Abstract:
An amphibious vehicle for transiting deep or shallow waters and/or the full range of wetland and dry soil environments, consists of a box-like structure with buoyant tracks that are powered to move around the structure. The buoyant tracks encircle the vehicle&#39;s length and extend laterally for a substantial portion of the vehicle&#39;s width or beam. When operating in water the buoyant tracks provide a majority of the buoyancy keeping the box-like structure above water surface or its tracks can be flooded to submerge the vessel. The amphibious vehicle can transport heavy equipment and personnel from ships located offshore, across undeveloped beaches, to positions ashore.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/852,422 filed Oct. 18, 2006, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    This present invention relates to an amphibious tracked vehicle which can operate in water and on land. 
         [0003]    Military and commercial operations in undeveloped regions often require the ability to transport equipment and personnel in an environment where soft soil, wetlands and water preclude the use of traditional vehicles. Often these operations require the transport of heavy equipment and personnel from ships offshore to locations ashore in areas where developed port facilities are either non-existent or are not available for use. And in certain operations the delivery of war material requires stealthy operations. 
         [0004]    Helicopters and amphibious transporters of current design are useful but lack the ability to carry particularly heavy pieces of equipment and are not necessarily stealthy. Tracked and large low-pressure tire land transportation vehicles are common and in wide use on solid soil, but are unable to operate in water or soils with low cohesive or shear strength properties. Currently available amphibious transporters also may be unable to traverse the soft soil beach interface between the ocean and the shore. 
         [0005]    All previous embodiments of amphibious vehicles utilize a fixed structure or hull to provide the majority of the buoyancy and tracks or wheels with a relatively small ground footprint area. This results in high footprint pressures for the propulsion system. 
         [0006]    Other amphibious vehicles that utilize buoyant tracks, as described in U.K. Patent Application No. GB 2351707; U.S. Pat. No. 6,582,258; and U.S. Patent Publication 2004/0239102, are configured with payload and machinery spaces positioned between or above the tracks. These vehicles do not allow the tracks to extend the full width of the vehicle and this results in deeper drafts when waterborne, and higher ground footprint pressures. Additionally access to payload and machinery spaces is problematic. 
       OBJECTS OF THE INVENTION 
     Brief Description of the Invention 
       [0007]    It is an object of the present invention to provide an amphibious vehicle capable of delivery payloads while propelled on land, on the sea surface or in a submerged condition. 
         [0008]    Another object of the present invention is to provide a vehicle for delivery of heavy payloads over soft soils, wetlands and water. 
         [0009]    Yet another object of the present invention is to provide a payload delivery vehicle in which the propulsion is provided in water and on the ground by the same propulsion system. 
         [0010]    A further object of the present invention is to provide a payload delivery vehicle having a tracked propulsion system wherein the tracks provide motive power on and under the sea surface and on land. 
         [0011]    A still further object of the present invention is to provide a tracked payload delivery vehicle in which the track system provides both motive power, on both land and sea, as well as buoyancy control. 
         [0012]    In accordance with an aspect of the present invention an amphibious vehicle consists of a core box-like structure in which there are areas for the carriage of heavy equipment, personnel, propulsion and control machinery, command and control systems for the vehicle, and structure for the installation of buoyant tracks. 
         [0013]    In accordance with another aspect of the invention the propulsion of such vehicles is derived from the motion of a belt or chain to which is affixed a number of tread or track bodies intended to achieve traction with surface water and/or the substrate or ground. The tread bodies are preferably buoyant structures that provide ground traction, as well as buoyancy and propulsion to the vehicle when it is waterborne. These track bodies occupy the majority of the width of the vehicle to produce low ground footprint pressures. The combination of a tracked vehicle and very large buoyant tracks to achieve buoyancy and traction with very low ground footprint pressure, enable the transport of large loads across water, land, and the wetland interface. 
