Abstract:
Amphibious vehicle having road wheels which are retractable to allow planing. Each wheel suspension is protractable through a gap in the planing surface of the hull. To reduce hydrodynamics drag and improve marine handling, covers are provided which cover such gaps when the wheels are retracted. These covers may be hinged parallel to a longitudinal, or to a transverse, axis of the vehicle or may be otherwise connected to the hull.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Great Britain Application Serial No. 0423470.4, filed Oct. 22, 2004.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to amphibious vehicles, and particularly to hull fairings for recesses in the hull.  
         [0003]     In our co-pending Patent Application No. PCT/GB/04/002156, a planing amphibious vehicle hull is shown with recesses in the areas where retractable wheels and their suspensions move during suspension retraction and protraction. Because the suspensions are assembled from below during manufacture, the recesses intrude considerably into the planing surfaces of the hull. In order to reduce this intrusion, plates are fixed across part of each recess after assembly of the suspension. These plates are currently glued into position, although they could be bolted. As will be seen from  FIG. 1  of the above prior application, it is clear that particularly the front wheel recesses are very much open at the bottom. As a result of the openings in the bottom of the hull, there can be problems with drag on the hull when the vehicle tramps through rough water. This is particularly problematic for vehicles smaller and lighter than that shown in the prior application.  
         [0004]     A further known solution to this problem of reducing drag on water is disclosed in U.S. Pat. No. 4,958,584, to Williamson. In this patent, a single sliding cover 18 (FIG. 5) for front and back wheel wells 42 on one side of the vehicle is powered fore and aft by a double acting hydraulic cylinder 148. This arrangement appears to be a very simple and elegant solution, but has considerable practical drawbacks.  
         [0005]     First, the slide channels will be susceptible to damage or seizure due to ingress of sand or silt. Second, the cover runs parallel to the hull for most of its length; so any grounding or collision damage which distorts either the hull or the cover would be liable to cause the two parts to jam together, preventing protraction of the wheels and stranding the vehicle on water.  
         [0006]     Third, the use of a single actuator to move such a large and complex sliding panel is liable to lead at the least to uneven panel movement, and at the most to complete seizure, especially as wear and play build up as the vehicle ages. Finally, a single cover as shown, which overlaps the hull between front and rear arches even when closed, would project below the hull at the front, at least, of each wheel arch, disturbing the smooth flow of water along the vehicle&#39;s planing surface. Clearly, fresh thinking is needed.  
         [0007]     An object of the invention is, therefore, to further reduce drag on an amphibious vehicle when in water.  
       SUMMARY OF THE INVENTION  
       [0008]     According to the invention, there is provided an amphibious vehicle having retractable road wheels each mounted by means of a wheel suspension to a vehicle body, the body having a planing bottom, wherein the bottom has for each suspension an interruption in the bottom through which at least a part of the suspension can move during retraction or protraction of its said road wheel, characterised in that the interruption is arranged to be substantially covered by a cover which is engaged by the part of the wheel suspension during wheel protraction so that the cover at least partially opens on wheel protraction.  
         [0009]     The fixture of the cover to the body of the vehicle may be hinged by means of a hinge or hinges, with hinge axes parallel to either the vehicle&#39;s longitudinal axis, or to its transverse axis. Alternatively, the cover may be movably arranged on a suitable linkage.  
         [0010]     In a preferred arrangement, the cover is connected to a lower suspension member, so that when protracting the wheels, the lower suspension member carries the cover down with it. The linkage between the suspension member and cover may be extensible, so that when retracting the wheels, the suspension member may retract into the interruption in the hull; while the cover is constrained to remain flush with the hull surface.  
         [0011]     The covers may be hollow bodies, which provide buoyancy to the vehicle on water. In this case, the covers may be made of blow moulded plastic. Alternatively, they may have buoyancy foam attached. The covers may also be profiled to match the hull planing surface, with features like strakes continued across the cover surfaces.  
