The invention has been developed primarily for use as an impact- absorbing crash barrier for vehicles and will therefore be described in this context. It is to be understood, however, that the invention may have other uses.

BACKGROUND OF THE INVENTION Crash barriers are used in motor sport events to minimise harm to drivers and damage to motor vehicles as well as to protect structures on the raceway from damage. A general disadvantage of some known types of crash barriers is that they deform irreversibly upon impact and consequently cannot be reused.

Tyre barriers are widely used on raceways and these typically comprise stacks of used rubber tyres that have been secured to one another.

Although tyre barriers overcome the above-mentioned disadvantage in that they do not deform irreversibly upon impact, they have a disadvantage in that they may lack uniformity in their ability to absorb an impact. This is because some tyres are likely to be more worn than others, some tyres may be retreads, some may be steel-belted, and as a consequence each tyre will have a different ability to absorb the kinetic energy of a colliding vehicle.

Moreover, the properties of tyre barriers continue to change whilst exposed to the elements, the elements being UV light from the sun and wet weather.

Consequently, a first tyre barrier may thus have significantly different kinetic energy absorbing properties to a second tyre barrier on the same raceway.

OBJECT OF THE INVENTION It is therefore an object of the present invention to provide an impact-absorbing cell that minimises or overcomes at least one of the disadvantages mentioned above, or provides the public with a useful or commercial choice.

SUMMARY OF THE INVENTION According to the present invention there is provided an impact-

absorbing cell having: a flexible housing having at least one passage enabling air to pass into and out of the housing; and flexible resilient beads within the housing, wherein when a body collides with the cell, the housing and the beads compress and air is expelled from the housing, and the cell may revert to the shape that it had prior to the collision occurring.

DETAILED DESCRIPTION OF THE INVENTION The beads may be of any suitable composition, shape and size.

The beads may be, for instance, spheres, rectangular prisms, triangular prisms or of irregular shape. The beads may be hollow or may not be hollow.

Preferably, the beads are substantially spherical. The beads may comprise, for example, beads of polypropylene, polystyrene, polyethylene, polyurethane, sponge rubber (eg. cellular urethane foam or silicone foam) or polyvinyl. Preferably, the beads cannot absorb or retain water.

The housing may contain two or more types of beads of differing density. For example, the housing may contain polypropylene beads and beads of sponge rubber mixed according to a predetermined ratio. Any suitable ratio may be used. In this way, the density of the cell may be varied in accordance with the mass and velocity of the body that is likely to collide with the cell, wherein higher density cells are generally used for bodies of greater mass and/or velocity.

The housing may comprise any suitable flexible material or materials and preferably the housing is tear-resistant. The housing may comprise, for instance, PVC polyester weave fabric or canvas. Preferably, the housing is water repellant.

The cell may be of any suitable geometric shape and size. The cell may, for instance, have a cylindrical shape or the shape of a rectangular prism, in which case, the housing may have a pair of opposed end walls and at least one interconnecting sidewall. Preferably, the cell is free-standing when resting on one of its end walls. However, it is to be appreciated that the cell may be equally functional when resting on its sidewall.

The number, the size and the spacing of passages in the housing

end walls and sidewall may vary in order to determine the rate at which air may be expelled from the housing, so that the cell may cushion the body and so that the cell will not rupture when a body collides with it. A plurality of passages may be located at spaced intervals in the end walls and the sidewall. Preferably, each of the passages is less than about 4mm in diameter. More preferably, the passages located in or adjacent to the end walls are at more closely spaced intervals than passages located in a central region of the sidewall. The passages in the central region of the sidewall may be spaced at intervals of about 50 to 60mm, whereas the passages in or adjacent to the end walls may spaced at intervals of about 5mm. The spacing of adjacent passages may gradually decrease when moving from the central region towards the end walls.

The cell preferably has at least one salable opening that may be opened when filling the housing with the beads. The cell may have any suitable type of salable opening known to persons skilled in the art (eg. zipper, a plug). Preferably, the cell has a closure such as a plug for sealing an opening of the housing. The opening is preferably in one of the end walls.

