WO2024189393A1 - Helmet - Google Patents

Abstract

Helmet (1) comprising: at least a cellular energy‐absorbing insert (2); a foam liner (3) comprising at least one recess (4) shaped to accommodate the at least one cellular energy‐absorbing insert (2); the foam liner (3) also comprises one or more air vents (6) for allowing an air transit from outside the helmet (1) to the cellular energy‐absorbing insert (2); wherein the cellular energy‐absorbing insert (2) comprises one or more cut‐outs (5) provided in correspondence of said one or more vents (6).

Description

TITLE

HELMET

DESCRIPTION

TECHNICAL FIELD

[0001] The present invention relates to the field of helmets with cellular energy-absorbing structures. In particular, the present invention relates to helmets using layered structures.

BACKGROUND ART

[0002] In the state of the art some helmet solutions using cellular energy-absorbing structures are known. These kinds of structures have excellent properties in terms of impact energy absorption with respect to traditional polymeric foam materials. Despite this, the foam allows to obtain fascinating shapes and is still easier to mould with respect to the cellular structures. Therefore, many solutions employing these kinds of energy-absorbing structures combine the use of foam liners and cellular structures.

[0003] An example in this sense is disclosed in the patent US10834987. This document relates to a helmet comprising a plurality of cellular liners that are retained within respective recesses of a polymer foam shell without the necessity of using additional fasteners or adhesive. Substantially, the cellular liner of this document is sized to fit snug within the recess. Despite the cellular liner being retained in the foam shell, during an oblique impact to the helmet, the cellular liner tends to slide over a barrier layer attached to the polymer shell and simultaneously it in-plane compresses. When the cellular liner crosses an air vent of the foam liner, the cells of the cellular liner tend to enter inside it and to get stuck into the vent, thus increasing the risk of a brain torque in the wearer. Indeed, the sliding of the cellular liner can abruptly interrupt, with serious implications in term of safety for the wearer.

[0004] The patent EP3473122B1 partially solves this problem through vent openings that are chamfered to allow an energy absorbing insert in a cycling helmet to not stop in a vent opening and to slide with a limited restriction.

[0005] The patent US10736373B2 describes how the vents, in a helmet comprising a foam liner and cellular inserts, can be arranged with respect to the recesses in which the cellular inserts are retained. This document does not refer to the interaction between vent and cellular insert during an impact. SUMMARY

[0006] Said and other drawbacks of the state of the art are now solved by a helmet comprising at least a cellular energy-absorbing insert, a foam liner comprising at least one recess shaped to accommodate the at least one cellular energy-absorbing insert. The foam liner also comprises one or more vents for allowing an air transit from outside the helmet to the cellular energy-absorbing insert. The cellular energy-absorbing insert comprises one or more cut-outs provided in correspondence of said one or more vents. The cellular energy-absorbing insert so conceived avoids that certain cells of the cellular insert enter and get stuck into a vent of the foam liner during an impact. The cut-out of the cellular energy-absorbing insert allows an in-plane deformation of the cellular insert without an interaction between its cells and the vent. Moreover, these cut-outs improve the ventilation of the helmet.

[0007] Preferably, each cut-out can be centred on the corresponding vent. This arrangement of the cut-out/s allow to guarantee a margin between the hole of the vent and the hole of the cut-out.

[0008] Advantageously, the helmet can comprise a protective layer attached to the foam liner in correspondence of bottom/s of said recess/es. The protecting layer contributes to facilitate the relative sliding of cellular energy-absorbing insert over the foam liner and to prevent the cellular energy-absorbing insert to sink in the foam liner.

[0009] In particular, the protective layer can be also attached to sidewall/s of said recess/es. In this manner even the insertion/extraction of the cellular energy-absorbing insert, during assembly or disassembly, is facilitated.

[0010] The protective layer can be absent in correspondence of said vent/s, for avoiding to close or restrict it/them.

