Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02523999 2005-10-21
SNOWMOBILE WITH BEVELED TUNNEL
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is the first application filed for the present
invention.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a
snowmobile and, more particularly, to a snowmobile tunnel.
BACKGROUND OF THE INVENTION
[0003] Prior-art snowmobile tunnels conventionally have a
"square profile", meaning that side portions 18b of the
tunnel 18 are substantially perpendicular to a top portion
18a, or top surface, of the tunnel, as illustrated in FIG.
1. In other words, the side portions 18b of the tunnel
depend downwardly from side edges 18c of the top portion
18a in a generally orthogonal manner. The side portions
are spaced apart to accommodate an endless drive track 38
and to provide mounting points for the rear suspension 42,
as is known in the art. The side portions typically
support footrests 60 that help position the rider in a
comfortable posture on a seat 58 while providing adequate
ground clearance, as is also known in the art.
[000] FIG. 1 shows a snowmobile having a standard 15-inch
track. when aggressively cornering, however, the side
edges 18c tend to dig into the legs 4 of the rider 2,
causing discomfort and thus rendering the entire driving
experience less pleasant.
[0005] For a wide-tracked snowmobile, as depicted in FIG.
2, the seat 58 is often made to be as wide as the tunnel
18, which makes it quite uncomfortable for a rider to
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straddle the seat. Furthermore, with an extra wide seat,
it is difficult to lean into a turn without having to lift
one's foot off the outside footrest.
[0006] One solution to the problems associated with extra-
wide seats has been to place a standard-size seat, i . e. a
seat designed for a standard 15-inch tunnel, on a tunnel
that is designed for a 20- or 24-inch wide track. However,
during cornering, the side edges of the standard-size
tunnel tend to dig into the rider's legs, causing
discomfort and, furthermore, diminishing control of the
snowmobile.
[0007] Therefore, it would be highly desirable to provide
a snowmobile tunnel that improves rider comfort while
enabling the rider to maintain good control of the
snowmobile.
SUM~2ARY OF THE INVENTION
[0008] It is an object of the present invention to provide
a snowmobile tunnel that improves rider comfort while
enabling the rider to maintain good control of the
snowmobile, especially when cornering aggressively and/or
when riding a wide-track snowmobile.
[0009] In accordance with one aspect of the present
invention, a snowmobile includes a frame including a
tunnel, an engine disposed on the frame, a drive track
disposed below and supported by the tunnel and operatively
connected to the engine for propulsion of the snowmobile, a
straddle seat disposed on the tunnel above the drive track
and rearward of the engine, and two steerable skis disposed
on the frame, each via a front suspension. The tunnel
includes a top portion for supporting a seat, and a pair of
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side walls depending downwardly from side edges of the top
portion, the side walls being spaced apart to accommodate
an endless drive track, the side walls having beveled upper
portions and substantially vertical lower portions, the
upper beveled portions connecting the top portion of the
tunnel to the substantially vertical lower portions.
[0010] In one embodiment, the seat has beveled sides to
further increase rider comfort.
(0011] In another embodiment, the beveled portion has a
bevel angle of 20 to 24 degrees from the vertical.
(0012] In accordance with yet another aspect of the
present invention, a snowmobile includes a frame including
a tunnel, an engine disposed on the frame, a drive track
disposed below and supported by the tunnel and operatively
connected to the engine for propulsion of the snowmobile, a
straddle seat disposed on the tunnel above the drive track
and rearward of the engine, and two steerable skis disposed
on the frame, each via a front suspension. The tunnel
includes a top surface for supporting a seat, a pair of
beveled surfaces that connect to and flare outwardly and
downwardly from side edges of the top surface, and a pair
of spaced-apart, substantially vertical side surfaces, each
side surface being connected to and depending downwardly
from a respective beveled surface for supporting a
footrest.
[0013] In one embodiment, the seat has beveled sides to
further increase rider comfort.
[0014] In another embodiment, the beveled surfaces have
bevel angles of 21 to 23 degrees from the vertical.
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[0015] In another embodiment, the top surface has a width
equal to 88% to 92% of a width of the tunnel and a width of
a horizontal projection of each beveled surface is equal to
4% to 6% of the width of the tunnel.
[0016] In yet another embodiment, a vertical projection of
each beveled surface has a height equal to 27%-29% of a
height of each vertical side wall.
[0017] The beveled tunnel improves rider comfort, as
compared with prior-art, square-profile tunnels that tend
to dig into the rider's legs when cornering aggressively on
a snowmobile with a standard (e. g. 15-inch) track or when
straddling wide-tracked snowmobiles, e.g. snowmobiles with
20-inch or 24 inch tracks. The beveled tunnel enhances
rider comfort while permitting transverse structural
members to be connected to the side walls beneath the
beveled portions. Since the beveled tunnel design does not
require repackaging or re-engineering of the rear
suspension or the endless track drive, the beveled tunnel
can be readily integrated into current snowmobile designs.
[0018] 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
[0019] 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:
[0020] FIG. 1 is a rear view of a prior-art snowmobile
having a standard-size, conventional, square-profile
tunnel;
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[0021] FIG. 2 is a rear view of a wide-track prior-art
snowmobile, depicting a rider uncomfortably straddling a
wide seat mounted on a wide tunnel;
[0022] FIG. 3 is a side view of a snowmobile capable of
incorporating a beveled tunnel in accordance with
embodiments of the present invention;
[0023] FIG. 4 is a rear view of a snowmobile having a
beveled tunnel in accordance with a preferred embodiment of
the present invention; and
[0024] FIG. 5 is a rear view of a rider on a snowmobile
having a beveled tunnel in accordance with embodiments of
the present invention;
[0025] FIG. 6 is an isometric perspective view of an
endless drive track and associated rear suspension,
depicted with a beveled tunnel in accordance with the
preferred embodiment of the present invention, viewed from
a rear left side of the snowmobile; and
[0026] FIG. 7 is a rear view of the beveled tunnel shown
in FIG. 6; and
[0027] FIG. 8 is a side elevational view of the drive
track, rear suspension and beveled tunnel shown in FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] Referring now to FIG. 3, a snowmobile incorporating
an embodiment of the present invention is designated
generally by references 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.
