It is known, for example from GB 2 367 877, to provide an impact-absorbing unit in which an outer casing houses impact-absorbing material in the form of a loose fill of compressible particles. In such a unit the force of an impact is received directly by the impact-absorbing material, and the force is concentrated at the point of impact. Such a system is shown in Figure 1 of the drawings, in which an impact-absorbing unit is generally indicated 1 and comprises an outer casing 2 housing a loose fill of expanded polystyrene particles 3 constituting the impact- absorbing material. An object 4 is shown in phantom impacting the unit 1. The force of the impact is received directly by the impact-absorbing material 3 and this force is concentrated initially at a single point. The force of the impact is dissipated as the object 4 compresses the particles 3 and causes them to move.

Because the level of resistance to the force of the impact presented by the material 3 is substantially the same throughout the unit 1, the resistance cannot be too high without risk of the object bouncing off the unit or being damaged by the impact on the unit 1 itself. Coupled with the fact that the force of the impact is concentrated at a single point, it is possible that with a sufficiently large force the object 4 will compress and move the particles 3 to such an extent that the object 4 compresses the unit 1 to the extent that it reaches the opposite side of the casing before the force of impact has been fully dissipated. It would be possible in these circumstances that the object 4 could impact a hard surface upon which the unit 1 is standing with sufficient remaining force to cause damage.

The present invention seeks to address the problems with the prior art described above.

According to a first aspect of the present invention, there is provided an impact- absorbing unit comprising: an outer casing; impact-absorbing material housed within the outer casing; and an impact member for receiving the force of an impact and distributing it to the impact-absorbing material.

In other words, the present invention provides a unit for absorbing impacts which resists excessive compression whilst dissipating the force of an impact is provided. An outer casing houses material for absorbing impact force and an impact member is provided to reinforce the unit. The impact member receives the impact force and in addition to absorbing part of the force it distributes a reduced load to the material so as to spread the region of compression over a greater area of the unit.

The impact member of the present invention therefore serves to receive the force of an impact and spread the force over a greater area of impact-absorbing material. The impact force is therefore dissipated over a wider area of impact-absorbing material which in turn reduces the compression of the impact-absorbing unit in the direction of the impact force. This system therefore reduces the chances of an object compressing the unit to the extent that it impacts the surface upon which the unit is standing. The addition of the impact member therefore allows the thickness of the impact-absorbing unit to be reduced whilst providing the same level of impact absorbance. This also means that the unit of the present invention is suitable for use in situations where objects may impact with high velocity and high impact forces. One example of the utility of the present invention is for use as part of a crash barrier on a motor racing circuit such as a speedway ring. The present invention may also find utility on building construction sites where they could be laid to protect individuals or equipment from falls.

According to a second aspect of the present invention there is provided: an outer casing; impact-absorbing material housed within the outer casing; and an impact member forming a region of increased rigidity positioned such that, in use, it receives the force of an impact prior to the impact-absorbing material.

By providing a region of increased rigidity the unit is reinforced against the impact force. The level of force which is received by the impact-absorbing material is reduced and the likelihood of the impacting object compressing the unit fully is reduced. The impact member serves the purposes of reinforcing the unit to reduce compression and distributing the load of an impact more evenly to a greater area of impact-absorbing material. According to a third aspect of the present invention there is provided a fall arrest unit comprising: an outer casing including one or more impact surfaces for receiving a falling object; impact-absorbing material housed within the outer casing; and an impact member associated with the or each impact surface for receiving the force of an impact in preference to the impact-absorbing material and distributing it to the impact-absorbing material.

The impact member may be at least partly resilient, whereby itself to absorb at least some of the force of an impact. The impact member is therefore at least partly compliant to allow the force to be distributed and dissipated. In some embodiments, the impact member is flexible.

