Abstract:
A vehicle steering arrangement for an amphibious vehicle having retractable steered wheels with which the steering input to such wheels is automatically substantially curtailed upon retraction of the wheels. Retraction of the wheels causes a steering link to swing toward its steering axis to thereby reduce its effective radius while steering input to a marine propulsion remains unchanged. The reduced steering input to the wheels reduces space needed to accommodate the wheels in their retracted position.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Great Britain Application Serial No. 0423483.7, filed Oct. 22, 2004.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to vehicle steering arrangements and in particular to such arrangements for vehicles with retractable wheels.  
         [0003]     Front wheels which are arranged to be steered and retracted for an amphibious vehicle are shown in our copending International Patent Application No PCT/GB04/001422. In that arrangement the wheels are retracted through nearly 90° so as to enable good clearance of the water; but also because there is plenty of room for accommodating the wheels. At the end of each steering arm articulatedly connected between the arm and an upright member on which the road wheel is mounted is a link, which is also articulated to the upright member. When the road wheel is protracted, the link is mostly horizontal and acts as an extension to the steering arm so as to steer the road wheel. When the road wheel is retracted, the link is mostly upright so that any movement of the steering arm such as occurs when steering the vehicle in water by directing a pump jet at the rear is not, or is largely not transmitted to the pivotally mounted upright member.  
         [0004]     Therefore the retracted road wheels are not or are largely not caused to pivot. Any movement of the road wheels can be accommodated within pockets provided for accommodating most of the road wheels. In a case where it is not possible to rotate a steered suspension for a pair of road wheels to an angle as much as PCT/GB04/001422 indicates, any linkage as shown in that patent application will cause the road wheels to pivot when the vehicle is steered in water. To allow for this movement of the road wheels, the wheel pockets would have to be excessively large. This would result in loss of body space and could cause problems when the vehicle tramped on water, as the clearance around the wheels could allow water to be scooped up, causing excess spray and impeding forward progress.  
         [0005]     Where it is necessary to retract the road wheels further so that the link at each end of the steering which connects to the upright member is, at full retraction, beyond vertical, that is, the link is angled inwards at, for instance, 20° to the vertical, then the same problem occurs as when the link is angled outwards, as described in the paragraph above.  
       SUMMARY OF THE INVENTION  
       [0006]     According to a first aspect of the invention, there is provided a vehicle steering arrangement comprising at least a pair of steerable wheels, each mounted to a suspension arrangement arranged to swing upwards from a protracted road position to a retracted marine position, means associated with the suspension arrangement connected to a swingable connection on a steering column, the connection being connected to a track rod, the track rod having at each end a link articulatedly connected to an upright member of the suspension arrangement, the swingable connection on the steering column being so arranged that movement of the suspension from protraction to retraction causes the connection to swing from an active position whereby rotation of the steering column causes the track rod to move transversely and steer the road wheels, to an inactive position whereby rotation of the steering column is unable to fully move the track rod from a fully left to a fully right road steering position.  
         [0007]     Throughout this specification (description and claims) it should be understood that the term “suspension upright” does not require a component to extend exactly vertically, but instead refers to a component to which the upper and lower suspension arms are connected at points spaced apart vertically.  
         [0008]     According to a second aspect, the invention provides a suspension and steering arrangement for an amphibious vehicle comprising: 
        at least a pair of steerable wheels each mounted for rotation on a hub assembly which in turn is mounted on a suspension arm;     a retraction mechanism for raising and lowering the suspension arms between a lowered location for land mode operation of the vehicle and a raised location for marine mode operation of the vehicle; and     a steering mechanism for steering the steerable wheels including:     a steering column;     a swing arm connected to the steering column by column connection means, the swing arm rotating with the steering column about an axis of the steering column and a distal end of the swing arm, furthest from column connection means, being connected by articulated connection means to a steering connector through which steering movement is imparted onwards through the steering mechanism; and     rotation means for rotating the swing arm about the column connection means, wherein:     the column connection allows the rotation means to rotate the swing arm between an extended position in which the distal end of the swing arm is furthest from the axis of rotation of the steering column and a retracted position in which the distal end of the swing arm is nearest to the axis of the steering column; and     the rotation means is interconnected with the retraction mechanism so that on raising of the suspension arms the rotation means rotates the swing arm from the extended position to the retracted position thereof and on lowering of the suspension arms the rotation means rotates the swing arm from the retracted position to the extended position.        
