Protection device with a reactive structure

Abstract

A protection device (1) comprising: - a plurality of segments (2) and - a reactive structure (3), wherein the reactive structure (3) comprises a plurality of reactive layers (4) joined along at least one intersection (5), each reactive layer (4) separating two segments (2) of said plurality of segments (2).

Description

[0001] Protection device with a reactive structure

[0002] Description:

[0003] The present invention relates to a protection device, particularly a helmet, with a reactive structure as well as a method of fabrication of such a protection device.

[0004] While protection devices are used in many different fields, such as for example in the automotive sector, for barriers, armor or for helmets, they all serve to protect structures or objects from impacts onto the protection device. Particularly, in case of helmets, said object may be a human head, such that the protection device serves to protect a user wearing the protection device from head and neck injuries arising from impacts onto the protection device. Since impacts onto protection devices usually result from uncontrolled events, such as accidents, collisions or falls, the direction and absolute value of the force acting on protection device may vary substantially, depending on the impact scenario. For example, in case of helmets, particularly bicycle helmets, oblique impacts at large relative velocities between the protection device and the object can cause strong rotational forces transmitted to the head and neck of the user wearing the protection device, representing severe risks of injuries to the user. For the above reasons, protection device developments aim at controlling the transmission of forces between objects and the structure or object to be protected through the protection device to minimize a damage of the structure or object to be protected for various impact scenarios.

[0005] Based on the above, it is subject of the present invention to provide a protection device that is capable of offering protection for structures or objects for various impact scenarios. Particularly, in case of helmets, particularly bicycle helmets, the invention aims at providing a protection device for helmets that reduces the risk for the above-mentioned injuries related to oblique impacts causing a tangential force acting on the protection device.

[0006] This problem is solved by a protection device with the features of claim 1 and a fabrication method according to claim 16. Advantageous embodiments of the invention are given in the corresponding subclaims and described in the following.

[0007] A first aspect of the invention relates to a protection device comprising a plurality of segments and a reactive structure. The reactive structure comprises a plurality of reactive layers joined along at least one intersection, wherein each reactive layer separates two segments of said plurality of segments. The reactive structure may also be referred to as an impact mitigating structure.

[0008] Particularly, at least some, more particularly all reactive layers separate two neighboring segments, respectively. According to an embodiment, one of the two segments is an inner segment arranged at or forming an inside of the protection device arrangeable on or near a structure or an object to be protected by the protection device and wherein the other segment of the two segments is an outer segment.

[0009] For example, if the protection device is used as a helmet or in helmets, particularly cycling helmets, the object to be protected may be a head, such that the first segment is preferably arrangeable on a head of a user wearing the helmet. To this end, the first segment may comprise an essentially hemispherical shape adapted to the shape of a human scalp. The first segment may be further equipped with a cushioning structure arrangeable between the head of a user and the first segment to increase the wearing comfort. Just like the first segment, also the second or more segments, particularly all segments of the protection device may comprise curved outer surfaces, such that the protection device comprising these kinds of segments at least in sections assumes a helmet-shape.

[0010] However, this is just an example and the protection device according to the invention is not limited to helmets but may likewise find application as a protection device in the automotive sector; for armor, particularly body armor or tank armor or other applications in which structures or objects are to be protected in impacts.

[0011] Particularly, the reactive layers separate different segments, i.e. different reactive layers do not separate the same two neighboring segments. The reactive layers are thus preferably not to be understood as different sections of a structure such as a layer separating the same two neighboring segments.

[0012] In a preferred embodiment, the segments comprise or consist of an energy absorbing material such as expanded polystyrene (EPS) or polyurethane, particularly expanded polyurethane (EPU), or polypropylene, particularly expanded polypropylene (EPP). As such, the segments may be configured to absorb a fraction, particularly a majority of an impact force acting on the segments so as to reduce the amount of energy transmitted through the protection device.

[0013] According to an embodiment, the at least one intersection interconnects adjacent reactive layers, wherein the adjacent reactive layers extend along different directions away from the intersection. As such, the individual reactive layers forming the reactive structure are structures which are oriented at different angles to each other.

[0014] Particularly, the reactive structure comprises a plurality of intersections. Hence, the reactive structure may be formed as a web of reactive layers interconnected by a plurality of intersections. The segments may thus form blocks that are separated from each other at least in a first portion of the protection device by the reactive layers. However, the segments may be connected with each other in at least a second portion of the protection device. In an alternative embodiment, at least some, particularly all segments are fully separated from each other by the reactive layers such that the segments are not connected with each other in the protection device.

