Vehicle chassis platform

Abstract

A thermoplastic vehicle chassis platform (10) comprises upper floor panel 20, lower floor panel 30, transverse struts 22, and longitudinal struts 24 connecting the floor panels. The transverse struts

Description

Technical field of the invention The invention relates to a vehicle chassis platform comprising thermoplastic material; which may be a fibre filled and / or composite material. It also relates to a vehicle chassis comprising such a chassis platform; to a vehicle rolling chassis comprising such a chassis; to a vehicle comprising such a rolling chassis; and to a method of manufacturing such a vehicle chassis platform. Background to the invention Most motor vehicles sold worldwide are based on steel body structures and internal combustion power trains offering a maximum speed well over 130kmh / 80 mph. Such vehicles, designed for high speed travel over long distances on metalled roads, are assumed also to be suitable for use in developing world countries on earth roads, often on repeated trips over short distances. Developing world enterprises may struggle to afford the purchase and running costs of such vehicles. Where vehicle kits are provided for local assembly (often in “completely knocked down” form), the assembly process may be relatively unskilled, leading to minimal technology transfer. Furthermore, developing world countries may have very humid climates, which can cause serious corrosion in steel bodied vehicles. Vehicles for use in developing world countries do not need to be fast. If they are designed for a maximum speed below 50kmh / 30mph, and have an unladen mass of less than 550kg / 1120 pounds, they can be homologated under L7e regulations in many parts of the world. Alternatively, light duty N1 specifications allow a top speed of 100kmh / 50 mph. Such regulations allow the cost of the finished vehicles to be affordable for developing world markets; and for vehicle weight to be low enough to avoid making ruts and potholes in earth roads. Vehicles used for agricultural purposes in developing world countries often have fixed routes on which they travel repeatedly - maybe 32km / 20 miles from field to port, rail yard, or other distribution facility. This is a highly suitable environment for electric traction, as the vehicle is never far from a recharging point. Electric traction can offer low fuel costs; low maintenance costs; and no exhaust emissions at point of use. There is a need, therefore, for a form of vehicle chassis platform which is light in weight, corrosion resistant, and offers low running costs in return for limited speed and acceleration. Such a vehicle chassis platform should also be capable of being built by local labour, which is relatively unskilled; and if possible, should be capable of being recycled at the end of its life in a vehicle. Summary of the invention The invention is as set forth in the appended claims. Detailed Description of the Invention In order that the invention may be more clearly understood, embodiments thereof will now be described, by way of example only, with reference to the accompanying Figures, in which: Figure 1 is a perspective view of an assembled vehicle chassis platform according to an aspect of the invention; Figure 2 is an exploded view of a vehicle chassis comprising a platform as shown in Figure 1, according to a second aspect of the invention; Figures 3a to 3d are perspective and end views of longitudinal struts being part of the vehicle chassis platform shown in Figure 1; Figure 4 is a perspective view of a transverse strut being part of the vehicle chassis platform shown in Figure 1; Figure 5 is a perspective view of a lower floor panel being part of the vehicle chassis platform shown in Figure 1; Figure 6 shows a forward closure panel as shown in Figures 1 and 2; Figure 7 is a perspective view from below of an assembled vehicle chassis as shown in exploded form in Figure 2; Figure 8 is a perspective view of a rolling vehicle chassis according to a third aspect of the invention, comprising a vehicle chassis as shown in Figure 7; and Figure 9 is a side elevation view of a vehicle according to a fourth aspect of the invention, comprising a vehicle rolling chassis as shown in Figure 8. In this description, the terms “forward” and “backward” refer to a vehicle longitudinal axis (X in Figure 2); “left” and “right” refer to a vehicle transverse axis (Y in Figure 2); and “up” and “down” refer to a vehicle vertical axis (Z in Figure 2); all these axes being defined when the vehicle is standing level on a flat and horizontal road surface. Figure 1 shows an assembled vehicle chassis platform 10, comprising an upper floor panel 20, a lower floor panel 30, and forward (40) and rearward (50) closure panels. Left and right edges 20L, 20R of the upper floor panel are rolled over adjacent to outer edges of lower floor panel 30. These rolled edges strengthen the edges of the chassis platform against impact damage; stiffen the edges; and provide a better cosmetic finish compared with a cut edge. The rolled edges are added to the upper panel before the lower panel is bonded to it. The tapered form of the chassis platform as shown resists deformation by “parallelogramming”; allows space for wheel steering lock and suspension bump travel; and encourages dirt and water to slide off the underside of the chassis platform in use. The forward and rearward closure panels keep dirt, water, debris, insects and animals out of the space between upper and lower floor panels. Figure 2 is an exploded view, showing internal components of the chassis platform as well as the external components shown in Figure 1. In particular, transverse struts 22 and longitudinal struts 24 are assembled to the upper and lower floor panels, and impart strength and rigidity to the platform. Longitudinal struts 24 comprise upper U-section members 26 and lower U-section members 28. As can be seen in Figures 3a to 3d, members 26 and 28 are joined together to make longitudinal stuts 24; which have horizontal surfaces 24H and vertical surfaces 24V in use. Figure 2 also shows further components which are added to chassis platform 10 to build up chassis 100, as shown in Figure 