Helmet with flexible structure for improved force attenuation

A helmet includes a shell, a brim, ridges, and multiple flexible structures. The shell is shaped to receive a user's head. The brim covers the user's forehead and areas above the temples and ears and protrudes from the outer surface of the shell. The ridges are located along the back and top of the helmet and also protrude from the outer surface of the shell. The flexible structures, which are made of a material that is more flexible than the shell, the brim, and the ridges, are positioned in separation gaps between the shell and the brim and ridges. The shell, brim, ridges, and flexible structures are fused together as a single unibody. When the helmet is subjected to an impact on the brim or the ridges, the corresponding flexible structure deforms so that the brim or ridge moves relative to the shell. The deformation of the flexible structure attenuates the force of the impact, which improves the helmet's ability to protect the user from impacts.

BACKGROUND

This disclosure generally relates to protective headgear and more particularly to a helmet with a flexible structure incorporated into the outer layer.

Conventional helmets include two primary components—a rigid outer layer and a compressible inner layer—that perform two non-overlapping functions. The rigid outer layer is made of an inflexible material and covers a user's head. The compressible inner layer is made of a softer material, typically a type of padding or foam, and is positioned between the rigid outer layer and the user's head. When a helmet with this structure is subjected to an impact, the rigid outer layer disperses the force of the impact over a broader area. However, because the outer layer is made of an inflexible material, the outer layer does not flex or deform in any significant manner when subjected to an impact. As a result, the rigid outer layer transfers nearly the entire force of the impact to the compressible inner layer, and the compressible inner layer is the only component of the helmet that attenuates the force of the impact. A helmet's rigid outer layer typically has the minimum thickness needed to provide rigidity for the purpose of dispersing the anticipated impact forces of the activity for which the helmet is designed. The thickness of a helmet's compressible inner layer is typically limited by broader design goals like reducing the overall size and weight of the helmet, and this leads to limited attenuation of the impact force relative to what would cause a mild traumatic brain injury (e.g., a concussion).

This limitation is compounded by helmets for certain sports, such as hockey and lacrosse, which typically have a rigid outer layer with ridges and bumps that protrude outward from the user's head. These ridges and bumps act as I-beams that add additional rigidity to the outer layer, which can decrease the effectiveness of the portion of the compressible inner layer positioned directly below the ridges and bumps. Specifically, the ridges and bumps direct impact forces through these I-beams, bypassing the attenuation material in the cavity of these protrusions, which in turn further limits the attenuation of the impact force by the helmet.

SUMMARY

A helmet includes a shell, a brim, and a flexible structure fused together to act as a single body. The shell is shaped to receive a user's head. The brim protrudes from the outer surface of the shell and is typically located in a position corresponding to the user's forehead and optionally proceeding around each side near the temples and ears. The flexible structure is positioned in a separation gap between the brim and the shell and has a higher flexibility than the brim and the shell.

The shell, brim, and flexible structure may be formed of a first material, a second material, and a third material, respectively. The first material and the second material are relatively rigid materials, such as ABS (acrylonitrile butadiene styrene), PC (polycarbonate) or a co-polyester derivative, while the third material is a more flexible material, such as TPU (thermoplastic polyurethane), TPE (thermoplastic elastomer), soft PLA (polylactic acid), or rubber. The first material and the second material may be the same.

When the helmet is subjected to an impact on the brim, the flexible structure deforms so that the brim moves relative to the shell. Although the helmet may also include a compressible inner layer that compresses to help attenuate the force of the impact, the deformation of the flexible structure provides an additional mechanism for the helmet to attenuate the force of an impact by extending the time of a given impact and therefore lowering the overall rate of acceleration experienced by the player's head. In this design, any compressible material directly under the brim takes part in attenuating impacts, unlike a conventional helmet. At the same time, the brim typically does not move below the plane of the shell below it, which means it does not bottom out on the user's head. The fact that the compressible inner layer and the flexible structure can both operate to attenuate the force of an impact advantageously increases the helmet's overall ability to protect the user from head trauma associated with high-G impacts.

