Energy dissipating breakaway assembly for protective helmet

Abstract

A protective helmet, which includes a motion restrictor device, is disclosed. The device includes a strut having a pair of relatively moveable strut members. One of the strut members is associated with the helmet, and the other strut member is associated a harness assembly. The device also includes a brake assembly, with the assembly providing a plurality of arrest rates. Each of the arrests rates corresponds with a rate of relative motion (or acceleration) and a corresponding force experienced between the pair of strut members.

What is claimed is: 
     
         1 . A motion restrictor device for use with a protective helmet to reduce the risk of head or spine injury caused by injurious movement of the helmet, said motion restrictor device comprising:
 a harness wearable by a user of the helmet;   a strut presenting first and second ends, with the first end of the strut adapted to be associated with the protective helmet and the second end of the strut operably coupled to the harness,   said strut permitting relative motion between the first and second ends thereof; and   a decelerator configured to affect relative motion between the ends of the strut in response to the injurious movement and absorb a load experienced by the strut when the load exceeds a load threshold,   said decelerator being operable to stop at least substantially all motion between the ends of the strut in response to the injurious movement when the load experienced by the strut is below the load threshold,   said decelerator being operable to at least partly absorb the load experienced by the strut and permit restricted motion between the ends thereof when the load experienced by the strut is above the load threshold.   
     
     
         2 . The motion restrictor device as claimed in  claim 1 ,
 said decelerator being activated to stop at least substantially all motion between the ends of the strut when the relative motion between the ends exceeds a velocity threshold.   
     
     
         3 . The motion restrictor device as claimed in  claim 2 ,
 said decelerator including a plurality of spaced apart stops,   said decelerator including a shiftable brake element that shifts into braking engagement with at least one of the stops when the decelerator is activated.   
     
     
         4 . The motion restrictor device as claimed in  claim 3 ,
 said stops being arranged in a circular pattern so as to be circumferentially spaced apart,   said brake element shifting radially into engagement with at least one of the stops when the decelerator is activated.   
     
     
         5 . The motion restrictor device as claimed in  claim 4 ,
 said brake element rotating in response to relative motion between the ends of the strut,   said brake element being shifted by centrifugal force into engagement with at least one of the stops when the relative motion between the ends of the strut exceeds the velocity threshold.   
     
     
         6 . The motion restrictor device as claimed in  claim 5 ,
 said brake element being located radially inside the stops.   
     
     
         7 . The motion restrictor device as claimed in  claim 1 ,
 said decelerator including a plurality of spaced apart breakaway members,   said decelerator including a shiftable component that has shifted into engagement with at least one of the breakaway members when the load experienced by the strut exceeds the load threshold,   each of said breakaway members including a fracture zone,   said decelerator being configured so that each breakaway member engaged by the shiftable component at least partly fractures when the load experienced by the strut exceeds the load threshold.   
     
     
         8 . The motion restrictor device as claimed in  claim 7 ,
 said fracture zone being defined by an area of weakness.   
     
     
         9 . The motion restrictor device as claimed in  claim 8 ,
 each of said breakaway members being elongated and presenting a variable cross-sectional dimension,   said area of weakness being defined by at a relatively reduced cross-sectional dimension.   
     
     
         10 . The motion restrictor device as claimed in  claim 9 ,
 said shiftable component being configured to engage the breakaway members at the reduced cross-sectional dimension.   
     
     
         11 . The motion restrictor device as claimed in  claim 9 ,
 said decelerator including an elongated body,   each breakaway element projecting from the body to a tip spaced from the body,   each breakaway element tapering from the tip toward the body so that the reduced cross-sectional dimension is spaced from the tip.   
     
     
         12 . The motion restrictor device as claimed in  claim 11 ,
 said elongated body comprising an annular body,   said breakaway elements being arranged in a circular pattern along the annular body so as to be circumferentially spaced apart,   said shiftable component shifting radially into engagement with at least one of the breakaway elements when the decelerator is activated.   
     
