Helmet with protective features

Specification

A first aspect of the invention relates to a helmet, particularly a helmet for cycling, according to the feature of claim 1.

A second aspect of the invention relates to a method for manufacturing a helmet, particularly a helmet according to the first aspect.

A third aspect relates to a helmet, particularly a cycling helmet having an interlocking connection between an outer protective layer and an energy-absorbing layer.

A fourth aspect relates to a helmet, particularly a cycling helmet with a plastically deformable outer protective layer according to features of claim 30.

A fifth aspect of the invention relates to a helmet, particularly a helmet for cycling, according to the feature of claim 56.

An object of the first, second and third aspect of the invention is to provide a helmet with enhanced safety features that can be manufactured particularly cost-efficient. The object is achieved by the device having the features of claim 1.

Advantageous embodiments are described in the dependent claims 2 to 21.

First aspect of the invention “Helmet with integrally formed connector elements”

According to a first aspect of the invention, a helmet comprising comprises an energy-absorbing layer, an outer protective layer, an intermediate layer arranged between the energy-absorbing layer and the protective layer, one or more connector elements extending from the energy-absorbing layer through corresponding one or more openings in the intermediate layer to the protective layer and fixedly attaching the protective layer with the energy-absorbing layer.

The energy-absorbing layer is configured to dissipate and absorb mechanical forces acting on the helmet, in order to protect the head of a person wearing the helmet. As such the energy-absorbing layer may form the inner most layer of the helmet that is arranged closest to the head. The energy-absorbing layer particularly comprises a comparably soft material, i.e. softer than the material of the intermediate layer and/or the outer protective layer.

The energy-absorbing layer may comprise expanded polystyrol (EPS) or similar compounds or foams that provide similar properties as EPS.

It is noted that on a side facing the head of a person wearing the helmet a lining layer or lining elements may be arranged for adjusting the fit of the helmet and or for reasons of comfort.

The energy-absorbing layer may comprise a plurality of layers, a plurality of layer elements, or it may be formed as a stack of layers that form the energy-absorbing layer.

Similarly, the intermediate and/or the outer protective layer may be formed from a plurality of layers, layer elements and/or a stack of layers that form the respective layer.

According to another embodiment of the invention, the intermediate layer comprises a different material than the energy-absorbing layer and/or the outer protective layer. Particularly, the intermediate layer is the stiffest and the hardest layer of the helmet.

According to another embodiment of the invention, the intermediate layer is formed and designed to provide a low-friction surface on which the outer protective layer may move in case the outer protective layer becomes disconnected from the helmet.

Particularly, the low-friction is achieved by forming the intermediate layer harder than the outer protective layer.

The intermediate layer may comprise or consist of a polycarbonate.

The intermediate layer may be connected to the energy-absorbing layer by means of a substance-to -substance bond, e.g. it may be glued to the energy-absorbing layer, such as to be permanently attached to the energy-absorbing layer. Particularly, the intermediate layer is configured to stay attached to the energy-absorbing layer even upon an impact force that ruptures the connector element such that the outer protective layer becomes disconnected from the helmet.

Regarding the impact force, the following considerations may be made. Typical impact energies for which the helmets are designed may be in the range of 50 to 200 Joules.

A casual drop of the helmet from 2m height would amount to approximately 5 to 10 Joules impact energy, which should not lead the helmet to break the connectors, to plastically deform, or to react in any other instance as claimed. Therefore, derived impact forces upon which claimed mechanisms of the helmet are released, start to take effect or are happening, should be above the corresponding impact energy of a casual drop. Therefore, impact forces at which the helmet reacts or behaves in the claimed fashion may be the forces that correspond to an impact energy in the mentioned impact energy range, i.e. in the range between 50 to 200 Joules.

Particularly, the helmets of the invention are designed and configured to behave as claimed upon impact for any energy above 80 Joules or 90 Joules.

The outer protective layer, also referred to as protective layer in the context of the current specification is arranged on a side of the helmet that faces away from the intermediate layer. As such the outer protective layer may form the outmost layer of the helmet.

According to another embodiment of the invention, the outer protective layer bonds to a circumferential rim portion of the energy-absorbing layer and - together with the energy-absorbing layer forms an enclosure of the intermediate layer.

According to another embodiment of the invention, the outer protective layer and the energy-absorbing layer form an enclosure of the intermediate layer, said enclosure comprising the intermediate layer. The bond between the outer protective layer and the energy-absorbing layer may be formed by means of welding. The outer protective layer may be formed from a plurality of layer elements that may or may not be interconnected. The layer elements may be arranged stack-wise and/ or laterally shifted to form the outer protective layer.

In case the outer protective layer disconnects from the helmet upon an impact force the outer protective layer is configured to move on the intermediate layer such as to reduce a shear stress on the head of a person.

The one or more connector elements connect the energy-absorbing layer with the outer protective layer, wherein the one or more connector elements extend through one or more corresponding opening in form of through holes in the intermediate layer. In order to increase intelligibility, in the following it may be referred to the embodiments comprising a plurality of connector elements and openings, while omitting the explicit reference to the embodiment having only one connector element and one corresponding opening. This however, is explicitly not for limiting the scope of protection to a plurality of connector elements and openings, but inclusion of a single connector element and opening is intended and comprised in the simplified formulation.

The intermediate layer therefore may be locked in between the energy-absorbing layer and the outer protective layer by means of an interlocking connection formed by the connector elements extending through the openings of the intermediate layer. In addition, the intermediate layer may be attached to the energy-absorbing layer by means of a substance-to-substance bond.

The intermediate layer may have a thickness in the range of 0.1 mm and 10 mm. Particularly, the intermediate layer is not a lacquer or varnish layer.

According to another embodiment of the invention, the connector elements are configured to rupture upon impact

According to another embodiment of the invention, the rupturing of the connector elements includes an unjoining and/or breaking of the connector elements, while the connector elements remain undeformed otherwise. This behavior stands in contrast to a behavior of the connector elements that would solely lead to a stretching or a plastic deformation of the connector elements.

Particularly, the connectors have a fracture toughness greater than 2.5 Joule, particularly greater than 10 Joules, which corresponds to a release energy force that is impacted on the helmet upon impact.

The fracture toughness may also be regarded as the energy upon which the connectors break, when exposed to said energy.

According to another embodiment of the invention, the outer protective layer is attached to the one or more connector elements by means of a substance-to- substance bond between the one or more connector elements and the protective layer.

This embodiment allows a comparably cost-efficient manufacturing of the helmet, as the outer protective layer may be attached to the connector elements by means of an adhesive. Said adhesive may be provided on a surface of the outer protective layer facing toward the intermediate layer and during manufacturing the connector elements may be attached to the outer protective layer by connecting with the adhesive and the outer protective layer.

According to another embodiment of the invention, the connector elements may be attached to the surface of the outer protective layer facing the intermediate layer by means of the substance-to-substance bond.

According to another embodiment of the invention, the protective layer is attached to the one or more connector elements by means of an interlocking connection, particularly only by means of an interlocking connection.

This embodiment allows for a cost-efficient manufacturing of the helmet, as the interlocking connection may be formed during manufacturing, either during formation of the connector elements or in a separate manufacturing step.

The interlocking connection can be established in several ways. For example, the connector elements may interlock in a recess, an opening or a protrusion of the outer protective layer. This may be achieved for example by means of a snap-in connector assembly that is formed by the connector elements and the recess, opening or protrusion of the outer protective layer.

Alternatively, the outer protective layer comprises protrusions extending toward the intermediate layer, particularly wherein said protrusions are arranged on the surface of the outer protective layer facing the intermediate layer.

Said protrusions may form though holes through which the connector elements extend such that an interlocking connection is formed between the protrusion and the connector elements.

Particularly in case the connector elements are formed by means of a expansion process, such as a hot foaming process, the interlocking connection can be formed during said process, which reduces manufacturing costs dramatically.

Alternatively, or in addition, the interlocking connection may be formed by means of through holes of the outer protective layer through which the connector elements extend.