The figures depict various embodiments of the present invention for purposes of illustration only.

DETAILED DESCRIPTION

A helmet includes a shell, a brim, and a flexible structure. The shell is shaped to receive a user's head. The brim protrudes from the outer surface of the shell, covers the user's forehead, and extends to the sides of the head to the area corresponding to the user's temples and ears. The flexible structure, which is made of a material that is more flexible than the shell and the brim, joins the brim to the shell by filling a separation gap between the shell and the brim. The portion of the helmet that covers the rear of the user's head includes ridges that also protrude from the outer surface of the shell, and additional flexible structures join the ridges to the shell by filling a separation gap between the shell and the ridges. When the helmet is subjected to an impact on the brim or the ridges, the corresponding flexible structure deforms so that the brim or ridge moves relative to the shell. As described herein, deformation refers to any change in shape, either temporary or permanent, in a material or component resulting from physical pressure or stress. The deformation of the flexible structure attenuates the force of the impact, which improves the helmet's ability to protect the user from impacts.

FIGS. 1A-1Eillustrate various views of a helmet100, according to one embodiment of the invention. In the embodiment shown inFIGS. 1A-1E, the helmet100includes, among other elements, a shell105formed of a first material, a brim110formed of a second material, and a flexible structure115formed of a third material. The helmet further includes two ridges155A,155B along its top and rear. The structure and function of the ridges155A,155B are described in further detail with reference toFIGS. 4A-4B and 5A-5B. In addition to the components described herein, the helmet100can also include additional components not shown in the figures. For example, the helmet100may include a compressible inner layer (e.g., made of one or more pieces of foam, padding, or air vessels) positioned between the shell and the user's head that helps attenuate the force of impacts to the head. Other examples of additional components include a chin strap that keeps the helmet100secure on the user's head, a fit system that clamps around the head to secure it on the user's head, and a face covering, such as a visor, face shield, or cage, that protects part or all of the user's face.

As described herein, the first material (i.e., the material used for the shell) and the second material (i.e., the material used for the brim) are materials with a high rigidity and a high impact resistance. For example, the first and second materials may be acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or a co-polyester derivative. In some embodiments, the first and second materials are the same material. In other embodiments, the first and second materials are different materials to accommodate different impact scenarios and anticipated forces specific to the location of the helmet. For example, the first material is a type of ABS while the second material is a type of polycarbonate. As another example, the first material is one type of polycarbonate and the second material is a different type of polycarbonate.

As described herein, the third material (i.e., the material used for the flexible structure) is a material with a higher flexibility than the first and second materials. In addition, the third material may also have a relatively low stiffness (e.g., a Young's modulus below 50 MPa), a high elongation at break (e.g., greater than 100%), an ultimate tensile strength of at least 20 MPa, and a high fatigue limit (e.g., at least 10,000 cycles when tested at half the ultimate tensile strength of the third material). For example, the third material may be thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), soft polylactic acid (soft PLA), or rubber.

In other embodiments, the shell105may be formed of multiple materials that have the characteristics described with reference to the first material and the second material. For example, the shell105may comprise an inner core made of a type of ABS covered on all surfaces with a layer of a different type of ABS. This allows the surfaces of the shell105to be formed of a material with some additional favorable characteristic (e.g., higher scratch resistance, more easily pigmented) while the core of the shell105may be formed of a material with more favorable mechanical properties (e.g., higher rigidity, lighter weight). For similar reasons, the brim110may also be formed of multiple materials that have the characteristics described with reference to the first material and the second material, and the flexible structure115may be formed for multiple materials that have the characteristics described with reference to the third material.

FIGS. 1A, 1B, and 1Cillustrate a front perspective view, a right side view, and a front view, respectively, of the helmet100. Because these three figures illustrate various views of the same components (e.g., the shell105, the brim110, and the flexible structure115), certain aspects of these components will be described below with reference to all three of these figures.

