GB2626329A - Impact liner system with airflow channels - Google Patents

Abstract

An impact liner system for a helmet shell, the system comprising front, middle and rear arrays of impact pads 1001, each array having at least two impact pads that are formed from a deformable material; each pad comprising an inner and outer face; the pads of at least one of the arrays comprise spacers 1009 extending from the outer face that space the pads from the interior surface of a helmet when installed to create self supporting airflow channels. The spacers may have a thickness less than the pads, and preferably taper in a direction away from the pads. Each impact pad may be connected to an adjacent pad by a flexible material 1011 such as a thermoplastic polyurethane. The spacers may be formed from the same material as the pads, which may be a polyurethane or nylon foam. Preferably there are shim pads configured for removable attachment via hook and loop material to the spacers to form a layer between the spacers and the inside of the helmet shell.

Description

Impact Liner System with Airflow Channels FIELD OF THE INVENTION The present invention relates to an impact liner system for a helmet shell, in addition to use of the same for improving airflow to the interior of a helmet. The invention further provides a helmet comprising the impact liner system of the present invention.

BACKGROUND OF THE INVENTION

A helmet is a form of personal protective equipment worn to protect the head from injury and are known to have been used since the 23m century BC. Helmets are typically formed of a hard material for the purpose of resisting impact on the user's head. The hard outer casing of the helmet is often referred to as the helmet shell. Historically, helmet shells have been constructed out of metals such as bronze or iron, with modern helmet shells being typically constructed from polymers such as polycarbonates and Kevlar. In order to further reduce any impact delivered to the user's head most helmets will include some form of impact absorbing structure on the inside of the helmet shell for contact with the user's head when the helmet is in use. This additional layer of protection prevents or minimises the transfer of energy from the hard material of the helmet shell to the user's head thus preventing or minimising injury.

Many removable impact absorbing structures are known in the art. Impact absorbing structures often take the form of an array of impact pads that conforms to the inside of the helmet shell and to the user's head. The advantage of this is to provide a good fit without leaving any gaps in the impact absorbing padding. As would be appreciated, any gaps in the impact absorbing padding would give rise to a weak spot where the helmet does not offer suitable protection. Any impact delivered to such a weak spot in the helmet risks being more directly transferred to the user's head risking injury or death. An example of a known helmet impact liner system to be installed in the interior of a helmet can be seen in granted US patent US 9516910 B2. This helmet liner system comprises a front impact pad array, a middle impact pad array, and a rear impact pad array, wherein each impact pad array comprises a plurality of impact pads, thus allowing for suitable coverage of the whole inside of the helmet shell such that an impact at any part of the exterior of the helmet may be mitigated.

The Advanced Combat Helmet (ACH) is the current model of combat helmet used by the United States military as well as that of many other nations such as Australia, South Korea, Mexico, etc. The ACH includes a set of pads consisting of a circular crown pad, four oblong/oval pads, and two trapezoidal pads, which may be utilised in various configurations, such as 5-pad, 6-pad and 7-pad configurations. The impact pads are fastened to the inside of the helmet in the desired configuration in order to provide mitigation of any impact occurring at any part of the exterior of the helmet. As would be appreciated, the snug fit of the impact pads around the head of the user is required in order to obtain sufficient protection. A helmet bearing an ill-fitting or missing impact pad may fail to sufficiently reduce impact load to the user's head. One limitation of this approach is that any gaps or missing sections of impact padding may leave areas of helmet which do not offer adequate protection, thus risking the hard helmet shell impacting the user's head.

For example, in the ACH system, removal of even one of the seven impact pads from the helmet liner system can severely compromise the impact protection properties of the helmet. Instructions on how to use the ACH system can be found in the US Army operator manual for Advanced Combat Helmets (ACH) TM 10-8470-204-10 -TECHNICAL MANUAL OPERATOR'S MANUAL FOR ADVANCED COMBAT HELMET (ACH) - la a c ual-00,- ;its-tat-Page 2 of this document states that "All seven helmet pads must bc worn during airborne operations and should bc worn during othcr high-risk operations such as air assault and rappelling/mountaineering. Failure to observe this precaution could result in serious injury or death because all seven pads provide maximum impact protection." Page 51 of this document, where alternative pad configurations are discussed also states that "For training and combat missions, Soldiers are to utilize the 7-pad configuration only. For non-training and non-combat missions (for example, parades, ceremonies, etc.) the 5-and 6-pad configurations are authorized. Failure to observe these precautions could result in serious injury or death to personnel." The hard material of the helmet shell, as well as the impact absorbing material of any impact absorbing padding also act as thermal insulators. This is particularly apparent for combat helmets as they require a solid shell construction with no vent holes. Head temperature is an important contributor to the user's comfort/discomfort. Furthermore, combat helmets such as the ACH are often used in hot climates, and users will often undergo intense physical exertion. This creates the problem of overheating the user's head. This can lead to hyperthermia which is a dangerous condition in which an individual's body temperature is elevated beyond normal due to failed or insufficient thermoregulation. A person suffering from hyperthermia may exhibit a number of different symptoms such as headaches, muscle cramps, and fatigue, as well as nausea, vomiting, and in extreme cases, fainting. As would be appreciated, tightly fitting and highly insulating combat helmets present the issue of contributing towards hyperthermia but may not be removed during situation with a high risk of head trauma, such as active combat missions.

One solution used by soldiers in the field is removal of, one or more impact pads of the ACH liner system. Thus, effectively using the ACH liner system in a 6-pad or even 5-pad configuration. On page 53 of the ACH operator's manual, it is stated that "The five-pad configuration is useful in hot climates". Figure 2 shows a diagram of the 5-pad configuration of the liner system of the ACH. As can be seen from Figure 2, the oblong/oval pads may be attached at any angle, e.g. horizontally or vertically. Page 58 of the ACH operator's manual describes how the vertical configuration from bolt to crown serves to maximise airflow for better temperature regulation.

