Abstract:
The provision of impact structures is difficult in the case of small vehicles, due to the shortage of working depth. We propose to use the wheel and tyre as part of the deformable structures, which reduces the overall weight of the vehicle and requires little or no additional space in which to provide the impact structures. There is still a need to control the movement of the wheel under impact, but we have found that this can be done by appropriate design of the suspension components so that they react in a defined manner to an impact and guide the wheel in the correct manner. The present invention therefore provides a vehicle comprising a chassis, at least one wheel, and a hub carrier on which the wheel is mounted, together with a suspension connecting the hub carrier to the chassis that includes a plurality of first links extending towards the chassis in at least one of an inward or an upward direction and at least one second link extending towards the chassis in a longitudinal direction, and a crushable structure attached to the chassis at a location aligned with a path of the wheel under impact after collapse of the longitudinally extending link.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to impact structures (or crash structures) for vehicles. 
       BACKGROUND ART 
       [0002]    Vehicle impact structures are designed to absorb the energy of an accident in which the vehicle is involved, dissipating the energy safely in a manner that decelerates the vehicle at a controlled rate. Typically, they will involve one or more sacrificial parts (which may also perform other functions during normal use of the vehicle) which crush or are otherwise deformed as a result of the impact. These parts are usually located to the front and to the rear of the vehicle, so that they receive the impact prior to it reaching the passenger cell. 
       SUMMARY OF THE INVENTION 
       [0003]    The provision of such structures is difficult in the case of small vehicles such as urban city cars, typically styled to have very short front and rear overhangs to allow them to cope with urban mobility restrictions, parking and traffic flow considerations while retaining good handling qualities. There is, quite simply, insufficient space to provide these structures. 
         [0004]    We propose to use the wheel and tyre as part of the deformable structures. Previously, there have been proposals for structures that catch or otherwise interact with the wheel and/or tyre, but this has been from the viewpoint of having to restrain the wheel from entering the passenger cell during impact. Examples include U.S. Pat. No. 6,364,358, WO2009/077079 and US2003/0141712, all of which add to the weight of the vehicle by including a structure that interacts with the wheel in order to direct its motion under impact. Such structures offer a benefit to the passenger in terms of a reduced likelihood of injury during an impact, but do so in a manner that calls for additional weight without contributing to the impact performance of the vehicle (other than preventing intrusion). By incorporating the wheels into the impact structure of the vehicle, we reduce the overall weight of the vehicle and require little or no additional space in which to provide the impact structures. There is still a need to control the movement of the wheel under impact, but we have found that this can be done by appropriate design of the suspension components so that they react in a defined manner to an impact and guide the wheel in the correct manner. 
         [0005]    The present invention therefore provides a vehicle comprising a chassis, at least one wheel, and a hub carrier on which the wheel is mounted, together with a suspension connecting the hub carrier to the chassis that includes a plurality of first links extending towards the chassis in at least one of an inward or an upward direction and at least one second link extending towards the chassis in a longitudinal direction, and a crushable structure attached to the chassis at a location aligned with a path of the wheel under impact after collapse of the longitudinally extending link. 
         [0006]    By integrating the design of the crushable structure into the suspension design in this way, the weight of the crushable structure can be minimised and rather than just controlling the movement of the wheel under impact in order to keep it from entering the passenger cell, the collapse of the wheel and suspension components can be employed as an active part of the energy absorption processes of the vehicle. This allows the front and rear sections of the vehicle to be optimised accordingly, allowing reductions in the weight and length of the vehicle as a whole while maintaining the necessary levels of impact resistance. 
         [0007]    The chassis can be one that is made up of a framework of interconnected tubular members, preferably including planar composite panels bonded to the tubular members. The crushable structure can then be a tubular member forming part of the framework, ideally is substantially co-linear with at least part of a tubular member of the framework extending longitudinally along a majority of the length of the vehicle. Often, the framework will include a tubular member extending longitudinally with respect to the vehicle from a point ahead of the wheel to a point behind the wheel, formed with at least one bend ahead of the wheel to define a region ahead of the bend which is laterally aligned with the wheel and a region behind the bend which is located laterally inboard of the wheel, in which case the crushable structure is preferably connected to the tubular member substantially at the bend, and can be substantially co-linear with the region of the tubular member that is ahead of the bend. 
         [0008]    The crushable structure can comprise a pair of tubular members, aligned vertically one above the other. These can be joined to the chassis at substantially the same location, from which they diverge, ideally at an acute angle to each other. The lower of the two tubular members forming the crushable structure is preferably substantially horizontal. 