         [0012]     These and other features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments which, taken in conjunction with the accompanying drawings, illustrate by way of example the principles of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a diagrammatic side elevation view of an amphibious vehicle according to the invention;  
         [0014]      FIG. 2  is a transverse cross section through plane II-II of the vehicle of  FIG. 1  according to a first embodiment of the invention, with the wheels retracted;  
         [0015]      FIG. 3  is a transverse cross section through plane II-II of the vehicle of  FIG. 1  according to a first embodiment of the invention, with the wheels protracted;  
         [0016]      FIG. 4  is a view from below the vehicle of  FIG. 1  with the wheels retracted;  
         [0017]      FIG. 5  is a transverse cross section through plane II-II of the vehicle of  FIG. 1  according to a second embodiment of the invention, with the wheels retracted;  
         [0018]      FIG. 6  is a view from below the vehicle of the second embodiment with the wheels retracted;  
         [0019]      FIG. 7  is a transverse cross section through plane II-II of the vehicle of  FIG. 1  according to a third embodiment of the invention, also with the wheels retracted;  
         [0020]      FIG. 8  is a perspective view of an amphibious vehicle having an opening in the hull underside and means for closing the opening in accordance with a fourth embodiment of the present invention;  
         [0021]      FIG. 9  is a side elevation of the closing means of  FIG. 8  showing the lower suspension arm penetrating the opening; and  
         [0022]      FIG. 10  is a side elevation view similar to that of  FIG. 9  showing a modified closing means. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     Amphibious vehicle  2  has a prime mover  4  driving a pump jet  6  through a marine transmission. Locomotion on road is provided by wheels  8 , which are driven through a road transmission. The wheels are shielded by wheel arches  12 . The vehicle body comprises an upper body  14  and a hull  16 , which are formed separately and joined at split line  18 . A chassis is also provided, as is described below. If this chassis is bonded to the bodywork, it may be regarded as part of the overall body structure. The hull has a planing surface  20 . A driver&#39;s seat  22  is provided with one or more passenger seats  24  astern of the driver&#39;s seat. The seating axis is on the longitudinal axis of the vehicle, or parallel thereto. The axis of the prime mover is also along, or parallel to, the longitudinal axis of the vehicle. Driver controls are provided, in this case handlebars  26 . A windscreen  28  is provided for weather and spray protection.  
         [0024]      FIGS. 2 and 3  show a pair of rear wheels  8  mounted on hubs  54 . The hubs are driven by intermediate shafts  62  and layshafts  60 , which are driven from the prime mover  4 . The intermediate shafts are supported inside lower suspension members  40  respectively which are each in the form of a tube. The tubelike members  40  are pivotally mounted at their inner ends on bearings  42 . The outer ends of members  40  are connected to upright members  52 , which carry hubs  54 . Upper suspension members  56  connect between vehicle chassis  30  and upright members  52 .  
         [0025]     As can be seen in  FIG. 4 , hull  16  has a planing bottom  20 , in which there are gaps  80  (which are apertures leading to slots formed in the vehicle body) forming interruptions in the bottom through which lower suspension members  40  can move, from a retracted position of the wheels as shown in  FIG. 2 , to a protracted or wheels down position as shown in  FIG. 3 .  
         [0026]     Fixed to lower suspension members  40  are covers  34 , which are fixed by means of inner and outer brackets  36  and  38  ( FIG. 3 ) to members  40 , so that the covers pivot about bearings  42 . The gaps  80  are defined by body edges  84 ,  86 , and  88 . Covers  34  when closed substantially fill gaps  80 , only leaving small clearance gaps  90  necessitated by the need to distance the outer faces of the covers from the centres of bearings  42 .  
         [0027]     In order to achieve complete filling of clearance gaps  90 , a second embodiment has a pair of covers  92  and  94  for each interruption in the hull surface, which are hinged at  96  and  98  on one side and at  100  and  102  on the other side of the planing surface  20 . This is shown in  FIGS. 5 and 6 . Door  92  is shown figuratively in an open position here, although the suspension is retracted; on the right hand side of the Figure, a dashed outline of the corresponding door is shown.  
