Impact energy management method and system

Abstract

An impact-absorbing protective structure comprises one or more compressible cells. Each cell is in the form of a thin-walled plastic enclosure defining an inner, fluid-filled chamber with at least one small orifice through which fluid resistively flows. Each cell includes an initially resistive mechanism that resists collapse during an initial phase of an impact and that then yields to allow the remainder of the impact to be managed by the venting of fluid through the orifice. The initially resistive mechanism may be implemented by providing the cell with semi-vertical side walls of an appropriate thickness or by combining a resiliently collapsible ring with the cell. After the initially resistive mechanism yields to the impact, the remainder of the impact is managed by the fluid venting through the orifice. The cell properties can be readily engineered to optimize the impact-absorbing response of the cell to a wide range of impact energies.

1 . An impact energy management method for protecting a body from damage due to impacts imparted thereto, the method comprising the steps of:
 placing a protective structure over at least a portion of the body to be protected, the protective structure being capable of reducing forces of an impact that are transferred to the body through the protective structure;   providing the protective structure with a first impact-absorbing mechanism that resists yielding in response to an initial phase of the impact and that yields to the impact after the initial phase of the impact; and   providing the protective structure with a second impact-absorbing mechanism that attenuates the forces of the impact after its initial phase such that the forces that are transferred to the body remain substantially constant throughout the remainder of the impact.   
     
     
         2 . The method of  claim 1  in which the placing step comprises placing a protective structure that includes at least one fluid-containing, compressible cell over the portion of the body to be protected. 
     
     
         3 . The method of  claim 2  in which the first impact-absorbing mechanism is provided by providing the cell with side walls designed so that they resist collapse during the initial phase of the impact and collapse after the initial impact phase. 
     
     
         4 . The method of  claim 2  in which the first impact-absorbing mechanism is provided by combining the cell with a component that coacts with the cell to resist collapse during the initial phase of the impact and to collapse after the initial impact phase. 
     
     
         5 . The method of  claim 4  in which the first impact-absorbing mechanism is provided by including a collapsible ring inside the cell that resists collapse during the initial phase of the impact and that collapses after the initial impact phase. 
     
     
         6 . The method of  claim 2  in which the at least one orifice allows fluid to return to the cell after the impact. 
     
     
         7 . An impact energy management system for protecting a body from damage due to impacts imparted thereto, the system comprising:
 a protective structure adapted to be placed over at least a portion of the body to be protected, said protective structure being capable of reducing forces of an impact that are transferred to the body through said protective structure;   a first impact-absorbing mechanism in said protective structure that resists yielding in response to an initial phase of the impact and that yields to the impact after the initial phase of the impact; and   a second impact-absorbing mechanism in said protective structure that attenuates the forces of the impact after its initial phase such that the forces that are transferred to the body remain substantially constant throughout the remainder of the impact.   
     
     
         8 . The system of  claim 7  in which said protective structure comprises at least one fluid-containing, compressible cell. 
     
     
         9 . The system of  claim 8  in which said first impact-absorbing mechanism comprises side walls on said cell that are oriented and configured so that they resist collapse during the initial phase of the impact and that collapse after the initial impact phase. 
     
     
         10 . The system of  claim 8  in which said first impact-absorbing mechanism comprises a component that coacts with said cell to resist collapse during the initial phase of the impact and to collapse after the initial impact phase. 
     
     
         11 . The system of  claim 10  in which said first impact-absorbing mechanism comprises a collapsible ring inside said cell that resists collapse during the initial phase of the impact and that collapses after the initial impact phase. 
     
     
         12 . The system of  claim 8  in which said cell has a substantially symmetrical shape. 
     
     
         13 . The system of  claim 8  in which the at least one orifice allows fluid to return to the cell after the impact. 
     
     
         14 . A protective structure for protecting a body from impact comprising:
 at least one thin-walled enclosure having an uncompressed configuration which defines a hollow inner chamber;   a volume of fluid at least partially filling said inner chamber;   at least one orifice through said enclosure that resistively vents fluid from the inner chamber in response to an impact on said enclosure;   an impact-absorbing mechanism associated with said enclosure that resists yielding in response to an initial phase of the impact on said enclosure and that yields to the impact after the initial phase of the impact to allow the remainder of the impact to be managed by the fluid venting from said at least one orifice.   
     
     
         15 . The protective structure of  claim 16  in which said impact-absorbing mechanism comprises side walls on said enclosure that are oriented and configured so that they resist collapse during the initial phase of the impact and that collapse after the initial impact phase. 
     
     
         16 . The protective structure of  claim 14  in which said enclosure and said at least one orifice through said enclosure are sized and configured so that forces transferred through said structure remain substantially constant after the initial phase of the impact. 
     
     
         17 . The protective structure of  claim 14  in which said at least one orifice permits an inflow of fluid into the inner chamber of said enclosure to return said enclosure to its uncompressed configuration after the impact. 
     
     
         18 . The protective structure of  claim 14  in which said enclosure has a substantially symmetrical shape. 
     
