Shock absorption bumper for an automotive vehicle
This is a continuation of application Ser. No. 699,009, filed July 2, 1976 and now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention concerns an energy-absorption device, principally for vehicles. 
     It is known that when a light vehicle comes into collision with an obstacle, the shock imposed on the occupants is due to the rapid deceleration of the vehicle. This deceleration is accompanied by a deformation of the car, and a deformation of the obstacle, corresponding to the absorption of the kinetic energy of the car. The deformations have the advantage of reducing the violence of the shock by diminishing the maximum value of the deceleration, but the deformations of the car are dangerous for the passengers. It is desirable, therefore, to obtain deformation of the obstacle. 
     One of the most dangerous obstacles is the heavy goods vehicle, for it is on the road itself and has a large mass. For this purpose, it is known for the rear of heavy goods vehicles to be fitted with a bumper designed to stop vehicles becoming embedded underneath them, for the rear is the part of them most exposed to being struck by cars. This bumper must be able, in case of collision, to deform sufficiently to absorb the maximum energy. However it must be fixed very solidly and be sufficiently resistant to collisions in order to tolerate large impacts in case other parts of the two vehicles come into contact, for example the windscreen area of the car with the rear of the goods vehicle. 
     SUMMARY OF THE INVENTION 
     The present invention has the aim of providing an energy absorption device more resistant than the traditional rear bumpers, but capable of absorbing more energy whatever may be the relative directions of the trajectories of the vehicles before the collision. 
     An energy absorption device according to the invention, principally intended to be mounted as a bumper on a heavy goods vehicle is characterised in that it comprises a core constituted by a plurality of superimposed corrugated bands being configured with arserte apices, two adjacent bands being arranged in such a way that the arcuate apices of the corrugations butt against each other, so that a collision between two vehicles situated one on each side of the device is absorbed by a concurrent flattening of the arcuate apices of the corrugations. 
     According to an additional characteristic of the invention, the corrugated bands are stacked in such a way that two adjacent bands have their corrugations running at right angles. 
     According to a variant of the invention, the corrugated bands are stacked in such a way that two adjacent bands have their corrugations running at any angle between 0° and 90°. 
     According to an additional variant of the invention the bands all have corrugations at the same spacing, and they are stacked in such a way that two adjacent bands have their corrugations parallel, and defining a series of long parallel cavities. 
     According to an additional characteristic of the invention, all the bands are in the same material and are of the same thickness with corrugations of the same shape. 
     According to a variant of the invention, the bands are chosen so that their rigidity differs and increases from the external face to the internal face of the core. 
     According to an additional characteristic of the invention, the bands are assembled to each other by screwing or riveting. 
     According to a variant of the invention, the bands are assembled to each other by welding or sticking. 
     According to an additional characteristic of the invention, the internal face of the core is fixed to a rigid flat support capable of little deformation. 
     According to an additional characteristic of the invention, the core of the device is laterally inset against a rigid beam, such as an &#34;I&#34; beam, so that its internal face rests against the web of the &#34;I&#34;, while the whole is entirely enclosed in a light deformable body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The attached drawings, given by way of non-limiting example, will allow the characteristics of the invention to be better understood. 
     FIG. 1 is a part view in perspective of the energy-absorption device. 
     FIG. 2 is a part view in perspective of a corrugated band. 
     FIG. 3 is a diagram illustrating the operation. 
     FIG. 4 is a perspective view of the core according to the invention. 
     FIG. 5 is a perspective view of a van fitted with an energy absorption device according to the invention. 
     FIG. 6 is an end view of a tier of bands of increasing thickness from the periphery to the core of the tier. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The van 1 shown in FIG. 5 carries a rear bumper constituted by an energy-absorption device 2 according to the invention. This device 2 presents the external appearance of a parallelepiped of which the greatest dimension lies transversely to the central longitudinal plane of the vehicle. 
     The devide 2 as shown in FIG. 1, comprises a support 3, a core 4 and an outer body 5. 
     The support 3 is a beam such as an &#34;I&#34; beam, arranged with its web 6 vertical, and fixed very solidly to the chassis of the van 1. This support 3 is a rigid part, therefore is not intended to undergo deformation in case of a collision. 
     The core 4 of which the internal part is inset into the support 3, is constituted by a plurality of superimposed corrugated bands 7 each corrugation being configured with arcuate rounded apices stacked in such a way that the arcuate apices of the corrugations of two adjacent bands abut and may be oriented with respect to each other at right angles. The bands 7 are attached to one another by sticking or welding to thereby form a stacked tier. They may equally be riveted or screwed. These bands may in addition be made from rigid or semi-rigid material such as steel, aluminium, plastic material etc. 
     The material may likewise vary from one band to another, and bands may be arranged with their thickness increasing from the external face to the internal face of the core. FIG. 6 shows a tier where the bands are arranged with their thickness increasing from the faces to the center of the core. 
     The operation is as follows: 
     When a shock occurs at the rear of the van, as the result of a collision, for example by a car striking the van, the device 2 absorbs energy by deforming between the two vehicles like a spring. However, contrary to the latter, it does not store or restitute this energy after compression; its deformations are permanent. In addition its deformations may be localized or different if the structure of the striking vehicle is not of homogeneous stiffness. 
     The body 5 constitutes only a simple deformable exterior protection. It is, for example, made from metal or plastics. 
     There is shown in FIG. 2 one of the bands 7 of the core 4 of FIG. 1 after a shock. The areas of contact 8 with the adjacent band are limited by circles and result from a partial flattening of the joined arcuate apices of the corrugations. Throughout the duration of the shock the diameter of the circles increases to thereby be deformable under compressive loading. 
     The diagram of FIG. 3 represents for three different structures as a function of time, the variations in thickness of the core during a shock. The curves 9, 10 and 11 represent the crushing of the core in relation to time for a given shock, that is to say for the same mass moving at the same speed. In all cases the thickness varies between the values E o  and E f , the degree of crushing being E o  -E f , but the curves are at different slopes. This slope characterizes the &#34;shock absorbing ability&#34; of the device. The shock-absorbing ability may be chosen by varying: 
     the nature of the materials used for the manufacture of the core, 
     the thickness of these materials, 
     the form and the dimensions of the corrugations, 
     the number of alternated bands. 
     Likewise materials of different rigidity may be used, or bands of different thicknesses arranged in the same core. There will then be obtained a composite curve 12 with angular points corresponding to the successive deformations of the different bands. 
     According to a variant of the invention, there is shown in FIG. 4 a core constituted by the juxtaposition of corrugated bands 13 of which the corrugations are at the same spacing. Their arrangement is such that the projecting parts of the corrugations of two adjacent bands butt against one another, thus delimiting between these two bands a series of elongated parallel cavities, giving the core a honeycomb structure. 
     In this case, when a shock occurs, the areas of contact are no longer circular surfaces, but rectangular surfaces 14 as shown in FIG. 5. During the shock, the rectangles are of constant length and increasing width (FIG. 5). 
     The principal advantage of the energy-absorption device according to the invention is to be resistant while ahsorbing a large amount of energy whenever shock occurs, whatever are the relative directions of the trajectories of the vehicles before the shock. 
     The scope of the invention will not be exceeded by using a core of which the bands have their corrugations set at any angle between 0° and 90°. 
     Having described my invention, it will be apparent to those skilled in the art to vary the design and features of the invention without departing from the scope of the invention or the claims therefor.