Helmet structures and methods

Abstract

A helmet includes an inner layer comprising a plurality of hexagonal tubes, each hexagonal tube of the inner layer having a first end and a second end and being formed by a plurality of walls, and an outer layer comprising a plurality of hexagonal tubes, each hexagonal tube of the outer layer having a first end and a second end and being formed by a plurality of walls. A shear plane is defined between the inner layer and the outer layer. Connecting shear structures couple the inner layer to the outer layer at the shear plane, the connecting shear structures being arranged and configured to break away and permit movement of the outer layer relative to the inner layer when subject to a shear force greater than a predetermined magnitude. The thicknesses of the walls may also vary in a radial direction towards the outside of the helmet.

Description

HELMET STRUCTURES AND METHODSRELATED APPLICATION DATA

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 573,156, filed on April 2, 2024, the contents of which are incorporated herein by reference as if explicitly set forth.FIELD OF THE INVENTION

[0002] This application relates to structures and methods for use in protective equipment, including but not limited to helmets for use in recreational activities.BACKGROUND

[0003] Designers of protective equipment are often faced with many conflicting requirements and challenges. For example, helmets for sporting use are expected to be lightweight, able to withstand and absorb significant impacts of different types and directions, capable of providing air flow to the wearer's head in use, as well as a comfortable and conformable fit that can accommodate variations in the size or shape of a user's head within each specific helmet size. Considerations of style, and the limitations of existing molding techniques in Expanded Polystyrene (EPS) molding, are also relevant.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0004] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. Some non-limiting examples are illustrated in the figures of the accompanying drawings in which:

[0005] FIG. l is a view of an underside of a helmet shell according to some examples.

[0006] FIG. 2 is an external view of part of the helmet shell of FIG. 1 in an area above a user's forehead.

[0007] FIG. 3 is a perspective view of an internal honeycomb structure of the helmet shell of FIG. 1, according to some examples.

[0008] FIG. 4 shows the orientation of a finished component of the helmet shell of FIG. 1 relative to a print bed, in some examples.

[0009] FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D show four different crosssections of a component of the helmet shell of FIG. 1, as the cross sections being printed advance during the additive manufacturing.

[0010] FIG. 6 shows the reinforcement of a honeycomb structure, in which the intersections between adjacent walls have been reinforced, according to some examples.

[0011] FIG. 7 shows the reinforcement of part of a helmet shell in which the intersections between adjacent walls have been reinforced, in some examples.

[0012] FIG. 8 is a partial cross-sectional view of a helmet, according to some examples.

[0013] FIG. 9 is a partial cross-sectional view of a helmet, according to some examples.

[0014] FIG. 10 is a plan view of a slip plane between the inner layer and outer layer of the helmet of FIG. 9 if the helmet were flattened (i.e., the curvature of the helmet was ignored), according to some examples.

[0015] FIG. 11 is a perspective cross-sectional view through an outer layer of the helmet of Fig. 9, according to some examples.

[0016] FIG. 12 is a transverse cross-sectional view through one of the columns of the outer layer of the helmet of FIG. 9 and FIG. 10, according to some examples.

[0017] FIG. 13 is a perspective cross-sectional view of an energy management structure of the helmet, according to some examples.

[0018] FIG. 14 is a perspective cross-sectional view of an energy management structure of a helmet, according to some examples.

[0019] FIG. 15 is a side view of a helmet shell according to some examples.

[0020] FIG. 16 is a partial perspective view of an energy management structure of a helmet according to some examples.

[0021] FIG. 17 is a partial perspective view of an energy management structure of a helmet according to some examples.

[0022] FIG. 18 is a schematic cross-sectional side view of a helmet shell according to some examples.DETAILED DESCRIPTION

[0023] Honeycomb (hexagonal) sandwich panels are commonly used for lightweight mechanical structures. In such panels, hexagonal interior walls are enclosed by parallel sheets to form a plate-like assembly. Honeycomb sandwich panels are used where a high ratio of strength to mass is needed, and are typically available in paper, aluminum, fiberglass and advanced composite materials.

[0024] The desirable properties of sandwich panels extend to products produced by additive manufacturing. For example, total weight and specific strength are key concerns for the manufacture of custom 3D-printed sport safety helmets. For some products, holes through the structure are necessary, such as in a bicycle helmet where user comfort depends on adequate airflow. Unfortunately, any holes in a sandwich panel greatly reduces its mechanical properties by allowing crumpling in-plane.

[0025] For an additive manufactured helmet there are other problems with removing all or part of the outer panels: knife-like walls oriented perpendicular to the inside that may pose a safety risk, difficulty in some additive manufacturing processes to print walls consistently when there is no peripheral support, and a tendency to propagate cracks where inner and outer walls meet at ninety degrees. Simply making holes in the outer surfaces that are smaller than the hexagons defined by the walls of a honeycomb structure retain many of these mechanical problems.

[0026] Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0027] FIG. 1 is a view of an underside of a helmet shell 100 according to some examples. The helmet shell 100 has been additively manufactured to include exterior walls (not shown in FIG. 1) and interior walls 102, between which are provided a honeycomb structure as will be described in more detail below.

