_r.

Fig. 6 depicts an incident force F that results in a relative rotation R of the inner shell relative to the outer surface under compression.

Fig. 7A depicts an exemplary embodiment further comprising a further impact absorbing layer and outer surface.

Fig. 7B depicts an exemplary embodiment further comprising a supplementary impact absorbing layer and inner shell.

Detailed Description

As depicted in Figs 2A and 2B, an elongate tapering member 10 formed unitarily from foam is capable of resiliently deforming in multiple directions at the same time. It is a feature of the present invention that the design of the elongate tapering members allows deformation in response to force Fx even whilst deforming in response to force FY. This deformation allows energy to be dissipated by relative translation of each end of the elongate member in any direction. It is a further feature of the elongate member that under compression FY, the horizontal expansion of the member beyond its widest uncompressed point is minimised. This is achieved by the tapered shape of the member. Thus there is provided an elongate member that not only is capable of deforming in multiple directions, but in which the deformation in one direction (vertically in Fig. 2B) in response to force FYI does not restrict the deformation of the same member in a second direction (horizontally in Fig. 2B) in response to force Fxi. By affixing or placing an outer surface 21 to/at one end, and an inner shell 20 to/at the other, a protective impact-absorbing structure is provided. In some embodiments, the elongate members taper according to expected forces, for example by a 0.1% - 10% gradient, a 10.1% - 20% gradient, or a 20.1% - 30% gradient. These gradients are examples only, and it is expected that other gradients may be selected to accommodate forces expected in each use-case.

In one embodiment, an impact absorbing structure is provided comprising an inner shell 20, a plurality of elongate tapering members, and an outer surface 21.

The elongate members are affixed to the inner shell 20 at a top portion 11 , and are spaced uniformly. The bottom portion 12 of each elongate member is affixed to the interior of the outer surface 21. The elongate members are affixed at each of their ends using a strong glue, such as a contact adhesive. Preferably, the widest point of each elongate member is positioned according to expected forces. For example, it may be desirable to position the widest point of each elongate member a minimum of 1mm-10mm apart in one use-case, or 1cm-10cm apart in another.

The inner shell 20 is configured to be placed around a users head, and optionally is fitted with fabric or soft foam members for the user’s comfort. The impact absorbing structure is further provided with a means to secure the impact absorbing structure to a user’s head. This may be achieved using fabric straps, for example.

The elongate tapering foam members are formed from so-called ‘memory foam’, a closed-celled or open-celled foam with a low springback rate. Such foams are reversibly compressible to a high degree, and so are capable of returning to their original form after high compression. The foam is resistively compressible so as to ensure that energy is appropriately dissipated by deformation of the foam member. The use of a foam with a low springback rate results in a further advantage in that any impact that results in a torque that causes a brain injury will not be exacerbated by the foam exerting a strong ‘restoring’ force. For example, should a simple ‘spring’ be used, the brain would receive injury from the initial torque that rotated the user’s head, and then the spring would accelerate the user’s head back in the opposite direction. If the spring is sufficiently powerful, this could result in a second subsequent torque sufficient to cause a brain injury. It is known that small impacts and small torques have the potential to cause significant brain injury, and so the simple ‘spring’ of the above example would not need to be particularly strong to cause injury on ‘springback’.

By the use of multiple members, the resistance of the impact absorbing structure to deformation and therefore rigidity of the impact absorbing structure is increased. Preferably, the size and spacing of the elongate foam members is selected to optimise the resistance to deformation of the impact-absorbing structure for the appropriate activity for which it is intended. For example, for low-energy impacts it would be preferable that the impact-absorbing structure was less rigid such that the energy is more readily dissipated by deformation of the foam members. Conversely, for high-energy impacts such a configuration may be inappropriate in that the foam members may deform too readily. In such a situation the use of fewer elongate members, therefore reducing the average density of the impact-absorbing structure, reduces the maximum possible dissipated energy. To adjust for this, more elongate members may be used, placed closed together, larger elongate members may be used, and/or a more rigid foam may be selected.

By altering the width of an elongate member, the resistance to ‘shear’ forces, i.e. forces that result in rotation of the outer surface relative to the inner shell, is altered. In some embodiments, it may be advantageous to decrease resistance to rotational forces by implementing narrower elongate members, whilst maintaining resistance to compressive forces by increasing the number of elongate members used. In a preferred embodiment, the maximum width of the elongate member is selected according to expected impact force. For example, the maximum width of each elongate member may be between 0.5cm - 1.5 cm, 1 6cm - 2.5cm, or 2.6cm - 3.5cm as required by the use-case. Different spacings or widths / lengths of the elongate members may be selected for placement in various locations in an impact-absorbing structure to alter the properties of the structure according to requirements. For example, a structure may be configured such that when used in a helmet, there is more resistance to deformation at the temples than at the crown, in an environment where impacts are more likely to come from the side than above.

