CN117677316A

CN117677316A - Headgear and device for headgear

Info

Publication number: CN117677316A
Application number: CN202280024169.3A
Authority: CN
Inventors: P·哈尔丁; 李晓盖
Original assignee: Mips AB
Current assignee: Mips AB
Priority date: 2021-03-24
Filing date: 2022-03-22
Publication date: 2024-03-08
Also published as: CA3213405A1; WO2022200336A1; GB202104112D0; EP4312643A1

Abstract

A cap (40) for use with a protective headgear, comprising: a hard shell (41) forming a layer covering the inner surface area defined by the cap (40) and formed by one or more sections; an adjustment mechanism (50) configured to adjust the shape of the rigid housing (41) to conform to the individual wearer's head in a first mode of operation and to secure the shape of the housing (41) in a second mode of operation; and wherein the cap (40) is configured such that the rigid housing (41) substantially maintains a fixed shape during normal use and when subjected to forces applied to the cap during impact.

Description

Headgear and device for headgear

Technical Field

The present invention relates to a device for protecting a headgear and a protective headgear comprising said device.

Background

Impact protection devices are generally intended to reduce the energy transferred by an impact to an object, such as a person to be protected. This may be achieved by an energy absorbing device, an energy redirecting device, or a combination thereof. The energy absorbing device may include an energy absorbing material, such as a foam material, or a structure configured to elastically and/or plastically deform in response to an impact. The energy redirecting device can include a structure configured to slide, shear, or otherwise move in response to an impact.

The impact protection apparatus comprises a protective garment for protecting a wearer of the garment. It is known that protective garments include energy absorbing means and/or energy redirecting means. For example, such devices are widely used in protective headgear such as helmets.

Examples of helmets that include an energy absorbing device and an energy redirecting device include WO 2001/045526 and WO 2011/139224 (the entire contents of which are incorporated herein by reference). In particular, these helmets comprise at least one layer formed of an energy absorbing material and at least one layer that is capable of moving relative to the helmet's wearer's head under impact.

The helmet construction is generally the same whether intended for wearing by adults or children. However, there are differences between adults and children of different ages, which may affect the impact effect.

In particular, the skull of children around the age of 3 years old or less has not healed completely, but remains separated. The separated region is called the suture. The presence of a baby's skull suture results in different manifestations of the skull upon head impact. This can be simulated by using, among other things, a finite element model of the child's skull. Fig. 9 schematically shows the development of the skull and closure of the bone suture from a neonate to a 3 year old child.

Simulations were performed using a validated children head Finite Element (FE) model. The model consisted of a skull, brain, membrane and cerebrospinal fluid and a validated helmet FE model. FE simulation mimics the fall of the head and helmet, similar to the test method used in the european test standard (EN 1078) for current children's bike helmets. The helmet and head fall off at a speed of 5.4m/s, striking the top of the helmet.

Fig. 10 shows a heat map of the skull of 1.5 years and 18 years, illustrating the skull stress caused by the impact. It can be seen that the stress in the skull of children 18 months old is greater compared to 18 years old (adults). Stress is concentrated around the suture. This indicates that children are more prone to skull fracture and other severe injuries due to the suture.

It is an object of the present invention to at least partially solve some of the problems discussed above.

Disclosure of Invention

According to a first aspect of the present invention there is provided a cap for use with a protective headgear, comprising: a hard shell forming a layer covering an inner surface area defined by the cap and formed by one or more sections; an adjustment mechanism configured to adjust a shape of the rigid shell to conform to an individual wearer's head in a first mode of operation and configured to secure the shape of the shell in a second mode of operation; and wherein the cap is configured such that the rigid housing substantially maintains a fixed shape during normal use and when subjected to forces applied to the cap during impact.

Optionally, the rigid shell forms an inner surface of the cap, the inner surface being arranged to face towards the wearer's head in normal use, and the rigid shell is configured to directly contact the wearer's head.

Optionally, in normal use, the cap is free of compressible material more inward than the rigid shell relative to the wearer's head.

Optionally, the adjustment mechanism is configured to be able to adjust the shape of the hard shell such that the average gap size between the hard shell and the standard head form is not greater than 2mm at a circumferential portion of the hard shell or over the entire hard shell. Optionally, the adjustment mechanism is configured to be able to adjust the shape of the rigid housing such that the average gap size is no greater than 1mm.

Optionally, the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during an impact the average gap size between the hard shell and the standard head form increases by no more than 2mm at a circumferential portion of the hard shell or over the whole hard shell. Optionally, the average gap size increases by no more than 1.5mm during impact.

Optionally, the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during an impact, the average displacement between the opposing surfaces of the hard shell facing the standard head form is no more than 2mm over a circumferential portion of the hard shell or over the entire hard shell. Alternatively, the average displacement increases by no more than 1.5mm during impact.

Optionally, the adjustment mechanism is configured to be able to adjust the shape of the hard shell such that the maximum gap size between the hard shell and the standard head form is not more than 2mm at a circumferential portion of the hard shell or over the entire hard shell. Optionally, the adjustment mechanism is configured to be able to adjust the shape of the rigid housing such that the maximum gap size is no greater than 1mm.

Optionally, the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during an impact the maximum gap size between the hard shell and the standard head form increases by no more than 2mm at a circumferential portion of the hard shell or over the whole hard shell. Optionally, the maximum gap size increases by no more than 1.5mm during impact.

Optionally, the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during an impact, the maximum displacement between the opposing surfaces of the hard shell facing the wearer's head is no more than 2mm at a circumferential portion of the hard shell or over the entire hard shell. Optionally, the maximum displacement increases by no more than 1.5mm during impact.

Optionally, the material forming the region of the rigid shell has a young's modulus of at least 1 GPa.

Optionally, the section forming the rigid housing is formed of polycarbonate.

Optionally, the rigid shell is at least 1mm thick.

Optionally, in normal use, the surface of the cap that is arranged to face away from the wearer's head is a low friction surface. Optionally, the low friction surface is provided by material properties forming one or more sections of the hard shell.

Optionally, in normal use, the rigid housing is arranged to cover at least a portion of the forehead, the top of the head, a portion of the rear brain scoop and a portion of both sides of the head of the wearer.