         [0014]    The buoyant tracks used in accordance with the invention encircle the vehicle&#39;s length and extend laterally for a substantial portion of the vehicles width or beam. The buoyant track&#39;s construction may be a singular buoyant drive track or it may be formed in multiple parts consisting of the drive track and buoyant attachments. Track buoyancy may be provided by several means including pneumatic, low density solids or foam, or a combination of buoyancy means. Buoyancy means may be contained in singular or segmented structures that are integral to or attached to the drive track. Means of powering the drive track are well known in the art of tracked vehicle propulsion. 
         [0015]    The above and other objects, features and advantages of the present invention could be apparent to those skilled in the art from the following detailed description of an illustrative embodiment thereof when read in connection with the accompanying drawing, wherein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is an isometric view of an amphibious vehicle constructed in accordance with the present invention; 
           [0017]      FIG. 2  is a perspective view similar to  FIG. 1  with the vehicle&#39;s payload doors opened; 
           [0018]      FIG. 3  is a side view of the vehicle shown in  FIG. 1 ; 
           [0019]      FIG. 4  is a front end view of the vehicle shown in  FIG. 1 ; and 
           [0020]      FIG. 5  is a side view similar to  FIG. 3 , but with the side wall of the vehicle removed to show the various internal components of the vehicle; and 
           [0021]      FIG. 6  is a cross sectional view taken along line  6 - 6  of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Referring now to the drawings in detail, and initially to  FIG. 1 , an amphibious vehicle  10 , constructed in accordance with the present invention is illustrated. The vehicle consists of a body or shell-like frame  12  forming an enclosure for the vehicle and a pair of propulsion tracks  14  on opposite sides of the vehicle. As described hereinafter the housing  12  provides a preferably watertight enclosure containing a payload space and compartments for machinery and passengers. The tracks  14  are formed in any convenient manner to provide buoyant lift to the vehicle while providing tank-like traction for the vehicle while on the ground. In addition, the tracks are segmented and will also provide propulsion for the vehicle when floating on the service of the water. 
         [0023]    As illustrated in  FIG. 1 , the shell or body  12  includes an elongated payload door  16  which will also serve as an unloading ramp, as shown in  FIG. 2 . A door  16  may be provided on either side of the vehicle. Where the vehicle is intended to be submersible the door/ramp  16  will be provided with a conventional watertight seal arrangement so that the internal payload compartment, and other compartments within the vehicle, will remain watertight. 
         [0024]    The tracks  14 , as described hereinafter, extend through the upper portion of the shell above the interior compartment enclosed by the doors  16 . The shell provides passenger and/or machinery compartments  18 ,  20  in the fore and aft ends of the vehicle adjacent the payload compartment. These spaces are accessed by doors  22 , which also would be watertight. Additional access doors  24  may also be provided for access to machinery compartments. 
         [0025]    Because the vehicle is intended to carry large and heavy payloads, such as for example, tanks artillery and the like, the vehicle&#39;s height will be relatively substantial to accommodate that payload. Accordingly, ladders  26  are mounted on the side walls of the body or shell  12  to provide access to the doors  22 . 
         [0026]    As noted above, the door  16  when open will provide a discharge ramp for the payload contained within the vehicle. As seen  FIG. 2 , the ramp  16  and a corresponding ramp  16 ′ on the opposite side of the vehicle, are illustrated in their unloading position. The ramps are pivotally secured to the body or shell  12  in any convenient or known manner as would be apparent to those skilled in the art. Likewise, the watertight sealing arrangement, if required for the particular application in which the vehicle will be used, would be of conventional construction as would be apparent to those skilled in the art. 
         [0027]    As seen in  FIG. 2 , the body or shell  12  includes an interior payload compartment  28  including a deck  30 , front and rear walls  32  (only the rear wall of which is seen in  FIG. 2 ) all of which are preferably joined together by watertight arrangements. Thus the vehicle, when landed, will be able to rapidly unload the payload from the compartment  28 . 