According to another embodiment of the invention, the outer protective layer is attached to the helmet and particularly the energy-absorbing layer only by means of the interlocking connection, e.g. without an adhesive. According to another embodiment of the invention, the one or more connector elements are integrally formed with the energy-absorbing layer.

This embodiment allows for cost-efficient and efficient manufacturing as the connector elements may be formed at the same time as the energy-absorbing layer.

In particular, as the outer protective layer is formed from a different material than the energy-absorbing layer this embodiment allows manufacturing the helmet in a single production step, e.g. by arranging the intermediate layer and the outer protective layer in a mould in which the expansion of the energy-absorbing layer takes place and wherein during the expansion process, the connector elements are formed as the expanding material of the energy-absorbing layer extends through the openings of the intermediate layer and connect to the outer protective layer.

The integrally formed connector elements may form an interlocking connection with the outer protective layer as described in a previous embedment.

Alternatively, or in addition, the connector elements may be attached to the outer protective layer by means of the substance-to-substance bond that may be facilitated by an adhesive that is activated during the expansion process.

In any event, the connector elements may be designed to rupture in case a force component in a tangential direction to the outer protective layer exceeds a predefined threshold value.

The term “integrally formed” as used in the current specification may refer to connector elements that are made from the same material and in one piece as the energy-absorbing layer.

According to another embodiment of the invention, the one or more connector elements are configured to fail upon exposure to an impact force on the protective layer such that the protective layer disconnects from the helmet at least partially or area by area and in particular from the energy-absorbing layer, particularly wherein the one or more connector elements rupture upon impact.

This embodiment allows for an enhanced safety for the person wearing the helmet upon exposure of an impact force, as the outer protective layer disconnects and reduces a shear force that may act on the head of the person that would result in a forceful rotational motion of the head. The shear stress may be caused by a tangential force component acting on the outer protective layer. In case the tangential force component exceeds a predefined threshold value, the outer protective layer detaches from the helmet, as the connector elements fail.

Failure of the connector elements may be caused by rupturing of the connector elements, by rupturing of the substance. to-substance bond between the connector elements and/or by means of a rupture of the interlocking connection of the connector elements with the outer protective layer.

In case the connector elements fail the outer protective layer may slide on the intermediate layer, which reduces the shear stress attacking the head of a person wearing the helmet.

According to another embodiment of the invention, upon impact the connector elements bend or shift toward an edge of the one or more openings of the intermediate layer, such that the one or more connector elements rupture at the edge of the one or more openings.

This embodiment essentially employs the intermediate layer openings as rupturing devices that cause the connector elements to fail upon exposure to the impact force.

This allows to form the connector elements form an elastic material.

According to another embodiment of the invention, the one or more connector elements are configured to elastically deform upon exposure to an impact force on the protective layer such that the protective layer may laterally shift with respect to the energy-absorbing layer, particularly wherein upon impact the one or more connector elements remain attached to the protective layer and the energy-absorbing layer.

According to this embodiment the connector elements essentially remain connected to the outer protective layer under any circumstance but may deform such as to allow a movement of the outer protective layer on the intermediate layer in order to reduce the shear stress on the energy-absorbing layer and thus the head of the person wearing the helmet.

This embedment omits any disconnected helmet part that may harm the person wearing the helmet during an accident. According to another embodiment of the invention, the openings of the intermediate layer comprise different sizes, such that the connector elements extending through the openings differ in terms of a rupturing force at which the connector elements fail.

According to another embodiment of the invention, a density of the openings in the intermediate layer is greater than one opening per square centimeter.

According to another embodiment of the invention, the one or more connector elements are of the same material than the energy-absorbing layer.

According to this embodiment, the connector elements may be formed form the same material but be non-integrally formed from the energy-absorbing layer. In the latter case the connector elements may be attached to the energy-absorbing layer by means of an interlocking mechanism.

According to another embodiment of the invention, a cross-sectional circumference of each connector element between the intermediate layer and the protective layer is greater than a cross-sectional circumference of the connector element at the opening through which the connector element extends.

This embodiment allows for an interlocking connection of the intermediate layer with the connector elements and the energy-absorbing layer.

According to another embodiment of the invention, a circumference of the one or more openings is in the range of .5 mm to 30 mm.

According to another embodiment of the invention, the helmet comprises three or more connectors extending through three or more openings.

This allows for a fixed orientation of the outer protective layer on the energy absorbing layer and the intermediate layer.

According to another embodiment of the invention, the intermediate layer comprises or consists of a polycarbonate.

According to another embodiment of the invention, the energy-absorbing layer comprises an expanded polystyrene.

According to another embodiment of the invention, the helmet comprises a cover layer, wherein the cover layer is arranged on a side of the protective layer facing away from the intermediate layer. The cover layer may comprise a low friction surface that reduces any shear stress induced on the outer protective layer. Further, the cover layer may be designed and configured to fail upon exposure to the impact force.

Failure of the cover layer may be a breaking of the cover layer, such that the cover layer absorbs a portion of the impact energy.

The cover layer may by glued with an adhesive to the outer protective layer.

The combination of the cover layer that may break upon impact and the outer protective layer that is connected be connector elements that fail upon impact allows for two-tier protection of the person wearing the helmet.

According to another embodiment of the invention, the protective layer is harder than the energy-absorbing layer.

According to another embodiment of the invention, the protective layer is stiffer than the energy-absorbing layer.

According to another embodiment of the invention, the intermediate layer is stiffer than the energy-absorbing layer, particularly wherein the intermediate layer is at least five times stiffer than the energy-absorbing layer.

This embodiment ensures that upon impact the inner structure, i.e. the energy absorbing layer of the helmet remains intact upon impact, while the outer protective layer may move along the intermediate layer to reduces the shear stress.

According to another embodiment of the invention, the intermediate layer is a low friction layer configured to allow the protective layer to slide over the intermediate layer in case the protective layer is disconnected form the energy-absorbing layer. According to another embodiment of the invention, the helmet comprises a reactive layer arranged between the intermediate layer and the protective layer, wherein the reactive layer is configured to provide a rolling resistance in case the protective layer is disconnected from the energy-absorbing layer.

The reactive layer may comprise or consist of roll elements that are configured to perform a rolling motion or to become Tollable upon impact so as to reduce the friction between the intermediate layer and the outer protective layer by way of providing a rolling resistance.

The rolling resistance provided by the reactive layer allows for reducing the friction between the outer protective layer and the intermediate layer to a higher degree than for example a sliding resistance or sliding friction. While the rolling resistance reduces an apparent friction, it originates from a very different mechanism when compared to a any sliding mechanism that is configured to reduce a sliding friction. Particularly, the term “rolling resistance” refers to a force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface.

The rolling resistance may be quantified in terms of a coefficient of rolling resistance. Said coefficient of rolling resistance may be in the range of 0.01 to 0.05, particularly in the range of 0.02 to 0.04.

According to a second aspect of the invention, a method for manufacturing a helmet, particularly a helmet according to the invention, i.e. to the first aspect, comprises the steps of:

Forming an intermediate layer with one or more openings;

Forming a protective layer of the helmet;

From a first material forming an energy-absorbing layer of the helmet, wherein the intermediate layer is arranged such that the first material extends through the one or more openings while the energy-absorbing layer is formed and wherein the protective layer is arranged such that the intermediate layer is arranged between the energy-absorbing layer and the protective layer, wherein the first material that extends through the one or more openings forms connector elements that attach the protective layer to the energy-absorbing layer.

The method according to the invention allows manufacturing the helmet of the invention in a very cost-efficient way, as the helmet forming process as well as the assembly process is facilitated in a single step.

Particularly, the terms and definitions provided with regard to the helmet apply to the terms and definitions of the method.

According to another embodiment of the invention, a surface of the outer protective layer that faces the intermediate layer comprises an adhesive that forms a substance- to-substance bond with the one or more connector elements during formation of the energy-absorbing layer.

According to another embodiment of the invention, a surface of the protective layer that faces the intermediate layer comprises protrusions, openings and/or recesses, that are shaped such that the first material that extends through the one or more opening of the protrusions and/or recesses form an interlocking connection with the one or more connector elements.

