Classifications

• • A—HUMAN NECESSITIES
  • A42—HEADWEAR
  • A42B—HATS; HEAD COVERINGS
  • A42B3/00—Helmets; Helmet covers ; Other protective head coverings
  • A42B3/04—Parts, details or accessories of helmets
  • A42B3/06—Impact-absorbing shells, e.g. of crash helmets
• • A—HUMAN NECESSITIES
  • A42—HEADWEAR
  • A42B—HATS; HEAD COVERINGS
  • A42B3/00—Helmets; Helmet covers ; Other protective head coverings
  • A42B3/04—Parts, details or accessories of helmets
  • A42B3/06—Impact-absorbing shells, e.g. of crash helmets
  • A42B3/062—Impact-absorbing shells, e.g. of crash helmets with reinforcing means
  • A42B3/063—Impact-absorbing shells, e.g. of crash helmets with reinforcing means using layered structures
  • A42B3/064—Impact-absorbing shells, e.g. of crash helmets with reinforcing means using layered structures with relative movement between layers
• • A—HUMAN NECESSITIES
  • A42—HEADWEAR
  • A42C—MANUFACTURING OR TRIMMING HEAD COVERINGS, e.g. HATS
  • A42C2/00—Manufacturing helmets by processes not otherwise provided for

Definitions

• the invention relates to the field of health protection, specifically to a helmet for protecting the head from injury capable of absorbing also rotational forces generated during a fall, such as helmets for motorists, cyclists, and others.
• Head injuries are a major danger when practicing motor, cycling, equestrian, or other sports.
• Statistics show that a high-quality and properly fitted helmet reduces the risk of fatal injury by almost 40 % for motorcyclists, and in case of severe injury even more than 70 %. About 37 % of the cyclists killed would have survived had they been using a helmet properly.
• One variant may be a helmet according to the application US20200022443 A1.
• the inner part is suspended on strips on the outer part, which however allows movement of the parts only at a certain angle and range and does not guarantee effective dissipation of forces during impact.
• EP2854584 A1 describes a helmet with a central layer of honeycomb material which, in the event of an impact, is capable of absorbing both linear and rotational forces, but only through deformation of the material, or destruction of the helmet, and not through the relative movement of the inner and outer layers of the helmet.
• Another variant may be a helmet according to US20140208486 A1 or US9439469 B2 that comprises shock absorbers between the inner and outer layers formed of elastic materials such as rubber parts or springs. All these connections between the inner and outer layers absorb the impact force by means of connectors based on soft elastic absorbers by deforming the material. The connector thus transmits the shear stress itself, although it absorbs it to a certain extent.
• the EPS layer cannot deform properly due to its high density. This problem has already been solved by implementing multiple EPS layers, but this still does not solve the angular impacts that cause the rotational movement.
• a helmet with a multidirectional suspension system comprising an outer helmet shell and an inner helmet shell and at least three suspension connectors, where each suspension connector comprises two opposite parts, wherein a first part of the suspension connector is connected to the first one of the inner helmet shell or the outer helmet shell and a second part of the suspension connector is connected to the second one of the inner helmet shell or the outer helmet shell, wherein each part of the suspension connector comprises a base and at least one bracket extending therefrom in a direction towards the base of the opposite part, where the bases are connected by at least three flexible suspensions and the tops of the brackets are connected by at least one flexible suspension, wherein the top of the bracket of the first part is closer to the base of the second part than the top of the bracket of the second part, wherein the length of the flexible suspensions is adapted such that the flexible suspensions are in a tensioned state. From a physical point of view, it is clear that all the flexible suspensions must be in a tensioned state for the suspension connector to function.
• Each part of the connector comprises a base and a bracket, wherein the first end of the bracket is connected to the base and the second end extends out from the base and is terminated by the top of the bracket.
• the bracket is an elongated element that can be thought of as an arm or beam.
• the base may take various shapes, wherein preferably it is a shape having a round plan, a convex surface towards the outer shell of the helmet and a concave surface towards the inner shell of the helmet. Other base shapes can be used, such as a triangle or another polygon, oval, etc., wherein the base surfaces may be flat or slightly convex or concave.
• Prestressing of the tensile elements by force ensures tractive forces in all loaded states while the structure remains elastic.
• the forces are absorbed by the flexibility and/or elasticity of the suspension and, if the limit force is exceeded, by the destruction of the entire connector.
• the tensegrity connector allows for wider movement between the outer and inner shell, while at the same time it can dissipate linear impacts to a certain extent by stretching the flexible suspensions in the suspension connectors.