The impact member may comprise a substantially laminar panel. Such a laminar panel would be easy to manufacture and to associate with the outer casing of the impact-absorbing unit. In addition, a laminar panel with a unitary thickness would allow substantially even distribution of an impact force from the impact site.

The impact member may be housed within the outer casing. In this way, the impact member is protected from damage or separation from the remainder of the unit. Alternatively, the impact member may be external to the outer casing, which would allow it to be easily fitted to new units or retro-fitted to existing units. The impact member may comprise at least part of the outer casing. Accordingly the outer casing may itself be the impact member. In other embodiments the impact member forms an integral part of the outer casing.

Particularly in cases where the impact-absorbing material is a loose fill of material, such as polystyrene granules, the material may migrate within the outer casing; for example, if the material is held directly by the outer casing or if it was held in an internal bag which ruptured it would be free to move. If the impact member is internal to the outer casing then it will preferably be adjacent the outer casing in order to function with maximum efficiency. There is therefore a risk that impact- absorbing material could migrate and intervene between the casing and the impact member. This could occur following impact/s or simply as the unit was moved around. As a result the unit may be provided with retaining means for holding the impact member in a required location. The retaining means may comprise, for example, a pocket formed in the outer casing or one or more straps.

The retaining means preferably allows some freedom of movement so that during an impact it is not caused to break. If, for example, an adhesive is used then it should not allow the member to be torn away from the casing during an impact resulting from the deformation of the casing and the member.

It has been found by the inventors that an impact member comprising a sheet of extruded polyethylene is particularly suitable. The impact-absorbing unit may be formed so as to be capable of being placed together in a closely adjacent relationship with one or more further such units to define a substantially continuous impact surface. A plurality of such units could therefore be placed together to form an impact surface of required dimensions.

The outer casing may comprise at least one substantially flat surface to facilitate the placement of the unit in closely adjacent relationship with another such unit.

The impact- absorbing material may be compressible and may comprise a loose fill of substantially compressible granules, such as polystyrene granules.

The impact-absorbing material may comprise one or more flexible envelopes housing a fluid. The fluid may comprise a gas, for example air.

The unit may be provided with interconnection means for interconnection with one or more other such units. The interconnection means may be arranged to allow interconnection of respective units to allow stacking of units to increase the absorbent capacity of an impact surface.

The impact member may form at least part of the interconnection means. For example, the interconnection means may be formed on the exterior of a plurality of units and span across them. The interconnection means may comprise a clasp or the like. The clasp or the like may be positioned at the free ends of external straps secured to the outer casing at either end to form a handle.

In order to allow for manipulation of the unit it may further comprise a handle portion. The outer casing may be perforated to allow the passage of air therethrough. Exhaustion of air from the unit can be used to help with dissipation of the impact force energy.

The outer casing may be formed from a plurality of panels. The panels may be formed to assume a naturally convex shape when assembled to form the outer casing. In such embodiments once the inner impact-absorbing means is added to the outer casing the panels will be pushed outwardly from their initial convex form to give substantially flat surfaces rather than concave surfaces, which could be the case if the panels were initially flat.

The selection of materials for and the form of such a fall arrest unit is of particular importance if it is to function as required. For example, if the fall arrest unit is intended to be used on a building construction site the unit will likely be subjected to a large amount of wear and tear. An outer casing formed from a substantially wear-resistant material would therefore be advantageous. The outer casing may be formed from or treated with a water-resistant material. This is particularly useful if the fall arrest unit is intended for use on a building construction site. Alternatively or additionally, the outer casing may be formed from or treated with a fire-resistant material to enable its use in a wide range of circumstances.

The outer casing may be formed from woven polypropylene. The material may result in a wear-resistant casing which is durable and suitable for use, for example, in the construction industry.

The unit may be required to absorb impact indefinitely and in this case would preferably retain a predetermined shape. The outer casing panels may be secured together at their peripheries in such a way that the peripheral connections serve to assist in retaining a predetermined shape. The predetermined shape may comprise substantially flat faces. The panels may be secured edge to edge to form a projecting ridge in the form of a stiffened rib. The panels may be secured together by stitching; and the thread used for stitching is preferably high strength, typically 5000 denier, 7 grams per denier polypropylene.

