Abstract:
A human-powered land vehicle, such as a bicycle, is mountable to a collapsible water craft having a compact drive unit which can be pivoted about two orthogonal axes, one for directing the thrust for steering the craft, the other for raising or lowering the thrust assembly. The drive unit is releasably mountable to the frame of the vehicle and is connected in use to receive torque from the crank, for instance by an endless chain, and by a remote linkage to the handlebars, or like steering device of the vehicle.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to water craft supporting and driven by human-powered land vehicles, such as bicycles. 
       BACKGROUND OF THE INVENTION 
       [0002]    International Patent Publication WO 96/15026 describes a collapsible water craft comprising two floats joined by a structure to which a bicycle may be clamped and which enables the user to operate the craft in like manner to the way the bicycle is operated on land. A propeller assembly is connected to the front wheel and to a pivoting joint defining a generally vertical steering axis, allowing the propeller to be steered by the bicycle&#39;s handlebars. The propeller is driven, through a flexible shaft, by a roller pressed to contact the rear tyre. 
         [0003]    While the sealed propellor assembly itself is a compact unit, the additional pivoting joint supporting the assembly for steering adds significant bulk, increasing the space required when storing or transporting the craft in its collapsed state. Furthermore, there is a need to provide a hinge mounting for the propellor assembly such that, with the craft assembled ready for launching, the propellor can be swung up clear of the base of the floats to prevent it being damaged by contact with the ground. It would be advantageous if such a hinge would also allow the propellor to retract when driven into an obstruction. 
         [0004]    It is an object of the present invention to address the above needs, or more generally to provide an improved watercraft. 
       DISCLOSURE OF THE INVENTION 
       [0005]    According to one aspect of the present invention there is provided a water craft driven by a human-powered land vehicle having a crank rotated to drive the land vehicle, the craft comprising; 
         [0000]    at least one float;
 
supports for releasably securing the human powered vehicle to each float;
 
a drive unit having:
       a primary shaft mounted for rotation about a primary axis;   a housing;   a secondary shaft drivingly connected by a first gear set to the primary shaft, the secondary shaft being received in the housing and mounted for rotation about a secondary axis, and   a rotor drivingly connected to the secondary shaft to thrust water; whereby the housing is pivoted about the primary shaft axis for raising and lowering the rotor and about the secondary shaft axis for directing the thrust from the rotor;
 
the craft further including transmission means for transmitting drive torque from the crank to the primary shaft, and
 
steering means connected to the housing for transmitting a user&#39;s steering movement to pivoting of the housing about the secondary shaft axis.
       
 
         [0010]    The rotor may be mounted within the housing or externally of the housing. For instance, the rotor may be mounted on the secondary shaft within the housing. 
         [0011]    Alternatively, the drive unit further includes: 
         [0000]    a propeller shaft supported in bearings in the housing for rotation about a propeller shaft axis;
 
a second gear set drivingly connecting the secondary shaft to the propeller shaft, and
 
wherein the rotor is mounted on the propeller shaft externally of the housing.
 
         [0012]    Preferably the land vehicle includes steering apparatus for steering a wheel of the land vehicle and the steering means transmits steering movement from the steering apparatus to the housing. Alternatively, the steering means may comprise a handle fastened to the housing so as to allow the user to pivot the housing about the secondary axis. 
         [0013]    Preferably the at least one float is elongate, the primary shaft extends transversely relative to the float, and the secondary shaft extends substantially perpendicular to the primary shaft. 
         [0014]    Each gear set preferably includes a meshed pair of bevel gears. 
         [0015]    Preferably the transmission means includes a toothed sprocket fixed to the primary shaft and connected by an endless member to a toothed pulley fixed to the crank. The endless member may a chain or a toothed belt. 
         [0016]    The drive unit preferably further includes a mounting bracket fixed to the upper housing for releasably connecting the drive unit to the land vehicle, the mounting bracket having a tongue adapted to be received in a channel formed in a fitting fixed to the land vehicle, the channel extending substantially parallel to the axis of the crank for allowing the fixed position of the drive unit to be varied in the direction of the channel axis. 
         [0017]    According to another aspect of the present invention there is provided a collapsible water craft driven by a human-powered land vehicle having a crank for driving the land vehicle and steering apparatus for steering a wheel of the land vehicle, the craft comprising: 
         [0000]    at least one float;
 
supports for releasably securing the human powered vehicle to each float;
 
a drive unit having:
       a primary shaft mounted for rotation about a primary axis;   a housing;   a secondary shaft drivingly connected by a first gear set to the primary shaft, the secondary shaft being received in the housing and mounted for rotation about a secondary axis, and   a rotor drivingly connected to the secondary shaft to thrust water; whereby the housing is pivoted about the primary shaft axis for raising and lowering the rotor and about the secondary shaft axis for directing the thrust from the rotor;
 
the craft further including a toothed sprocket fixed to the primary shaft and connected by an endless member to a toothed pulley fixed to the crank
 
for transmitting drive torque from the crank to the primary shaft, and
 
steering means connected to the housing for transmitting steering movement from the steering apparatus to the housing.
       