[0028] Ventilation holes 106 are provided in the walls 102. The holes 106 correspond to the walls of the honeycomb structure, allowing air flow to the user's head from the outside. The holes 106 thus form a honeycomb pattern corresponding to the interior honeycomb structure. The openings of the holes at the interior and exterior walls are reinforced by cylindrical or tubular end caps 104 formed at the upper and lower ends of the hexagons formed by the interior honeycomb structure. The transition from the walls of the honeycomb structure to the end caps 104 may be filleted to discourage crack propagation between the honeycomb structure and the end caps 104.

[0029] The reinforcement to the otherwise exposed hexagonal edges of the interior honeycomb structure provided by the end caps 104 improves printability and structural integrity without greatly hindering airflow from the exterior of the helmet shell to the user's head. The end caps 104 may have a circular, elliptical or some other cross-sectional shape.

[0030] In some examples, Fused Deposition Modelling (FDM) is used to make the helmet shell 100. Circular or elliptical shapes are advantageous to FDM because imprecision of starting and stopping filament precisely (retraction) does not weaken the end cap. Circular or elliptical end caps are tougher than planar endcaps and present rounded edges to the exterior surface instead of sharp edges. In some examples, the helmet shell 100 comprises a number of pieces that are made separately using additive manufacturing, which are then assembled into the final helmet shell 100. Additional components such as pads, straps and so forth are then added to the helmet shell to make up the final helmet.

[0031] Figure 2 is an external view of part of the helmet shell 100 in an area above a user's forehead. The exterior of the helmet shell 100 includes anexterior wall 202, which has an aperture defined therein. The underlying honeycomb structure is exposed by the aperture defined in the exterior wall 202, with end caps 104 providing reinforcement of the honeycomb structure. The holes 206 defined by the end caps 104 are coupled to the holes 106 shown in FIG. 1 by the hexagonal tubes forming the honeycomb structure.

[0032] As can be seen, the aperture defined by an edge 204 of the exterior wall 202 does not follow the end caps 104 as for the interior wall 102. This is typically done for aesthetic or other design purposes. The end caps 104 may, but typically do not continue underneath the exterior wall 202, since reinforcement of the interior honeycomb structure in that area is then provided by the exterior wall 202.

[0033] Also shown in FIG. 2 is the plane 210 of a print bed, and a direction 208 in which 3D printing proceeds as discussed below with reference to FIG. 4.

[0034] FIG. 3 is a perspective view of an internal honeycomb structure 300 of the helmet shell 100, according to some examples. FIG. 3 shows the part of the helmet shell 100 shown in FIG. 2 from another direction and with the exterior wall 202 removed. The normally hidden honeycomb walls 302 are visible, with end caps 104 provided on both top and bottom edges of the honeycomb walls 302 in areas that have ventilation through the helmet. The honeycomb walls 302 define a number of hexagonal tubes through which ventilation can be facilitated by the use of end caps 104.

[0035] FIG. 4 shows the orientation of a finished component 402 of the helmet shell 100 relative to a print bed 404 in some examples. As can be seen, the additive manufacturing of the component 402 is arranged so that two of the six honeycomb walls are, as far as possible, vertical to the print bed. This orientation minimizes the worst-case overhang of the honeycomb, in which walls of the honeycomb are horizontal to the print bed 404. This orientation is also illustrated in FIG. 1 by the print direction 208 and plane 210 of the print bed.

[0036] FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D show four different crosssections of a component of the helmet shell 100, such as the front section shown in FIG. 2 and FIG. 3, as the cross sections being printed advanceduring the additive manufacturing in direction 208. The cross sections shown are parallel to the plane 210 of the print bed and advance in the direction 208.

[0037] FIG. 5A is a cross section that cuts across honeycomb walls 302 that are vertical in FIG. 2. In FIG. 5B, continuing upwards, the vertical honeycomb walls 302 have each diverged into two angled honeycomb walls 504 on the interior of the helmet shell 100 but not the exterior. This is because the honeycomb orientation is somewhat angled relative to the plane 210 of the print bed. The end caps 502 on the interior of the helmet shell 100 are now elliptical in cross section, they are on the end of a honeycomb wall that is angled to the plane 210 of the print bed and are thus also angled, and the cross section of an angled circular cylinder or tube is an ellipse.

[0038] In FIG. 5C continuing upwards in direction 208, the end caps 502 on the interior surface are merging as two angled honeycomb walls 302 come together, until they have merged and transitioned to vertical end caps 502 on a vertical honeycomb walls 302 as shown in FIG. 5D.

[0039] FIG. 6 shows the reinforcement of a honeycomb structure 600, in which the intersections between adjacent walls 602 have been reinforced. In FIG. 6, exterior and interior end caps 104, 502 have been omitted for purposes of clarity. As shown, the intersections between adjacent walls 602 have been reinforced by cylindrical, conical or frustoconical columns 604. Cylindrical or conical reinforcement may also be used where interior walls meet the exterior.