Details on the shape of protrusions are provided in a previous embodiment and may be applied to this embedment.

According to another embodiment of the invention, the energy-absorbing layer is formed by means of an expansion process, such as a foaming or an extrusion process, wherein the protective layer and the intermediate layer are arranged in a helmet-mould that is filled with granules of comprising the first material, particularly wherein the first material is or comprises styrene and/or polystyrene, wherein the granules are then expanded by the expansion process, such that the first material, particularly expanded or extruded polystyrene, extends through the one or more openings and forms the one or more connector elements attaching the protective layer to the energy-absorbing layer.

This embedment allows for applying well-established manufacturing processes for the energy-absorbing layer to efficiently form the complete helmet in a single manufacturing step.

According to another embodiment of the invention, the expansion process is hot- foaming process, particularly wherein upon exposure of the first material to heat, also an adhesive on a surface of the protective layer facing the intermediate layer is activated such that the one or more connector elements form a substance-to- substance bond with the protective layer by means of the adhesive.

According to another embodiment of the invention, the foaming process is hot-foaming process, wherein upon exposure of the first material to heat, an adhesive on a surface of the intermediate layer facing the energy-absorbing layer is activated such that the intermediate layer is attached to the energy-absorbing layer by means of the adhesive.

According to a third aspect of the invention, a helmet comprises: an energy-absorbing layer, an outer protective layer, an intermediate layer arranged between the energy-absorbing layer and the protective layer wherein the protective layer is attached to the energy-absorbing layer by means of an interlocking connection between the outer protective layer and the energy absorbing layer.

The material properties of the energy-absorbing layer, the intermediate layer as well as the outer protective layer may be identical to the material properties of the helmet according to the first aspect.

Terms in relation to the first aspect of the helmet may also be applicable to the helmet according to the third aspect.

The interlocking connection of the outer protective layer with the energy-absorbing layer allows for enhanced rupturing properties exposure to an impact force as described in previous embodiments. Further, the helmet according to the third aspect is particularly cost-efficient and efficient to manufacture.

According to another embodiment of the invention, the interlocking connection is configured to fail upon exposure of the outer protective layer to an impact force such that the outer protective layer disconnects at least partially or area by area from the energy-absorbing layer causing a reduced shear stress on the head of the person wearing the helmet.

Upon failure of the interlocking connection the outer protective layer may move over the intermediate layer which serves as a low-friction surface.

According to another embodiment of the invention, the protective layer extends around the intermediate layer and undercuts the energy-absorbing layer at least at a rim portion of the energy-absorbing layer.

The rim portion of the helmet is particularly arranged at an outer rim of the helmet. Furthermore, the rim portions may extend at regions of the helmet that may exhibit an ventilation opening.

According to this embodiment, the outer protective layer is essence folds around the intermediate layer into the energy-absorbing layer.

According to another embodiment of the invention, the interlocking connection at the rim portion forms a volume limited by the energy-absorbing layer and the protective layer in which the intermediate layer is enclosed, particularly wherein said volume is a closed volume.

It is noted again that the outer protective layer may consist of a plurality particularly separate layer elements, each of which may be configured according to the third aspect. That is, each outer protective layer (element) may enclose the intermediate layer (element) and interlocks with the energy-absorbing layer.

This allows for a particularly good, particularly local rupture performance upon exposure of an impact force.

According to another embodiment of the invention, circumferential edges of the outer protective layer protrude into the energy-absorbing layer forming the interlocking connection.

Particularly upon impact said protruding edges may rupture or deform such as to release the outer protective layer (element) such that the outer protective layer moves over the intermediate layer (element) so as to reduce the shear stress on the head of a person wearing the helmet. According to another embodiment of the invention, one or more connector elements extending from the energy-absorbing layer through corresponding one or more openings in the intermediate layer to the protective layer and fixedly attaching the protective layer with the energy-absorbing layer.

The effect and benefits of the connector elements has been elaborated in previous embodiments and apply.

According to another embodiment of the invention, the outer protective layer extends at least at the rim portion around the intermediate layer into the energy-absorbing layer by means of interlocking elements.

These interlocking elements may deform or rupture upon exposure of the outer protective layer to an impact force such that the outer protective layer (element) may become disconnected to the remainder of the helmet.

According to another embodiment of the invention, the interlocking elements may be formed integrally with the outer protective layer or in one piece with the outer protective layer. This allows for an efficient manufacturing process.

According to another embodiment of the invention, the helmet comprises embodiments and features of any of the embodiments directed to the first aspect of the invention. +

Fourth aspect of the invention “Helmet with a plastically deformable outer protective layer”

An object of the fourth aspect of the invention is to provide a helmet with enhanced safety features that can be manufactured particularly cost-efficient. The object is achieved by the device having the features of claim 30.

Advantageous embodiments are described in the claims 31 to 55.

According to claim 30, the helmet according to the fourth aspect comprises at least an energy absorbing layer, an outer protective layer, wherein said outer protective layer is configured to plastically deform relative to the energy-absorbing layer upon exposure to an impact force having at least a tangential force component along a surface of the outer protective layer, such that a deformed portion of the outer protective layer is formed.

The energy-absorbing layer is configured to dissipate and absorb mechanical forces acting on the helmet, in order to protect the head of a person wearing the helmet. As such, the energy-absorbing layer may form the inner most layer of the helmet that is arranged closest to the head. The energy-absorbing layer particularly comprises a comparably soft material, i.e. softer than the material of the intermediate layer and/or the outer protective layer.

The energy-absorbing layer may comprise expanded polystyrol (EPS) or similar compounds or foams that provide similar properties as EPS.

It is noted that on a side facing the head of a person wearing the helmet, a lining layer or lining elements may be arranged for adjusting the fit of the helmet and or for reasons of comfort.

The energy-absorbing layer may comprise a plurality of layers, a plurality of layer elements, or it may be formed as a stack of layers that form the energy-absorbing layer.

Similarly, the intermediate and/or the protective layer may be formed from a plurality of layers, layer elements and/or a stack of layers that form the respective layer.

According to another embodiment of the invention, the outer protective layer comprises a different material than the energy-absorbing layer and/or the intermediate layer. Particularly, the intermediate layer is the stiffest and the hardest layer of the helmet.

According to another embodiment of the invention, the intermediate layer is formed and designed to provide a low-friction surface on which the outer protective layer may move in case the outer protective layer is exposed to the impact force.

Particularly, the low-friction is achieved by forming the intermediate layer harder than the outer protective layer.

The intermediate layer may comprise or consist of a polycarbonate.

The intermediate layer may be connected to the energy-absorbing layer by means of a substance-to-substance bond, e.g. it may be glued to the energy-absorbing layer, such as to be permanently attached to the energy-absorbing layer. Particularly, the intermediate layer is configured to stay attached to the energy-absorbing layer even upon an impact force that causes the deformation of the outer protective layer.

The outer protective layer is arranged on a side of the helmet that faces away from the energy-absorbing layer. As such, the outer protective layer may form the outmost layer of the helmet. The outer protective layer may be formed from a plurality of layer elements or members that may or may not be interconnected. The layer elements may be arranged stack- wise and/ or laterally shifted to form the outer protective layer.

The intermediate layer may have a thickness in the range of 0.1 mm and 10 mm. Particularly, the intermediate layer is not a lacquer or varnish layer.

Upon exposure of the impact force the outer protective layer at least partially plastically deforms. For the deformation to happen the impact force or the tangential force component may exceed a predefined threshold value.

Particularly, the outer protective layer while plastically deforming upon exposure to the impact force forming a deformation portion, another portion may stay fixed to the energy-absorbing layer.

The term “plastically” particularly refers to a deformation that essentially maintains its shape after it has been formed. In this sense, the term “plastically” may particularly be understood as an opposite to “elastically”.

