helmet

Abstract

To provide a helmet.SOLUTION: There is provided a helmet (1). The helmet includes an outer shell (2); and a head mount (20) configured to be mounted over a top of a head of a helmet wearer. The head mount is suspended within the outer shell such that, in use, an air gap (21) is provided between the head mount and the outer shell. The helmet further includes a head engagement device (40). The head engagement device is mounted on a surface of the head mount, the head engagement device is configured to face a head of a wearer of the helmet, and the head engagement device is movable relative to the head mount. A low friction interface is provided between the head mount and the head engagement device.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a helmet. [Background technology]

[0002] Helmets are known for use in a variety of activities, including combat and industrial purposes, such as protective helmets for soldiers and hard hats or helmets used by builders, miners, or industrial machine operators. Helmets are also common in sporting activities. For example, protective helmets may be used in ice hockey, cycling, motorcycling, motor car racing, skiing, snowboarding, skating, skateboarding, equestrian, American football, baseball, rugby, soccer, cricket, lacrosse, mountain climbing, golf, airsoft, roller derby, and paintball.

[0003] Helmets can be of a fixed size or can be adjustable to fit different head sizes and shapes. In some types of helmets, for example, commonly ice hockey helmets, adjustability can be provided by moving parts of the helmet to change the helmet's exterior and interior dimensions. This can be achieved by having a helmet with two or more parts that can move relative to one another. In other cases, for example, commonly cycling helmets, the helmet is provided with a mounting device for securing the helmet to a user's head, and the mounting device can change dimensions to fit the user's head while the main body or shell of the helmet remains the same size. In some cases, comfort padding within the helmet can act as a mounting device. Mounting devices can also be provided in the form of multiple physically separate parts, e.g., multiple comfort pads that are not interconnected to one another. Such mounting devices for seating the helmet on a user's head can be used with additional straps (e.g., chin straps) to further secure the helmet in place. Combinations of these adjustment mechanisms are also possible.

[0004] Helmets are often made of an outer shell (which is usually rigid and made from plastic or composite materials) and an energy-absorbing layer (often referred to as a liner). In other arrangements (such as rugby scrum caps), the helmet may not have a rigid outer shell and may be entirely flexible. In either case, protective helmets nowadays must be designed to meet certain legal requirements, which relate, among other things, to the maximum acceleration that can occur at the center of gravity of the brain at a specific load. Typically, tests are performed in which what is known as a dummy skull equipped with a helmet is subjected to a radial blow towards the head. This results in modern helmets having good energy absorption capabilities in the case of a radial blow to the skull. Efforts have also been made to develop helmets to reduce the energy transferred from oblique hits (i.e., which combine both tangential and radial components) by absorbing or dissipating rotational energy and / or redirecting it into translational rather than rotational energy (e.g., WO2001 / 045526 and WO2011 / 139224, both of which are incorporated herein by reference in their entireties).

[0005] Such an oblique impact (in the absence of protection) results in both translational and angular acceleration of the brain. Angular acceleration causes the brain to rotate within the skull, causing injury to the elements of the body connecting the brain to the skull and to the brain itself.

[0006] Examples of rotational injuries include mild traumatic brain injury (MTBI), such as a concussion, and severe traumatic brain injury (STBI), such as a subdural hematoma (SDH), which causes bleeding as a result of blood vessel rupture, and diffuse axonal injury (DAI), which can be summarized as overstretching of nerve fibers as a result of high shear deformation in brain tissue.

[0007] Depending on the characteristics of the rotational force, such as duration, amplitude, and rate of increase, one may suffer a concussion, SDH, DAI, or a combination of these injuries. Generally speaking, SDH occurs in cases of short duration and large amplitude acceleration, while DAI occurs in cases of longer and more widespread acceleration loads.

[0008] In helmets such as those disclosed in WO2001 / 045526 and WO2011 / 139224, which can reduce rotational energy transmitted to the brain caused by an oblique impact, two parts of the helmet can be configured to slide relative to each other at a sliding interface following an oblique impact. Summary of the Invention [Problem to be solved by the invention]

[0009] In some helmets, the head-mounted device is suspended within and separate from the rigid outer shell. Such helmets are simple and inexpensive to manufacture and may provide sufficient protection from radial impacts for a particular helmet application. However, it may be desirable to improve the performance of such helmets, for example, in the event of an oblique impact, preferably without substantially increasing manufacturing cost and / or effort. [Means for solving the problem]

[0010] According to an aspect of the present disclosure, there is provided a helmet, the helmet comprising: outer shell and; a head mount configured to be worn over the top of the helmet wearer's head; Including, The head mount is suspended within the outer shell such that, when in use, an air gap is provided between the head mount and the outer shell; the helmet further includes a head-engaging device mounted on a surface of the head mount, the head-engaging device configured to face a head of a wearer of the helmet, and the head-engaging device is movable relative to the head mount; A helmet is provided in which a low friction interface is provided between the head mount and the head engaging device.

[0011] In one arrangement, the head-engaging device is connected to a head mount.

[0012] In one arrangement, the head mount includes a plurality of straps configured to extend across the top of the helmet wearer's head and connected to connection points on the outer shell.

[0013] In one arrangement, the head mount includes a plurality of straps extending between opposing pairs of connection points.

[0014] In one arrangement, at least two straps are connected to one another.

[0015] In one arrangement, the head-engaging device is connected to the head mount by at least one connector that engages with one of the straps.

[0016] In one arrangement, at least one connector has a first end and a second end, both of which are joined to the head-engaging device at respective first and second locations on the head-engaging device; and a strap is positioned between the connector and the head-engaging device in a region between the first and second locations on the head-engaging device.

[0017] In some arrangements, the strap is not rigidly secured to parts of the connector, allowing the strap to slide relative to the connector.

[0018] In one arrangement, the connector is formed from an elongated section of material, optionally from one of a cord, band, or tape.

[0019] In one arrangement, the connectors are formed from separate pieces of the material.

[0020] In one arrangement, multiple connectors are formed from a single piece section of the material.

[0021] In one arrangement, the head mount includes at least one strap connected to a front portion of the outer shell that extends in a direction toward the rear of the helmet.

[0022] In some arrangements, the head engaging device is provided as a single component.

[0023] In some arrangements, the head engaging device is formed from a number of separate sections.

