Multi-shell helmet with pivotable outer shell

Abstract

Helmet prevent or mitigate cervical spine fractures, including the type of injuries associated with axial compression of the spine and fracture of the spine which may otherwise result in deformation and/or injury to the spinal cord. Helmets convert an impact force with a component aligned with the axis of the spine (a “spinally axial component”) to rotational motion. In the event of a head-first impact, such helmets flexion of the neck so that the head and the cervical spine are not aligned (or less aligned) with the direction of an impact force, thereby mitigating the likelihood and/or severity of cervical spine fractures.

1 .- 20 . (canceled) 
     
     
         21 . A helmet comprising:
 an outer shell defining a concavity;   an inner member, at least a portion of which is located within the concavity, the inner member pivotally coupled to the outer shell and permitted to move relative to the outer shell by rotation about a laterally oriented pivot axis;   one or more pivot joints which facilitate relative pivotal movement between the inner member and the outer shell about the laterally oriented pivot axis and constrain relative movement between the inner member and outer shell to movement about the laterally oriented pivot axis; and   a deployment device which:   in the absence of sufficient external force, constrains rotational motion between the inner member and the outer shell about the pivot axis; and   when the helmet receives an impact having sufficient force, deploys to permit relative angular rotation between the outer shell and the inner member about the pivot axis.   
     
     
         22 . The helmet as defined in  claim 21  wherein the deployment device constrains the relative rotational motion between the inner member and the outer shell, in the absence of sufficient external force, by applying force that tends to prevent relative rotation between the inner member and the outer shell or between any components of the pivotal coupling between the inner member and the outer shell. 
     
     
         23 . The helmet as defined in  claim 21  wherein, in the absence of sufficient external force, the deployment device constrains rotational motion between the inner member and the outer shell about the pivot axis to a minimum relative rotation. 
     
     
         24 . The helmet as defined in  claim 23 , wherein when the helmet receives an impact having sufficient force, the deployment device deploys to permit a larger range of relative angular rotation between the outer shell and the inner member about the pivot axis. 
     
     
         25 . The helmet as defined in  claim 21 , wherein the laterally oriented pivot axis is parallel to a lateral plane and orthogonal to a mid-sagittal plane of the helmet. 
     
     
         26 . The helmet as defined in  claim 25 , wherein the laterally oriented pivot axis passes a coupling zone bounded by three notional lines in the mid-sagittal plane of the helmet, the three lines being:
 a center of gravity line;   a brow line running from a front portion to a back portion of the helmet and tangential to a lowermost point on a surface that defines a top edge of a face opening; and   an anterior line parallel to the center of gravity line and intersecting the lowermost point of the top edge surface of the face opening.   
     
     
         27 . The helmet as defined in  claim 21 , wherein the inner member and outer shell are coupled together by the one or more pivot joints. 
     
     
         28 . The helmet as defined in  claim 21 , wherein the one or more pivot joints comprise two pivot mechanisms located symmetrically on the helmet. 
     
     
         29 . The helmet as defined in  claim 28 , wherein one or both of the two pivot mechanisms are positioned between a center of gravity line of the helmet and a position where a maximal relative angular rotation range between the inner member and the outer shell after deployment of the deployment device is in a range of 10°-30°. 
     
     
         30 . The helmet as defined in  claim 27 , wherein the inner member and the outer shell are coupled together by engagement of a pin through a pair of aligned apertures in the inner member and the outer shell. 
     
     
         31 . The helmet as defined in  claim 21 , the deployment device comprising a shear pin, wherein the shear pin shears and breaks when the helmet receives the impact force greater than a configurable threshold. 
     
     
         32 . The helmet as defined in  claim 21 , the deployment device comprising an elastic attachment member connected between the inner member and the outer shell, wherein when the helmet receives the impact, the elastic attachment member deforms to permit relative rotation of the inner member and the outer shell about the laterally oriented pivot axis. 
     
     
         33 . The helmet as defined in  claim 21 , wherein the one or more pivot joints and the deployment device are separate from each other. 
     
     
         34 . The helmet as defined in  claim 21 , wherein the deployment device is provided as part of at least one of the one or more pivot joints that permits relative rotational movement between the inner member and outer shell about the pivot axis. 
     
     
         35 . The helmet as defined in  claim 21 , further comprising a cushioning layer positioned between the inner member and the outer shell, the cushioning layer configured to control rotational acceleration or deceleration of outer shell relative to inner member. 
     
     
         36 . The helmet as defined in  claim 21 , wherein the outer shell comprises one or more beveled regions. 
     
     
         37 . The helmet as defined in  claim 21 , wherein a mid-sagittal plane of the outer shell comprises one of more apexes. 
     
     
         38 . The helmet as defined in  claim 21 , wherein:
 the outer shell comprises one or more beveled regions, each beveled region defined by a pair of corresponding apexes on a mid-sagittal plane of the outer shell; and   the apexes interact with an impact surface to increase the torque (relative to a round surface) experienced by the outer shell as a result of the interaction between the outer shell and the impact surface.   
     
     
         39 . The helmet as defined in  claim 21 , further comprising a protective liner attached to an inner surface of the inner member. 
     
     
         40 . The helmet as defined in  claim 21 , wherein at least one of the outer shell and the inner member is shaped to cover at least one of a crown region, a front region and a back region of a wearer's head. 
     
     
         41 . The helmet as defined in  claim 21 , wherein the deployment device is positioned at the back of the helmet.