[0015] For example, adjacent reactive layers extending along different directions away from one intersection comprise an angle of between 20° and 160°, particularly between 50° and 130°, more particularly between 80° and 100° between each other.

[0016] Particularly, the intersection is an intersection point or an intersection line. The reactive structure may comprise solely intersection points or intersection lines or the reactive structure may comprise both at least an intersection point and an intersection line. For example, in case of an intersection point, the intersection point may coincide with an origin of a cartesian coordinate system, wherein the reactive layers form planes arranged along the axes of the coordinate system. Despite being denoted an intersection point or line, the intersection point or intersection line may still represent a three-dimensional structure to provide sufficient stability to the reactive structure, whose reactive layers are joined by the intersection. However, the intersection line is characterized in that its spatial extent into a first spatial direction is larger than its spatial extent into the other two spatial directions oriented perpendicular to the first spatial direction.

[0017] In another embodiment, the respective reactive layer comprises displacement promoting means or elements configured to promote a displacement between the two segments, such that if at least one segment of said two segments is subject to an impact force, the at least one segment is configured to displace relative to the other segment. By allowing for a displacement of segments, hazardous accelerations of a head of a user wearing the protection device that may occur upon an impact force are advantageously reduced. Moreover, in case of energy absorbing segments, the protection device according to this embodiment advantageously provides both an absorption of energy of the impact and a displacement by the segment(s).

[0018] Particularly, the displacement between segments may depend on a tangential force component of the impact force, wherein the tangential force component is directed along an outside of a segment subjected to the impact force.

[0019] According to another embodiment, the displacement promoting elements comprise rollable elements such as rolls, balls, beads or spheres. The rollable elements may comprise a circular cross-section or cross-sections deviating from a perfectly circular shape, for example an approximately elliptical cross-section. The shape of the cross-section affects the rolling resistance of the rollable elements, wherein the rolling resistance increases for stronger deviations from a perfectly circular cross-section. Preferably, according to an embodiment, the rollable elements are formed from a material comprising a Young’s modulus in the range from 0.5 GPa to 10 GPa.

[0020] Particularly, according to a preferred embodiment, the rollable elements comprise a diameter in the range from 0.5 to 5 mm, wherein particularly the diameter is 2 mm.

[0021] In an alternative embodiment, the displacement promoting means comprises a gel or a lubricant configured to promote a displacement between different segments by means of a sliding motion.

[0022] In yet another embodiment, the respective reactive layer comprises an interface arranged between the rollable elements and each of the two segments, wherein the interfaces and the rollable elements comprise a higher stiffness than the two segments. An ‘interface’ according to this embodiment is preferably to be understood as a flat physical layer.

[0023] Preferably, the rollable elements, particularly the rollable elements rolling on one or more interfaces are configured to roll with a low rolling resistance in the range from 0.0001 to 0.2, preferably in the range from 0.02 to 0.05, preferably in the range between 0.025 to 0.04 between the rollable elements and the energy absorbing layer or between the rollable elements and the interface(s). A particularly preferred rolling resistance amounts to about 0.025. Another particularly preferred rolling resistance amounts to about 0.04.

[0024] According to another embodiment, upon said impact force acting on the at least one segment, the at least one segment is configured to displace along the reactive layer, such that the direction of extension of the reactive layer provides or defines a direction of displacement of the at least one segment subject to the impact force. In other words, the reactive layers act as guides for the segments, such that the geometry of the reactive layers defines the translational and / or rotational degrees of freedom of the segments between the reactive layers. As such, the displacement of the segments may be controlled by the geometry of the reactive structure, particularly of the reactive layers.

[0025] In another embodiment, the protection device comprises at least one connecting element connecting the two segments separated by the respective reactive layer, wherein the at least one connecting element is configured to fracture and / or shear upon a predetermined force acting on the at least one connecting element, such that the fracturing and / or shearing of the at least one connecting element allows for displacement between the two segments separated by the respective reactive layer.

[0026] Preferably, the at least one connecting element is provided in combination with the displacement promoting means or elements, such that a fracturing and / or shearing of the at least one connecting element enables the displacement between the two segments promoted by the displacement promoting means or elements. The at least one connecting element may retain the displacement promoting means or elements in a fixed position within the protection device in absence of a force acting on the protection device, wherein the fracturing and / or shearing of the at least one connecting element upon an impact force causes a loss of the retaining function, allowing for a displacement of the at least one segment relative to the other segment.

