Abstract:
A belt transmission system of a snowmobile includes a cover which has an upper cover portion and a side cover portion. The cover is pivotally mounted to the chassis of the snowmobile so that it can not only be conveniently installed or removed, but can also be pivotally opened to allow for access to the belt transmission system. The cover effectively prevents injury when the hood and side panel of fairings of the snowmobile are open. The cover further includes noise absorption material attached thereto. Thus, noise reduction is improved by better confining the noise produced by engagement of the belt with the pulleys within an inner space, and by partially absorbing the noise energy.

Description:
[0001]    This application claims the benefit of priority to U.S. Provisional Application No. 60/479,469 filed on Jun. 19, 2003, the contents of which are incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention generally relates to a snowmobile, and more particularly to a cover structure of a belt transmission system of a snowmobile.  
         BACKGROUND OF THE INVENTION  
         [0003]    A snowmobile generally includes an engine, a ski and steering assembly, a drive track assembly, a belt transmission system for transmitting power from the engine to the drive track assembly, and a chassis as a supporting base of the snowmobile. The belt transmission system includes an endless belt surrounding a pair of spaced-apart pulleys. The engine and the belt transmission system are enclosed within a fairing shell at a front portion of the snowmobile. The fairing shell usually includes a hood and at least one side panel which are openable to allow for inspection and maintenance of the engine and the belt transmission system.  
           [0004]    In a belt-breaking accident, pieces of a broken belt could be thrown around due to the angular momentum of the turning belt, particularly if the hood or side panel of the snowmobile were open during such an occurrence, as is required under certain circumstances such as engine or belt transmission system inspection, maintenance, or the like.  
           [0005]    Conventionally, a pulley cover which is an elongate and curved metal panel, is positioned above the belt and the pulleys in order to prevent pieces of a broken belt from being thrown around to potentially cause injury to persons. Conventional pulley covers also offer a certain amount of protection such that a person cannot easily place his/her hands on the turning belt or pulleys. The conventional pulley cover is conveniently mounted to the chassis of the snowmobile and can be completely removed. However, it is apparent that the protection provided by this type of conventional pulley covers can, in some circumstances, be limited. In particular, the conventional pulley cover cannot prevent catching clothing in the pulleys in all situations.  
           [0006]    Efforts have been made to develop pulley covers offering better protection. For example, some prior art vehicles provide a pulley cover with a complete housing. However, while those pulley covers provide some protection they, are inconvenient to remove or open for allowing access to the belt transmission system when required. Therefore, there is a need for an alternative belt transmission system covering structure to address these problems.  
         SUMMARY OF THE INVENTION  
         [0007]    It is one object of the present invention to provide a belt transmission system cover structure for snowmobiles which not only helps to prevent accidental access to the belt transmission system while it is turning, but also conveniently allows for access to the belt transmission system when required.  
           [0008]    In accordance with one aspect of the present invention, an apparatus for covering a belt transmission system which is operatively supported on a chassis of a snowmobile and includes an endless belt surrounding a pair of spaced apart pulleys, comprises an upper cover portion and a side cover portion. The upper cover portion is adapted for preventing access to the pulleys and belt from a top of the snowmobile. The side cover portion is attached to an outer side edge of the upper cover portion, extending downwardly therefrom, and is adapted for preventing access to the pulleys and belt from a side of the snowmobile. Means are positioned at an end of the upper cover portion for pivotally mounting the upper cover portion to the chassis, thereby permitting the upper and side cover portions to pivot away from the belt transmission system about an axis transverse to a longitudinal centerline of the snowmobile, when access to the pulleys and belt is required.  
           [0009]    The pivotal mounting means preferably comprises a pin pivotally interconnecting a front end of the upper cover portion and a mounting portion of the chassis. The upper cover portion preferably comprises a locking device located at a rear end thereof for releasably securing the apparatus in a closed position.  
           [0010]    The side cover portion preferably comprises a noise absorption structure. In one embodiment of the present invention the side cover portion includes a foam material attached to an inner side thereof.  
           [0011]    In accordance with another aspect of the present invention, there is provided a snowmobile having an engine, a ski and steering assembly, a drive track assembly, a belt transmission system for transmitting power from the engine to the drive track assembly, and a chassis as a supporting base of the snowmobile. The snowmobile further comprises a belt transmission system cover including an upper cover portion and a side cover portion attached to an outer side edge of the upper cover portion and extending downwardly therefrom. Means are provided for pivotally mounting the belt transmission system cover at a front end of the upper cover portion, to the chassis, thereby permitting the belt transmission system cover to pivot about an axis transverse to a longitudinal centerline of the snowmobile, between a first position in which the upper cover portion is disposed above the belt transmission system and the side portion is disposed at an outer side of the belt transmission system, and a second position in which the belt transmission system cover is pivoted away from the first position allowing for access to the belt transmission system when required.  