However, as is clear from the ACH operator's manual this solution is not satisfactory as it compromises the integrity of the impact protection, leaving weak spots where an impact force could cause injury or death to the wearer. Another important consideration with helmets, such as combat helmets, and any impact absorbing system disposed therein, is the ability to withstand repeat impacts. A soldier in the field may not have the opportunity to replace a helmet after sustaining a first impact where the helmet has successfully withstood the impact and prevented injury. It is important that the helmet continues to maintain a suitable degree of impact protection in case any subsequent impact is sustained. If the degree of impact protection is severely reduced by a single impact, this leaves the wearer vulnerable to injury caused by repeat impact. A weak spot created by removal of an impact pad, such as the crown pad, from the ACH may not only compromise the integrity of the impact protection but may also compromise the helmet's ability to withstand repeat impacts.

Looking back to granted US patent US 9516910 B2, this provides the solution of air channels formed by inserts between the impact pads in order to provide cooling to the interior of the helmet shell, whilst avoiding the need to remove or adjust the impact pads and thus risking leaving weak spots in the helmet.

In use, arrays of impact pads are folded into a curved conformation which, when installed in the interior of a helmet shell and conformed to the shape of a user's head, constrict and/or close of any gaps between the impact pads thereby preventing flow of air. This problem is solved in US 9516910 B2 by the use of inserts disposed between the pads, more specifically between the vertical walls of adjacent impact pads, which define air channels when the helmet shell is installed on a user's head.

However, the inserts and/or vertical walls must have sufficient hardness in order to resist deformation and therefore can result in a loss of comfort to the wearer. Further, the presence of hard structures inside the helmet shell and within the array of impact pads creates hardpoints where a hardened structure may come into contact with the user's head. This gives rise to the risk that impact force delivered to specific points of the helmet shell could be transferred to the user's head via one of these hard points which would cause injury to the user. The prevention of the free movement of the pads also potentially reduces the impact absorbing efficiency of the pads, thereby reducing the overall protection provided by the helmet to a wearer.

In view of the above, the present inventors have sought to design a impact liner system that overcomes the problem of providing airflow to the interior of the helmet shell via self-supporting circumferential airflow channels and without the need for any additional solid structures (such as disclosed in US 9516910 B2) disposed within the self-supporting airflow channels to prevent the impact pads from collapsing into the self-supporting circumferential airflow channels, whilst simultaneously providing adequate impact protection across the whole helmet. In particular, the present inventors have invented an impact liner system for a helmet shell which is capable of allowing improved cooling airflow to the interior of the helmet shell, and provides a suitable degree of impact protection across the whole of the exterior of the helmet shell.

SUMMARY OF THE INVENTION

The inventors of the present invention have developed an impact liner system which seeks to address or ameliorates the problems discussed above.

In a first aspect, the invention provides an impact liner system for a helmet shell, configured to be installed in the interior of a helmet shell and arranged to protect the head of a wearer, the impact liner system comprising a front array of impact pads, a middle array of impact pads, and a rear array of impact pads, each of the front, middle and rear arrays comprising at least two impact pads, each impact pad comprising a deformable impact absorbing material, wherein each pad comprises an inner and an outer face, the inner face in use extending towards the head of a wearer and the outer face towards the helmet shell, and further wherein the at least two impact pads of at least one of the front, middle and rear arrays comprise spacers extending from the outer face, which when installed in the helmet space the impact pads from the helmet such that self-supporting circumferential airflow channels are defined by the area between the spacers of the impact pads and the inside of the helmet shell.

In a second aspect, the invention provides a helmet comprising a liner system as described herein.

in a third aspect, the invention provides the use of an impact liner system as described herein or a helmet as described herein for improving airflow to the interior of a helmet when in use.

The invention will now be described with reference to the following non-limiting figures BRIEF DESCRIPTION OF THE FIGURES Figure 1 is an excerpt from the operator's manual for the advanced combat helmet showing the 7-pad configuration of the array of impact pads used in the ACH.

Figure 2 is an excerpt from the operator's manual for the advanced combat helmet showing the 5-pad configuration of the array of impact pads used in the ACH used in hot climates to provide airflow to the interior of the helmet shell.

Figure 3 (centre) depicts an impact pad having a spacer extending from its outer face, installed in the interior of a helmet shell. Figure 3 (left) and (right) depict the impact pad's ability to hinge about its contact point to the interior of the helmet shell.

Figure 4 depicts bottom (left) side (centre) and top (right) views of an impact liner system of the present invention Figure 5 depicts a front and side view of a further cushioning layer which may be attached to an impact liner system of the present invention along with exemplary dimensions in mm.

Figure 6 depicts a front and side view of three continuous flexible materials for partially encapsulating the impact pads comprising spacers extending from the outer face, of an impact liner system of the present invention along with exemplary dimensions in mm. The continuous flexible materials also serve to connect the impact pads of each array to one or more adjacent impact pads of that array.

Figure 7 depicts a front and side view of the impact pads of an impact liner system of the present invention, shown separately from the spacers extending from their outer face along with exemplary dimensions in mm.

Figure 8 depicts a front and side view of the spacers extending from the outer face of the impact pads of an impact liner system of the present invention along with exemplary dimensions in mm.

Figure 9 depicts an impact liner system of the present invention (left) along with a set of shim pads (right).

