Snowmobile and features thereof allowing for different tunnel widths

A family of snowmobiles having different tunnel widths is disclosed. A snowmobile having spacers between the tunnel and the sides of the engine compartment and a method of manufacturing such a snowmobile are also disclosed. A snowmobile having a countershaft which is disposed rearwardly of the engine, vertically higher than the air intake opening, and forwardly of the air intake controller is also disclosed.

FIELD OF THE INVENTION

The present invention relates to a snowmobile and features thereof which allow for different tunnel widths.

BACKGROUND OF THE INVENTION

In snowmobiles, transverse mass centralization is important in order to have good handling characteristics. If too much mass is placed to one side of the snowmobile, the snowmobile will tend to sink into the snow on that side making it difficult to steer. This is particularly true when the snowmobile is used in soft powdered snow.

Conventionally, snowmobiles have a pair of skis and an endless drive track for propelling the snowmobile, both of which are mounted to a frame of the snowmobile. The frame includes an engine compartment which conventionally has left and right sides, a bottom, a rear (bulkhead), and a front portion. The engine compartment supports power pack components such as an engine, a tuned pipe, a muffler, a reduction gearing, and a continuously variable transmission (CVT). The frame also includes a tunnel rearward of the engine compartment below which the endless drive track is disposed. It is common to have snowmobiles having a tunnel width of 34.3 cm (13.5 inches), 38.1 cm (15 inches), 50.8 cm (20 inches), or 61 cm (24 inches), depending on the intended use of the snowmobile. The CVT has a drive pulley mounted to an output shaft of the engine, a driven pulley, and a belt looped around the two pulleys. The driven pulley is mounted to a countershaft and has a portion thereof which extends next to a side of the tunnel. The countershaft is operatively connected to the endless drive track so as to drive the endless drive track.

Since the engine is the component of the snowmobile which has the largest mass, it is important that the engine be centered as much as possible with respect to the longitudinal centerline of the snowmobile. However, this may not always be possible.

Since a portion of the driven pulley extends next to a side of the tunnel, as mentioned above, for two snowmobiles having different tunnel widths and identical power packs, the snowmobile having the larger tunnel width will need to have the engine more offset to one side of its longitudinal centerline than the other snowmobile, otherwise the driven pulley would interfere with the tunnel. This results in an unbalance in the transverse mass disposition. This unbalance can be counteracted by locating other components of the power pack on the other side of the longitudinal axis of the snowmobile. While this enables designers to design snowmobiles with different tunnel widths, it can be time consuming and costly since many parts of the power pack have to be relocated and/or redesigned each and every time a wider tunnel width is desired. Therefore each tunnel width requires its own power pack configuration. This can sometimes result in having to adopt different assembly procedures to accommodate the different power pack configurations which may increase production time and therefore the overall manufacturing cost of the snowmobiles.

Therefore, there is a need for a family of snowmobiles where the members of the family can be designed with different tunnels, having different tunnel widths, while reducing the changes that have to be made to the power pack configuration as compared with conventional snowmobiles.

SUMMARY OF THE INVENTION

It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art.

It is also an object of the present invention to provide a family of snowmobiles where the members of the family have engine compartments with the same engine compartment configuration, but have tunnels with different tunnel widths.

In one aspect, the invention provides a family of snowmobiles having a first snowmobile and a second snowmobile. The first snowmobile has a first frame. The first frame includes a first engine compartment having an engine compartment configuration and a first tunnel rearward of the first engine compartment and having a first tunnel width. A first engine is disposed in the first engine compartment. A first countershaft traverses the first engine compartment. A first continuously variable transmission (CVT) operatively connects the first engine with the first countershaft. The first CVT is disposed on a first side of the first engine. A first reduction gearing is operatively connected to the first countershaft on a second side of the first engine opposite the first side. A first endless drive track is disposed below the first tunnel for propelling the first snowmobile. The first endless drive track is operatively connected to the first reduction gearing. A first pair of skis is connected to the first frame. The second snowmobile has a second frame. The second frame includes a second engine compartment having the engine compartment configuration, and a second tunnel rearward of the second engine compartment and having a second tunnel width being greater than the first tunnel width. A second engine is disposed in the second engine compartment. A second countershaft traverses the second engine compartment. A second CVT operatively connects the second engine and the second countershaft. The second CVT is disposed on a first side of the second engine. A second reduction gearing is operatively connected to the second countershaft on a second side of the second engine opposite the first side. A second endless drive track is disposed below the second tunnel for propelling the second snowmobile. The second endless drive track is operatively connected to the second reduction gearing. A second pair of skis is connected to the second frame.

