Improved composite crush can

Abstract

The present invention relates to a composite crush can 100 for a vehicle (figure 11), an energy absorption system for a vehicle, and a vehicle, both comprising the composite crush can. The composite crush can comprises: a first end 102 and a second end 104, each disposed on a longitudinal axis 106; and an enclosing wall 108 extending between the first and second ends and comprising a continuous surface between the two ends; wherein the enclosing wall has a first region 126 and two or more second regions 128a-e, 128c’-e’, wherein the two or more second regions extend longitudinally at least part way between the first and second ends and have an increased thickness compared to the first region. The enclosing wall may taper inwardly from the first end towards the second end, and may comprise a top wall 110, bottom wall 112 and two side walls 108. The second regions may comprise ribs and may be located on an external surface and / or an internal surface of the enclosing wall (figures 6, 7). The second end of the crush can may be attached to an internal surface of a bumper beam (1300, figure 10) of the vehicle.

Description

TECHNICAL FIELD The present disclosure relates to a composite crush can. Aspects of the invention relate to a composite crush can for a vehicle, an energy absorption system for a vehicle, comprising a composite crush can and a vehicle comprising a composite crush can according to embodiments of the invention. BACKGROUND It is known to provide energy absorption systems for vehicles to absorb energy arising from a crash event. Such energy absorption systems typically comprise two spaced apart crush cans secured at one end to part of a vehicle body, and at the other end to a bumper beam, typically formed of metal. The crush can acts to absorb energy from a crash event by deforming, crumpling or even being significantly crushed. The crush can therefore serves to protect the vehicle occupants by absorbing a proportion of the crash energy in place of it being transferred more substantially to the occupants, as well as protecting critical vehicle components that may otherwise become damaged if they are positioned in the impact region, by providing a crumple or crush zone around these components. More recently, crush cans have been formed of a composite material instead of the traditional metal construction, with the aim of reducing the weight of the crush can to assist in reducing the overall weight of a vehicle and therefore in turn, reducing fuel or energy consumption of that vehicle. Composite crush cans may demonstrate improved energy absorption as compared to traditional metal cans, depending on certain factors such as the material used for the crush can. However, composite crush cans are known to shatter in response to absorbing the high amount of energy arising from an impact event which is undesirable. It is also to provide one or more comers in the wall of the crush can to improve their energy absorption capabilities. However, adding more corners may increase complexity of the manufacturing process. For example, the addition of more corners increases friction during release of the can from the mould at the end of the moulding process, making ejection of the can from the mould more challenging. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a composite crush can, an energy absorbing system comprising the composite crush can and a vehicle comprising the composite crush can as claimed in the appended claims. According to an aspect of the present invention there is provided a composite crush can for a vehicle, the composite crush can comprising: a first end and a second end, each disposed on a longitudinal axis of the composite crush can; and an enclosing wall extending between the first end and the second end, the enclosing wall comprising a continuous surface between the first and the second end; wherein the enclosing wall comprises a first region and two or more second regions, wherein the two or more second regions extend longitudinally at least part way between the first end and the second end and have an increased resistance to crushing in response to an impact force, as compared to the first region. Providing two or more second regions having an increased resistance to crushing in response to an impact force, as compared to the first region, enables the crush can to be strengthened against impact forces as compared to a can which lacks the two or more second regions having an increased resistance to crushing. According to another aspect of the present invention there is provided a composite crush can for a vehicle, the composite crush can comprising: a first end and a second end, each disposed on a longitudinal axis of the composite crush can; and an enclosing wall extending between the first end and the second end, the enclosing wall comprising a continuous surface between the first and the second end; wherein the enclosing wall comprises a first region and two or more second regions, wherein the two or more second regions extend longitudinally at least partway between the first end and the second end and have an increased thickness as compared to the first region. Providing an enclosing wall having two or more second regions which have an increased thickness as compared to a first region of the composite crush can enables the crush can to be strengthened against impact forces as the increased thickness of the two or more second regions arises from an increase in the amount of composite material in these second regions, and increasing the amount of composite material in these localised regions of the crush can provides more composite material for absorbing impact energy. Using regions of increased thickness to strengthen the can increases the degree of design freedom as compared to designing a crush can which incorporates corners as a strengthening feature, because the regions of increased thickness can be located at any point along the enclosing wall of the composite crush can and can be located on the interior surface or exterior surface of the enclosing wall independently, in contrast to providing a corner or curvature in the enclosing wall that would necessarily affect the shape of the enclosing wall on both the interior and exterior surfaces. The additional design freedom afforded by providing regions of increased thickness on the enclosing wall enables the creation of an improved crush performance for the composite crush can and can allow for accommodation of any other vehicle or vehicle frame components that may be mounted adjacent the crush can. Using regions of increased thickness to strengthen the enclosing wall of the composite crush can has an additional advantage of not requiring the crush can to be limited to a particular shape, as may be the case when incorporating corners or curvatures into the enclosing wall to strengthen it. Using regions of increased thickness to strengthen the enclosing wall of the composite crush can rather than incorporating corners into the enclosing wall may also be easier to manufacture, as ejecting a moulded crush can out of a mould is easier if the crush can lacks corners or as the presence of corners can increase friction during release of the can from the mould at the end of the moulding process. Optionally, a cross section of the enclosing wall may be configured to taper inwardly from the first end towards the second end. By tapering the cross section of the can from a larger cross section at the first end of the crush can which may be configured to attach to a part of the vehicle frame towards a smaller cross section at the second end of the crush can which may be configured to attach to or abut a bumper beam, an increasing amount of composite material is available for absorbing impact energy during the crushing process. Providing a lesser amount of composite material at the second end of the crush can provides less resistance to crushing as compared to the crush resistance at the first end which assists in initiating crushing of the crush can following an impact event. Optionally, the enclosing wall may comprise a top wall, a bottom wall and first and second side walls. Forming the enclosing wall to comprise a top wall, a bottom wall, a first side wall and second side wall provides multiple distinct surfaces on which one or more regions of increased thickness can be