         [0009]    Crushable structures formed of at least one tubular member can include an end cap, ideally having a flat outer surface. In a variant of this idea, the end cap may be angled, being closer to the vehicle centreline at an edge closer to the wheel, and further from the centreline at an edge more remote from the wheel. 
         [0010]    The chassis can also include a laterally-extending crossbar located behind a rearmost extent of the wheel, integrated into the framework where relevant. This will work with the other elements of the impact structure, absorbing lighter impacts without allowing the wheel and crushable structure to be involved and thus minimising the damage to the vehicle (and associated repair costs). 
         [0011]    The end of the crushable structure proximate the wheel can have a convex profile substantially matching a concave outer radial profile of the hub, thus allowing the two to interengage or interlock under impact. The end of the crushable structure proximate the wheel can be adapted to pierce the tyre to assist with this. 
         [0012]    The first links within the suspension can include an upwardly extending link in the form of a spring and damper unit. They can also include an inwardly extending link that comprises a wishbone attached to the hub carrier in two locations and attached to the chassis at one location. These two locations are ideally spaced horizontally. A suspension of this type is usually robust enough to provide reliable guidance to the wheel under impact while the second link collapses. 
         [0013]    The wheel may be a front wheel of the vehicle, or a rear wheel of the vehicle. The invention will usually be applied on both sides of the vehicle, and may be applied to both the front and rear wheels. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; 
           [0015]      FIG. 1  shows a horizontal sectional view of a suspension and crush structure of a rear wheel of a vehicle according to the present invention; 
           [0016]      FIG. 2  shows a view from one side of the suspension and crush structure of  FIG. 1 ; 
           [0017]      FIG. 3  shows a view from above of a suspension and crush structure of a front wheel of a vehicle according to the present invention; 
           [0018]      FIG. 4  shows a view from above of an alternative rear chassis and suspension structure according to the present invention; 
           [0019]      FIG. 5  shows a perspective view of a further alternative rear chassis and suspension structure according to the present invention; 
           [0020]      FIGS. 6 and 7  show top and side views (respectively) of the rear chassis and suspension structure of  FIG. 5 ; 
           [0021]      FIG. 8  shows a schematic view from above of a further embodiment; 
           [0022]      FIG. 9  shows a schematic view from above of a still further embodiment; 
           [0023]      FIG. 10  shows a schematic view form one side of the embodiment of  FIG. 9 ; 
           [0024]      FIG. 11  shows a schematic perspective view of a yet further embodiment; and 
           [0025]      FIG. 12  shows a variant on the embodiment of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0026]      FIGS. 1 and 2  show an embodiment of the invention in the form of a rear chassis and suspension. The chassis is in the form of a framework of tubular steel members, reinforced with composite panels in the manner disclosed in our application WO2009/122178 which is hereby incorporated by reference and to which the skilled reader is specifically directed for a fuller understanding of the present invention. Part of the chassis framework  10  is shown in  FIGS. 1 and 2 , and a rear wheel  12  of the vehicle is attached via a suspension arrangement  14 . The suspension arrangement is largely as described in our earlier application WO2010/100412, with a pair of lateral arms  16 ,  18  extending away from a single hard mounting point  20  on the chassis  10  (not shown) and towards the hub carrier  22  for the wheel  12 . A further control arm  24  extends rearwardly from a second hard mounting point  26  on the chassis  10  to the hub carrier  22 , and a spring and damper unit  28  extends obliquely upwardly from the hub carrier to a hard mounting point  30  on the chassis framework  10 . In combination, these suspension elements provide the car with good ride and handling capabilities using a minimum of space and parts. 
         [0027]    The rear wheels  12  are most likely to be of influence during a collision from the rear, generally along the direction of arrow  32 . Minor impacts of this type will be taken up by deformation of the rear bodywork and crush structures, but those above a certain threshold will reach the rear wheels and pass impact forces to them. Our analysis shows that this will likely cause the further control arm  24  to buckle and for the wheel to rotate around the suspension hard point  20  to which the lateral arms are attached. This will cause the wheel to move generally forwards, but along a trajectory that is predictable. 
         [0028]    Existing “tyre catcher” structures are aimed at deflecting this movement of the wheel and tyre so that it does not impinge into the cabin and (potentially) cause injury to the driver and/or passengers. According to this example, however, a tyre-catching structure  34  is placed in the path of the wheel as determined by the suspension components in order to engage with the wheel  12  and interrupt its forward motion. The tyre-catcher  34  is attached to the chassis framework  10  and can therefore transmit forces directly into the chassis; it may also include crush structures such as a cylindrical tube of a circular or other cross-section. In this way, further collapse of the wheel and the tyre catcher  34  will contribute to the vehicle&#39;s energy absorption, but principally the forces will be transmitted into the chassis and therefore around the vehicle occupants instead of through them. 