The shell105is shaped to receive a user's head. For example, the shell105has a shape that substantially matches the curvature of a human head. Because head dimensions may vary between users, the shape of the shell105may vary between different embodiments of the helmet100so that different embodiments can accommodate different groups of users. For example, the size of the shell105may vary between different embodiments of the helmet100to accommodate users with larger or smaller heads. As another example, different embodiments of the helmet100may have a shell105with the same circumference but with a different width-to-length ratio in order to accommodate different head shapes.

The brim110is joined to the shell105by the flexible structure115. The brim110is sized and shaped so that there is a separation gap120A through120D (collectively referred to as the separation gap120) between the brim and the shell, and the flexible structure115is sized and shaped so that it occupies the separation gap120. In the illustrated embodiment, the shell105and the brim110are separate pieces of material. In this embodiment, the shell105has an elongated cutout at a position corresponding to the user's forehead and temples, and the brim110is sized to fit in the cutout so that the separation gap120surrounds the brim110along all four edges of the brim110. Specifically, the brim110in this embodiment has a left vertical edge (adjacent to the left separation gap120A), a right vertical edge (adjacent to the right separation gap120B), a top horizontal edge (adjacent to the top separation gap120C), and a bottom horizontal edge (adjacent to the bottom separation gap120D). The flexible structure115surrounds these four edges of the brim110and joins the edges of the brim110to the edges of the elongated cutout. Although the flexible structure115is illustrated in this embodiment as a single unitary piece, the flexible structure115may comprise multiple separate pieces. Likewise, the brim110and shell105may be joined directly to each other at one or more points along the separation gap120that would otherwise be occupied by the flexible structure115.

In another embodiment, the left and right ends of the brim110are joined directly to the shell105with no separation gap or flexible structure115in between (i.e., the left separation gap120A and the right separation gap120B are omitted, and the brim110is instead joined directly to the shell105at these two places). Instead, the flexible structure115occupies two discrete separation gaps120C,120D adjacent to the top and bottom edges of the brim110. In this embodiment, the brim110has a top horizontal edge (adjacent to the top separation gap120C) and a bottom horizontal edge (adjacent to the bottom separation gap120D) but does not have a left vertical edge or a right vertical edge.

FIG. 1Dillustrates a top view of the helmet100. In the illustrated embodiment, the brim110has a curved and elongated shape that is similar to the curvature of the side portions and the front portion of the shell. In this embodiment, the brim110is a single continuous strip of the second material and includes a left portion125A at a position covering the user's left temple, a right portion125B at a position covering the user's right temple, and a center portion125C at a position covering the user's forehead.

In other embodiments, the brim110may have a different structure. In one embodiment, the brim110comprises three separate pieces of the second material, with the first piece positioned to cover the user's left temple, the second piece positioned to cover the user's right temple, and the third piece positioned to cover the user's forehead. Each of these pieces may be curved in a manner similar to the curvature of the shell, or some or all of the pieces may be flat (which may simplify the manufacturing process by allowing for the use of off-the-shelf sheets of plastic). In this embodiment, the flexible structure115may fill separation gaps between the first, second, and third pieces of the brim110in addition to the separation gap between the brim110and the shell105.

In another embodiment, the brim110comprises a different number of separate pieces (e.g., two pieces, four pieces, five pieces). In still another embodiment, the brim110covers the user's forehead but does not extend to the sides of the helmet100to cover the user's temples. For example, the brim110includes the center portion125C shown inFIG. 1Dbut does not include the side portions125A,125B. In this embodiment, rectangular protrusions may be formed into the sides of the shell110to mimic the appearance of a brim that extends from the left temple to the right temple. In still another embodiment, the brim110extends farther toward to rear of the helmet100. For example, the brim110may extend so that the left and right portions125A,125B nearly make contact with the ridges155A,155B. In still another embodiment, the helmet100includes multiple brims110. For example, the helmet100may include a lower brim that covers the user's forehead and temples in a manner similar to the brim110in the illustrated embodiment in addition to an upper brim with a tighter curvature than the lower brim and positioned closer to the top of the user's head. An embodiment with the ridges arranged in this manner may be used, for example, as a lacrosse helmet.