In a further aspect, the first engine has engine physical characteristics and the second engine has the engine physical characteristics. The first countershaft has countershaft physical characteristics and the second countershaft has the countershaft physical characteristics. The first CVT has CVT physical characteristics and the second CVT has the CVT physical characteristics. The first reduction gearing has reduction gearing physical characteristics and the second reduction gearing has the reduction gearing physical characteristics.

In an additional aspect, the first engine, the first countershaft, the first CVT, and the first reduction gearing are disposed in a power pack configuration relative to the first engine compartment. The second engine, the second countershaft, the second CVT, and the second reduction gearing are disposed in the power pack configuration relative to the second engine compartment.

In a further aspect, the first endless drive track has a first track width and the second endless drive track has a second track width which is greater than the first track width.

In an additional aspect, the second snowmobile further includes a first spacer disposed between the second tunnel and a first side of the second engine compartment, and a second spacer disposed between the second tunnel and a second side of the second engine compartment.

In a further aspect, the second tunnel includes a central tunnel portion having a first side and a second side, a first tunnel side portion fastened to the first side of the central tunnel portion, and a second tunnel side portion fastened to the second side of the central tunnel portion.

In an additional aspect, the central tunnel portion comprises a heat exchanger.

In a further aspect, the first spacer is disposed between the first tunnel side portion and the first side of the second engine compartment. The second spacer is disposed between the second tunnel side portion and the second side of the second engine compartment.

In an additional aspect, the first CVT has a driven pulley disposed vertically higher than the first tunnel, and the second CVT has a driven pulley disposed vertically higher than the second tunnel.

In another aspect, the invention provides a snowmobile having a frame which includes an engine compartment, a tunnel rearward of the engine compartment, a first spacer disposed between the tunnel and a first side of the engine compartment, and a second spacer disposed between the tunnel and a second side of the engine compartment.

In another aspect, the invention provides a snowmobile having a frame. The frame includes an engine compartment having a first side and a second side, a tunnel rearward of the engine compartment, a first spacer disposed between the tunnel and the first side of the engine compartment, and a second spacer disposed between the tunnel and the second side of the engine compartment. An engine is disposed in the engine compartment. A countershaft traverses the engine compartment. A continuously variable transmission (CVT) operatively connects the engine with the countershaft. The CVT being disposed on a first side of the engine. An endless drive track is disposed below the tunnel for propelling the snowmobile. The endless drive track is operatively connected to the countershaft. A front suspension is connected to the frame. A pair of skis is connected to the front suspension.

In an additional aspect, the snowmobile also has a reduction gearing operatively connected to the countershaft on a second side of the engine opposite the first side. The endless drive track is operatively connected to the reduction gearing.

In a further aspect, the tunnel includes a central tunnel portion having a first side and a second side, a first tunnel side portion fastened to the first side of the central tunnel portion, and a second tunnel side portion fastened to the second side of the central tunnel portion.

In an additional aspect, the central tunnel portion comprises a heat exchanger.

In a further aspect, the first spacer is disposed between the first tunnel side portion and the first side of the engine compartment, and the second spacer is disposed between the second tunnel side portion and the second side of the engine compartment.

In an additional aspect, the CVT has a driven pulley disposed vertically higher than the tunnel.

In a further aspect, the front suspension includes two pairs of A-arms.

In another aspect, the invention provides a method of manufacturing a snowmobile frame having spacers between the tunnel and the sides of the engine compartment.

In another aspect, the invention provides a method of manufacturing a snowmobile frame. The method comprises providing an engine compartment having a first side and a second side, disposing a tunnel rearwardly of the engine compartment, inserting a first spacer between the tunnel and the first side of the engine compartment, and inserting a second spacer between the tunnel and the second side of the engine compartment.

In an additional aspect, the tunnel comprises a central tunnel portion having a first side and a second side, a first tunnel side portion, and a second tunnel side portion. The method further comprises fastening the first tunnel side portion to the first side of the central tunnel portion, and fastening the second tunnel side portion to the second side of the central tunnel portion.

In a further aspect, the first spacer is inserted between the first tunnel side portion and the first side of the engine compartment, and the second spacer is inserted between the second tunnel side portion and the second side of the engine compartment.

In an additional aspect, the tunnel has a tunnel width and the engine compartment has an engine compartment width. The tunnel width is greater than the engine compartment width.

In another aspect, the invention provides a snowmobile having a countershaft traversing an engine compartment of the snowmobile, where the countershaft is disposed rearwardly of the engine, vertically higher than an air intake opening of the engine, and forwardly of an air intake controller.

In another aspect, the invention provides a snowmobile having a frame. The frame includes an engine compartment and a tunnel rearward of the engine compartment. An engine is disposed in the engine compartment. The engine has at least one air intake opening on a rear side thereof. An air intake controller is disposed rearwardly of the engine and fluidly communicates with the air intake opening. A countershaft traverses the engine compartment. The countershaft is disposed rearwardly of the engine, vertically higher than the air intake opening, and forwardly of the air intake controller. A continuously variable transmission (CVT) operatively connects the engine with the countershaft. An endless drive track is disposed below the tunnel for propelling the snowmobile. The first endless drive track is operatively connected to the countershaft. A front suspension is connected to the frame. A pair of skis is connected to the front suspension.