[0024] In one arrangement, the head mount includes a head ring configured to engage at least the forehead of a helmet wearer; The head-engaging device includes a crown region and a forehead region, the crown region configured to be positioned between the top of the helmet wearer's head and the head mount, and the forehead region configured to be positioned adjacent to the head ring.

[0025] In some arrangements, the head engaging device further includes an intermediate region connecting the crown region to the frontal region.

[0026] In one arrangement, the head-engaging device frontal region is positioned between the helmet wearer's forehead and the head ring.

[0027] In one arrangement, the head ring is positioned between the helmet wearer's forehead and the frontal region of the head-engaging device.

[0028] In one arrangement, the helmet further includes a front pad positioned adjacent the forehead of the helmet wearer.

[0029] In one arrangement, the anterior pad is connected to at least one of the head ring, the frontal region of the head engaging device, and the outer shell.

[0030] In one arrangement, the front pads are connected by elastic connectors that are configured to allow the front pads to move relative to the components to which they are connected.

[0031] In one arrangement, the head-engaging device includes one or more pads provided on a surface of the head-engaging device that faces the head of the helmet wearer.

[0032] In one arrangement, the head-engaging device comprises a plate of material, optionally shaped to conform to the head of a helmet wearer.

[0033] In one arrangement, the head engaging device includes a plurality of holes configured to provide at least one of a location for a connector to mate to the head engaging device and ventilation.

[0034] In one arrangement, a low-friction interface is provided by a low coefficient of friction between the surface of the head mount and the head-engaging device.

[0035] In one arrangement, in the absence of an impact to the helmet, the separation between the outer shell and the head mount at a location corresponding to the top of the wearer's head provided by the air gap is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, optionally at least 40 mm.

[0036] The invention is explained in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 shows a cross section through a helmet for providing protection against oblique impacts. [Figure 2] 2 is a diagram illustrating the functional principle of the helmet of FIG. 1. [Figure 3A] 1. FIG. 4 is a diagram showing a modified example of the structure of the helmet of FIG. [Figure 3B] 1. FIG. 4 is a diagram showing a modified example of the structure of the helmet of FIG. [Figure 3C] 1. FIG. 4 is a diagram showing a modified example of the structure of the helmet of FIG. [Figure 4] 10A and 10B are diagrams showing schematic views of alternative arrangements of the helmet; [Figure 5] 10A and 10B are diagrams showing schematic views of alternative arrangements of the helmet; [Figure 6] 10A and 10B show schematic cross-sectional views of alternative helmet arrangements; [Figure 7] FIG. 7 shows the inside of an example helmet according to the arrangement shown in FIG. 6. [Figure 8] FIG. 8 shows a connector for use in a helmet of the arrangement shown in FIG. 7. [Figure 9] FIG. 8 shows a connector for use in a helmet of the arrangement shown in FIG. 7. [Figure 10] FIG. 8 shows a connector for use in a helmet of the arrangement shown in FIG. 7. [Figure 11]FIG. 10 shows the inside of a further example of a helmet. [Figure 12] FIG. 10 shows the inside of a further example of a helmet. [Figure 13] FIG. 10 shows the inside of a further example of a helmet. [Figure 14] FIG. 10 shows the inside of a further example of a helmet. [Figure 15] FIG. 15 shows the helmet of FIG. 14 from the side. DETAILED DESCRIPTION OF THE INVENTION

[0038] The thickness proportions of the various layers in the helmet shown in the figures have been exaggerated in the drawings for clarity and can, of course, be adapted according to need and desire.

[0039] Figure 1 shows a first helmet 1 of the kind discussed in WO 01 / 45526, which is intended to provide protection against oblique impacts. This type of helmet can be any of the types of helmets discussed above.

[0040] The protective helmet 1 is constructed by an outer shell 2 and an inner shell 3 arranged inside the outer shell 2, the inner shell 3 being intended to come into contact with the wearer's head.

[0041] A sliding layer 4 (also called a slide promoter or low-friction layer) is disposed between the outer shell 2 and the inner shell 3 and can enable displacement between the outer shell 2 and the inner shell 3. Among other things, as discussed below, the sliding layer 4 or slide promoter can be configured to allow sliding to occur between the two parts during an impact. For example, it can be configured to enable sliding under forces associated with an impact to the helmet 1 that is expected to be survivable for the wearer of the helmet 1. In some arrangements, it may be desirable to configure the sliding layer 4 to have a coefficient of friction between 0.001 and 0.3 and / or below 0.15.

[0042] In the depiction of FIG. 1, one or more connecting members 5 may be disposed within the edge portion of the helmet 1, the one or more connecting members 5 interconnecting the outer shell 2 and the inner shell 3. In some arrangements, the connectors may resist mutual displacement between the outer shell 2 and the inner shell 3 by absorbing energy. However, this is not required. Furthermore, even if this feature is present, the amount of energy absorbed is typically minimal compared to the energy absorbed by the inner shell 3 during an impact. In other arrangements, the connecting members 5 may not be present at all.

[0043] Furthermore, the location of these connecting members 5 may be varied (eg, positioned away from the edge portions and connecting the outer shell 2 and inner shell 3 through the sliding layer 4).

[0044] The outer shell 2 is preferably relatively thin and strong to withstand various types of impacts. The outer shell 2 may be made of a polymer material such as polycarbonate (PC), polyvinyl chloride (PVC), or acrylonitrile butadiene styrene (ABS). Advantageously, the polymer material may be fiber-reinforced using materials such as fiberglass, aramid, Twaron, carbon fiber, or Kevlar.

[0045] The inner shell 3 is considerably thicker and acts as an energy-absorbing layer. As such, it can attenuate or absorb impacts to the head. It can advantageously be made from foam materials such as expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), vinyl nitrile foam; or other materials that form, for example, honeycomb-like structures; or strain-rate sensitive foams, such as those commercially available under the brand names Poron™ and D3O™. The construction can be varied in different ways, for example with multiple layers of different materials, as will appear below.

[0046] The inner shell 3 is designed to absorb the energy of an impact. Although other elements of the helmet 1 will absorb that energy to a limited extent (e.g., the rigid outer shell 2 or the so-called "comfort padding" provided in the inner shell 3), it is not their primary purpose and their contribution to energy absorption is minimal compared to that of the inner shell 3. Indeed, some other elements, such as comfort padding, may be made from "compressible" materials and, as such, may be considered "energy absorbers" in other contexts, but in the field of helmets, it is well recognized that compressible materials are not necessarily "energy absorbers" in the sense of absorbing a significant amount of energy during an impact for the purpose of reducing injury to the helmet wearer.