FIG. 1Eis a side cutaway view of the helmet100taken along the vertical dashed line A-A′ shown inFIG. 1D. As noted above with reference toFIGS. 1A, 1B, and 1C, the shell105is shaped to receive a human head. As a result, the shell105has a concave inner surface135and a convex outer surface140, as illustrated inFIG. 1E. The brim110is joined to the shell105via the flexible structure115in a manner that causes the brim110to protrude from the outer surface140of the shell105. Because the brim110protrudes from the outer surface140, an impact object is more likely to make contact with the brim110rather than the shell105when hitting the sides or the front of the helmet100. Some of the advantages of having an impact make contact with the brim110are explained below with reference toFIG. 2.

In the illustrated embodiment, the shell105is formed of a solid piece of the first material. In other embodiments, the shell105may be formed of the first material but with a different internal structure. For example, the shell105may comprise two layers with pockets of air or a honeycomb structure sandwiched in between.

FIG. 2is a cross-sectional view of the front portion of the helmet100illustrating an example of a front impact205on the brim110of the helmet100. The front impact205can represent a broad area impact (e.g., a collision with another person's head, another person's body, or a fixed surface such as a floor, the ground, or a wall) or a small area impact (e.g., an impact by a projectile such as a puck or a collision with a fixed narrow object such as a pole or a beam). For example, the front impact205may occur if the user falls forward and his forehead hits the floor (i.e., a broad area impact). As another example, the front impact may occur if the user is playing as a goalie and is hit in the forehead with a hockey puck or lacrosse ball (i.e., a small area impact).

When the helmet100is subjected to the front impact205shown inFIG. 2, the impact205first makes contact with the front portion of the brim110. The impact205causes the brim110to move in translation210toward the user's head (i.e., towards left as shown inFIG. 2). The motion210, in turn, causes deformation in the flexible structure115. Specifically, the motion210causes the portion of the flexible structure115adjacent to the front portion of the brim to compress215. Although not shown in the cross sectional view ofFIG. 2, the motion210may also cause the flexible structure115adjacent to the side portions of the brim110to shear. The deformation of the flexible structure115allows the brim110to move in translation relative to the shell105and thus reduces motion of the shell105and impact to the shell105.

The deformation of the flexible structure115is advantageous, among other reasons, because it attenuates the force of the impact205. While the helmet100may further include a compressible inner lining that also attenuates impact forces, the deformation of the flexible structure115also attenuates the impact force, meaning that the helmet100has a greater overall ability to attenuate impact forces. This advantageously causes the helmet100to transfer a smaller portion of the impact force to the user's head and leads to increased protection for the user.

FIG. 3is a top view illustrating a side impact305on the brim110of the helmet100. For example, the impact305could represent a player being hit in the temple by a projectile, such as a hockey puck or lacrosse ball. A side impact like the impact305shown inFIG. 3is one of the most dangerous injuries in modern-day contact sports because it can cause the user's head to move in both translation (e.g., to the left as shown inFIG. 3) and in rotation (e.g., counterclockwise as shown inFIG. 3).

When the helmet100is subjected to the side impact305shown inFIG. 1, the projectile makes contact with the right portion (shown inFIG. 1Das right portion125B) of the brim110. The impact305causes the brim110to make a rotational movement310counterclockwise about the user's neck and also causes the brim110to make translational movement315to the left and to the back of the user's head. Similar to the impact205shown inFIG. 2, the motion310,315resulting from the impact305also causes deformation in flexible structure115. The deformation allows the brim110to move in rotation and translation relative to the shell105, which reduces the rotational and translational motion of the shell105. Again, the deformation of the flexible structure115is advantageous, among other reasons, because it attenuates the force of the impact305and causes the helmet100to transfer a smaller portion of the impact's rotational and translational forces to the user's head.