formed. The corners between the top wall, side walls and bottom wall further increase the strength of the crush can. Optionally, one or more of the two or more second regions may be located on the top wall and / or the bottom wall. Locating the two or more second regions on the top wall and / or the bottom wall provides additional strength to the composite crush can along these walls. Being able to locate the two or more second regions on either or both of the top wall and bottom wall increases the design freedom available when designing the improved crush performance for the composite crush can. Optionally, one or more of the two or more second regions may be located on the first side wall and / or second side wall. Locating the two or more second regions on the first side wall and / or the second side wall provides additional strength to the composite crush can along these walls. Being able to locate the two or more second regions on either or both of the first side wall and second side wall increases the design freedom available when designing the improved crush performance for the composite crush can. Optionally, the one of the two or more second regions on the top wall is located directly opposite another one of the two or more second regions on the bottom wall. Locating one or the two or more second regions on the top wall directly opposite another one of the two or more second regions on the bottom wall provides a symmetrical arrangement of regions of increased thickness in the enclosing wall of the composite crush can. Optionally, the one of the two or more second regions on the first side wall may be located directly opposite another one of the two or more second regions on the second side wall. Locating one or the two or more second regions on the first side wall directly opposite another one of the two or more second regions on the second side wall provides a symmetrical arrangement of regions of increased thickness in the enclosing wall of the composite crush can. Optionally, the increased thickness of the two or more second regions may extend from an external surface of the enclosing wall and / or from an internal surface of the enclosing wall. Providing regions of increased thickness extending from either or both of the external surface and internal surface of the enclosing wall increases the design freedom available when designing the improved crush performance for the crush can. Optionally, the thickness of one or both of the two or more second regions in a first direction may change along the longitudinal axis of the composite crush can. Varying the thickness of one or both of the two or more second regions in a first direction as the two or more second regions extend along the longitudinal axis of the crush can allows for further customisation of the crush performance of the can by providing different thicknesses of enclosing wall at various points along the longitudinal axis of the crush can. For example, the first direction may be a height direction, i.e. in the y-direction. The thickness of the two or more second regions may be greater towards the first end of the composite crush can, closest to the vehicle frame, as compared to towards the second end of the crush can, closest to the bumper beam. With such an arrangement, the increasing thickness of the two or more second regions approaching the first end of the can provides an increasing amount of composite material available for absorbing crush energy as the can is crushed from the second end towards the first end. In an alternative, non-limiting arrangement, the thickness of one or both of the two or more second regions may vary in the first direction so as to alternate between regions of greater thickness in the first direction and regions of lesser thickness in the first direction, at various points along the longitudinal axis of the crush can. The ability to be able to provide regions of increased thickness at any location on the enclosing wall, and / or being able to vary the thickness of those regions of increased thickness at any location on the enclosing wall provides significant design freedom when customising the composite crush can performance. Optionally, the thickness of one or both of the two or more second regions in a second direction may change along the longitudinal axis of the composite crush can. Varying the thickness of one or both of the two or more second regions in a second direction as the two or more second regions extend along the longitudinal axis of the crush can allows for further customisation of the crush performance of the can by providing different thicknesses of enclosing wall at various points along the longitudinal axis of the crush can. For example, the second direction may be a width direction, i.e. in the x-direction. The thickness of the two or more second regions may be greater towards the first end of the composite crush can, closest to the vehicle frame, as compared to towards the second end of the crush can, closest to the bumper beam. With such an arrangement, the increasing thickness of the two or more second regions approaching the first end of the can provides an increasing amount of composite material available for absorbing crush energy as the can is crushed from the second end towards the first end, and conversely, a lesser amount of material at the second end of the crush can offers lesser resistance to impact energy which can assist with initiating the process of crushing the crush can following an impact event. In an alternative, non-limiting arrangement, the thickness of one or both of the two or more second regions may vary in the second direction so as to alternate between regions of greater thickness in the second direction and regions of lesser thickness in the second direction, at various points along the longitudinal axis of the crush can. The ability to be able to provide regions of increased thickness at any location on the enclosing wall, and / or being able to vary the thickness of those regions of increased thickness at any location on the enclosing wall provides significant design freedom when customising the composite crush can performance. Optionally, each, or one or more of the two or more second regions may comprise a rib. Forming one or more of the two or more second regions as a rib provides regions of increased thickness in a compact, slender elongate form which does not take up substantial space on the enclosing wall. This offers scope to add further second regions of increased thickness, optionally in the form of ribs, to the enclosing wall to increase its strength and resistance to impact energy. Optionally, each or one or more of the two or more second regions may comprise a radial shape and / or may comprise one or more vertices. Forming each of the two or more second regions in a radial shape increases ease of the manufacturing process as a radial shape is relatively straightforward to create in a mould and allows for relatively easy release of the moulded composite crush can from the mould as the radial shape creates less friction than a corresponding shape having a number of vertices. In one or more embodiments, each of the two or more second regions may comprise a different shape. For example, one or more of the two or more second regions may comprise a radial shape and one or more of the two or more second regions may comprise a different shape, such as a shape comprising one or more vertices. Providing some or each of the two or more second regions as a different shape increases the design freedom available when designing the improved crush performance requirements for the crush can. Optionally, one or more of the two or more second regions may be integrally formed with respect to the enclosing wall. Alternatively or additionally, one or more of the two or more second regions may be fixed to the enclosing wall. Integrally forming one or more of the two or more second regions improves the ease and efficiency of the manufacturing process as the two or more second regions are formed simultaneously with the enclosing wall during the moulding process. Fixing one or more of the two or more second regions to the enclosing wall can improve design flexibility by enabling customisation of the enclosing wall of the crush can after the crush can has been moulded by allowing regions of increased thickness to be added retrospectively to