         [0029]      FIG. 3  shows a schematic view of the front suspension. The front wheel  50  is attached to the chassis framework  10  by suspension arms, which (in this case) consist of a lateral arm  52  which extends inwardly from the hub carrier  54  for the front wheel  50  to a suspension hard point  56 , a longitudinal arm  58  which extends rearwardly and slightly inwardly from the hub carrier  54  to a further suspension hard point  60  on the chassis framework  10 , and a spring and damper unit (not shown) which extends upwardly from the hub carrier to a hard point on the chassis framework  10 . Under a frontal impact along the direction of arrow  62 , the longitudinal suspension arm  58  will (eventually) buckle and collapse, leaving the lateral arm  52  to guide the wheel  50 . A front tyre catcher  64  is provided to interrupt this motion and allow the impact energy to be absorbed by a combination of collapse of the wheel, crushing of the tyre catcher, and transmission of the forces through the chassis framework and hence around the vehicle occupants. 
         [0030]    The frontal section of this chassis framework  10  includes a bend  66  in the chassis rail  68 , to allow the rail  68  to pass along the outside of the vehicle in the midsection between the two wheels, and between the front wheels. Thus, the bend  66  allows the rail  68  to divert inwardly so as to sit laterally inboard of the front wheel  50 . The rear section of the chassis framework ( FIGS. 1 and 2 ) also has a bend  36  in the (same) chassis rail  68  but in this case the rail  68  deflects upwardly to pass above the rear wheel  12 . In both cases, the respective tyre catcher  64 ,  34  is attached to the chassis rail  68  at the bend  66 ,  36  so that forces received by the tyre catcher  64 ,  34  are transmitted into the chassis framework  10 . To assist with this, the tyre catchers  64 ,  34  are generally aligned with the chassis rail  68  behind the bend  66 ,  36  so as to transfer the forces easily. 
         [0031]      FIG. 4  shows a further example being a development of the example of  FIGS. 1 to 3 . The chassis framework  100  includes (as before) a chassis rail  102  that extends longitudinally along the vehicle and deflects inwardly and upwardly at a bend  104  to sit behind and above the rear wheel  106 . A tyre catcher  107  extends from the chassis rail  102  at the bend  104 , towards the wheel  106 . It is aligned to continue in-line with the chassis rail  102  so that impact forces received by the tyre-catcher  107  are transmitted into the chassis framework satisfactorily. It ends with an end-cap  109 . An engine  108  sits in the rear section of the chassis, supported by the chassis framework  100  via engine mounts (not shown), behind the passenger cabin  110  with seats  112 . The chassis rail  102  ends at the rear of the vehicle where it is connected to a cross-bar  114  via an in-line crushable section  116 . The cross-bar  114  extends horizontally across the rear of the vehicle, and is connected on the other side to a corresponding chassis rail (not shown) on the other side of the vehicle via a second crushable section. The crushable sections  116  may comprise a hollow tubular length of a cylindrical or other cross-section, and ideally form distinct sections from the chassis rail  102  so that the can be replaced after being called into service. 
         [0032]    In a rear impact, the likely first point of contact (after deformation of body panels and the like) will be with the cross-bar  114 . This will absorb some impact energy of itself, with further impact energy being absorbed by the crushable sections  116 . Further impact energy is likely to result in contact with the wheels  106 , deforming them and absorbing energy as described above. The cross-bar  114  is (in this example) wide enough to contact the wheels if deformed far enough and thus may assist in transferring impact energy into the wheels and thus around the passenger compartment  110 , depending on the manner in which it is deformed. 
         [0033]      FIGS. 5 to 7  show a further example of the rear section of a vehicle. The chassis framework  150  in this case has two longitudinal chassis rails on either side, a lower rail  152  and an upper rail  154  located generally above the lower rail  152  for at least the major part of its length. At the rear of the car, the lower rail  152  bends upward to meet the upper rail  154 , where it is jointed with the upper rail  154 . At the bend  156 , a crushable tyre catcher  158  is joined to the lower rail  152  and extends rearwardly towards the rear wheel  160 , ending with a flat transverse end-plate  159 . As before, the tyre catcher is of a crushable nature, formed (in this case) of a circular section hollow cylindrical tube of a controlled diameter and thickness to trigger a controlled linear collapse at a suitable level of impact force. The wheel is supported by a suspension arrangement  161  as shown in  FIGS. 1 and 2 . 
