Abstract:
A vehicle with a load space to provide a chassis comprising a framework ( 10 ) comprising a pair of spaced-apart elongate longitudinal members ( 12, 14 ) connected by a pair of spaced-apart elongate lateral members ( 20, 22 ) and bracing for the thus-defined framework, a rear suspension attached to the rearmost lateral member ( 20 ) and comprising a trailing-arm arrangement ( 52 ), and a front suspension attached to the front most lateral member ( 22 ) and comprising a leading-arm arrangement ( 58 ). This creates a rigid core for the chassis, which also provides all four suspension mounting points.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to vehicles and the design of their chassis. 
       BACKGROUND ART 
       [0002]    Our earlier patent applications WO2009/122178 and WO2010/149981 dealt with the design of a lightweight, low cost chassis that was particularly suitable for use in a lightweight city car. That chassis comprises a three-dimensional framework of tubular-section members reinforced with composite panels so as to create a chassis that is strong, rigid and light and which can be designed around a wide range of vehicle shapes. 
       SUMMARY OF THE INVENTION 
       [0003]    One vehicle shape to which these design principles can be extended is a vehicle having a significant flat load space. Part of the rigidity of the chassis of WO2009/122178 and WO2010/149981 comes from its three-dimensional structure, so although the load space can be designed as a generally flat area in the centre of a three-dimensional structure, there is an opportunity to refine the design so as to extend the benefits of the design principle to this context. 
         [0004]    Thus, the present invention provides a vehicle comprising a chassis, comprising a framework comprising a pair of spaced-apart elongate longitudinal members connected by a pair of spaced-apart elongate lateral members, and bracing for the thus-defined framework, a rear suspension attached to the rearmost lateral member and comprising a trailing-arm arrangement, and a front suspension attached to the frontmost lateral member and comprising a leading-arm arrangement. 
         [0005]    This creates a rigid core for the chassis, which also provides all four suspension mounting points. The chassis can include members extending beyond the core (and usually will) but these need not be as rigid (and hence as heavy) as the core, as they do not need to carry suspension loads. The result is a significant saving of materials and weight in the overall structure. 
         [0006]    The elongate members are preferably substantially straight, and can be an open channel section or a tubular section such as a box section or circular section. Naturally, we prefer that the thus-defined framework is flat. 
         [0007]    The bracing can comprise cross-members extending within the framework. These can extend from one lateral member to the other, ideally diagonally. Alternatively, or preferably in addition, the bracing can comprise a panel securely attached to the framework such as via adhesive bonding. The panel is ideally flat, at least in the region attached to the thus-defined framework. It can be of a composite material, such as a glass- or carbon-fibre reinforced composite, or plywood (such as engineered composite plywood), or of other suitable materials. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; 
           [0009]      FIG. 1  shows the framework forming part of the chassis of the present invention; 
           [0010]      FIG. 2  shows the framework with the bracing panels attached; 
           [0011]      FIG. 3  shows the chassis from beneath, with the suspension attached; and 
           [0012]      FIG. 4  shows the complete vehicle. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0013]    Referring to  FIG. 1 , the chassis framework  10  of the present invention is built up around a central rigid core which includes two longitudinal members  12 ,  14  which run from a rear of the vehicle to the front of the load space, just inboard of the rear wheel arches  16 ,  18 , and two lateral members  20 ,  22  which run from one side of the vehicle to the other side The lateral members  20 ,  22  thus cross the longitudinal members  12 ,  14 , doing so perpendicularly. A box is therefore formed at the centre of the vehicle by these four members. 
         [0014]    As noted, the longitudinal members  12 ,  14  run inboard of the wheel arches  16 ,  18  and are thus spaced inwardly from the edges of the vehicle. The lateral members  20 ,  22  extend across the width of the vehicle and thus (save for jointing arrangements) extend beyond the longitudinal members. A pair of outer members  24 ,  26  thus run between the ends of the lateral members  20 ,  22 . These do of course define a further box framework at the centre of the chassis. 