According to a second aspect of the present invention there is provided a protective headgear comprising: the cap of any preceding claim; and at least one protective layer covering the cap.

Optionally, the cap is configured to rotate relative to the at least one protective layer under an oblique impact to the protective layer.

Optionally, the headgear further comprises at least one connector configured to connect the cap and the at least one protective layer while allowing relative rotation.

Optionally, a sliding interface is provided between the cap and the at least one protective layer.

Optionally, a shear interface is provided between the cap and the at least one protective layer.

Optionally, the at least one protective layer comprises an energy absorbing layer.

Optionally, the at least one protective layer comprises a hard outer hard shell.

According to a third aspect of the present invention there is provided a method of protecting a wearer of a headgear from head injury comprising: wrapping a wearer's head in a cap, the cap comprising: a hard shell forming a layer covering an inner surface area defined by the cap and formed by one or more sections; an adjustment mechanism for adjusting the shape of the hard shell in a first mode of operation and configured to fix the shape of the hard shell in a second mode of operation; and wherein the cap is configured such that the rigid shell substantially maintains a fixed shape when subjected to forces applied to the cap during normal use and during impact; the method includes adjusting the shape of the rigid shell to conform to the wearer's head and securing the shape.

Optionally, the shape of the rigid shell is adjusted such that in normal use the average gap size between the rigid shell and the wearer's head is not more than 2mm. Optionally, the shape of the rigid shell is adjusted such that the average gap size is not greater than 1mm.

Drawings

The invention is described in detail below with reference to the attached drawing figures, wherein:

Fig. 1 schematically shows a cross-section through a first example helmet;

fig. 2 schematically shows a cross-section through a second example helmet;

fig. 3 schematically shows a cross-section through a third example helmet;

fig. 4 schematically shows a cross-section through a fourth example helmet;

fig. 5 schematically shows a cross-section through a fifth example helmet;

fig. 6 schematically shows a cross-section through a sixth example helmet;

fig. 7 schematically shows a cross-section through a seventh example helmet;

fig. 8 shows an eighth example helmet;

FIG. 9 schematically illustrates the development of the skull and closure of the bone suture from a neonate to a 3 year old child;

FIG. 10 shows a heat map of the skull of 1.5 years old and 18 years old, illustrating the skull stress caused by the impact;

FIG. 11 shows a first example cap in a first configuration;

FIG. 12 shows the first example cap in a second configuration;

FIG. 13 shows a second example cap in a first configuration;

FIG. 14 shows a third example cap in a first configuration;

FIG. 15 shows a fourth example cap in a first configuration;

fig. 16 shows the gap between the cap and the head form.

Detailed Description

It should be noted that the figures are schematic, the thickness of the various layers depicted in the figures and/or the proportion of any gaps between the layers are exaggerated for clarity, and may of course be adjusted as needed and desired.

The general features of an example helmet are described below with reference to fig. 1-7.

Fig. 1 to 7 show an example helmet 1 comprising an energy absorbing layer 3. The purpose of the energy absorbing layer 3 is to absorb and dissipate energy from the impact to reduce the energy transferred to the wearer of the helmet. Within the helmet 1, the energy absorbing layer may be the primary energy absorbing element. Although other elements of the helmet 1 may absorb this energy to a more limited extent, this is not their primary purpose.

The energy absorbing layer 3 may absorb energy from the radial component of the impact more effectively than from the tangential component of the impact. The term "radial" generally refers to a direction substantially toward the center of the wearer's head, e.g., substantially perpendicular to the outer surface of the helmet 1. The term "tangential" may refer to a direction substantially perpendicular to the radial direction in a plane comprising the radial direction and the impact direction.

The energy absorbing layer may be formed of an energy absorbing material such as a foam material. Preferred such materials include Expanded Polystyrene (EPS), expanded polypropylene (EPP), expanded Polyurethane (EPU), vinyl nitrile foam; or strain rate sensitive foams, e.g. in Poron ^TM And D3O ^TM Those sold by brand name.

Alternatively or additionally, the energy absorbing layer may have a structure that provides energy absorbing properties. For example, the energy absorbing layer may include deformable elements, such as cells or finger-like protrusions, that deform upon impact to absorb and dissipate the energy of the impact.

As shown in fig. 6, the energy absorbing layer 3 of the helmet 1 is divided into an outer portion 3A and an inner portion 3B.

The energy absorbing layer is not limited to one particular arrangement or material. The energy absorbing layer 3 may be provided by a plurality of layers having different arrangements, i.e. being formed of different materials or having different structures. The energy absorbing layer 3 may be a relatively thick layer. For example, it may be the thickest layer of the helmet 1.

Fig. 1 to 7 show an example helmet 1 comprising an outer layer 2. The purpose of the outer layer 2 may be to provide rigidity to the helmet. This may help to spread the impact energy over a larger area of the helmet 1. The outer layer 2 may also provide protection against objects that may puncture the helmet 1. Thus, the outer shell may be a relatively strong and/or rigid layer, for example compared to the energy absorbing layer 3. The outer layer 2 may be a relatively thin layer, for example compared to the energy absorbing layer 3.

The outer layer 2 may be formed of a relatively strong and/or rigid material. Preferred such materials include polymeric materials such as, for example, polycarbonate (PC), polyvinyl chloride (PVC), or Acrylonitrile Butadiene Styrene (ABS). Advantageously, the polymeric material may be fibre reinforced using materials such as fiberglass, aramid, twaron, carbon fibre and/or Kevlar.

As shown in fig. 7, one or more outer panels 7 may be mounted to the outer layer 2 of the helmet 1. The outer panel 7 may be formed from a relatively strong and/or rigid material, for example from the same type of material from which the outer layer 2 may be formed. The choice of material for forming the outer panel 7 may be the same as or different from the material for forming the outer layer 2.

In some example helmets, the outer layer 2 and/or the energy absorbing layer 3 can be adjustable in size to provide a custom fit. For example, the outer layer 2 may be provided in separate front and rear portions. The relative positions of the front and rear portions can be adjusted to vary the size of the outer layer 2. To avoid gaps in the outer layer 2, the front and rear portions may overlap. The energy absorbing layer 3 may also be provided in separate front and rear portions. These may be arranged such that the relative positions of the front and rear portions may be adjusted to change the size of the energy absorbing layer 3. To avoid gaps in the energy absorbing layer 3, the front and rear portions may overlap.