According to another embodiment of the invention, the outer protective layer while plastically deforming upon exposure to the impact force forms a deformation portion that comprises a compacted or contracted portion of the outer protective layer. That is, for example, undulations or folding lines that may be formed or that may be preformed on the outer protective layer may become steeper in amplutide and/or higher in frequency upon deformation - as opposed to become more stretched out.

According to another embodiment of the invention, upon exposure to the impact force, the outer protective layer is configured to deform relative to the energy-absorbing layer.

According to another embodiment of the invention, the outer protective layer is arranged on the energy-absorbing layer or another layer that is non-plastically deformable. That is, upon impact, only the outer protective layer plastically deforms, wherein particularly layers claoser to the energy-absorbing layer or the energy absorbing layer itself remains plastically undeformed.

Particularly, energy-absorbing layer is harder than the outer protective layer.

Particularly the helmet is devoid of a fluidic or plastically deformable layer. Such fluidic layer may have a viscous, tarry consistency that upon impact absorbs the energy of the outer protective layer and plastically deforms in the process of absorbing the impact energy. Upon exposure to the impact force, it is possible that the energy-absorbing layer experiences some deformation, however the outer protective layer is configured to plastically deform relative to the energy-absorbing layer.

According to another embodiment of the invention, upon exposure to the impact force the outer protective layer may deform such that the deformed portion of the outer protective layer is not congruent anymore or incongruent with the energy-absorbing layer.

Particularly, the term “congruent” refers to the shapes of the outer protective layer and the energy-absorbing layer that are locally parallel in the intact and assembled state of the helmet. That is, the surfaces of the outer protective layer and the energy-absorbing layer that face each other in the intact and assembled state of the helmet are locally parallel, may become locally non-parallel in the deformation portion. To this extent, the term “congruent” may be understood in a mathematical fashion relating to two congruent surfaces.

The term “tangential” particularly refers to a direction extending along or parallel to a surface of the helmet. Said surface of the helmet may be a surface of the outer protective layer (before deformation).

The exposure impact force may happen during an accident where the head of the person protected by the helmet hits an object such that a tangential force component causes a shear stress on the helmet. In order to reduce the shear stress the outer protective layer is configured to plastically deform and thus to absorb a kinetic energy at least partially.

The outer protective layer may be connected to the energy-absorbing layer or the intermediate layer by means of connectors or a substance-to-substance bond.

Particularly, the connectors fail or deform upon exposure to the impact force so as to allow the outer protective layer to plastically deform relative to the energy-absorbing layer.

According to another embodiment of the invention, upon the exposure to the impact force, the tangential component of the impact force is absorbed at least partially by the outer protective layer causing the outer protective layer to plastically deform in the deformed portion. An outer protective layer having these properties are particularly well-suited to reduce a shear stress acting on a head upon impact, as it deforms at least partially in a deformed portion.

According to another embodiment of the invention, the deformed portion comprises undulations in a direction essentially orthogonal to a surface of the outer protective layer, particularly before the exposure to the impact force.

These undulations facilitate an enhanced plastically deformable surface in the deformed portion.

According to another embodiment of the invention, upon exposure to the impact force, the outer protective layer is configured to at least partially compress along a direction essentially tangential to the surface of the outer protective layer.

Such compression absorbs impact energy and thus helps to reduce a shear stress on the head.

According to another embodiment of the invention, upon exposure to the impact force, the outer protective layer is configured to at least partially thin or taper, particularly in a region where the outer protective layer is not compressed upon exposure to the impact force.

This embodiment adds to the previous embodiment in so far that not only is the outer protective layer compressed but also a thinning or tapering facilitates an absorption of the impact energy.

According to another embodiment of the invention, the deformed portion is formed by a tectonic motion of the outer protective layer upon impact, particularly such that the undulations in the deformed portion are formed.

The tectonic motion may be characterized in that the outer protective layer moves laterally with respect to the energy-absorbing layer, particularly wherein in certain areas comprised by the deformed portion the outer protective layer forms an undulating shape, which formation requires absorbing the impact energy and thus helps to reduce a shear stress on the head of a wearer of the helmet.

According to another embodiment of the invention, the outer protective layer comprises a plurality of fold lines along which undulations may be formed in the deformed portion. This embodiment allows to further improve the deformation characteristics of the helmet upon impact. The fold lines allow a defined folding characteristic of the outer protective layer, particularly by forming the undulations along at least some the fold lines.

According to another embodiment of the invention, the outer protective layer has a reduced thickness along the fold lines, such that the undulations form along said fold lines in the deformed portion.

According to another embodiment of the invention, upon exposure to the impact force, the outer protective layer is configured to deform relative to the energy absorbing layer, particularly such that deformed portion of the outer protective layer is not congruent with the energy-absorbing layer anymore.

This deformation characteristic describes a process that differs to any sliding or rupturing process that are designed to facilitate a lateral, congruent movement of the outer protective layer with respect to the energy-absorbing layer.

According to another embodiment of the invention, the outer protective layer comprises a plurality of outer protective layer members.

This embodiment allows the formation of a multi-portion outer protective layer, in which each member of the outer protective layer may plastically deform upon impact or does not deform but only alters its position with respect to the energy-absorbing layer.

According to another embodiment of the invention, the outer protective layer members are interconnected along the fold lines to form the outer protective layer.

This embodiment further elaborates on the dynamic of the members upon impact, namely that the members in essence form sections of the outer protective layer that may alter position with respect to the energy-absorbing layer along the fold lines and/or alter their shape upon impact.

Therefore, the outer protective layer may be formed by a comparably hard material particularly with low deformation properties. The plastic deformation of the outer protective layer may instead be generated by the members of the outer protective layer that fold along the fold lines, particularly wherein the members do not plastically deform. According to another embodiment of the invention, the outer protective layer members are connected by means of hinge devices that allow the outer protective layer to plastically deform relative to the energy-absorbing layer upon exposure to the impact force.

This embodiment provides similar advantages as the previous embodiment. The hinge devices may be formed by an elastic and thin connecting member that connects two adjacent outer protective layer members.

According to another embodiment of the invention, the outer protective layer members are at least partially overlapping or stacked to form the outer protective layer, wherein at portions in which the outer protective layer members are overlapping, the outer protective layer may be configured to plastically deform upon exposure to the impact force.

This embodiment allows for a flexible design of the outer protective layer in terms of its deformation characteristic. Further, particularly instead of having interconnecting hinge members or fold lines, folding locations on the outer protective layer may be defined by these overlapping portions., which is a cost-efficient way to implement the intended plastic deformation.

According to another embodiment of the invention, the deformation portion of the outer protective layer comprises undulations exhibiting irregular or varying spatial undulation frequencies.

This way, the helmet is configured to absorb impact energy of varying degrees by forming undulations of different frequencies, depending on the amount of energy to be absorbed.

Lower impact forces may lead to only a few undulations with lower spatial frequencies, as compared to higher impact forces that may lead to higher spatial frequency undulations.

According to another embodiment of the invention, a degree of deformation of the deformed portion varies locally and in dependency of a direction of the impact force.

This embodiment allows for an improved deformation characteristic that is less dependent on a direction of the impact force.

According to another embodiment of the invention, the outer protective layer comprises fixed portions in which the outer protective layer is configured to remain fixed or at least spatially constrained relative to the energy-absorbing layer, particularly wherein the outer protective layer does not deform upon exposure of the impact force relative to the energy-absorbing layer in the fixed portions.

These portions may be designed to maintain an overall deformation characteristic of the helmet to ensure that the deformation in the of the deformed portion takes place at the correct regions in the outer protective layer.

According to another embodiment of the invention, an intermediate layer is arranged between the energy-absorbing layer and the outer protective layer, particularly wherein the intermediate layer is configured to facilitate a movement of the outer protective layer upon exposure to the impact force relative to the energy-absorbing layer.

According to another embodiment of the invention, the intermediate layer is stiffer and/or harder than the energy-absorbing layer.

This allows a better deformation characteristic of the outer protective layer, as the outer protective layer is not prone to catch or cant in the energy-absorbing layer upon impact.

According to another embodiment of the invention, the intermediate layer is connected to the energy-absorbing layer by means of a substance-to-substance bond and/or by means of an interlocking connection. Such a connection may be configured to rupture upon impact.