[0047] A number of different materials and embodiments can be used as the sliding layer 4 or slide facilitator, such as oil, Teflon, microspheres, air, rubber, fabric materials such as polycarbonate (PC), felt, etc. Such layers can have thicknesses of approximately 0.1 to 5 mm, although other thicknesses can be used depending on the material selected and the performance desired. Also, the number of sliding layers and their positioning can be varied, an example of which is discussed below (with reference to FIG. 3b).

[0048] As connecting members 5, for example, deformable strips of plastic or metal can be used, which are anchored in an appropriate manner in the outer and inner shells.

[0049] Figure 2 shows the functional principle of the protective helmet 1, where the helmet 1 and the wearer's skull 10 are assumed to be semi-cylindrical in shape, with the skull 10 resting on a longitudinal axis 11. Torsional forces and torques are transmitted to the skull 10 when the helmet 1 is subjected to an oblique impact K. The impact force K is transmitted to the protective helmet 1 in the form of a tangential force K. T and radial force K R In this particular context, the tangential force K that rotates the helmet T and only its effects are of interest.

[0050] As can be seen, force K causes a displacement 12 of the outer shell 2 relative to the inner shell 3, and the connecting member 5 is deformed. A significant reduction in the torsional forces transmitted to the skull 10 can be obtained with such an arrangement. A typical reduction can be approximately 25%, but in some cases a reduction of as much as 90% may be possible. This is the result of a sliding motion between the inner shell 3 and the outer shell 2, which reduces the amount of energy transmitted into radial acceleration.

[0051] It is also possible, but not shown, that the sliding movement occurs in the circumferential direction of the protective helmet 1. This may be as a result of a circumferential angular rotation between the outer shell 2 and the inner shell 3 (i.e., during an impact, the outer shell 2 may be rotated by a predetermined circumferential angle relative to the inner shell 3).

[0052] Other configurations of the protective helmet 1 are also possible. Some possible variations are shown in FIG. 3. In FIG. 3a, the inner shell 3 is constructed from a relatively thin outer layer 3'' and a relatively thick inner layer 3'. The outer layer 3'' is preferably harder than the inner layer 3', which helps promote sliding relative to the outer shell 2. In FIG. 3b, the inner shell 3 is constructed in the same manner as in FIG. 3a. However, in this case, there are two sliding layers 4, with an intermediate shell 6 between them. The two sliding layers 4 can be embodied differently and made of different materials, if desired. One possibility is, for example, to have lower friction in the outer sliding layer than in the inner sliding layer. In FIG. 3c, the outer shell 2 is embodied differently from the previous one. In this case, a harder outer layer 2'' covers a softer inner layer 2'. The inner layer 2' can, for example, be of the same material as the inner shell 3.

[0053] Figure 4 shows a second helmet 1 of the kind discussed in WO2011 / 139224, which is also intended to provide protection against oblique impacts, and this type of helmet could be any of the types of helmets discussed above.

[0054] In FIG. 4, helmet 1 includes an energy-absorbing layer 3 similar to the inner shell 3 of the helmet of FIG. 1. The outer surface of energy-absorbing layer 3 may be provided from the same material as energy-absorbing layer 3 (i.e., no additional outer shell may be present), or the outer surface may be a rigid shell 2 (see FIG. 5) equivalent to the outer shell 2 of the helmet shown in FIG. 1. In that case, rigid shell 2 may be made from a different material than energy-absorbing layer 3. Helmet 1 of FIG. 4 has multiple vents 7, which are optional and extend through both energy-absorbing layer 3 and outer shell 2, thereby allowing airflow through helmet 1.

[0055] An interface layer 13 (also referred to as an attachment device) is provided for interfacing with the wearer's head (and / or for attaching the helmet 1 to the wearer's head). As discussed above, this may be desirable when the sizes of the energy-absorbing layer 3 and the rigid shell 2 cannot be adjusted, as it allows different head sizes to be accommodated by adjusting the size of the attachment device 13. The attachment device 13 may be made from an elastic or semi-elastic polymer material, such as PC, ABS, PVC, or PTFE, or a natural fiber material, such as cotton cloth. For example, a textile cap or net could form the attachment device 13.

[0056] Although mounting device 13 is shown as including a headband portion with additional strap portions extending from the front, rear, left, and right sides, the specific configuration of mounting device 13 can vary depending on the helmet configuration. In some cases, the mounting device can be more like a continuous sheet, perhaps with holes or gaps (e.g., corresponding to the locations of vents 7) to allow airflow through the helmet.

[0057] 4 also shows an optional adjustment device 6 for adjusting the diameter of the headband of the attachment device 13 for a particular wearer. In other arrangements, the headband can be an elastic headband, in which case the adjustment device 6 can be omitted.

[0058] The slide facilitators 4 are provided radially inward of the energy absorbing layer 3. The slide facilitators 4 are adapted to slide against the energy absorbing layer or against a mounting device 13 provided for mounting the helmet on the wearer's head.

[0059] The slide facilitators 4 are provided to aid in the sliding of the energy absorbing layer 3 relative to the mounting device 13 in the same manner as discussed above. The slide facilitators 4 can be, or can be coated with, a material that has a low coefficient of friction.

[0060] As such, in the helmet of FIG. 4, the slide facilitator may be provided on the innermost side of the energy absorbing layer 3 facing the mounting device 13 or may be integral therewith.

[0061] However, it is equally conceivable that slide facilitators 4 may be provided on or integrated into the outer surface of the mounting device 13 for the same purpose of providing slidability between the energy absorbing layer 3 and the mounting device 13. That is, in certain arrangements, the mounting device 13 itself may be adapted to act as slide facilitators 4 and may include a low friction material.

[0062] In other words, the slide facilitators 4 are provided radially inward of the energy absorbing layer 3. Alternatively, slide facilitators may be provided radially outward of the mounting device 13.

[0063] When the attachment device 13 is formed as a cap or net (as discussed above), the slide facilitator 4 may be provided as a patch of low friction material.

[0064] The low-friction material can be a waxy polymer, such as PTFE, ABS, PVC, PC, nylon, PFA, EP, PE, and UHMWPE, or a powder material that can be infused with a lubricant. The low-friction material can be a fabric material. As discussed, the low-friction material can be applied to either or both the slide facilitator and the energy-absorbing layer.