Fig. 1-4 show an example helmet 1 that includes an interface layer 4. Although not shown in fig. 5-7, these example helmets may also include an interface layer 4. The purpose of the interface layer 4 may be to provide an interface between the helmet and the wearer. In some arrangements, this may improve the comfort of the wearer. The interface layer 4 may be arranged to place the helmet on the wearer's head. The interface layer 4 may be provided as a single part or as a plurality of sections.

The interface layer 4 may be configured to at least partially conform to the wearer's head. For example, the interface layer 4 may be elastic and/or may include an adjustment mechanism for adjusting the size of the interface layer 4. In one arrangement, the interface layer may engage the top of the wearer's head. Alternatively or additionally, the interface layer 4 may comprise an adjustable section configured to surround the wearer's head.

The interface layer 4 may include a comfort pad 4A. Multiple sections of comfort pad 4A may be provided. A comfort pad 4A may be provided on the base plate 4B for mounting the comfort pad to the remainder of the helmet 1.

The purpose of the comfort pad 4A is to improve the comfort of wearing the helmet and/or to provide a better fit. The comfort pad may be formed of a relatively soft material, for example, as compared to the energy absorbing layer 3 and/or the outer layer 2. The comfort pad 4A may be formed of a foam material. However, the foam material may have a lower density and/or be thinner than the foam material used for the energy absorbing layer 3. Thus, the comfort pad 4A will not absorb a significant amount of energy during an impact, i.e., to reduce injury to the helmet wearer. Comfort pads are recognized in the art as being different from energy absorbing layers, even though they may be constructed of some similar material.

The interface layer 4 and/or the comfort pad 4A, which may be a part thereof, may be removable. This may enable the interface layer 4 and/or the comfort pad 4A to be cleaned and/or may enable the interface layer and/or the comfort pad 4A to be provided configured to suit a particular wearer.

Straps, such as chin straps, may be provided to secure the helmet 1 to the wearer's head.

The helmet of fig. 1-4 is configured such that the interface layer 4 is able to move, e.g. slide, in a tangential direction with respect to the energy absorbing layer 3 in response to an impact. As shown in fig. 1 to 4, the helmet may further comprise a connector 5 between the energy absorbing layer 3 and the interface layer 4, which allows for relative movement between the energy absorbing layer 3 and the interface layer 4, while connecting the elements of the helmet together.

The helmet of fig. 5 is configured such that the outer layer 2 is able to move, e.g. slide, in a tangential direction relative to the energy absorbing layer 3 in response to an impact. As shown in fig. 5, the helmet 1 may further comprise a connector 5 between the energy-absorbing layer 3 and the outer layer 2, which allows for relative movement between the energy-absorbing layer 3 and the outer layer 2, while connecting the elements of the helmet together.

The helmet of fig. 6 is configured such that the outer portion 3A of the energy absorbing layer 3 is movable, e.g. slidable, in a tangential direction with respect to the inner portion 3B of the energy absorbing layer 3 in response to an impact. As shown in fig. 6, the helmet 1 may further comprise a connector 5 between the outer portion 3A of the energy-absorbing layer 3 and the inner portion 3B of the energy-absorbing layer 3, which allows relative movement between the outer portion 3A of the energy-absorbing layer 3 and the inner portion 3B of the energy-absorbing layer 3, while connecting the elements of the helmet together.

The helmet of fig. 7 is configured such that the outer plate 8 is able to move, e.g. slide, in tangential direction with respect to the outer layer 2 in response to an impact. As shown in fig. 7, the helmet may also include a connector 5 between the outer panel 8 and the outer layer 2 that allows relative movement between the outer panel 7 and the outer layer 2 while connecting the elements of the helmet together.

The purpose of the helmet layers moving or sliding relative to each other may be to redirect impact energy that would otherwise be transferred to the wearer's head. This may improve protection of the wearer against the tangential component of the impact energy. The tangential component of the impact energy typically results in rotational acceleration of the wearer's head. It is well known that such rotation can lead to brain damage. Helmets having layers that move relative to each other have been shown to reduce rotational acceleration of the wearer's head. A typical decrease may be about 25%, but in some cases the decrease may be as high as 90%.

Preferably, the relative movement between the helmet layers results in a total offset between the outermost helmet layer and the innermost helmet layer of at least 0.5cm, more preferably at least 1cm, still more preferably at least 1.5cm. Preferably, the relative movement may occur in any direction, for example in a circumferential direction around the helmet, from left to right, from front to back and any direction therebetween.

Regardless of how the helmet layers are configured to move relative to each other, it is preferred that the relative movement, e.g., sliding, can occur under the force of a typical impact for which the helmet is designed (e.g., an impact that the wearer is expected to survive). This force is significantly higher than the helmet may be subjected to during normal use. The impact forces tend to compress the layers of the helmet together, thereby increasing the reaction forces between the components and thus the friction. In the case of helmets configured with layers that slide relative to each other, the interface between them may need to be configured to slide even under the high reaction forces experienced between them under impact.

As shown in fig. 1 to 7, a sliding interface may be provided between the layers of the helmet 1, the layers being configured to slide relative to each other. At the sliding interface, the surfaces slide relative to each other to achieve a relative sliding between the layers of the helmet 1. The sliding interface may be a low friction interface. Thus, friction reducing means may be provided at the sliding interface. An example sliding interface will be further described below for each example helmet 1 shown in fig. 1-7.

The friction reducing means may be a low friction material or a lubricating material. For example, these may be provided as a continuous layer, or as more discrete patches, or portions of material. Possible low friction materials for friction reducing devices include waxy polymers such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE, teflon ^TM Such as Tamarack ^TM A nonwoven, such as felt. Such low friction materials may have a thickness of about 0.1-5mm, although other thicknesses may be used, depending on the material selected and the properties desired. Possible lubricating materials include oils, polymers, microspheres or powders. Can be used forA combination of the above is used.