Figure 10 depicts an impact liner system of the present invention with the positions of self-supporting circumferential airflow channels shown by arrows.

Figure 11 depicts an exploded view of a rear array of impact pads. DETAILED DESCRIPTION OF THE INVENTION In a first aspect, the invention provides an impact liner system for a helmet shell, configured to be installed in the interior of a helmet shell and arranged to protect the head of a wearer, the impact liner system comprising a front array of impact pads, a middle array of impact pads, and a rear array of impact pads, each of the front, middle and rear arrays comprising at least two impact pads, each impact pad comprising a deformable impact absorbing material, wherein each pad comprises an inner and an outer face, the inner face in use extending towards the head of a wearer and the outer face towards the helmet shell, and further wherein the at least two impact pads of at least one of the front, middle and rear arrays comprise spacers extending from the outer face, which when installed in the helmet space the impact pads from the helmet such that self-supporting circumferential airflow channels are defined by the area between the spacers of the impact pads and the inside of the helmet shell.

In the context of the present invention, an array of impact pads comprises a plurality of impact pads which may or may not be conjoined by an attachment to one or more adjacent impact pad of the array of impact pads A front array of impact pads is configured to be placed at the front of the head, the middle array of impact pads is configured to be placed at the top crown of the head also referred to as the crown of the head, and the rear array of impact pads is configured to be placed at the rear of the head. The combination of the front, middle and rear arrays of impact pads form an impact liner system that provides coverage and thus impact protection to the whole area of the interior of a helmet shell when used together.

An impact pad is a structure designed to absorb impact and thus in the context of the present invention to prevent the transfer of kinetic energy from the helmet shell to the user's head. An impact pad will typically absorb impact by virtue of an impact absorbing material and/or impact absorbing structures. Foam is an example of an impact absorbing material as the porous structure of foam transmits impact much less efficiently than a solid member.

In the context of the present invention, each impact pad comprises an inner and an outer face, the inner face extending towards the head of a wearer, when in use, and the outer face towards the helmet shell, when in use. At least two impact pads of at least one of the front, middle and rear arrays comprise spacers extending from the outer face. In the context of the present invention, a spacer is a structure on the impact pad which spaces the impact pad from the interior of the helmet shell, when the impact liner system is installed in the helmet. The spacer will thus form a point of contact with the interior of the helmet shell and cause the outer face of the impact pad to not contact the interior of the helmet shell at the area of the outer face of the impact pad where a spacer is not present. Preferably, each impact pad of the front, middle, and/or rear array of impact pads will comprise at least one spacer. Some impact pads may comprise more than one spacer, for example, two of three spacers. Preferably, the impact pads of the middle array of impact pads comprise a plurality of spacers, for example, two or three spacers. Spacers are shown in Figure 8 (left) and can be seen in the context of the whole impact liner system in Figure 9 (left).

When the impact liner system is installed in a helmet, the spacers will contact the interior of the helmet shell thus defining an area between the spacers of two adjacent impact pads and the interior of the helmet shell. This area between two adjacent impact pads and the interior of the helmet shell, for example, between two adjacent impact pads both on the front, middle or rear array of impact pads, defines a self-supporting circumferential airflow channel (that is the channel follows the inner circumference of the helmet shell). The airflow channel is self-supporting because, when the impact liner system is in use, the structure of the airflow channel is supported by the spacers of adjacent impact pads and interior of the helmet shell without the need for any further structures disposed within the self-supporting circumferential airflow channels to prevent the impact pads from collapsing into the self-supporting circumferential airflow channels. The gap between the spacers extending from the outer face of the impact pads is wider than the gap between the impact pads themselves thereby allowing great airflow (for example up to 10% more, preferably up to 20% more, more preferably up to 30% more and even up to 40% more or greater). In addition, in the scenario that that gap between two adjacent impact pads is closed or constricted by adjacent impact pads being pushed together or into contact with each other when the impact liner system is conformed to the curve of a user's head and interior of a helmet shell, the gap between the spacers of said adjacent impact pads will not be closed, even if the gap between the impact pads themselves is fully closed. The self-supporting circumferential airflow channels are thus reliably present between the spacers of adjacent impact pads of an array of impact pads, regardless of the specific fit of the impact liner system. The impact liner system may simultaneously conform to the specific shape of a user's head to provide maximal impact protection and/or avoid the presence of areas where protection is reduced due to pressure points, whilst simultaneously leaving self-supporting circumferential airflow channels open to provide airflow.

Preferably, the at least two impact pads of at least two arrays comprise spacers extending from the outer face, for example the front and middle arrays or middle and back arrays. More preferably, the at least two impact pads of all three of the arrays comprise spacers extending from the outer face. The advantage of the at least two impact pads of two, and preferably three adjacent arrays of impact pads comprising spacers extending from the outer face is that self-supporting circumferential airflow channels are formed between the adjacent arrays of impact pads, in addition to between the adjacent impact pads within an array of impact pads. The self-supporting circumferential airflow channels between arrays of impact pads are defined by the area between the spacers of two adjacent arrays of impact pads. These self-supporting circumferential airflow channels are formed in the same way as the self-supporting circumferential airflow channels between spacers extending from the outer face of impact pads within one of the arrays of impact pads, as described above and are also self-supporting for the same reasons. Figure 10 depicts where self-supporting circumferential airflow channels (shown by arrows) are formed by an impact liner system of the present invention, having a front (top), middle (centre) and rear (bottom) array of impact pads.

As would be appreciated, the self-supporting circumferential airflow channels would lead to the edge of the helmet shell and be in communication with the air outside of the helmet. As the air in the self-supporting circumferential airflow channels would be heated by head from the user' s head, the self-supporting circumferential airflow channels allow for the heated air to dissipate out of the helmet, and it is believed far more rapidly than known prior art systems.