the enclosing wall. Optionally, the composite crush can may comprise sheet moulding compound (SMC), optionally glass fibre sheet moulding compound and / or carbon fibre sheet moulding compound. Sheet moulding compound (SMC) is relatively low cost as compared to other composites and is easy to handle during manufacturing, thus reducing manufacturing costs and improving ease of manufacturing. The structure of SMC also allows “predictable” shattering of the can after impact, because the fibres within the resin are less randomly distributed as compared to some other composite materials. Optionally, the first end may be configured to attach to a part of the vehicle, such as the vehicle frame. Optionally, the first end may comprise a flange for attaching the composite crush can to the vehicle frame. The first end may be configured to attach to a part of the vehicle, such as the vehicle frame. Optionally, the first end may comprise a flange for attaching the composite crush can to the vehicle frame. Optionally, one of the two or more second regions on the top wall may be located indirectly opposite another one of the two or more second regions on the bottom wall. Locating one of the two or more second regions on the top wall indirectly opposite to another one of the two or more second regions on the bottom wall increases the design freedom available when designing a composite crush can to meet specific crush performance requirements, and / or may allow accommodation of one or more adjacent vehicle components or structures adjacent to the crush can. Optionally, one of the two or more second regions on the first side wall may be located indirectly opposite another one of the two or more second regions on the second side wall. Locating one of the two or more second regions on the first side wall indirectly opposite to another one of the two or more second regions on the second side wall increases the design freedom available when designing a composite crush can to meet specific crush performance requirements, and / or may allow accommodation of one or more adjacent vehicle components or structures adjacent to the crush can. According to another aspect of the present invention there is provided an energy absorption system for a vehicle, comprising a composite crush can according to an aspect of the present invention. According to another aspect of the present invention, there is provided a vehicle comprising a composite crush can according to an aspect of the present invention. According to another aspect of the present invention, there is provided a method of forming a composite crush can according to an aspect of the present invention, the method comprising the steps of: cutting plies of composite material into a predetermined size; stacking a number of plies to achieve a composite material stack of a predetermined density; heating a mould cavity to achieve a predefined temperature at one or more points in the mould, the mould being shaped in accordance with a desired shape for the composite crush can; introducing the composite material stack into the heated mould; closing the mould with a predetermined closing force; compressing the composite material stack in the mould to cause the composite material stack to adopt a shape consistent with the shape of the mould to form the moulded composite crush can; statically compressing the moulded composite crush can; opening the mould and ejecting the moulded composite crush can; and cooling the moulded composite crush can. Optionally, the method further comprises a step of curing the moulded composite material and / or a polymerisation step. The curing and / or polymerisation step(s) may occur during the static compression step or as a separate step or steps. Optionally, the method further comprises making additional geometric modifications to the moulded composite crush can. Additional geometric modifications may include, but not be limited to, the addition of one or more further regions of increased thickness, such as but not limited to ribs, to the enclosing wall of the composite crush can. Making additional, optional geometric modifications to the moulded composite crush can increases the amount of design freedom available, enabling the composite crush can design to be customised to suit particular requirements. According to another aspect of the present invention, there is provided a crush can fora vehicle, the crush can comprising a first end and a second end, each disposed on a longitudinal axis of the composite crush can; and an enclosing wall extending between the first end and the second end, the enclosing wall comprising a continuous surface between the first and the second end; wherein the enclosing wall comprises a first region and two or more second regions, wherein the two or more second regions extend longitudinally at least part way between the first end and the second end and have an increased thickness as compared to the first region. Optionally, the crush can may comprise metal. Optionally, the crush can may comprise steel. Optionally, the crush can may comprise aluminium. The crush can according to this aspect of the present invention may have some or all of the optional features and associated benefits as mentioned above in relation to the aspect of the present invention relating to a composite crush can. Optionally, the crush can may comprise one or more buckling features. Optionally, the one or more buckling features may comprise an aperture and / or a lateral deformation of a part of the enclosing wall. The one or more buckling features may be configured to initiate buckling of the crush can in dependence on application of an impact force applied to the crush can. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 shows a perspective view of a composite crush can in accordance with embodiments of the invention, the composite crush can comprising a flange for attaching the composite crush can to a vehicle; FIG. 2 shows a side view of the composite crush can shown in Figure 1, in particular illustrating the tapered profile of the enclosing wall from a wider first end adjacent the flange, towards a narrower second end; FIG. 3A shows a plan view of the crush can of Figure 1, looking from the narrower second end of the crush can towards the wider first end; FIG. 3B shows a plan view of the crush can of Figure 1, looking from the flange and the wider first end, and into the cavity of the crush can towards the narrower second end; FIG. 4 shows a cross sectional view of the composite crush can shown in Figure 1; FIG. 5 illustrates a method of making the composite crush can according to embodiments of the invention; FIG. 6A shows a schematic view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises a plurality of generally cylindrical regions of increased thickness extending along the length of the internal surface and external surface of the composite crush can; FIG. 6B shows a schematic view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises a plurality of regions of increased thickness on the external surface of the composite crush can; FIG. 6C shows a schematic view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises a plurality of regions of increased thickness on the internal surface of the composite crush can; FIG. 7 shows a schematic view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises a plurality of regions of increased thickness on internal and external surfaces of the composite crush can; FIG. 8 shows a perspective view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises regions of increased thickness which are tapered in a first direction; FIG. 9 shows a perspective view of a composite crush can according to embodiments of the invention, in which the composite crush can comprises regions of increased thickness which are tapered in a second direction; FIG. 10 shows a perspective view of the composite crush can shown in Figures 1 to 5A, attached to a bumper beam to provide an energy absorption system for a vehicle; and FIG. 11 shows a vehicle in accordance with embodiments of the invention. DETAILED DESCRIPTION FIG. 1 shows a composite crush can 100 in accordance with an embodiment of the present invention. The composite crush can 100 of the present embodiment is a hollow, generally rectangular cuboid shape having a first end 102 and a second end 104, each disposed on a longitudinal axis 