         [0028]     Each cover  92 ,  94  of each pair hinges about a transverse axis of the vehicle so as to fill half of each gap  80 . The covers are split into pairs in “barn door” style to reduce downward protrusion below the hull surface  20  when the covers are open. The covers may be made flexible to avoid breakage on striking rocks, etc. They may also protect the wheel suspensions from impact damage, e.g. scratching of anti-corrosive coatings. The simplest and most foolproof means of opening these covers is to arrange for them to be held shut by springs  110  and  112  ( FIG. 5 ) when wheels are retracted, and pushed open by the suspension as the wheels protract. Alternatively, mechanical linkages to the wheel suspensions may be arranged. Such linkages could be designed to impart a translating movement to the covers, so that they move transversely across the vehicle before or during deployment.  
         [0029]     It may be found that the travel of hull gap covers attached to suspension members is preferred to be less than that of the retractable suspension. Particularly where a narrow hull is combined with a large vee angle, as seen in the Figures, it will be necessary for the wheels to be tipped up at a large angle to the road position to keep them above the water line when cornering on water. In this case, if the covers are constrained to move through the same angles as the lower suspension members, covers which are flush with the hull when the wheels are retracted may hit the ground when the wheels are protracted; conversely, covers which as shown in  FIG. 3 , clear the ground adequately in road mode, will be drawn up above the hull line when the wheels are retracted.  
         [0030]     This mechanical contradiction may be averted by breaking the fixed mechanical link between the covers and the suspension members.  FIG. 7  shows such an arrangement with the wheels retracted. Cover  180  on the right hand side of the Figure (left hand side of the vehicle) is shown retracted, as it would be with the wheels retracted; but cover  180  on the left hand side of the Figure (right hand side of the vehicle) is shown figuratively in a protracted position, to show linkage  182 .  
         [0031]     When the suspension is protracted, covers  180  are pushed down below planing surface  20  by stops  194  mounted on the lower suspension members. In this position, covers  180  are stabilized by linkages  182 . When the suspension is retracted, pins  194  also retract; and covers  180  are pulled up towards surface  20  by tension springs  192 , which are tethered above surface  20 . The suspension members will be pulled up inside the hull as far as is required to fully retract the wheels; but the covers will be held in place flush against the hull by tabs  104 , which are moulded into the hull for this purpose. Alternatively, tabs  104  may be moulded into the covers. Linkages  182  collapse for storage, as shown on the right hand side of the Figure.  
         [0032]     The arrangement of  FIG. 7  could be modified by replacing cover  180  with a pair of “barn door” covers as shown in  FIG. 6 , each of the doors being biased closed by a spring, both being engaged by the lower suspension arm  40  (or a pin  194  attached thereto) and both being biased against a stop formed either by a tab extending from the hull or by tabs extending from the covers. The “barn door” covers of this arrangement (or indeed the arrangement of  FIG. 7 ) could be replaced by a single cover hinged at its leading edge (i.e. its edge nearest the front of the vehicle) by a hinge extending transversely of the vehicle; in this way in marine operation the force of water will help keep the cover closed.  
         [0033]      FIGS. 8 and 9  show a means for closing the slots in the vehicle hull when the wheels are retracted. The slot closing means comprises a cover plate  216  attached to the inside of the hull underside and which is arranged to cover the slot. The cover plate  216  can be attached to the hull by any suitable means such as spot welding, seam welding, riveting or by adhesive. The cover plate  216  in the preferred embodiment is attached to the hull adjacent the fore and aft edges of the slot respectively.  
         [0034]     The cover plate  216  is contoured, so that the area of the plate above the slot itself lies in a plane slightly inboard of the inner surface of the hull underside to provide a recess  219 . The cover plate  216  is provided with an opening  220  which is shaped to provide a small working clearance for the lower suspension arm  40 . (In the embodiment, arm  40  takes the form of a driveshaft which is connected to a suspension upright  52 ).  