[0011] Preferably, the protective layer can be a coating or a film layered over the recess of the foam liner. In this manner, the coating can be sprayed overthe inner surface/s of the recess. Alternatively, the film can be easily attached, for example with an adhesive, to the bottom of the recess.

[0012] In particular, the helmet can comprise an outer shell for improving the wearer's head protection and for reducing the risk of damages to the foam of the foam liner.

[0013] Advantageously, the cellular energy-absorbing insert can comprise a plurality of interconnected open cells configured to absorb energy by plastic deformation in response to a longitudinal compressive load applied to said cells. This kind of cellular material provides excellent results in terms of energy-absorption and is very light weight. [0014] In particular, each cell can comprise a tube having a sidewall/s and a longitudinal axis, and the cells are connected to each other through their sidewalls. This feature enables the production of a sheet of interconnected side-by-side cells which facilitate the helmet manufacturing.

[0015] Each cut-out can be a hole in the cellular energy-absorbing insert that is significantly bigger than one open cell. This means that several cells are removed from the cellular energy-absorbing insert when a cut-out is provided.

[0016] Advantageously, the cellular energy-absorbing insert can have synclastic properties. This feature makes the cellular energy-absorbing insert spherically deformable without distortion of cells. In this way, the cellular energy-absorbing insert can be realized as a flat sheet that is subsequently manually curved and inserted in the recess.

[0017] Preferably, the cellular energy-absorbing insert can be configured to provide an improved shock absorbing protection as compared with the foam liner. The cellular energy-absorbing insert has higher performance in term of energy absorption than the foam liner. Moreover, being independent from the foam liner, the cellular energy-absorbing insert can be arranged in specific areas of the helmet for improving the protection of certain parts of the wearer's head.

[0018] In particular, the foam liner can be made of a polymeric expanded foam. This material makes the foam liner easy to be manufactured and moulded.

[0019] A further scope of the present invention is represented by a manufacturing process of a helmet comprising the steps of: providing at least a cellular energy-absorbing insert; cutting-out one or more portions of the cellular energy-absorbing insert; deforming the cellular energy-absorbing insert to a curved shape; and arranging the curved cellular energy-absorbing insert in a foam liner having at least one recess shaped to accommodate the at least one cellular energy-absorbing insert. This method allows to easily realize a helmet having cut-outs in the inner cellular insert.

[0020] These and other advantages will be better understood thanks to the following description of different embodiments of said invention given as non-limitative examples thereof, making reference to the annexed drawings.

DRAWINGS DESCRIPTION

[0021] In the drawings:

Fig. 1 shows a schematic cross-sectional view of a helmet according to the present invention;

Fig. 2 shows a schematic cross-sectional view of another helmet according to the present invention; Fig. 3 shows a first type of cellular energy-absorbing insert before being curved, in the upper portion of Fig. 3, and after its deformation phase, in lower portion of Fig. 3 in which the cellular energyabsorbing insert is longitudinally sectioned;

Fig. 4 shows a second type of cellular energy-absorbing insert before being curved, in the upper portion of Fig. 3, and after its deformation phase, in lower portion of Fig. 3 in which the cellular energy-absorbing insert is longitudinally sectioned;

Fig. 5 shows a partial schematic cross-sectional view of the interaction between foam liner and cellular energy-absorbing insert during an impact.

DETAILED DESCRIPTION

[0022] The following description of one or more embodiments of the invention refers to the annexed drawings. The same reference numbers indicate equal or similar parts. The object of the protection is defined by the annexed claims. Technical details, structures or characteristics of the solutions here-below described can be combined with each other in any suitable way.

[0023] In the following the term "cellular energy-absorbing insert" can be abbreviated with the term "cellular insert".

[0024] With the reference number 1 is represented a helmet according to the present invention.

[0025] The helmet 1 comprises an outer foam liner 3, preferably made of a polymeric expanded foam like EPS or EPP. The helmet 1 also comprises one or more cellular inserts 2 arranged in respective recesses 4 of the foam liner 2. In the first embodiment, depicted in Fig. 1, the helmet 1 comprises more cellular inserts 2, while in the second embodiment, depicted in Fig. 2, the helmet 1 comprises one cellular insert 2.