[0027] Particularly, different connecting elements each with a different predetermined force causing a fracturing of the respective connecting element are used in one protection device. For example, if used for helmets, particularly cycling helmets, connecting elements fracturing at lower forces may be used to retain segments configured to displace along a longitudinal axis of the protection device oriented in the direction of view of a user wearing the protection device compared to connecting elements fracturing at higher forces that may be used to retain segments configured to displace along a transverse axis of the protection device. In this example, a displacement of segments along the longitudinal direction, which typically takes the largest component of the impact force particularly in cycling accidents, is favored. As such, the arrangement of connecting elements with different fracturing forces on the protection device provides a favored direction of displacement that can thus be tailored to different impact scenarios.

[0028] In another embodiment, the at least one connecting element is integrally formed with the two segments that are separated by the reactive layer. As such, the at least one connecting element may comprise or consist of the same material like the two segments. The at least one element may thus form a homogeneous connection between the two segments.

[0029] Particularly, the at least one connecting element is arranged in or formed by a portion of the protection device joining the two segments that are separated by a reactive layer of the protection device. More particularly, the two segments may be separated by the respective reactive layer in a first portion of the protection device, wherein the at least one connecting element is arranged in or formed by a second portion of the protection device joining the two segments.

[0030] Particularly, according to an embodiment, the protection device, particularly the at least one connecting element is configured such that the tangential force component required to activate a displacement between the segments, for example by means of a rolling of balls of the reactive layer, is about 0.1 kN, or such that an energy introduced by the impact force has to exceed a threshold of 2.5 Joule to result in a displacement between the segments, for example by means of the rolling of the balls. In an embodiment, upon said impact force on said at least one segment, the at least one segment is configured to at least partially, particularly completely separate from the protection device.

[0031] According to an embodiment, the reactive structure is at least partially, particularly completely encapsulated by the segments.

[0032] According to an embodiment, the reactive structure is a connected structure. A connected structure in the context of the present invention is to be understood as a topological space that cannot be represented as the union of two or more disjoint non-empty open subsets. Even as a connected structure, the reactive structure, particularly the reactive layers forming the reactive structure, may have complex shapes such as for example a plurality of reactive layers extending into different directions away from an intersection or a web of interconnected reactive layers extending into different directions away from a plurality of intersections.

[0033] In another embodiment, the protection device further comprises an outer layer arranged on at least one segment, wherein the outer layer forms an outside of the protection device. For example, the outer layer may be a protective layer or a heat resistant ink layer. The outer layer can be a polymer layer, particularly a polyvinylchloride layer. The outer layer may comprise a thickness of below 0.1 mm.

[0034] According to another embodiment, the reactive structure forms at least one opening, wherein a segment is arranged particularly flush with the opening or wherein the segment is extending through the opening.

[0035] A second aspect of the invention is related to a method of fabrication for a protection device according to the first aspect of the invention. The method comprises the following steps: i) providing the reactive structure and ii) cladding the reactive structure with at least one material, particularly an energy absorbing material, to provide the segments adjacent to the reactive structure.

[0036] For example, the reactive structure may be fabricated or formed by means of casting, particularly die casting, injection molding, 3D-printing or thermoforming, particularly twin-sheet thermoforming. Twin-sheet thermoforming is particularly advantageous as it allows to form two interfaces that may be used to delimit the reactive structure and at the same time to confine the displacement promoting means or elements between the interfaces.

[0037] Particularly, the reactive structure may be overmolded with a material, particularly an energy absorbing material, whereby the segments are formed around the reactive structure. Moreover, the reactive structure may be embedded in a mold, such that the segments are formed around the reactive structure.

[0038] Exemplary embodiments are described below in conjunction with the Figures. The Figures are appended to the claims and are accompanied by text explaining individual features of the shown embodiments and aspects of the present invention. Each individual feature shown in the Figures and / or mentioned in the text of the Figures may be incorporated (also in an isolated fashion) into a claim relating to the protection device according to the present invention.

[0039] Fig. 1 shows a first portion of a protection device according to an embodiment of the invention in a perspective view;

[0040] Fig. 2 shows a cut view through a protection device according to an embodiment of the invention, wherein a first and a second segment are separated from each other in a first portion of the protection device via a reactive structure comprising rollable elements and

[0041] Fig. 3 shows the embodiment of Fig. 2, where the second of the two neighboring segments is displaced relative to the first segment upon an impact force acting on the second segment.