The spacers extending from the outer face of the impact pad form points of contact with the interior of the helmer shell, when in use, and thus provide an area of non-contact where the spacers are absent which, when in use, will not be in contact with the interior of the helmet shell. Another advantage of using spacers extending from the outer face of the impact pad is that the area of contact between the impact pad and the interior of the helmet shell is minimised, and a two-step layered system is formed which both contribute towards allowing the impact pad to hinge about its contact point to the interior of the helmet shell. This allows the impact pad surface to self-level to the corresponding surface of the individual user's head. The structure of the impact pad with one or more spacers extending from the outer face thus allows for movement to adjust the impact pad's contact surface angle to match the users head whilst still retaining structural stability and not adversely effecting impact performance. Figure 3 illustrates an impact pad with a spacer extending from the outer face and its ability to hinge about its contact point to the interior of the helmet shell.

Preferably, the array of impact pads does not include any further structures disposed within the self-supporting circumferential airflow channels to prevent the impact pads from collapsing into the self-supporting circumferential airflow channels. By way of example further structures include scaffolds or other structures made from self-supporting materials such as described in US 9516910 B2.

As discussed above, a structure (or other scaffold) disposed within the self-supporting circumferential airflow channels to prevent the impact pads from collapsing into the self-supporting circumferential airflow channels would require sufficient hardness in order to resist deformation. The presence of hard structures inside the helmet shell and within the array of impact pads creates hardpoints where a hard structure may come into contact with the user's head. This gives rise to the risk that impact force delivered to specific points of the helmet shell could be transferred to the user's head via one of these hard points which would cause injury to the user. This is exacerbated by the small surface area of the hardpoint, potentially allowing for an impact to be delivered to the head over a small area, thus exerting a high pressure and potentially causing a laceration injury even at relatively low impact force. A structure intended to buttress an airflow channel without substantially blocking the airflow channel will likely require scaffold or frame like structure, such as top and vertical side walls, which will have a relatively low surface area.

Preferably, the spacers have a thickness which is less than the thickness of the impact pads from which they extend. More preferably, the spacers have a thickness which is from 40 % to 60% of the thickness of the impact pads from which they extend, for example 45 to 55% For example, the impact pads may have a thickness of from 6.5 mm to 10 mm and the spacers may have a thickness of from 3 mm to 5 mm, preferably the impact pads may have a thickness of from 7 mm to 9 mm and the spacers may have a thickness of from 3.5 mm to 4.5 mm.

As would be appreciated, in the context of the present invention, the term "thickness" as is applied to impact pads, spacers, and further cushioning layer refers to the dimension extending in the direction from the user's head towards the helmet shell, i.e. the dimension shown in Figure 5 (right), Figure 6 (left and right), Figure 7 (centre), and Figure 8 (right).

Figure 6 depicts three continuous flexible materials which each may form a layer around an array of impact pads (such as to partially encapsulate the impact pads) as well as forming the connection to one or more adjacent impact pads of the array such that the flexible material encompasses the array of impact pads. The flexible materials have pockets for receiving the impact pads and protrusions disposed thereon and thus take the shape/contours of the impact pads and spacers having a thickness of 4 mm. This has been found to be a particularly suitable thickness for the spacers with regard to being able to form self-supporting circumferential airflow channels, whilst maintaining maximum impact protection.

Optionally, the thicknesses of every impact pad and/or the thicknesses of the spacers extending therefrom are not the same across every impact pad in an array. Some impact pads may be thicker than other impact pads and/or some spacers may be thicker than other spacers. This is useful because different areas of the helmet shell may benefit from different stress vs strain responses of the impact liner system. Impacts at different locations of the helmet are not necessarily best absorbed by the same thickness of impact pad installed at said location in the helmet due to the changes in curvature and construction of the helmet shell in these locations.

It is therefore advantageous to provide thicker impact pads and/or thicker spacers in certain locations in the impact liner system. Of course, it is also the case that the helmet is not necessarily of uniform shape and therefore impacts on the helmet shell will transmit differently to the wearer of the helmet. Accordingly, it is important to be able to vary the properties of the pads accordingly.

Preferably, the spacers taper in a direction away from the outer face of the impact pads A tapered shape in a direction away from the outer face of the impact pads provides an even smaller area of contact between the impact pad and the interior of the helmet shell. Figure 3 illustrates an impact pad with a tapered spacer extending from its outer face. This further enhances its ability to hinge about its contact point to the interior of the helmet shell. Such tapering may also help with dispersion of impact energy.

Preferably, the impact pads of at least two of the front, middle and rear arrays, and optionally each of the front, middle and rear arrays, comprise impact pads comprising spacers extending therefrom. More preferably, each of the impact pads of the front, middle and rear arrays comprise spacers extending therefrom.

Preferably, the front, middle and/or rear array comprises at least three impact pads, and optionally at least five impact pads. More preferably, the front array of impact pads and the rear array of impact pads each comprise five impact pads, and the middle array of impact pads comprises three impact pads. However, it will be understood that the exact configuration can be chosen according to the size and shape of the helmet shell and the impact properties desired, for example four pads could be used or even six.

In the impact liner system shown in Figures 4 and 9 the middle array of impact pads (middle) comprises three impact pads, including a crown impact pad (the central impact pad) which is marked with the letter C, the front array of impact pads (top) and the rear array of impact pads (bottom) each comprise five impact pads. This five-three-five structure is also shown in Figures 4 and 9 (left) and has been found to be particularly well suited to conforming to the curvature of a user's head, particularly for use in military helmets. An array of five impact pads allows for more flexibility to better conform to the curvature of the front or rear of the head.