         [0034]    The upper rail  154  extends to a region above and just inboard of the wheel  160 , where it is connected to a co-linear crush structure  162  via butt-plates  164  which are bolted together to create a releasable join between the crush structure  162  and the upper rail  154 . A similar arrangement of butt-plates  166  at the rear of the crush structure  162  connects it to a cross-bar  168 . As with the tyre catcher  158 , this is of a circular section hollow cylindrical tube of a controlled diameter and thickness, to trigger a controlled linear collapse at a suitable level of impact force. A similar structure is provided on the opposite side of the car. 
         [0035]    In an impact, the cross-bar  168 , the wheel  160  and the tyre catcher  158  will react as described above with reference to  FIGS. 1 to 4 . After an impact which is serious enough to involve the crush structure  162  but not serious enough to deform the chassis framework  150 , the butt-plates  164  can be disconnected in order to remove the crush structures  162  and the cross-bar  168  (which is likely to also need replacement) and replace these with new undeformed items. 
         [0036]    In this way, the cross-bar  168  &amp; crush structure  162 , the wheels  160 , the suspension  161 , and the tyre catchers  158  act together to absorb the most possible impact energy whilst occupying the minimum necessary space. 
         [0037]      FIGS. 8, 9, 10 and 11  show alternative arrangements. The chassis framework  200  again includes a chassis rail  202  which runs longitudinally with respect to the car and which includes a tyre catcher  207 , extending from the chassis rail  202  at a point  204  where it bends inwardly to sit behind a rear wheel  206 . In all the versions shown in  FIGS. 8 to 11 , this comprises a pair of tubular members  208 ,  210 , aligned vertically one above the other, and which together define the tyre catcher  207 . In  FIGS. 8 and 9 , being views from above, this means that the lower tubular member  208  is obscured by the upper tubular member  210 . The two tubular members  208 ,  210  are joined to the chassis at substantially the same location  204 , from which they diverge. The lower tubular member  208  extends generally and substantially horizontally towards the wheel  206 , while the upper tubular member  201  extends at an acute angle upwardly. Both tubular members  208 ,  210  end at a vertically-aligned point, and a single end cap  212  in the form of a vertical plate is attached to the two ends. 
         [0038]    The embodiments of  FIGS. 9 and 11  differ in that the two tubular members  208 ,  210  are arranged so as to extend outwardly relative to the chassis rail  202 . This allows the end points and the end cap  212  to be located correctly relative to a wheel  206  set on a slightly wider track. To provide additional bracing and stability, the end cap  212  in these embodiments includes an inward extension  214  that attaches to the chassis framework  200 . 
         [0039]    The embodiments of  FIGS. 8 to 11  do of course also include suspension and drivetrain components (etc) as illustrated in  FIGS. 1 to 7 , but which are omitted for clarity. The two tubular members making up the tyre catcher in a V-formation allow a larger vertical area which caters for a wider range of suspension travel, catching the wheel regardless of the current vertical position of the suspension. In combination with the lateral and longitudinal alignment of the tyre catcher so as to meet the wheel as guided by the suspension and drive shaft elements that survive the impact, this ensures that the wheel can assist in absorbing impact forces as described above. Generally, in an impact the power train will move at the same time and thus the drive shafts will play a part in guiding the wheel. 
         [0040]    Finally,  FIG. 12  shows a variant on the example of  FIG. 4 . In this variant, the tyre catcher end cap or plate  109 ′ also becomes a deflector. Thus, the end cap  109 ′ is angled, being closer to the vehicle centreline at an edge closer to the wheel, and further from the centreline at an edge more remote from the wheel. As a result, under collision the tyre engages to the plate and is guided/deflected outward relative to the vehicle body. In the case of a rear wheel of an electrically-powered vehicle, this takes the wheel away from the battery storage area, and for an internal-combustion-engine vehicle takes the wheel away from the fuel tank and associated components. This arrangement can also be used on the front tyre catcher, in which case the tyre is deflected away from the cabin, assisting in preventing intrusion into the cabin. Importantly, the impact forces still run down the main longitudinal chassis rail  102  in the same way as the above-described embodiments. 
         [0041]    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. In particular, all of the examples shown can be applied to the front wheel or to the rear wheel or to both. Whilst the examples have been illustrated and described on one side of the car, there will usually be a symmetric arrangement on the other side of the vehicle.