[0042] Fig. 1 shows a first portion 13 of a protection device 1 according to an embodiment of the invention. In this first portion 13 of the protection device 1 , three segments 2,21 ,22,23 are separated from each other by a reactive structure 3. The reactive structure 3 shown in this first portion 13 forms three reactive layers 4,41 ,42,43 extending along different directions away from an intersection 5 interconnecting the reactive layers 4. A first segment 21 is separated from a second segment 22 via a first reactive layer 41. The second segment 22 is separated from a third segment 23 via a second reactive layer 42. The third segment 23 is separated from the first segment 21 by a third reactive layer 43. The intersection 5 in this embodiment forms an intersection line extending through first portion 13 of the protection device 1 shown in Fig. 1. As such, every reactive layer 4 separates two neighboring segments 2.

[0043] The reactive structure 3 comprises displacement promoting elements 6, particularly rollable elements 7 such as beads, rolls or spheres, which are configured to promote a displacement between the segments 2, such that if at least one segment 2 is subject to an impact force acting on the segment 2, the at least one segment 2 is configured to displace relative to the other segments 2. By allowing for a displacement of the segments 2, hazardous accelerations of a head of a user wearing the protection device 1 that may occur upon an impact force are advantageously reduced. The reactive layers 4 of the reactive structure 3 define favored displacement directions of the segments 2. For example, the reactive layers 4 shown in Fig. 1 are arranged such that if an impact force acting on one of the segments 2 comprises a force component oriented parallel to the intersection 5 interconnecting the reactive layers 4, the segment 2 subject to the impact force is configured to displace relative to the other segments 2 along the intersection line and the reactive layers 4 adjacent to the displacing segment 2. Particularly, the reactive layers 4 may be arranged along a longitudinal axis of the protection device 1 oriented in the direction of view of a user wearing the protection device 1 such that the segments 2 are configured to displace along the longitudinal axis upon an impact force acting at least partially along said longitudinal axis, which is the case for example in typical cycling accidents. However, the reactive layers may also be arranged along other axes such that the displacement and particularly a mechanical resistance against the displacement may be tailored.

[0044] Fig. 2 shows a cut view through a protection device 1 according to an embodiment of the invention, wherein two neighboring segments 2, particularly a first and a second segment 21 ,22, are separated from each other in a first portion 13 of the protection device 1 by a reactive layer 4 of a reactive structure 3 comprising rollable elements 7. The reactive structure 3 further comprises interfaces 8 arranged between the rollable elements 7 and the segments 2. Preferably, the interfaces 8 and the rollable elements 7 comprise a higher stiffness than the segments 2, such that upon an impact force, the rollable elements 7 may roll on at least one interface 8 with an advantageously low rolling resistance, allowing for an efficient displacement of the at least one segment 2 subject to the impact force.

[0045] The protection device 1 shown in Fig. 2 further comprises an outer layer 9 or a coating forming an outside 11 of the protection device 1. The outside 11 is oriented away from an inside 12 of the protection device 1 , wherein the inside 12 is configured to be arranged on a head of a user wearing the protection device 1.

[0046] As can further be seen in Fig. 2, the reactive structure 3 is encapsulated by the segments 2, wherein the reactive layer 4 of the reactive structure 3 separates the segments 2 from each other in a first portion 13 of the protection device 1. As such, the protection device 1 is advantageously easy and cost-efficient to fabricate, as the reactive structure 3 may be simply overmolded with the energy absorbing material forming the segments 2. Particularly, the reactive structure 3 may be a connected structure comprising a web of interconnected reactive layers 4. Such a protection device 1 can be fabricated for example by placing the reactive structure 3 in a mold comprising the energy absorbing material for forming the segments 2.

[0047] While the two segments 2, i.e. the first and the second segment 21 ,22 shown in Fig. 2, are separated from each other by the reactive layer 4 in the first portion 13 of the protection device 1 , the two segments 2 are joined in two second portions 14 of the protection device 1. In the typical case of an impact force acting onto the outer layer 9 and hence on the second segment 22 comprising a tangential force component FTdirected tangentially to the outside 11 or the outer layer 9 of the protection device 1 , the joints of the two segments 2 take up a fraction of the force which may cause the two segments 2 to separate upon the impact force, such that they may move relative to each other via the rollable elements 7. As such, the second portions 14 of the protection device 1 form connecting elements 10 that are configured to fracture upon a predetermined force acting on the connecting elements 10, whereby the fracturing of the connecting elements 10 allows or a displacement of the segments 2 relative to each other.