FIGS. 4A, 4B, and 4Cillustrate a rear perspective view, a top plan view, and a rear elevation view, respectively, of the helmet100, according to one embodiment. In addition to the shell105, the brim110, and the flexible structure115, the helmet100further includes two ridges155A,155B (collectively referred to as ridges155) and two additional flexible structures160A,160B (collectively referred to as flexible structures160). Because these three figures illustrate various views of the same components (e.g., the shell105, the ridges155, and the additional flexible structures160), certain aspects of these components will be described below with reference to all three of these figures.

In the illustrated embodiment, each ridge155A,155B has a curved, elongated shape that extends from a first end170A,170B at the top of the helmet100(corresponding to the top of the user's head) to a second end175A,175B near the bottom rear edge of the helmet100(corresponding to the occipital region of the user's head). Furthermore, the illustrated embodiment includes two separate ridges155A,155B positioned symmetrically, with the first ridge155A on the left side of the helmet100and the second ridge155B on the right side of the helmet100. In other embodiments, the helmet100may include a different number of ridges (e.g., three ridges, with a first ridge on the left, a second ridge on the right, and a third ridge in the middle), shorter ridges (e.g., the ridges may start and end on the back side of the helmet100without extending to the top of the helmet100), or ridges with a different orientation (e.g., horizontal ridges). In still other embodiments, the helmet may include longer ridges. For example, the ridges may traverse the entire length of the helmet from the bottom edge of the helmet, near the occipital region of the user's head, across the top (similar to the embodiment inFIG. 1D), and optionally continuing to the front where the flexible structure joins the shell to the brim.

The ridges155are joined to the shell105by the additional flexible structures160. Similar to the brim110, the ridges155are sized and shaped to provide separation gaps165A through165F (collectively referred to as separation gaps165) between the ridges155and the shell105, and the flexible structures160are placed between the separation gaps165. In the illustrated embodiment, each ridge155is directly joined to the shell105only at the first end170A,170B. Meanwhile, the separation gaps165surround each ridge on the other three sides. For example, the first ridge155A has a left vertical edge (adjacent to the left separation gap165A), a right vertical edge (adjacent to the right separation gap165B), and a bottom horizontal edge (adjacent to the bottom separation gap165C). Similarly, the second ridge155B has a left vertical edge (adjacent to the left separation gap165D), a right vertical edge (adjacent to the right separation gap165E), and a bottom horizontal edge (adjacent to the bottom separation gap165F). In another embodiment, each ridge155A,155B is also joined directly to the shell at the second end175A,175B (i.e., the bottom separation gaps165C,165F are omitted). In still another embodiment, the ridges155are not joined directly to the shell105at the first ends170A,170B; instead, there is a top separation gap (occupied by the additional flexible structures160A,160B) separating edges of the ridges155from the shell105.

In still another embodiment, the brim is omitted and the helmet includes one or more raised ridges that protrude at least several millimeters above the outer surface of the shell and extend lengthwise from the front of the helmet to the back of the helmet. An embodiment with the ridges arranged in this manner may be used, for example, as a cycling helmet.

In the illustrated embodiment, the ridges155are formed of the first material (i.e., the same material as the shell105) and are directly joined to the shell105at their respective first ends170A,170B. In other embodiments, the ridges155are formed of a fourth material which is different from the first material. In these embodiments, the fourth material may still have material properties similar to those of the first and second materials. For example, the fourth material may also have a high rigidity and a high impact resistance compared to the third material.

The ridges155are joined to the shell105in a manner that causes the ridges155to protrude from the outer surface in the rear portion of the shell105, which means broad area impacts to the back of the helmet100make contact with the ridges155instead of the shell105.