106 of the composite crush can 100. In the embodiment shown in Figure 1, each of the first end 102 and the second end 104 are generally rectangular, having rounded corners and rounded sections corresponding to the ends of individual “ribs” formed on the crush can 100 as will be explained. The rounded corners assist in reducing stress concentrations in the corner regions as compared to using sharp comers. The first end 102 of the composite crush can 100, which in use, is secured to the vehicle body, has a larger cross section than the second end 104 of the composite crush can 100 which, in use, is fixed to or positioned adjacent a bumper beam 1300, as shown in FIG. 10. An enclosing wall 108 extends between the first end 102 and the second end 104 to form a continuous surface between the first end 102 and the second end 104 of the composite crush can 100, and a cavity (not visible) therebetween, and defines the generally rectangular cuboid shape of the composite crush can 100. In the present embodiment, the shape of the enclosing wall 108 conforms to the generally rounded rectangularshape of each of the first end 102 and the second end 104 of the composite crush can 100 and as such comprises a top wall 110, a bottom wall 112, a first side wall 114 (not visible in Fig. 1) and a second side wall 116, with each of the aforementioned walls being contiguous with an adjacent wall via a rounded corner. In other embodiments, the enclosing wall 108 may be curved and may not comprise side and / or top / bottom walls. As the enclosing wall 108 at the first end 102 of the composite crush can 100 has a larger cross section than the enclosing wall 108 at the second end of the composite crush can, the enclosing wall 108 tapers inwardly from the larger first end 102 towards the smaller second end 104. In the present embodiment, a 5 degree taper is used. Tapering the cross section in this way provides an increasing amount of material available for absorbing impact forces along the longitudinal axis from the smaller second end 104, which is closest to the bumper beam 1300 towards the larger first end 102 of the composite crush can 100 which is secured to a body of a vehicle 1400. The first end 102 of the composite crush can 100 comprises a flange 118 which extends substantially perpendicularly from the enclosing wall 108 at the first end 102. The interface between the enclosing wall 108 8 and the flange 118 is bridged by a rounded joint 120 (or corner) which assists in reducing stress concentrations in the joint / corner regions as compared to using sharp corners. The flange 118 is attachable to a part of the vehicle body to secure the composite crush can 100 to the vehicle 1400. The flange 118 comprises a plurality of apertures, which in the present embodiment are first, second, third and fourth apertures 122a, 122b, 122c, 122d, through which bolts (not shown) may be inserted and subsequently inserted into correspondingly located apertures on a part of the vehicle body, to secure the composite crush can 100 to the vehicle 1400. The second end 104 of the composite crush can 100 comprises a generally planar surface and is adapted to be positioned against an internal surface of a bumper beam 1300 and may be bonded or otherwise attached to the internal surface of the bumper beam 1300. In the present embodiment, the second end 104 of the composite crush can 100 comprises a planar end wall 124 which closes off the enclosing wall 108 at the second end 104 of the composite crush can 100. In other embodiments, the second end 104 of the composite crush can 100 may not have an end wall 124 and may instead be open. The enclosing wall 108 comprises a first region 126 and two or more second regions 128a-e and 128c’-e’. The first region 126 is a part of the enclosing wall 108 that has a predefined thickness. In the present embodiment, the predefined thickness of the first region 126 is 4mm. The predefined thickness may vary between embodiments of the composite crush can 100 as it will be appreciated that selection of a predefined thickness will made based on factors such as the crush performance requirements of the composite crush can 100. The two or more second regions 128a-e and 128c’-e’ of the enclosing wall 108 have an increased thickness as compared to the first region 126. In the present embodiment, the predefined thickness at the thickest part of the second region 128 is 10mm. The two or more second regions 128a-e and 128c’-e’ may take numerous forms and are not limited to any particular size and / or shape. In the embodiment illustrated in Figure 1, the two or more second regions 128a-e and 128c’-e’ comprise ribs which extend the length of the enclosing wall 108 between the first end 102 and the second end 104 of the crush can 100. It will however be appreciated that the two or more second regions 128 may take a different form to the illustrated ribs, such as but not limited to being a different shape and / or having a different radius and / or thickness. For ease of description with reference to the Figures of this application, the two or more second regions 128a-e and 128c’-e’ will hereinafter be referred to as “ribs” 128a-e and 128c’-e’. The embodiment shown in Figure 1 comprises a single rib 128a, 128b located halfway along each of the top wall 110 and bottom wall 112, respectively and extending between the first end 102 and the second end 104 of the crush can 100. Accordingly, the ribs 128a, 128b on each of the top wall 110 and bottom wall 112 are located directly opposite to one another, across a cavity defined by the enclosing wall 108. The cavity is shown in FIG. 5. Each of the first side wall 114 and second side wall 116 comprises three spaced apart ribs 128c, 128c', 128d, 128d', 128e, 128e'which extend between the first end 102 and the second end 104 of the crush can 100. The prime notation designates ribs positioned on the second side wall 116. One of the three spaced apart ribs 128d, 128d' is located centrally on each side wall, i.e. halfway down each of the first side wall 114 and second side wall 116, relative to the respective adjacent top wall 110 and bottom wall 112. The remaining two 128c, 128c', 128e, 128e' of the three ribs on each wall are positioned either side of the centrally located rib 128d, 128d' on each side wall 114, 116, between the centrally located rib 128d, 128d' and a respective rounded corner that joins each of the first and second side walls to the top wall 110 and bottom wall 112, respectively. Each of the ribs 128 on each wall extends the full length of the enclosing wall 108 between the first end 102 and the second end 104. In the present embodiment, each rib 128 comprises a generally circular profile in cross section, defined by two semi-circular cross sections, with one semi-circular portion of the rib 128 projecting from each of the internal surface and the external surface of the first region 126 of the crush can 100, respectively. In FIG. 1, only the semi-circular projection on the external surface of the crush can 100 is visible. However, FIG. 3B shows the corresponding semi-circular projection of each rib 128a-e and 128c’-e’ protruding from the internal surface of the crush can 100. The second region 128a-e and 128c’-e’ (or regions 128a-e and 128c’-e’) may be formed on just on an external surface or an internal surface of the composite crush can 100. FIG. 2 illustrates the tapered profile of the enclosing wall 108 from the wider first end 102 adjacent the flange 118 towards the narrower second end 104. The tapered cross section provides an increasing amount of material available for absorbing impact forces along the longitudinal axis 106 from the smaller, second end 104 of the composite crush can 100 which is the first part of the can to absorb impact forces arising from a crush event, towards the larger, first end 102 of the composite crush can 100 which is attached to the body of the vehicle 1400. This impact absorbing effect is further improved with the provision of the ribs 128a-e and 128c’-e’ (only 128c’-e’ are clearly visible in FIG. 2) extending the length of the enclosing wall 108 of the composite crush can 100, because the ribs also increase the amount of material available for absorbing impact forces along the longitudinal axis 106 of the composite crush can 100. FIG. 3A shows a plan view of the external surface of the crush can 100 of FIG. 1, looking