Abstract:
A sit-stride amphibious vehicle configuration which supports a high performance envelope both on land as well as in water. The vehicle has a planing hull and four retractable wheels. Handlebars provide for directional control in both modes of operation. Each road wheel is retractable by pivoting through at least 45° so as to maximize ground clearance when in the land mode of operation and to minimize drag at substantial lean angles when in the marine mode of operation. While a jet drive may remain directly connected to the engine at all times, the drive wheels are only connected during land mode via a speed-change transmission. The entire power train is supported by a frame that is separable from the hull which in turn has a detachable top deck portion, whereby such configuration simplifies the construction, repair and servicing of the vehicle.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Great Britain Application Serial Nos. 0423463.9, 0423470.4, 0423474.6, 0423483.7 and 0423517.2, all filed Oct. 22, 2004.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an amphibious vehicle and in particular, to a sit-astride amphibious vehicle having all-terrain vehicle (ATV) capability on land.  
         [0003]     Amphibious vehicles are now well known in the art. However, the present applicant has identified a need for an amphibious vehicle having ATV capability on land and which performs as a high speed personal watercraft on water. A number of prior art proposals have proceeded to prototype. However, such vehicles have opted to either optimise operation in the marine mode or, alternatively, operation in the land mode. The result is an amphibious vehicle having poor performance in one mode of operation or the other.  
         [0004]     Sit astride amphibious vehicles have previously been described such as in U.S. Pat. No. 5,690,046 to Grzech. Grzech teaches an amphibious tricycle. The problem identified by the inventor in this document, was to provide his personal watercraft (PWC) with limited on land capability in order that it was at least partially mobile when going ashore. GRZECH is limited in that it is only suitable for travel on well made up roads when operating in a land mode. This is because the vehicle has only three wheels and these are connected to the remainder of the vehicle by a suspension arrangement which is adapted to cope only with smooth road surfaces and does not have the suspension travel suitable for off-road use of the vehicle. Also, GRZECH needs a large heat exchanger which protrudes through the keel of the vehicle to provide the very necessary cooling required to cool the highly overpowered marine combustion engine. This dictates against off-road land use since the heat exchanger could easily be damaged in such a use. GRZECH has opted for a single steerable front wheel since this is easiest to provide in an adaptation of a personal watercraft.  
         [0005]     Accordingly, there exists the need for an all terrain high speed amphibian vehicle, more particularly, having at least four retractable wheel assemblies.  
       SUMMARY OF THE INVENTION  
       [0006]     In a first aspect, the present invention provides an amphibious vehicle comprising:  
         [0007]     a sit-astride seat,  
         [0008]     a planing hull,  
         [0009]     at least four wheels, each of which is movable between an extended land mode location and a retracted water mode location, two of the wheels being front steerable wheels, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0010]     an engine which in the land mode of the vehicle is connected to at least one of the wheels to drive the wheel, and  
         [0011]     marine propulsion means to propel the vehicle on water.  
         [0012]     GRZECH only seeks to provide a PWC with a limited on-land function; he has taken an existing PWC and adapted it with few changes. GRZECH teaches that the engine can be connected to the driven wheels through a transmission with one fixed gear ratio.  
         [0013]     In a second aspect the present invention provides an amphibious vehicle comprising:  
         [0014]     a sit-astride seat  
         [0015]     a planing hull,  
         [0016]     at least four wheels, each of which is movable between an extended land mode location and a retracted water mode location, at least two of the wheels being front steerable wheels, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0017]     an engine which in the land mode of the vehicle is connected to at least one of the wheels to drive the wheel, and  
         [0018]     marine propulsion means to propel the vehicle on water.  
         [0019]     GRZECH in adapting a PWC has sought to keep the overall dimensions of the vehicle within those of an existing PWC; thus he has chosen rear wheels on a trailing arm suspension with a track width less than the hull beam and also a single retractable front wheel.  