7. In particular, top damper mounts 60F, 60R; centre spring mounts 70 (providing a rear mounting for a front axle spring and a forward mounting for a rear axle spring); and outer spring mounts 80F (for the front of a front spring) and 80R (for the rear mounting of a rear spring) allow a suspension system to be mounted to the chassis. Figure 4 shows the details of a transverse strut 22; which comprises a vertical face 22V; horizontal faces 22H1 and 22H2; and longitudinal end faces 22L1 and 22L2 (all defined in the strut’s orientation in use). Notches 22N facilitate bending of faces 22L1 and 22L2 without buckling or swelling at the comers. When such a strut is assembled into a chassis platform, it may be assembled with horizontal faces 22H facing backwards with respect to the direction of vehicle travel and with end faces 22L facing forwards; or with the horizontal faces facing forwards, and the end faces facing backwards. A combination of these arrangements is shown in Figure 2 - analysis has shown that this “opposite handed” combination optimizes chassis platform stiffness. As an alternative to this construction, the transverse struts may be made of box sections (not shown in the Figures), similar to the longitudinal struts. Figure 5 shows lower floor panel 30 and its central upper surface 30a, to which surface struts 22 and 24 may be assembled prior to addition of upper panel 20. Upwardly angled surfaces 30bL and 30bR are formed by folding panel 30 around longitudinal axes 30eL and 30eR respectively. Outer horizontal surfaces 30cL and 30cR are formed by folding panel 30 around longitudinal axes 30fL and 30fR respectively. Hence, outer edges 30gL and 30gR give the lower floor panel a width slightly less than that of the upper floor panel 20, allowing edges 20L and 20R to be rolled over adjacent to the edges of the lower floor panel as described above. Axes 30eL and 30eR comprise first left and right edges of the lower floor panel; axes 30fL and 30fR comprise second left and right edges of the lower floor panel; and outer edges 30gL and 30gR comprise third and outermost edges of the lower floor panel. Figure 6 shows a forward closure panel 40 and forward leaf spring mounts 80F. Top and bottom edges of the closure panel are rolled over the upper and lower floor panels respectively, to give bonding surfaces for adhesive and to seal the interior of the chassis platform. Figure 7 shows a perspective view from beneath of a vehicle chassis according to a second embodiment of the invention. Brackets 80F support front mountings of leaf springs for a front axle; centre mountings 70 support rear mountings of said front springs and front mountings of leaf springs for a rear axle. Brackets 80R support rear mountings for leaf springs for a rear axle. Numerals 60F and 60R denote upper mounting points for telescopic dampers - to optimize damper performance, they should be mounted substantially vertically. All of these suspension mountings have steel bushes e.g. 85F moulded or pressed in, to prevent chafing damage of steel mounting bolts against plastic chassis components; or cracking of plastic parts. Mounting bolts should be greased before insertion into these bushes so that the bolts do not rust in place. The bushes should have exterior splines to prevent rotation in situ and to assist in secure mounting; even if the hole in the plastic part is on top tolerance, and the steel bush is on minimal tolerance. Figure 8 shows a vehicle rolling chassis 200 according to a third aspect of the invention. This rolling chassis is fitted with front (21 OF) and rear (21 OR) leaf springs and axles (e.g. 220F). Telescopic dampers e.g. 230R and wheel and tyre assemblies 240F and 240R are also shown. Steel wheels would generally be used, as they are cheaper and more damage tolerant than cast alloy wheels. A steering system; a braking system; and differential gearing or wheel motors would clearly be required , but are not fundamental to the invention; so for clarity, they are not shown in the Figures. Leaf spring shackles 225F and 225R are shown. Although a leading shackle is shown for the front axle, it is often considered preferable to use a trailing shackle on a steered axle, to minimize bump steer. Figure 9 shows a vehicle 300 according to a fourth aspect of the invention, comprising a cab 310 (shown in outline only) and a rear body 320 comprising side walls 330 and a rear wall 340. Walls 330 and / or 340 may be arranged to pivot downwards for loading and / or unloading of cargo. Cab 310 may be new build; or may be recycled from an end of life vehicle. A method of manufacture of the vehicle chassis platform; chassis; rolling chassis; and vehicle will now be disclosed (the method of manufacture of the vehicle chassis platform being a fifth aspect of the invention). Each of the thermoplastic panels or brackets is made from moulded thermoplastic sheet material. Each panel or bracket may be marked out with edges and fold lines before being cut to initial shape, using for example a bandsaw; CNC routing cutter; laser cutter; or water jet cutting. Where steel bushes need to be pressed into brackets, this is most easily performed on a flat blank, rather than a folded part. Although the upper floor panel 20 is shown as being substantially flat (with rolled edges), other plastic parts need to be folded around fold lines into their final 5 forms. This may be achieved using, for example, a CR Clarke 1500D or E120 bending machine. All joints between plastic parts may be welded, bonded (for example using methyl methacrylate adhesives), screwed, or bolted together. Diverse joining techniques may be used in different joints as required. Welding is good for recyclability; bonding less so. 10 The order in which parts are folded into their final shapes is a matter of experience; and is not fundamental to the invention. The cab, cab door, dashboard, and seating design follow conventional light truck designs. An advantage of the use of thermoplastic panels is that their light weight provides a virtuous circle; for example, the complexity and expense of power assisted steering may not be considered to be 15 necessary. The embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