Where the impact liner system comprises a front array of impact pads comprising five impact pads, a middle array of impact pads comprising three impact pads, and a rear array of impact pads comprising five impact pads, and each of the impact pads of the front, middle and rear arrays comprise spacers extending therefrom, a total of twelve self-supporting circumferential airflow channels are formed between the spaces. This can be seen in Figure 10. The self-supporting circumferential airflow channels formed between spacers of adjacent impact pads within the same array of impact pads and the self-supporting circumferential airflow channels formed between spacers of adjacent arrays of impact pads cross through each other providing increased ventilation and heat dissipation.

Preferably, each impact pad is connected to at least one adjacent impact pad by a flexible material, preferably wherein the flexible material is a thermoplastic polyurethane Keeping each impact pad connected to at least one adjacent impact pad allows for more convenient storage and handling of the pads as it prevents them getting separated and lost. It also ensures that the pads are disposed at an appropriate distance from each other when installed in the interior of a helmet shell. The flexibility of the material allows for the array of impact pads to fold in order to best conform with the shape of the user's head and the interior of the helmet shell. This feature can be most clearly seen in Figure 4 (right) and Figure 9 (left), where the distinct impact pads are connected by a flexible material. As can be seen from for example, Figure 4 (right), some impact pads may be connected to only one adjacent impact pad, whereas other impact pads, for example, the crown impact pad, may be connected to more than one adjacent impact pad.

Optionally, a flexible material may form a layer around the impact pad (so as to substantially surround or encapsulate the impact pad) as well as forming the connection to one or more adjacent impact pads such that a continuous flexible material encompasses the array of impact pads. In such a design, the impact pad is contained or partially contained within the flexible material. This can be seen in Figure 11 where an exploded view of a rear array of impact pads is depicted, the impact pads and spacers extending from the outer face of the impact pads are partially contained within a layer of flexible material that also serves as the connection between adjacent impact pads. In Figure 11 the further cushioning layer is attached to the inner face of the impact pad where the impact pad is not covered by the flexible material. In Figure 10 the further cushioning layer taken together with the flexible material is fully encapsulating the impact pads and spacers extending from their outer face.

Whilst terms such as point of contact", "the outer face towards the helmet shell" and "between the inner face of the crown impact pad and the user's head" are used herein, it would be appreciated that these terms encompass the use of, for example, a flexible material encompassing the impact pad as an additional layer between the impact pad and the interior of the helmet shell or between the impact pad and the user's head.

Preferably, the impact absorbing material is a foam material, preferably a polyurethane foam material or a nylon foam material Foam materials provide a combination of properties that are ideal for impact absorption applications, enabling them to absorb and dissipate impact. Polyurethane foam material or a nylon foam material are particularly well suited to this purpose. The one or more spacers may be made of the same impact absorbing material as the impact pads from which they extend. Alternatively, the one or more spacers may be made of a different impact absorbing material than the impact pads from which they extend.

Optionally, the deformable impact absorbing material which forms each impact pad and/or the material which forms the spacers extending therefrom are not the same across every impact pad in an array. Some impact pads may comprise different material than other impact pads and/or some spacers may comprise different material than other spacers. For example, the impact absorbing properties of one impact pad may and/or spacer may differ from another impact pad and/or spacer due to the choice of material. This is to allow for better optimisation of the pad combinations.

Optionally, the densities of the deformable impact absorbing material and/or the densities of materials which form the spacers extending therefrom are not the same across every impact pad in an array. Some materials, such as foam materials or certain polymers may vary in density. The skilled person would understand that for such materials, the same species of material may exist having a different density. The material of some impact pads may have a different density to the material of other impact pads and/or the material of some spacers may comprise different material than the material of some other spacers.

This is useful because different areas of the helmet shell may benefit from different stress vs strain responses of the impact liner system. Impacts at different locations of the helmet are not necessarily best absorbed by the same material or density of material of the impact pad installed at said location in the helmet due to the changes in curvature and construction of the helmet shell in these locations. It is therefore advantageous to provide differing materials or density of material across impact pads in different locations in the impact liner system.

Certain materials may be undesirable, for example, if they are more expensive, more toxic, or are environmentally damaging. The use of different materials at different impact pads and/or spacers allows for the use of undesirable materials to be reduced. Similarly, if less dense materials can be used at some impact pads, whilst still providing suitable impact protection, this allows for the overall weight of the system to be reduced. This provides environmental advantages of reduced consumption of materials and reduced energy use during transport.

Preferably, fasteners are disposed on some or all of the spacers, preferably wherein the fasteners are hook and loop fasteners. Preferably, the fasteners are disposed on some or all of the spacers extending from the outer face of the impact pads Fasteners allow for quick and releasable attachment of the impact liner system to the interior of the helmet shell. Hook and loop fasteners are particularly well suited to quick and releasable attachment and are compatible with many commercially available helmet shells. As would be appreciated, some applications may prefer a rel easably attached impact liner system and helmet shell, whereas other applications may call for permanent attachment of the impact liner system to the helmet shell Whilst terms such as "point of contact" and "the outer face towards the helmet shell" are used herein, it would be appreciated that these terms encompass the use of, for example, a fastener such as a hook and loop fastener, as an additional layer between the impact pad and the interior of the helmet shell Preferably, the impact material forming one or more of the impact pads comprise one or more slits and/or notches within the deformable impact absorbing material, for example slits and/or notches extending from outer faces of the impact pads.