[0040] Providing columns 604 at the intersections of walls 602 in a honeycomb structure 600 can improve the specific energy absorption of a sandwich panel including the honeycomb structure 600, or of the honeycomb structure 600 itself. Such integrated reinforcements are harder to produce by traditional sandwich panel construction, but are well suited to additive manufacturing. Such reinforcement is aesthetically and structurally well suited for combination with end caps 104 parallel to the head surface, and may be sized to be visually hidden by the end caps 104.

[0041] In the case of frustoconical columns 604, the diameter of a column adjacent to the inner surface of the helmet shell 100 and the diameter of thecolumn 604 adjacent to the outer surface of the helmet shell 100 can be varied from one column to another column around the helmet shell 100, or for different sections of the helmet shell 100, to optimize desired energy absorption and density. The end caps 104 may also be of variable diameter or not present everywhere. The diameters of end caps 104 at an exterior surface of the helmet shell 100 may but need not match the diameter of end caps 104 at the interior surface of the helmet shell 100. As before, the transition between end caps 104 and columns 604 may be filleted to reduce crack propagation.

[0042] In some examples of a bicycle helmet using a carbon-fiber reinforced polymer, the end caps 502 parallel to the scalp of a user and near the skin, and end caps 104 at the exterior surface of the helmet shell 100, have outer diameters of 2.2 - 3mm and 4mm respectively. This geometry is interpolated to form columns 604 perpendicular to the head where three or more walls come together. The surfaces may be constructed to smoothly vary between the diameters.

[0043] FIG. 7 shows the reinforcement of part of a helmet shell 700, in which the intersections between adjacent walls 702 have been reinforced, in some examples. FIG. 7 shows a part of the helmet shell 100 near the helmet exterior as seen from inside, with internal material removed to show detail. The left side of FIG. 7 is ventilated, with holes 206 to the outside, and the right side is unventilated, with the exterior wall 202 covering the internal honeycomb structure. End caps 104 are present on the top of the walls 702 in the ventilated area, but not where the exterior wall 202 is present and the walls 702 meet the exterior wall 202. Columns 704 of slightly smaller diameter than the end caps 104 can be observed wherever three walls 702 of the hexagonal structure meet.

[0044] In an FDM printer, material must be extruded on top of already extruded material to have something to which to attach. Having no material below the nozzle (called "overhang") leads to gross defects with material being placed away from where it is intended. Some of the posts 708 have a flattened side 706 to enable FDM printing with less overhang. A cylinder having a nearly horizontal axis can create such a situation, where the bottomof the cylinder is too much "printing on air". As shown in the image, the posts 708 have been adjusted to be flatter in ways that reduce overhangs. Such adjustments permit easier manufacture of the device using additive manufacturing. The alternative is to print extra material that has to be manually removed later, which adds cost and complexity.

[0045] While the flattened sides 706, which are nearly horizontal during 3D printing, are at risk for print defects, this is less so than a round column would be. That is because, for the flattened side 706, the filament is extruded along a shorter path between stable endpoints (the ends of two walls 702), whereas the extrusion for a cylindrical column having no supporting structure has to follow a relatively long elliptical cross-section far away from support.

[0046] In FIG. 7 for example, in which the print bed is located below the figure, it can be seen that the sides of the posts 708 that have flattened sides 706 are the columns that have angled walls 702 intersecting with the posts 708 from below. The columns 704 that do not have flattened sides have vertical walls 710 below the column 704, which provides support for material deposition.

[0047] FIG. 8 is a partial cross-sectional view of a helmet 800 according to some examples. The helmet 800 has been manufactured using one or more of the techniques described above, and includes an energy management layer 802 formed from a honeycomb structure 804. As before, the honeycomb structure 804 includes honeycomb walls 806 terminating in end caps 808 at the respective inner and outer sides of the energy management layer 802. In some examples, the honeycomb structure 804 is selectively closed on the interior and / or exterior of the energy management layer 802 by surface walls 812, to provide airflow and ventilation management or mounting points for accessories (e.g. straps, padding or rear adjuster mechanisms).

[0048] In the example illustrated in FIG. 8, the end caps 808 comprise hollow tubes. The end. caps 808 serve to stiffen the exterior and interior of the energy management layer 802 and to spread impact loads across the honeycomb structure 804. The end caps 808 are hollow to compress and absorb impact energy.

[0049] As before, columns 814 (or trabecula) are located at the intersections of the honeycomb walls 806 to strengthen the interface between adjacent honeycomb walls 806, to provide additional rigidity, and to improve impact and overall performance for a certain helmet weight, specifically to provide a better energy absorption per weight ratio. Upper portions of the honeycomb walls 806 adjacent to the exterior surface of the energy management layer 802 are formed from two separate walls, to provide double walls 810. This feature reinforces the exterior of the energy management layer 802 and works with the external end caps 808 to spread loads and impacts across the honeycomb structure 804. It also provides more efficient material usage by placing material where it is needed, saving weight by eliminating the double walls towards the interior of the hex structure where it is not needed.

[0050] The energy management layer 802 provides efficient crumpling in linear impacts and shears to absorb oblique impacts.