It is an object of the present invention that the shape of the elongate members allows relative rotation of the outer surface relative to the inner shell, whilst dissipating rotational energy exerted on the outer surface. This is achieved by shaping the elongate members such that under compression, the body of the members do not impinge upon each other, by tapering away from one another as a function of their length. Thus when the inner shell and outer surface are displaced relative to one another, the members are able to flex, compress and extend as required to allow this movement but will dissipate energy as they do so. Such a relative displacement, such as translation or rotation, can be seen in Fig. 3. In Fig. 3. The undisturbed, or ‘neutral’ placement of the inner shell and elongate members is shown by the dashed lines. A compression is exerted on the inner shell and outer surface, such that the inner shell moves toward the outer surface as shown. A deformation of the elongate members is observed, shown as black and white members. As depicted, the elongate members are spaced close together but their shape results in minimal outward expansion when compressed. Accordingly, when the elongate members are forced to ‘bend’ by a searing force, they do not restrict the compression or deformation of their neighbouring members. This is achieved by not occupying the space into which each member must expand under compression.

When a deformable cylinder is axially compressed and experiences a relative radial translation of the top and bottom of the cylinder, there will come a point at which the top has translated sufficiently that a vector representing the average location and direction of the axial load no longer passes through the ‘base’ of the cylinder, and so the cylinder, being deformable, will ‘buckle’ or ‘give way’. This ‘buckling’ results in some section or part of the length of the cylinder being displaced such that the vector no longer travels along its length, thus resulting in a large reduction in resistance to deformation of the cylinder in the axial direction. Such buckling is avoided by using a tapering member. In Fig. 6 relative rotational translation R of the inner shell 20 and outer surface 21 in response to an impact F , where the dashed lines indicate undisturbed placement of the elongate members and inner shell. The same buckling effect is a feature of impact absorbing structures which are formed of non-deformable media, in that these structures are configured to dissipate energy by buckling in a non-reversible manner.

A tapering elongate member is further enhanced in that such radial deformation (in response to a relative translation of the top and bottom portions of the member corresponding to a relative rotation of the inner shell and outer surface) can be performed without ‘buckling’ of the member, in that when sufficiently tapered, the thinner of the base or top of the member cannot translate outside of the ‘footprint’ of the wider of the base or top enough such that a vector representing the average location and direction of the axial load is positioned to create a ‘buckling’ effect.

Furthermore, as a result of the tapered shape of the elongate members, there is a reduced resistance to rotation. In some embodiments, the elongate members are configured to be pyramidal such that the axially, the thickness of a given elongate member is non-uniform. This results in a resistance to translation deformation, or bending, in some directions more than others.

Such a configuration means that the impact-absorbing members may be employed to dissipate more rotational energy in some directions than others. For example. It may be advantageous to increase the energy required to displace the outer surface and inner structure when a helmet containing the impact-absorbing structure is rotated according to a ‘nod’ and ‘shake your head’ style motion, to avoid unwanted movement of the helmet during normal use. Such a configuration would however maintain a lower energy threshold for deformation in other axes of rotation.

The tapered shape of the elongate members results in a resistance to axial deformation that varies non-linearly with extension or compression of the member. That is to say, due to the tapering of the member, Flooke’s law does not hold across the entire range of compression for the elongate member. This is because as the member is compressed, the narrow end of the member will compress more readily than the wider end. As this compression continues, more of the ‘width’ of the member will be recruited into resisting the compression as the top or bottom portion encroaches on the middle of the member. This non-linear resistance to compression enables the impact absorbing structure to dissipate both small and large impacts, in contrast to existing methods with a uniform or linear response to compression, which are configured to dissipate one or the other. In some embodiments, the outer surface may be semirigid or resiliently deformable, as depicted in Fig. 5A and Fig. 5B. Provision of such an outer surface may allow more dissipation of energy from both ‘glancing’ impacts F that induce a rotation R of the outer surface 21 relative to the inner shell 20, and radial impacts F_r. In this figure, the dashed lines indicate the undisturbed placements of the elongate members and the outer surface.