 
         [0022]    This invention provides a water craft which is effective and efficient in operational use, and which by its modular construction allows a human-powered land vehicle to be readily adapted for use on water. The water craft may be economically constructed and collapses to a compact unit, particularly providing a compact drive unit providing both steering and hinging for the thrust assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: 
           [0024]      FIG. 1  is a side elevation of a preferred embodiment of the water craft of the invention (showing a bicycle fixed in position); 
           [0025]      FIG. 2  is a pictorial view of the water craft of  FIG. 1 ; 
           [0026]      FIG. 2   a  is an enlarged view of the connection of the inner ends of the steering cables to the drive unit; 
           [0027]      FIG. 2   b  is an enlarged view of the connection of the outer ends of the steering cables to the forks of the bicycle; 
           [0028]      FIG. 2   c  is an enlarged view of the connection of the outer ends of the cross members to the floats; 
           [0029]      FIG. 3  is an end view of the drive unit of the water craft of  FIG. 1 ; 
           [0030]      FIG. 4  is a section along line M of  FIG. 3 ; 
           [0031]      FIG. 4   a  is an enlargement of detail C of  FIG. 4 ; 
           [0032]      FIG. 5  is a side view of the drive unit of  FIG. 3 ; 
           [0033]      FIG. 6  is a section along line BB of  FIG. 5 ; 
           [0034]      FIG. 7  is a top view of the drive unit of  FIG. 3 ; 
           [0035]      FIG. 8  is a side view of the drive unit of  FIG. 3 ; 
           [0036]      FIG. 9  is a pictorial view of an alternative thrust assembly for the drive unit of  FIG. 3 , and 
           [0037]      FIG. 10  is a sectioned pictorial view of the thrust assembly of  FIG. 9 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    Referring to  FIG. 1  of the drawings, the water craft  1  of the invention, in the preferred embodiment illustrated, generally includes a pair of floats  2   a ,  2   b  (float  2   a  shown partially cut away for clarity) connected by supports  3  for a bicycle  4 , or another human-powered land vehicle. A drive unit  5  mounted to the bicycle  4  propels the water craft  1 , thrust being transmitted from the user&#39;s rotation of the pedal-operated crank  6  and steering from turning of the handlebars  7 . 
         [0039]    As shown in  FIG. 2 , the water craft  1  is collapsible for storage or transport, the floats  2  each being formed from an inflatable skin having tapered bow and stern portions  8 ,  9  joined by a generally tubular portion  10  to form a pocket which defines the shape of each hull when inflated. 
         [0040]    The floats  2  are joined by the supports  3 , which include front and rear cross-members  11 ,  16  having connectors  12  at each end for releasable connection to connectors  13  provided on the floats  2   a ,  2   b . An upright  14  is detachably fixed by joint  52   a  at one end to the centre of the cross member  11  and engages a mount  15   a  at the opposing end, the mount  15   a  being fixed, as by welding, to the frame of the bicycle  4  and secured to the upright  14  by a fastener  80 . In a like manner, a pair of uprights  17   a ,  17   b  are fixed at their lower ends by respective joints  52   b ,  52   c  near the centre of the cross member  16 , each of their upper ends engaging a mount  15   b ,  15   c  fixed to a respective chain stay  21  of the bicycle frame adjacent the rear axle. 
         [0041]    Referring to  FIGS. 2-6 , a two-part connector includes a first part  20   a  and second part  20   b . The first part  20   a  is in the form of a bracket fixed to the chain stays  21  (for instance, permanently fixed by fasteners or welding) for releasably securing the drive unit  5 . Mounting the first connector  20   a  to the chain stays  21  allows the drive unit  5  to positioned between the crank  6  and rear wheel, however it will be understood that with appropriate modification, such as extending the chain stays  21  rearwardly, the first connector  20   a  may be fixed to the frame of the bicycle behind the rear wheel. The first connector  20   a  has a transversely aligned channel  22  in which a tongue  23  on the second connector  20   b  is received. The tongue  23  has opposing shoulders  53  on either side which generally abut lips  54  on either side of the channel  22 , to support the tongue  23  vertically while allowing its transverse position to be adjusted. A fastener  24  extends (in the longitudinal direction of the watercraft  1 ) through aligned apertures in the first and second connectors  20   a ,  20   b  to connect the drive unit  5  to the bicycle. 
         [0042]    A thrust assembly  55  includes a propellor shaft  30  mounting a helical three-bladed rotor  31 . A sprocket  25  mounted on the primary shaft  26 , connected by a first pair of bevel gears  27   a ,  27   b  to the secondary shaft  28 . A second pair of bevel gears includes gear  29   a  fixed to the secondary shaft  28  and meshed with bevel gear  29   b  fixed to the propellor shaft  30 . The end of the propellor shaft  30  projecting from the housing  19  has the rotor  31  mounted to it. 
         [0043]    In  FIG. 2 , the drive unit  5  and the attached second part  20   b , are shown separated from the first part  20   a  in the transverse direction  60 . The drive unit  5  further includes an idler wheel  61  mounted on a bracket  62  connected to the tongue  23 . The chain  63  engages the sprocket  25 , crank-driven chainwheel  65  and the idler wheel  61 . The idler wheel  61  engages the loose side of the chain  63  to increase the angular engagement between the chain  63  and the sprocket  25 . 
