Unit cell of a network structure

Abstract

One aspect of the invention relates to a unit cell (1) of a network structure (5), comprising three levels: • - a first level I, having a polygonal star shape with branches (2, 20, 21) of different heights, alternating or not, • - a second level II, connected to the first level I and forming a surface of revolution (3) terminated by an S-shaped rim (30) and, • - a third level III, connected to the second level II and comprising flexible strips (4) distributed uniformly over the periphery of the S-shaped rim (30).

Description

DESCRIPTION TITLE: UNIT CELL OF A NETWORK STRUCTURE TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of a network structure and more particularly the unit cells composing it as well as its use.

[0002] The present invention relates to a unit cell, the network structure and a body protection. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] There are a multitude of network structures for various applications, particularly to protect certain parts of the body. However, although deformable, these structures are often not flexible enough to allow sufficient freedom of movement to “forget” that one is wearing protection.

[0004] Indeed, it is necessary to protect the back of users during violent falls on hard ground while allowing freedom of rotational movement. For board sports such as skiing, snowboarding, rollerblading, skateboarding and even downhill biking, there are protections to ensure safety during acrobatic figures and to surpass oneself without fear for one's safety.

[0005] The existing solutions are presented in the form of superimposing layers of foam of different hardnesses or an absorbent structure in the form of an injected thermoplastic plate.

[0006] So, some protectors are made of rigid plastic, others are made of molded foam or reinforced textile. However, these protectors may not be flexible enough to follow the body's movements and therefore cannot provide optimal protection against injuries.

[0007] Rigid back protectors are therefore not flexible enough to follow the body's movements, which can lead to a lack of protection or even injuries.

[0008] There are also reinforced textile protectors, but they are not designed to adapt to body movements. Textile protectors can also be difficult to clean and maintain.

[0009] Molded foam guards may be more comfortable, but they are not strong enough to effectively protect against injury.

[0010] There is document FR2976775 disclosing a back protection device comprising a deformable support and a network structure extending over a surface of said support to provide back protection against impacts. However, it does not provide the necessary freedom of movement to “forget” that one is wearing protection, it is also non-breathable which makes it difficult to wear for a long period.

[0011] There is therefore a need for protection that is flexible, breathable and rigid enough to protect a user. SUMMARY OF THE INVENTION

[0012] The invention provides a solution to the problems mentioned above, by allowing the production of a network structure from a particular unit cell.

[0013] One aspect of the invention relates to a unit cell of a network structure, characterized in that it comprises three levels: a first level I of polygonal star shape with branches of different heights, alternating or not, a second level II connected to the first level I and forming a surface of revolution terminated by an S-shaped rim and, a third level III connected to the second level II and comprising flexible lamellae distributed uniformly on the periphery on an S-shaped rim.

[0014] Each level has its own specific features. The first level is used for force transmission, shock absorption, and helps ensure rigidity and prevent punctures. The second level offers high compressive strength, thanks in particular to the S-shaped edge, which is important for distributing the impact force over a larger area, helping to reduce the severity of impact damage. The third level provides shock absorption and greater comfort.

[0015] The branches of the star should preferably be of identical shape.

[0016] Advantageously, the surface of revolution is a cone of revolution or a cylinder of revolution. The cone of revolution, like the cylinder of revolution, are shapes that have good compressive strength and, as they are hollow, they remain light.

[0017] Advantageously, the cone of revolution has a flared part oriented towards the first level. In this case, the second level is formed by the stacking of two coaxial cones along the axis of revolution of said cones, the second cone being constituted by a part of the S of the S-shaped rim. The apex of the lower cone is connected to the lower cone by a surface which follows the shape of a Fermat spiral (S-shape), creating a tangential transition.

[0018] Advantageously, the flexible slats are curved outwards. The outward curvature of the slats allows for a larger shock-absorbing surface area.

[0019] Advantageously, the star-shaped polygonal shape includes an even number of branches, preferably six. The minimum even number of branches is four. This allows for better (most optimal) cooperation between the branches of cells in a network structure.

[0020] Advantageously, the star-shaped polygonal shape includes an odd number of branches. The minimum number of branches is then three.

[0021] Advantageously, the unit cell comprises the same number of flexible lamellae and branches of the star-shaped polygon. This facilitates the construction of a network structure.

[0022] A second aspect of the invention relates to a network structure comprising unit cells with at least one of the preceding characteristics. The alternating height branches of the first level of the star-shaped polygonal unit cell allows a high branch of one unit cell to be nested with a low branch of an adjacent unit cell. The high and low branches can thus adjust to absorb impacts and reduce pressure on certain parts of the network structure.

[0023] Advantageously, the lamellae of two adjacent unit cells are connected to each other forming a continuous link. The unit cells of the structure in network are thus connected to each other, allowing a continuous network structure to be created.

[0024] Advantageously, the network structure is produced using additive manufacturing. Additive manufacturing can be achieved with a thermoplastic material such as polyurethane (TPU), and the process can be, for example, HP's Multi Jet Fusion (MJF). TPU is a flexible and durable material that is often used in the production of 3D products, such as soft parts and coatings.