In an additional aspect, the air intake controller is one of a carburetor and a throttle body.

In a further aspect, the CVT is disposed on a first side of the engine. The snowmobile also has a reduction gearing operatively connected to the countershaft on a second side of the engine opposite the first side.

In an additional aspect, the engine has an output shaft. The snowmobile also has a drive axle disposed in the tunnel. The drive axle is operatively connected to the countershaft for driving the endless drive track.

In a further aspect, the countershaft is disposed rearwardly of the output shaft and forwardly of the drive axle.

In an additional aspect, the countershaft defines a countershaft axis. The countershaft axis is generally vertically aligned with a top portion of the engine.

In another aspect, the invention provides a family of snowmobiles where frames of the members of the family have engine compartments with the same engine compartment configuration, but have tunnels with different tunnel widths, and where the distance from a side of the engine to a longitudinal centerline of the frame for each member of the family is the same.

In another aspect, the invention provides a family of snowmobiles having a first snowmobile and a second snowmobile. The first snowmobile has a first frame. The first frame includes a first longitudinal centerline, a first engine compartment having a first engine compartment configuration, and a first tunnel rearward of the first engine compartment. The first tunnel has a first tunnel width. A first engine is disposed in the first engine compartment. The first engine has engine characteristics, a first side and a second side opposite the first side. The first side is disposed a first distance from the first longitudinal centerline. A first countershaft traverses the first engine compartment. A first continuously variable transmission (CVT) operatively connects the first engine with the first countershaft. The first CVT is disposed on the first side of the first engine. A first reduction gearing is operatively connected to the first countershaft on the second side of the first engine. A first endless drive track is disposed below the first tunnel for propelling the first snowmobile. The first endless drive track is operatively connected to the first reduction gearing. A first pair of skis is connected to the first frame. The second snowmobile has a second frame. The second frame includes a second longitudinal centerline, a second engine compartment having a second engine compartment configuration, and a second tunnel rearward of the second engine compartment. The second tunnel has a second tunnel width being greater than the first tunnel width. A second engine is disposed in the second engine compartment. The second engine has the engine characteristics, a first side and a second side opposite the first side. The first side is disposed a second distance from the second longitudinal centerline. The second distance is the same as the first distance. A second countershaft traverses the second engine compartment. A second CVT operatively connects the second engine and the second countershaft. The second CVT is disposed on the first side of the second engine. A second reduction gearing is operatively connected to the second countershaft on the second side of the second engine. A second endless drive track is disposed below the second tunnel for propelling the second snowmobile. The second endless drive track is operatively connected to the second reduction gearing. A second pair of skis is connected to the second frame.

In a further aspect, the first endless drive track has a first track width, and the second endless drive track has a second track width being greater than the first track width.

In an additional aspect, the second snowmobile also has a first spacer disposed between the second tunnel and a first side of the second engine compartment, and a second spacer disposed between the second tunnel and a second side of the second engine compartment.

In a further aspect, the first CVT has a driven pulley disposed vertically higher than the first tunnel, and the second CVT has a driven pulley disposed vertically higher than the second tunnel.

In another aspect, the invention provides a method of manufacturing a snowmobile frame and power pack by providing an engine compartment, selecting a tunnel from a group of tunnels each having a different width, disposing the selected tunnel rearwardly of the engine compartment, and disposing the power pack in the engine compartment.

In another aspect, the invention provides a method of manufacturing a snowmobile frame and power pack. The power pack includes an engine, a CVT on a first side of the engine, the CVT having a driven pulley, a reduction gearing on a second side of the engine opposite the first side, and a countershaft operatively connecting the driven pulley with the reduction gearing. The method comprises providing an engine compartment having a engine compartment configuration adapted to receive the power pack, selecting one of a first tunnel and a second tunnel, the first tunnel having a first tunnel width, the second tunnel having a second tunnel width, the second tunnel width being different from the first tunnel width, disposing the selected one of the first tunnel and the second tunnel rearwardly of the engine compartment, and disposing the power pack in the engine compartment, wherein the driven pulley is disposed vertically above the selected one of the first tunnel and the second tunnel.

In an additional aspect, disposing the power pack in the engine compartment includes locating the driven pulley at a first distance from a longitudinal centerline of the frame when the first tunnel is selected, and locating the driven pulley at a second distance from the longitudinal centerline of the frame when the second tunnel is selected. The first distance is the same as the second distance.