Slits or notches in the impact material allow for shear movement of the impact pad along the slit or notch, this increases flexibility of the impact pad and provides for an improved ability to conform to the specific shape of a user's head. In the context of the present invention a slit or notch may, for example, extend from the outer face of the material of the impact pad, preferably at least partially and potentially all the way from the outer face of the material of the impact pad to an inner face of the material of the impact pad. A slit refers to a narrower separation between two sections of the impact material of a pad where the adjacent sections remain in contact with each other when the impact pad is laid flat, and may be formed cutting with a blade. A notch refers to a wider separation between two sections of the impact pad material where the adjacent sections are not usually in contact with each other when the impact pad is laid flat, as may be formed if a thin portion of the impact pad was removed. Notches may, for example, V-shaped, U-shaped, or semi-circular. Figure? (left) depicts an array of impact pads bearing slits and notches. Slits can be seen in the front and rear arrays of impact pads (top and bottom) of Figure 7 (left), as well as in the zoomed in section of Figure 7 (right) Notches can be seen in the middle array of impact pads (centre) of the Figure 7 (left) Preferably, one or more of the impact pads comprises a further cushioning layer, optionally disposed on the inner face of the impact pad, and preferably wherein the further cushioning pad is made of a foam material The optimum impact absorbing material for use in an impact pad of the present invention may not necessarily be comfortable on the user's head. It may therefore be useful to provide a layer of a cushioning material on the inner face of the impact pad to provide additional comfort to the user. Foam materials such as nylon foam or polyurethane foam are particularly suitable for use in a further cushioning pad. Further cushioning pads can be seen in Figure 2 and Figure 11, and are specifically depicted in Figure 5 which shows a front view of a further cushioning layer suitable for attachment to the inner face of an impact liner system (left) and a side view of the further cushioning layer (right), along with exemplary dimensions. The thickness of the further cushioning layer may be, for example, from 1 mm to 20 mm, preferably from 2 mm to 15 mm, more preferably from 3 mm to 12 mm, even more preferably from 4 mm to 9 mm, most preferably from 5 mm to 8 mm, for example, 6 to 7 mm.

Preferably, the system further comprises one or more shim pads, configured for removable attachment to the spacers such that the one or more shim pads may form an additional layer between the spacers and the inside of the helmet shell, and preferably wherein the shim pads comprise hook and loop fasteners for removable attachment to the spacers and the inside of the helmet shell A key requirement of any helmet is the user' s perceived comfort while wearing the helmet. This is particularly important for helmets, particularly military ballistic helmets due to their weight, duration of wear etc. Military helmet shells come in fairly standard shapes, but each individual's head is different, and the impact liner system helps to conform the interior of the helmet to the user without causing discomfort Even when various shell sizes are offered to optimize end-user fit, head shapes within the size bracket vary greatly, for example a user's head may be more or less round/oval.

A shim pad is an additional layer of material, preferably an impact absorbing material, which may be placed between the outer face of the impact pad and the interior of the helmet shell in order to adjust the fit of the helmet to the user's head as required The shim pads may comprise fasteners, preferably hook and loop fasteners in order to provide better attachment to the impact pad and interior of the helmet shell. An example of a set of shim pads is depicted in Figure 9 (right) where the shim pads are shown detached from the impact liner system, and in Figure 4 (centre and right) where the shim pads are shown attached to the impact liner system.

Whilst a plurality of shim pads may be provided for use with the impact liner system, for example, Figure 9 depicts fourteen shim pads, the end user may use as many or as few shim pads is required to best adapt the fit of the helmet to their head. This means that anywhere from one to all of the shim pads may be used as required. In the context of the present invention a shim pad would be attached to the impact liner system at the spacers extending from the outer face of the impact pads. Whilst terms such as "point of contact" and "the outer face towards the helmet shell" are used herein, it would be appreciated that these terms encompass the use of, for example, a shim pad as an additional layer between the impact pad and the interior of the helmet shell.

In a second aspect, the invention provides a helmet comprising a liner system as described herein.

Preferably, the helmet is a combat helmet. The helmet may be made of a polycarbonate polymeric material, an aramid material such as Kevlar, or polyethylene, preferably ultra-high molecular weight polyethylene Preferably, the helmet has fasteners on the interior of the helmet shell suitable for attachment to the array of impact pads or impact liner system, preferably the fasteners are hook and loop fasteners.

In a third aspect, the invention provides the use of an impact liner system as described herein or a helmet as described herein for improving airflow to the interior of a helmet when in use.

Preferably the improved airflow provides cooling to the user's head.

The impact liner system of the present invention may be used for improving airflow to the interior of a helmet, preferably wherein the improved airflow provides cooling to the user's head, without loss of impact protection.

The impact liner of the present invention is useful where the use of helmets is required in hot climates and/or during strenuous physical activity. The self-supporting circumferential airflow channels of the impact liner system allow for heat to dissipate out of the space between the user's head and the inside of the helmet shell. As can be seen from Example 1, the impact liner system of the present invention still provides suitable impact protection whilst preventing the accumulation of excess heat inside the helmet shell.

Exemplary embodiments of the invention are described in further detail below and with reference to the figures described above.

Figure 1 is a diagram of the known array of impact pads used in the ACH, for comparison. The inner face of the array of impact pads can be seen in Figure 1. Seven impact pads are included, namely a circular crown pad (101), four oblong/oval pads (102), and two trapezoidal pads (103).

Figure 2 is a diagram of the known array of impact pads used in the ACH in the 5-pad configuration, for comparison. Five impact pads are included, namely a circular crown pad (201) and four oblong/oval pads (202). In this configuration the oblong/oval pads (202) can be attached horizontally (202a) or vertically (202b). The ACH operator's manual describes how the vertical configuration (202b) serves to maximise airflow for better temperature regulation.