[0051] FIG. 9 is a partial cross-sectional view of a helmet 900 according to some examples. The helmet 900 has been manufactured using one or more of the techniques described above, and includes an energy management layer 902 formed from two honeycomb structures formed as an inner layer 904 and an outer layer 906 are separated by a slip plane 908.

[0052] The inner layer 904 includes inner layer honeycomb walls 910 that terminate in internal end caps 914 at the inner side of the energy management layer 902. The inner layer honeycomb walls 910 have a bead of material formed thereon along the edges where the walls 910 terminate at the slip plane 908. The outer layer 906 includes outer layer honeycomb walls 912 that terminate in external end caps 916 at the outer side of the energy management layer 902. The outer layer honeycomb walls 912 also have a bead of material formed thereon along the edges where the walls 912 terminate at the slip plane 908. Except where joined as described in FIG. 10, a small gap is provided between the inner layer 904 and outer layer 906 at the slip plane 908.

[0053] The beads formed along the edges of the honeycomb walls 910 and honeycomb walls 912 at the slip plane 908 facilitate relative movementbetween the inner layer 904 and outer layer 906 once the two layers have broken away from each other as described in more detail below. Otherwise, sharp or jagged edges of the honeycomb walls 910, 912 that might remain from a fabrication process such as additive manufacturing, could dig into each other or otherwise interact to provide unintended resistance to movement between the inner layer 904 and outer layer 906 after breakaway.

[0054] In some examples, the honeycomb walls 912 of the outer layer are formed as two separate layers. The honeycomb walls 912 are thus doublelayered or double-walled. This feature reinforces the outer layer 906 of the energy management layer 902 and works with the external end caps 916 to spread loads and impacts across the energy management layer 902. It also provides more efficient material usage by placing material where it is needed and saving weight by eliminating the double walls in the inner layer 904 where it is not needed.

[0055] In the example illustrated in FIG. 9, the external end caps 916 comprise hollow tubes. The external end caps 916 serve to stiffen the outer layer 906 of the energy management layer 902 and to spread impact loads across the energy management layer 902. The external end caps 916 are hollow to compress and absorb impact energy. In some examples the internal end caps 914 are also formed as hollow tubes. In some examples, the external end caps 916 are larger than the internal end caps 914 to provide additional rigidity to the external end caps 916 and thus to the outer layer 906.

[0056] As before, columns (or trabecula) are located at the intersections of the honeycomb walls 910 and at the intersections of the honeycomb walls 912 to strengthen the interface between adjacent honeycomb walls 910, 912, to provide additional rigidity, and to improve impact and overall performance for a certain helmet weight. Columns 918 between the honeycomb walls 912 of the outer layer 906 are larger than columns 920 between the honeycomb walls 910 of the inner layer 904, in some examples.

[0057] The more rigid outer layer 906 addresses high-velocity impacts or impacts with a blunt object (as opposed to a flat surface), and the less rigid inner layer 904 crumples more to absorb low-velocity impacts.

[0058] As can be seen in FIG. 9, the slip plane 908 is generally located at the midpoint of the energy management layer 902, although this can be adjusted based on design preferences. In some examples, the inner layer 904 is tapered more aggressively than the outer layer 906 as the two layers meet at the periphery 922 of the helmet. The thickness of the outer layer 906 is thus maintained for longer than the thickness of the inner layer 904 as the two layers meet at the periphery 922 of the helmet 900.

[0059] The outer layer 906 and the inner layer 904 are coupled together where they meet at the slip plane 908 by a series of connecting shear structures that are designed and configured to give way at a certain shear force between the outer layer 906 and inner layer 904 as described in more detail below. The connecting shear structures are tested so that they absorb the optimal energy for oblique impacts to the helmet and then break away when subject to a shear force greater than a predetermined magnitude, allowing the outer layer 906 and inner outer layer 906 then to move independently of one another.

[0060] This arrangement has benefits over the known MIPS (Multidirectional Impact Protection System), which consists of a low-friction layer inside a helmet against the user's head, which allows the rest of the helmet to slide relative to the head. Firstly, the slip plane 908 plane, and thus its behavior, is built into the helmet 900, distinct from and separate from the direct interface between the helmet 900 and the user's head. This permits the outer layer 906 of the energy management layer 902 to move relative to the inner layer 904 even when the inner layer 904 stops or is prevented from rotating. Also, the MIPS system provides very little initial resistance to rotation of the helmet on the user's head. The connecting shear structures, on the other hand, provide initial resistance to rotation of the outer layer 906 relative to the inner layer 904, providing initial absorption of shear forces before and during breakaway of the connecting shear structures, unlike the MIPS system which tends to provide little resistance to initial rotation. The amount of energy required to activate (shear) the slip plane can be adjusted by varying how well the slip planes are bonded to each other (i.e., more or less material). The functioning of the slip plane 908 also compliments the natural movement of a helmet on a user's head that occurs due to thepresence of hair, sweat, and so forth. This natural movement is similar to the movement provided by the MIPS system, and the energy management layer 902 thus provides complimentary movement to this natural head movement.