[0065] The mounting device 13 may be secured to the energy-absorbing layer 3 and / or outer shell 2 by fastening members 5, such as the four fastening members 5a, 5b, 5c, and 5d in FIG. 4 , which may be adapted to absorb energy by deforming in an elastic, semi-elastic, or plastic manner. However, this is not required. Furthermore, even if this feature is present, the amount of energy absorbed is typically minimal compared to the energy absorbed by the energy-absorbing layer 3 during an impact.

[0066] According to the arrangement shown in FIG. 4, the four fixing members 5a, 5b, 5c and 5d are suspension members 5a, 5b, 5c, 5d having first and second portions 8, 9, the first portions 8 of the suspension members 5a, 5b, 5c, 5d being adapted to be fixed to the mounting device 13 and the second portions 9 of the suspension members 5a, 5b, 5c, 5d being adapted to be fixed to the energy absorbing layer 3.

[0067] Figure 5 shows the arrangement of a helmet similar to that in Figure 4 when placed on a wearer's head. The helmet 1 of Figure 5 includes a hard outer shell 2 made from a different material than the energy absorbing layer 3. In contrast to Figure 4, in Figure 5 the mounting device 13 is fixed to the energy absorbing layer 3 by two fixing members 5a, 5b, which are adapted to absorb energy and forces elastically, semi-elastically or plastically.

[0068] A forward oblique impact I that generates a rotational force on the helmet is shown in FIG. 5. The oblique impact I causes the energy-absorbing layer 3 to slide relative to the mounting device 13. The mounting device 13 is secured to the energy-absorbing layer 3 by securing members 5a and 5b. For clarity, only two such securing members are shown, but in reality, many such securing members may be present. The securing members 5 may absorb the rotational force by deforming elastically or semi-elastically. In other arrangements, the deformation may be plastic and may even result in the shedding of one or more of the securing members 5. In the case of plastic deformation, at least the securing members 5 will need to be replaced after the impact. In some cases, a combination of plastic and elastic deformation in the securing members 5 may occur; i.e., some securing members 5 break and plastically absorb the energy, while other securing members deform elastically and absorb the force.

[0069] Generally, in the helmets of FIGS. 4 and 5, during an impact, the energy-absorbing layer 3 acts as a shock absorber by compressing in the same manner as the inner shell of the helmet of FIG. 1. If an outer shell 2 is used, it helps spread the impact energy across the energy-absorbing layer 3. Additionally, the slide promoter 4 allows sliding between the mounting device and the energy-absorbing layer. This allows a controlled manner to dissipate energy that would otherwise be transferred to the brain as rotational energy. The energy can be dissipated through frictional heat, energy-absorbing layer deformation, or deformation or displacement of the fixation members. The reduced energy transfer results in reduced rotational accelerations affecting the brain, thus reducing rotation of the brain within the skull. This reduces the risk of rotational injuries, including MTBI and STBI, e.g., subdural hematoma, SDH, vascular rupture, concussion, and DAI.

[0070] FIG. 6 shows a schematic cross-section of a helmet of a different type than those shown in FIGS. 1 through 5. In a helmet 1 such as that shown in FIG. 6, a head mount 20 is suspended within an outer shell 2, providing an air gap 21 between the outer shell 2 and the head mount 20. The head mount 20 may be connected to the outer shell 2 by a connector 25. This type of helmet is commonly used for industrial purposes, such as by construction workers, miners, or industrial machine operators. However, helmets based on such an arrangement may also be used for other purposes. In some applications, the outer shell 2 may be a rigid shell made from a polymer material (e.g., polycarbonate (PC), polyvinyl chloride (PVC), high-density polyethylene (HDPE), or acrylonitrile butadiene styrene (ABS)). Advantageously, the polymer material may be fiber-reinforced using materials such as fiberglass, aramid, Twaron, carbon fiber, or Kevlar.

[0071] While the following disclosure relates to an example of a helmet 1 in which the outer shell 2 is formed solely from a rigid shell, it should be recognized that the disclosed arrangements are applicable to other helmet configurations. For example, the outer shell can alternatively or additionally include a layer of energy-absorbing material. Such energy-absorbing material can be made from foam materials such as expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), vinyl nitrile foam, or other materials that form honeycomb-like structures, or strain-rate sensitive foams, such as those sold under the brand names Poron™ and D3O™.

[0072] If used, a layer of energy-absorbing material may be provided as a shell over substantially all of the surface of the rigid shell facing the wearer's head, although ventilation holes may also be provided. Alternatively or additionally, a localized region of energy-absorbing material may be provided between the rigid shell and the head mount. For example, a band of energy-absorbing material may be provided around the lower edge of the rigid shell and / or a section of energy-absorbing material may be provided positioned above the top of the wearer's head.

[0073] In helmets such as that shown in FIG. 6, providing an air gap 21 between the inner surface of the outer shell 2 and the head mount 20 is intended to ensure that the load caused by an impact on the outer shell 2 is spread across the wearer's head. In particular, the load is not localized over a point on the wearer's head adjacent the point of impact on the helmet 1. Instead, the load is spread across the outer shell 2 and then across the head mount 20 and thus across the wearer's skull.

[0074] During such an impact, the energy of the impact can be absorbed by deformation of parts of the helmet (such as the head mount), reducing the size of the air gap. Thus, the size of the air gap 21 between the outer shell 2 and the head mount 20 can be chosen to ensure that under an impact on the helmet that the helmet is designed to withstand, the head mount 20 does not come into contact with the outer shell 2, i.e., the air gap 21 is not completely eliminated so that the impact can be transmitted directly from the hard shell to the head mount.

[0075] In one arrangement, helmet 1 may be configured so that, in the absence of an impact to the helmet, the separation between outer shell 2 and head mount 20 at a location corresponding to the top of the wearer's head is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, and optionally at least 40 mm. The magnitude of the impact helmet 1 is designed to withstand, and thus the size of air gap 21, may depend on the intended use of helmet 1. It should be understood that the size of air gap 21 may be different in different locations depending on the intended use of the helmet. For example, air gap 21 may be smaller at the front, back, or sides of the helmet than it is at the location corresponding to the top of the wearer's head.