Figure 3 illustrates how spacers (309) extending from an outer face of an impact pad (301) allow the impact pad to hinge about its contact point to the interior of a helmet shell (307) Also depicted in Figure 3 are a further cushioning layer (310) and a flexible membrane (311) that connects the impact pad (301) to one or more adjacent impact pads of the array of impact pads (not shown) Figure 4 depicts a view of the inner face of impact liner system (400) (left), a side view of the same an impact liner system (centre) and a view of the outer face of the same impact liner system (right). The impact liner system comprises a front array of impact pads (402) (top), a middle array of impact pads (404) (centre) and a rear array of impact pads (406) (bottom). All three impact pads of the middle array of impact pads comprise spacers (409). Two of the spacers (409) of the middle array of impact pads have been labelled for ease of reference. Figure 4 (centre and right) also depicts shim pads (414) fit onto the outer face of the impact pads. Each individual component of the impact liner system depicted in Figure 4 is shown in isolation in Figures 3 to 8.

Figure 5 shows a further cushioning layer (410) which may be disposed on the inner face of the arrays of impact pads. Figure 5 (left) shows a view of the inner face of the further cushioning layer (410), and Figure 5 (right) shows a side view of the further cushioning layer (410) with an exemplary dimension of the thickness, as well as a zoomed in view of the circled section of the further cushioning layer (410) for the front array of impact pads Figure 6 depicts three continuous flexible materials (411) which may each form a layer around an array of impact pads (such as to partially encapsulate the impact pads) as well as forming the connection to one or more adjacent impact pads of the array such that the flexible material (411) encompasses the array of impact pads The continuous flexible materials (411) have pockets (415) for receiving the impact pads and protrusions disposed thereon and thus take the shape/contours of the impact pads and protrusions which they are to encapsulate. Figure 6 (left) shows an outline of the cross-section of the continuous flexible materials (411) having the shape/contours of the impact pads along with spacers extending from their outer face with exemplary dimensions. Figure 6 (centre) shows a top-down view of the three continuous flexible materials (411) having pockets (415) for receiving the impact pads and spacers extending from their outer face with exemplary dimensions. Figure 6 (right) shows a side view of the continuous flexible materials (411) having the shape/contours of the impact pads along with spacers extending from their outer face with exemplary dimensions, as well as a zoomed in view of the circled section of the a flexible material (411), showing a side view of a pocket (415) for partially encapsulating an impact pad and spacer within in the flexible material (411).

Figure 7 (left) depicts the outer face of the material forming the impact pads of the impact liner system (400) of Figure 4 without the spacers. Figure 7 (centre) depicts a side on view of the material of the impact pads of the impact liner system without the spacers, along with exemplary dimensions. Figure 7 (right) depicts a zoomed in view of the circled section Figure 7 (left). Slits (412) are present in the impact pads to aid flexibility. In Figure 7 (left) the slits (412) can also be seen in some of the impact pads of the front and rear arrays of impact pads, as well as notches in the impact pads of the middle array of impact pads.

Figure 8 (left) depicts the spacers (409) which extend from the outer face of the impact pads of the impact liner system of Figure 4. Each of the impact pads comprises at least one spacer, with some impact pads comprising two, or three spacers.

Figure 9 (left) depicts the outer face of an impact liner system comprising a front array (402) of impact pads, a middle array of impact pads (404) and a rear array of impact pads (406), the impact pads comprising spacers extending from their outer face. In Figure 9 (left) some, but not all, of the spacers extending from the outer face of the impact pads have a layer of hook and loop fastener material (413) disposed thereon Figure 9 (right) depicts a set of shim pads (414) suitable for use with the impact liner system Figure 10 depicts the outer face of an impact liner system of Figure 9 along with the position of twelve self-supporting circumferential airflow channels that are formed when the impact liner system is in use. The positions of the self-supporting circumferential airflow channels are shown with arrows. As would be appreciated, there is no inherent directionality of the airflow and the directions of the arrows used in this figure are purely exemplary. When the impact liner system is in use, self-supporting circumferential airflow channels are formed between the spacers of adjacent impact pads within an array of impact pads, in this case, the adjacent impact pads of the front, middle and rear array. When the impact liner system is in use, self-supporting circumferential airflow channels are also formed between the spacers of the adjacent arrays of impact pads, in this case, between the front and middle arrays of impact pads and between the middle and rear arrays of impact pads.

Figure 11 depicts an exploded view of the rear array of impact pads shown in Figure 4. In this example the impact pads (1001) of the array of impact pads are contained within a flexible membrane (1011) which also serves to connect each impact pad (1001) to one or more adjacent impact pads (1001). The impact pads (1001) comprise a further cushioning layer (1010) disposed on the inner face of the impact pads and spacers (1009) extending from the outer face of the impact pads (1001). A layer of hook and loop fastener material (1013) is disposed on the outer face of the impact pads, outside of the flexible material, for attachment to the interior of a helmet shell.

The invention will now be described by the following non-limiting Examples. Example 1 An impact liner system of the present invention, as shown in Figure 9 (left), was tested in a blunt impact test along with a comparative known impact liner system. The blunt impact test was conducted to DTS022 ACH Impact Test R8, which follows the blunt impact test requirements in both AR/PD 10-02 and AR/PD 14-01 (purchase descriptions for "HELMET, ADVANCED COMBAT (ACH)" and "HELMET, ADVANCED COMBAT, SECOND GENERATION (ACH GEN H)" respectively). The known impact liner system is the commercially available Team Wendy -Epic Air (RTM).