[0025] A third aspect of the invention is a body protector comprising the foregoing network structure.

[0026] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0027] The figures are presented as examples and in no way limit the invention.

[0028] [Fig. 1] is a section of a unit cell according to the invention,

[0029] [Fig. 2] is a perspective view from above of a first level of two nested unit cells,

[0030] [Fig. 3] is a section of a second level of a unit cell,

[0031] [Fig. 4] is a perspective view from above of a second level of a unit cell,

[0032] [Fig. 5] is a perspective view from above of a third level of a unit cell,

[0033] [Fig. 6] is a top perspective view of several unit cells forming a network structure,

[0034] [Fig. 7] is a side view of a folded network structure from the third level side,

[0035] [Fig. 8] is a side view of a folded network structure from the first level side. DETAILED DESCRIPTION

[0036] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0037] In the remainder of the description, we will call "top" or "upper" what corresponds to the top of figures 1 to 6, and "bottom" or "lower" what corresponds to the bottom of said figures.

[0038] The unit cell 1 illustrated in Figure 1 is broken down into three interconnected levels: a first level I of star-shaped polygonal shape with branches 2 of different heights, alternating or not, a second level II comprising a surface of revolution 3 ending in an S-shaped rim 30, and a third level III comprising flexible slats 4.

[0039] The first level I located in the upper part and in the shape of a star comprises high branches 20 and low branches 21 and the center of the star passing through an axis X has a central space 22. This difference in height makes it possible to fit a high branch 20 of a unit cell with a low branch 21 of another unit cell. The central space 22 allows air to circulate, to reduce the consumption of raw material and to facilitate sanding during manufacturing. Preferably the high branches 20 and low branches 21 are of identical shape. The branches are uniformly distributed, that is to say that in top view all the adjacent branches form an identical angle. The low branches 21 comprise a protrusion 210 in the lower part allowing the connection with the second level II The length of each side and the number of sides of each branch 2 are determined by the precise geometric specifications linked to the intended use.

[0040] The second level II comprises a surface of revolution 3 of axis X, a cone of revolution 31 in the illustrated example. This surface of revolution 3 is hollow which defines an intermediate cavity 33, and terminated in the upper part by a base ring 32 which is connected to the first level I. This base ring 32 is thicker than the rest of the surface of revolution 3, which allows a better connection with the protrusions 210 of the first level I. The surface of revolution 3 ends in part low by an S-shaped rim 30, the lower end 300 of the S is preferably directed towards the outside of the surface of revolution 3. The S-shape of the rim 30 acts as a shock absorber in the event of impacts, allowing the second level II to collapse and absorb the energy.

[0041] The third level III located in the lower part comprises several flexible strips 4, preferably of identical shape, and connected in the upper part to the rim 30 at the level of the lower end 300 of the S. The number of strips 4 can be identical to the number of branches 20 and 21 of the star shape. These strips 4 are preferably curved radially outwards.

[0042] The unit cell 1 makes it possible to create a network structure 5 visible in figure 6. This structure 5 connects several identical unit cells 1 on two levels in the following way: for the first level I: the high branches 20n of a first unit cell 1n overlap with a low branch 21n+1 of a neighboring unit cell 1n+1 (or 1n-1), for the third level III: the lamellae 4n of a first unit cell 1n is connected with a lamellae 4n+1 of a neighboring unit cell 1n+1.

[0043] Thus in the example illustrated, the unit cell 1 has six branches 2 comprising three high branches 20 and three low branches 21, and six lamellae 4. The six lamellae 4 are preferably placed below the six branches 2.

[0044] It can be seen in Figure 6 that each of the high branches 20n can overlap with a low branch 21n+1 of a neighboring unit cell 1n+1 and each lamella 4n can be connected with a lamella 4n+1 of a neighboring unit cell 1n+1. The network structure thus formed is continuous through the lamellae 4 and nested through the branches 2.

[0045] The alternation of the upper and lower parts allows for optimal distribution of the load applied to the network structure 5, which improves its mechanical resistance, like scales. The upper 20 and lower 21 branches can adjust to absorb impacts and reduce the pressure on certain parts of the structure. In addition, the geometric shape of the regular star-shaped polygon provides greater stability, which is particularly suitable for applications requiring impact protection because in this case, the upper 20 branches can lean on the adjacent lower branches 21 and thus reinforce the structure. In the event of an impact, the upper part consisting of all the upper branches 20 makes it possible to transmit the energy of the impact from the upper branch concerned to other neighboring upper branches via the lower branches 21, which can then absorb the energy and limit the bending by collision of the neighboring branches. The upper part also offers additional protection in the event of perforation by an object. Figure 8 shows the deformation of the network structure 5 when a force or an impact is applied to the upper part of the network structure 5, this deformation causes a hardening of the network structure. The branches overlap compactly without leaving a hollow space, which allows effective protection.