     
         13 . The motion restrictor device as claimed in  claim 12 ,
 said breakaway elements each projecting radially inwardly from the body to the tip,   said breakaway elements each presenting opposite element faces that face circumferentially to be engaged by the shiftable component.   
     
     
         14 . The motion restrictor device as claimed in  claim 13 ,
 each of said breakaway elements tapering so that the reduced cross-sectional dimension is located where the breakaway elements meet the annular body.   
     
     
         15 . The motion restrictor device as claimed in  claim 14 ,
 said annular body presenting a radially inner surface,   said element faces intersecting the radially inner surface to cooperatively define the reduced cross-sectional dimension.   
     
     
         16 . The motion restrictor device as claimed in  claim 8 ,
 said shiftable component comprising a brake element and each breakaway element comprising a stop, with interengagement between the brake element and at least one of the stops cooperatively preventing at least substantially all motion between the ends of the strut when the load experienced by the strut is below the load threshold.   
     
     
         17 . The motion restrictor device as claimed in  claim 16 ,
 said decelerator being activated to shift the braking element into engagement with at least one of the stops when the relative motion between the ends of the strut exceeds a velocity threshold.   
     
     
         18 . The motion restrictor device as claimed in  claim 17 ,
 said stops being arranged in a circular pattern so as to be circumferentially spaced apart,   said brake element shifting radially into engagement with at least one of the stops when the decelerator is activated.   
     
     
         19 . The motion restrictor device as claimed in  claim 18 ,
 said brake element rotating in response to relative motion between the ends of the strut,   said brake element being shifted by centrifugal force into engagement with at least one of the stops when the relative motion between the ends of the strut exceeds the velocity threshold.   
     
     
         20 . The motion restrictor device as claimed in  claim 7 ,
 said shiftable component being configured to engage only one of the breakaway members at a time, with the breakaway members being consecutively fractured until the load experienced by the strut is absorbed to a level below the load threshold.   
     
     
         21 . The motion restrictor device as claimed in  claim 2 ,
 said decelerator including a housing, a shiftable brake element, and a removable stop component,   said decelerator including a shiftable brake element that is shiftably mounted relative to the housing,   said brake element shifting into braking engagement with the removable stop component when the decelerator is activated.   
     
     
         22 . The motion restrictor device as claimed in  claim 21 ,
 said shiftable brake element drivingly connected relative to the strut such that the brake element shifts in response to relative movement between the helmet and the harness,   said removable stop component including an elongated body and a plurality of stops spaced along the length of body.   
     
     
         23 . The motion restrictor device as claimed in  claim 22 ,
 said elongated body comprising an annular body,   said stops being arranged in a circular pattern along the annular body so as to be circumferentially spaced apart,   said brake element shifting radially into engagement with at least one of the stops when the decelerator is activated.   
     
     
         24 . The motion restrictor device as claimed in  claim 23 ,
 said housing comprising a receiver,   said receiver forming a generally cylindrical opening that receives the removable stop component when the removable stop component is mounted,   said removable stop component being shiftable into and out of the cylindrical opening.   
     
     
         25 . The motion restrictor device as claimed in  claim 24 ,
 said body including one of a male holding element and a female holding element,   said receiver presenting the other of the male holding element and the female holding element, with the holding elements being interengaged to cooperatively restrict stop rotation when the stop is mounted on the receiver.   
     
     
         26 . The motion restrictor device as claimed in  claim 22 ,
 each of said stops including a fracture zone,   said decelerator being configured so that each stop engaged by the shiftable brake element at least partly fractures when the load experienced by the strut exceeds the load threshold,   said removable stop component being removable from the housing when at least one of the stops is fractured.   
     
     
         27 . The motion restrictor device as claimed in  claim 26 ,
 said fracture zone being defined by an area of weakness.   
     
     
         28 . The motion restrictor device as claimed in  claim 27 ,
 each of said stops being elongated and presenting a variable cross-sectional dimension,   said area of weakness being defined at a relatively reduced cross-sectional dimension.   
     
     
         29 . The motion restrictor device as claimed in  claim 28 ,
 said brake element being configured to engage the stops at the reduced cross-sectional dimension.