at the crush can 100 from the end wall 124 of the second end 104, towards the first end 102. FIG. 3B shows a plan view of the internal surface and a cavity 130 of the crush can, looking from the first, wider end 102 with the flange 118, towards the end wall 124 of the second, narrower end 102 of the crush can 100. As can be appreciated from FIGS. 3A and 3B, each of the ribs 128a-e and 128c’-e’ in the present embodiment extends from the first end 102 to the second end 104 of the can 100 in a generally cylindrical shape. Each cylindrical rib 128a-e and 128 c’-e’ is formed by the combination of a semi-circular projection extending away from the exterior surface of the first region 126 of the can 100 (as shown in FIG. 3A), and a corresponding semi-circular projection extending away from the interior surface of the first region of the can 100 and into the cavity 130 (as shown in FIG. 3B). In other embodiments, the ribs 128a-e and 128 c’-e’ may have a tapered cylindrical profile, for example, one which is tapered such that the cylindrical shape of each rib has a greater diameter at the first end 102 of the can, and tapers towards a narrower diameter at the second end 104 of the can 100. In other embodiments, the ribs may be formed by a projection only on the exterior surface of the can 100, or on the interior surface of the can 100. FIG. 4 shows a cross-section of the composite crush can 100 shown in FIGS 1-3B, and illustrates the generally cylindrical profile of each of the ribs (regions of increased thickness) 128a-e and 128c’-e’. The flange 118 is omitted in this cross-sectional view of the can 100. As explained above, each rib 128a-e and 128c’-e’ in the present embodiment is defined by two generally semi-circular projections projecting from each of the interior surface and the exterior surface, respectively of the crush can, such that each rib comprises a generally cylindrical shape which extends the length of the enclosing wall 108 of the can 100 between the first end 102 and the second end 104. In the present embodiment, each rib 128 has a constant radius along its length (i.e. between the first end and the second end of the composite crush can 100. The arrangement of the ribs 128a-e and 128c’-e’ in this embodiment is symmetrical about a notional midline of the composite crush can 100 such that each one of the three ribs 128c-e, 128c’-e’ on each side wall 114, 116 is positioned opposite to a corresponding one of the three ribs 128c-e, 128c’-e’ on the other side wall 114, 116 and the rib 128a on the top wall 110 is positioned directly opposite to the corresponding rib 128b on the bottom wall 112. The ribs 128 on each wall extend from each of the internal and external surfaces of each wall to provide the enclosing wall 108 with second regions 128a-e, 128 c’-e’ having an increased thickness as compared to the first region 126 of the enclosing wall 108 which does not have ribs (second regions 128a-e, 128 c’-e’ of increased thickness). Positioning the ribs 128a-e, 128 c’-e’ on the internal and external surfaces of the enclosing wall 108 provides the composite crush can 100 with additional strength and resistance to crushing by virtue of the increased amount of composite material in the can from the second regions 128a-e, 128 c’-e’ of increased thickness in the enclosing wall 108. FIG. 5 illustrates a method 400 of manufacturing a composite crush can in accordance with an embodiment of the invention. Embodiments of composite crush can 100 according to the invention comprise sheet moulding compound (SMC). The SMC comprises a polymeric matrix having a plurality of short, randomly-orientated fibres embedded therein. Although SMC is not isotropic per se, it is considered more isotropic than other composite fibres and the present inventors have found the specific selection of SMC to be beneficial in a crush can application as the inventors were able to determine that SMC absorbed more energy as compared to other composite materials, on the basis that when subjected to crush impact, SMC produced smaller pieces of debris as compared to other composite materials, indicative of a higher energy absorption. Embodiments of the invention may be formed from glass fibre sheet moulding compound and / or carbon fibre sheet moulding compound. In other embodiments, alternative compositions or materials may be used to form the crush can. It is known that the amount of energy absorbed by a composite crush can 100 per unit mass and / or per unit volume may be higher than for an equivalent metal crush can, thus enabling the length of the composite crush can 100 to be reduced as compared to the equivalent metal crush can. However, the use of sheet moulding compound (SMC) in embodiments of the present invention provides further benefits, including being relatively inexpensive, easy to handle during manufacturing and corrosion resistant. Sheet moulding compound (SMC) is also particularly useful in the present invention as its structure, namely the arrangement of fibres in the resin, allows for a more predictable shattering pattern of the can after impact, as compared to other materials. Referring to FIG. 5, in a first step 402 of the method 400, plies of SMC are cut into a pre-determined size from a quantity of room-temperature SMC. In a next step 404, multiple plies are stacked up and each stack (charge) is weighed to ensure compliance with a pre-determined density, and the weight of the stack adjusted if necessary. As an example, a pre-determined density may be between 1.0 g / cm3 to 1.8 g / cm3. Pre-forming of the SMC charges is not necessarily an essential step, but may be performed in one or more embodiments. In a subsequent step 406, a mould cavity is heated to achieve a predefined temperature at one or more points in the mould. It will be appreciated that the predefined temperature(s) may vary depending on the type of SMC used for the moulding process and / or other factors. The mould is shaped in accordance with the desired crush can shape. For example, one or more parts of the mould may be angled to produce a crush can comprising a taper, for example to form a draft angle to facilitate removal of a mould tool and / or to facilitate removal of the moulded crush can from the mould after curing. The mould may also be shaped to provide at least two or more second regions (“ribs”) 128a-e, 128 c’-e’ of increased thickness on an external surface of the enclosing wall as described and shown with reference to FIG. 3A and FIG. 3E3 above. For example, the internal surface of the mould may comprise at least two radial indentations into which SMC can flow during the moulding process to form radially shaped ribs that extend the length of the enclosing wall and project in a direction away from the hollow core of the composite crush can, such as illustrated in FIG. 3A and FIG. 3B. In a next step 408 each SMC stack (charge) is introduced into a bottom part of the open, heated mould cavity. One or more of the internal surfaces of the bottom part of the mould cavity may be angled ortapered to provide suitable draft angle for releasing the moulded crush can from the mould after curing. For example, a 5 degree draft angle may be used. It will be appreciated that the draft angle may vary between embodiments of the crush can, depending on other factors, such as but not limited to the overall size and shape of the resulting crush can, as well as the characteristics of the material being used for the moulding process. As an example, a draft angle may be a minimum of 1 degree for shallower parts. A draft angle of 5 degrees may be suitable for all parts, irrespective of the depth of the part. In a next step 410, the mould is closed and the closing force of the mould is set at a predetermined force depending on the material being moulded. As an example, a closing force of between 1,000 kN - 10,000 kN may be suitable. It is to be appreciated that this force may also vary depending on the number of parts per mould. For example, the closing force may be higher than this example range if there is a large number of parts per mould. In a next step 412, dynamic compression of the charge occurs during which the can is formed through the compression of a top part of the mould tool into the bottom part of the mould cavity. This dynamic compression causes the material to move and flow through the tool as the charge becomes compressed, and