Abstract:
An adjustable seat for a snowmobile has a base having an upper sitting portion for accommodating a driver and a slidable coupling for sliding the seat relative to a chassis of the snowmobile. The seat is movable between a forward position and a rearward position. Threaded fasteners or other connectors are employed to secure the adjustable seat to the chassis in an ergonomic position. The adjustable seat thus accommodates drivers of different height and/or drivers who adopt different postures when riding by comfortably seating the driver on the sweet spot of the seat regardless of the driver&#39;s height or his driving posture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of priority to U.S. Provisional application 60/620,687 filed on Oct. 22, 2004, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention generally relates to a snowmobile and, more particularly, to a seat for a snowmobile.  
       BACKGROUND OF THE INVENTION  
       [0003]     In a straddle-type vehicle such as a snowmobile, a driver conventionally sits on a seat having a substantially flat top surface with an upwardly extending back support at a rear end of the seat. The snowmobile seat typically extends over the snowmobile&#39;s chassis, extending rearward from a forwardly mounted gas tank to a rearward end of the vehicle. Ordinarily, the snowmobile seat is designed to accommodate the driver approximately midway along the vehicle so that the driver&#39;s mass, when straddling the seat and holding the handlebars, preferably aligns (in the vertical plane) with the center of mass of the vehicle, which generally enhances driver stability and vehicle performance.  
         [0004]     When seated on the straddle-type seat of a snowmobile, the driver will usually prefer to sit with his buttocks and lower back supported by the top surface of the seat and an upwardly extending back support, respectively. This position is most comfortable because it provides the most support and positional stability. This spot could be referred to as the “Sweet Spot” since some seats have a high-quality foam padding in this area to increase comfort. Due to cost constraints, usually only a portion of the snowmobile seat has a “sweet spot” made of high-quality, high-comfort foam.  
         [0005]     Although these prior-art snowmobile seats have been utilized for many years, they are sub-optimal in terms of comfort and ergonomics for at least two main reasons.  
         [0006]     First, drivers near the two extremes of the human scale are sub-optimally accommodated. In other words, a driver with short arms and legs will tend not to sit in the same spot on the seat as a driver with long arms and legs, therefore making it difficult (or expensive) to comfortably accommodate all sizes of drivers on the “sweet spot” of the seat.  
         [0007]     Second, there are two types of driving positions available on current snowmobiles. Certain models offer a driving posture in which the driver&#39;s knees are forward of his ankles and the hips are above the knees, while other models offer a different driving posture where the driver&#39;s knees are rearward of his ankles and the hips are below the knees. Although each vehicle is specific to one of the two particular driving postures, one may attempt to switch between these two driving postures thus driver is not on the “sweet spot” in both postures. Alternatively, an enlarged sweet spot that comfortably accommodates the driver is also generally considered impracticable because of the high cost of manufacturing a seat with an enlarged sweet spot.  
         [0008]     In either of these scenarios, the prior-art snowmobile seats are inadequate because the drivers of varying height and/or drivers who adopt different driving postures are not, at all times, comfortably seated on the sweet spot of the seat.  
         [0009]     Some snowmobile seats include an adjustable backrest support where the backrest or a portion thereof can be inclined at various angles. However, the sweet spot of the seat, upon which the driver sits, remains fixed. Thus, the aforementioned problems are not mitigated by the snowmobile seats having the adjustable backrest supports.  
         [0010]     Therefore, there remains a need for a seat for a snowmobile which comfortably and stably accommodates a driver of different heights and/or a driver who adopts different driving postures.  
       SUMMARY OF THE INVENTION  
       [0011]     It is an object of the present invention to provide an adjustable seat for a snowmobile that comfortably and stably accommodates different drivers who adopt different driving postures.  
         [0012]     In accordance with one aspect of the present invention, an adjustable seat for a snowmobile includes a base having an upper sitting portion for accommodating a driver. The adjustable seat also includes a slidable coupling for sliding the seat relative to a chassis of the snowmobile, the seat being movable between a forward position and a rearward position. The adjustable seat further includes at least one connector for securing the adjustable seat to the chassis.  
         [0013]     In accordance with another aspect of the present invention, a snowmobile has a chassis including a chassis; an engine disposed on the chassis at a forward end thereof, the chassis having footrests outwardly extending from either side thereof for receiving feet of a driver; at least one ski linked to the chassis by a front suspension system; a steering device disposed on the chassis forward of the seat and being operatively connected to the at least one ski for steering the snowmobile; a drive track disposed below the chassis and connected to a rear suspension system, said drive track being operatively connected to the engine for propulsion of the snowmobile; and an adjustable seat having the features described in the preceding paragraph.  
         [0014]     In accordance with yet another aspect of the present invention, a method of adjusting a seat for ergonomically accommodating a driver on a snowmobile includes the steps of sliding an adjustable seat between a forward position and a rearward position; and securing the adjustable seat to preclude movement of the seat relative to the chassis.  