         [0020]     In a third aspect the present invention provides an amphibious vehicle comprising:  
         [0021]     a sit-astride seat,  
         [0022]     a planing hull,  
         [0023]     at least four wheels, all of which are movable between an extended land mode location and a retracted water mode location, each being pivoted about an axis running fore and aft along the vehicle when moved between the land mode and the water mode locations thereof, two of the wheels being front steerable wheels, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0024]     an engine which in the land mode of the vehicle is connected to at least one of the wheels to drive the wheel, and  
         [0025]     marine propulsion means to propel the vehicle on water.  
         [0026]     In a fourth aspect the present invention provides an amphibious vehicle comprising:  
         [0027]     a sit-astride seat,  
         [0028]     a planing hull,  
         [0029]     at least four wheels, each of which is movable between an extended land mode location and a retracted water mode location, two of the wheels being front steerable wheels, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0030]     an engine which in the land mode of the vehicle is connected to at least one of the wheels to drive the wheel, and  
         [0031]     marine propulsion means to propel the vehicle on water, wherein:  
         [0032]     the planing hull is formed as a single component and the vehicle has one or more deck components all joined to the hull component along a join line which extends around an entire periphery of the vehicle at a level above a water line of the vehicle in water; and  
         [0033]     the or at least one of the deck components forms a majority of an upwardly facing surface of the vehicle and is demountable to allow access to the engine located there beneath.  
         [0034]     In a fifth aspect the present invention provides an amphibious vehicle comprising:  
         [0035]     a sit-astride seat,  
         [0036]     a planing hull,  
         [0037]     at least four wheels, each of which is movable between an extended land mode location and a retracted water mode location, two of the wheels being front steerable wheels of the vehicle, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0038]     an engine which in the land mode of the vehicle is connected to at least one wheel to drive the wheel, and  
         [0039]     marine propulsion means to propel the vehicle on water, wherein:  
         [0040]     the engine is mounted on a frame releasably connected to the hull, the vehicle also comprising a transmission connecting the engine to the driven wheel(s), at least part of the transmission also being mounted on the frame.  
         [0041]     In a sixth aspect the present invention provides an amphibious vehicle comprising:  
         [0042]     a sit-astride seat,  
         [0043]     a vehicle body having a planing hull,  
         [0044]     at least four wheels, each of which is movable between an extended land mode location and a retracted water mode location, two of the wheels being steerable wheels, which are, at least in the land mode of the vehicle, connected to handlebars which can be operated by a driver to steer the vehicle,  
         [0045]     an engine which in the land mode of the vehicle is connected to at least one of the wheels to drive the wheel, and  
         [0046]     marine propulsion means to propel the vehicle on water, wherein:  
         [0047]     the vehicle body defines a pair of footwell areas spaced apart on both sides of the sit-astride seat with the vehicle body having sill portions positioned laterally outside the footwell areas.  
         [0048]     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  
       [0049]      FIG. 1  is a perspective view from above of an amphibious vehicle according to the present invention;  
         [0050]      FIG. 2  is a perspective view from below of the amphibious vehicle of  FIG. 1 ;  
         [0051]      FIG. 3  is a top plan view of the amphibious vehicle of  FIG. 1 ;  
         [0052]      FIG. 4  is a bottom plan view of the amphibious vehicle of  FIG. 1 ;  
         [0053]      FIG. 5  is a side elevation view of the amphibious vehicle of  FIG. 1 ;  
         [0054]      FIG. 6  is a front elevation view of the amphibious vehicle according to  FIG. 1 ;  
         [0055]      FIG. 7  is a rear end elevation view of the amphibious vehicle of  FIG. 1 ;  
         [0056]      FIG. 8  is a view of the vehicle of  FIG. 1  in which the top surface of the vehicle has been made transparent;  
         [0057]      FIG. 9  is a perspective view of a steering and suspension assembly of the vehicle;  
         [0058]      FIG. 10  is a front elevation view of the steering and suspension assembly of  FIG. 9 , with the wheels in their lowered land mode operation location;  
         [0059]      FIG. 11  is the same front elevation view as  FIG. 10 , but with the wheels raised in marine mode operation;  
         [0060]      FIGS. 12-18  correspond to the views shown in  FIGS. 1-7  save that the views shown in FIGS.  13  to  18  show the amphibious vehicle with its wheel assemblies retracted for use in marine mode  
         [0061]      FIG. 19  is a perspective view of a rolling chassis of the vehicle; and  
         [0062]      FIG. 20  is a diagrammatic view of a transmission of the vehicle. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0063]     Referring now to  FIGS. 1 and 2 , there can be seen an amphibious vehicle  10  having a forward bow end  12  and a rear stem end  14 .  