           [0012]    The snowmobile preferably comprises means for releasably securing the belt transmission system cover in the first position. The upper cover portion is preferably shaped to correspond with an upper contour of the belt transmission system. The side cover portion preferably includes a lower edge positioned at a bottom surface of the chassis when the belt transmission system cover is in the first position. It is also preferable that the snowmobile includes an external shell for enclosing the engine and belt transmission system and that the belt transmission system cover is disposed within the external shell.  
           [0013]    The belt transmission system cover according to the present invention not only effectively helps to prevent pieces of a broken belt from being thrown around in a belt-breaking event but also effectively prevents injuries caused by people placing their hands or catching their clothing on the turning belt and pulleys, and further advantageously provides a simple structure for easy installation and convenient opening when access to the belt transmission system is required.  
           [0014]    The present invention still further advantageously improves suppression of the noise produced by the belt transmission system.  
           [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]    [0017]FIG. 1 is a schematic side view of a snowmobile incorporating one embodiment of the present invention;  
         [0018]    [0018]FIG. 2 is a rear, side perspective view of a belt transmission system cover according to the embodiment of the present invention, incorporated in the snowmobile of FIG. 1;  
         [0019]    [0019]FIG. 3 is a front, side perspective view of the belt transmission system cover of FIG. 2;  
         [0020]    [0020]FIG. 4 is a partial perspective view of FIG. 1, with fairings of the snowmobile removed, showing the belt transmission system cover of FIG. 2 installed in position, with a side cover portion being partially cut away for illustrative purposes; and  
         [0021]    [0021]FIG. 5 is a partial cross-sectional view of the side cover portion, showing a layer of foam material attached thereto. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    Referring now in detail to the drawings, and primarily to FIGS. 1 and 4, a snowmobile incorporating an embodiment of the present invention is identified generally by the reference numeral  10 . Although certain facets of the present invention might be applicable in other types of vehicles, the present invention has particular utility in connection with snowmobiles.  
         [0023]    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.  
         [0024]    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 .  
         [0025]    At the front end  12  of the snowmobile  10 , there are provided fairings  54  that 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 are both openable to allow for 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.  
         [0026]    A seat  58  extends from the rear end  14  of the snowmobile  10  to the fairings  54 . A rear portion of the seat  58  may include a storage compartment or can be used to accept a passenger seat (not indicated). Two footrests  60  are positioned on opposed sides of the snowmobile  10  below the seat  58  to accommodate the rider&#39;s feet.  
         [0027]    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 . Best seen in FIG. 4, the engine output shaft drives the belt transmission system  40  and in the illustrated embodiment, the belt transmission system  40  includes a drive pulley  62 . The drive pulley  62 , in turn, drives a driven pulley  64  by way of an endless belt  66  which surrounds the pair of pulleys  62 ,  64 . The driven pulley  64  is, in turn, coupled in an appropriate manner to a drive shaft (not shown) which transmits the torque power generated by the engine  24  in a well known manner, to the endless drive track  38  for propulsion of the snowmobile  10 .  
         [0028]    Referring now to FIGS. 2-4, a transmission system cover  68  is provided to prevent pieces of a broken belt from being thrown around in a belt-breaking event, particularly when the hood and side panels of the fairings  54  of FIG. 1 are opened while the engine  24  is running. The transmission system cover  68  includes an upper cover portion  70  preferably made of aluminium. The upper cover portion  70  is formed as an elongate panel and is curved to correspond with the upper contours of the belt transmission system  40 . Thus, the upper cover portion  70  can be placed in a close relationship to the belt  66  and the pulleys  62 ,  64  when being disposed thereabove and being attached to the engine cradle portion  20  of the chassis  16 . The upper cover portion  70  when in place, can effectively prevent access to the pulleys  62 ,  64  and the belt  66  from a top of the snowmobile  10 .  