In a further aspect, the method further comprises inserting a first spacer between the selected one of the first tunnel and the second tunnel and a first side of the engine compartment, and inserting a second spacer between the selected one of the first tunnel and the second tunnel and a second side of the engine compartment.

For purposes of this application, the term “configuration” means the relative arrangement of components. For example, the power pack configuration refers to the arrangement of the engine, CVT, reduction gearing, and other power pack components relative to each other. The terms “physical characteristics” mean the features of a component. For example, the engine physical characteristics of an engine could include, but are not limited to, the number of cylinders, the type of cycle it operates on (two-cycle or four cycle), the engine's dimensions, and the engine's horsepower. The terms “power pack” mean the combination of an engine and components for transmitting power from the engine. These components could include, but are not limited to, one or more of a CVT, a reduction gearing, and a shaft. The term “tunnel” means the rear portion of the frame of a snowmobile that has a generally inverted U-shaped transverse cross-section. The tunnel houses at least a portion of the endless drive track of the snowmobile therein and the seat of the snowmobile is at least partially disposed on the tunnel.

Embodiments of the present invention each have at least one of the above-mentioned aspects, but do not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attaining the above-mentioned objects may not satisfy these objects and/or may satisfy other objects not specifically recited herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aspects of the present invention relate to a family of snowmobiles. However, since each member of the family of snowmobiles has common features only one snowmobile10will be described herein in detail for simplicity. Even though only one snowmobile10is described, it should be understood that features of members of the snowmobile family that are not directly related to the invention, such as the skis or seat for example, may be different from one member to the other without deviating from the invention.

As will become apparent from the following description, the members of the family each have a different frame16A (FIGS. 2 to 9),16B (FIGS. 10 to 12), or16C (FIGS. 13 to 19) but other features, such as a power pack102, can remain generally the same. As will also become apparent from the following description, the different frames16A,16B, and16C each have a corresponding tunnel18A,18B, and18C, each of which has a different tunnel width to accommodate different widths of endless track65, but each have an engine compartment20which has generally the same engine compartment configuration as the others. It should be understood that throughout this application the term “same” does not require the components referred to as such to be exactly identical and that minor variations between these elements are contemplated. By way of non-limiting example, the frames16A,16B, and16C could have different bracket physical characteristics to accommodate different optional components of the particular snowmobile10. For simplicity, components which are different in each embodiment will be referred to by their reference numeral and corresponding letter when referring to a specific one of the components (e.g. tunnel18A) but will only be referred to by their reference numeral when the description could apply to any one of the embodiments (i.e. tunnel18will be used when referring to any one of tunnels18A,18B, and18C).

As seen inFIG. 1, the snowmobile10, the description of which can correspond to any member of the family of snowmobiles, includes a forward end12and a rearward end14which are defined consistently with a travel direction of the snowmobile10. The snowmobile10includes a frame16(16A,16B, or16C) which includes a tunnel18(18A,18B, or18C) and an engine compartment20as described in greater detail below. A front suspension22is connected to the frame. The tunnel18generally consists of one or more pieces of sheet metal bent to form an inverted U-shape. The tunnel18extends rearwardly along the longitudinal centerline61of the snowmobile10and is connected at the front to the engine compartment20. An engine24, which is schematically illustrated inFIG. 1, is carried by the engine compartment20of the frame16. A steering assembly (not indicated) is provided, in which two skis26are positioned at the forward end12of the snowmobile10and are attached to the front suspension22through a pair of front suspension assemblies28. As best seen inFIGS. 2 and 6, each front suspension assembly28includes a ski leg30, a pair of A-arms32and a shock absorber29for operatively connecting the respective skis26to a steering column34. Other types of front suspension assemblies28are contemplated, such as a swing-arm or a telescopic suspension. A steering device such as a handlebar36, positioned forward of a rider, is attached to the upper end of the steering column34to allow the rider to rotate the ski legs30and thus the skis26, in order to steer the snowmobile10.

An endless drive track65is positioned at the rear end14of the snowmobile10. The endless drive track65is disposed generally under the tunnel18, and is operatively connected to the engine24as will be described in greater detail below. The endless drive track65is driven to run about a rear suspension assembly42for propelling the snowmobile10. The rear suspension assembly42includes a pair of slide rails44in sliding contact with the endless drive track65. The rear suspension assembly42also includes one or more shock absorbers46which may further include a coil spring (not shown) surrounding the individual shock absorbers46. Suspension arms48and50are provided to attach the slide rails44to the frame16. One or more idler wheels52are also provided in the rear suspension assembly42.