[0026] Terms "outer" and "inner" refer to an ideal direction that goes from the cavity 13 of the helmet 1 wherein the head of the wearer can be positioned to the outside of the helmet 1.

[0027] Each recess 4 is shaped so as to hold a respective cellular insert 2. To make it possible, the outer face of the cellular insert 2 is larger than the inner face of the cellular insert 2 and the mouth of the recess 4 is stricter than the bottom of the recess 4. Moreover, the shape of the recess 4 is substantially complementary to the shape of the corresponding cellular insert 2, as shown in Figs. 1,2.

[0028] The foam liner 3 comprises vents 6, thus passages that extend through the foam liner's thickness, for allowing air to enter into the helmet 1, as shown in Figs. 1,2. [0029] The cellular insert 2 comprises one or more cut-outs 5, thus apertures that extend through the cellular insert's thickness, as shown in Figs. 1,2.

[0030] The cellular insert 2 comprises a cellular energy-absorbing material that performs better, in term of shock absorption, than traditional foam materials, in particular in terms of absorption of compressive impact energy.

[0031] The cellular insert 2 is made of a plurality of interconnected open cells 7. These cells 7 are configured to absorb energy by plastic deformation in response to a longitudinal compressive load, thus an out-of-plane compression.

[0032] Each cell 7 creates a tube having a sidewall and a longitudinal axis. Through each cell 7 an airflow can transit in a direction concurrent with the longitudinal axis.

[0033] The cells 7 are interconnected via their sidewalls 8. A bonding agent can keep the cells 7 joined together. The cells 7 can be welded to each other via a partial melting of their sidewalls 8. Alternatively, the cells 7 can be bonded by means of adhesive layers (not shown) interposed between adjacent sidewalls 8.

[0034] The cellular insert 2 can be realized from a flat sheet 14 of interconnected cells 7 that subsequently is curved. The flat sheet 14 of cells 7, as shown in Figs. 3,4, is like a tile/brick of interconnected cells 7 having parallel longitudinal axes. For obtaining the shape of the cellular insert 2, the flat sheet 14 is firstly cut according to a specific shape and secondly is curved. The flat sheet 14 has normally a constant thickness.

[0035] The flat sheet 14 of cells 7 can be curved via thermoforming or manually if it has synclastic properties. The flat sheet of cells 7 of Figs. 3,4 can thus assume a single-curved shape or a doublecurved shape.

[0036] The cells 7 can be cylindrical tubes, as in Figs. 1,4. The tubes depicted in Figs. 1,4 have a circular cross-section. Alternatively, cells 7 can comprise sidewalls 8 bonded together to form tubes having other shapes. In particular, the cross-section of the cells/tubes 7 can be a square, a hexagon, a non-uniform hexagon, a re-entrant hexagon, a chiral truss, a diamond, a triangle.

[0037] In the example of Fig. 3, the cells 7 have an arrowhead shape. This kind of shape of cells 7 exhibits synclastic properties. Therefore, the sheet 14 of cells 7 can be spherically curved with hands, as shown in Fig. 3. Vice versa, the cylindrical cells 7 do not exhibit synclastic properties, therefore the curved shape of the cellular insert 2 is achieved by thermoforming the flat sheet 14, as shown in Fig. 4. [0038] The thickness of the sheet 14 from which the cellular insert 2 is obtained can be between 15 and 40 mm.

[0039] When the cells 7 have a circular cross-section, the outer diameter of the circular crosssection can range between 2,5 and 8 mm, and the wall thickness of said cells 7 can range between 0,05 and 0,3 mm. According to these dimensional values, the energy absorption and the weight of cellular insert 2 is optimized.