[0061] In some examples, the energy management layer 902 is additively manufactured / 3D printed from a single material as a monolithic structure, which also has advantages over the prior MIPS system, which is assembled from several parts of disparate materials. In other examples, sections of an energy management layer comprising both an upper and a lower layer with a slip plane therebetween, are additively manufactured / 3D printed from a single material as monolithic structures, which sections can then be assembled into a helmet.

[0062] FIG. 10 is a plan view of part of a slip plane 908 between inner layer 904 and outer layer 906 of a helmet 900 if the helmet were flattened (i.e., the curvature of the helmet was ignored), according to some examples. A layer 1000, which could either be the inner layer 904 or the outer layer 906 is seen to comprise a honeycomb structure formed of walls 1004 as before. The open ends of the honeycomb structure comprise a bead 1002 that is formed along the edges of the walls 1004 adjacent to the slip plane 908, to facilitate movement between the inner layer 904 and outer layer 906 after breakaway as discussed above.

[0063] The inner layer 904 is coupled to the outer layer 906 at the intersections of their respective honeycomb walls 910, 912 by means of connecting shear structures 1006 that are designed and configured to give way at a certain shear force between the outer layer 906 and inner layer 904. In some examples, the connecting shear structures 1006 are formed as flat discs aligned with the slip plane 908 and coupled to both the inner layer 904 and outer layer at the intersections of the honeycomb walls. In some examples, the connecting shear structures 1006 are discs or posts formed during additive manufacturing of the energy management layer 902, having a diameter of approximately 1 mm and a height of approximately 0.6 mm. The diameter of such discs will vary with the density of the hexagonal structures forming the inner layer 904 and outer layer 906, with a larger disc diameter if the hexagonal structure is less dense and a smaller disc diameter if thehexagonal structure is denser, to account for the number of interconnections between the inner layer 904 and outer layer 906 also varying with the density of the hexagonal structure.

[0064] Various alternatives are possible for the connecting shear structures 1006. In some examples, the connecting shear structures 1006 are formed as a transition between the columns 918 of the inner layer 904 and the columns 918 of the outer layer 906, with an appropriate taper between the inner layer 904 and outer layer 906, and optionally an increase or decrease in diameter at the taper or transition between the inner layer 904 and the outer layer 906, depending on the density of the hexagonal structure, to provide the intended and required breakaway resistance. In other examples, shear pins or other supplementary structures may be provided to join the outer layer 906 to the inner layer 904.

[0065] FIG. 11 is a perspective cross-sectional view through an outer layer 906 of the helmet 900, according to some examples. FIG. 11 illustrates that the hexagonal structures in the outer layer 906 are formed from two walls 1102, to provide the double walled structure described above. Also visible in FIG. 11 are the columns 918 formed where the walls 1004 of adjacent hexagonal structures meet. As can be seen, the columns 918 are not exactly cylindrical but provide a radiused fillet between adjacent hexagonal structures as illustrated in Fig. 12. Also visible is the slip plane 908 and connecting shear structures 1006.

[0066] FIG. 12 is a transverse cross-sectional view through one of the columns 918 of the outer layer 906 of the helmet 900 of FIG. 9 and FIG. 10, according to some examples. As can be seen, column 918 is defined by the meeting of three walls 1004, which together form a double wall between adjacent hexagonal structures in the outer layer 906. Rather than abrupt transitions where the walls meet, minimum-radius fillets 1202 are provided. In some examples, the columns 918 are hollow, while in other examples they are filled with material to provide additional structural rigidity.

[0067] FIG. 13 is a perspective cross-sectional view of an energy management structure 1300 of a helmet, according to some examples. In this example, a slip plane is provided between an upper layer and a lower layerof the energy management structure 1300 by providing gaps 1302 or voids between the layers along the intersection 1304 of the walls 1306 forming the honeycomb structures.

[0068] The upper layer and lower layer are thus interconnected by portions of the walls 1306 of the honeycomb structures between the gaps 1302 and not by a column or post at the intersections of the walls 1306 along the slip plane. The walls 1306 can thus give way under shear loads without support at the intersections 1304 of the walls at the slip plane. Providing gaps or holes in the walls 1306 in this manner provides lines of weakness along / around the walls of each hexagonal structure. In the illustrated embodiment, the gaps 1302 are elliptical in shape, although it will be appreciated that other shapes, configurations, sizes and locations of gaps can be provided in the walls 1306 along the slip plane to provide appropriate shear behavior.

[0069] In some examples, the end caps 1308 formed at the outer side of the energy management structure 1300 have additional structures defined therein or formed thereon to engage the outer walls 102. As seen in FIG. 13, these can comprise grooves 1310 that are arranged to receive an inward-facing lip formed on an outer shell or wall 102. As seen in FIG. 15, these structures can also comprise outwardly-extending pins 1506 to engage corresponding holes in an outer shell or wall 102 to facilitate coupling and mounting of the wall 102 to the energy management structure 1300. The grooves 1310 in adjacent end caps 1308 are aligned with each other as appropriate to jointly define a groove corresponding to the lip of the wall 102.