• a tensegrity-based helmet is the solution for the new helmet standards, where the helmet should induce an angular acceleration of less than 5000 rad/s 2 at an angular impact of 5 m/s with BrIC (brain injury criterion; a parameter indicating the probability of a severe brain injury based on the angular velocity and acceleration applied in the accident) of less than 0,6, but at the same time, for linear impacts of 5,2 m/s, the HIC (head injury criterion; a parameter indicating the probability of a severe head injury based on the time and forces applied in the accident) it should not exceed 2400.
• the indirect connection between the inner and outer shell allows the outer shell to rotate independently before the movement is transferred to the inner shell and subsequently to the head and brain in the event of a tangential impact.
• the indirect connection is realized by a special helmet structure where the inner and outer shells are connected only by tensegrity connectors and at least one of the rigid parts of the helmet is not attached to the soft central part. This feature allows relative rotation between the outer and inner layers of the helmet, provided that the individual parts of the helmet are at least similar in shape. At the same time, the connectors hold the structural integrity of the helmet. This connection reduces the rotational acceleration of the head when it hits an obstacle.
• One of the advantages of the present invention is the possibility of using the system in virtually any type of helmet, since the use of the suspension system by means of tensegrity connectors does not require the exact spherical shape of the individual parts of the helmet as is the case with prior art variants.
• a central part of soft material adapted to absorb the impact forces comprising pockets for the suspension connectors, wherein the central part is rigidly connected to the inner shell of the helmet or to the outer shell of the helmet.
• This layer has the potential to improve the dissipation of the linear force components acting on the user’s head in the event of an accident.
• the central part is most often made of a layer of expanded polystyrene with pockets for the suspension connectors, wherein the pockets are wider compared to the suspension connectors to allow movement between the inner and outer shell of the helmet.
• the flexible suspensions connecting the bases of the suspension connector are anchored at the edge of the bases, wherein by the edge of the base is meant any point on the base surface the distance of which from the connector axis is greater than 70 % of the shortest distance from the connector axis to the edge of the base surface, thus achieving the balancing of the tensile forces within the connector and thus maximum stability of the connector.
• the procedure for assembling a connection between the inner and outer shell of the helmet comprises, first of all, the step of manufacturing the suspension connector, which comprises firstly manufacturing the first and second parts of the suspension connector and then connecting the first and second parts of the suspension connector by means of flexible suspensions, within which the stress of the suspensions is also adjusted, thereby completing the suspension connector.
• a suitable way of manufacturing them is, for example, 3D printing, which allows for the manufacture of more complex structures.
• the steps of manufacturing the suspension connector are repeated depending on the number of suspension connectors needed to make the helmet.
• the first bases of the suspension connectors are rigidly connected to the first one of the inner shell of the helmet or the outer shell of the helmet.
• the connection is realized by a glue, fusion, or suitable fasteners.
• the second shell of the helmet is then positioned and the second bases of the suspension connectors are rigidly connected to the second one of the inner shell of the helmet or outer shell of the helmet, again by means of a glue, fusion, or other suitable fasteners.
• the glue can be applied either to the bases of the connectors or to the appropriate areas of the shell of the helmet. From a functional point of view, it is irrelevant whether the connector is first connected to the inner or outer shell. However, the shape of the helmet can be a limiting factor, where, for example, in the case of integral helmets it is possible that the inner shell with the connectors applied could not be inserted into the outer shell due to the dimensions of the individual parts.
• the manufacturing procedure includes the steps of applying the central part of the helmet before the step of connecting the first bases of the suspension connectors to the first one of the inner shell of the helmet or the outer shell of the helmet, where models simulating the shape of the suspension connectors adapted to define the space for the suspension connectors at the areas where the real connectors will subsequently be located are placed on the inner shell of the helmet or the outer shell of the helmet, and, for example, EPS or other material of the central part of the helmet is applied.
• the application is done by spraying or applying a fluid material, which is then cured or hardened with appropriate agents.
• the models have the same shape as the connector with adequate clearance to allow the real connector to move as desired.
• the size of the difference between the width of the connector model and the width of the real connector depends on the set stiffness of the suspension, the length of the suspension, and the stiffness of the individual parts of the connector. After application or curing of the central part, the connector models are removed and the procedure as described above continues.
• the central part of the helmet is connected to the inner shell of the helmet or the outer shell of the helmet using gluing, fusion, or fasteners before the step of connecting the first bases of the suspension connectors to the first one of the inner shell of the helmet or the outer shell of the helmet.
• fig. 1 shows a vertical section through a helmet without the suspension connectors of this invention
• fig. 2 shows a front view of the inner shell of the helmet with the suspension connectors
• fig. 3 shows a vertical section through the helmet with the suspension connectors
• fig. 4 shows a suspension connector in an embodiment with one bracket on each part of the connector
• fig. 5 shows a suspension connector in an embodiment with three connected brackets on each part of the connector.