         [0064]     The vehicle  10  has four road wheels  50 , 51 , 52 , 53  which are connected to the remainder of the vehicle by a wheel suspension system which includes a wheel retraction mechanism for moving the wheels  50 , 51 , 52 , 53  between a lowered state for road use and a raised state for marine use. The front wheels  50  and  53  are steerable and handlebars  54  enable steering of these wheels. The rear wheels  51 , 52  are driven to propel the vehicle on land. A jet drive unit  55  (see  FIG. 2 ) provides propulsion in marine use.  
         [0065]     The structure of the amphibious vehicle  10  comprises an upper deck section  30  and a lower hull section  40 . The upper deck structure  30  is sealed to the lower hull section  40  around a peripheral planar edge which is above the water line when the amphibious vehicle  10  is displaced in water—(as can best be seen in  FIG. 5  and  FIG. 8 ). The complete upper deck section  30  is detachable from the lower hull section  40  as a single unit; this permits ease of access to internal components of vehicle for servicing, etc.  
         [0066]     Air inlet openings  31  provide an entry for cooling air (e.g. fan-assisted) for use by the cooling systems of the amphibious vehicle  10 . Air entrained via inlets  31  is eventually exhausted via outlets  32 . Between air inlet  31  and air outlet  32 , a dorade system is installed to prevent the ingress of water. The dorade system facilitates righting of the vehicle on water by use of a labyrinthine air inlet passage system to prevent the ingress of water should the amphibious vehicle  10  be inverted in use in the marine mode. Sit-astride seats  33  and  34  are provided for a driver and a passenger of the amphibious vehicle  10 . A footwell area  35  is provided either side of the sit-astride seats  33 ,  34 , each shrouded by bodywork positioned laterally outside of the footwell area  35  to provide protection. These footwell areas  35  may be provided with means to bail automatically any water shipped in use of the amphibious vehicle  10 .  
         [0067]     Front and rear wheel arches  36 ,  37  are provided on either side of the amphibious vehicle  10  so as to contain a retractable wheel assembly which is retracted when the amphibious vehicle  10  is operating in the marine mode. An instrument panel  38  is provided ahead of the steering controls to convey relevant parameters of the amphibious vehicle  10  to the driver. Additionally, rear view mirrors (not shown) may be provided as a visual aid to the driver. Furthermore, navigation lights may also be provided within or on the upper deck structure  30  in accordance with the local legislative requirements.  
         [0068]     The upper deck structure  30  forms an integral part of the entire structure of the vehicle. It is a structural component and not merely cladding. Typically it will take the form of a composite structure (e.g. glass fibres or carbon fibres set in resin) although any suitable manufacturing method may be employed. Where localised areas of strength are required in the upper deck structure  30 , extra layers or mats of fibres may be laid down during manufacture. The deck  30  will be formed with localised reinforced areas in order to provide a complete force transmitting path extending around the vehicle in a complete circle in a plane orthogonal to a longitudinal axis of the vehicle, in order to provide resistance to torsional loads on the vehicle.  
         [0069]     Referring now to  FIGS. 2 and 4  the underside of the hull can be seen extending from the front bow section  12  to the rear stem section  14 . Starting from the planar interface with the upper deck section  30 , there is a relatively shallow section  41  extending around a periphery of the amphibious vehicle  30  and in this section there are provided front and rear wheel arches  42 ,  43 . These areas of the hull provide stability when the amphibious vehicle  10  is operated at high speed in marine mode because they provide enclosed volumes spaced laterally from the centre line of the amphibious vehicle  10 . As such, when cornering sharply, for example, an increase in righting force is experienced as the angle of lean increases. The bodywork lateral of the footwell areas could be provided with buoyancy inserts which would provide righting forces spaced from the vehicle centre line when the vehicle comers on water.  