According to another embodiment of the invention, the outer protective layer is configured to fold, crumple, and/or hinge upon exposure to the impact force.

This embodiment illustrates the various types of plastic deformation that may happen upon impact in the deformed portion.

According to another embodiment of the invention, the outer protective layer is connected to the energy-absorbing layer or the intermediate layer by means of a tethering connection, by means of a string and/or elastic bands.

According to another embodiment of the invention, the outer protective layer has a thickness in the range of 0.05 mm to 5 mm.

According to another embodiment of the invention, the outer protective layer comprises a thermoplastic or a metal.

According to another embodiment of the invention, the outer protective layer is stiff as a thermoplastic or a metal.

According to another embodiment of the invention, the energy-absorbing layer is softer than the outer protective layer. According to another embodiment of the invention, the energy-absorbing layer is arranged closer to a head of a person wearing the helmet than the outer protective layer.

This embodiment illustrates the order of layers of the helmet with respect to an inside and an outside facing side of the helmet.

The helmet according to the invention may be manufactured advantageously by means of an injection molding or a damp forming method.

Fifth aspect of the invention “Helmet with a partially detachable layer”

An object of the fifth aspect of the invention is to provide a helmet with enhanced safety features. The object is achieved by the device having the features of claim 56.

Advantageous embodiments are described in the dependent claims 57 to 84. According to the fifth aspect of the invention, a helmet comprises:

- an inner layer and

- at least one outer protective layer arranged on the inner layer, wherein under an impact force on the at least one protective layer, the at least one protective layer is configured to partially detach from the inner layer.

Preferably, said inner layer may comprise energy absorbing elements and/or an energy absorbing material, so as to form an energy absorbing layer.

According to an embodiment of the present invention, the at least one outer protective layer may comprise a plurality of stacked sub layers that may be connected to one another. The at least one outer protective layer may alternatively or additionally also comprise multiple mutually connected shell segments that are arranged essentially in a respective plane along the outer protective layer.

According to another embodiment of the present invention, the at least one protective layer may be configured to partially detach from the inner layer, particularly depending on a direction of the impact force.

According to another embodiment of the present invention, the at least one outer protective layer may be configured to partially detach from the helmet, if the impact force comprises a tangential component pointing towards a circumferential rim of the helmet, said helmet being arranged above a face of a user wearing the helmet. The tangential component of the impact force may describe a direction pointing essentially along a surface of the outer protective layer.

According to another embodiment of the present invention, the at least one outer protective layer may be configured to remain attached to the helmet if the impact force comprises a tangential component pointing away from the circumferential rim of the helmet arranged above the face of the user wearing the helmet.

In another embodiment of the present invention, the at least one protective layer may comprise a first portion and a second portion, said first and second portion being integrally connected to each other, wherein the first portion is permanently connected to said inner layer, while said second portion is configured to detach under an impact force.

For example, the at least one outer protective layer may partially fracture so as to partially detach from the helmet.

In another embodiment of the present invention, said at least one outer protective layer may comprise a first portion and a second portion, wherein said first portion is permanently connected to said inner layer and wherein under an impact force, said second portion is configured to detach under an impact force and lock with said first portion. By locking said second with said first portion, the outer protective layer remains secured to the helmet via said first portion upon an impact.

In another embodiment of the present invention, said first portion may comprise a rotating connector and/or a hinge.

By using a rotating connector and/or a hinge, the desired partial detachment of said second portion of the at least one outer protecting layer integrally connected to said first portion may be realized in a cost-efficient and structurally straight-forward way.

In another embodiment of the present invention, the first portion may be at least partially arranged inside inner layer. To that end, the surface of the inner layer may for example comprise at least one opening, wherein the at least one outer layer may be guided into the at least one opening so as to be arranged at least partially inside inner layer. With this specific arrangement, the at least one outer player and particularly said first portion may be attached to the helmet in a cost-efficient and simple way. In another embodiment of the present invention, the at least one outer protective layer may be permanently attached to the inner layer in the circumferential rim area of the helmet arranged above the face of the user wearing the helmet.

In particular, the at least one outer protective layer is configured to remain attached to the inner layer upon an impact on the at least one outer protective layer, so as to prevent the outer protective shell from moving into the face of the user wearing the helmet, possibly causing severe injuries to the user. Said circumferential rim area may also refer to areas close to the neck of the user, so as to prevent the outer protective layer from moving into the neck upon an impact.

According to another embodiment of the present invention, the helmet may additionally comprise an intermediate layer arranged between the inner layer and the at least one outer protective layer.

Analogous to the at least one outer protective layer, the intermediate layer may also comprise a plurality of stacked sub layers and/or mutually connected shell segments that are arranged essentially in a respective plane of the intermediate layer.

In another embodiment of the present invention, the at least one protective layer and/or the intermediate layer may be attached to said helmet using connectors, particularly adhesive and/or by tethering, particularly by means of strings and/or elastic bands.

According to another embodiment of the present invention, the intermediate layer may be configured such that a coefficient of friction between the intermediate layer and the at least one outer protective layer and/or a coefficient of friction between the intermediate layer and the inner layer is lower than a coefficient of friction between the at least one outer protective layer and the inner layer.

The coefficient of friction between the intermediate layer and the at least one outer protective layer and/or the coefficient of friction between the intermediate layer and the inner layer may be for example less than 0.3.

As such, the intermediate layer may constitute a low friction layer that promotes a movement of the at least one outer protective layer relative to the inner layer, so as to at least partially adsorb harmful rotational forces for the head and neck of a user occurring upon an impact. Said means to facilitate the movement of the at least one outer protective layer relative to the inner layer upon an impact force may also include elements to reduce the friction between the at least one outer protective layer and the inner layer.

As an example, said intermediate layer may comprise Tollable elements, such that the at least one outer protective layer moves relative to the intermediate layer and the inner layer upon an impact, wherein if the impact force comprises a tangential component pointing towards the circumferential rim of the helmet arranged above the face of the user wearing the helmet, said first portion of the at least one outer protective layer is configured to remain attached to the helmet and wherein the second portion of the at least one outer protective layer is configured to detach from the intermediate layer and the inner layer.

By keeping the at least one outer protective layer attached to the helmet at said first portion, a harmful movement of the outer protective layer into the face of the user is prevented in case the impact force comprises a tangential component directed towards the circumferential rim of the helmet arranged above the face of the user wearing the helmet. At the same time, the outer protective layer may be configured to completely detach from the helmet in case the impact force comprises a tangential component directed away from the circumferential rim of the helmet, for example towards a top area of the helmet. In this case, the outer protective layer and particularly said second portion may for move, shear or stretch along the tangential force direction. A fracture of the first and second portion may also occur so as to completely detach the second portion from the helmet.

In any impact scenario, the at least one outer protective layer is preferably configured to move relative to said inner protective layer, so as to at least partially adsorb harmful rotational forces for the head and neck of a user occurring upon an impact

In another embodiment of the present invention, said intermediate layer may comprise at least one element that is configured to fail under on impact force on the at least one outer protective layer, wherein upon said failure of said element, said at least one outer protective layer is configured to move relative to said intermediate layer, wherein if the impact force comprises a tangential component pointing towards the circumferential rim of the helmet arranged above the face of the user wearing the helmet, said first portion of the at least one outer protective layer is configured to remain attached to the helmet and wherein the second portion of the at least one outer protective layer is configured to detach from the intermediate layer and the inner layer. As such, the intermediate layer may constitute a reactive layer that changes for example the mechanical properties of the system comprising the at least one outer protective layer, the intermediate layer and the inner layer upon impact. Preferably, said mechanical properties are changed such that a movement of the at least one outer protective layer, the intermediate layer and the inner layer relative to each other is facilitated upon an impact.

In another embodiment of the present invention, said Tollable elements may comprise or be at least one of the following: balls, beads, rolls.

In another embodiment of the present invention, said Tollable elements may comprise a circular diameter between 0.1 mm and 4 mm, particularly between 1 mm and 2 mm.