[0076] In helmet arrangements including energy-absorbing material, the energy-absorbing material can contribute to the helmet's ability to withstand a radial impact. In particular, it will be recognized that in arrangements where the energy-absorbing material is positioned in the air gap between the outer shell 2 and the head mount 20 at a location corresponding to the top of the wearer's head, the gap between the head mount and the surface of the energy-absorbing layer will be smaller than the gap between the outer shell and the head mount, and may be eliminated entirely. Additionally, as a result of the contribution of the energy-absorbing material in the event of a radial impact, a smaller gap between the outer shell and the head mount may be required than would be the case without the energy-absorbing material.

[0077] The head mount 20 may be provided in any form that can conform to the wearer's head (or at least the top of the wearer's head) and function to secure the helmet to the wearer's head or contribute to securing the helmet to the wearer's head. In some configurations, it may assist in securing the helmet 1 to the wearer's head, but this is not required. In some arrangements, the head mount 20 may include a head band (or head ring) that at least partially encircles the wearer's head. Alternatively or additionally, the head mount 20 may include one or more straps that extend across the top of the wearer's head. Alternatively or additionally, the head mount 20 may include a cap or shell that encapsulates the upper portion of the wearer's head. The straps or bands that form part of the head mount may be formed from nylon. Alternatively or additionally, other materials may be used.

[0078] Figure 7 shows an arrangement in which a helmet of the type shown diagrammatically in Figure 6 has features in accordance with the present disclosure. As shown, the head mount includes a plurality of straps 20 that extend across the top of the helmet wearer's head. The straps 20 may be connected at connection points to the outer shell 2 by any of a number of known methods. For example, the outer shell 2 may be molded to include a socket, and a connector 25 may be inserted into the socket.

[0079] In the arrangement shown in FIG. 7 , the head mount is formed from two straps 20, each extending between a pair of connectors 25 positioned so that the straps 20 extend across the head of a helmet wearer. For example, a first strap 20 could extend from a left rear position to a right front position, and a second strap 20 could extend from a right rear position to a left front position. However, it should be recognized that many other arrangements can be used. For example, additional straps could be provided, such as three, four, or more straps extending across the top of the wearer's head. Similarly, the locations of the connection points of the straps 20 to the rest of the helmet 1 may differ from those shown in FIG. 7 .

[0080] For example, in an arrangement where different straps 20 are adjacent to one another at the top of the wearer's head, the straps 20 may not be connected to one another, allowing some movement of one strap relative to another. In other arrangements, the straps may be connected to one another where they intersect. In a further arrangement, the head mount may include one or more straps, each extending from a connection point to the rest of the helmet 1 to a point where it connects to another strap, e.g., at a location corresponding to the top of the helmet wearer's head. Finally, as noted above, in other arrangements, the head mount may be formed from components other than straps, e.g., a cap or shell that can be fitted to the top of the head of the helmet wearer.

[0081] As shown in Figure 7, helmet 1 further includes a head-engaging device 40. Head-engaging device 40 is attached to the surface of the head mount (i.e., strap 20 in the arrangement shown in Figure 7) that faces the wearer's head when the wearer is wearing helmet 1. In other words, head-engaging device 40 is provided on the side of head mount 20 opposite the air gap that exists between head mount 20 and outer shell 2.

[0082] As discussed in more detail below, the head-engaging device 40 is mounted such that it can move relative to the head mount 20. In other words, the head-engaging device 40 and the head mount 20 are not rigidly connected to one another. The head-engaging device 40 can function in the same manner (or in a similar manner) as an interface layer, as discussed above. The ability of the head-engaging device 40 to move relative to the head mount 20 allows for movement (e.g., rotation) of the helmet 1 relative to the wearer's head in the event that the helmet 1 is subjected to an oblique impact while being worn by a wearer. This can provide the benefits discussed above, such as reducing injury to the helmet wearer from such an impact.

[0083] A low friction interface may be provided between the head mount 20 and the head engaging device 40. This may facilitate movement of the head engaging device 40 relative to the head mount 20 upon impact of the helmet 1.

[0084] The low-friction interface between the head mount 20 and the head-engaging device 40 may be implemented by any method corresponding to those discussed above with respect to other helmet arrangements. For example, the head-engaging device 40 may be formed from a material that provides a sufficiently low coefficient of friction between it and the head mount 20. For example, it may be formed from polypropylene (PP), nylon, polycarbonate (PC), polyketone, or any other low-friction material (e.g., such as those discussed above). By appropriate material selection for forming one or both of the head mount and the head-engaging device, a low-friction interface may be provided without the provision of additional components and / or surface treatments.

[0085] In other arrangements, one or both of the surfaces of the head mount 20 and the head engaging device 40 where they contact may be provided with a separate sliding facilitator (e.g., a patch of low friction material or a coating of another material), which may be another polymer with a low coefficient of friction, or a section of fabric material or felt, or may have a lubricant applied thereto.

[0086] The head engaging device 40 may be connected to the helmet 1 in any suitable manner that allows movement of the head engaging device 40 relative to the head mount 20. For example, the head engaging device 40 may be connected to the outer shell 2 by, for example, a connector that allows movement of the head engaging device 40 relative to the outer shell 2. Such a connector may include an elastic component that can stretch when movement of the head engaging device 40 relative to the outer shell 2 is required.

[0087] In some arrangements (such as that shown in FIG. 7), the head-engaging device 40 may be connected to a head mount, for example, connected to one or more straps 20 that are part of the head mount.

[0088] When the head engaging device 40 is connected to a head mount, a connector 45 may be used that allows some movement of the head engaging device 40 relative to the part of the head mount to which it is connected.

[0089] In one arrangement, the connector 45 can have first and second ends 46, 47 joined to the head-engaging device 40 at respective first and second locations on the head-engaging device 40, and positioned such that the strap 20 of the head mount is positioned between the connector 45 and the head-engaging device 40 in the region between the first and second locations on the head-engaging device 40. In such an arrangement, the strap 20 may not be rigidly secured to any part of the connector 45, allowing the strap to slide lengthwise and / or laterally relative to the connector 45. However, the head-engaging device 40 is restricted from being completely removed from the strap 20.

