Patent Description:
Action sports (e.g., skateboarding, snowboarding, bicycle motocross (BMX), downhill mountain biking, and the like), motorsports (e.g., off-road and on-road car and motorcycle riding and racing) and traditional contact sports (e.g., football and hockey) continue to grow at a significant pace throughout the world as each of these sports expands into wider participant demographics. While technology and sophisticated training regimes continue to improve the performance capabilities for such athletes/participants, the risk of injury attendant to these activities also increases. Current "state of the art" helmets are not keeping pace with the evolution of sports and the capabilities of athletes. At the same time, science is providing alarming data related to the traumatic effects of both repetitive but moderate, and severe impacts to the head. While concussions are at the forefront of current concerns, rotational brain injuries from the same concussive impacts are no less of a concern, and in fact, are potentially more troublesome. <CIT> discloses a helmet comprising an outer liner and an inner liner slidably coupled to an interior surface of the outer liner. The outer liner comprises an interior surface and the inner liner comprises an exterior surface. The inner liner is composed of an elastically deformable material. A majority of the interior surface of the outer liner and a majority of the exterior surface of the inner liner are both substantially parallel to a pseudo-spherical surface having a coronal cross section that is circular with a first radius and a sagittal cross section that is circular with a second radius different from the first radius. The inner liner is elastically deformable along the interior surface of the outer liner in response to rotation of the outer liner relative to the inner liner caused by an impact to the helmet.

According to the present invention, there is provided a helmet according to claim <NUM>. Embodiments provide omnidirectional impact energy management systems that can significantly reduce both rotational and linear forces generated from impacts to a helmet over a broad spectrum of energy levels.

Embodiments, enable the production of hard-shelled safety helmets that can provide a controlled internal omnidirectional relative displacement capability, including relative rotation and translation, between the internal components thereof. The systems enhance modern helmet designs for the improved safety and well-being of athletes and recreational participants in sporting activities in the event of any type of impact to the wearer's head. These designs specifically address, among other things, the management, control, and reduction of angular acceleration forces, while simultaneously reducing linear impact forces acting on the wearer's head during such impacts.

A more complete understanding of embodiments of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly, and within which like reference numerals are used to identify like elements illustrated in one or more of the figures thereof.

Omnidirectonal impact energy management systems for helmets are provided that can significantly reduce both rotational and linear forces generated from impacts imparted to the helmets. The systems enable a controlled internal omnidirectional relative displacement capability, including relative rotational and translational movement, between the internal components of a hard shelled safety helmet.

One or more embodiments disclosed herein are particularly well suited to helmets that can provide improved protection from both potentially catastrophic impacts and repetitive impacts of varying force that, while not causing acute brain injury, can cause cumulative harm. The problem of cumulative brain injury, i.e., Second Impact Syndrome (SIS), is increasingly recognized as a serious problem in certain sports, such as American football, where much of the force of non-catastrophic contact is transferred to the head of the wearer. In various example embodiments, helmets are configured with dampers of specific flex and compression characteristics to manage a wide range of repetitive and severe impacts from all directions, thus addressing the multitude of different risks associated with diverse sports, such as football, baseball, bicycle riding, motorcycle riding, skateboarding, rock climbing, hockey, snowboarding, snow skiing, auto racing, and the like.

Head injuries result from two types of mechanical forces - contact and non-contact. Contact injuries arise when the head strikes or is struck by another object. Non-contact injuries are occasioned by cranial accelerations or decelerations caused by forces acting on the head other than through contact with another object, such as whiplash-induced forces. Two types of cranial acceleration are recognized, which can act separately or in combination with each other. "Translational" acceleration occurs when the brain's center of gravity (CG), located approximately at the pineal gland, moves in a generally straight line. "Rotational" or angular acceleration occurs when the head turns about its CG with or without linear movement of the CG.