[0040] The cut-out 5 in the cellular insert 2 is a hole that is much bigger than a single cell 7. Substantially, from the flat sheet 14 of open cells 7, as previously described, one or more big apertures are realized by cutting-out portion/s of the cellular insert 2. The result, shown in Figs. 3,4, is a cellular insert 2 having at least one hole, namely the cut-out 5, that is significantly bigger than one single open cell 7. Indeed, each cut-out 5 can remove several cells 7 from the sheet 14 of cells 7. The airflow that can transit through the cut-out 5 is thus significantly higher than the airflow that can transit through one open cell 7.

[0041] In order to achieve a curved cellular insert 2 with one or more cut-outs 5, it's preferable to perform the cut-outs 5 in the flat sheet 14, as shown in Figs. 3,4. Indeed, it's easier to cut a portion from a flat sheet 14 of cells 7, than to cut it from a curved one.

[0042] Therefore, the manufacturing process for achieving a helmet according to the present invention comprises the following steps. Firstly, one or more cellular inserts 2, preferably in the form of flat sheets 14 of interconnected cells 7, are provided. In a second phase, from each flat sheet 14 are cut away one or more portions, in order to achieve said cut-out/s 5. After that, the flat sheet 14 is deformed for achieving a curved shape. Subsequently, the curved cellular insert 2 is inserted in the corresponding recess 4 of the foam liner 3.

[0043] The position of a cut-out 5 of the cellular insert 2 is preferably chosen so that each cut-out 5 is aligned and centred with respect to a corresponding vent 6, as shown in Figs. 1,2.

[0044] The outer surface of the helmet 1 can be covered with an outer shell 12 as shown in Figs. 1,2. Alternatively, the outer surface of the helmet 1 is devoid of an outer shell 12. The outer shell 12 can be rigid or soft depending on the final destination of the helmet 1.

[0045] The helmet 1 can also comprise a protective layer 10 arranged on the inner surface of the foam liner 3. In particular, the protective layer 10 is arranged on the surface of the recess 4.

[0046] The protective layer 10 can be a film attached, or otherwise layered, to the bottom of the recesses 4, as schematically depicted in Fig. 1. Alternatively, the protective layer 10 can be a coating sprayed, or otherwise distributed, over the inner surface of the recess 4, as schematically depicted in Fig. 2. In the latter case, the protective layer 10 covers both the bottom and the sidewalls 11 of the recess 4.

[0047] The protective layer 10 can be made of a low-friction material, like PTFE, polycarbonate or polyamide, for facilitating a relative translation between the cellular insert 2 and the foam liner 3.

[0048] The protective layer 10 is preferably absent in correspondence of the vents 6, for not inhibiting an air transit through the vents 6, as shown in Figs. 1,2.

[0049] In an alternative embodiment (not shown), the protective layer 10 crosses the vent/s 6, but in this case, the protective layer 10 is permeable to air for allowing a ventilation of the wearer's head.

[0050] Fig. 5 shows a detailed view of a portion of the helmet 1 when an oblique impact occurs. The term "oblique impact" means an impact comprising both a normal component and a tangential component. Terms "normal" and "tangential" make reference to the outer surface of the helmet 1. [0051] When the helmet 1 impacts an object, the helmet 1 is subject to a load, schematically depicted with an arrow and the reference sign "F" in Fig. 5. The load F tends to rotate the helmet 1 and with it the head of the wearer, that is attached to the helmet 1 through a retaining system (not shown). Despite this, the cellular insert 2 slides over the protective layer 10 attached to the foam liner 3. Therefore, a part of the helmet 1 rotates underthe load F, while the cellular insert 2 in-plane compresses absorbing the tangential component of the load F and transferring less impact energy to the wearer's head. The cut-out 5 of the cellular insert 2 is sized so that during an in-plane compression, the edges 9 of the cells 7 do not reach the vent 6, as shown in Fig. 5.

[0052] In the known helmets, the edges of the sidewalls of the cells tend to enter in the aperture of the vent and to slow down or stop the translation of the cellular insert 2, creating serious problems to the wearer's head. In the present invention, the size of the cut-out 5 is increased with respect to the size of the inner aperture of vent 6. This allows to avoid that top edges 9 of the cells 7 reach the aperture of the vent 6 during an in-plane compression. The risk of a jamming of some cells 7 in the vent 6 is prevented or limited.