         [0015]     Other features and advantages of the present invention will be better understood with reference to the preferred embodiment described hereinafter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     Having thus generally described the nature of the present invention, reference will now be made to the accompanying drawings by way of illustration showing a preferred embodiment, in which:  
         [0017]      FIG. 1  is a side view of a snowmobile incorporating an embodiment of the present invention;  
         [0018]      FIG. 2  is a side view of an adjustable seat in accordance with an embodiment of the present invention;  
         [0019]      FIG. 3  is a side view of the adjustable seat secured in a forward position;  
         [0020]      FIG. 4  is a side view of the adjustable seat secured in a rearward position with threaded fasteners;  
         [0021]      FIG. 5  is a side view of the adjustable seat secured in a rearward position with snaps;  
         [0022]      FIG. 6  is a cross-sectional view of the adjustable seat shown in  FIG. 5 ;  
         [0023]      FIG. 7  is a perspective view of the adjustable seat in the rearward position;  
         [0024]      FIG. 8  is a perspective view of the adjustable seat in the forward position;  
         [0025]      FIG. 9  is a perspective view of a fuel tank having a molded cavity and corresponding cover plate defining a slot for slidably receiving a tongue from the seat;  
         [0026]      FIG. 10  is a perspective view of an underside of the adjustable seat; and  
         [0027]      FIG. 11  is a perspective view of an underside of the adjustable seat showing threaded holes for discretely positioning the seat relative to the snowmobile chassis. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Referring now to  FIG. 1 , a snowmobile incorporating an embodiment of the present invention is designated generally by reference numeral  10 . Although certain aspects of the present invention are applicable in other types of vehicles, the present invention has particular utility in connection with snowmobiles.  
         [0029]     The snowmobile  10  includes a forward end  12  and a rearward end  14  which are defined consistently with the travel direction of the vehicle. The snowmobile  10  includes a chassis  16  which normally includes a rear tunnel  18 , an engine cradle portion  20  and a front suspension assembly portion  22 . An engine  24 , which is schematically illustrated in  FIG. 1 , is carried by the engine cradle portion  20  of the chassis  16 . A ski and steering assembly (not indicated) is provided, in which two skis  26  are positioned at the forward end  12  of the snowmobile  10  and are attached to the front suspension assembly portion  22  of the chassis  16  through a front suspension assembly  28 . The front suspension assembly  28  includes ski legs  30 , supporting arms  32  and ball joints (not shown) for operatively joining the respective ski legs  30 , supporting arms  32  and a steering column  34 . The steering column  34  at its upper end is attached to a steering device such as a handlebar  36  which is positioned forward of a rider and behind the engine  24  to rotate the ski legs  30  and thus the skis  26 , in order to steer the vehicle.  
         [0030]     An endless drive track  38  is positioned at the rear end  14  of the snowmobile  10  and is disposed under tunnel  18 , being connected operatively to the engine  24  through a belt transmission system  40  which is schematically illustrated by broken lines in  FIG. 1 . Thus, the endless drive track  38  is driven to run about a rear suspension assembly  42  for propulsion of the snowmobile  10 . The rear suspension assembly  42  includes a pair of slide rails  44  in sliding contact with the endless drive track  38 . The rear suspension assembly  42  also includes one or more shock absorbers  46  which may further include a coil spring (not shown) surrounding the individual shock absorbers  46 . Front and rear suspension arms  48  and  50  are provided to attach the slide rails  44  to the chassis  16 . One or more idler wheels  52  are also provided in the rear suspension assembly  42 .  
         [0031]     At the front end  12  of the snowmobile  10 , fairings  54  enclose the engine  24  and the belt transmission system  40 , thereby providing an external shell that not only protects the engine  24  and the belt transmission system  40 , but can also be decorated to make the snowmobile  10  more aesthetically pleasing. Typically, the fairings  54  include a hood (not indicated) and one or more side panels which can be opened to allow access to the engine  24  and the belt transmission system  40  when this is required, for example, for inspection or maintenance of the engine  24  and/or the belt transmission system  40 . In the particular snowmobile  10  shown in  FIG. 1 , the side panels can be opened along a vertical axis to swing away from the snowmobile  10 . A windshield  56  may be connected to the fairings  54  near the front end  12  of the snowmobile  10  or directly to the handlebar  36 . The windshield  56  acts as a wind screen to lessen the force of the air on the rider while the snowmobile  10  is moving.  
         [0032]     The engine  24  is a type of internal combustion engine that is supported on the chassis  16  and is located at the engine cradle portion  20 . The internal construction of the engine  24  may be of any known type, however the engine  24  drives an engine output shaft (not shown) that rotates about a horizontally disposed axis that extends generally transversely to a longitudinal centerline  61  of the snowmobile  10 . The engine output shaft drives the belt transmission system  40  for transmitting torque to the endless drive track  38  for propulsion of the snowmobile  10 .  