Translational accelerations/decelerations can result in so-called "coup" and "contrecoup'" head injuries that respectively occur directly under the site of impact with an object and on the side of the head opposite the area that was impacted. By contrast, studies of the biomechanics of brain injury have established that forces applied to the head which result in a rotation of the brain about its CG cause diffuse brain injuries. It is this type of movement that is responsible for subdural hematomas and diffuse axonal injury (DAI), one of the most devastating types of traumatic brain injury.

Referring to <FIG>, the risk of rotational brain injury is greatest when an impact force <NUM> is applied to the head or helmet <NUM> of a wearer from at an oblique angle, i.e., greater or less than <NUM> degrees to a perpendicular plane <NUM> drawn through the CG <NUM> of the brain. Such impacts cause rotational acceleration <NUM> of the brain around CG, potentially shearing brain tissue and causing DAI. However, given the distribution of brain matter, even direct linear or translational impacts can generate shear forces within the brain sufficient to cause rotational brain injuries. Angular acceleration forces can become greater, depending on the severity (i.e., force) of the impact, the degree of separation of the impact force <NUM> from <NUM> degrees to the perpendicular plane <NUM>, and the type of protective device, if any, that the affected individual is wearing. Rotational brain injuries can be serious, long lasting, and potentially life threatening.

Safety helmets generally use relatively hard exterior shells and relatively soft, flexible, compressible interior padding, e.g., fit padding, foam padding, air filled bladders, or other structures, to manage impact forces. When the force applied to the helmet exceeds the capability of the combined resources of the helmet to reduce impacts, energy is transferred to the head and brain of the user at an accelerated rate. This can result in moderate concussion or severe brain injury, including a rotational brain injury, depending on the magnitude of the impact energy.

Safety helmets are designed to absorb and dissipate as much energy as possible over the greatest amount of time possible. Whether the impact causes direct linear or translational acceleration/deceleration forces or angular acceleration/deceleration forces, the helmet should eliminate or substantially reduce the amount of energy transmitted to the user's head and brain.

<FIG> is a prospective view of an example helmet, in accordance with an embodiment. <FIG> shows a helmet <NUM> that includes outer shell <NUM>, first liner <NUM>, polymer liner <NUM>, second liner <NUM>, carrier <NUM>, dampers <NUM>, and side liner <NUM>.

Outer shell <NUM> can be a relatively hard shell that forms an outer structure that contains other components of helmet <NUM>. The relatively hard outer shell <NUM> can be manufactured from conventional materials, such as fiber-resin lay-up type materials, polycarbonate plastics, polyurethane, or any other appropriate materials, in various thicknesses of material, depending on the specific application intended for the helmet <NUM>.

First liner <NUM> is coupled or connected (e.g., coupled via fasteners and/or adhesives or directly connected through in-molding or co-molding) to outer shell <NUM>. Outer shell <NUM> is disposed at least partially circumferentially around first liner <NUM>. An outer side of first liner <NUM> can be configured to be disposed within an inner side of outer shell <NUM>. A shape of the outer side of first liner <NUM> can substantially match a shape of an inner side of outer shell <NUM>. In certain embodiments, the inner side of outer shell <NUM> and/or the outer side of first liner <NUM> can include one or more features to prevent first liner <NUM> from moving excessively relative to outer shell <NUM>. The "inner side" can be the side of the component closer to the head of the wearer when helmet <NUM> is worn. By contrast, the "outer side" is the side of the component farther away from the head of the wearer when helmet <NUM> is worn.

First liner <NUM>, second liner <NUM>, and/or other liners can include various features configured for user comfort, to tune impact absorption, or both. For example, first liner <NUM> includes opening <NUM>. Opening <NUM> can be configured to allow airflow to flow through first liner <NUM> to cool a wearer's head. Also, opening <NUM> can be configured to allow for first liner <NUM> to deflect more in certain directions, tuning the impact absorption property of first liner <NUM>.