Said circular diameter may refer to a circular cross-section of said Tollable elements.

In another embodiment of the present invention, the intermediate layer may be fixed and/or suspended to the inner layer.

In another embodiment of the present invention, said at least one outer protective layer may be integrally formed with the inner layer, making the fabrication of the two layers fast and cost-efficient.

In another embodiment of the present invention, the at least one outer protective layer may comprise relief cuts so as to facilitate the partial detachment of said at least one protective layer.

By adjusting the geometry and the distribution of the relief cuts along the outer protective layer, the partial detachment and particularly the threshold force of the tangential force component required for partial detachment may be varied.

In another embodiment of the present invention, the second portion of the at least one outer protective layer may be configured to partially detach from said helmet, if the tangential component of the impact force exceeds a predetermined threshold force, particularly a threshold force exceeding 0.5 kN.

For example, the threshold force required for the partial detachment of the at least one outer protective layer may increase or decrease with a distance from the circumferential rim of the helmet. In another embodiment of the present invention, said predetermined threshold force may vary as a function of the impact force direction and/or a position of the impact within the at least one outer protective layer.

In another embodiment of the present invention, the at least one outer protective layer may be configured to fold and/or hinge and/or crumple upon an impact.

In another embodiment of the present invention, an amount of detachment of the second portion of the at least one outer protecting layer may vary as a function of at least one of the following: the impact force direction, the tangential component of the impact force and the position of the impact on the at least one outer protective layer.

In another embodiment of the present invention, the at least one outer protective layer may comprise a material that is harder than a material comprised by the inner layer.

In another embodiment of the present invention, the at least one outer protective layer may comprise a thermoplastic and/or a metal.

In another embodiment of the present invention, the inner layer may comprise styrene and/or polystyrene.

In another embodiment of the present invention, the at least one outer protective layer may comprise a thickness within 0.05 mm and 5 mm.

If the at least one outer protective layer is formed by a plurality of stacked shells, said thickness may refer to a total thickness of all stacked shells forming the at least one outer protective layer.

Figure Description with exemplary embodiments

Particularly, 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 said text of the Figures may be incorporated (also in an isolated fashion) into a claim relating to the device according to the present invention. Fig. 1 schematically shows the layer structure of the helmet according to the invention;

Fig. 2 schematically shows another embodiment of the helmet;

Fig. 3 schematically shows a manufacturing process of the helmet.

Examples relating to the first, second, and third aspect of the invention

Figures 1 to 3 show schematical cross-section through a portion of the helmet 1-1 according to the first or third aspect.

Figs 1 and 2 show the layer structure of the helmet 1-1 according to the first aspect of the invention. The outer protective layer 1-2 is attached to the helmet 1-1 by means of connector elements 1-5 that extend from the energy-absorbing layer 1-4 through openings in the intermediate layer 1-3.

According to the exemplary embodiment in Fig. 1A the connector elements 5 are directly connected to the outer protective layer 1-2, wherein according to the exemplary embodiment shown in Fig. 1B, the connector element 1-5 are connected by means of broadening elements 1-6, that broaden a contact area between the connector elements 5 and the outer protective layer 1-2.

The connector elements 1-5 are integrally formed with the energy-absorbing layer 1- 4, wherein the energy-absorbing layer 1-4 is made from a softer material, e.g. expanded polystyrene than the outer protective layer 2 and the intermediate layer 1- 3.

Upon exposure of an impact force the connector elements 1-5 may rupture, particularly at predefined rupture portions so as to release the outer protective layer 1-2 and reduce the shear stress on the head of a person wearing the helmet 1-1.

The connector elements 1-5 may have different circumference as can be seen in comparison of Fig. 1 with Fig. 2. Which allows a tuning of the predefined force upon which the outer protective layer 2 becomes disconnected form the helmet 1-1.

In Fig. 3 a helmet 1-T according to the third aspect of the invention is shown, wherein the outer protective layer 1-2’ at a rim portion 1-1 T of the helmet 1-T is interlocked in the energy-absorbing layer 1-4’. For this purpose, the outer protective layer 1-2’ comprises interlocking elements 1-10’ that extend around the intermediate layer 1-3’ and enclose the intermediate layer 1-3’ while protruding into the energy absorbing layer 1-4’. Upon impact, the interlocking elements 1-10’ may deform or rupture, in general fail, such as to release the outer protective layer 1-2’ from the energy-absorbing layer 1-4’ in order to reduce the shear stress on the helmet 1-1’.

The interlocking elements 1-10’ are formed integrally with the outer protective layer 1 2

Examples relating to the fourth aspect of the invention

In the following, some features that are optional and that may be combined with each other are listed in the following:

- the outer protective layer can be formed by a plurality of outer protective layer members and/or stacked members;

- a degree of release of the members can be directionally dependent

- the protective layer can be partially fixed/constrained to the energy-absorbing layer at points or in predefined areas of the helmet;

- an intermediate layer can be placed between the outer protective layer and the energy absorbing layer;

- the outer protective layer is configured to fold, hinge and/or crumple in the in-plane direction, wherein said in-plane direction extends a parallel to a surface of the energy-absorbing layer that faces toward the outer protective layer;

- the outer protective layer can be constrained to the energy absorbing or intermediate layer, for example by tethering facilitated e.g. by a string, and/or an elastic band.

- the intermediate layer can be fixed to the energy absorbing layer or suspended;

- the intermediate layer can be a low friction layer.

Fig. 4 schematical drawing of the outer protective layer before and after plastic deformation

Fig. 5 schematically shows hinge devices or hinges in the outer protective layer

Fig. 6 schematically shows an undulated outer protective layer; Fig. 7 schematically shows a helmet having an outer protective layer of varying thickness; and

Fig. 8 shows a motorcycle helmet according to the fourth aspect of the invention.

In Fig. 4A shows a cross-sectional view of the outer protective layer 2-1 in an undeformed state. The remainder of the helmet is not shown, but would extend along a downward facing side 2-13 of the outer protective layer 2-1. The outer protective layer is made from a material that is comparably stiff and does not tend to plastically deform upon exposure to an impact force but to maintain its shape. In order to allow the outer protective layer 2-1 to fold and therefore plastically deform upon impact, the outer protective layer 2-1 comprises a plurality of fold lines 2-11, 2-12 that subdivide the outer protective layer 2-1 in a plurality of interconnected outer protective layer members 2-1a, 2-1 b, 2-1c. The fold lines 2-11, 2-12 are in essence recesses in the outer protective layer 2-1 along which the outer protective layer members may allow the outer protective layer 2-1 to fold. The outer protective layer 2-1 has fold lines 2-11 that are formed on a first side 2-14 of the outer protective layer 2-1 and fold lines 2- 12 that extend on a second side 2-13 of the outer protective layer 2-1, wherein said second side 2-13 faces in the opposite direction than the first side 2-14, such that an undulation of the outer protective layer 2-1 is achieved upon exposure of an impact force 2-F. Upon exposure of the outer protective layer 2-1 to a tangential impact force (indicated by the arrow 2-F), i.e. a force that has at least a component along an extension direction of the outer protective layer 2-1, the outer protective layer members 2-1a, 2-1 b, 2-1c are tectonically shifted with respect to each other, such that the outer protective layer adopts an undulation shape in the deformed portion 10 of the outer protective layer 2-1. The fold lines 2-1 a, 2-1 b, 2-1 c define the undulation by way of their location on the outer protective layer 2-1. The outer protective layer therefore absorbs the impact force 2-F by plastically deforming an undulating shape along the fold lines 2-1a, 2-1 b, 2-1c.

Fig. 5A schematically shows various types of fold lines 2-12, 2-12’, 2-12” arranged on the second side 2-13 of the outer protective Iayer2-1. Each kind of fold line 2-12, 2-12’, 2-12” may provoke a different folding behavior of the outer protective layer.