         [0035]     A resilient cover  222  is attached to the outboard side of the cover plate  216  adjacent to the forward edge of the slot. The cover  222  may be attached to the cover plate by any suitable means. In the embodiment shown, the cover  222  is attached to the cover plate by means of four screws  223  which engage with corresponding nuts  224  on the inner surface of the cover plate. The heads of the screws  223  are countersunk into the cover so that they lie generally flush with the outer surface of the cover.  
         [0036]     The cover  222  may be made of rubber, synthetic rubber or any other suitable material. As indicated above, the cover is resilient and the material and the dimensions of the cover are selected to ensure that the cover has a natural tendency to move to the closed position  222   a  as indicated by the dashed lines in  FIG. 9 . In  FIG. 9  it is illustrated that it is the lower suspension arm  40  which passes through aperture  220  and not the upright  52 .  
         [0037]     The thickness of the cover and the recess  219  in the cover plate  216  are arranged so that when the cover  222  is in the fully closed position  222   a , the outer surface  25  of the cover is substantially flush with and forms a generally continuous surface with the outer surface of the hull underside.  
         [0038]     Attached to the lower suspension arm  40  is a peg  228  which defects the cover  222  downwards from its closed position  222   a  as the wheel moves to the protracted position for land use. The peg  228  holds the cover clear of the lower suspension arm while the wheel is protracted.  
         [0039]     Operation of the cover will now be described.  
         [0040]     When the wheel and suspension member are moved to a protracted position, the peg  228  contacts the cover  222  and deflects it downwardly, as shown at  222   b  in  FIG. 9 , holding the cover clear of the lower suspension arm. In this position the vehicle is adapted for land use and the lower suspension arm projects through the slot and the opening  220  in the cover plate  216 .  
         [0041]     When the vehicle is in sufficient depth of water, the wheels can be retracted for waterborne use. As the wheels retract, the lower suspension arm  40  pivots up through the slot and the opening  220  so as to lie inboard. At the same time the resilience in the cover  222  biases the cover towards its closed position  222   a  within the recess  219 . At this stage, water will be present both above and below the cover so that the cover may not fully close initially. However, increasing speed of the vehicle in the water will raise the water pressure on the underside of the cover  222  pressing it into the recess  219  to complete the closure process. It will be apparent that when the cover is in the fully closed position  222   a , the cover substantially fills the slot to provide a generally smooth and continuous hull surface.  
         [0042]     A modification to the cover arrangement is shown in  FIG. 10 , in which a spring  232  has been added to the cover  222  to ensure that the cover is resiliently biased to the closed position  222   a . Such a spring may be required where the natural resilience of the cover material is insufficient to return the cover to the closed position without assistance.  
         [0043]     The spring  232  comprises a plate of spring stainless steel which is attached to the inner surface of the cover  222 . The spring  232  is fastened to the rearward end of the cover by means of rivets  233  which pass through corresponding holes in the spring  232  and the cover  222 . These holes may be oval or oversized round holes to accommodate assembly tolerances, and/or relative movement in service. Washers  234  are provided on the cover side and the spring side to spread the clamping load of the rivets.  
         [0044]     The cover  222  and plate spring  232  effectively form a composite cover which is received within the recess  219  when the cover is in the closed position  222   a , the depth of the recess  219  being selected such that the outer surface  225  of the cover  222  is flush with the outer surface of the hull underside.  
         [0045]     Other forms of spring could also be used to bias the cover  222  towards the closed position. For example coil springs or multi-leaf springs could be used. However, it is considered that a spring made of a plate or strip of stainless steel would be less susceptible to corrosion damage in the salt water environment in which it is required to operate.  
         [0046]     While a particular form of the present invention has been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without departing from the spirit and the scope of the present invention. For example, the covers described may be applied to a non-driven, and/or a steered, axle. Rather than the lower suspension members being tubular, they may be solid, or wishbones. Accordingly, it is not appended claims.