         [0044]    The housing  19  has a tubular upper portion  19   a  and a lower portion  19   b  sealingly enclosing the lower end of the secondary shaft  28  and the propellor shaft  30 . The propellor shaft  30  is supported by bearings  32   a ,  32   b  in lower portion  19   b  for rotation about the propellor shaft axis  33 . 
         [0045]    The primary shaft  26  is supported by bearings  36   a ,  36   b  in a mount  38  for rotation about the primary shaft axis  39 . Mounted on either transverse side of the mount  38 , concentrically with primary shaft axis  39 , are bearings  40   a ,  40   b  received in respective flanges  41   a ,  41   b  fixed to the tongue  23  upon which the mount  38  and connected housing  19  are pivoted for moving the rotor  31  between the lowered position shown and a raised position (see  FIG. 8 ). 
         [0046]    Formed on the second connector  20   b , projecting inwardly between the flanges  40   a ,  40   b  is an abutment  57 . As best seen in  FIG. 4   a , a projection  38  extends radially outward of the mount  38 , a threaded aperture in the projection  60  receives a threaded fastener  56  the end of which projects to contact the abutment  57  to limit the angular tilting of the mount  38  and rotor  31 . The length adjustment achieved through rotation of the stop fastener  56  provides a trim adjustment for the drive unit. The thrust from the rotor  31  during forward movement produces a torque transmitted by the stop fastener  56  engaging the abutment  57 . 
         [0047]    The secondary shaft  28  is mounted for rotation about the secondary shaft axis  35 , the lower end held in bearing  34   a  in the housing  19  and the upper end being held in bearing  34   b  in the mount  38 . A journal  42  connects the mount  38  and housing  19   a , allowing relative rotation therebetween for directing the thrust from the rotor  31 . 
         [0048]    As shown in  FIG. 7 , the propeller shaft axis  33  can be pivoted about the secondary shaft axis  35  for steering the water craft, between the position shown for forward travel, to the rotated positions  33 ′,  33 ″.  FIG. 8  shows the rotor  31  rearwardly inclined, and raised relative to the upright position shown in dashed outline, the housing  19  having been pivoted about the primary shaft axis  39 , for instance when the water craft  1  rests upon the ground, of if the drive unit  5  strikes an obstruction. 
         [0049]    The freewheeling hub  43  of the rear wheel of the bicycle is driven in the conventional manner by chain drive from the crank  6 . While many bicycles may have multiple chainwheels coaxial with the crank  6 , in the embodiment illustrated only a single chainwheel  65  is provided on the crank, requiring the chain driving the freewheeling hub  43  to be removed when it is required to drive the drive unit  5 . 
         [0050]    A cable assembly includes a pair of sheathed cables  46 ,  47 , each comprising a sheath  67  holding a cable  68 . One end of each of the sheathed cables  46 ,  47  is fixed to the drive unit  5 , the sheaths  67  abutting respective tubular fixtures  48  through which the cables  68  extend, before passing around respective rollers  70 . The respective ends of the cables  68  are held in clamps  71  fixed to the housing portion  19   a . The rollers  70  themselves are fixed to the mount  38 , being arranged symmetrically either side of a central longitudinal plane of the drive unit  5  to direct the cable from generally radial alignment to longitudinal alignment with respect to the tubular housing portion  19   a . The opposing ends of the cables  46 ,  47  are releasably connected to the bicycle  4 , the sheaths  67  abutting respective fixtures  501  on the frames, while loops  66  in the ends of the cables  46 ,  47  are passed over nubs  51  fixed to the steering forks  49  on either side of the steering axis  167 . 
         [0051]    An alternative thrust assembly  55 ′ is illustrated in  FIGS. 9 and 10 , wherein the rotor  31 ′ includes eight substantially radially-aligned blades  51  and is mounted to the lower end of the secondary shaft  28  enclosed within a toroidal portion  50  of the housing  19 ′. A circular inlet aperture  52  is provided in the base of the toroidal portion  50  aligned with the secondary shaft axis  35  and a radially extending nozzle  53  is provided for directing a jet of water from the assembly. 
         [0052]    In its collapsed state (not shown) the water craft  1  can be stored or carried readily upon the bicycle, ready for use, together with a pump and tools required for assembly. After inflating the floats  2 , they are joined together by the front and rear cross-members  11 ,  16  to which uprights  14  and pair of uprights  17   a ,  17   b  are fixed, before clamping the bicycle in place. The drive unit  5  is fixed in place by entering the tongue  23  into the channel  22  and securing the fastener  24  before the transmission chain is connected to the sprocket  25 . To connect the steering cable assembly the sheaths  67  are attached to abut the respective fixtures  501  and the loops  66  in the ends of each of the cables  46 ,  47  are passed over the respective nubs  51 . 
         [0053]    Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.