Second liner <NUM> can be configured to be disposed in contact with a wearer's head, either directly or via a fitment of a so-called "comfort liner. " Second liner <NUM> can also be a hollow, semispheroidal, liner. First liner <NUM>, second liner <NUM>, and/or other liners can be formed of any suitable material, including energy absorbing materials such as expanded polystyrene (EPS) or expanded polypropylene (EPP). Such material can be configured to deform when subjected to a force (e.g., from an external impact). The deformation can absorb the force and protect a wearer's head. In certain embodiments, the force can be absorbed through a combination of one or more liners and/or other features additional to first liner <NUM> and second liner <NUM>.

Second liner <NUM> is configured to be disposed circumferentially within first liner <NUM>. In such configurations, an outer side of second liner <NUM> can be configured to be disposed within an inner side of first liner <NUM>. A shape of the outer side of second liner <NUM> can substantially match a shape of an inner side of first liner <NUM>.

In certain embodiments, the inner side of first liner <NUM> and/or the outer side of second liner <NUM> can include one or more features to prevent second liner <NUM> from moving excessively relative to first liner <NUM>. However, certain embodiments can allow for second liner <NUM> to move relative to first liner <NUM> (e.g., can allow for rotation of second liner <NUM> relative to first liner <NUM>). Such movement may be configured to be constrained such that relative movement is prevented if the relative movement is greater than a threshold amount. Such relative movement can prevent injury to the wearer (e.g., during oblique impacts).

One or more additional components are disposed between second liner <NUM> and first liner <NUM>. Such components can be configured to tune the allowable movement of second liner <NUM> relative to first liner <NUM>. Polymer liner <NUM> is one such component. Polymer liner <NUM> is coupled to second liner <NUM>, first liner <NUM>, and/or another portion of helmet <NUM> via, for example, mechanical fasteners such as bolts, nuts, standoffs, pins, snaps, rivets <NUM>, or other such fasteners, adhesives, friction fits, and/or another such technique. In certain other embodiments, polymer liner <NUM> can be co-molded onto second liner <NUM>.

Polymer liner <NUM> creates a low friction interface between mating part surfaces (e.g., between first liner <NUM> and second liner <NUM> or between other components such as between first liner <NUM> or second liner <NUM> and an intermediate liner). The low friction interface can allow and/or enhance rotational shearing movement between the components as, for example, polymer liner <NUM> can form a surface for first liner <NUM> and/or second liner <NUM> to slide, rotate, and/or move relative to one another on. Furthermore, polymer liner <NUM> can be coupled to or co-molded onto a surface of second liner <NUM> (e.g., an outer surface of second liner <NUM>). Polymer liner <NUM> can enhance the strength of the component in compression loading, hoop tensile strength, and/or another structural aspect. Accordingly, polymer liner <NUM> can be constructed from a material with a higher modulus of elasticity. Also, polymer liner <NUM> can form a surface or base for other components to couple to (e.g., dampers, liners, rivets, and/or other such components).

Pads <NUM> can be tuned to control relative movement between first liner <NUM>, second liner <NUM>, polymer liner <NUM>, and/or other components of helmet <NUM>. As shown in <FIG>, pads <NUM> are coupled to first liner <NUM>. First liner <NUM> includes protrusions <NUM> and one or more pads <NUM> are disposed on such protrusions. Disposing pads <NUM> on protrusions <NUM> allows for an air gap <NUM> to be disposed between first liner <NUM> and polymer liner <NUM> and/or second liner <NUM>. Further, disposing pads <NUM> on protrusions <NUM> allow for tuning of the force required to move polymer liner <NUM> and/or second liner <NUM> relative to first liner <NUM>. Other aspects to tune such force include the coefficient of friction of pads <NUM>, the area of pads <NUM> that contact polymer liner <NUM> and/or second liner <NUM>, and/or the amount of pads <NUM>.

Air gap <NUM> can be disposed between liners of helmet <NUM>, such as first liner <NUM> and second liner <NUM>, to allow motion between the liners. In certain embodiments, air gap <NUM> can be partially or fully filled by compressible material <NUM>. Compressible material <NUM> can be rubber dampers, damping towers, and/or compressible gels or foams in various geometric shapes. Such features can control displacement between the liners.