[0090] In such an arrangement, connector 45 may be formed from or covered by a material that provides a sufficiently low coefficient of friction between it and strap 20 so that movement of the head-engaging device relative to the head mount is not significantly reduced and therefore does not significantly interfere with the function of helmet 1. Alternatively or additionally, connector 45 may be formed from a resilient material such that, to the extent that parts of connector 45 do not slide relative to strap 20, the strap can move relative to first and second parts 46, 47 of connector 45 that are joined to head-engaging device 40, for example by stretching the connector, to allow desired movement of the head-engaging device relative to the head mount.

[0091] In an arrangement such as that shown in FIG. 7 , the connector 45 may be formed from an elongated section of material. For example, the connector 45 may be formed from a section of material in the shape of a cord, band, or tape. Such material may be, for example, generally round or rectangular in cross section. The connector may be formed from a resilient material, which may be beneficial for the function of the connector in the event of an impact to the helmet 1, as described above, and / or may facilitate assembly of the helmet 1. In one arrangement, the connector 45 may be formed from a resilient material coated with a layer of fabric. The connector 45 may alternatively or additionally be formed from silicone, rubber, or another resilient plastic material.

[0092] The connectors (such as those discussed above) may be joined to the head engaging device 40 at the first and second locations by any suitable method, including, for example, adhesive or mechanical methods (e.g., snap fit connections, etc.). Alternatively, two ends of the elongated material may be tied to each other and / or at least one end may be tied to a part of the helmet 1 to secure it.

[0093] In one arrangement, as shown generally in FIGS. 8-10 , the length of material 50 used to form connector 45 may be terminated by a component such as a relatively short bar 51. Bar 51 is connected to elongated material 50 such that the length of bar 51 is at a predetermined angle (optionally perpendicular) to the elongated length of material. As shown in FIG. 9 , during assembly, bar 51 may be inserted lengthwise through hole 41 in head engagement device 40. However, as shown in FIG. 9 , bar 51 will then naturally orient itself against the surface of head engagement device 40, preventing bar 51 from passing back through the hole. It will be appreciated that in such an arrangement, hole 41 in head engagement device 40 may be configured to be larger than the cross-section of bar 51 but smaller than the length of bar 51.

[0094] In some arrangements (such as that shown in FIG. 7 ), strap 20 is connected to head-engaging device 40 such that strap 20 is on the opposite side of head-engaging device 40 from the helmet wearer's head. Accordingly, connector 45 is also, for the most part, on the opposite side of head-engaging device 40 from the helmet wearer's head. In connector arrangements such as those discussed above and shown in FIGS. 8-10 , connector 45 may be configured such that the length of material forming connector 45 extends from the side that is in contact with strap 20 through hole 41 in head-engaging device 40, with the result that bar 51 is positioned on the surface of head-engaging device 40 that faces the helmet wearer's head.

[0095] If this is undesirable, for example if it affects the comfort of the helmet wearer, or if it is desirable to hide the bar 51 for aesthetic reasons or to reduce the risk of damage to and / or tampering with the connector 45, a second hole 41 may be provided in the head-engaging device 40 at each location used to secure a connector. In such an arrangement, a length of material can pass from the area where the connector engages the strap through one hole, across the section of the head-engaging device 40 between the two holes 41, and then through the second hole. In such an arrangement, the bar 51 is held on the same side of the head-engaging device 40 as the strap 20, i.e., on the opposite side of the head-engaging device 40 from the wearer's head.

[0096] In one arrangement, each connector 45 may be formed from its own separate section of elongated material. Alternatively, one or more connectors 45 may be formed from a single piece of section of elongated material. For example, multiple connectors 45 may be formed in a manner corresponding to that described above, but instead of a bar 51 where a connector 45 joins the head engaging device 40, the elongated material may extend to another connector 45. In one arrangement, all of the connectors 45 used to connect the head engaging device 40 to the head mount may be formed from a single length of elongated material.

[0097] In an arrangement in which the head mount includes straps 20 that extend across the helmet wearer's head between two connection points on the outer shell 2, as shown in FIG. 7, a pair of connectors 45 may be provided for each strap 20 on opposite sides of the head engagement device 40. Similarly, at least one connector 45 (optionally, a pair of connectors 45) may be provided for each strap 20. However, this is not required. For example, as shown in FIG. 11, fewer connections may be provided between the head engagement device 40 and the head mount (e.g., straps 20, etc.). In the arrangement shown in FIG. 11, for example, connectors 45 may be provided only at the rear of the helmet 1.

[0098] 12 shows an alternative arrangement for connecting the head-engaging device 40. As shown, the head-engaging device 40 can include a hole 60 through which the strap 20, which is part of the head mount, can pass.

[0099] As discussed above, other arrangements for connecting the head-engaging device 40 may alternatively or additionally be used. For example, an elastically deformable connector may be provided between the head mount and the head-engaging device 40, with a first part of the connector secured to a part of the head mount (e.g., strap 20) and a second part of the connector secured to a part of the head-engaging device 40. Movement of the head-engaging device relative to the head mount may be enabled by stretching and / or other deformation of the connector. Such a connector may be secured to one or both of the opposing surfaces of the head mount and the head-engaging device. The connector may be secured to one or both of the head mount and the head-engaging device by any suitable means (including, for example, by hook and loop material and / or adhesive).

[0100] As shown in the arrangements shown in FIGS. 7, 11, and 12, the head-engaging device 40 may be provided as a single component (e.g., a single layer of material, etc.). However, this need not be the case. For example, the head-engaging device may be formed from multiple separate sections. The separate sections may remain separate and, for example, may be separately connected to the head mount and / or other parts of the helmet 1. Alternatively, two or more sections may be connected during assembly of the helmet. In one arrangement, the separate sections of the head-engaging device may be connected to each of the straps 20 (or a subset of the straps 20) that form (or are part of) the head mount.

[0101] In one arrangement, the head-engaging device (or one or more parts thereof) may be formed by injection molding or vacuum forming, so that it may be formed to have a shape that matches the shape of the helmet wearer's head.

[0102] In configurations of helmet 1 (such as that shown in FIG. 7), the head mount can include a head ring 30 that engages at least the helmet wearer's forehead and can substantially encircle the wearer's head. It should be appreciated that such a head ring 30 can be connected to helmet 1 separately from the remainder of the head mount (e.g., straps 20, etc.). Alternatively, head ring 30 can be connected to helmet 1 by straps 20. As a further alternative, straps 20 can be connected to the remainder of helmet 1 by head ring 30.