• the basic embodiment is a helmet for motorcyclists.
• the helmet comprises an outer shell 1, a soft central part 2 with pockets 3 for suspension connectors 8, an inner shell 4, and the suspension connectors 8 connecting the inner shell 4 and the outer shell T
• a section through the helmet without the suspension connectors 8 can be seen, in Fig. 3, the helmet already has the suspension connectors 8.
• the central part 2 is inseparably connected to the outer rigid shell 1, whether using gluing, in-mold technique, or fasteners such as rivets. It is also not directly connected to the inner rigid shell 4. There is a free space between them, allowing movement between the shells 1, 4 of the helmet.
• the central part 2 is formed by injection molding EPS foam on the inner side of the outer shell 1 of the helmet with models of the suspension connectors placed at the locations where the real connectors 8 will be glued in later. The models are then removed, leaving pockets 3 in the central part 2 for the placement of the suspension connectors 8.
• a helmet consisting of only the outer shell 1 and the inner shell 4 without the soft central part 2 can be used, where the absorption of the impact forces, both rotational and linear, will be provided only by the tensegrity suspension connectors 8.
• a helmet can be used where the soft central part 2 will be inseparably connected to the inner shell 4 of the helmet, and the free space will be between the central part 2 and the outer shell T The width of the free space depends on the size of the suspension connector 8 and the length and elasticity of the suspensions 7.
• the material of the soft central part 2 is preferably expanded polystyrene, alternatively expanded polypropylene, expanded polyurethane, foam polymers, or mixtures of said polymers may be used, depending on the helmet manufacturing technology used.
• the thickness of the central part 2 is chosen according to the use of the helmet such that the ability to absorb the impact forces is sufficient, and the height of the suspension connector 8 depends on it.
• the material of the inner shell 1 and outer shell 4 may be polycarbonate, carbon fiber reinforced plastic, glass fiber reinforced plastic, Kevlar, molded plastics, acrylonitrile butadiene styrene, and others, depending on the helmet manufacturing technology used.
• the function of this rigid part is to protect the head mechanically during impact, and above all to prevent foreign bodies from penetrating the helmet.
• the inside of the helmet can be equipped with padding for a proper fit on the user’s head.
• At least three suspension connectors 8 are used. One near each ear area, one in the back of the occipital area.
• more connectors 8 spread over the helmet surface can be used (in the case of integral helmets also in the chin protection area), taking into account the fact that a larger number of connectors 8 reduces the volume of the central part 2, which absorbs the linear components of the impact.
• the connector 8 based on the principle of tensegrity comprises the following basic components - two rigid parts with brackets 6 and flexible suspensions 7, as can be seen in Fig. 4 and Fig. 5.
• the first and second rigid parts are connected by flexible suspensions 7.
• the rigid part comprises a base 5 of a lenticular or semilenticular shape and an integral bracket 6, which is connected at one end to the base 5 and the other end faces outwardly from the base and is terminated by the top of the bracket 6.
• the bracket 6 has a straight shape and extends from the base 5 towards the opposite base 5 at an angle of less than 90°, or may take different shapes, for example the letter L or J.
• the tops of the brackets 6 are preferably located in an axis passing through the center of the first and second bases 5 of the connector 8.
• the base 5 of the connector 8 can take different shapes. Preferably it is a shape having a round plan, a convex surface towards the outer shell 1 of the helmet and a concave surface towards the inner shell 4 of the helmet. Other shapes of the base 5 can be used, such as a triangle or another polygon, oval, etc., wherein the surfaces of the base 5 may be flat or slightly convex or concave.
• the connector 8 may also comprise several pairs of brackets 6, always opposite each other.
• the opposite brackets 6 are also connected to each other by the flexible suspensions 7 and the individual pairs of the brackets 6 are positioned axially symmetrically with respect to the base of the connector 8.
• Another alternative is brackets 6 connected by more than one flexible suspension 7.
• the flexible suspensions 7 may be made of wire (metallic, non-metallic, organic, synthetic), fiber (synthetic, glass, carbon, aramid), or micro-chain (metallic, synthetic).
• the rigid part of the connector 8 must be made of a rigid material (for example, 3D printed plastic HP PA12-Hewlet Packard Polyamide 12, HP PA 12 GB-Hewlet Packard Polyamide 12 Glass Beads).
• the attachment of the suspension 7 to the bases 5 allows the relative angle between the axis of the suspension and the normal vector of the base 5 to be changed. From a physical point of view, the suspension 7 can only work in a tensioned state. However, due to the specific shape, the whole connector 8 is structurally integral in shear (tangential stress) and in compression (normal stress). Further loss of energy can be ensured by gradual destruction of the part of the connector 8.