Thus, compressible material <NUM> can be coupled to first liner <NUM>, second liner <NUM>, and/or other liners to partially fill the gap between the liners. Compressible material <NUM> can be coupled to first liner <NUM>, second liner <NUM>, and/or other liners via mechanical fasteners, adhesives, and/or elastomeric bands <NUM>. Elastomeric bands <NUM> can be attached to components (e.g., compressible material <NUM>, first liner <NUM>, second liner <NUM>, another such liner, and/or other components of helmet <NUM>) to couple two or more components together, but allow each component to displace linearly and/or shear rotationally relative to each other upon an impact. Elastomeric bands <NUM> can then pull the components back towards each other to position the components in the original positions after the impact event is over.

Protrusions <NUM> can be raised features such as towers, cylinders, cones, domes, ribs, standoffs, and/or other features. Protrusions <NUM> are configured to create separation between two or more liners (first liner <NUM> and second liner <NUM>). Such separation can create a gap that allows for linear and rotational displacement between the two liners. There are a plurality of protrusions <NUM>. The plurality of protrusions <NUM> includes protrusions of varying heights. The differences in height allows for different amounts of protrusions <NUM> to engage and, thus, prevent deformation at different compression levels of the liners. Thus, protrusions <NUM> can be tuned so that only some of protrusions <NUM> (and/or pads <NUM>) contact polymer liner <NUM>, second liner <NUM>, and/or other liners of helmet <NUM> when unloaded (e.g., when helmet <NUM> is not experiencing an impact). The position of components of helmet <NUM> when not experiencing an impact can be called the unloaded position. When impact forces are experienced by helmet <NUM>, larger forces result in progressively larger amounts of protrusions coming into contact with a corresponding liner. Having a larger amount of protrusions <NUM> increases resistance to deflection and, thus, prevents the liners from "bottoming out" and increases protection to the wearer.

According to the claimed invention protrusions <NUM> are disposed on first liner <NUM>, other non-claimed embodiments can dispose protrusions on other liners. Protrusions can be disposed on sides of one or both adjacent liners to separate the two liners and allow for creation of a gap for omnidirectional movement.

While pads <NUM> in certain embodiments can be a separate part from the liner, according to the claimed invention pads <NUM> are a portion of protrusion <NUM> that is the same material as protrusion <NUM> and/or a different material from protrusion <NUM> (e.g., a separate material that is co-molded or in-molded and/or connected via snaps, interlocking geometry features on each part, and/or bonding with adhesives). Pads <NUM>, in non-claimed embodiments, can also be coupled to a liner different or additional to the liner of pad <NUM> and/or coupled to carrier <NUM> via snaps, interlocking geometry features on each part, bonding with adhesives or in-molded or co-molded. One or more of pads <NUM> can be made from a low friction material and/or a rigid material. Pads <NUM> made from rigid materials can aid in distribution of forces from impact and thus provide further wearer protection.

Pads <NUM> can contact polymer liner <NUM>, second liner <NUM>, carrier <NUM>, and/or another portion of helmet <NUM>. In certain embodiments, pads <NUM> can be different coefficients of friction when contacting different surfaces. Thus, if pad <NUM> contacts polymer liner <NUM>, the coefficient of friction can be a first coefficient of friction. If pad <NUM> contacts second liner <NUM>, the coefficient of friction can be a second coefficient of friction and if pad <NUM> contacts carrier <NUM>, the coefficient of friction can be a third coefficient of friction. In various non-claimed embodiments, certain pads are disposed on polymer liner <NUM>, other pads can be disposed on second liner <NUM>, and further pads can be disposed on carrier <NUM>.