Each type of fold line may be arranged on each side of the outer protective layer 2-1. It is also possible to have different types of fold lines 2-12, 2-12’, 2-12” on the same side 2-13, 2-14, or different sides 2-13, 2-14 of the outer protective layer 2-1. Fig. 5B schematically shows an exemplary embodiment having a plurality of fold lines 2-12 on the first 2-14 and the second side 2-13 of the outer protective layer 2-1, wherein the fold lines are arranged pairwise opposite of each other. This allows a folding of the outer protective layer 2-1 that may also lead to a compression and/or thinning of the outer protective layer along an extension direction exhibiting a concertina effect.

Fig. 6 schematically shows a cross-sectional view of a helmet 2-10 comprising plastically deformed outer protective layer 2-1 that adopts an undulating shape over the surface of the helmet 2-10 as a result of a tangential impact force (not shown) to which the outer protective layer 2-1 has been exposed. The deformed portions 2-101, 2-102 of the outer protective layer 2-1 may be subdivided in a portion 2-101 in which the undulation has a lower spatial frequency as in an adjacent deformation portion 2- 102. This is indicated by the period 2-x” and 2-x’ respectively of the undulation. In between the two deformation portions 2-101, 2-102 the outer protective layer may be fixedly attached to an energy-absorbing layer 2-2 of the helmet.

The outer protective layer 2-1 has been plastically deformed and has no fold lines or hinge devices. However, the same result can be achieved with fold lines and/or hinge devise incorporated in the outer protective layer 2-1.

The helmet 2-10 further comprises the energy-absorbing layer 2-2 that is arranged on the second side of the outer protective layer and thus closer to the head (not shown) of a wearer of the helmet 2-10. As can be seen upon exposure of an impact force the outer protective layer 2-1 has been plastically deformed in two deformation portions 2-101, 2-102 and is not elastically relaxing into a previous (intact) state after exposure. The plastic deformation occurs relative to the energy-absorbing layer 2-2, i.e. a shape and geometry of the energy-absorbing layer 2-2 essentially remains unaltered.

In Fig. 7 a schematic cross-sectional view of two exemplary embodiments of the outer protective layer 2-1 are depicted. In Fig. 7 A the outer protective layer 2-1 has three regions 2-200, 2-201, 2-200 of different thickness, i.e. the outer protective layer 2-1 has a tapered thickness. This allows for a varying plastic deformation characteristic along the different regions 2-200, 2-201 , 2-202 of varying thickness.

Similarly, in Fig. 7B, an embodiment of the outer protective layer 2-1 is shown that continuously changes its thickness, rather than stepwise as in Fig. 7A. In Fig. 8 a schematic view of an energy-absorbing layer 2-2 of a helmet 10, particularly a motorcycle helmet, is shown that has an outer protective layer 2-1 layout similar to the outer protective layer 2-1 design is depicted in Fig. 7A. The outer protective layer 2-1 has a thin portion 2-200 at a front portion of the helmet 2-10 and a thick portion 2-202 of the outer protective layer 2-1 at a back of the head portion of the helmet 2-10. The outer protective layer 2-1 allows for plastic deformation in the thin portion 2-200 of the outer protective layer 2-1 that results already at a lower impact force as the deformation at the thick portion 2-202 of the outer protective layer 2-1.

Examples relating to the fifth aspect of the invention

Fig. 9 shows an embodiment of the helmet according to the invention, wherein und an impact force on the at least one protective layer, the at least one protective layer is configured to partially detach from the inner layer.

Fig. 10 schematically shows an embodiment of a layer structure of a helmet according to the invention; wherein at least one outer protective layer of the helmet is configured to partially detach from or remain attached to the helmet, depending on a direction of the impact on the at least one outer protective layer.

Fig. 11 schematically shows an embodiment of a locking mechanism keeping the at least one outer protective layer connected to the helmet via a first portion while detaching from the helmet with a second portion.

Fig. 12 shows an embodiment of the helmet with different impact directions indicated by arrows.

Fig. 13 shows an embodiment of the helmet and an exemplary layer structure with encircled areas indicating areas where the at least one outer protective layer remains attached to the helmet.

Figs. 14 A, B shows the advantage of a helmet according to the invention (B) over a prior art helmet (A).

Figs. 15 A-C show schematics of reliefs cuts arranged on the helmet used so as to facilitate the partial detachment of the protective layer. Figs. 16 A, B shows schematics of a rotating connector (A) or a hinge (B) that may be used for the partial detachment of the at least one outer protective layer.

Fig. 9 shows a schematical cross sectional view of an embodiment of the layer structure for a helmet 3-1 according to the invention.

According to the invention, the helmet 3-1 comprises at least an inner layer 3-2 and at least one outer protective layer 3-3, wherein under a local impact force 3-F, the protective layer is configured to partially detach from the helmet 3-1.

In Fig. 9, the local impact force 3-F is illustrated by means of an arrow on the top figure. From top the bottom, the series of figures demonstrates how the at least one outer protective layer 3-3 partially detaches from the helmet 3-1 upon impact.

The inner layer 3-2 is preferably arranged closer to a user’s head than the at least one outer protective layer 3-3, such that the at least one outer protective layer 3-3 is affected first in case of an impact. The at least one outer protective layer 3-3 may for example comprise a thickness within 0.05 mm and 5 mm.

Both the inner layer 3-2 and the at least one outer protective layer 3-3 may comprise or consist of a plurality of shells. The plurality of shells may be formed by multiple individual shells connected to one another. Said individual shells may be arranged essentially in a plane but they may also be arranged on top of each other, forming stacked shells or stacked sub-layers.

The at least one outer protective layer 3-3 may be configured to partially detach from said helmet 3-1 beyond a predetermined threshold force upon a local impact, in particular beyond a tangential threshold force along said first direction. Said threshold force may be around 0.5 kN.

In another embodiment, still referring to Fig. 9, the helmet 3-1 may additionally comprise an intermediate layer 3-6, said intermediate layer 3-6 being preferably arranged between the inner layer 3-2 and the at least one outer protective layer 3-3.

The intermediate layer 3-6 may comprise Tollable elements 3-7, such that the at least one outer protective layer 3-3 may move relative to the intermediate layer 3-6 and the inner layer 3-2 upon an impact. The Tollable elements 3-7 may be balls, beads, rolls and the like. As such, the intermediate layer 3-6 may facilitate a relative movement between the at least one outer protective layer 3-3 and the inner layer 3-2. The intermediate layer 3-6 may also comprise at least one element (not shown in Fig. 9) that is configured to fail under on impact force 3-F on the at least one outer protective layer 3-3, wherein upon said failure of said element, said at least one outer protective layer 3-3 is configured to move relative to said intermediate layer 3-6, wherein if the impact force 3-F comprises a tangential component pointing towards the circumferential rim 3-4 of the helmet 3-1 arranged above the face of the user wearing the helmet 3-1, said first portion 3-11 of the at least one outer protective layer 3-3 is configured to remain attached to the helmet 3-1 and wherein the second portion 3-12 of the at least one outer protective layer 3-3 is configured to partially detach from the intermediate layer 3-6 and the inner layer 3-2.

As such, the intermediate layer 3-6 may constitute a reactive layer that changes for example the mechanical properties of the system comprising the at least one outer protective layer 3-3, the intermediate layer 3-6 and the inner layer 3-2 upon impact. Preferably, said mechanical properties are changed such that a movement of the at least one outer protective layer 3-3, the intermediate layer 3-6 and the inner layer 3-2 relative to each other is facilitated upon an impact.

In another embodiment of the present invention, shown in Fig. 10, the at least one protective layer is configured to detach from the helmet 3-1 depending on a direction of the impact force 3-F, particularly depending on a tangential component of the impact force 3-F being directed essentially along a surface of the at least one outer protective layer 3-3. In this scenario, a second portion 3-12 of the at least one outer protective layer 3-3 may peel off the helmet 3-1 while remaining attached to the helmet 3-1 with a first portion 3-11 of the outer protective layer 3-3. A partial detachment or peeling of the helmet 3-1 is particularly useful to prevent the at least one outer protective layer 3-3 and/or said Tollable elements 3-7 from moving into the face or neck of a user wearing the helmet 3-1 , particularly if the impact force 3-F is directed towards the face or neck.