A distinct advantage over the prior art can be identified by considering the impact absorption of multiple smaller impacts in amongst larger impacts. A typical impact-absorbing helmet is configured to dissipate the impacts of a single large event, for example the impact of a user’s head on a floor after falling from a height. The present invention considers not only single large impacts, but multiple smaller and larger impacts and the dissipation of the energy of these impacts via both rotational deformation and linear (compressive) deformation. For example, if a user, equipped with a helmet containing an impact-absorbing structure according to the present invention, were to fall and their helmet impact a number of objects / surfaces during the fall, the helmet would be capable of dissipating energy from those impacts without sacrificing the ability to dissipate energy from the large impact of hitting the floor, because of the aforementioned technical benefits. Such a situation may arise for example whilst on horseback.

The impact-absorbing layer according to the invention is capable of dissipating small impacts via deformation of the tips (i.e. narrow end) of the elongate members, which are more susceptible to deformation by virtue of their small cross- section. This is in contrast to the extant solutions in the art, which are configured to give way under heavy impacts.

When compared to extant solutions of a helmet ‘liner’, it is readily apparent that the maximum rotation of the helmet with respect to the user’s head has a maximum limit that is reached ‘abruptly’ when the liner reaches a retaining structure. The abruptness of the rotation maximum translates to a secondary ‘shock’ that can be delivered to the user as the helmet ceases rotating and the rotational energy is suddenly transmitted to the user’s head. This is a result of not only the implementation of the rotation limiting factor, but also of the manner in which rotational energy is dissipated by the ‘liner’ solution.

In the liner-based solution, the rotational energy is dissipated by the frictional forces between the helmet and the liner. As such, the energy dissipation is at a maximum once the helmet begins its rotation about the user’s head. It is further an object of the liner approach merely to rotate the helmet such that the incident force is no longer inducing a rotation, rather than to dissipate the rotational energy per se.

In contrast, the solution of the present application dissipates rotational energy by deformation of the elongate members of the impact-absorbing structure, and further does so in a manner that has no ‘abrupt’ element. The compressibility, and extensibility, of the foam used for construction of the impact-absorbing structure has the benefit of introducing a gradually increasing resistance to rotation of the outer surface to the inner shell. Thus an abrupt ‘shock’ to the user’s head is avoided.

In a preferred embodiment, the elongate tapering members are oriented such that the widest point of the elongate members are base portions and are affixed to the outer surface, and the top portions abut, but are not secured to, the inner shell. Such an orientation provides a synergistic benefit coupled with the shape of the elongate members, in that relative rotation of the outer surface to the inner shell produces a greater torque at the top end of the elongate member, which is closer to the user’s head. The body of the elongate member closer to the top end of the elongate member is more readily deformed by relative rotation of the inner shell and outer surface by dint of its narrowed shape. As a result, a ‘stiffer’ or more resilient foam may be used in the construction of the elongate member without compromising the ability of the impact-absorbing structure to dissipate rotational energy. This may be advantageous in providing a helmet that has more resilience to ‘compressive’ forces. It is a further benefit of this configuration that the mass of the elongate member is distributed further from the inner shell, thus increasing the energy required to induce rotation of the outer surface and further reducing energy transmitted from an impact inducing a rotation of the outer surface to the inner shell.

In some embodiments, as demonstrated in Fig. 7A, a further outer surface 21 A is provided which is supported by the outer surface 21 by a further impact absorbing layer 70. Impact absorbing layer 70 may be formed from similar materials to the elongate member, whilst appreciating that the materials for the further impact absorbing layer 70 and the elongate member 10 may not be the same material in a given embodiment. In some embodiments, the further impact absorbing layer is formed from a resiliently and/or reversibly deformable material. In some embodiments, further impact absorbing layer is formed from a closed cell or open cell foam. In some embodiments, the further impact absorbing layer is formed from flexible plastic.

Further outer surface 21 A may be formed of a similar or substantially the same material as outer surface 21.

In some embodiments, as depicted in Fig. 7B, a supplementary impact absorbing layer 71 is retained between the inner shell 20 and a supplementary inner shell 20A. in some embodiments, the supplementary impact layer is formed from similar materials to the elongate member 10, whilst it should be appreciated that the supplementary impact absorbing layer 20A and the elongate member 10 may not be the same material as one another in a given embodiment. In some embodiments, the supplementary impact absorbing layer 20A is formed from a resiliently and/or reversibly deformable material. In some embodiments, the supplementary impact absorbing layer is formed from a closed cell or open cell foam. In some embodiments, the supplementary impact absorbing layer is formed from flexible plastic.