[0103] In arrangements in which helmet 1 includes head ring 30, head engagement device 40 can include crown region 43 and forehead region 44, with crown region 43 configured to be positioned between the top of the helmet wearer's head and a head mount (e.g., strap 20, etc.), and forehead region 44 configured to be positioned adjacent head ring 30, at least in the region of the helmet wearer's forehead. Forehead region 44 of head engagement device can be positioned to slide relative to the portion of the head ring adjacent to it, in the same manner as other sections of head engagement device 40 are positioned to move relative to other sections of the head mount (e.g., strap 20, if used).

[0104] The frontal region 44 of the head engaging device may be connected to the head ring and / or outer shell 2, for example, by a connector configured to allow movement of one part relative to another, allowing movement of the frontal region 44 of the head engaging device 40 relative to the head ring 30. Alternatively or additionally, the frontal region 44 of the head engaging device 40 may be connected to the helmet 1 via an intermediate region 48 of the head engaging device 40. In particular, the intermediate region 48 of the head engaging device 40 may connect the frontal region 44 to the crown region 43. In one arrangement, the crown region 43, intermediate region 48, and frontal region 44 of the head engaging device may be integrally formed from a single plate of material.

[0105] As shown in FIG. 7 , in one arrangement, the frontal region 44 of the head-engaging device 40 can extend along the head ring 30, for example, in the form of arms 49. Thus, each arm 49 of the head-engaging device can be adjacent to, but not connected to, a side of the crown region 43 of the head-engaging device. In an optional arrangement, one or more reinforcements can be provided between each arm 49 of the head-engaging device 40 and an adjacent part of the crown region 43 of the head-engaging device. This can be provided to reduce the extent to which a gap between the crown region 43 and the arms 49 of the head-engaging device 40 increases under an impact against the helmet.

[0106] The reinforcement between the crown region 43 and the arms 49 of the head-engaging device 40 may be integrally formed with the remainder of the head-engaging device. Alternatively or additionally, the reinforcement may be provided in the form of a plate of material (e.g., formed from any of the materials discussed above for forming the head-engaging device) that is connected at each end to the crown region 43 and the arms 49 of the head-engaging device 40. The plate of material may be connected to the crown region 43 and the arms 49 of the head-engaging device 40 by any convenient means (e.g., including hook and loop connections, snap fit connections, and / or adhesives). The connectors may be adjustable so that the plate of material can be used as a reinforcement for helmets of different sizes.

[0107] The intermediate region 48 of the head-engaging device may be configured to serve additional functions beyond connecting the crown region 43 to the forehead region 44. In particular, in the event of a forward impact of the helmet 1, the intermediate region 48 can help prevent the helmet wearer's forehead from contacting the forehead region of the outer shell 2. For example, this can reduce the tendency of the front of the wearer's head to pass between the two straps 20 in some arrangements (such as that shown in FIG. 7).

[0108] It should be recognized that such an arrangement is not required. The straps 20 used to form the head mount may in any event be positioned to avoid such potential problems. For example, a sufficient number of straps 20 and / or sufficiently wide straps may avoid or minimize the problem. Alternatively or additionally, straps 20 may be provided that extend from the front of the helmet.

[0109] Alternatively or additionally, additional support for the head-engaging device may be provided, which may improve the tendency of the wearer's head (and thus the head-engaging device) to pass through the gap between the two straps and / or head ring. Such support may be provided in the form of a plate of material (e.g., formed from any of the materials discussed above for forming the head-engaging device). The support may be connected to the head ring at a location between the two straps. Such support may be provided, for example, on one or more of either side of the helmet, the front of the helmet, and the rear of the helmet. The support may be connected to the head ring by any convenient means (e.g., including hook and loop connections, snap-fit ​​connections, and / or adhesives).

[0110] 13, the crown region 43 of the head-engaging device 40 is provided on the side of the head mount (e.g., strap 20) facing the head of the wearer of the helmet 1, while the forehead region 48 may be provided on the opposite side of the head ring 30. Such an arrangement may therefore be configured such that the head ring 30 is positioned between the forehead of the helmet wearer and the forehead region 48 of the head-engaging device.

[0111] Such an arrangement may be beneficial when the head ring 30 (at least in the forehead region) is relatively soft and / or flexible. In such an arrangement, a low-friction interface between the frontal region 48 of the head engagement device 40 and the part of the head ring 30 adjacent the wearer's forehead allows movement of the head ring 30 (and thus the wearer's forehead) relative to the forward region of the outer shell 2. As shown, the frontal region 48 of the head engagement device 40 may be connected to the head ring 30 by a connector 49. Such a connector may be similar to those discussed above or another suitable form of connector that allows relative movement between the connected components.

[0112] 14 and 15, one or more pads 66, 67 may be provided on the helmet 1. For example, in any of the helmet configurations discussed above that include the forehead region 44 of the head engagement device 40, a forward pad 66 may be positioned adjacent the forehead of the helmet wearer. Depending on the configuration of the helmet 1, the forward pad may be connected to one or more of the head ring 30, the forehead region 44 of the head engagement device 40, and the outer shell 2.

[0113] For example, in an arrangement in which the frontal region 44 of the head engaging device 40 is provided between the head ring 30 and the helmet wearer's forehead, the front pad 66 may be directly connected to the frontal region 44 of the head engaging device 40. In such an arrangement, the frontal region 44 of the head engaging device 40 may include protrusions or hooks 68 that may engage with the front pad 66.

[0114] Alternatively or additionally, the front pad 66 may be connected to the head ring 30 by a resilient connector 69 that engages with a hook or protrusion 70 formed on the head ring 30. In such a configuration, the resilient connector 69 is configured to be sufficiently stretchable to allow the front pad 66 to move relative to the head ring 30.

[0115] Alternatively or additionally, the front pad 66 can include a section of fabric, optionally elastically deformable, that extends outward and around opposite sides of the head ring 30. The front pad 66 can then be connected to the head ring by, for example, a hook and loop connection, with sections of hook or loop material, respectively, provided on the fabric extension of the front pad 66 and glued to the surface of the head ring 30. Alternatively, the fabric extension of the front pad 66 can include elastic connectors that engage with hooks or protrusions formed on the head ring 30.