         [0070]     Cutouts are provided in the hull on either side of the centre line of the vehicle in the region of the front and rear wheel arches  42 ,  43  to provide slots through which the retractable wheel assemblies can be protracted and retracted. Suitably profiled covers  44 ,  45  are provided as part of the wheel assemblies so as to reconstruct the lines of the hull when the wheel assemblies are retracted for use in marine mode.  
         [0071]     A lower V section  46  depends from the mid section  41  and is provided with a keel section running from the bow  12  of the amphibious vehicle to approximately halfway along the length of the vehicle. At this point, the keel splits to incorporate a water intake area  49  for a jet drive marine propulsion unit of the amphibious vehicle  10 . The design of the hull  40  is critical in determining the performance achieved when the amphibious vehicle  10  is operated in the marine mode.  
         [0072]     The present applicants have spent considerable time and effort in the design of the hull  40  which has resulted in a rather surprising shape in that usually expected for a planing water craft. The dead rise angle of the hull is substantially 20.7 degrees along substantially its entire length. This compares with traditional planing hulls which start at the bow section with a very steep dead rise angle and these dead rise angles become more shallow along the length of the hull towards the stem, typically ending at 5 degrees or less of dead rise angle.  
         [0073]     Since the seating of the vehicle is arranged longitudinally along the vehicle, the vehicle is narrower than a passenger car. Aligning the engine longitudinally along the vehicle gives a body shape which is narrow in beam and deep. Rather than adopting the flat planing hull common in the prior art, the applicant has adopted a greater dead rise angle for the agile marine handling this provides, accepting that this gives a need for a suspension with a lot of travel to give adequate ground clearance on land. Large wheels also enable off-road usage, although they give problems of packaging. Whereas before vehicles such as that of GRZECH strove to keep the track width of the wheels within the beam of the vehicle, the applicant has realised that better land mode operation can be achieved if the track width of the vehicle is greater than the beam of the hull. The approach adopted by the applicant does mean that wheels must be retracted through a large angle in order to be clear of the vehicle waterline in marine use, but the strategy does provide for a vehicle capable both on land and on water.  
         [0074]     The hull  40  is additionally provided with hydrodynamic aids in the form of strakes  47 ,  48  and the profiled suspension arm covers  44 ,  45  previously referred to. Even with the small footprint of the hull of the amphibious vehicle  10 , the hull design  40  is capable of propelling the amphibious vehicle  10  up onto the plane with little difficulty in fast time periods. Furthermore, on-water performance of the amphibious vehicle  10  is not compromised and adequate ground clearance is available in operating the amphibious vehicle  10  in land mode as an all terrain vehicle.  
         [0075]      FIG. 8  illustrates location of the major internal components of the amphibious vehicle  10 .  
         [0076]     In  FIG. 8  there can be seen a prime mover  60  which is a multi-cylinder internal combustion engine. It is connected by a transmission  61  to drive the rear wheels  51 , 52  during land use of the vehicle and to drive the jet drive unit  55  during marine use. As described in other applications of the applicant the jet drive unit is permanently connected to the engine  60  to be driven thereby at all times, whilst the wheels  51  and  52  are connected to the engine  52  only in their lowered land use positions.  
         [0077]     In  FIG. 8  it can be seen that the handlebars  54  are connected by a steering column  62  to a steering mechanism  63  for steering the front wheels  50 , 53  of the vehicle which is described in detail in another application of the applicant. Spring and damper assemblies  64 , 65 , 66 , 67  are provided in-board for the wheels  50 , 51 , 52 , 53 . Two wheel retraction hydraulic actuators (which cannot be seen in the Figure) are provided, one for the front wheels  50 , 53  and one for the rear wheels  51 , 52  to allow the wheels to be retracted from their lowered positions shown in  FIG. 8  to their raised positions. These hydraulic actuators will be powered by hydraulic fluid supplies from a pump (not shown) powered by the engine  60 .  