Supplementary inner shell 20A may be formed of a similar or substantially the same material as inner shell 20.

As shown in Fig. 7B, some embodiments may comprise both a further impact absorbing layer and a supplementary impact absorbing layer. Flowever, in some embodiments there may only be provided a supplementary impact absorbing layer and not a further impact absorbing layer.

In some embodiments, the impact-absorbing structure may be configured to be affixed to other structures of a human, or animal body.

Although some of the figures depict an exemplary embodiment wherein the invention is included in a helmet, the arrangement of the impact-absorbing layer in these figures may be equally effective in other arrangements for protection of other body parts i.e. knees, elbows, or for inanimate objects.

The invention as described herein is not limited to use in helmets or indeed personal protective equipment, but could find use for the protection of inanimate objects, equipment and devices, for example for storage and transportation of goods and articles. The layered structure in the figured and relating to the invention would then form part of a protective layered structure, for example within packaging. All references made herein to orientation (e.g. top, bottom, etc.) are made for the purposes of describing relative spatial arrangements of features, and are not intended to be limiting in any sense.

The scope of the present disclosure includes any novel feature or combination of features disclosed therein either explicitly or implicitly or any generalisation thereof irrespective of whether or not it relates to the claimed invention or mitigate against any or all of the problems addressed by the present invention. The applicant hereby gives notice that new claims may be formulated to such features during prosecution of this application or of any such further application derived therefrom. In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims and features from respective independent claims may be combined in any appropriate manner and not merely in specific combinations enumerated in the claims.

Claims

1. A protective helmet impact-absorbing structure, comprising: at least one elongate tapering member formed unitarily from foam, comprising: a base portion; a top portion; and at least one side portion extending in a tapering manner therebetween; wherein the at least one elongate tapering member is arranged for operative location between an inner shell and an outer surface of the helmet.

2. An impact absorbing structure according to claim 1 , further comprising an inner shell.

3. An impact absorbing structure according to claim 1 or 2, further comprising an outer surface.

4. An impact absorbing structure according to claim 2 or 3, wherein the at least one elongate tapering member is affixed to the inner shell at the base portion.

5. An impact absorbing structure according to claim 2 or 3, wherein the at least one elongate tapering member is affixed to the inner shell at the top portion.

6. An impact absorbing structure according to any of claims 3 -4, wherein the at least one elongate tapering member is affixed to the outer surface at the top portion.

7. An impact absorbing structure according to any of claims 1 -3 and or 5, wherein the at least one elongate tapering member is affixed to the outer surface at the base portion.

8. An impact absorbing structure according to claim 5 or 6, wherein the top portion is the narrowest point of the elongate tapering member.

9. An impact absorbing structure according to any preceding claim, wherein the base portion of the at least one elongate tapering member comprises a recess.

10. An impact absorbing structure according to claim 9, wherein the recess comprises a blind bore in the centre of the base portion.

11. An impact absorbing structure according to any preceding claim, wherein the at least one elongate tapering member is formed from a memory foam.

12. An impact absorbing structure according to claim 11 , wherein the memory foam has a slow springback rate.

13. An impact absorbing structure according to any preceding claim, wherein the at least one elongate tapering member is generally frusto-conical in shape.

14. An impact absorbing structure according to any of claims 1 -12, wherein the at least one elongate tapering member is generally pyramidal in shape.

15. An impact absorbing structure according to any preceding claim, comprising at least two elongate tapering members.

16. An impact absorbing structure according to claims 15, wherein at least one elongate tapering member with a generally frusto-conical shape is included, and at least one elongate tapering member with a generally pyramidal shape is included.

17. An impact absorbing structure according to claims 15 or 16 wherein a spacing between the elongate members is uniform.

18. An impact absorbing structure according to claims 15 or 16 wherein a spacing between the elongate members is varied to increase or decrease local resistance to deformation of the elongate members in response to an incident force.

19. An impact absorbing structure according to any of claims 2-18 wherein the inner shell is formed of a rigid or semirigid material.

20. An impact absorbing structure according to any of claims 3-19 wherein the outer surface is formed of a rigid or semirigid material.

21. An impact absorbing structure according to any of claims 3-20 further comprising a further impact absorbing layer disposed radially outward from the outer surface, and a further outer surface disposed radially outward therefrom.

22. An impact absorbing structure according to any of claims 2-21 further comprising a supplementary impact absorbing layer disposed radially inward from the inner shell, and a supplementary inner shell disposed radially inward therefrom.

23. A helmet for a user, comprising an impact-absorbing structure according to any preceding claim.