At the front end12of the snowmobile10, fairings54enclose the engine24, thereby providing an external shell that not only protects the engine24, but can also be decorated to make the snowmobile10more aesthetically pleasing. Typically, the fairings54include a hood (not indicated) and one or more side panels which can be opened to allow access to the engine24when this is required, for example, for inspection or maintenance of the engine24. In the particular snowmobile10shown inFIG. 1, the side panels can be opened along a vertical axis to swing away from the snowmobile10. A windshield56may be connected to the fairings54near the front end12of the snowmobile10or directly to the handlebar36. The windshield56acts as a wind screen to lessen the force of the air on the rider while the snowmobile10is moving.

A straddle-type seat58is positioned atop the frame16. A rear portion of the seat58may include a storage compartment or can be used to accommodate a passenger seat (not indicated). Two footrests60are positioned on opposite sides of the snowmobile10below the seat58to accommodate the driver's feet.

Turning now toFIGS. 2 to 6, a power pack102for powering the endless drive track65will be described. For reasons described below, the power pack102has a power pack configuration which permits it to be disposed in any one of frames16A,16B and16C without having to be modified. The power pack102includes, but is not limited to, the engine24, a variable ratio belt transmission system, also known as a continuously variable transmission or CVT40, a reduction gearing78, and a countershaft100.

The engine24is a two cylinder, two-cycle internal combustion engine. It is contemplated that the engine24could be of any other type, such as a four-cycle internal combustion engine. The engine24is disposed in the engine compartment20and rests on vibration dampers104(FIG. 3) to reduce the transmission of vibrations from the engine24to the frame16. As best seen inFIGS. 4 and 5, the engine24has a plurality of air intakes106(one per cylinder) on a rear side thereof. An air intake manifold108is connected to the rear side of the engine24so as to fluidly communicate with the air intakes106. Two air intake controllers110, disposed vertically higher and rearwardly from the air intake manifold108, fluidly communicate with the air intake manifold108via air intake passages112. Although two air intake controllers110are illustrated, it is contemplated that only one air intake controller110could be used. The air intake controllers110each comprise a valve (not shown) which controls the flow of air to the engine24. It is contemplated that the air control devices could be in the form of a carburetor or a throttle body. A plurality of exhaust ports114(one per cylinder) are disposed on a front side of the engine24. An exhaust system (not shown) fluidly communicates with the engine24to exhaust the gases from the combustion process. The engine24comprises a crankshaft (not shown) which drives an output shaft25. The crankshaft and output shaft25are coaxial and rotate about a horizontally disposed axis that extends generally transversely to the longitudinal centerline61of the snowmobile10. It is contemplated that the crankshaft and output shaft25could be offset from one another. It is also contemplated that the crankshaft and the output shaft25could be integrally formed as a single shaft. As would be known by those skilled in the art, the engine24includes other systems, such as the fuel and electrical systems, but these have not been illustrated or described herein for simplicity.

Turning now toFIGS. 2 to 6and13, the power pack configuration of the power pack102will be described. As can be seen inFIGS. 2 and 6, the CVT40is disposed on a first side of the engine24and includes a driving pulley80coupled to rotate with the output shaft25of the engine24and a driven pulley88coupled to one end of a transversely mounted countershaft100. The countershaft100is supported in the engine compartment20through bearings. As can be seen, the countershaft100traverses the width of the engine compartment20. As best seen inFIG. 5, the countershaft is disposed rearwardly of the engine24, vertically higher than the air intake openings106, and forwardly of the air intake controllers110. The countershaft100is also disposed vertically higher than the tunnel18and a central axis of the countershaft100(the countershaft axis) is generally vertically aligned with a top portion of the engine24. In this position of the countershaft100, the driven pulley88is in proximity to the driving pulley80which ensures a good torque transfer from the driving pulley80to the driven pulley88. Also, by locating the countershaft100in this position and by appropriately sizing the driven pulley88, the lowermost portion of the driven pulley88is disposed vertically higher than the tunnel18such that regardless of in which frame16A,16B, or16C the power pack102is disposed, the driven pulley88will not interfere with the corresponding tunnel18A,18B, or18C. Therefore, the power pack102can be used in any one of frames16A,16B, and16C without having to modify the power pack configuration and without having to move the engine laterally with respect to the longitudinal centerline61, thus maintaining the transverse mass centralization of the snowmobile10. As can be seen inFIGS. 6 and 13, a distance X between the centerline61and an end of the engine24in frames16A and16B remains the same, and would be the same in frame16C. Also since the power pack102can remain the same regardless of which frame16A,16B, or16C is used, the frames16A,16B, and16C can have engine compartments20that have the same configuration.