[0048] In particular, the fracturing of the connecting elements 10 can cause a separation of a segment 2 from the protection device 1 upon the impact force with a tangential force component FTtangentially to the outer layer 9, as schematically illustrated in Fig. 3. It is noted that the cut views shown in Fig. 2 and Fig. 3 schematically depict a single reactive layer 4 between two neighboring segments 2, while a protection device 1 according to the invention comprises a plurality of interconnected reactive layers 4, particularly wherein each reactive layer 4 separates two neighboring segments 2.

[0049] List of reference signs

[0050] Protection device 1

[0051] Segment 2

[0052] Reactive structure 3

[0053] Reactive layer 4

[0054] Intersection 5

[0055] Displacement promoting means or elements 6

[0056] Rollable element 7

[0057] Interface 8

[0058] Outer layer 9

[0059] Connecting element 10

[0060] Outside 11

[0061] Inside 12

[0062] First portion 13

[0063] Second portion 14

[0064] First segment 21

[0065] Second segment 22

[0066] Third segment 23

[0067] First reactive layer 41

[0068] Second reactive layer 42

[0069] Third reactive layer 43

[0070] Tangential force component FT

Claims

Patent claims:

1. A protection device (1) comprising: a plurality of segments (2) and a reactive structure (3), wherein the reactive structure (3) comprises a plurality of reactive layers (4) joined along at least one intersection (5), each reactive layer (4) separating two segments (2) of said plurality of segments (2).

2. The protection device (1) according to claim 1 , wherein the at least one intersection (5) interconnects adjacent reactive layers (4), wherein the adjacent reactive layers (4) extend along different directions away from the intersection (5).

3. The protection device (1) according to one of the claims 1 or 2, wherein the respective reactive layer (4) comprises displacement promoting elements (6) configured to promote a displacement between the two segments (2), such that if at least one segment (2) is subject to an impact force, the at least one segment (2) is configured to displace relative to the other segment (2).

4. The protection device (1) according to claim 3, wherein the displacement promoting elements (6) comprise rollable elements (7).

5. The protection device (1) according to claim 4, wherein the respective reactive layer (4) further comprises an interface (8) arranged between the rollable elements (7) and each of the two segments (2), wherein the interfaces (8) and the rollable elements (7) comprise a higher stiffness than the two segments (2).

6. The protection device (1) according to claim 2 and one of the claims 3 to 5, wherein upon said impact force on the at least one segment (2), the at least one segment (2) is configured to displace along the reactive layer (4), such that the direction of extension of the reactive layer (4) provides a direction of displacement of the at least one segment (2) subject to the impact force.

7. The protection device (1) according to one of the claims 2 to 6, wherein the at least one intersection (5) is an intersection point or an intersection line.

8. The protection device (1) according to one of the preceding claims, wherein the protection device (1) comprises at least one connecting element (10) connecting the two segments (2) separated by the respective reactive layer (4), wherein the at7 least one connecting element (10) is configured to fracture and / or shear upon a predetermined force acting on the at least one connecting element (10) , such that the fracturing and / or shearing of the at least one connecting element (10) allows for displacement between the two segments (2) separated by the respective reactive layer (4).

9. The protection device according to claim 8, wherein the at least one connecting element (10) is integrally formed with the two segments (2) that are separated by the reactive layer (4).

10. The protection device (1) according to one of the claims 3 to 9, wherein upon said impact force on said at least one segment (2), the at least one segment (2) is configured to at least partially, particularly to completely separate from the protection device (1).

11. The protection device (1) according to one of the preceding claims, wherein the reactive structure (3) is at least partially, particularly completely encapsulated by the segments (2).

12. The protection device (1) according to one of the preceding claims, wherein the reactive structure (3) is a connected structure.

13. The protection device (1) according to one of the preceding claims, further comprising an outer layer (9) arranged on at least one segment (2), wherein the outer layer (9) forms an outside (11) of the protection device (1).

14. The protection device (1) according to one of the preceding claims, wherein one of the two segments (21) is an inner segment arranged at or forming an inside (12) of the protection device (1) arrangeable on or near a structure or an object to be protected by the protection device (1) and wherein the other segment (21) of the two segments (2) is an outer segment.

15. The protection device (1) according to one of the preceding claims, wherein the segments (2) comprise or consist of an energy absorbing material such as expanded polystyrene (EPS), polyurethane, or polypropylene.

16. A method of fabrication for a protection device (1) according to one of the preceding claims, the method comprising the following steps: i) providing the reactive structure (3) andii) cladding the reactive structure with at least one material, particularly an energy absorbing material, to provide the segments (2) adjacent to the reactive structure (3).

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