the shape of the can is formed. The top part of the mould tool may be shaped to provide at least two or more second regions of increased thickness on an internal surface of the enclosing wall. For example, the external surface of the top part of the mould tool may comprise at least two radial indentations into which SMC can flow during the moulding process to form radially shaped ribs that extend the length of the enclosing wall and project in a direction towards the hollow core of the composite crush can, such as illustrated in FIG. 3A and FIG. 3B. In a next step 414, static compression and / or curing and / or polymerisation occurs. It will be appreciated that the duration of this step will vary depending on a number of factors, including the material used for the charge, the thickness of the parts etc. As an example, this static compression / curing / polymerisation step may last between 30 to 90 seconds per mm thickness of material. Non-limiting examples of the curing process may include heating, cooling, chemical curing means and / or light exposure. In a next step 416, the mould is opened and the moulded composite crush can is ejected out of the mould. As a non-limiting example, ejection of the crush can may be achieved by applying pressure to the end wall of the composite crush can using a punch tool to remove the can from the mould. The next step 418 comprises a cooling phase and optionally further geometric modifications to the moulded crush can as well as any required machining and / or cleaning of the moulded can. FIGS. 6A to 6C show different configurations of ribs on a composite crush can according to non-limiting embodiments of the invention. It will be appreciated that the configurations of ribs illustrated, and other nonillustrated configurations according to other embodiments of the invention may be applied to composite or noncomposite crush cans, such as but not limited to metal crush cans. It will also be appreciated that in other embodiments, the configuration of ribs, including but not limited to their relative sizes, positions on the internal and / or external surfaces of the enclosing wall, shapes etc, may vary from the illustrated examples. Ribs may be located on any of the surfaces of the enclosing wall and in one or more embodiments, an equal number of ribs is provided per opposite wall (e.g. opposing side walls and / or opposing top and bottom walls) of the enclosing wall. FIG. 6A shows a schematic view of a cross section of a composite crush can 600 according to an embodiment of the invention. In this embodiment, a single rib 628 extends from both the internal and external surfaces of the enclosing wall of the composite crush can 600 to define a circular rib 628 approximately midway along each of the top wall 610 and bottom wall 612. In other words, the rib on the top wall 610 is located directly opposite the rib on the bottom wall 612 when viewing the composite crush can 600 in cross section. Each of the first side wall 614 and second side wall 616 is provided with two ribs 628. A first of the two ribs 628 is positioned between a notional longitudinal midline of the side wall and a rounded corner that joins each side wall to the adjacent top wall 610. A second of the two ribs 628 is positioned between the notional longitudinal midline of each of the side walls 614, 616 and a rounded cornerthat joins each side wall to the adjacent bottom wall 612. Each of the two ribs 628 extends from the internal and external surfaces of the first and second side walls 614, 616, respectively, to define two circular ribs on each of the firstand second side walls 614,616. The arrangement of the two ribs 628 on the first side wall 614 mirrors that of the arrangement of the two ribs on the second side wall 616 such that the two pairs of ribs on each side wall are positioned directly opposite to each other, on a cross-sectional view. In this embodiment, each rib 628 has a constant radius and height along its length. In other embodiments, the radius and height of each rib 628 may vary along its length. The ribs on each wall provide the enclosing wall 608 with second regions 628 having an increased thickness compared to the first regions 626 of the enclosing wall 608 which do not have ribs 628. Positioning the ribs 628 on both the internal and external surfaces of the enclosing wall 608 provides the composite crush can 600 with additional strength and resistance to crushing by virtue of the increased amount of composite material in the can from the second regions 628 of increased thickness in the enclosing wall 608. FIG. 6B shows a schematic view of a cross section of a composite crush can 700 according to an embodiment of the invention. In this embodiment, a single rib 728 extends from the external surface of the enclosing wall 708 approximately midway along each of the top wall 710 and bottom wall 712. Each of the first side wall 714 and second side wall 716 is provided with two ribs 728. A first of the two ribs 728 is positioned between a notional longitudinal midline of each of the side walls 714, 716 and a rounded cornerthat joins each side wall to the adjacent top wall 710. A second of the two ribs 728 is positioned between the notional longitudinal midline of the side wall and a rounded corner that joins the side wall to the adjacent bottom wall 712. The arrangement of the two ribs on the first side wall 714 mirrors that of the arrangement of the two ribs 728 on the second side wall 716 such that the two pairs of ribs 728 on each side wall 714, 716 are positioned directly opposite to each other, on a cross-sectional view. In this embodiment, each rib 728 has a constant radius and height along its length. In other embodiments, the radius and height of each rib 628 may vary along its length. The ribs 728 on each wall 710, 712, 714, 716 extend in a direction away from a notional centre line of the cavity 730 of the composite crush can 700 and provide the enclosing wall 708 with second regions 728 of increased thickness as compared to the first regions 726 of the enclosing wall 708 which do not have ribs 728. Positioning the ribs 728 on the external surface of the enclosing wall 708 provides the composite crush can 700 with additional strength and resistance to crushing by virtue of the increased amount of composite material in the can from the regions of increased thickness in the enclosing wall 708, but does not affect the inner dimensions of the composite crush can 700. FIG. 6C shows a schematic view of a cross section of a composite crush can 800 according to another embodiment of the present invention. In this embodiment, a single rib 828 extends from the internal surface of the enclosing wall 808 approximately midway along each of the top wall 810 and bottom wall 812. Each of the first side wall 814 and second side wall 816 is provided with two ribs 828. A first of the two ribs 828 is positioned between a notional longitudinal midline of the side wall and a rounded comer that joins each side wall to the adjacent top wall 810. A second of the two ribs 828 is positioned between the notional longitudinal midline of each side wall and a rounded corner that joins the side wall to the adjacent bottom wall 812. The arrangement of the two ribs on the first side wall 814 mirrors that of the arrangement of the two ribs on the second side wall 816 such that the two pairs of ribs on each side wall 814, 816 are positioned directly opposite to each other, on a cross-sectional view. In this embodiment, each rib 828 has a constant radius and height along its length. In other embodiments, the radius and height of each rib 628 may vary along its length. The ribs 828 on each wall extend in a direction towards a notional centre line of the hollow core of the composite crush can 800 and provide the enclosing wall 808 with second regions 828 of increased thickness on the internal surface as compared to the first regions 826 of the enclosing wall 808 which do not have ribs. Positioning the ribs on the internal surface of the enclosing wall 808 provides the composite crush can 800 with additional strength and resistance to crushing by virtue of the increased amount of composite material in the can from the regions of increased thickness in the enclosing wall 808, but does not affect the outer dimensions of the composite crush can 800. FIG. 7 shows a schematic view of a cross section of a