Pads <NUM> can be positioned so that, in certain directions of rotation, one or more of pads <NUM> can contact another component, changing the coefficient of friction and thus the force absorption property. For example, one or more of pads <NUM> can, in an unloaded position, be disposed on polymer liner <NUM>. The interface of pad <NUM> to polymer liner <NUM> is a first coefficient of friction. Rotation of polymer liner <NUM> relative to first liner <NUM> can then cause pad <NUM> to contact carrier <NUM>. The interface of pad <NUM> to carrier <NUM> can be a second coefficient of friction and pad <NUM> riding over ridges of carrier <NUM> can provide additional resistance to movement. Thus, pads <NUM> can be configured to provide different amounts of rotational resistance (e.g., resistance of rotation of first liner <NUM> relative to polymer liner <NUM>, second liner <NUM>, and/or carrier <NUM>) depending on the amount of rotation, and thus the positioning, of first liner <NUM> relative to polymer liner <NUM>, second liner <NUM>, and/or carrier <NUM>. As such, positioning of pad <NUM> can tune rotational resistance of various liners to be progressive, digressive, or both at certain points of travel. Pad <NUM> can also be configured to be a connected body between two or more protrusions <NUM> and/or be a bridging surface supported by protrusion <NUM> and attached to protrusion <NUM> or first liner <NUM> with fasteners, pins, and/or adhesives, and/or bonded or co-molded into first liner <NUM> and/or second liner <NUM>. However, according to the claimed invention a pad is coupled to the first end of a first protrusion.

Carrier <NUM> can form a web like structure and/or be formed in another shape. Carrier <NUM> can be coupled to one or more liners and strengthen the one or more liners. Thus, carrier <NUM> can, for example, provide additional hoop strength to one or more liners (e.g., first liner <NUM> and/or second liner <NUM>) and/or can prevent uncontrolled deflection of the liners and thus, for example, ensure that second liner <NUM> always maintains a certain general shape. The shape of carrier <NUM> can be similar to that of the inner and/or outer surface of first liner <NUM>, second liner <NUM>, polymer liner <NUM>, and/or another such component.

Carrier <NUM> can be co-molded into second liner <NUM> so that the web like arms forming the web like structure are below the outside surface of second liner <NUM>. In such a configuration, only specific areas of carrier <NUM> are disposed on or above an outer surface of second liner <NUM>. Such specific areas can be configured to be attachment points for other components such as dampers or towers and/or to provide low friction points for contact with other components. Such a configuration allows for the carrier <NUM> to provide increased hoop strength to second liner <NUM>, in addition to being configured to provide mounting and/or interface points for other components as described herein, while not or minimally creating additional surface features on the outside surface of second liner <NUM>.

Carrier <NUM> can be disposed between a plurality of components (e.g., between second liner <NUM>, first liner <NUM>, and/or polymer liner <NUM>) and coupled to one or more such components to provide a support structure for the components and/or to aid in aligning and positioning such components. For example, carrier <NUM> can be coupled to one or more of the components (e.g., coupled to second liner <NUM>, first liner <NUM>, polymer liner <NUM>, and/or another component) through, for example, mechanical fasteners such as bolts, nuts, pins, snaps, standoffs, rivets <NUM>, or other such fasteners, adhesives, friction fits, and/or another such technique.

Also, carrier <NUM> can align and/or position additional components such as compressible members, such as damping towers, elastomeric dampers, compressible foams, compressible gels or any component that controls displacement between two or more components (e.g., liners) in compression and/or shear. Such additional components can be coupled and/or attached to carrier <NUM> via techniques described herein (e.g., via the mechanical, adhesive, and/or friction fit techniques and/or co-molded into carrier <NUM>) and can allow for omnidirectional displacement of components relative to one another.

An example of such a component is damper <NUM>. Helmet <NUM> can include one or more dampers <NUM> coupled to various components. For example, dampers <NUM> can include a first end and a second end. Dampers <NUM> of helmet <NUM> can be coupled to carrier <NUM> at the first end and first liner <NUM> at the second end.

Dampers <NUM> can include the first end, and the second end, and a damper body disposed between the first end and the second end. The damper body can allow relative movement between the first end and the second end. For example, damper body can be flexible and allow the first end to translate and/or rotate relative to the second end. In certain embodiments, dampers <NUM> or a portion thereof can be elastomeric.