         [0028]    In addition to the payload compartment  28 , the front and rear walls  32  of that compartment define utility spaces  34  at the fore and aft ends of the vehicle. These compartments provide space for personnel being transported and lead to central command and control centers  36  at the front and rear of the vehicle. As illustrated in  FIG. 5 , the compartments  34  may contain the power plant  40  for the vehicle, which is preferably a diesel engine or engines, connected to a motor/speed reducer  42 . The speed reducer is connected to a drive gear  44  located within a sealed compartment in the space  34  where it engages the track  14 . 
         [0029]    The tracks  14  are configured to engage the teeth on the sprockets  44  that so the tracks rotate along an oval path of travel, as seen  FIG. 5 . The track can include an integral link chain or ribbed belt for this purpose. The oval path of travel for the tracks is defined by the deck  30 , the ceiling  46  of the payload space  28 , and end walls  50  at the fore and aft ends of the spaces  34  and the bottom of deck  28 . Preferably a plurality of rollers  52  are mounted on the exterior of these surfaces for guiding movement of the track along its path of travel. 
         [0030]    The tracks  14  can be formed in any convenient manner. For example, they may be formed as an elongated belt on which a plurality of buoyant chambers  60  are pivotally mounted in any convenient or known manner. These chambers which are preferable formed of a flexible compliant material can be located between separate tread members  62 , which overlie the chambers thereby to provide a substantially continuous, albeit segmented, surface for the track. In addition, these tread segments will provide surfaces  54  that give traction to the track when it is engaged on the ground or which act as propulsion surfaces when the vehicle is operating on the surface of the water. By this arrangement the track will provide a shock absorbing function when the vehicle arrives on a beach and will flex to accommodate variations in terrain. 
         [0031]    Where the vehicle is intended for use solely as an amphibious vehicle, the chambers  60  of the track  14  can be air inflated or contain buoyant material to support the entire vehicle and its payload on the surface of the water. As the treads move through the water, the surfaces  54  of the tread segments  62  act as paddles propelling the vehicle in the appropriate direction. Steering is accomplished by varying the speeds of rotation of the respective tracks  14 . Additionally, a rudder mechanism can of course be provided. 
         [0032]    When the vehicle is intended to operate as a submersible, the chambers  60  of the treads  14  can be provided with buoyancy control systems which allow the chambers to be totally or partially flooded, thereby to submerge the vehicle. Alternatively, the payload compartment  28  may have ballast tanks mounted therein. In either case the vehicle can then operate beneath the surface of the water using a vertical periscope exhaust for the power plant, or under battery power for a stealthy approach a beach for discharge of the payload. The tracks  14  will operate on the sea floor, in the same way they would operate on the beach. 
         [0033]    Obviously, such tracks would be formed of appropriate materials to resist damage from the sea bed. As seen in  FIGS. 4 and 6 , the tracks  14  extend across the majority of the width of the vehicle. In their upper flight or path of travel the tracks are protected by the side walls  18  of the shell or hull  12 . Along their lower path of travel they are partially protected by those side walls. 
         [0034]    Because of the very large the width of the tracks relative to the vehicle, which width can occupy eighty to ninety percent or more of the width of the vehicle, they are able to both achieve buoyancy and traction over soft wet ground. In addition, as the buoyant track system enters the unloading zone and is propelled onto the beach, the buoyant tracks behave as a shock absorber as well as a complaint track accommodating surface variations. The track further provides a cushioning effect to soften the landing process in plunging surf conditions. 
         [0035]    Another advantage of the present invention is that the buoyant track amphibious transporter disclosed herein is readily scalable and can be sized to fulfill a variety of amphibious transport needs. As noted above, the payload bay and/or the buoyancy tracks can be augmented with variable ballast buoyancy control to permit an underwater operating mode for low observable or stealthy needs. 
         [0036]    While the principal means of propulsion described herein is through the track arrangement, it is to be understood that this propulsion mode can be augmented by other propulsion means attached to the main structure such as, propellers, thrusters, water jets, paddles or other known means for water propulsion. 
         [0037]    While the present invention has described herein with reference to particular embodiment shown in the drawings, it is to be understood that various changes and modifications may be effected therein by those skilled in the art without departing from the scope or spirit of this invention.