         [0078]     The seating in the vehicle is provided substantially above the vehicle powertrain, with the handlebars located roughly halfway along the length of the vehicle, this comparing with traditional PWC designs which locate the handlebars roughly two thirds along the length of the vehicle (measured from the back). This gives a good weight distribution for both marine and land use.  
         [0079]     The powertrain components illustrated in  FIG. 8 , i.e. the engine  60 , the transmission  61  are built up on a frame platform which is then connected to the hull; this gives considerable advantage for ease of manufacture. Indeed it is envisaged that a chassis could be constructed with a frame supporting all of the wheel suspension components, the wheel steering mechanism, the wheel retraction mechanism, the engine  60  and the transmission  61 . This would considerably aid construction and repair. This is illustrated in  FIG. 19  where a rolling chassis  300  of the vehicle can be seen stripped of the surrounding hull and deck sections. In the Figure there can be seen the engine, the transmission  61  as well as the suspension assemblies for the front and rear wheels and radiators  70 ,  302  of the cooling system of the vehicle, all mounted to a common supporting structure  303 .  
         [0080]     The radiator  70  can also be seen in  FIG. 8  located at the front of the vehicle which will cool the vehicle&#39;s engine, at least in land use. The vehicle&#39;s engine can also be cooled by a water/water heat exchanger (not shown) in marine use, with water being drawn from beneath the vehicle to cool water used by the engine cooling system.  
         [0081]     The transmission  61  comprises an output shaft  71  leading drive from the engine to a gearbox  72  which has two output shafts; a horizontally extending shaft  73  taking drive to the jet drive unit  55  and a vertically extending shaft  74  leading to a continuously variable transmission arrangement, the pulleys  75 , 76  of which can be seen in  FIG. 8  and which is shown schematically in  FIG. 20 . As shown in  FIG. 20 , the continuously variable transmission has a vertically extending output shaft  400  which extends downwardly to a differential  401  through which drive is relayed to the rear wheels  51 , 52 . The CVT transmission  61  could be replaced in other embodiments by a conventional automatic gearbox or a manual gearbox.  
         [0082]     FIGS.  9  to  11  show the front steering and suspension assemblies of the vehicle. A frame  101  has swingably mounted to it left and right suspensions  103  and  105  as seen from the rear of the vehicle.  
         [0083]     Each suspension  103  and  105  comprises an upright member  107  (see  FIG. 10 ) connected to a lower suspension arm  109  and an upper wishbone  111 . Wheels  50  and  53  (shown in  FIG. 1 ) are each mounted to a hub  114 , which is rotatably carried on upright member  107 .  
         [0084]     Extending from each of the upright members  107  is a steering arm  117  (see especially  FIG. 9 ) to which is pivotally connected a track rod extension  119  at its outer end  121 . The inner end of extension  119  is connected to a track rod  123 . The track rod  123  is moved transversely by means of link  125  which is connected to a swingable connection  127  on steering column  129 .  
         [0085]     An actuator  141  having piston rod  143  acts on one arm of swing arm  137  to pivot the arm, the outer ends of which are connected to piston rods  144  of suspension dampers  145  (see  FIGS. 10 and 11 ), which are surrounded by coil springs  146 . The base of each damper  145  is connected at  147  to retraction arm  149  pivotally mounted at  151  to frame  101 . On retraction the suspension swings about an axis running fore and aft longitudinally along the vehicle; a torsion tube  151  rotates and the lower suspension arm  109  rotates with it (compare  FIGS. 10 and 11 ).  
         [0086]     Whilst above a single internal combustion engine is used to both drive the wheels is land mode operations and also to power the jet drive, separate engines could be provided, one for the road wheels and another for the jet drive. Also the jet drive could be replaced by a propeller.  
         [0087]     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 scope of the present invention. Accordingly, it is not intended that the invention be limited except by the appended claims.