Depending on the size of the plug, the plug may have at least one passage enabling air to pass into and out of the housing. The plug may comprise, for instance, plastics material or rubber.

The size, shape and composition of the cell will depend on the amount of kinetic energy that the cell is to absorb.

A cell having a thick housing tightly packed with beads is more likely to revert to its pre-collision shape compared with a cell having a thin housing loosely packed with beads. The beads may be packed into the housing using any suitable mans (e. g. blowing the beads into the housing).

If necessary, the cell may have structural members for helping the cell maintain its shape. Any suitable types of structural members may be used. Structural members may be of importance particularly if the cell is of large size. The structural members may extend between opposing or adjacent walls of the housing. The structural members may comprise, for instance, eyelets in select walls of the housing with ties (eg. ropes) extending between the eyelets. Other types of structural members may attach one cell

to another.

The cell may have at least one partition extending within the housing for maintaining the shape of the cell and dividing the interior of the housing into more than one compartment. The partition may have an aperture enabling the beads to pass therethrough when filling the housing with the beads.

In some applications a plurality of cells may be used together so as to form a larger crash barrier.

According to another aspect of the invention, there is provided an impact-absorbing crash barrier comprising a plurality of cells, wherein each cell has: a flexible housing having at least one passage enabling air to pass into and out of the housing; and flexible resilient beads within the housing, wherein when a body collides with the cell, the housing and the beads compress and air is expelled from the housing, and the cell may revert to the shape that it had prior to the collision occurring.

The cells may be stacked on top of one another much like bricks in a brick wall or positioned in a side by side relationship. Preferably, each cell of the crash barrier is of the same geometric shape and has identical properties. However, the cells need not be of the same geometric shape and need not have identical properties.

Preferably, the cells of the crash barrier are securable together as a group. This may be achieved using any suitable means known to persons skilled in the art. The cells may be secured to one another or contained within a further housing of sorts. For instance, the cells may be held together as a group with a flexible membrane, such as rubber or conveyor-type material (eg. PVC woven ply material). The cells may also or alternatively be grouped between sidewalls comprising polycarbonate sheeting.

Preferably, the cells are secured together in such a way that individual (damaged) cells may be removed from the crash barrier and replaced with other (undamaged) cells.

The size, shape and composition of each cell as well as the

number of cells used in the crash barrier will depend on the amount of kinetic energy that the crash barrier is to absorb.

According to yet another aspect of the invention, there is provided an impact-absorbing cell having: a flexible housing having at least one passage enabling air to pass into and out of the housing; and a flexible resilient fill within the housing, said fill being of substantially uniform density, wherein when a body collides with the cell, the housing and the fill compress and air is expelled from the housing, and the cell may revert to the shape that it had prior to the collision occurring.

The fill may comprise any suitable particulate material or materials.

For instance, the fill may comprise rubber crumb, spherical, globular, cubic or triangular beads (i. e. small fragments of any shape). Preferably, the fill comprises spherical beads as described earlier in the specification.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cut-away perspective view of an impact-absorbing cell according to an embodiment of the invention; Figure 2 shows top plan views of various impact-absorbing cells according to other embodiments of the invention; Figure 3 shows top plan views of various impact-absorbing crash barriers according to embodiments of the invention; Figure 4 shows a partial top plan view of an impact-absorbing crash barrier according to an embodiment of the invention; and Figure 5 shows a part detailed perspective view of the impact- absorbing crash barrier of Figure 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In all of the figures like reference numerals refer to like parts.

Referring first to Figure 1, there is shown an impact-absorbing cell 1 having a flexible housing 2 and flexible resilient beads 3 tightly packed into the housing 2. The housing 2 has a plurality of passages 9 (only some of which have been labeled) that enable air to pass into and out of the housing 2.

The housing 2 contains a mixture of polypropylene beads 4 (represented in black) and beads of sponge rubber 8 (represented in white).

These beads 4,8 have differing densities. Spaces between adjacent beads 4,8 are occupied by air.

The housing 2 is cylindrical in shape, it has an upper end wall 6, a lower end wall 7 and an interconnecting sidewall 40. The housing 2 is made of PVC panama polyester weave fabric.