03 07 251. A vehicle chassis platform comprising an upper floor panel, a lower floor panel, and intermediate struts connecting the two floor panels, wherein: the floor panels and struts are made of thermoplastic material;5 the struts are formed at upper and lower ends so that said ends comprisefaces parallel to the floor panels and an intermediate portion between the end faces is substantially vertical in use;and the intermediate struts comprise two longitudinal struts adjacent to left and right sides of the floor panels, and transverse struts which extend to substantially perpendicularly to the longitudinal struts;characterized in that: the lower floor panel is angled upwards at first left and right edges at an acute angle to the horizontal; and is then angled outwards again at second left and right edges outboard of the first left and right edges;so that the outermost or third left and right edges of the lower floor panel lie15 parallel to the upper floor panel, and adjacent to the outermost left and rightedges of the upper floor panel.

2. K vehicle chassis platform according to claim 1, wherein at least one of the thermoplastic floor panels or struts is made of fibre filled material.

203. A vehicle chassis platform according to claim 1 or claim 2, wherein at least one of the thermoplastic floor panels or struts is made of composite material.

4. A vehicle chassis platform according to any previous claim, wherein the 25 upper floor panel, the struts, and the lower floor panel are joined togetherby bonding, welding, riveting, or by threaded fasteners; or by any combination of these techniques.

5. A vehicle chassis platform according to any preceding claim, wherein at 30 least one transverse strut has elements folded around two mutuallyperpendicular axes.03 07 256. A vehicle chassis platform according to claim 5, wherein the at least one transverse strut has flat faces in vertical, transverse, and longitudinal planes.5 7. A vehicle chassis platform according to any previous claim, wherein thelower and upper floor panels are substantially parallel over at least the majority of their area; and are substantially equal in net length and width.

8. A vehicle chassis platform according to any previous claim, wherein the to longitudinal struts are formed into box sections.

9. A vehicle chassis platform according to claim 8, wherein the longitudinal box sections comprise opposite handed II sections which are joined together with overlapping joints.1510. A vehicle chassis platform according to any previous claim, wherein the transverse struts are formed into box sections.

11. A vehicle chassis platform according to any one of claims 1 to 9, wherein20 the top and bottom horizontal faces of at least one transverse strut areinstalled facing forwards in use.

12. A vehicle chassis platform according to any one of claims 1 to 9, wherein the top and bottom horizontal faces of at least one transverse strut are 25 installed facing backwards in use.

13. A vehicle chassis platform according to claim 11 or claim 12, wherein the folded top faces of the struts lie parallel to and adjacent to the upper floor panel; and the folded bottom faces of the struts lie parallel to and adjacent30 to the lower floor panel.

14. A vehicle chassis platform according to any previous claim, further comprising front and / or rear transverse closure panels to close forward and / or rearward gaps between the upper and lower floor panels.03 07 2515. A method of manufacturing a vehicle chassis platform comprising: moulding and / or cutting upper and lower floor panels from thermoplastic sheet material; moulding and / or cutting strut parts from thermoplastic sheet 5 material; forming struts from strut parts by folding and joining as required;folding the lower floor panel; and joining the completed struts to the floor panels;wherein the upper and lower floor panels are also joined to each other; and the struts have faces which are parallel to the upper and lower floor panels to and are joined thereto during platform assembly; and the struts also havefaces which are perpendicular to the upper and lower floor panels when the struts are assembled to the floor panels.

16. A vehicle chassis comprising a vehicle chassis platform according to any 15 one of claims 1 to 14, wherein formed thermoplastic suspension mountingsare attached to the underside of the lower floor panel.

17. A vehicle chassis as claimed in claim 16, wherein the suspension mountings are box sections.2018. A vehicle rolling chassis comprising a chassis according to claim 16 or claim 17, wherein leaf springs are attached to the suspension mountings, and live axles comprising wheels and tyres are attached to the leaf springs.25 19. A vehicle comprising a rolling chassis according to claim 18, a battery packand / or a fuel cell, a motor, a cab, and a load bay comprising substantially vertical front, side, and rear walls.

20. A vehicle comprising a rolling chassis according to claim 18, a fuel tank, an 30 internal combustion engine drive train, a cab, and a load bay comprisingsubstantially vertical front, side, and rear walls.

21. A vehicle according to claim 19 or claim 20, wherein the vehicle is a pickup truck, and the rear wall and / or side walls are horizontally hinged and can be opened downwards.5 22. A vehicle according to claim 19 or claim 20, wherein the vehicle is a van,and the rear wall and / or side walls comprise hinged and / or roller doors.

23. A vehicle according to claim 19 or claim 20, wherein the vehicle is a personnel carrier, comprising seating in the load area, and hinged doors in to the rear wall and / or side walls.03 07 25

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