The test impact liner systems were installed in the interior of a large, low cut, aramid helmet and placed on a test headform. The helmet containing the headform was dropped onto an anvil at the crown section. The peak acceleration of the test headform was measured and compared. The peak acceleration is given in Gs, along with the equivalent values in m/s2 given in brackets.

A second consecutive repeat test was performed using the same helmet and impact liner system in order to measure the reduction in impact protection that is caused by the first impact.

Table 1 Impact Liner System Blunt Impact Test Pad System Speed (m/s) Peak Acceleration (Gs) Test 1 Test 2 Team Wendy -Epic Air (RTM) 3.048 63 (617.8 m/s2) 81 (794.3 m/s2) Figure 9 3.048 76 (745.3 m/s2) 82 (804.1 m/s2) As can be seen from Table 1, both liner system provided suitable impact protection, as well as a suitable durability such that suitable impact protection was also maintained for the second blunt impact test.

As can be seen from the above results, the second tests yielded a higher peak acceleration, corresponding to a worse performance, i.e. more impact transmitted to the crown of a user's head. Without being bound to a particular theory it is presumed that worse performances observed on the second tests are caused by the damage to the helmet and/or impact liner system incurred during the first test. However, the reduction in performance in the system of the present invention was relatively much lower than that of the known prior art system, despite the ability to generate greater airflow and cooling effect.

Claims (1)

1. CLAIMS1. An impact liner system for a helmet shell, configured to be installed in the interior of a helmet shell and arranged to protect the head of a wearer, the impact liner system comprising a front array of impact pads, a middle array of impact pads, and a rear array of impact pads, each of the front, middle and rear arrays comprising at least two impact pads, each impact pad comprising a deformable impact absorbing material, wherein each pad comprises an inner and an outer face, the inner face in use extending towards the head of a wearer and the outer face towards the helmet shell, and further wherein the at least two impact pads of at least one of the front, middle and rear arrays comprise spacers extending from the outer face, which when installed in the helmet space the impact pads from the helmet such that self-supporting circumferential airflow channels are defined by the area between the spacers of the impact pads and the inside of the helmet shell 2 The liner system of Claim 1, wherein the array of impact pads does not include any further structures disposed within the circumferential self-supporting airflow channels to prevent the impact pads from collapsing into the circumferential self-supporting airflow channels.3. The liner system of any preceding claim, wherein the spacers have a thickness which is less than the thickness of the impact pads from which they extend.4. The liner system of Claim 3, wherein the spacers have a thickness which is from 40 % to 60% of the thickness of the impact pads from which they extend.5. The liner system of Claim 4, wherein the impact pads have a thickness of from 6.5 mm to 10 mm and the spacers have a thickness of from 3 mm to 5 mm, preferably wherein the impact pads have a thickness of from 7 mm to 9 mm and the spacers have a thickness of from 3.5 mm to 4.5 mm.6. The liner system of any preceding claim, wherein the spacers taper in a direction away from the outer face of the impact pads.7. The liner system of any preceding claim, wherein the impact pads of at least two of the front, middle and rear arrays, and optionally each of the front, middle and rear arrays, comprise impact pads comprising spacers extending therefrom.8. The liner system of any preceding claim, wherein the front, middle and/or rear array comprises at least three impact pads, and optionally at least five impact pads.9 The liner system of Claim 8, wherein the front array of impact pads and the rear array of impact pads each comprise five impact pads, and the middle array of impact pads comprises three impact pads.10. The liner system of Claim 8 or Claim 9, wherein each of the impact pads comprise spacers extending therefrom.11. The liner system of any preceding claim wherein each impact pad is connected to at least one adjacent impact pad by a flexible material, preferably wherein the flexible material is a thermoplastic polyurethane.12. The liner system of any preceding claim wherein the impact absorbing material is a foam material, preferably a polyurethane foam material or a nylon foam material.13. The liner system of any preceding claim, wherein the one or more spacers are made of the same impact absorbing material as the impact pads from which they extend.14 The liner system of any one of Claims 1 to 12, wherein the one or more spacers are made of a different impact absorbing material than the impact pads from which they extend The liner system of any preceding claim, wherein the thicknesses of every impact pad and/or the thicknesses of the spacers extending therefrom are not the same across every impact pad in an array.16. The liner system of any preceding claim, wherein the deformable impact absorbing material which forms each impact pad and/or the material which forms the spacers extending therefrom are not the same across every impact pad in an array.17. The liner system of Claim 16, wherein the densities of the deformable impact absorbing material and/or the densities of materials which form the spacers extending therefrom are not the same across every impact pad in an array.18. The liner system of any preceding claim, wherein fasteners are disposed on some or all of the spacers, preferably wherein the fasteners are hook and loop fasteners.19. The liner system of any preceding claim, wherein one or more of the impact pads comprise one or more slits and/or notches within the deformable impact absorbing material, for example slits and/or notches extending from outer faces of the impact pads 20. The liner system of any preceding claim wherein one or more of the impact pads comprises a further cushioning layer, optionally disposed on the inner face of the impact pad, and preferably wherein the further cushioning pad is made of a foam material.21. The liner system of any preceding claim, wherein the system further comprises one or more shim pads, configured for removable attachment to the spacers such that the one or more shim pads may form an additional layer between the spacers and the inside of the helmet shell, and preferably wherein the shim pads comprise hook and loop fasteners for removable attachment to the spacers and the inside of the helmet shell.22. A helmet comprising a liner system according to any one of Claims 1 to 21.23. Use of an impact liner system according to any one of Claims 1 to 21 or a helmet according to Claim 22 for improving airflow to the interior of a helmet when in use.24. The use of Claim 23 wherein the improved airflow provides cooling to the user's head.