The first end and/or the second end of dampers <NUM> can include concave and/or convex features to couple to the respective liner and/or carrier. Such features can be complementary in shape to features of the respective liner and/or carrier. Dampers <NUM> can include elongated cylindrical members having opposite ends respectively retained within inserts attached to the respective liner and/or carrier. Such inserts can include a variety of different materials and configurations and can be attached to the corresponding liner and/or carrier via a variety of attachment techniques.

Dampers <NUM> can be provided at selected points around the circumfery of helmet <NUM>. Dampers <NUM> of different designs can be provided for specific applications and effectively "tuned" to manage the anticipated rotational and translational forces applied thereto. Dampers <NUM> can be configured in a wide range of configurations and materials varying from those shown and described in the example embodiments, and the general principles described herein can be applied without departing from the scope of the invention.

Dampers <NUM>, first liner <NUM>, second liner <NUM>, polymer liner <NUM>, carrier <NUM>, pads <NUM>, and/or other features can be variously configured to control the amount of rotational force that will cause displacement of the various liners of the helmet <NUM> and can be configured such that they will tend to cause the second liner <NUM> to return to its original position relative to the first liner <NUM> after the force of an impact is removed from the helmet <NUM>.

Side liner <NUM> can be a further liner of helmet <NUM>. Side liner <NUM> can, for example, be configured to be disposed next to a jaw of the wearer when helmet <NUM> is worn. Side liner <NUM> can further be coupled to move relative to first liner <NUM>, second liner <NUM>, and/or another such liner in the event of an impact on helmet <NUM>. Side liner <NUM> can be secured around the jaws of the wearer to secure orientation of helmet <NUM> to the face of the wearer. In certain non-claimed embodiments, side liner <NUM> can be a portion or a segment of outer liner <NUM>, inner liner <NUM>, or another liner. Such a configuration is further described herein.

In certain embodiments, rearward portions of helmet <NUM> may include a rear cutout <NUM>. Rear cutout <NUM> can be in alignment with the cervical area of the spine of the wearer. Rear cutout <NUM> can be a central cutout configured to allow for more clearance vertically from the bottom of helmet <NUM> in relation to the adjacent helmet material to the left and right of rear cutout <NUM>. Rear cutout <NUM> allows for deflection of first liner <NUM>, second liner <NUM>, and/or other liners in an outward direction. Such deflection can be caused by, for example, rotational slip of helmet <NUM> in the aft direction (e.g., slip towards the rear of helmet <NUM>). Rear cutout <NUM> allowing for deflection of first liner <NUM>, second liner <NUM>, and/or other liners can better protect the cervical spine area of the wearer by relieving pressure from the area by allowing for displacement of first liner <NUM>, second liner <NUM>, and/or other liners away from the area and, thus, preventing such displacement from exerting force on the cervical spine area.

<FIG> is a partial side cross-sectional view of the example helmet, in accordance with an embodiment. Helmet <NUM> of <FIG> can be similar to helmet <NUM> of <FIG>. However, <FIG> shows helmet <NUM> with third liner <NUM>. Third liner <NUM> can be similar to liners described herein and can be configured to be disposed between a wearer's head and second liner <NUM> and be disposed in contact with the wearer's head, either directly or via a "comfort liner. " Third liner <NUM> can be a hollow, semispheroidal liner formed from any suitable material, including energy absorbing materials such as expanded polystyrene (EPS) or expanded polypropylene (EPP) to deform when subjected to a force (e.g., from an external impact).