[0070] FIG. 14 is a perspective cross-sectional view of an energy management structure 1400 of a helmet according to some examples. In this example, a slip plane is also provided between an upper layer and a lower layer of the energy management structure 1400 by providing gaps 1402 or voids between the layers along the intersection 1404 of the walls 1406 forming the honeycomb structures.

[0071] The upper layer and lower layer are thus interconnected by portions of the walls 1406 of the honeycomb structures between the gaps 1402 and not by a column or post at the intersections of the walls 1406 along the slipplane. The walls 1406 can thus give way under shear loads without support at the intersections 1404 of the walls at the slip plane. Providing gaps or holes in the walls 1406 in this manner provides lines of weakness along / around the walls of each hexagonal structure. In the illustrated embodiment, the gaps 1402 are elliptical in shape, although it will be appreciated that other shapes, configurations, sizes and locations of gaps can be provided in the walls 1406 along the slip plane to provide appropriate shear behavior.

[0072] FIG. 15 is a side view of a helmet shell 1500 according to some examples. The helmet shell 1500 has been additively manufactured as described herein. The helmet shell 1500 comprises a honeycomb structure defined by walls 1502 and end caps 1504 as before.

[0073] As can be seen, the thickness of the helmet shell 1500 (that is, the distance or offset between the inner surface of the helmet shell 1500 adjacent to the user's head and the outer surface away from the user's head) varies around the user's head (see also FIG. 1) with, for example, the helmet shell 1500 being thicker at a back side 1508 than the side of the helmet shell 1500 above the user's ear. Various factors can explain this difference. For example aerodynamic considerations may partly define the shape of the overall helmet, in particular the thicker back side 1508 where air passing over the helmet leaves the helmet.

[0074] Adding thickness to the helmet in this manner adds weight where it may not be needed or beneficial for impact absorption and may result in the helmet being overengineered. To address this, the thickness of the double walls forming the hexagonal structure, or the presence of double walls, varies within the helmet with the distance of the outward offset from the user's head, with the walls getting narrower (tapering) as the offset from the user's head increases.

[0075] In some examples, the total width of the double walls (as described above with reference to FIG. 12) taken together varies from about 10 mm to 3 mm in an outward direction, depending on the location around the user's head and the amount of offset from the user's head of the relevant portion of the helmet. Doing this for example at the back side 1508 of the helmet shell1500 not only reduces the overall weight of the helmet but it has the added benefit of improving crumpling of the back side 1508 of the helmet shell 1500 so that oblique impacts to the rear of the helmet have a reduced torque to the user's head.

[0076] In some examples, in addition to the overall thickness of the double walls tapering as a function of distance from the head (or offset), the thickness of each of the walls themselves tapers in an outward direction, for example from approximately 1mm to approximately 0.4mm. Additionally or alternatively, the double walls can converge into a single wall as the offset from the user's head increases.

[0077] Still further, in some examples, a single wall is provided that tapers from approximately 1 mm nearer to the head to approximately 0.4mm further from the head.

[0078] In all cases, a double-walled region may be provided adjacent to the user's head or adjacent to the outer side of the helmet shell 1500. For example, a double-walled outer layer (see the double wall 810 in FIG. 8) can provide impact resistance while the underlying tapering single or double walls provide impact absorption by crumpling more easily.

[0079] FIG. 16 is a partial perspective view of an energy management structure of a helmet according to some examples. In this example, double walls 1602 can be seen at the outer side of the energy management structure 1600. In this example, the double walls 1602 are tapered from the inner side of the energy management structure 1700 adjacent to the user's head to the outer side of the energy management structure 1600.

[0080] FIG. 17 is a partial perspective view of an energy management structure of a helmet according to some examples. In this example, single walls 1702 can be seen at the outer side of the energy management structure 1700. In this example, the single walls 1702 at the outer side of the energy management structure 1700 have either themselves tapered from the inner side of the energy management structure 1700 adjacent to the user's head to the outer side of the energy management structure 1600, or are the result of double walls closer to the user's head merging as the distance from the user's head increases, or some combination of the above.

[0081] FIG. 18 is a schematic cross-sectional side view of a helmet shell 1800 according to some examples. FIG. 18 is not to scale. The helmet shell 1800 has been additively manufactured as described herein. The helmet shell 1800 comprises a honeycomb structure defined by walls between inner end caps 1802 and outer end caps 1804 as before, and includes a slip plane 1806 and interconnecting structures as described above.

[0082] As can be seen, the thickness of the helmet shell 1800 (that is, the distance or offset between the inner end caps 1802 of the helmet shell 1800 adjacent to the user's head and the outer end caps 1804 away from the user's head) varies around the user's head 1808. As specifically illustrated in the example shown in FIG. 18 the helmet shell 1800 is thicker (the offset is greater) at a back side 1810 than the top side 1812 of the helmet shell 1800. Various factors can explain this difference. For example, aerodynamic considerations may partly define the shape of the overall helmet, in particular, the thicker back side 1810 where air passing over the helmet leaves the helmet.

[0083] Adding thickness (offset) to the helmet in this manner adds weight where it may not be needed or beneficial for impact absorption and may result in the helmet being overengineered. To address this, the thicknesses of the walls forming the hexagonal structure vary within the helmet as the offset varies around the user's head, with the walls generally getting thinner as the total offset increases. Areas of differing wall thickness are also provided along the walls in a radial direction, to provide different functions.