• the stiffness of the connector 8 can be adjusted by the stress of the suspension
• connection between the rigid parts and the suspension 7 can be made by drilling an opening in the rigid part, threading the suspension 7 through the opening and securing it with a knot and/or glue on the other side, or by securing it with a screw or plug or other stop.
• the connector 8 can be realized is to create rigid parts interleaved with each other by means of 3D printing.
• the rigid part has a base 5 which is subsequently glued into the inner shell 1 or outer shell 4 of the helmet.
• Three brackets 6 extend from the base 5 and connect in the space in front of the base 5.
• the first part of the connector 8 is of identical shape and is interleaved in the second part such that a tensegrity formation can be formed, i.e., the junction of the three brackets 6 of the bottom part is inserted in the space between the brackets 6 of the upper part.
• Manufacture using 3D printing eliminates the need to laboriously assemble the parts, as the parts can be printed directly interleaved.
• the base 5 and the element of the connected brackets 6 are manufactured separately and subsequently connected, e.g., by gluing, fusion, or fasteners.
• the parts are further connected by suspensions 7 at the place of the connection of the three brackets 6 and at the edge parts of the bases 5.
• Other variants of the tensegrity suspensions are also possible.
• the procedure for assembling the connection between the inner shell 4 and the outer shell 1 of the helmet comprises, first of all, the manufacture of the suspension connector 8.
• a first and a second part of the suspension connector 8 is manufactured, for example by 3D printing.
• Each part of the connector 8 comprises a base 5 and a bracket 6 extending therefrom.
• the first and second parts of the suspension connector 8 are connected by means of flexible suspensions 7, wherein the tension of the suspensions 7 is adjusted at the same time. This completes the suspension connector
• the first bases 5 of the suspension connectors 8 are rigidly connected to the inner shell 4 of the helmet.
• the connection is realized by a glue, fusion, or suitable fasteners.
• the outer shell 1 of the helmet is then placed and the second bases 5 of the suspension connectors 8 are rigidly connected to the outer shell 1 of the helmet, again by means of a glue, fusion, or other suitable fasteners.
• the glue can be applied either to the bases 5 of the connectors 8 or to the appropriate areas of the shell 1, 4 of the helmet.
• the steps of applying the central part 2 of the helmet are included in the manufacturing procedure before the step of connecting the first bases 5 of the suspension connectors 8 to the inner shell 4 of the helmet.
• Models of the suspension connectors 8 adapted to define the space for the suspension connectors 8 at the locations where the real connectors 8 will subsequently be located are placed on the inner shell 4 of the helmet, and e.g., EPS or other material of the central part 2 of the helmet is applied.
• the application is done by spraying or applying a fluid material, which is then cured or hardened with appropriate agents.
• the models have the same shape as the connector 8 with adequate clearance to allow the real connector 8 to move as desired.
• the size of the difference between the width of the model of the connector 8 and the width of the real connector 8 depends on the set stiffness of the suspension 7, the length of the suspension 7, and the stiffness of the individual parts of the connector 8. After application or curing of the central part 2 the models of the connectors 8 are removed and the procedure as described above continues.
• the central part 2 of the helmet is connected to the inner shell 4 of the helmet (alternatively the outer shell 1 of the helmet) by gluing, fusion, or fasteners before the step of connecting the first bases 5 of the suspension connectors 8 to the inner shell 4 of the helmet.
• the properties of the helmet in terms of its protective capabilities can be changed by adjusting the stiffness of the connector 8, or by using a suspension 7 with a different stiffness or with a non-linear characteristic in terms of the dependence of the force on the extension of the suspension 7.
• the change will result in a different stiffness/rotational stiffness of the connection between the inner shell 1 and the outer shell 4 of the helmet.
• a softer connector 8 is more preferable in applications where lighter impacts are expected.
• Helmet with multi-directional suspension is characterized by the ability to absorb rotational and linear forces at the same time. The absorption of rotational forces is particularly desirable in the case of motorcyclist injuries.
• the absorption properties of the suspension connector can be changed by the choice of the suspension, its elasticity, and length. This makes the principle also applicable in applications for helmets designed for other sports such as equestrianism, cycling, etc. Different sports are characterized by different injury mechanisms and therefore require different helmet parameters.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Helmets And Other Head Coverings (AREA)

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Citations (2)

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• 2021
  • 2021-11-01 CZ CZ2021-499A patent/CZ309734B6/cs unknown
• 2022
  • 2022-07-28 WO PCT/CZ2022/050066 patent/WO2023072321A1/en not_active Ceased
  • 2022-07-28 EP EP22757480.3A patent/EP4426154B1/en active Active

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