The driving pulley80of the CVT40is coupled to rotate with the output shaft25of the engine24and includes a pair of opposed frustoconical belt drive sheaves (one fixed sheave and one moving sheave) between which the drive belt (not shown) is located. The sheaves are biased apart, and the driving pulley80incorporates a centrifugally operated mechanism that acts to urge the moving sheave towards the fixed sheave with a force that increases with increasing output shaft speed so that as the engine speed increases, the reduction ratio of the CVT40decreases. The driven pulley88is coupled to rotate with the countershaft100and includes a pair of frustoconical belt drive sheaves between which the drive belt is located. The driven pulley88reacts to the torque from the endless drive track65by separation of its sheaves which allows the drive belt to engage the driven pulley88at a diameter that is progressively reduced as the torque increases or that is progressively increased as the torque decreases. When the driving pulley80increases its diameter, the driven pulley88decreases its effective diameter and vice versa, thus keeping the drive belt in tension.

A reduction gearing78is disposed on a second side of the engine24which is opposite the side on which the CVT40is disposed. The end of the countershaft100which is opposite the end on which the driven pulley88is disposed is connected to an input member of the reduction gearing78. The input member of the reduction gearing78consists of a small sprocket connected to the countershaft100. An output member of the reduction gearing78is connected to a front drive axle90. The output member consists of sprocket which is larger than the sprocket of the input member and is connected to the drive axle90. The output member is driven via a chain by the input member. It is also contemplated that the output member could be driven via gears by the input member. The input member, the output member, and the chain are enclosed within the housing of the reduction gearing78. The front drive axle90is disposed in the tunnel18and carries sprocket wheels (not shown)) that form a driving connection with the endless drive track65. The output shaft25, the countershaft100, and the front drive axle90are arranged such that the countershaft100is disposed rearwardly of the output shaft25and forwardly of the front drive axle90.

In this particular example, the driving pulley80rotates at the same speed as the output shaft25of the engine24. The speed of rotation of the countershaft100is determined in accordance with the instantaneous ratio of the CVT40. The drive axle90rotates at a lower speed than the countershaft100since the reduction gearing78has a reduction ratio.

As previously mentioned, since the power pack102has a power pack configuration in which the driven pulley88of the CVT40does not interfere with the tunnel18, different members of the family of snowmobiles10can be designed with different tunnel widths without having to move the power pack102transversely as was the case in the prior art. Since the power pack102does not have to be moved from one member of the family to the other, then the same configuration of engine compartment can be used by all members of the family. This advantageously reduces the manufacturing cost as would be understood by those skilled in the art. The configuration of engine compartment20will now be described with respect toFIGS. 2 to 6and more particularlyFIGS. 10 to 12, but the same engine compartment20also appears in the other figures. It should be noted that portions of the engine compartment have been removed fromFIGS. 2 to 6such that portions of the power pack102can be seen more clearly. It should be understood that the configuration of the engine compartment20described herein is only one possible configuration and that other configurations for engine compartment20are contemplated, but that regardless of the configuration selected, since the power pack102does not have to be moved transversely as the tunnel18is widened, a particular configuration could be used by all members of the family of snowmobile.

The lower portion of the engine compartment20has a front sub-frame116behind which are connected a right side wall118, a left side wall120, and an engine compartment bottom122. The side walls118,120are generally vertical and generally parallel to the longitudinal centerline61. The engine compartment bottom122is generally horizontal and extends transversely between and beyond the side walls118,120. The length by which the engine compartment bottom122extends beyond the side walls118,120is determined by features of the snowmobile10that need to be attached to engine compartment20. Although the engine compartment bottom122is shown as being different from one frame16to the other, it could actually be the same in all of the frames16, therefore this change is considered to be one of the minor variations contemplated and as such the engine compartments20are still considered to have the same configuration (see the definition of “same” above). The front sub-frame116has a pair of inverted generally V-shaped suspension mounting brackets124, one on each side thereof, to receive the pair of front suspension assemblies28as seen inFIGS. 2 and 6. It is contemplated that the suspension mounting brackets124could be modified to accommodate a different type of front suspension assemblies28from one member of the family of snowmobiles to the other. A bulkhead126has one side connected to a rear portion of right side wall118, the other side connected to a rear portion of the left side wall120, and a bottom connected to a rear portion of the engine compartment bottom122. A countershaft support bracket128is connected to a left side of the bulkhead126. The countershaft support bracket128has an opening130to receive and support a left end portion of the countershaft100. The front sub-frame116, the right and left side walls118,120, the engine compartment bottom122, the bulkhead126, and the countershaft support bracket128are preferably made from bent sheet metal or by casting, and are preferably connected to each other by fasteners such as rivets or bolts. As seen inFIGS. 2 to 6, the engine24is disposed longitudinally between the front sub-frame116and the bulkhead126, and transversely between the right and left side walls118,120such that the mass of the power pack102is transversely balanced.