         [0029]    The transmission system cover  68  further includes a side cover portion  72  attached to an outside edge  74  of the upper cover portion  70  and extending downwardly therefrom such that access from a side of the snowmobile  10  to the pulleys  62 ,  64  and the belt  66 , is effectively prevented. The side cover portion  72  is preferably made of a plastic material. A pin  75  is received in a sleeve  76  formed at the front end of the upper cover portion  70 , with opposed ends projecting laterally therefrom. The opposed laterally projecting ends of the pin  75  are pivotally received in a pair of holes (not indicated) in a bracket  78  which is part of the chassis  16  and is disposed in the engine cradle portion  20  forward of the drive pulley  62 . The pin  75  is secured in place by well known fastening mechanisms such as clips  80 , and its longitudinal axis extends transversely to the longitudinal centerline  61  of the snowmobile  10  of FIG. 1. Thus, the transmission system cover  68  is permitted to pivot about the pin  75  between a first position (as shown in FIG. 4) in which the upper cover portion  70  is disposed above the belt transmission system  40  and the side cover portion  72  is disposed at an outer side of the belt transmission system  40 , and a second position in which the transmission system cover  68  is pivoted away from the first position thereof, as indicated by the arrow P in order to permit access to the belt transmission system  40  when required, for example, when maintenance work needs to be done on the belt  66  and/or the pulleys  62 ,  64 . Optionally, reinforcing ridges  82  can be formed at the front end of the upper cover portion  70  in order to increase the rigidity of the upper cover portion  70 .  
         [0030]    A plurality of clips  84  are fixed to the rear end of the upper cover portion  70  and are releasably engagable with complimentary components (not shown) disposed on a section of a vertical panel  86  which, as part of the chassis  16 , extends upwardly from a bottom surface  88  of the chassis  16  and is disposed immediately behind the driven pulley  64 . The clips  84  with their complimentary components provide a means for releasably securing the transmission system cover  68  in the first position. Alternatively, a securing pin (not shown) can replace clips  84  and can selectively lock the rear end of the upper cover portion  70  to the vertical panel  86  with appropriate mechanisms which are well known in the art and will not therefore be further discussed herein. Other well known types of locking devices can also be alternatively used.  
         [0031]    The side cover portion  72  has a lower edge  90  positioned to extend to the bottom surface  88  of the chassis  16 , preferably as close as possible to the bottom surface  88 , when the transmission system cover  68  is in the first position. The side cover portion  72  can be molded with laterally projecting portions or recessed portions to closely correspond to the contours of the belt transmission system  40 . Holes (not shown) through the side cover portion  72  are optional. These configurations having holes or projecting portions may be selected in some models of snowmobiles because there is not enough clearance between a flat side cover portion  72  and for example, a nut  94  which affixes the drive pulley  62  to the engine output shaft.  
         [0032]    When the snowmobile  10  is running without moving, or especially when it is moving across the ground, the engagement of the belt  66  with the pulleys  62 ,  64  produces a substantial amount of noise. In conventional snowmobiles, the noise and its reflections off the side of the bottom pan of the snowmobiles can exit through the air vents in the hood.  
         [0033]    In order to provide a noise insulation result, the side cover portion  72  is preferably profiled to cover the opening defined between the upper cover portion  70  and the bottom surface  88  of the chassis  16 , and between the vertical panel  86  of the chassis  16  and a section of the engine cradle portion  20  which is disposed forwardly of the drive pulley  62  and immediately supports the bracket  78 . Preferably, the inner side of the transmission cover  68  includes a noise absorption structure as shown in FIG. 5. For example, a layer of foam material  96  can be attached to the inner side of the side cover portion  72 . Optionally, a similar foam layer also can be applied to the inner surface of the upper cover portion  70 . Thus, the noise is kept within the space defined by the engine  24 , the upper and side cover portions  72 ,  64 , and the chassis  16 , and is partially absorbed by the foam layer  96 .  
         [0034]    The upper cover portion  70  of the illustrated embodiment is made of aluminium, but can be formed of other materials which can adequately bear the impact forces exerted thereupon by the thrown pieces of a broken belt. The plastic side cover portion  72  can be attached to the outer side edge  74  of the upper cover portion  70  by any well known and suitable fastening means. In this particular embodiment, a plurality of bolts  92  are used to bolt the side cover portion  72  together with the upper cover portion  70 . Alternatively, the transmission system cover  68  can be made as a single unit, such as an integral cover made from a blank of sheet metal in a pressing process.  
         [0035]    The entire transmission system cover  68  is disposed within the external shell of fairings  54  of FIG. 1, and is accessable and pivotally openable when a corresponding side panel of the external shell is opened. When the corresponding side panel of the external shell is opened, the transmission system cover  68  can not only be pivotally opened, but can also be completely removed from the chassis  16  by removing the clips  80  and the pin  74 .  
         [0036]    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.