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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be better understood by those skilled in the art from the following detailed description of illustrative embodiments taken in conjunction with the accompanying drawings in which:

FIG. 1 is a typical Force/Time curve for an impact-absorbing material, showing the force transmitted by the material as a function of time;

FIG. 2 is a Force/Time curve for a foam material that is too “soft” for the impact applied to the foam;

FIG. 3 is a series of Force/Time curves for a foam material that is too “hard” for a given impact (i.e., Trial 1) applied to the foam;

FIG. 4 shows two Force/Time curves for a given foam illustrating the change in the performance of the foam in response to different impact energies;

FIG. 5 is a series of Force/Time curves for a foam material illustrating the decline in the performance of the foam as a result of repeated impacts;

FIG. 6 is a side view, partly in section, of a compressible cell embodied in accordance with the invention;

FIG. 7 is a top view of the cell of FIG. 6, illustrating its generally round, symmetrical shape and configuration;

FIG. 8 is a Force/Time curve for a cell such as that shown in FIG. 6, illustrating how the cell can be customized to produce a nearly trapezoidal and flattened force response;

FIG. 9 shows two Force/Time curves for a cell such as that shown in FIG. 6, illustrating the response of the cell to two different impact energies;

FIG. 10 shows a Force/Time curve for a compressible cell having a saucer shape, with no initially resistive mechanism;

FIG. 11 shows a Force/Time curve for a compressible cell having bellows-like side walls, again with no initially resistive mechanism;

FIG. 12 is a schematic illustration showing a cross section and geometric details of a preferred cell embodied in accordance with the invention;

FIG. 13 is a schematic illustration showing cross sections of other cell shapes potentially suitable for the invention;

FIG. 14 is a side view, partly in section, of a second embodiment of the invention in which the initially resistive mechanism comprises a resiliently collapsible ring positioned inside the cell;

FIG. 15 is a side view, partly in section, of a third embodiment of the invention in which a cell such as that shown in FIG. 6 is combined with foam base plate to enhance the shock-absorbing response and durability of the cell;

FIG. 16 is a side view of a fourth embodiment of the invention in which a cell such as that shown in FIG. 6 is combined with a second cell of similar construction;

FIG. 17 shows a plurality of cells such as the cells shown in FIGS. 6, 14, 15 or 16 arranged side-by-side to form a middle layer of a multilayered protective structure having an outer shell and an inner layer.

Claims

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; andproviding 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, 3, 4 or 5 in which the second impact-absorbing mechanism is provided by providing the cell with at least one orifice which vents fluid from inside the cell after the initial phase of the impact.

7. The method of claim 6 in which the at least one orifice allows fluid to return to the cell after the impact.

8. 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; anda 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.

9. The system of claim 8 in which said protective structure comprises at least one fluid-containing, compressible cell.

10. The system of claim 9 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.

11. The system of claim 9 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.

12. The system of claim 11 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.

13. The system of claim 9, 10, 11 or 12 in which said second impact-absorbing mechanism comprises at least one orifice in said cell which vents fluid from said cell after the initial phase of the impact.

14. The system of claim 9 in which said cell has a substantially symmetrical shape.

15. The system of claim 13 in which the at least one orifice allows fluid to return to the cell after the impact.

16. 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.

17. 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.

18. The protective structure of claim 16 in which said impact-absorbing mechanism comprises a component that coacts with said enclosure to resist collapse during the initial phase of the impact and to collapse after the initial impact phase.

19. The protective structure of claim 18 in which said component comprises a collapsible ring disposed in the inner chamber of said enclosure.

20. The protective structure of claim 16 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.

21. The protective structure of claim 16 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.

22. The protective structure of claim 16 in which said enclosure has a substantially symmetrical shape.

23. The protective structure of claim 16 further including a layer of foam joined to said enclosure.

24. The protective structure of claim 16 in which said enclosure is joined to a second substantially similar enclosure.

25. The protective structure of claim 23 in which said layer of foam defines an aperture that allows fluid to flow through said layer as it vents from said at least one orifice in said enclosure during the impact.

26. The protective structure of claim 16 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.

27. The protective structure of claim 26 wherein said plurality of enclosures is disposed between said at least one additional layer and a second layer.

28. The protective structure of claim 16 in which said enclosure has a disk shape with circular top and bottom surfaces of diameter d1.

29. The protective structure of claim 28 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 d2 which is greater than d1.

30. The protective structure of claim 29 in which said first and second side wall portions of said enclosure are substantially straight in cross section.

31. The protective structure of claim 30 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.

32. The protective structure of claim 29 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.

33. The protective enclosure of claim 29 further including at least one orifice through one of said top and bottom surfaces of said enclosure.

34. The protective enclosure of claim 33 in which said at least one orifice has a diameter in the range of about 1.00 millimeter to about 5.00 millimeters.

35. The protective structure of claim 16 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.

36. The protective structure of claim 35 in which said enclosure is symmetrical about a medial plane parallel to said top and bottom walls.

37. The protective structure of claim 35 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.

38. The protective structure of claim 37 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.

39. The protective structure of claim 38 in which the points B and B′ in said pattern are equidistant between the points A and C and A′ and C′, respectively.

40. 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, andproviding the protective covering with an impact-absorbing structure that resists yeilding in the 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 force of the impact after said maximum force value is reached such that said curve thereafter remains substantially constant throughout the remainder of the impacts.

41. 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, andan impact-absorbing structure in said protective covering that resist yeiding 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 force of the impact after said maximum force value is reached such that said curve thereafter remains substantially constant throughout the remainder of the impact.

42. The system defined in claim 41 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.

43. The system defined in claim 42 wherein each cell has an orifice which vents fluid from that cell after the initial impact phase.