[0046] The S-shaped flange 30 connects the second level II and the third level III. This flange 30 acts as a shock absorber in the event of impacts, allowing the second level II to collapse and absorb energy. The second level II provides high compressive strength, which is important for distributing the impact force over a larger area, which helps reduce the severity of impact damage.

[0047] Additionally, the cone shape of the illustrated example maximizes rigidity while minimizing weight, which is important for applications such as body or back protection where additional weight can cause discomfort for the user. Using a cone shape also allows for a transition between different parts of the structure, which helps reduce local stress points and ensures even distribution of impact force across the entire lattice structure. Finally, the cone is an easy design to produce using 3D printing techniques, which can help reduce costs and production times.

[0048] The connection of adjacent slats 4 allows perfect cooperation between the different unit cells 1 without requiring subsequent assembly. These junctions between the unit cells 1 allow an extension of the network structure 5 during the user's movements due to the flexibility of the slats 4. The third level III will be able to transmit the force of the impact to other parts of the network structure 5, which improves comfort and better protects the user. The arrangement of the slats around the intermediate part allows also a better adaptation to the user's movements for increased comfort. We can see in Figure 7 that the deformation of the network structure 5 on the side of the third level III, in contact with the user, is very flexible giving flexibility to the network structure when a force is applied on this side.

[0049] The network structure 5 is preferably made by additive manufacturing with a thermoplastic polyurethane (TPU), or thermoplastic polyamide (TPA), polyethylene (PE), polypropylene (PP), polyvinyl (PVC), polystyrene (PS) material. TPU is a flexible and durable material that is often used in the production of 3D products, such as soft parts and coatings. The network structure is preferably monomaterial, which simplifies production processes, allowing for the rapid and efficient production of customized protections for users and these thermoplastics can be recycled.

[0050] Material selection can also determine mechanical properties such as compressive strength, flexibility, impact resistance, and durability. TPU is a flexible and durable material that is also water and impact resistant. This makes it particularly suitable for use in protective equipment.

[0051] An HP™ Multi Jet Fusion (MJF) printer, a 3D printer, or other additive manufacturing equipment can be used to create the lattice structure 5. This process uses a print head that sprays molten plastic powder onto a powder bed to build the object. The print head is guided by digital files that define the shapes, dimensions, and properties of the finished product. The molten powder solidifies to form a solid, uniform layer, and then a new layer of powder is spread over the bed to build the next layer of the object.

[0052] The process can be adjusted to adjust the mechanical and flexibility properties of the body armor. With MJF technology, it is possible to produce a network structure in a single piece without having to assemble the individual parts. This minimizes assembly errors and improves the quality of the final product. In addition, single-piece production optimizes material consumption and minimizes waste. Using MJF technology, it is possible to produce high-quality objects with optimal mechanical properties for use in industrial or sports applications.

[0053] The network structure 5 can be used for sports protective equipment such as body protection such as back protection, shin protection, knee protection, shoulder protection, elbow protection, etc. In this case, the first level I is placed on the outside and the third level III as close as possible to the user.

[0054] Depending on the maximum impact that the network structure will have to absorb, its thickness is calculated by simulation and defines the size of a cell. The length and thickness of each junction is sized so that it opposes elongation as little as possible and allows for movement. The network structure, thanks to its numerous voids, gives it great breathability and reduced weight.

Claims

CLAIMS

1. Unit cell (1) of a network structure (5), characterized in that it comprises three levels: - a first level I of polygonal star shape with branches (2, 20, 21) of different heights, alternating or not - a second level II connected to the first level I and forming a surface of revolution (3) ending in an S-shaped rim (30) and, - a third level III connected to the second level II and comprising flexible slats (4) distributed uniformly around the periphery of the S-shaped rim (30).

2. Unit cell (1) according to claim 1, characterized in that the surface of revolution (3) is a cone of revolution or a cylinder of revolution.

3. Unit cell (1) according to the preceding claim, characterized in that the cone of revolution has a flared part oriented towards the first level I.

4. Unit cell (1) according to one of the preceding claims, characterized in that the flexible slats (4) are curved outwards. [Claim s] Unit cell (1) according to one of the preceding claims, characterized in that the star-shaped polygonal shape comprises an even number of branches (2, 20, 21), preferably six.

6. Unit cell (1) according to one of claims 1 to 4, characterized in that the star-shaped polygonal shape comprises an odd number of branches (2, 20, 21).

7. Unit cell (1) according to one of the preceding claims, characterized in that it comprises the same number of flexible slats (4) and branches (2) of the star-shaped polygonal shape. [Claim s] Network structure (5) comprising unit cells (1) according to one of the preceding claims.

9. Network structure (5) according to the preceding claim characterized in that the slats (4) of two adjacent unit cells (1) are connected to each other forming a continuous link.

10. Network structure (5) according to claim 8 or 9, characterized in that it is produced by additive manufacturing.

11. Body protection comprising a network structure (5) according to one of claims 8 to 10.

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