In various embodiments, the ratio of thickness between such a second liner <NUM> and third liner <NUM> may vary significantly. For example, in certain embodiments, second liner <NUM> may be made from a harder plastic material such as ABS, PC, PA6, or other suitable materials. Such an embodiment of second liner <NUM> may be only <NUM> to <NUM> millimeters thick. In such an embodiment, polymer liner <NUM> and second liner <NUM> may thus be incorporated into the same liner. Such an embodiment may include a third liner <NUM> that is much thicker than second liner <NUM>. The thin second liner <NUM> may thus allow for third liner <NUM> to occupy more of the available volume space and. Such a configuration would allow for second liner <NUM> to move omnidirectionally in relation to first liner <NUM> while third liner130 is configured of thick energy absorbing foam (significantly thicker than second liner <NUM>, such as between <NUM> to <NUM> millimeters thick) that will contact the wearer's head either directly or via a comfort liner, increasing user comfort. In other embodiments, second liner <NUM> may be similar in thickness to third liner <NUM> or second liner <NUM> may be thicker than third liner <NUM>.

Third liner <NUM> can be disposed within second liner <NUM> and can be configured to move (e.g., translate and/or rotate) relative to second liner <NUM>. Air gap <NUM> can be disposed between third liner <NUM> and second liner <NUM> to allow for displacement of second liner <NUM> relative to third liner <NUM> and/or vice versa. Air gap <NUM>, similar to air gap <NUM>, is a space for second liner <NUM> and/or third liner <NUM> to compress and/or displace into and, thus, allows for omnidirectional displacement in linear and shear of second liner <NUM> and/or third liner <NUM>. Furthermore, in certain embodiments, first liner <NUM>, second liner <NUM>, and/or third liner <NUM> can be formed from the same or different materials with different stiffness. In certain such embodiments, second liner <NUM> can be softer than first liner <NUM> and/or third liner <NUM> and can, thus, effectively function as a gap that allows for third liner <NUM> to move (e.g., translate and/or rotate) relative to first liner <NUM>.

In certain embodiments, second liner <NUM> can be configured to be disposed circumferentially within first liner <NUM>. In such configurations, an outer side of second liner <NUM> can be configured to be disposed within an inner side of first liner <NUM>. A shape of the outer side of second liner <NUM> can substantially match a shape of an inner side of first liner <NUM>.

<FIG> is a partial side cross-sectional view of certain components of the example helmet, in accordance with an embodiment. Helmet <NUM> of <FIG> illustrates carrier <NUM>. Dampers <NUM> are coupled to carrier <NUM> and first liner <NUM>. As shown in <FIG>, a first end of dampers <NUM> can be disposed within an opening of first liner <NUM>. Disposing the first end within the opening can allow for first liner <NUM> to securely hold damper <NUM>. A second end of damper <NUM> can be coupled to carrier <NUM>. In certain embodiments, the second end of damper <NUM> can be molded to carrier <NUM> or can be separate from carrier <NUM> and coupled to carrier <NUM>. Damper <NUM> can allow for and control movement of first liner <NUM> relative to carrier <NUM>.

Furthermore, as shown in <FIG>, pads <NUM> can be inserted into protrusions <NUM> and held within protrusions through a barb on an end of pads <NUM>. At least some of pads <NUM> can be configured to contact carrier <NUM> when in an unloaded position. Certain displacement of first liner <NUM> relative to carrier <NUM> can then move certain pads <NUM> so that they no longer contact carrier <NUM>.

<FIG> is a bottom view of certain components of the example helmet, in accordance with an embodiment. <FIG> shows helmet <NUM> with pads <NUM> and carrier <NUM>. As shown in <FIG>, certain pads <NUM> do not contact carrier <NUM> in an unloaded position. In certain such embodiments, pads <NUM> will only contact carrier <NUM> or another portion of helmet <NUM> (not shown) if helmet <NUM> experiences a force greater than a threshold force that leads to deflection of certain components greater than a threshold deflection amount.