         [0033]     An adjustable seat  100  in accordance with embodiments of the present invention is positioned atop the chassis and extends from the rear end  14  of the snowmobile  10  to the fairings  54 . A rear portion of the adjustable seat  100  may include a storage compartment or can be used to accommodate a passenger seat (not indicated). Two footrests  60  are positioned on opposite sides of the snowmobile  10  below the adjustable seat  100  to accommodate the driver&#39;s feet.  
         [0034]      FIG. 2  is a side elevation view of the adjustable seat  100  in accordance with an embodiment of the present invention. The adjustable seat  100  is a straddle-type seat having a base  110  typically made of molded plastic as is known in the art. The plastic base  110  supports a foam padding  120  defining an upper sitting portion for accommodating a driver. The foam padding  120  includes a high-quality, high-comfort foam over a delimited portion of the seat. This high-comfort foam defines a “sweet spot” for maximum driver comfort. As is known in the art, the base and padding are usually covered by a wrapping or cover  130  made of treated leather or a synthetic waterproof leather-like material.  
         [0035]     As shown in  FIG. 2 , a front portion  105  of the adjustable seat  100  is molded to interface with a rear portion  145  of a fuel tank  140 . The adjustable seat  100  is slidably coupled to the fuel tank  140  via a slidable coupling  150 . The slidable coupling  150  enables sliding of the adjustable seat  100  relative to the chassis  16  of the snowmobile  10 . In other words, the adjustable seat  100  can be adjusted (i.e., displaced or linearly moved) between a forward position and a rearward position. It is to be understood that the adjustable seat either can adopt a plurality of fixed, discrete positions (in an incremental or stepwise manner) or it can be variably adjusted (in a “stepless” manner) to any desired position between front and rear extremities or stops.  
         [0036]     The adjustable seat  100  also includes at least one connector  160 , e.g. a bolt  162 , for securing the adjustable seat  100  to the chassis  16 . The connector(s) will be described below in greater detail.  
         [0037]     For the embodiment shown in  FIG. 2 , the slidable coupling  150  is a tongue-and-slot connection. Alternatively, the slidable coupling  150  can be any prismatic joint having a first member slidably constrained for linear motion within a second member. In the embodiment illustrated in  FIG. 2 , a tongue  152  protrudes from the front of the adjustable seat for slidingly engaging a rearwardly facing slot  154  in the fuel tank  140 .  
         [0038]      FIG. 3  shows a side elevation view of the adjustable seat  100  secured to the chassis  16  of the snowmobile  10 . In this figure, the adjustable seat  100  is shown in the forward position. The adjustable seat  100  is secured to the chassis with threaded fasteners  162 , such as bolts or screws. As shown in  FIG. 3 , the tongue  152  protrudes from the adjustable seat  100 . A plate  156  covers the U-shaped cavity that is molded into the fuel tank  140 . The plate  156  and cavity define the slot  154  into which the tongue  152  slides.  
         [0039]      FIG. 4  shows a side elevation view of the adjustable seat  100  secured to the chassis  16  in the rearward position. Again, in this embodiment, the adjustable seat  100  is secured to the chassis  16  with threaded fasteners  162 , such as bolts or screws. As noted above, the plate  156  covers the U-shaped indentation in the fuel tank  140  to define the slot  154  into which the tongue  152  slides. As shown in  FIG. 4 , when the adjustable seat  100  is backed into the rearmost position, it is preferable that the tongue remain at least partially inside the slot to prevent possible misalignment of the tongue and slot.  
         [0040]      FIG. 5  shows a side elevation view of the adjustable seat  100 , again in a rearward position, secured to the chassis  16  with a plurality of buttons or snaps  134  located on a downwardly depending skirt-like portion  136  of a leather seat cover  130  that wraps over the foam padding  120  and the plastic base  110  as shown in  FIG. 6 . The snaps  134  enable a driver to rapidly detach the cover  130  and readjust the position of the seat  100  relative to the chassis  16 . The snaps  134  (or buttons) located on the downwardly depending skirt-like portion  136  can be snapped onto the tunnel of the chassis  16  for securing the seat  100  relative to the chassis  16 . The snaps  134  can be easily and quickly snapped off for readjusting the position of the seat  100  relative to the chassis  16 . Other known types of quick connectors, fasteners or locking devices can be used as connectors in lieu of the bolts or snap-on buttons.  