In one example, the low friction material or lubricating material may be a polysiloxane-containing material. In particular, the material may include (i) an organic polymer, a polysiloxane, and a surfactant; (i) Organic polymers and copolymers based on polysiloxanes and organic polymers; or (iii) a non-elastomeric crosslinked polymer obtained or obtainable by crosslinking a polysiloxane and an organic polymer. A preferred choice of such materials is described in WO 2017148958.

In one example, the low friction material or lubricating material may comprise a mixture of (i) an olefin polymer, (ii) a lubricant, and optionally one or more other agents. A preferred choice of such materials is described in WO 2020115063.

In one example, the low friction material or lubricating material may include a density of 960kg/m or less ³ An Ultra High Molecular Weight (UHMW) polymer, preferably an olefin polymer. A preferred choice of such materials is described in WO 2020115063.

In one example, the low friction material or lubricating material may include polyketone. Preferred choices of such materials are described in WO 2020/260185.

In some arrangements, it may be desirable to configure the low friction interface such that the static and/or dynamic coefficient of friction between the materials forming the sliding surface at the sliding interface is between 0.001 and 0.3 and/or below 0.15. The coefficient of friction may be tested in a standard manner, such as standard test method ASTM D1894.

The friction reducing means may be provided on an integral part of one or both of the layers of the helmet 1, which layers are configured to slide relative to each other, or on an integral part of one or both of the layers of the helmet 1. In some examples, the helmet layer may have a dual function, including serving as a friction reducing device. Alternatively or additionally, the friction reducing means may be separate from, but arranged between, the layers of the helmet 1 that are configured to slide relative to each other.

Instead of a sliding interface, in some examples, a shear interface may be provided between layers of the helmet 1 that are configured to move relative to each other. At the shear interface, the shear layer shears to effect relative movement between the layers of the helmet 1. The shear layer may comprise a gel or liquid, which may be held within a flexible jacket. Alternatively, the shear layer may comprise two opposing layers connected by a deformable element that deforms to enable shearing between the two opposing layers.

A single shear layer may be provided which substantially fills the volume between the two layers of the helmet. Alternatively, one or more shear layers may be provided which fill only a portion of the volume between the two layers of the helmet, e.g. leaving considerable space around the shear layers. The space may include a sliding interface, as described above. Thus, the helmet may have a combination of a shear interface and a sliding interface. Such a shear layer may be used as the connector 5, as will be further described below.

Fig. 1 to 7 schematically show a connector 5. The connector 5 is configured to connect two layers of the helmet while enabling relative movement, such as sliding or shearing, between the layers. A different number of connectors 5 than shown in fig. 1 to 7 may be provided. The connector 5 may be located in a different position than shown in figures 1 to 7, for example at the peripheral edge of the helmet 1, rather than in the central portion.

Typically, the connector 5 comprises a first and a second attachment portion configured to be attached to the first and second portion of the helmet, respectively, and a deformable portion between the first and second attachment portions that enables the first and second attachment portions to move relative to each other to enable movement between the first and second portions of the helmet. The connector 5 may absorb some of the impact energy by deforming.

The specific arrangement of each example helmet shown in fig. 1-7 is as follows.

Fig. 1 shows a helmet comprising an outer layer 2, an energy absorbing layer 3 and an interface layer 4. The interface layer 4 is provided as a single layer and comprises a comfort pad.

The helmet of fig. 1 is configured such that the interface layer 4 is able to slide relative to the energy absorbing layer 3 in response to an impact. A sliding interface is provided between the interface layer 4 and the energy absorbing layer 3.

A sliding layer 7 is provided on the surface of the energy absorbing layer 3 facing the sliding interface. The sliding layer 7 may be molded to the energy absorbing layer 3 or otherwise attached to the energy absorbing layer. The sliding layer 7 may be formed of a relatively hard material, for example with respect to the energy absorbing layer 3. The sliding layer 7 is configured to provide friction reducing means to reduce friction at the sliding interface. This can be achieved by forming the sliding layer 7 from low friction materials such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE. Alternatively or additionally, this may be achieved by applying a low friction coating to the sliding layer 7 and/or applying a lubricant to the sliding layer 7.

Alternatively or additionally, friction reducing means may be provided by forming the energy absorbing layer 3 from a low friction material, by applying a low friction coating to the energy absorbing layer 3 and/or by applying a lubricant to the energy absorbing layer 3 to reduce friction at the sliding interface.

The helmet 1 shown in fig. 1 further comprises a connector 5 attached to the interface layer 4. The connector is also connected to the sliding layer 7 to allow relative sliding between the energy absorbing layer 3 and the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, such as the energy absorbing layer 3 or the outer shell 2. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

It should be appreciated that this arrangement of energy absorbing layer 3 and interface layer 4 may be added to any of the helmets described herein.

Fig. 2 shows a helmet comprising an outer layer 2, an energy absorbing layer 3 and an interface layer 4. The interface layer 4 is provided as a plurality of separate sections, each of which comprises a comfort pad.

The helmet of fig. 2 is configured such that the sections of the interface layer 4 are able to slide relative to the energy absorbing layer 3 in response to an impact. A sliding interface is provided between the region of the interface layer 4 and the energy absorbing layer 3.

The helmet 1 shown in fig. 2 further comprises a connector 5 attached to each individual section of the interface layer 4. The connector 5 is also attached to the sliding layer 7 to allow relative sliding between the energy absorbing layer 3 and the region of the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, such as the energy absorbing layer 3 or the outer shell 2. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

Fig. 3 shows a helmet comprising an outer layer 2, an energy absorbing layer 3 and an interface layer 4. The interface layer 4 is provided as a single layer and comprises a comfort pad 4A attached to a substrate 4B. The base plate 4B may be bonded to the outside of the comfort pad 4A. Such bonding may be by any means, for example by adhesive or by high frequency welding or stitching.

The helmet of fig. 3 is configured such that the interface layer 4 is able to slide relative to the energy absorbing layer 3 in response to an impact. A sliding interface is provided between the interface layer 4 and the energy absorbing layer 3.

The substrate 4B of the interface layer 4 faces the sliding interface. The substrate 4B may be formed of a relatively hard material, for example, with respect to the energy absorbing layer 3 and/or the comfort pad 4A. The base plate 4B is configured to provide friction reducing means to reduce friction at the sliding interface. This may be achieved by forming the base plate 4B from low friction materials such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE. Alternatively or additionally, this may be achieved by applying a low friction coating to the substrate 4B and/or applying a lubricant to the substrate 4B. In an alternative example, the substrate 4B may be formed of a fabric material, optionally coated with a low friction material.