         [0015]    The longitudinal members  12 ,  14  are I-beam sections, and the lateral members  20 ,  22  are a slanted I-beam section. The rear lateral member  20  slants upwardly toward the rear of the vehicle, whereas the front lateral member  22  slants upwardly towards the front of the vehicle. The outer members  24 ,  26  are made of C-section beams. The use of open channel sections in this area of the chassis assists greatly in allowing water to leave the structure, mud to be cleaned off, and so on. Thus, the chassis can be left in a cleaner state after off-road work such as wading and the like, reducing the likelihood or the rate of corrosion. 
         [0016]    This central frameworks are then built up into a useful chassis shape by way of uprights  28 ,  30 , runners  32 , and other members which define the side walls of the load space. A front section  34  is attached to the central frameworks and supports a personnel cab. 
         [0017]    The central frameworks are reinforced with a number of bracing structures. A first is shown in  FIG. 1  and consists of a pair of diagonal bracing struts  33 ,  35  extending across the diagonals of the rectangle defined by the longitudinal members  12 ,  14  and the lateral members  20 ,  22 , joining at the centre of the rectangle. A second is shown in  FIG. 2  and consists of a panel  36  which is adhesively bonded to the longitudinal members  12 ,  14 , the lateral members  20 ,  22 , and the outer members  24 ,  26 . It is also bolted to them via bolts  38  for additional security. Both arrangements increase the rigidity of the central frameworks and make them suitable for bearing cargo and suspension loads, and increase the rigidity of chassis. Other panels  40  are attached to the remaining regions of the chassis  10 , partly to provide floors, walls etc for the load space and the cabin but also to provide bracing for the remaining parts of the structure and thus improve their strength and its rigidity. 
         [0018]    The chassis as shown in  FIG. 2  thus comprises a load space with walls on three sides (i.e. all but the rear edge, where a tailgate would normally be provided). Towards the rear of the two side walls, there are intrusions in the form of the wheel arches  42 . These and the side walls give the framework around the load space a three-dimensional character which, together with the bracing by the various panels tends to further strengthen the chassis. A cabin chassis section  44  extends from the front of the load space, in the form of a three-dimensional framework braced with flat panels providing a largely flat upper surface to act as the floor of the cabin. A step part-way along the cabin floor delineates a frontal lower section  46  which can act as a footwell in front of a slightly higher section  48  which includes an aperture  50  to accommodate an upper part of the engine, above which seating can be provided. 
         [0019]      FIG. 3  shows the underside of the chassis  10  with the suspension attached. A pair of trailing-arm suspension arms  52  are attached to the rear lateral member  20  so as to place a rear wheel hub  54  in each of the rear wheel arches  42 . Each trailing arm  52  is supported by a spring and damper unit  56  which extends upwards from a free end of the trailing arm  52  to a mounting point in the upper part of the wheel arch  42 . Each trailing arm  52  has a pair of pivot points at its front which are attached to mountings provided on the rear lateral member  20  to allow the trailing arm to swing upwards and downwards (subject to the spring and damper units  56 ). 
         [0020]    At the front, a pair of leading-arm suspension arms  58  are likewise attached to the front lateral member  22 . Each leading arm  58  is supported by a spring and damper unit  60  which extends upwards from a free end of the trailing arm  58  to a mounting point on the underside of the cabin section  44 . Each leading arm  58  has a pair of pivot points at its rear which are attached to mountings provided on the front lateral member  22  to allow the leading arm to swing upwards and downwards (subject to the spring and damper units  60 ). Wheel hubs  62  are provided on the end of the leading-arms  58 . 
         [0021]    In this way, the suspension for the vehicle is attached directly to the central rigid box of the chassis. Suspension loads can therefore be carried with ease, providing a stable ride and handling characteristic and reducing the need for great strength (and hence weight) in more remote parts of the chassis such as the cabin. The use of a front leading suspension arm and a trailing rear suspension arm, combined with the bonding of a rigid stabilised composite panel to the load floor framework, results in a considerably smaller, lighter and stiffer central torsion box into which the suspension torsion and bending loadings are resolved. 
         [0022]      FIG. 4  shows the complete vehicle. The chassis  10  supports a complete cabin  64  to the front of the vehicle, and the load space to the rear has additional side walls  66  and a tailgate  68 . Wheels  70  are provided on the wheel hubs  54 ,  62 . 
         [0023]    It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.