The upper portion of the engine compartment20has a front cross-member132which extends transversely from one suspension mounting bracket124to the other. A pair of front braces134extend upwardly and rearwardly from the pair of suspension mounting brackets124to a steering bracket136. The steering bracket136is aligned with the longitudinal centerline61of the snowmobile10and has an opening therein to receive the steering column34. A rear cross-member138extends transversely from the upper end of the countershaft support bracket128to the reduction gearing78. A pair of columns140extend from the ends of the rear cross-member138to the steering bracket136. A pair of rear braces142extend rearwardly from the steering bracket to a top of the tunnel18. The front braces134, the columns140, and rear braces142form together a pyramidal-like structure which enhances the torsional and structural rigidity of the frame16. The front cross-member132, the front braces134, the rear cross-member138, the columns140, and the rear braces142are preferably made of aluminum tubing, but other structures and materials are also contemplated.

A first member of the family of snowmobiles has the features of the snowmobile10described above, a power pack configuration corresponding to the configuration of power pack102described above, and a frame16A. The frame16A has an engine compartment configuration corresponding to the engine compartment20described above and a tunnel18A disposed rearward of the engine compartment20. The frame16A will now be described with respect toFIGS. 2 to 9.

As best seen inFIG. 7, the tunnel18A of frame16A is made of three parts. The tunnel18A has a central tunnel portion144A, a right side tunnel portion146A, and a left side tunnel portion148A. The central tunnel portion144A is disposed generally horizontally and has an integrated heat exchanger150A which is used to cool the engine coolant. It is contemplated that the heat exchanger150A could be fastened to a bottom of the central tunnel portion144A or could be disposed elsewhere on the frame16A. The front portion of the central tunnel portion144is connected to a rear portion of the bulkhead126via fasteners. It is contemplated that the front portion of the central tunnel portion144could alternatively be connected to a rear portion of the bulkhead126by welding. The right and left side tunnel portions146A,148A are disposed generally vertically and each have a footrest60extending outwardly from a bottom portion thereof. The right side tunnel portion146A has a right side horizontal flange152A which connects the right side tunnel portion146A to a right side of the central tunnel portion144A. Similarly, the left side tunnel portion148A has a left side horizontal flange154A that connects the left side tunnel portion148A to a left side of the central tunnel portion144A. The right and left side horizontal flanges152A,154A are fastened to the central frame portion144A at a certain distance from the longitudinal centerline61of the snowmobile10such that the tunnel18A has a tunnel width W1(FIG. 6) which can accommodate the width of the endless track65for which the frame16A is designed. The tunnel width is measured directly below the central tunnel portion144perpendicularly to the longitudinal centerline61from the inside of the right tunnel side portion146to the inside of the left tunnel side portion148. In the event that the tunnel18has a non uniform width along its length, the tunnel width is to be measured directly above the front drive axle90. For exemplary purposes only and to provide a reference with respect to the other tunnels18B and18C, the tunnel18A could accommodate an endless track65having a width of 50.8 cm (20 inches). Since the tunnel18A has a width W1which is greater than the width of the engine compartment20, right and left spacers156A and158A, respectively, are provided in order to connect the tunnel18A to the sides of the engine compartment20. The right spacer156A is inserted between the right tunnel side portion146A and a right side of the engine compartment20and is fastened to each of them. Similarly, the left spacer158A is inserted between the left tunnel side portion148A and a left side of the engine compartment20and is fastened to each of them.

Turning now toFIG. 8, the right spacer156A will now be described. The right spacer156A has a central spacer portion160, an inner flange162, and an outer flange164. The width of the central spacer portion160is selected such that the width of the right spacer156A corresponds to the distance between the right tunnel side portion146A and the right side of the engine compartment20. The inner flange162provides fastener openings166to receive the fasteners which fasten the right spacer156A to the right side of the engine compartment20. The outer flange164provides fastener openings168to receive the fasteners which fasten the right spacer156A to the right side tunnel portion146A. The profiles of the central spacer portion160, the inner flange162, and the outer flange164are selected to correspond to the profiles of the portions of the engine compartment20and right side tunnel portion146A to which the right spacer156A is fastened. An upper flange170is provided at a top of the central spacer portion160to provide fastener openings172to receive the fasteners which fasten the right spacer156A to the right side horizontal flange152A. An L-shaped bracket174is provided at a bottom of the central spacer portion160to provide additional fastener openings176to receive additional fasteners which fasten the right spacer156A to the right side of the engine compartment20and to provide fastener openings178to receive fasteners which fasten the right spacer156A to the portion of the engine compartment bottom122which extends beyond the right side wall118of the engine compartment20. This embodiment of the right spacer156A is preferred as it solidly connects the right side tunnel portion146A and the right side of the engine compartment20and completely fills the space therebetween. However, other constructions of the right spacer156A are contemplated. For example, the right spacer156A could consist of one or more brackets which link the right side tunnel portion146A and the right side of the engine compartment20.