<FIG> is a side cross-sectional view of certain components of the example helmet, in accordance with a non-claimed embodiment. Helmet <NUM> shows first liner <NUM>, second liner <NUM>, and third liner <NUM>. Air gap <NUM> is disposed between first liner <NUM> and second liner <NUM>. Air gap <NUM> is disposed between second liner <NUM> and third liner <NUM>. While in the unloaded position, portions of first liner <NUM> can contact second liner <NUM> and portions of second liner <NUM> can contact third liner <NUM>, but air gaps <NUM> and <NUM> allow for deflection of liners relative to each other when experiencing a load on helmet <NUM>. In certain embodiments, air gaps <NUM> and/or <NUM> can be fully or partially filled with compressible materials such as rubber dampers, damping towers, and/or compressible gels or foams in various geometric shapes.

<FIG> is a bottom view of certain components of the example helmet, in accordance with an embodiment. As shown in <FIG>, first liner <NUM> of helmet <NUM> includes a plurality of sections. Such sections can be defined by grooves or cuts within first liner <NUM>. Dividing first liner <NUM> into sections allows for first liner <NUM> to further accommodate omnidirectional movement. The various sections of first liner <NUM> can move relative to each other for at least a first distance and thus can move independently or semi-independently of other sections. In other embodiments, other liners (e.g., second liner <NUM> and/or third liner <NUM>) can, additionally or alternatively, be multi-section liners.

Protrusions <NUM> and pads <NUM> are disposed on various sections of the liners. As shown in <FIG>, certain pads <NUM> are coupled to certain protrusions, but other protrusions are not coupled to pads <NUM>. As the coefficient of friction of bare protrusions and pads is different, disposing pads on certain protrusions, but not all protrusions, is used to tune the impact absorption and resistance to movement of the liners. However, according to the claimed invention, a pad is coupled to the first end of a first protrusion, but not a second protrusion.

<FIG> is a flowchart detailing a method of manufacturing of the example helmet, in accordance with an embodiment. In block <NUM>, the outer shell of the helmet can be formed. The outer shell can be formed from plastics, composites, and/or other materials appropriate for a hard outer shell of a helmet via lay-up, vacuum forming, injection molding, and/or another appropriate process.

In block <NUM>, liners of the helmet are formed. Liners can be formed of any suitable material, including energy absorbing materials such as expanded polystyrene (EPS) or expanded polypropylene (EPP). Further, additional components (e.g., dampers, rivets, carriers) can be formed and/or obtained in block <NUM>.

The liners and components can be assembled in block <NUM> by fastening together, gluing, and/or other coupling via other techniques the liners and/or components. The internal components of the helmet can then be coupled to the outer shell in block <NUM> (e.g., via Velcro™ padding, adhesives, fasteners, and/or other techniques) to form a complete helmet. In certain embodiments, assembling certain liner(s) and/or other component(s) can form liner assemblies. Such liner assemblies can then be coupled to multiple other parts and/or assemblies to form a complete helmet.

Other embodiments of the impact absorbing system may include any of the impact absorbing system configurations detailed herein in various safety helmets (e.g., sports helmets, construction helmets, racing helmets, helmets worn by armed forces personnel, helmets for the protection of people such as toddlers, bicycle helmets, pilot helmets, and other helmets) as well as in various other safety equipment designed to protect a wearer. Non-limiting examples of such other safety equipment may include body armor such as vests, jackets, and full body suits, gloves, elbow pads, shin pads, hip pads, shoes, helmet protection equipment and knee pads, but these do not form part of the claimed invention.

Claim 1:
A helmet (<NUM>) comprising:
an outer shell (<NUM>);
a first liner (<NUM>) disposed within and coupled to the outer shell, the first liner comprising a first protrusion (<NUM>) and a second protrusion (<NUM>), wherein the first protrusion has a first end disposed on a side of the first liner facing away from the outer shell;
a second liner (<NUM>) comprising a first material and disposed within and coupled to the first liner, wherein the second protrusion faces the second liner;
a polymer liner (<NUM>) comprising a second material different from the first material, coupled to the second liner, and disposed between the first liner and the second liner; and
a first pad (<NUM>) coupled to the first end of the first protrusion, wherein a first coefficient of friction between the first pad and the polymer liner is less than a second coefficient of friction between the second protrusion and the polymer liner.