         [0041]      FIG. 7  and  FIG. 8  show the adjustable seat  100  in the rearward and forward positions, respectively. It is to be understood that the adjustable seat  100  can be secured relative to the chassis not only at the rearward and forward extremities but also (optionally) at a plurality of intermediate positions. Indeed, in the embodiment shown in  FIG. 7  and  FIG. 8 , three discrete positions are available. Markings such as XL, L and M (for extra large, large and medium) can be inscribed on the side of the chassis to indicate the position of the seat (corresponding, for example, to the size of the driver). Alternatively, markings can be inscribed to indicate seat positions corresponding to various driving postures, e.g. “cruising posture”, “racing posture”, etc.  
         [0042]      FIG. 9  shows a fuel tank  140  with a slot  154  for receiving a tongue (not shown in this figure) in accordance with one embodiment of the present invention. The fuel tank  140  is molded to have an indentation, depression or cavity over which the covering plate  156  is affixed. In one embodiment, the cavity is U-shaped so as to receive a tongue with rounded edges. As shown in  FIG. 9 , four holes are bored and tapped (threaded) into the fuel tank  140  to receive the threaded fasteners  158  for affixing the plate  156  to the fuel tank  140 . The plate  156  is preferably made of metal or plastic and has a plurality of holes  157  through which threaded fasteners  158  are inserted in order to fasten the plate  156  over the U-shaped cavity to form the slot  154 .  
         [0043]      FIG. 10  illustrates an underside  112  of the base  110  of the adjustable seat  100  in accordance with one embodiment of the present invention. As shown in FIG.  10 , the tongue  152  is fastened to the underside  112  of the base  110  via a tongue-holding bracket  155 . The bracket is preferably fastened to the base using a plurality of threaded fasteners, although persons of ordinary skill in the art will appreciate that other means of fastening may be suitably employed. The tongue-holding bracket  155  is shaped to fit flush with the underside  112  of the base  110  thereby enabling stable connection of the tongue-holding bracket  155  to the base  110 . The tongue-holding bracket  155  holds the tongue  152  away from the underside  112  in a spaced-apart, substantially parallel posture that enables the tongue  152  to fit (and thereafter slide) into the slot in the fuel tank. The tongue  152  is preferably made of metal or high-strength plastic. The tongue  152  and slot  154  are manufactured with mutual tolerances (e.g. a sliding fit tolerance) so that the tongue  152  slides freely within the slot  154  but is nonetheless constrained to move only in a single degree of freedom, i.e. the tongue is constrained to translate or slide relative to the slot, but cannot move vertically or laterally nor can it rotate about an axis.  
         [0044]      FIG. 11  is a perspective view of the underside  112  of the base  110  of the adjustable seat  100  in accordance with an embodiment of the present invention. In this embodiment, there are three tapped (threaded) holes  170  provided to receive corresponding threaded fasteners (not shown in this figure) for securing the adjustable seat  100  relative to the chassis  16 . As persons of ordinary skill in the art will readily appreciate, the number of holes can be varied to provide more or fewer positions. Other known types of fasteners can also be substituted to provide a detachable connection for selectively adjusting the position of the seat.  
         [0045]     In the foregoing embodiments, the adjustable seat  100  can be secured relative to the chassis at a discrete number of positions. In other words, the adjustable seat  100  can be secured at one of a plurality of discrete positions to provide incremental, stepwise adjustment of the seat.  
         [0046]     In yet a further embodiment, the adjustable seat  100  can have infinitely variable adjustment by providing a connector (or a plurality of connectors) that is variably adjustable. For example, a gripping or clamping assembly would enable the base of the seat to frictionally engage the chassis at any position from the forward position to the rearward position, thereby providing infinitely variable adjustment of the seat. For example, a clamping lock would enable a user to finely adjust the position of the seat relative to the chassis and then to lock the seat to the chassis. Any number of known clamping, gripping or locking devices can be used to frictionally immobilize the seat relative to the chassis.  
         [0047]     In yet a further embodiment shown in, the slidable coupling of the adjustable seat  100  has a pair of C-shaped extensions  172  protruding forwardly from the base of the seat. The C-shaped extensions  172  are slidably received within a respective pair of larger C-shaped channels  174  formed in the tunnel  18  of the chassis  16 . The larger C-shaped channels  174  have inner dimensions corresponding to outer dimensions of the C-shaped extensions  172 , thereby constraining the C-shaped extensions  172  to move only linearly relative to the C-shaped channels  174 . As will be appreciated by those of ordinary skill in the art, the slidable coupling  150  can be any sliding joint (also known as a prismatic joint) that enables linear displacement (i.e., translation) of the adjustable seat relative to the chassis.  
         [0048]     The adjustable seat  100  is a straddle-type seat commonly found on snowmobiles. The present invention therefore can be applied to either types of straddle-type vehicles, such as personal watercraft or all-terrain vehicles where seat adjustability is desirable so as to optimally accommodate a driver on the seat.  
         [0049]     Modifications and improvements to the above-described embodiment of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.