The helmet 1 shown in fig. 3 further comprises a connector 5 attached to the interface layer 4. The connector is also connected to the energy absorbing layer to allow relative sliding between the energy absorbing layer 3 and the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, such as the outer shell 2. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1

Fig. 4 shows a helmet comprising an outer layer 2, an energy absorbing layer 3 and an interface layer 4. The interface layer 4 is provided as a plurality of separate sections, each comprising a comfort pad 4A attached to a substrate 4B. The base plate 4B may be bonded to the outside of the comfort pad 4A. Such bonding may be by any means, for example by adhesive or by high frequency welding or stitching.

The helmet of fig. 4 is configured such that the interface layer 4 is able to slide relative to the energy absorbing layer 3 in response to an impact. A sliding interface is provided between the interface layer 4 and the energy absorbing layer 3.

The substrate 4B of the region of the interface layer 4 faces the sliding interface. The substrate 4B may be formed of a relatively hard material, for example, with respect to the energy absorbing layer 3 and/or the comfort pad 4A. The base plate 4B is configured to provide friction reducing means to reduce friction at the sliding interface. This may be achieved by forming the base plate 4B from low friction materials such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE. Alternatively or additionally, this may be achieved by applying a low friction coating to the substrate 4B and/or applying a lubricant to the substrate 4B. In an alternative example, the substrate 4B may be formed of a fabric material, optionally coated with a low friction material.

The helmet 1 shown in fig. 4 also comprises a connector 5 attached to the region of the interface layer 4. The connector 5 is also connected to the energy absorbing layer 3 to allow relative sliding between the energy absorbing layer 3 and the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, such as the outer shell 2. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

Fig. 5 shows a helmet comprising an outer layer 2 and an energy absorbing layer 3. Although not shown, an interface layer may be additionally provided.

The helmet of fig. 5 is configured such that the outer layer 2 is able to slide relative to the energy absorbing layer 3 in response to an impact. A sliding interface may be provided between the outer layer 2 and the energy absorbing layer 3.

Although not shown, an additional layer may be provided on the surface of the energy absorbing layer 3 facing the sliding interface. The additional layer may be molded to the energy absorbing layer 3 or otherwise attached to the energy absorbing layer. The additional layer may be formed of a relatively hard material, for example with respect to the energy absorbing layer 3. The additional layer may be configured to provide friction reducing means to reduce friction at the sliding interface. This may be achieved by forming the additional layer from a low friction material such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE. Alternatively or additionally, this may be achieved by applying a low friction coating to the additional layer and/or applying a lubricant to the additional layer.

Alternatively or additionally, friction reducing means may be provided by forming the outer layer 2 from a low friction material, providing an additional low friction layer on the surface of the outer layer 2 facing the sliding interface, by applying a low friction coating to the outer layer 2 and/or by applying a lubricant into the outer layer 2 to reduce friction at the sliding interface.

The helmet 1 shown in fig. 5 further comprises a connector 5 attached to the outer layer 2. The connector 5 is also attached to the energy absorbing layer 3 (or an additional layer) to allow relative sliding between the sections of the energy absorbing layer 3 and the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, for example an interface layer. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

It should be appreciated that this arrangement of the outer shell 2 and the energy absorbing layer 3 may be added to any of the helmets described herein.

Fig. 6 shows a helmet comprising an outer layer 2 and an energy absorbing layer 3. As shown, the energy absorbing layer 3 of the helmet shown in fig. 6 is divided into an outer portion 3A and an inner portion 3B. Although not shown, an interface layer may be additionally provided.

The helmet of fig. 6 is configured such that the outer portion 3A of the energy absorbing layer 3 is able to slide relative to the inner portion 3B of the energy absorbing layer 3 in response to an impact. The sliding interface may be provided between the outer portion 3A of the energy absorbing layer 3 and the inner portion 3B of the energy absorbing layer 3.

Although not shown, an additional layer may be provided on the surface of one or both of the inner portion 3A and the outer portion 3B of the energy absorbing layer 3 facing the sliding interface. Additional layers may be molded to or otherwise attached to the inner or outer portions 3A, 3B of the energy absorbing layer 3. The additional layer may be formed of a relatively hard material, for example with respect to the energy absorbing layer 3. The additional layer may be configured to provide friction reducing means to reduce friction at the sliding interface. This may be achieved by forming the additional layer from a low friction material such as PC, PTFE, ABS, PVC, nylon, PFA, EEP, PE and UHMWPE. Alternatively, or additionally, this may be achieved by applying a low friction coating to the additional layer and/or applying a lubricant to the additional layer.

Alternatively or additionally, friction reducing means may be provided by forming one or both of the inner and outer portions 3A, 3B of the energy absorbing layer 3 from a low friction material, by providing an additional low friction layer on the surfaces of the inner and outer portions 3A, 3B of the energy absorbing layer 3 facing the sliding interface, by applying a low friction coating to the inner and outer portions 3A, 3B of the energy absorbing layer 3 and/or by applying a lubricant to the inner and outer portions 3A, 3B of the energy absorbing layer 3 to reduce friction at the sliding interface.

The helmet 1 shown in fig. 6 also comprises a connector 5 attached to the outer layer 2. The connector 5 is also attached to the energy absorbing layer 3 (or an additional layer) to allow relative sliding between the sections of the energy absorbing layer 3 and the interface layer 4. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, for example an interface layer. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

It should be appreciated that this arrangement of the inner and outer portions 3A, 3B of the energy absorbing layer 3 may be added to any of the helmets described herein.

Fig. 7 shows a helmet comprising an outer layer 2 and an energy absorbing layer 3. As shown in fig. 7, one or more outer panels 7 are mounted to the outer layer 2 of the helmet 1. The outer panel 7 may be formed from a relatively strong and/or rigid material, for example from the same type of material from which the outer layer 2 may be formed. Although not shown, an interface layer may be additionally provided.