It is noted that stitching can usefully be employed other than for purposes of sealing panels together. For example, if stitching is used at corners and along edges of a unit regardless of whether this is required for sealing the stitching also serves a protective function. This function may be enhanced by judicious choice of the stitch type; overlock chain stitch is preferred. The unit may be of substantially parallelepiped form. Such a unit may comprise an outer casing formed from two major panels each defining two adjacent major surfaces of a parallelepiped, and two opposing rectangular end panels.

The unit may have dimensions of a multiple of approximately one third of a metre as this is a standard measurement in the building industry and will allow the unit to fit easily within the dimensions of a construction.

The impact-absorbing unit may also comprise an outer sheath which substantially surrounds the outer casing and the impact member.

The outer sheath may be formed from a sheet of plastics material, such as polyvinyl chloride (PVC), which wraps around one or more units, protecting them and helping to hold them together.

In embodiments where the impact member is external to the outer casing the sheath may be used to hold the impact member in place relative to the outer casing.

The present invention also provides an impact-absorbing structure comprising a plurality of impact-absorbing units as described above arranged in a closely adjacent relationship.

The plurality of units may be arranged in a single layer, or in stacked layers for increased impact absorbing capacity. The present invention also provides a fall arrest system for cushioning the fall of a person in the construction industry, comprising a plurality of impact-absorbing units as described above arranged together in a closely adjacent relationship to define a substantially continuous impact surface on which to receive a falling person.

The present invention also provides a lateral impact-absorbing unit comprising: an outer casing; impact-absorbing material housed within the outer casing; and an impact member associated with the unit such that, in use, the initial force of a lateral impact on the unit is received by the impact member and thereafter distributed to the impact-absorbing material.

One or more such lateral impact-absorbing units could be particularly useful as part of a crash barrier arrangement on a motor racing circuit, in which the majority of impacts will be laterally received.

According to a further aspect there is provided a fall arrest unit impact member comprising a body which can be associated with a fall arrest unit of the type comprising an outer casing housing impact-absorbing material such that the impact member receives the force of a fall and distributes it to the impact-absorbing material.

The impact member may comprise a substantially laminar panel, such as a panel formed from foamed plastics material The present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic section of a known impact-absorbing unit; Figure 2 is a diagrammatic section of an impact-absorbing unit according to an embodiment of the present invention; Figure 3 is a perspective view of an impact member forming part of the impact-absorbing unit of Figure 2; Figure 4 is a diagrammatic section of the impact-absorbing unit of Figure 2 shown following an impact; Figure 5 is a diagrammatic section of an impact-absorbing unit according to an alternative embodiment; Figure 6 is a diagrammatic section of an impact-absorbing unit formed according to a further alternative embodiment; Figure 7 is a diagrammatic section of an impact-absorbing unit formed according to a still further alternative embodiment; Figure 8 is a diagrammatic section of a lateral impact-absorbing unit formed according to the present invention; Figure 9 is a diagrammatic side view of an array of lateral impact- absorbing units; Figure 10 is an exploded perspective view illustrating the constituent parts of an outer casing forming part of an impact-absorbing units according to the present invention; Figure 11 is a magnified view of the region of a join between two panels forming part of the outer casing of Figure 10; Figure 12 is a plan view of an impact-absorbing unit according to an embodiment of the invention; Figure 13 is a magnified perspective view of one end of an impact- absorbing unit formed according to the present invention; Figure 14 is a magnified perspective view of one end of an impact- absorbing unit formed according to an alternative embodiment; Figure 15 is a perspective view of an impact surface formed by stacking impact-absorbing units according to the present invention 1 on top of the other; Figure 16 is a perspective view of an impact surface formed from the interconnection of a plurality of impact-absorbing units according to the present invention; Figure 17 is a diagrammatic section showing the interconnection of two fall arrest units; Figure 18 is a diagrammatic section of an impact surface including a protective outer sheath; Figure 19 is a section of a fall arrest unit formed according to an embodiment of the present invention; and Figure 20 is a section of a fall arrest unit according to an alternative embodiment of the present invention.