composite crush can 900 according to another embodiment of the present invention. In this embodiment, each of the top wall 910 and bottom wall 912 comprises two ribs 928 positioned side by side on each of the top wall 910 and bottom wall 912, respectively, with one of the two ribs 928 being positioned on the internal surface of each of the top wall 910 and bottom wall 912, respectively, and the other of the two ribs 928 being positioned on the external surface of each of the top wall 910 and bottom wall 912. Each of the first side wall 914 and second side wall 916 comprises three ribs 928 positioned in series along the length of the first side wall 914 and second side wall 916, respectively. Of the three ribs 928 on each of the first side wall 914 and second side wall 916, the centre-most rib 928 is positioned on the external surface of each of the first side wall 914 and second side wall 916 and the two remaining ribs 928 located either side of the centre-most rib 928 are each positioned on the internal surface of each of the first side wall 914 and second side wall 916, respectively. Such a configuration of ribs 928 may be useful when positioning the crush can around one or more other components in a vehicle environment, for example for accommodating one or more vehicle components around the ribs 928 of the can. The ribs 928 in this embodiment are semi-circular in shape so as to form radially shaped ribs 928 protruding from the surface of each wall. However, it is to be appreciated that other rib 928 formations may be used to achieve the same technical effect as the radially shaped ribs 928 shown and described. FIG. 8 shows a side view of a composite crush can 1000 according to another embodiment of the present invention, in which the composite crush can 1000 comprises regions of increased thickness along the longitudinal axis 1006 of the composite crush can 1000 which are tapered in a first direction 1. In the present embodiment, the first direction 1 corresponds to a width direction relative to a wall of the crush can such that at the wider first end 1002 of the composite crush can 1000, the width of each rib is greater than the width of the rib 1028 at the narrower second end 1004 of the composite crush can 1000 and each rib 1028 consequently tapers from a wider portion at the first end 1002 of the composite crush can 1000 towards a narrower portion at the second end 1004 of the composite crush can 1000. In the present embodiment, a taper width of approximately 3 degrees is used. The narrower portion of each rib 1028 is formed using less material as compared to the wider portions of each rib 1028 meaning that the composite crush can 1000 comprises an increasing amount of material towards the wider, first end 1002 as compared to at the narrower second end 1004. The narrower second end 1004 is both tapered in its cross section and comprises narrower rib portions 1028 and thus comprises less material than the first end 1002 which is wider in its cross section and comprises wider rib portions 1028, thus utilising a greater amount of composite material. This arrangement provides less resistance to crushing at the narrower second end 1004 which may assist in initiating the crush process and provides an increasing resistance to crushing along the longitudinal axis 1006 of the composite crush can 1000 due to the increasing amount of material forming the composite crush can 1000 and its ribs towards the second end 1004. FIG. 9 shows a perspective view of a composite crush can 1100 according to another embodiment of the present invention, in which the composite crush can 1100 comprises regions of increased thickness 1128 which are tapered in a second direction 2. In the present embodiment, the second direction 2 corresponds to a height direction relative to a wall from which the regions of increased thickness 1128 project such that at the wider first end 1102 of the composite crush can 1100, the height of each rib 1128 is greater than the height of the rib 1128 at the narrower second end 1104 of the composite crush can 1100 and each rib 1128 consequently tapers from a taller portion at the first end 1102 of the composite crush can 1100 towards a shorter portion at the second end 1104 of the composite crush can 1100. In other words, the taller regions of each rib 1128 project from the enclosing wall 1108 to a greater degree than the shorter regions of each rib 1128. In the present embodiment, a taper width of approximately 3 degrees is used. The shorter, i.e. less high portion of each rib 1128 is formed using less material as compared to the taller portions of each rib meaning that the composite crush can 1100 comprises an increasing amount of material towards the wider, first end 1102 of the composite crush can 1100 as compared to at the narrower second end 1104. The narrower second end 1104 is both tapered in its cross section and comprises less high rib 1128 portions and thus comprises less material than the first end 1102 which is wider in its cross section and comprises taller rib portions, thus utilising a greater amount of composite material. This arrangement provides less resistance to crushing at the narrower second end 1104 which may assist in initiating the crush process and provides an increasing resistance to crushing along the longitudinal axis of the composite crush can 1100 due to the increasing amount of material forming the composite crush can 1100 and its ribs towards the second end 1104. It will be appreciated that in other embodiments, different arrangements of tapered ribs may be used. For example, a combination of ribs tapered in each of a first and second direction may be used, and / or one or more ribs may be tapered in both the first and the second direction. FIG. 10 shows a perspective exploded view of two composite crush cans 100 each being in accordance with the embodiment of composite crush can 100 described above in relation to Figures 1 to 4, attached to a bumper beam 1300 of a vehicle (shown in FIG. 11) to form an energy absorption system 1310. In particular, the narrower, second end 104 of each composite crush can 100 is attached to an internal surface of the bumper beam 1300 and the wider, first end 102 of the composite crush can 100 is attached to a part of the vehicle body via fasteners, such as bolts, inserted through each aperture on the flange 118 of each respective composite crush can 100 and into a corresponding aperture on the vehicle body. Fastening means such as nuts may engage with the fasteners, for example by engaging threads on each of the bolt and corresponding nut, to secure the composite crush can 100 to the body of the vehicle 1400. FIG. 11 shows a vehicle 1400 in accordance with an embodiment of the present invention. The vehicle may be an electric or hybrid vehicle. The vehicle 1400 may comprise an embodiment of composite crush can as described above. The vehicle 1400 may comprise an energy absorption system 1310 comprising an embodiment of composite crush can as described above. It is to be appreciated that whilst embodiments herein may refer to ribs disposed on or extending from one or more walls of the enclosing wall, the invention is not limited to any particular configuration of enclosing wall. For example, a crush can according to one or more embodiments of the invention may comprise an enclosing wall which is not defined by a top wall, bottom wall and / or side walls, but which may still comprise ribs disposed on or extending from regions of the internal and / or external surface(s) of the enclosing wall. For example, the enclosing wall may comprise a tapered, tubular construction having a continuous curved surface on which is provided one or more regions of increased thickness (ribs). It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A composite crush can for a vehicle, the composite crush can comprising:a first end and a second end, each disposed on a longitudinal axis of the composite crush can; andan enclosing wall extending between the first end and the second end, the enclosing wall comprising a continuous surface between the first and the second end;wherein the enclosing wall comprises a first region and two or more second regions, wherein the two or more second regions extend longitudinally at least part way between the first end and the second end and have an increased thickness as compared to the first region.