The helmet in fig. 7 is configured such that the outer panel 8 is able to slide relative to the outer layer 2 in response to an impact. A sliding interface may be provided between the outer panel 8 and the outer layer 2.

Friction reducing means may be provided by forming the outer layer 2 and/or the outer plate 8 from a low friction material, by providing an additional low friction layer on the surface of the outer layer 2 and/or the outer plate 8 facing the sliding interface, by applying a low friction coating to the outer layer 2 and/or the outer plate 8, and/or by applying a lubricant to the outer layer 2 and/or the outer plate 8 to reduce friction at the sliding interface.

The helmet 1 shown in fig. 7 further comprises a connector 5 attached to the outer plate 7. The connector 5 is also attached to the outer layer 2 to allow relative sliding between the plate 7 and the outer layer 2. Alternatively or additionally, one or more connectors 5 may be connected to another part of the rest of the helmet 1, such as the energy absorbing layer 3. The connector 5 may also be connected to two or more parts of the remainder of the helmet 1.

In such an arrangement, in the event of an impact to the helmet 1, it is contemplated that the impact will occur on one or a limited number of outer plates 17. Thus, by configuring the helmet such that one or more outer panels 7 are movable relative to the outer layer 2 and any outer panels 7 not subjected to an impact, the surface receiving the impact, i.e. one or a limited number of outer panels 7, is movable relative to the remainder of the helmet 1. In the event of an impact, this may reduce the rotational acceleration of the wearer's head.

It should be understood that this arrangement of outer panels 7 may be added to any of the helmets described herein, i.e. an arrangement having a sliding interface between at least two layers of the helmet 1.

Some helmets, such as the helmets shown in fig. 1-6, are configured to cover the top portion of the head, and the helmet structure described above is suitably located in the helmet to cover the top portion of the head. For example, the helmet may be configured to substantially cover the forehead, the top of the head, the rear brain scoop, and/or the temple of the wearer. The helmet may substantially cover the cranium of the wearer.

Some helmets may be configured to cover other portions of the head, alternatively or additionally to the top portion. For example, a helmet as shown in fig. 8 may cover the cheeks and/or chin of a wearer. Such helmets may be configured to substantially cover the chin of the wearer. Helmets of the type shown in fig. 8 are commonly referred to as full-face helmets. As shown in fig. 8, cheek pads 30 may be provided at both sides (i.e., left and right sides) of the helmet 1. Cheek pads 30 may be provided within the outer shell 2 of the helmet 1 to protect the facial side of the wearer from impact.

The cheek pad 30 may have the same layered structure as the example helmet described above. For example, cheek pad 30 may include one or more energy absorbing layers as described above, and/or interface layers as described above, and/or layers that move relative to one another as described above, alternatively, the layers may be connected by connectors as described above. Alternatively or additionally, the cheek pad 30 itself may be configured to move relative to the outer housing 2 and optionally be connected to the outer housing by a connector as described above.

The helmet described above may be used for a variety of activities. For example, protective helmets may be used for ice hockey, bicycles, skiing, snowboarding, skating, skateboarding, equestrian events, football, baseball, football, soccer, cricket, lacrosse, rock climbing, golf, air guns, and roller skates.

Examples of injuries that can be prevented or alleviated by the above-described helmets include Mild Traumatic Brain Injury (MTBI), such as concussion, and Severe Traumatic Brain Injury (STBI), such as subdural hematoma (SDH), bleeding due to vascular rupture, and Diffuse Axonal Injury (DAI), which can be summarized as overstretching nerve fibers due to high shear deformation in brain tissue.

Depending on the characteristics of the impulse rotation component, such as duration, amplitude and rate of increase, it may suffer from concussion, SDH, DAI or a combination of these injuries. In general, SDH occurs under short duration, high amplitude acceleration conditions, while DAI occurs under longer, more extensive acceleration loads.

Fig. 11 shows a first example of a device for use with a protective headgear according to the present disclosure. In particular, the device may be used with any of the helmets described above or variations thereof.

The device shown in fig. 11 is a cap 40, the cap 40 comprising a rigid housing 41. As shown, the hard shell 41 may be a major component of the cap 40. For example, the headgear typically has a layered structure, and the rigid shell 41 may be the only layer within the cap 40. However, this may not be the case in other examples. Typically, the rigid housing 41 forms a layer covering the inner surface area defined by the cap 40. The rigid housing 41 may form an inner surface of the cap 40 that is arranged to face the wearer's head in normal use, and the rigid housing 41 may be configured to directly contact the wearer's head. Additional layers may be provided on the exterior of the rigid shell 41, i.e., away from the wearer's head.

The rigid shell 41 covers at least a portion of the skull of the wearer. The rigid shell 41 may cover at least the circumference of the wearer's head. The rigid housing 41 may cover a portion of the forehead, the top of the head, a portion of the rear brain scoop, and a portion of both sides of the head of the wearer. Thus, the hard shell 41 may have a substantially hemispherical shape.

The rigid housing 41 may be substantially inelastic in tension. The hard housing 41 may be rigid or may be bendable.

Cap 40 may have a size suitable for wearing by children under 5 years old, preferably under 4 years old. The cap may be sized to fit children with a head circumference of less than 53cm, preferably less than 52cm, preferably less than 51 cm. The cap 40 may be configured to fit a standard head form having such a head circumference.

The standard header may be a european standard EN 960:2006 header of appropriate size.

As shown in fig. 11, cap 40 further includes an adjustment mechanism 50. The adjustment mechanism 50 is configured to adjust the shape of the rigid housing 41 to conform to the individual wearer's head in the first mode of operation. The adjustment mechanism 50 is configured to fix the shape of the housing 41 in the second mode of operation.

As shown in fig. 11, the hard case 41 may be formed as one section. To achieve adjustability, the rigid housing 41 may include an opening 42. The opening 42 may extend from the edge of the rigid shell 41 to the crown portion. The opening 42 may be configured such that portions of the rigid housing 41 on opposite sides of the opening 42 are movable relative to each other to close or widen the opening 42. Thus, the shape of the hard shell 41 may be adjusted to fit the wearer.