Referring first to Figure 2 there is shown an impact-absorbing unit according to the present invention generally indicated 10. The unit 10 comprises an outer casing 15 formed from a wear-resistant material, and impact-absorbing material 20 in the form of a loose fill of expanded polystyrene granules housed within the casing 15. The outer casing 15 is formed from woven polypropylene.

The unit 10 further comprises an impact member 25 housed within the casing 15. Referring now also to Figure 3, the impact member 25 comprises a laminar panel of generally parallepiped form. The impact member 25 is arranged within the casing 15 such that it is aligned with an upper wall 16 of the casing 15 and is adjacent to it, so that it lies on top of the impact-absorbing material 20.

Referring now also to Figure 4 the unit 10 is shown in use. The unit 10 is orientated so that the side 16 of the casing 15 faces upwards such that the unit 10 rests on its opposite side 17. Accordingly the side 16 of the casing 15 is presented as the impact surface for receiving a falling object. When an object impacts the side 16 the initial force of the impact is received by the impact member 25. Because the impact member 25 is relatively rigid it is deformed by the impact over its length by a much smaller amount towards the casing side 17 than is the case of the known impact-absorbing unit shown in Figure 1. Furthermore, the deformation of the member 25 over its length distributes the impact force over a greatly extended area of impact-absorbing material 20. The combination of the reinforcing characteristics of the impact member 25 which present a semi-rigid impact surface, and the distribution of the impact force resulting from the deformation of the impact member 25 means that the object impacting the unit results in a compression depth D2 considerably less than the corresponding depth Dl of the known unit 1 shown in Figure 1. Referring now to Figure 5 there is shown an alternative embodiment in which an impact-absorbing unit 110 comprises an outer casing 115 housing impact- absorbing material 120. In this embodiment the impact-absorbing material 120 comprises an array of flexible envelopes 121 filled with air. The envelopes 121 are connected to each other at either end via connector portions 122 to form the array. The array of envelopes is introduced into the outer casing 115 by folding it into place to form an impact-absorbing structure with a sinuous configuration in which the plurality of impact-absorbing envelopes 121 are arranged in stacks.

In this embodiment the impact member 125 is located externally of the casing 115 and is attached by any convenient means such as adhesive, stitching or clips to hold it in place. The working of the unit 110 is the same as that described for the unit 10 of Figure 4.

Referring now to Figure 6 there is shown a unit 210 according to an alternative embodiment. In this embodiment the unit 210 comprises an outer casing 215 which houses impact-absorbing material 220 in the form of a loose fill of compressible granules. In this embodiment the compressible granules 220 are themselves housed within a flexible inner envelope 230. Adjacent either side 216, 217 of the casing 215 is positioned an impact member 225 of the same type shown in Figures 2 to 4 such that the inner envelope 230 is sandwiched between the impact members 225. By containing the compressible granules 220 within an inner envelope 230 this prevents migration of the compressible granules in between the casing sides 216 and the impact members 225 over time, which could reduce the efficiency of the unit. In addition, because there are two impact members 225 along either side of 216, 217 of the unit 210, the unit can be placed with either side 216, 217 as the impact surface.

Referring now to Figure 7 there is shown a unit 310 according to an alternative embodiment. In this embodiment an outer casing 215 houses impact-absorbing material in the form of compressible granules 220. The casing 315 also houses an impact member 325. The impact member 325 comprises a generally tubular structure with an elliptical section. The granules 320 are housed substantially within the hollow section of the impact member 325. Upon experiencing an impact the impact member 325 receives the initial force of the impact which causes it to flex and transfer the impact force to the impact-absorbing material 320 as described in relation to Figure 4. In this embodiment, however, the tubular structure will tend to flatten and the force will be distributed around the member 325 to an even greater area of impact-absorbing material 320.