[0084] As illustrated schematically in FIG. 18, in some examples, provided is a high-energy impact wall 1816 at the top side 1812, with a crumple zone wall 1820 at a back side 1810 of the helmet, with transitional walls 1818 provided between the high-energy impact walls 1816 and the crumple zone walls 1820.

[0085] The high-energy impact walls 1816 include a thicker portion 1826 further from the user's head 1808 and a thinner portion 1828 closer to the user's head 1808. In the illustrated example, the thicker portion 1826 is above the slip plane 1806 and the thinner portion 1828 is below the slip plane 1806. The thicker portions 1826 are intended to resist high-energyimpacts and to prevent object penetration, while the thinner portions 1828 are intended to crumple to absorb impact energy. Together, the thicker portions 1826 form a high-energy impact layer within the helmet, while the thinner portions 1828 form a high-energy crumple zone.

[0086] As the offset between the outer end caps 1804 and the inner end caps 1802 increases from the top side 1812 of the helmet shell 1800 to the back side 1810, in what can be described as an increasing offset zone 1822, the length in a radial direction of thicker portion 1826 of the walls decreases, until there is no thicker portion present, for example in crumple zone wall 1820. Transitional walls 1818 are located between high-energy impact wall 1816 and crumple zone wall 1820 in the increasing offset zone 1822, in which the radial extent of the thicker portion 1826 decreases progressively.

[0087] In the illustrated examples, as the radial extent of the thicker portion 1826 decreases in the increasing offset zone 1822 and the radial extent of the thinner portion 1828 increases, an additional thinner portion 1828 is provided between the thicker portion 1826 and the outer end cap 1804, although it will be appreciated that additional thinner portions could also be provided between the thicker portion 1826 and the slip plane 1806.

[0088] Moving from the top side 1812 to the front side 1814 of the helmet, the offset initially remains constant in a constant offset zone 1824. As can be seen in this zone, the lengths (radial extents) of the thicker portions 1826 and the thinner portions 1828 remain constant, in some examples in an approximately one-to-one ratio.

[0089] In some examples, the thicker portions 1826 are approximately 0.8 to 1 mm thick, while the thinner portions 1828 are approximately 0.4mm, again in an approximately one-to-one ratio. While step changes between are illustrated between the thinner portions 1828 and the thicker portions 1826 in the schematic view illustrated in FIG. 18, it will be appreciated that the wall thicknesses can taper from one thickness to another in some examples. Additionally, while the thicker portions 1826 are illustrated as being above the slip plane 1806 in FIG. 18, in some examples the thicker portions 1826 are provided below the slip plane 1806 while the thinner portion 1828 areprovided above the slip plane 1806 in the high-energy impact walls 1816 and / or in the transitional walls 1818.

[0090] Various examples are contemplated.

[0091] Example l is a helmet, comprising: an inner layer comprising a plurality of hexagonal tubes, each hexagonal tube of the inner layer having a first end and a second end and being formed by a plurality of walls; an outer layer comprising a plurality of hexagonal tubes, each hexagonal tube of the outer layer having a first end and a second end and being formed by a plurality of walls, the inner layer being located inside the outer layer with a shear plane defined between the inner layer and the outer layer; and connecting shear structures coupling the inner layer to the outer layer at the shear plane, the connecting shear structures being arranged and configured to break away and permit movement of the outer layer relative to the inner layer when subject to a shear force greater than a predetermined magnitude.

[0092] In Example 2, the subject matter of Example 1 includes, wherein connecting shear structures comprise discs located at intersections of the plurality of walls forming the inner layer and outer layer.

[0093] In Example 3, the subject matter of Examples 1-2 includes, wherein edges of the hexagonal tubes of the inner layer and edges of the hexagonal tubes of the outer layer adjacent to the shear plane have beads formed thereon.

[0094] In Example 4, the subject matter of Examples 1-3 includes, wherein the inner layer and the outer layer have approximately the same thickness.

[0095] In Example 5, the subject matter of Example 4 includes, wherein the thickness of the inner layer tapers more quickly than the thickness of the outer layer where the inner and outer layer meet at a periphery of the helmet.

[0096] In Example 6, the subject matter of Examples 1-5 includes, end caps located at outer ends of the hexagonal tubes of the outer layer.

[0097] In Example 7, the subject matter of Example 6 includes, wherein the end caps comprise hollow tubes.

[0098] In Example 8, the subject matter of Examples 1-7 includes, end caps located at inner ends of the hexagonal tubes of the inner layer.

[0099] In Example 9, the subject matter of Examples 1-8 includes, supporting columns along the hexagonal tubes of the inner and outer layers where the walls of adjacent hexagonal tubes meet.

[0100] In Example 10, the subject matter of Examples 1-9 includes, wherein the plurality of hexagonal tubes forming the outer layer are formed of double walls.

[0101] In Example 11, the subject matter of Example 10 includes, wherein a total thickness of the double walls varies with distance from a user's head.