According to another aspect of the present invention, also shown in Fig. 10, the at least one outer protective layer 3-3 may be configured to move relative to the intermediate layer 3-6 and/or the inner layer 3-2, so as to at least partially absorb harmful rotational forces for the head and neck of the user occurring upon impact. To this end, the at least one outer protective layer 3-3 may also shear or stretch along the tangential direction of the impact force 3-F. The outer protective layer 3-3, and particularly said second portion 3-12 of the outer protective layer 3-3 may also rupture so as to completely detach from said helmet 3-1, in case the tangential impact force 3-F direction is not directed towards the face and/or the neck of the user in order to maintain the rotational performance of the helmet 3-1 upon impact.

As shown in Fig. 10, the at least one outer protective layer 3-3 may be configured to move over the intermediate layer 3-6 and the inner layer 3-2 upon an impact with a tangential force component pointing in a first direction, while being configured to detach from the helmet 3-1 upon an impact with a tangential force component pointing in a second direction. In this example, the first direction and the second direction are opposite to each other. Said first direction may point to a circumferential rim 3-4 of the helmet 3-1, particularly to a circumferential rim 3-4 arranged above the face of the user. Said second direction may be opposite to said first direction and point to a top area of the helmet 3-1 , i.e. away from the circumferential rim 3-4 of the helmet 3-1.

As shown in Fig. 10, the at least one outer protective layer 3-3 may be partially arranged below the inner layer 3-2 so as to attach said at least one outer protective layer 3-3 to said helmet 3-1. This may be done in the circumferential rim 3-4 area of the helmet 3-1. To this end, the surface of the inner layer 3-2 may for example comprise at least one opening, wherein the at least one outer layer may be guided into the at least one opening so as to be arranged at least partially below the surface of the inner layer 3-2. Alternatively or additionally, the at least one outer protective layer 3-3 may be permanently attached to said helmet 3-1 using connectors, particularly adhesive and/or by tethering, particularly by means of strings and/or elastic bands.

Said intermediate layer 3-6 may also be comprised in the embodiments described above, such that the at least one outer protective layer 3-3 may be configured to partially detach from or to move relative to the intermediate layer 3-6 and the inner layer 3-2, depending on the direction of the impact.

Fig. 11 schematically shows a locking mechanism that may be used to keep said at least one outer protective layer 3-3 connected to the helmet 3-1 via the first portion 3- 11 while the second portion 3-12 is configured to detach from the helmet 3-1. For example, as shown in Fig. 11, said first portion 3-11 may be buried inside the inner layer 3-2 so as to remain permanently attached to the helmet 3-1. Alternatively, said first portion 3-11 may also be permanently fixed to the helmet 3-1 using adhesion, tethering or the like. The first portion 3-11 may further serve as a lock for said second portion 3-12 to avoid a complete detachment of the at least outer protective layer 3-3 upon an impact, particularly if the impact direction is directed to the circumferential rim 3-4 arranged above the face of the user. This may be realized by an opening of the first portion 3-11 with a first diameter, wherein said second portion 3-12 is configured to slide through said opening upon an impact force 3-F until a locking element 3-9 with a second diameter larger than said first diameter is reached, so as to lock said first and second elements. Other locking mechanisms, particularly mechanical locking mechanisms, for example using other geometries of said first and second portions 3-11,3-12 resulting in a locking of said first and second portion 3- 11,3-12 are likewise possible.

Fig. 12 shows a view of an embodiment of the helmet 3-1 with arrows indicating different directions of impact force 3-Fs caused by an impact. As stated above, the at least one outer protective layer 3-3 of the helmet 3-1 may be configured to partially detach from the helmet 3-1 , depending on the direction of the tangential component of the impact force 3-F, said tangential component being directed essentially along the surface of the at least one outer protective layer 3-3.

Fig. 13 shows a view of another embodiment of the helmet 3-1, with a section of an exemplary layer structure presented in an explosion view. From the inside to the outside, the helmet 3-1 may comprise an inner layer 3-2, an intermediate layer 3-6 and at least one outer protective layer 3-3. The at least one outer protective layer 3-3 may be covered with lacquer or varnish. Said intermediate layer 3-6 may comprise Tollable elements 3-7, such as balls, beads, rolls and the like, so as to facilitate relative movement of the at least one outer protective layer 3-3 and the inner layer 3-2 upon an impact.

The at least one outer protective layer 3-3 may be permanently and permanently connected to the helmet 3-1 at a lower edge area of the helmet 3-1, e.g. by partially arranging it below the inner layer 3-2 and/or by using connectors, particularly adhesive and/or by tethering, particularly by means of strings and/or elastic bands.

Figs. 14 A, B demonstrate the advantage of the present invention compared to the prior art.

Fig. 14A shows an impact test of a dummy wearing a prior art helmet 3-1 equipped with at least one outer protective layer 3-3 that is configured to move relative to the inner layer 3-2 so as to minimize a harmful rotational movement of head and neck upon impact. As can be seen, for the present impact direction, the at least one outer protective layer 3-3 moves into the facial area of the user, possibly causing severe injuries due to the lose at least one outer protective layer 3-3.

Fig. 14B shows an impact test of a dummy wearing a helmet 3-1 according to the invention. While the present helmet 3-1 likewise allows a movement of the at least one outer protective layer 3-3 relative to the inner layer 3-2 so as to minimize a harmful rotational movement of head and neck upon impact, the advantageous attachment of the at least one outer protective layer 3-3 to the helmet 3-1 with at least the first portion 3-11, for example on a lower edge are of the helmet 3-1, prevents the at least one outer layer from becoming lose and cause injuries to the user. The attachment additionally prevents the Tollable elements 3-7 that may be comprised by an optional intermediate layer 3-6 arranged between the at least one outer protective layer 3-3 and the inner layer 3-2 from being ejected into the facial area of the user.

Figs. 15 A-C show schematics of relief cuts 3-8 comprised by the protective layer that may facilitate the partial detachment of said protective layer. The geometry of the relief cuts 3-8 may be varied in order to realize a desired local detachment behavior, in particular a local detachment beyond a predetermined threshold of the tangential impact force 3-F.

Figs. 16 A,B show a rotating connector 3-5 (Fig. 16A) or a hinge (Fig. 16B) that may be used for the partial detachment of the at least one outer protective layer 3-3. Said rotating connector 3-5 or hinge may be comprised by said first portion 3-11 of said outer protective layer 3-3.

As Fig. 16A suggests, a rotating connector 3-5 may be arranged at an edge area of the helmet 3-1 , particularly at the circumferential rim 3-4 of the helmet 3-1. Depending on the impact direction, said at least one outer protective layer 3-3 may partially detach from the helmet 3-1. For instance, in case the impact direction comprises a tangential direction directed towards the circumferential rim 3-4 of the helmet 3-1 (as shown in Fig. 16A), said rotating connector 3-5 may be used to promote the partial detachment of the at least one outer protecting layer. To this end, the rotating connector 3-5 may comprise a flexible L-shaped element that pushes the at least one outer protective layer 3-3 towards the inner layer 3-2 in the absence of an impact force 3-F, wherein said rotating connector 3-5 and particularly said flexible L-shaped element may partially open so as to allow for a partial detachment of the at least one outer protective layer 3-3 while keeping the latter connected to the helmet 3-1 via said first portion 3- 11. Likewise, as shown in Fig. 16B, the mechanism described in Fig. 16A may also be realized by a hinge comprised by said first portion 3-11 , wherein the hinge allows for a rotation of the outer protective layer 3-3 around a rotational axis. Upon an impact force 3-F comprising a tangential direction directed towards the circumferential rim 3-4 of the helmet 3-1, said hinge may rotate the at least one outer protective layer 3-3 and particularly said second portion 3-12 of the at least one outer protective layer 3-3 so as to partially release the latter from the helmet 3-1, while keeping the at least one outer protective layer 3-3 attached to the helmet 3-1 with said first portion 3-11 comprising the hinge.