Referring now to Figure 8 there is shown a lateral impact-absorbing unit generally indicated 410. The unit 410 is similar to the unit 10 shown in Figures 2 and 4, in that it comprises an outer casing 415 housing impact-absorbing material in the form of compressible granules 420 and an impact member 425 arranged to lie along one side 416 of the casing 415. In this embodiment the unit 410 is intended to be suspended or placed against an upwardly extending member such as a wall or crash barrier such that the side 416 is presented as a surface for receiving impacts laterally as opposed to from above. The unit 410 may be provided with means to allow it to be secured in position in this orientation such as straps (not shown). With the unit 410 in position it is suitable for receiving impacts laterally, whereupon the impact-absorbing characteristics of the unit 410 are identical to that described in relation to Figure 4.

Referring now to Figure 9 there is shown three impact-absorbing units 510 formed into a linear array. Each of the units 510 comprises an outer casing 515 housing impact-absorbing material (not shown). A single elongated impact member 525 is provided and spans across the units 510, serving to join them together.

Referring now to Figure 10 the construction of an outer casing 615 suitable for forming a fall arrest unit according to the present invention is shown. The casing 615 is formed from two major panels 630, 635 and two rectangular end panels 640, 645. The casing 615 may be formed by joining the panels 630, 635, 640, 645 to form an open-sided enclosure allowing insertion of one or more fluid-containment envelopes before the opening is closed along the remaining edge between the panels 630 and 635. Alternatively, the panels 630, 635, 640 may be first be joined to form an open-ended sack before impact-absorbing material is inserted before the rectangular end panel 645 is used to close the casing 615.

Referring now to Figure 11 there is shown a magnified view of the region of the join between two panels 630, 640. Where the edges of the panels 630, 640 meet they are pressed together to form two lips 631, 641 and stitched over the join; a chain overlock stitch 647 is preferred as this type of stitching serves to secure earlier stitches which results in a strong join. In this way a rigid upstanding rib 637 is formed at the periphery of the panels 630, 640 and likewise along the longitudinal edges of the panels 630, 635 which helps to maintain the shape of the units. If the stitches are close together the result is a substantially continuous sheath which helps to protect the most vulnerable part of the fall arrest unit.

Referring now to Figure 12 there is shown the top surface 632 of the fall arrest unit 610, which comprises the sub-panel 632 of the panel 630. The surface 632 has three lateral interconnection modules 660 mutually spaces along its length, and a longitudinal interconnection module 665 at either end thereof. Referring now also to Figure 13, the lateral interconnection modules 660 comprise a lateral strap 670 secured at either end by stitching 671 and having a male 675 and female 680 portion of a clasp fastener at either end. The strap 670 is loose between the stitching 671 to form a handle for manipulating the unit 610. The longitudinal interconnection module 665 comprises a female or male (in this embodiment a female) portion of a clasp fastener. In some embodiments at each end of the unit 610 both the male and female clasp fastener portion is provided so that the orientation of units 610 with respect to each other is not important for interconnection purposes.

Referring to Figure 14 there is shown an alternative arrangement of a lateral interconnection module 760. The strap 770 is secured at either of its ends by stitching along or adjacent to the respective longitudinal edges of the panels 730, 735. Male and female connectors 775, 780 are in this embodiment threaded onto the strap using respective aperture eyelets 776, 782 which allows movement of the connectors along the strap to effect adjustment of their position.