FIGS. 5A and 5Bare a side elevation view and a top plan view, respectively, of a rear impact505on the ridges155of the helmet100. For example, the impact505could represent a player falling backward onto the back of his head. When the helmet100is subject to the rear impact505shown inFIGS. 5A and 5B, an impact object is likely to make contact with the ridges155. The impact505causes the ridges155to move in translation510toward the user's head, and this motion510causes deformation in the additional flexible structures160. Similar to the brim110and the flexible structure115, the deformation in the additional flexible structures160allows the ridges155to move in translation relative to the shell105, which reduces the motion of the shell105and attenuates the force of the impact505to the shell105.

Although the foregoing description100describes a helmet100in which both the brim110and the ridges155are joined to the shell105(on at least some of their edges) with flexible structures115and160, other embodiments of the helmet may include some but not all of these features. For example, a helmet may include a brim joined to a shell with a flexible structure, but with conventional ridges that are formed into the shape of the shell (or with the ridges being omitted). As another example, a helmet may include ridges joined to the shell with flexible structures, but with a conventional brim that is formed into the shape of the shell (or with the brim being omitted).

In one embodiment, the helmet100is manufactured with an additive manufacturing process (e.g., 3D printing) that is capable of depositing different materials in each layer or multiple materials in a single layer. In other embodiments, the shell105(with the ridges155directly joined to the shell105) and the brim110are manufactured separately (e.g., via injection molding or 3D printing), and a plastic welding process is then used to join the brim110to the shell105by filling the separation gaps120and165with the third material to form the flexible structures115and160. In embodiments where the ridges155are not directly joined to the shell105(i.e., the ridges are surrounded by a separation gap on all four sides), the ridges155are also manufactured separately and then joined to the shell105via the plastic welding process.

In an alternative embodiment, the shell, brim, and flexible structure are all formed of the same material, but the material properties of the material and the dimensions (e.g., thickness) of each component are selected so that the flexible structure still has a higher flexibility than the other components. Thus, the brim in this embodiment can still move relative to the shell and attenuate impact forces. Additionally or alternatively, a helmet in this embodiment may further include ridges and additional flexible structures formed of the same material and with dimensions that are similarly selected to allow the ridges to move relative to the shell and attenuate impact forces. For example, the material may have an ultimate tensile strength similar to or greater than the ultimate tensile strength of ABS (e.g., between 30 and 100 MPa) and a greater elongation to break than ABS (e.g., the material may have an elongation to break between 10% and 400%). These material properties allow the flexible structure to be manufactured at a relatively low thickness. In this example, the flexible structure has a thickness of a few tenths of a millimeter (e.g., between 0.1 and 0.5 mm) while the shell and the brim have a significantly higher thickness (e.g., between 1.0 and 5.0 mm). The inherent lack of material resulting from the low thickness of the flexible structure results in a flexibility that is similar to the flexibility of a thicker flexible structure formed with a more flexible material (such the third material described above). This combination of material properties and dimensions allows the entire helmet to be manufactured from a single material while still retaining many of the desirable properties described herein, such as the ability for the flexible structure to attenuate impact forces.

Although the description in this disclosure is provided with reference to a helmet, in other embodiments the structural components described herein may be applied to other forms of protective headgear that cover a smaller portion of the user's head than a helmet. For example, a headband may include a flexible structure that allows a first portion of the headband to move relative to a second portion of the headband to help attenuate impact forces. As another example, a pair of eye goggles may include a flexible structure that allows each eye covering (or a portion of each eye covering) to move relative to one or more other portions of the goggles. In these embodiments, the protective headgear may include multiple distinct components fastened together (e.g., with buttons, clips, or straps).

All dimensions, materials, and specific numbers shown in the embodiments are given only by way of example, in order to aid the understanding of the invention; none of them are meant to limit the present invention, unless it is explicitly stated so.