[0053] If an outer shell 12 is present, the vent 6 also crosses the outer shell 12.

[0054] The vents 6 can lie in correspondence of the recesses/es 4 or not. The helmet 1 can also comprise vents lying outside the perimeter of the recess/es 4 (not shown). In this case, these vents run from the outer to the inner surfaces of the helmet 1.

[0055] Concluding, the invention so conceived is susceptible to many modifications and variations all of which fall within the scope of the inventive concept, furthermore all features can be substituted to technically equivalent alternatives. Practically, the quantities can be varied depending on the specific technical requirements. Finally, all features of previously described embodiments can be combined in any way, so as to obtain other embodiments that are not herein described for reasons of practicality and clarity.

[0056] Legend of reference signs:

1 helmet

2 cellular energy-absorbing insert

3 foam liner

4 recess

5 cut-out (of cellular energy-absorbing insert)

6 vent

7 cell

8 sidewall (of cell)

9 edge (of cell)

10 protective layer

11 sidewall (of recess)

12 outer shell

13 cavity (for wearer's head)

14 flat sheet (of cells)

Claims

SET OF CLAIMS

1. Helmet (1) comprising:

- at least a cellular energy-absorbing insert (2);

- a foam liner (3) comprising at least one recess (4) shaped to accommodate the at least one cellular energy-absorbing insert (2); the foam liner (3) also comprises one or more air vents (6) for allowing an air transit from outside the helmet (1) to the cellular energy-absorbing insert (2); wherein the cellular energy-absorbing insert (2) comprises one or more cut-outs (5) provided in correspondence of said one or more vents (6).

2. Helmet (1) according to claim 1, wherein each cut-out (5) is centred on the corresponding vent (6).

3. Helmet (1) according to claim 1 or 2, comprising a protective layer (10) attached to the foam liner (3) in correspondence of bottom/s of said recess/es (4).

4. Helmet (1) according to claim 3, wherein the protective layer (10) is also attached to sidewall/s (11) of said recess/es (4).

5. Helmet (1) according to claim 3 or 4, wherein the protective layer (10) is absent in correspondence of said vent/s (6).

6. Helmet (1) according to claim 3, 4 or 5, wherein protective layer (10) is a coating or a film layered on the recess (4) of the foam liner (3).

7. Helmet (1) according to any one of preceding claims, comprising an outer shell (12).

8. Helmet (1) according to any one of preceding claims, wherein the cellular energy-absorbing insert (2) comprises a plurality of interconnected open cells (7) configured to absorb energy by plastic deformation in response to a longitudinal compressive load applied to said cells (7).

9. Helmet (1) according to claim 8, wherein each cell (7) comprises a tube having sidewall/s (8) and a longitudinal axis, and the cells (7) are connected to each other through their sidewalls (8).

10. Helmet (1) according to claim 8 or 9, wherein each cut-out (5) is a hole in the cellular energyabsorbing insert (2) that is significantly bigger than one open cell (7).

11. Helmet (1) according to any one of preceding claims, wherein cellular energy-absorbing insert (2) has synclastic properties.

12. Helmet (1) according to any one of preceding claims, wherein the cellular energy-absorbing insert (2) is configured to provide an improved shock absorbing protection as compared with the foam liner (3).

13. Helmet (1) according to any one of preceding claims, wherein the foam liner (3) is made of a polymeric expanded foam.

14. Manufacturing process of a helmet (1) comprising the steps of:

- providing at least a cellular energy-absorbing insert (2);

- cutting-out one or more portions of the cellular energy-absorbing insert (2);

- deforming the cellular energy-absorbing insert (2) to a curved shape;

- arranging the curved cellular energy-absorbing insert (2) in a foam liner (3) having at least one recess (4) shaped to accommodate the at least one cellular energy-absorbing insert (2).