FIG. 9illustrates the left spacer158A. The left spacer158A is substantially a mirror image of the right spacer156A. Therefore, like elements have been labeled with the same reference numerals and the left spacer158A will not be described in detail. It should be understood that the description of the right spacer156A when applied to the left spacer158A would refer to the elements disposed on the left side of the frame16A (i.e. the left side tunnel portion148A, the left side of the engine compartment20, etc.).

A second member of the family of snowmobiles has the features of the snowmobile10described above, a power pack configuration corresponding to the configuration of power pack102described above, and a frame16B. The frame16B has an engine compartment configuration corresponding to the engine compartment20described above and a tunnel18B disposed rearward of the engine compartment20. The frame16B will now be described with respect toFIGS. 10 to 12.

The tunnel18B of frame16B is also made of three parts. The tunnel18B has a central tunnel portion144B, a right side tunnel portion146B, and a left side tunnel portion148B which have the same physical characteristics as the central tunnel portion144A, the right side tunnel portion146A, and the left side tunnel portion148A, and will therefore not be described again. The main difference between the tunnel18B and the tunnel18A, is that the right and left side horizontal flanges152B,154B of the right and left side tunnel portions146B and148B are fastened to the central frame portion144B at a shorter distance from the longitudinal centerline61of the snowmobile10than in tunnel18A. Therefore, the tunnel18B has a tunnel width W2(FIG. 10) which can accommodate the width of the endless track65for which the frame16B is designed, which is less than the width of the endless track65for which the frame16A is designed. For exemplary purposes only and to provide a reference with respect to the other tunnels18A and18C, the tunnel18B could accommodate an endless track65having a width of 38.1 cm (15 inches). Since the tunnel18B has a width W2which substantially the same as the width of the engine compartment20, the right and left side tunnel portions146B and148B are directly fastened to their corresponding sides of the engine compartment20. Thus, no spacers are required in the construction of frame16B.

A third member of the family of snowmobiles has the features of the snowmobile10described above, a power pack configuration corresponding to the configuration of power pack102described above, and a frame16C. The frame16C has an engine compartment configuration corresponding to the engine compartment20described above and a tunnel18C disposed rearward of the engine compartment20. The frame16C will now be described with respect toFIGS. 13 to 19.

The tunnel18C of frame16C is also made of three parts. The tunnel18C has a central tunnel portion144C, a right side tunnel portion146C, and a left side tunnel portion148C which have the same physical characteristics as the central tunnel portion144A, the right side tunnel portion146A, and the left side tunnel portion148A, and will therefore not be described again. The main difference between the tunnel18C and the tunnel18A, is that the right and left side horizontal flanges152C,154C of the right and left side tunnel portions146C and148C are fastened to the central frame portion144C at a greater distance from the longitudinal centerline61of the snowmobile10than in tunnel18A. Therefore, the tunnel18C has a tunnel width W3(FIG. 14) which can accommodate the width of the endless track65for which the frame16C is designed, which is greater than the width of the endless track65for which the frame16A is designed. For exemplary purposes only and to provide a reference with respect to the other tunnels18A and18B, the tunnel18C could accommodate an endless track65having a width of 61 cm (24 inches). Since the tunnel18C has a width W3which is greater than the width of the engine compartment20, right and left spacers156C and158C, respectively, are provided in order to connect the tunnel18C to the sides of the engine compartment20. The right spacer156C is inserted between the right tunnel side portion146C and a right side of the engine compartment20and is fastened to each of them. Similarly, the left spacer158C is inserted between the left tunnel side portion148C and a left side of the engine compartment20and is fastened to each of them.

FIGS. 18 and 19illustrate the right and left spacers156C and158C respectively. The spacers156C and158C have substantially the same physical characteristics as the spacers156A and158A respectively. The main difference is that the spacers156C and158C are wider than the spacers156A and158A since the distance between the right and left tunnel side portions146C and148C and the engine compartment20in frame16C is greater than a corresponding distance in frame16A. Therefore, like elements have been labeled with the same reference numerals and the spacers156C and158C will not be described in detail.

Although not described, it should be understood that other members of the family of snowmobiles are contemplated which could be designed with other tunnel widths by applying the teachings of the present application.

As should be apparent from the above description, the tunnels18A,18B, and18C can be manufactured by using three common parts (central portion144, right side tunnel portion146, and left side tunnel portion148). The different tunnel widths are obtained by connecting the tunnel side portions146,148to the central tunnel portion144closer or farther away from the longitudinal centerline61to obtain the desired width. Appropriately sized spacers156,158are then inserted, as necessary, between the tunnel18and the sides of the engine compartment20to complete the assembly of the frame16. As would be understood by those skilled in the art, having common parts is advantageous as it reduces manufacturing cost. It is contemplated that the tunnel18of each frame16could also be made of two or more than three parts. It is also contemplated that each tunnel18A,18B, and18C could each be made of a single part each having a different tunnel width.