[0102] In Example 12, the subject matter of Examples 1-11 includes, wherein the plurality of hexagonal tubes forming the outer layer are formed of single walls.

[0103] In Example 13, the subject matter of Examples 1-12 includes, wherein at least some of the walls in the outer layer comprise relatively thicker portions and at least some of the walls in the inner layer comprise relatively thinner portions.

[0104] In Example 14, the subject matter of Example 13 includes, wherein at least some of the walls in both the inner layer and the outer layer of the helmet comprise only relatively thinner portions.

[0105] In Example 15, the subject matter of Examples 13-14 includes, wherein the walls in both the inner layer and the outer layer of the helmet that comprise only relatively thinner portions are located at a back side of the helmet.

[0106] Example 16 is a helmet, comprising: an energy management layer comprising a plurality of hexagonal tubes, each hexagonal tube having a first end and a second end and being formed by a plurality of walls, the first ends in use being located closer to a user's head and the second ends being located in use further from the user's head, wherein; at least some of the walls of some of the hexagonal tubes, including a relatively thicker portion at the first ends and a relatively thinner portion at the second ends.

[0107] In Example 17, the subject matter of Example 16 includes, wherein other walls of the hexagonal tubes include only relatively thinner portions.

[0108] In Example 18, the subject matter of Example 17 includes, wherein the hexagonal tubes including only relatively thinner portions are located at a back side of the helmet.

[0109] In Example 19, the subject matter of Examples 16-18 includes, wherein the energy management layer comprises an outer layer and an inner layer separated by a slip plane.

[0110] In Example 20, the subject matter of Example 19 includes, wherein the relatively thicker portions are located in the outer layer.

[0111] Example 21 is an apparatus comprising means to implement of any of Examples 1-20. Example 22 is a system to implement of any of Examples 1-20. Example 23 is a method to implement of any of Examples 1-20.

Claims

CLAIMSWhat is claimed is:

1. A helmet, comprising: an inner layer comprising a plurality of hexagonal tubes, each hexagonal tube of the inner layer having a first end and a second end and being formed by a plurality of walls; an outer layer comprising a plurality of hexagonal tubes, each hexagonal tube of the outer layer having a first end and a second end and being formed by a plurality of walls, the inner layer being located inside the outer layer with a shear plane defined between the inner layer and the outer layer; and connecting shear structures coupling the inner layer to the outer layer at the shear plane, the connecting shear structures being arranged and configured to break away and permit movement of the outer layer relative to the inner layer when subject to a shear force greater than a predetermined magnitude.

2. The helmet of claim 1, wherein connecting shear structures comprise discs located at intersections of the plurality of walls forming the inner layer and outer layer.

3. The helmet of claim 1, wherein edges of the hexagonal tubes of the inner layer and edges of the hexagonal tubes of the outer layer adjacent to the shear plane have beads formed thereon.

4. The helmet of claim 1, wherein the inner layer and the outer layer have approximately the same thickness.

5. The helmet of claim 4, wherein the thickness of the inner layer tapers more quickly than the thickness of the outer layer where the inner and outer layer meet at a periphery of the helmet.

6. The helmet of claim 1, further comprising end caps located at outer ends of the hexagonal tubes of the outer layer.

7. The helmet of claim 6, wherein the end caps comprise hollow tubes.

8. The helmet of claim 1, further comprising end caps located at inner ends of the hexagonal tubes of the inner layer.

9. The helmet of claim 1, further comprising supporting columns along the hexagonal tubes of the inner and outer layers where the walls of adjacent hexagonal tubes meet.

10. The helmet of claim 1, wherein the plurality of hexagonal tubes forming the outer layer are formed of double walls.

11. The helmet of claim 10, wherein a total thickness of the double walls varies with distance from a user's head.

12. The helmet of claim 1, wherein the plurality of hexagonal tubes forming the outer layer are formed of single walls.

13. The helmet of claim 1, wherein at least some of the walls in the outer layer comprise relatively thicker portions and at least some of the walls in the inner layer comprise relatively thinner portions.

14. The helmet of claim 13, wherein at least some of the walls in both the inner layer and the outer layer of the helmet comprise only relatively thinner portions.

15. The helmet of claim 13, wherein the walls in both the inner layer and the outer layer of the helmet that comprise only relatively thinner portions are located at a back side of the helmet.

16. A helmet, comprising: an energy management layer comprising a plurality of hexagonal tubes, each hexagonal tube having a first end and a second end and being formed by a plurality of walls, the first ends in use being located closer to a user's head and the second ends being located in use further from the user's head, wherein;at least some of the walls of some of the hexagonal tubes, including a relatively thicker portion at the first ends and a relatively thinner portion at the second ends.

17. The helmet of claim 16, wherein other walls of the hexagonal tubes include only relatively thinner portions.

18. The helmet of claim 17, wherein the hexagonal tubes including only relatively thinner portions are located at a back side of the helmet.

19. The helmet of claim 16, wherein the energy management layer comprises an outer layer and an inner layer separated by a slip plane.

20. The helmet of claim 19, wherein the relatively thicker portions are located in the outer layer.

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