 
         [0017]     In a third aspect the present invention provides a suspension and steering arrangement for an amphibious vehicle comprising: 
        at least a pair of steerable wheels each mounted for rotation on a hub assembly which in turn is mounted on a suspension arms;     a retraction mechanism for raising and lowering the suspension arm;     a retraction mechanism for raising and lowering the suspension arms between a lowered location for land mode operation of the vehicle and a raised location for marine mode operation of the vehicle; and     a steering mechanism for steering the steerable wheels including:     a steering column;     a swing arm connected to the steering column by column connection means, the swing arm rotating with the steering column about an axis of the steering column and a distal end of the swing arm, furthest from the column connection means, being connected by articulated connection means to a steering connector through which steering movement is imparted onwards through the steering mechanism; and     rotation means for rotating the swing arm about the column connection means; wherein:     the column connection means allows the rotation means to rotate the swing arm between an extended position in which the swing arm extends radially from the axis of rotation of the steering column and a retracted position in which the swing arm extends parallel to the axis of the steering column; and     the rotation means is interconnected with the retraction mechanism so that on raising of the suspension arms the rotation means rotates the swing arm from the extended position to the retracted position thereof and on lowering of the suspension arms the rotation means rotates the swing arm from the retracted position to the extended position.        
 
         [0027]     Deactivation of the road wheel steering reduces the pocket size for the wheels when retracted and the same steering column can be used to steer a water propulsion unit.  
         [0028]     The suspension preferably comprises an upper wishbone connected to the upright member and a lower suspension member connected to the upright member and resilient means connected to the suspension to enable the wheels to have controlled vertical movement when in road mode. The arrangement of the suspension is such that if the steering is not centred, that is, if the wheels are “on lock”, then the track rod with its extension link is extended to one side of the vehicle. As the wheels are retracted and the suspension starts to swing upwards, the centre of rotation of the suspension must also apply to the centre of rotation of the extension link about the end of the track rod. If the wheels are “on lock”, then the upward rotational force on the suspension during retraction will cause the steering arm to centre so that the centre of rotation of the extension link is consistent with the effective centre of rotation of the suspension.  
         [0029]     The provision of the track rod extension and its relationship to the retractable suspension therefore ensures that the road wheels neatly tuck away into a minimum space which can be readily shielded by a fairing so that they are recessed or else if only partly recessed, then the wheels, because they are centred, present a minimum frontage to the water on which the vehicle is travelling, into which it is tramping.  
         [0030]     Preferably a retraction means is connected to a retraction arm, the retraction arm being connected to a suspension arrangement for moving at least one wheel between the protracted and retracted positions.  
         [0031]     Preferably the swingable connection on the steering column is swung by means of a cable which extends from a retraction arm to an arrangement on the steering column.  
         [0032]     The arrangement on the steering column is preferably an at least partly rotatable element to which the swingable connection is connected. The swingable connection may swing about an axis intersecting the axis of the steering column.  
         [0033]     A lock may be provided to ensure that road steering is always active whenever the road wheels are protracted.  
         [0034]     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 present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]     An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which;  
         [0036]      FIG. 1  is a view from the rear and partly to one side of a steering arrangement according to the invention with road wheels as shown in broken lines protracted;  
         [0037]      FIG. 2  is a plan view from above of  FIG. 1  omitting the steering handles connected to the steering column with the wheels protracted and the wheels (not shown) steering slightly to the right;  
         [0038]      FIG. 3  is a front elevation of  FIG. 1  with the wheels protracted;  
         [0039]      FIG. 4  is a front elevation of  FIG. 1  with the wheels retracted (the right wheel being fully retracted and the left only partly retracted).  
         [0040]      FIG. 5  is a side elevation of  FIG. 1  with the wheels protracted; and  
         [0041]      FIGS. 6 and 7  are diagrammatic views of a mechanism for the arrangement of  FIG. 1  for making the steering inactive relative to the road wheels. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]     In FIGS.  1  to  5  there is shown a frame  1  which is arranged to be mounted in the front of an amphibious vehicle. The frame has swingably mounted to it left and right suspensions  3  and  5  as seen from the rear of the vehicle.  
         [0043]     Each suspension  3  and  5  comprises an upright member  7  (see  FIG. 3 ) connected to a lower suspension arm  9  and an upper wishbone  11 . Wheels  13  and  15  (shown in broken lines in  FIG. 1 ) are each mounted to a hub  14 , which is rotatably carried on upright member  7 . The hub  14  and upright member  7  together form a hub assembly.  
         [0044]     Extending forwardly of out from the upright member  7  is a steering arm  17  (see especially  FIG. 2 ) to which is connected a track rod extension  19  at its outer end  21 . The inner end of extension  19  is connected to track rod  23 . The track rod  23  is moved transversely by means of link  25  which is connected to a swingable connection (or swing arm)  27  (see  FIG. 2 ) on steering column  29 . Connection  27  is mounted to column  29  so as to be able to swing about axis X and is connected by means of arbor  31  (see  FIG. 6 ) to wheel  33 . Wheel  33  is rotatably mounted to the bottom part of column  29  for actuation by means of cable  35  connected to a swing arm  37  which is pivotally mounted to frame  1  at  39 .  