2. A composite crush can according to claim 1, wherein a cross section of the enclosing wall is configured to taper inwardly from the first end towards the second end.

3. A composite crush can according to claim 1 or 2, wherein the enclosing wall comprises a top wall, a bottom wall and first and second side walls.

4. A composite crush can according to any one of claims 1 to 3, wherein one or more of the two or more second regions is located on the top wall and / or the bottom wall.

5. A composite crush can according to anyone of claims 1 to 4, wherein one or more of the two or more second regions is located on the first side wall and / or second side wall.

6. A composite crush can according to claim 4, wherein the one of the two or more second regions on the top wall is located directly opposite a first further second region on the bottom wall.

7. A composite crush can according to claim 5 or 6, wherein one of the two or more second regions on the first side wall is located directly opposite a second further second region on the second side wall.

8. A composite crush can according to any one of claims 1 to 7, wherein the thickness of one or both of the two or more second regions in a first direction changes along the longitudinal axis of the composite crush can.

9. A composite crush can according to any one of claims 1 to 8, wherein the thickness of one or both of the two or more second regions in a second direction changes along the longitudinal axis of the composite crush can.

10. A composite crush can according to any one of claims 1 to 9, wherein one or more of the two or more second regions comprises a rib.

11. A composite crush can according to claim 10, wherein the ribs form a part of an external surface of the enclosing wall and / or part of an internal surface of the enclosing wall.

12. A composite crush can according to any one of claims 1 to 11, wherein each of the two or more second regions comprises a radial shape and / or comprises one or more vertices.5 13. A composite crush can according to any one of claims 1 to 12, wherein one or more of the two ormore second regions is integrally formed with respect to the enclosing wall, and / or wherein one or more of the two or more second regions is fixed to the enclosing wall.

14. An energy absorption system for a vehicle, comprising a composite crush can according to any of 10 claims 1 to 13.

15. A vehicle comprising a composite crush can according to any of claims 1 to 13.15Application No: GB2405943.8Examiner:Peter GardinerClaims searched: 1 to 15Date of search: 8 October 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X Y X X Y A X: 1-7,10,11,13-15; Y: 8,9 1,3-7,10-15 1-8,13-15 8,9 JP 2021139496 A (SUMITOMO CHEMICAL) See the whole document, in particular ribs 840 in figure 7 and paragraph 76. CN 117565809 A (GUANGDONG YUEGANG) See the whole document, in particular elongate reinforcements 200 in figures 1 and 2. US 6406088 Bl (TATE) See the whole document, in particular figure 3 and how the thickness of the composite wall increases along its length. US 7896411 B2 (KANO) See figures IB and 6A, in particular how the thickness of the ribs 70, 84 changes in two different directions along the longitudinal axis of the tubular body. EP 0793035 Bl (VW) See the semi-circular longitudinal beads in figure 1.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From B60R 0019 / 34 01 / 01 / 2006 F16F 0007 / 12 01 / 01 / 2006

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