An opening 10 in end wall 6 is salable with a rubber plug 5. The plug 5 may be removed when either filling the housing 2 with beads 3 or when removing the beads 3 from the housing 2.

The number, the size and the spacing of passages 9 in the housing 2 end walls 6,7 and sidewall 40 may vary in order to control the rate at which air may be expelled from the housing 2. Each passage 9 of the housing 2 has a diameter of about 4mm. Although not clearly shown in Figure 1, the spacing between adjacent passages 9 gradually decreases when moving from a central region of the sidewall 40 towards end walls 6 and 7. The passages 9 at the central region of the housing 2 are spaced at about 50 to 60mm, whereas the passages 9 at end walls 6 and 7 are spaced at about 5mm.

In use, when a body such as a vehicle collides with the cell 1, the housing 2 together with the beads 4,8 compress and air from between the beads 4,8 is expelled from the housing 2 through passages 9. In this way, the cell 1 cushions the colliding vehicle. After the collision, the housing 2 and the beads 4,8 revert to substantially the shape that they had prior to the collision occurring and air is drawn back into the housing 2 by way of the passages 9. The thickness of the housing 2 and the fact that the beads 3 are tightly packed within the housing 2 are factors that assist the cell 1 in reverting to the shape that it had prior to the collision occurring.

Should the housing 2 have been damaged in the collision, the plug 5 is removed and the beads 3 are extracted and recycled.

The size, shape and composition of the cell will depend on the amount of kinetic energy that the cell is to absorb. The size, the number and the spacing of passages in the housing may be varied in order to control the

cushioning effect of the cell.

The density of the cell may be varied in accordance with the mass and velocity of the vehicle likely to collide with the cell. A cell of higher density may be used for vehicles of greater mass and/or velocity. The density of the cell may be varied by changing the ratio of polypropylene beads to beads of foam rubber.

Figure 2 shows other possible embodiments of the impact- absorbing cell. The cell may be in the shape of a square prism 15, a hexagonal prism 16 or a rectangular prism 17,50.

Cell 50 has a plurality of partitions 51 (only some of which have been labeled) that define a plurality of compartments 52 (only some of which have been labeled) within a housing 55 of the cell 50. The partitions 51 assist the cell 50 in maintaining its shape. Each partition 51 has an aperture 50 (only some of which have been labeled). A plug 54 is used to seal an opening in an end wall of the housing 55. In order to pack the housing 55 with beads, the plug 54 is removed and the beads are blown into the housing 55.

The beads flow through apertures 53 and fill each of the compartments 52.

Figures 3-5 show how rows of cells having the same geometric shape may be used together as larger impact-absorbing crash barriers 21, 22,23, 24,35. The cells are shown grouped together within sidewalls of sorts. However, larger crash barriers can equally comprise cells of different geometric shapes and the cells can be grouped together in other ways.

Figure 4 shows cells 27 contained within four sidewalls 25,26.

The two longer sidewalls 25 comprise conveyor-type material and each of the adjacent shorter sidewalls 26 comprises polycarbonate sheeting. Sidewalls 25 and 26 are connected to one another with corner brackets 28 and fasteners 29.

Figure 5 shows that the crash barrier 35 also has bracing straps 34 that extend between parallel sidewalls 25 and between adjacent cells 27.

Bracing straps 34 are connected to sidewalls 25 with bolts 33.

It is to be understood that the cells 27 may be grouped together in any suitable way. For instance, the cells 27 may alternatively be grouped together using conveyor-type material alone.

The size and shape of each cell, the choice of housing and beads, the number of cells, the way in which the cells are grouped, and the choice of sidewalls for grouping the cells will depend on the amount of kinetic energy that the crash barrier is to absorb.

The crash barrier may comprise cells placed on their sides or on their ends. That is, the cells may be stacked on top of one another like bricks in a brick wall, or positioned in a side by side relationship.

In this way, the kinetic energy absorbing capabilities of the cells and of the larger crash barrier may be uniform and predictable, and cells of the barrier that survive the impact may revert to the shape that they had prior to the collision occurring. Any cells of the crash barrier damaged by a vehicle may be readily removed and replaced with new cells having the same properties as the intact cells of the crash barrier.