         [0045]     An actuator  41  having piston rod  43  acts on one arm of swing arm  37  to pivot the arm, the outer ends of which are connected to piston rods  44  of suspension dampers  45 , which are surrounded by coil springs  46 . The base of each suspension damper  45  is connected at  47  to retraction arm  49  pivotally mounted at  51  to frame  1  so that on retraction each upper/lower suspension arm pair of the suspension swings about an axis running longitudinally fore and aft along the vehicle.  
         [0046]      FIG. 4  shows the right hand suspension (on the left in  FIG. 4 ) with the extension  19  almost vertical. If the left hand suspension were only retracted a degree or so further then any rotation of column  29  would have no effect on rotation of upright member  7 . Once, however, retraction takes extension  19  past the vertical as shown on the right of  FIG. 4 , any movement of track rod  23  caused by handle bars  60 , column  29  and link  25  would again cause the wheels to be steered. As that is not wanted in the retracted position but marine steering is required, the mechanism shown in  FIGS. 6 and 7  is provided.  
         [0047]     Diagrammatically  FIG. 7  shows a steerable propulsion unit  70 , suitably a water jet unit, which is linked via links  72 ,  73 , and  74  to the column  29  which pivots about axis Y. So as to disable or deactivate the road steering, axes X and Y intersect at the pivot point  75  of connection  27  so that any rotation of the column about axis Y results in minimal action on link  25 .  
         [0048]      FIG. 7  shows the marine mode, with marine steering active, and road steering deactivated. Swingable connection  27  stands substantially vertically, and substantially along axis X so that rotation of handlebars  60  and steering column  29  has negligible effect on link  25  and therefore track rod  23 . Therefore the road wheels move only fractionally when the vehicle is steered on water. As the road wheels are retracted from the protracted position shown in  FIG. 3  to the retracted position shown in  FIG. 4 , swing arm  37  is rotated by cylinder  41  ( FIG. 2 ), causing said retraction of suspension and therefore wheels. As swing arm  37  rotates, the proximal end of cable  35  is pulled. The distal end of cable  35  therefore rotates wheel  33 , which in turn rotates arbor  31 , and thus connection  27  in direction R in  FIG. 6 , until connection  27  is substantially vertical.  
         [0049]     To effect wheel protraction, cylinder  41  extends, and swing arm  37  rotates in the opposite sense to that for protraction. Cable  35  is then pushed, causing wheel  33  to rotate in direction P in  FIG. 7 , until connection  27  is substantially horizontal, as shown in  FIG. 6 . Alternatively the wheel  33  could be spring-biased and rotated against the spring bias by the cable in tension and then rotates under the bias of the spring in the opposite directions. As the distal end of connection  27  now lies at a radius from axis X, it is once more able to steer the vehicle through link  25  and track rod  23 . Marine steering will still be engaged in this land mode, however as no water is passing through the jet drive on land, it will have no effect other than to swing the steering bucket from side to side.  
         [0050]     To prevent accidental disengagement of road steering on land, it is a simple matter to provide a lock to hold connection  27  in a substantially horizontal position. This could be achieved by providing a solenoid driven pin which locks connection  27  down once mode change form marine to land is complete. The use of such an electrical drive is convenient in that the pin firing signal can be made part of the vehicle mode change from marine mode to land mode. Alternatively, hydraulic or pneumatic power may be used, according to preference.  
         [0051]     A locking mechanism is shown in part in  FIG. 5 , comprising a sliding sleeve  100  aligned with column  29  with a slot for engaging and holding in position the swing arm  27 . The wheel  33  is connected to the sleeve  100  so that the sleeve  100  is slid axially in one direction (against the force of a biasing spring  101 ) to release the swing arm  27  to move freely as the wheel is rotated in one direction; the rotation of the wheel  33  in the other direction allows the sleeve to slide in the other direction under the action of the spring  101  to engage the connection  27  in its slot and hold it fast.  
         [0052]     It should be noted that further refinements may be made to the steering arrangement described above without departing from the essential inventive concept. For example, an individual retraction arrangement could be provided for each road wheel, as described in the applicant&#39;s co-pending application published as W002/44006. The suspension may not use coil springs, but may use torsion bars; or a combined hydraulic spring, damper, and retraction unit, as described in the applicant&#39;s co-pending application published as WO01/74612. Alternatively, wheel retraction may be powered pneumatically or electrically. The steering mechanism may have power assistance. The marine drive may be an open propeller, or a ducted propeller. Accordingly, it is not intended that the invention be limited except by the appended claims.