[0116] An arrangement in which the fabric extension of the forward pad 66 extends to the opposite side of the head ring may be preferable because it may have an improved aesthetic appearance, and the fabric covering the edges of the head ring and head-engaging device may reduce the risk of abrasion of the helmet wearer's skin against the edges. Furthermore, when the head-engaging device 40 moves relative to the head ring under impact, sections of the head ring 30 may no longer be covered by the head-engaging device. However, the fabric may be able to slide relative to the head ring 30, allowing further movement to be provided.

[0117] In arrangements where part of the head ring 30 is provided between the helmet wearer's forehead and the forehead region 48 of the head engagement device 40 (such as that shown in FIG. 13), the front pad may be connected directly to the head ring 30. Alternatively or additionally, it may be connected to the outer shell 2 and / or the forehead region 48 of the head engagement device 40 by elastic connectors.

[0118] In some arrangements, one or more pads 67 may be provided over other parts of the head engaging device 40 (e.g., over the crown region 43 of the head engaging device 40). Such pads 67 may function to improve comfort for the helmet wearer and / or to provide separation of the head engaging device 40 from the wearer's head and promote ventilation. As shown in FIG. 14, the pads 67 may be positioned, for example, so that they do not overlap where connectors 45 are provided to connect the head engaging device 40 to a head mount. Alternatively or additionally, one or more pads 67 may be positioned to cover the connectors 45.

[0119] 14, one or more holes 43 may be provided in the head-engaging device 40. Such holes may facilitate ventilation between the wearer's head and the gap 21 between the head mount 20 and the outer shell 2.

[0120] As discussed above, the head engaging device 40 can also include one or more holes 41 that are used to engage with a connector. Accordingly, it should be appreciated that the head engaging device 40 can be provided with holes that can function to either provide ventilation or to engage with a connector. Alternatively, different holes can be provided for specific functions.

[0121] It should also be appreciated that where holes 41 are provided for engagement with a connector, head engaging device 40 may be provided with holes 41 at locations necessary for engagement with a connector in order to fit head engaging device 40 into a particular helmet design. Alternatively, head engaging device 40 may be provided with multiple holes 41 positioned to allow engagement device 40 to be installed in any of multiple helmet designs and / or helmet sizes.

Claims

1. A helmet, the helmet comprising: an outer shell; a head mount configured to be worn on top of the head of a wearer of the helmet, the head mount suspended within the outer shell such that, in use, an air gap is provided between the head mount and the outer shell; a head-engaging device mounted on a surface of the head mount, the head-engaging device configured to face the head of the wearer of the helmet, the head-engaging device being provided on a side of the head mount opposite the air gap that exists between the head mount and the outer shell, and the head-engaging device being movable relative to the head mount; Including, a low-friction interface is provided between the head mount and the head-engaging device to allow movement of the head-engaging device relative to the head mount under impact of the helmet; the head-engaging device includes a plate of material formed by injection molding or vacuum forming to have a shape configured to conform to the head of the wearer of the helmet; the head engagement device is connected to the head mount only at the rear of the helmet; A helmet wherein the head-engaging device includes one or more pads provided on a surface of a crown region of the head-engaging device that faces the head of the wearer.

2. 2. The helmet of claim 1, wherein the head mount includes a plurality of straps configured to extend across the top of the head of the helmet wearer and connected to connection points on the outer shell.

3. The helmet of claim 2 , wherein the head mount includes a plurality of straps extending between opposing pairs of connection points.

4. 4. A helmet according to claim 2 or 3, wherein at least two straps are connected to each other.

5. 5. A helmet according to any one of claims 2 to 4, wherein the head engagement device is connected to the head mount by at least one connector that engages with one of the straps.

6. 6. The helmet of claim 5, wherein the at least one connector has a first end and a second end, both of which are joined to the head-engaging device at respective first and second locations on the head-engaging device; and a strap is positioned between the connector and the head-engaging device in a region between the first and second locations on the head-engaging device.

7. 7. A helmet according to claim 5 or 6, wherein the straps are not rigidly fixed to parts of the connector, but are allowed to slide relative to the connector.

8. 8. A helmet according to claim 6 or 7, wherein the connector is formed from an elongated section of material, optionally from one of a cord, a band or a tape.

9. The helmet of claim 8 , wherein a plurality of connectors are formed from separate pieces of the material.

10. The helmet of claim 8 , wherein a plurality of connectors are formed from a single piece section of the material.

11. 11. A helmet according to any one of claims 2 to 10, wherein the head mount includes at least one strap connected to a front portion of the outer shell and extending in a direction towards a rear portion of the helmet.

12. A helmet according to any one of claims 1 to 11, wherein the head engaging device is provided as a single component.

13. 12. The helmet of any one of claims 1 to 11, wherein the head engaging device is formed from a plurality of separate sections.

14. the head mount including a head ring configured to engage at least the forehead of a wearer of the helmet; 14. The helmet of claim 1, wherein the head engagement device includes a crown region and a forehead region, the crown region configured to be positioned between the top of the head of a wearer of the helmet and the head mount, and the forehead region configured to be positioned adjacent to the head ring.

15. The helmet of claim 14 , wherein the head-engaging device further includes an intermediate region connecting the crown region to the forehead region.

16. 16. A helmet according to claim 14 or 15, wherein the head engaging device, the frontal region, is positioned between the forehead of the wearer of the helmet and the head ring.

17. 16. A helmet according to claim 14 or 15, wherein the head ring is positioned between the forehead of the wearer of the helmet and the frontal region of the head-engaging device.

18. 18. A helmet according to any one of claims 14 to 17, wherein the helmet further comprises a front pad positioned adjacent the forehead of the wearer of the helmet.

19. 19. The helmet of claim 18, wherein the front padding is connected to at least one of the head ring, the forehead region of the head-engaging device, and the outer shell.

20. 20. The helmet of claim 19, wherein the front pads are connected by elastic connectors configured to allow the front pads to move relative to components to which they are connected.

21. 21. The helmet of any one of claims 1 to 20, wherein the head-engaging device includes a plurality of holes configured to provide at least one of a location for a connector to mate to the head-engaging device and ventilation.

22. 22. A helmet according to any one of claims 1 to 21, wherein the low friction interface is provided by a low coefficient of friction between the surface of the head mount and the head engaging device.

23. 23. A helmet according to any one of claims 1 to 22, wherein in the absence of an impact to the helmet, the separation between the outer shell and the head mount at a location corresponding to the top of the wearer's head provided by the air gap is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, optionally at least 40 mm.

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