As shown in fig. 11, the adjustment mechanism 50 may include a strap 51. The strap 51 may be connected to the rigid housing 41 on one side of the opening, such as by a fixed connector 52, and configured to span the opening 42. The strap 51 may be connected to the rigid housing 41 on the other side of the opening 42 by an adjustable connector 53. The adjustable connector 53 may be connected to the strip 51 at a plurality of locations (either discretely or continuously) along the length of the strip 41. The adjustable connector 53 is operable in two modes, a first mode in which the connection with the strap 51 is adjustable and a second mode in which the connection is fixed.

In the example shown in fig. 11, the strap 41 may include one or more slots configured to engage with protrusions in the adjustable connector 53. The protrusions may be selectively engageable with the slots to allow adjustment or securement of the connection. This arrangement may be similar to that of a ligature tape (zip-tie).

Fig. 12 shows the cap 40 of fig. 11 adjusted to fit a smaller head circumference.

Fig. 13 shows an example cap 40 with an alternative adjustment mechanism 50. As shown, the adjustment mechanism may include a strap 54 integral with the rigid housing 41 on one side of the opening 42. The strip may include a groove 55 along its length. The slot may be configured to engage with the adjustable connector 56. The slot 55 may slide over an adjustable connector 56 that may selectively secure the strap 54 in place.

Fig. 14 shows an example cap 40 with another alternative adjustment mechanism 50. As shown, the adjustment mechanism may include a wire 57, the wire 57 being threaded (e.g., multiple times) across the opening 42 via a retainer 58. The wire 57 is connected to an adjustor 59, which adjustor 59 can be adjusted to tighten or loosen the wire to close or widen the opening 42.

Fig. 15 shows an example cap 40 in which a rigid housing 41 is provided in a plurality of sections, with openings 42 provided between each section 42. As shown, cap 40 may include an adjustment mechanism similar to that shown in fig. 14. The adjustment mechanism may include a wire 57 threaded across the opening 42 via a retainer 58. The wire 57 is connected to an adjustor 59, which adjustor 59 can be adjusted to tighten or loosen the wire to close or widen the opening 42.

In each of the above examples, the cap 40 is configured such that the hard shell 41 substantially maintains a fixed shape (during normal use) and is subject to forces applied to the cap 40 during impact. If the cap 40 forms part of a one-piece protective headgear, this may be an impact on the headgear.

In this case, fixing the shape may mean that the system formed by the hard shell 41 and the adjustment mechanism 50 behaves as if the system were not adjustable, for example as if the adjustment mechanism 50 were replaced by the same section of the hard shell as the rest of the hard shell.

In each of the above examples, the adjustment mechanism 50 may be configured to be able to adjust the shape of the hard case 41 such that the average gap size between the hard case 41 and the standard head form is not more than 2mm at the circumferential portion of the hard case 41 or over the entire hard case 41. This is easier to measure for standard head types than for real heads, but also for real heads. Fig. 16 shows a gap 70 between the hard shell 41 and the outer surface of the head form 60. The adjustment mechanism 50 may be configured to be able to adjust the shape of the hard housing 41 such that the average gap size is not greater than 1mm.

The adjustment mechanism 50 may be configured to be able to adjust the shape of the hard case 41 such that the maximum gap size between the hard case 41 and the standard head form 60 is not more than 2mm at the circumferential portion of the hard case 41 or over the entire hard case 41. The adjustment mechanism 50 may be configured to be able to adjust the shape of the hard housing 41 such that the maximum gap size is not greater than 1.5mm.

The gap size may be calculated based on a direction perpendicular to the surface of the head form at a given location. The average gap size may be calculated as the average gap size at a plurality of locations around the head form.

Simulations indicate that a small gap 70 can reduce stress on the skull due to impact on the child's head.

In each of the above examples, the hardness of the system formed by the hard shell 41 and the adjustment mechanism 50 in the second mode may be such that during an impact, the average gap size between the hard shell 41 and the standard head form increases by no more than 2mm at the circumferential portion of the hard shell 41 or over the entire hard shell 41. This configuration may result in an increase in average gap size of no more than 1.5mm during impact.

The hardness of the system formed by the hard shell 41 and the adjustment mechanism 50 in the second mode may be such that during an impact, the average displacement between the opposing surfaces of the hard shell 41 facing the standard head form is no more than 2mm, either at a circumferential portion of the hard shell 41 or over the entire hard shell 41. This configuration may be such that the average displacement increases by no more than 1.5mm during an impact.

The stiffness of the system formed by the hard shell 41 and the adjustment mechanism 50 in the second mode may be such that during an impact, the maximum gap size between the hard shell 41 and the standard head form increases by no more than 2mm at the circumferential portion of the hard shell 41 or over the entire hard shell 41. This configuration may allow the maximum gap size to increase by no more than 1.5mm during an impact.

The stiffness of the system formed by the hard shell 41 and the adjustment mechanism 50 in the second mode may be such that during an impact, the maximum displacement between the opposing surfaces of the hard shell 41 facing the wearer's head is no more than 2mm, either at a circumferential portion of the hard shell 41 or over the entire hard shell 41. This configuration may be such that the maximum displacement increases by no more than 1.5mm during an impact.

The impact may be experienced during a standard drop test, for example a shock absorption test according to european standard EN1080, which drops a standard head form from 1.5m onto a flat anvil to have an impact speed of 5.4 m/s.

Simulations indicate that skull stress can be reduced by a system with the following hardness: this stiffness ensures that a small gap size is maintained between the hard shell 41 and the wearer.

The material forming the sections of the hard shell 41 has a young's modulus of at least 1GPa, preferably at least 2 GPa.

The material forming the hard case 41 may be polycarbonate. The thickness of the material may be greater than 0.5mm and not greater than 3mm, preferably between 1mm and 2mm, for example 1.5mm. The strips 51 may be formed of the same material or different materials.

The hardness of the system formed by the hard shell 41 and the adjustment mechanism 50 in the second mode may be at least equal to the hardness of a complete, non-adjustable hard shell formed from a material having a young's modulus of at least 1GPa, preferably at least 2 GPa.

In some examples, the hardness of the hard shell 41 may be different in different portions of the hard shell.

Generally, the headgear includes a soft, comfort pad at the interface with the head to make the headgear more comfortable to wear. However, the cap 40 may be devoid of compressible material, such as comfort pad, more inward than the rigid shell 41 relative to the wearer's head, particularly around the circumferential portion of the rigid shell 41.