Referring now to Figure 15 there is shown a protective impact surface formed from the interconnection of a plurality of units 810. In this embodiment the interconnection means comprise longitudinal and lateral hook and loop fastener panels 890, 895 stitched onto adjacent panels of the outer casing 815 and allowing the units 810 to be placed in a closely adjacent relationship to form a substantially continuous impact surface. Once the units 810 are assembled an impact member 825 is laid onto their upper surfaces.

Referring now to Figure 16, units 910 are shown provided with hook and loop fastener panels 996 on adjacent upper and lower surfaces of the units 910. The panels 996 allow the unit 901 to be securely stacked one on top of the other. An impact member 925 is then secured along adjacent sides of the units 910.

A combination of the panels 996 shown in Figure 16 and the panels 890, 895 shown in Figure 15 could be used to produce a multi-layered extended impact surface from a plurality of fall arrest units.

Referring now to Figure 17 there is shown two impact absorbing units 1010 each comprising an outer wear-resistant casing 1015 and impact absorbing material in the form of a loose fill of expanding polystyrene granules 1020. Each unit 1010 includes an impact member 1025 in the form of a 20mm thick sheet of extruded polyethylene which lies along the inner face of an upper impact surface formed by a wall 1011 of the units 1010.

The units are shown placed in a juxtaposed relationship with the impact members 1025 being co-linear. In order to secure the units 1010 together, corresponding respective upper and lower edges of the units include one half of a zip arrangement 1016. The zip arrangements 1016 allow the units to be joined together along the adjacent edges of their corresponding upper 1011 and lower 1012 walls.

In order to protect the zip arrangements and provide a smooth impact surface, flaps 1017 are provided. One end of the flaps 1017 is stitched to the outer casing 1015 on either the upper or lower surface 1011, 1012 of a unit and then include one part 1018 of a hook and eye arrangement at their other end for engagement with the other part 1019 of the hook and eye arrangement present on the other of the upper or lower surface 1011, 1012. The flap arrangements on the upper and lower surfaces are therefore mirror images of each other so that the units each have one flap 1017 stitched thereto which spans across to the other unit in use.

Referring now to Figure 18 there is shown three impact absorbing units 1110 each comprising an outer wear-resistant casing 1115 and an inner envelope 1130 housing compressible granular impact-absorbing material 1120. The units 1110 are connected together in a linear array to form an impact- absorbing structure in the same way as that shown in Figure 17 with a zip arrangement 1116 covered by a flap 1117. An impact member 1125 in the form of a foam pad is laid across the top surfaces 1111 of the units 1110. An outer sheath 1105 is wrapped around the impact-absorbing structure with the impact member 1125 in place. The sheath 1105 is formed from PVC (polyvinylchloride) and is resistant to damage resulting from impacts. The sheath 1105 not only protects the impact structure but also serves to hold the impact member 1125 in position.

Referring now to Figure 19 there is shown a fall arrest unit 1210 comprising an outer wear-resistant casing 1215 housing an inner envelope 1230 filled with a loose filled granular impact absorbing material 1220. The unit 1210 is shown resting on the floor 1297 of a building construction site (such as the interior of a house under construction). An impact surface 1206 of the unit is oriented to face upwards so as to present a surface upon which falling objects are received. The surface 1206 includes a pocket 1207 within which a laminar impact member 1225 is received. In the event that the envelope 1230 ruptures and material 1220 is released into the casing 1215 the member 1225 remains adjacent the surface 1206 because it is retained in position by the pocket 1207; furthermore the member 1225 is isolated from the material 1220 by the pocket 1207. Therefore even during transportation or use involving impacts which moves the material 1220, the material does not displace the member 1225 away from the surface 1206 by migrating between them. In Figure 20 a fall arrest unit 1310 according to an alternative embodiment is shown. The unit 1310 comprises an outer wear-resistant casing 1315 directly housing particulate cushioning material 1320. An impact member 1325 is retained adjacent the interior surface of an impact surface 1306 by three internal straps 1308 which prevent the member 1325 from moving away from the impact surface 1306.