     
         19 . The protective structure of  claim 14  further including a body of foam joined to said enclosure. 
     
     
         20 . The protective structure of  claim 14  in which said enclosure is joined to a second substantially similar enclosure. 
     
     
         21 . The protective structure of  claim 14  comprising a plurality of said enclosures arranged side-by-side in a layer and at least one additional layer joined to corresponding parts of said enclosures. 
     
     
         22 . The protective structure of  claim 21  wherein said plurality of enclosures is disposed between said at least one additional layer and a second layer. 
     
     
         23 . The protective structure of  claim 14  in which said enclosure has a disk shape with circular top and bottom surfaces of diameter d 1 . 
     
     
         24 . The protective structure of  claim 23  in which said enclosure includes a first side wall portion extending from said top surface and a second side wall portion extending from said bottom surface, said first and second side wall portions joining at a medial plane through said enclosure of diameter d 2  which is greater than d 1 . 
     
     
         25 . The protective structure of  claim 24  in which said first and second side wall portions of said enclosure are substantially straight in cross section. 
     
     
         26 . The protective structure of  claim 25  in which said first side wall portion extends at an angle from said top surface, and said second side wall portion extends at substantially the same angle from said bottom surface, said angle being greater than zero degrees and less than 45 degrees. 
     
     
         27 . The protective structure of  claim 24  in which said enclosure is formed of a thermoplastic elastomer material having a wall thickness in the range of about 1.00 millimeter to about 3 millimeters. 
     
     
         28 . The protective enclosure of  claim 24  further including at least one orifice through one of said top and bottom surfaces of said enclosure. 
     
     
         29 . The protective enclosure of  claim 28  in which said at least one orifice has a diameter in the range of about 1.00 millimeter to about 5.00 millimeters. 
     
     
         30 . The protective structure of  claim 14  in which said enclosure has generally parallel top and bottom walls and is symmetrical about a central axis passing through said enclosure normal to said top and bottom walls. 
     
     
         31 . The protective structure of  claim 30  in which said enclosure is symmetrical about a medial plane parallel to said top and bottom walls. 
     
     
         32 . The protective structure of  claim 30  in which said enclosure further includes a first side wall portion extending from said top wall and a second side wall portion extending from said bottom wall, said first and second side wall portions joining at the medial plane. 
     
     
         33 . The protective structure of  claim 32  wherein said walls of said enclosure, in side cross section, pass through spaced points A, B, C, A′, B′, C′, said points being in a pattern such that a line between A and A′ is in a plane corresponding to said top wall, a line between C and C′ is in a plane corresponding to said bottom wall, and a line between B and B′ is in a medial plane parallel to said top wall and said bottom wall. 
     
     
         34 . The protective structure of  claim 33  in which the points B and B′ in said pattern are equidistant between the points A and C and A′ and C′, respectively. 
     
     
         35 . An impact energy management method for protecting a body from damage due to impacts imparted thereto, the method comprising the steps of:
 placing a protective covering over at least one portion of the body to be protected, the protective covering being capable of reducing forces of an impact in accordance with a force/time curve, and   providing the protective covering with an impact-absorbing structure that resists yielding in response to an initial phase of the impact so that said curve has a relatively steep leading edge which rises to a maximum force value determined by the impact and then attenuates the forces of the impact after said maximum force value is reached such that said curve thereafter remains substantially constant throughout the remainder of the impact.   
     
     
         36 . An impact management system for protecting a body from damage due to impacts imparted thereto, the system comprising:
 a protective covering adapted to be placed over at least a portion of the body to be protected, said protective covering being capable of reducing forces of an impact in accordance with a force/time curve, and   an impact-absorbing structure in said protective covering that resist yielding in response to an initial phase of the impact so that said curve has a relatively steep leading edge which rises to a maximum force value determined by the impact, and then attenuates the forces of the impact after said maximum force value is reached such that said curve thereafter remains substantially constant throughout the remainder of the impact.   
     
     
         37 . The system defined in  claim 36  wherein said impact-absorbing structure comprises at least one fluid-containing compressible cell with side walls arranged and adapted to resist collapse during the said initial phase of the impact and to collapse after said initial impact phase. 
     
     
         38 . A protective structure for protecting a body from impact comprising a thin-walled enclosure having an uncompressed configuration which defines a hollow inner chamber, said enclosure including a single pair of substantially frustoconical side walls connected back to back so as to define an obtuse included angle between them, an end wall closing one end of the enclosure, and a base plate closing the other end of the enclosure. 
     
     
         39 . The protective structure of  claim 38  wherein the base plate comprises a plastic wall. 
     
     
         40 . The protective structure of  claim 38  wherein the base plate includes an exterior resilient pad. 
     
     
         41 . The protective structure of  claim 38  wherein the base plate includes a connection surface for connecting the enclosure to a support surface. 
     
     
         42 . The protective structure of  claim 38  wherein the obtuse included angle is an interior included angle. 
     
     
         43 . The protective structure of  claim 28  wherein the obtuse included angle is an exterior included angle.