As described above, the cap 40 may form part of a protective headgear. For example, the cap 40 may be an additional layer to the example helmet described above, or instead of the interface layer 4 of the helmet. For example, the cap 40 may be used as an interface layer as described above with respect to the example helmet.

According to some examples, cap 40 may be configured to rotate relative to at least one protective layer (e.g., an energy absorbing layer and/or a hard outer shell) under an oblique impact to the protective layer. The headgear may also include at least one connector configured to connect the cap 40 and the at least one protective layer while allowing relative rotation.

A sliding interface may be provided between the cap 40 and the at least one protective layer. In normal use, the surface of the cap 40 that is disposed away from the wearer's head may be a low friction surface. The low friction surface may be provided by material properties forming one or more sections of the hard shell 41.

Alternatively, a shear interface may alternatively be provided between the cap 40 and the at least one protective layer.

Variations of the above examples are possible in light of the above teachings. It will be appreciated that the invention can be practiced otherwise than as specifically described herein without departing from the spirit and scope of the invention.

Claims

1. A cap for use with a protective headgear, comprising:

a hard shell forming a layer covering an inner surface area defined by the cap and formed by one or more sections;

an adjustment mechanism configured to adjust the shape of the rigid shell to conform to an individual wearer's head in a first mode of operation, and to fix the shape of the shell in a second mode of operation; and wherein

The cap is configured such that the rigid shell substantially maintains a fixed shape during normal use and when subjected to forces applied to the cap during impact.

2. The cap of claim 1, wherein the rigid shell forms an inner surface of the cap, the inner surface being arranged to face the wearer's head in normal use, and the rigid shell is configured to directly contact the wearer's head.

3. A cap according to any preceding claim, wherein in normal use the cap is free of compressible material more inwardly than the rigid shell relative to the wearer's head.

4. A cap according to any preceding claim, wherein the adjustment mechanism is configured to be able to adjust the shape of the hard shell such that the average gap size between the hard shell and standard head form is not greater than 2mm over a circumferential portion of the hard shell or over the entire hard shell.

5. The cap of claim 4, wherein the adjustment mechanism is configured to be able to adjust the shape of the rigid shell such that the average gap size is no greater than 1mm.

6. A cap according to any preceding claim, wherein the hardness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during impact the average gap size between the hard shell and the standard head form increases by no more than 2mm at a circumferential portion of the hard shell or over the hard shell.

7. The cap of claim 6, wherein the average gap size increases by no more than 1.5mm during impact.

8. Cap according to any preceding claim, wherein the hardness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during impact the average displacement between the opposing surfaces of the hard shell facing the standard head form is not more than 2mm at a circumferential portion of the hard shell or over the hard shell.

9. The cap of claim 8, wherein the average displacement increases by no more than 1.5mm during impact.

10. A cap according to any preceding claim, wherein the adjustment mechanism is configured to be able to adjust the shape of the hard shell such that the maximum gap size between the hard shell and standard head form is not greater than 2mm at a circumferential portion of the hard shell or over the hard shell.

11. The cap of claim 10, wherein the adjustment mechanism is configured to be able to adjust the shape of the rigid housing such that the maximum gap size is no greater than 1mm.

12. A cap according to any preceding claim, wherein the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and the standard head form is such that during impact the maximum gap dimension between the hard shell and the standard head form increases by no more than 2mm at a circumferential portion of the hard shell or over the hard shell.

13. The cap of claim 12, wherein the maximum gap size increases by no more than 1.5mm during impact.

14. A cap according to any preceding claim, wherein the stiffness of the system formed by the hard shell, the adjustment mechanism in the second mode and a standard head form is such that during an impact the maximum displacement between the opposing surfaces of the hard shell facing the wearer's head is no more than 2mm at a circumferential portion of the hard shell or over the hard shell.

15. The cap of claim 14, wherein the maximum displacement increases no more than 1.5mm during impact.

16. A cap according to any preceding claim, wherein the material forming the region of the rigid shell has a young's modulus of at least 1 GPa.

17. A cap according to any preceding claim, wherein the region forming the rigid shell is formed from polycarbonate.

18. A cap according to any preceding claim, wherein the rigid shell is at least 1mm thick.

19. Cap according to any preceding claim, wherein, in normal use, the surface of the cap arranged to face away from the wearer's head is a low friction surface.

20. The cap of claim 19, wherein the low friction surface is provided by material properties forming one or more sections of the hard shell.

21. A cap according to any preceding claim, wherein in normal use the rigid housing is arranged to cover at least a portion of the forehead, the top of the head, a portion of the rear brain scoop and a portion of both sides of the head of a wearer.

22. A protective headgear comprising:

a cap according to any preceding claim; and

at least one protective layer covering the cap.

23. The headgear of claim 22, wherein the cap is configured to rotate relative to the at least one protective layer under an oblique impact to the protective layer.

24. The headgear of claim 23, further comprising at least one connector configured to connect the cap and the at least one protective layer while allowing relative rotation.

25. The headgear of claim 23 or 24, wherein a sliding interface is provided between the cap and the at least one protective layer.

26. The headgear of claim 23 or 24, wherein a shear interface is provided between the cap and the at least one protective layer.

27. The headgear according to any one of claims 22-26, wherein the at least one protective layer comprises an energy absorbing layer.

28. The headgear of any one of claims 22-26, wherein the at least one protective layer comprises a hard outer hard shell.

29. A method of protecting a wearer of a headgear from head injury, comprising:

wrapping a wearer's head in a cap, the cap comprising:

an adjustment mechanism for adjusting the shape of the hard shell in a first mode of operation, and configured to fix the shape of the hard shell in a second mode of operation; and wherein

The cap is configured such that the rigid shell substantially maintains a fixed shape during normal use and when subjected to forces applied to the cap during impact;

the method includes adjusting a shape of the rigid shell to conform to the wearer's head and securing the shape.

30. The method of claim 29, wherein the shape of the rigid shell is adjusted such that in normal use, the average gap size between the rigid shell and the wearer's head is no greater than 2mm.

31. The cap of claim 30, wherein the shape of the rigid shell is adjusted such that the average gap size is no greater than 1mm.