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[0029] The snowmobile 10 includes a forward end 12 and a
rearward end 14 which are defined consistently with a
travel direction of the vehicle. The snowmobile 10 has a
frame or chassis 16 which includes a beveled tunnel 100 in
accordance with embodiments of the present invention, and
which will be described in detail below, an engine cradle
portion 20 and a front suspension assembly portion 22. An
engine 24, which is schematically illustrated in FIG. 3, is
carried by the engine cradle portion 20 of the frame 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 frame 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 the
beveled tunnel 100, being connected operatively to the
engine 24 through a belt transmission system 40 which is
schematically illustrated by broken lines in FIG. 3. 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
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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 frame
(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
shown in FIG. 3, 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 frame 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
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transmission system 40 for transmitting torque to the
endless drive track 38 for propulsion of the snowmobile 10.
[0033] A straddle-type seat 58 is positioned atop the
frame 16 and extends from the rear end 14 of the snowmobile
to the fairings 54. A rear portion of the seat 58 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
seat 58 to accommodate the driver's feet.
[0034] FIG. 4 is a rear view of a snowmobile having a
beveled tunnel 100 in accordance with a preferred
embodiment of the present invention. As illustrated in
FIG. 4, the beveled tunnel 100 has a top portion 102 for
supporting a seat 120. The tunnel 100 also includes a pair
of side walls 105 depending downwardly from side edges 104
of the top portion 102, the side walls 105 being spaced
apart to accommodate an endless drive track 38, the side
walls having beveled upper portions 106 and substantially
vertical lower portions 108, the upper beveled portions 106
connecting the top portion 102 of the tunnel 100 to the
substantially vertical lower portions 108.
[0035] In the preferred embodiment, as illustrated in FIG.
4, the top portion 102 is a generally flat top surface upon
which the seat 120 is mounted. In the preferred
embodiment, the upper beveled portions 106 are a pair of
beveled surfaces that connect to and flare outwardly and
downwardly from the side edges 104 of the top surface, i.e.
top portion 102. In the preferred embodiment, the
substantially vertical lower portions 108 are a pair of
spaced-apart, substantially vertical side surfaces, each
side surface being connected to and depending downwardly
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from a respective beveled surface for supporting a footrest
60, as shown in FIG. 4.
[0036] As further illustrated in FIG. 4, the beveled
surfaces (beveled portions 106) preferably have symmetrical
bevel angles f3 of 20° to 24°. More preferably, the bevel
angle i~ is 21° to 23° and, most preferably, f~ = 22° .
[0037] As further illustrated in FIG. 4, the seat 120 can
also be beveled to further enhance rider comfort. The seat
120 can be beveled either at the same angle as the beveled
portions 106 or at a different angle. As shown in FIG. 4,
a molded plastic understructure 122 of the seat 120 is
preferably beveled at the same bevel angle f~ while a padded
upper portion of the seat is angled at a more shallow angle
e.
[0038] As further illustrated in FIG. 4, the beveled
tunnel 100 can be readily integrated into most snowmobiles
without having to repackage or re-engineer the rear
suspension 42 and endless drive track 38. The position and
layout of rear suspension components such as, for example,
the shock absorber 46, coil spring 47, and idler wheels 52,
need not be modified or relocated. Similarly, any
transversely mounted shafts used for connecting the rear
suspension 42 to the tunnel, e.g. the transverse shaft 110
used to anchor the top end of the shock 46, is preferably
mounted to the substantially vertical lower portions 108,
i.e. beneath the beveled portions 106. Since the beveled
tunnel can be readily used on a snowmobile without
repackaging the components of the rear suspension, the
tunnel therefore provides a practical and useful
improvement in snowmobile tunnel technology.
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[0039] FIG. 4 illustrates, by way of example only, a
snowmobile having a 15-inch track in which the seat 120 on
the beveled tunnel 100 preferably has a width equal to 90-
95% of a width of the tunnel, although this proportion can
of course be varied beyond this range. Tt should be
expressly understood that the beveled tunnel can be applied
to snowmobiles having any track size, including wide-track
snowmobiles having 20-inch or 24-inch tracks and therefore
the ranges, percentages and ratios mentioned herein are
merely meant to serve as an example, and are therefore not
intended to be limiting in any manner whatsoever. In the
example shown in FIG. 4 (where the tunnel is sized to
accommodate a standard 15-inch track), the top portion 102
preferably has a width that is between 85% and 95% of the
width of the tunnel, whereby a horizontal projection of
each beveled portion correspondingly has a width between
2.5% and 7.5% of the width of the tunnel. More preferably,
and again by way of example only, the width of the top
portion is equal to 88% to 92% of the width of the tunnel
and the width of the horizontal projection of each beveled
portion is equal to 4% to 6% of the width of the tunnel.
Most preferably, and again by way of example only, the
width of the top portion is equal to 90% of the width of
the tunnel and the width of the horizontal projection of
each beveled portion is equal to 05 of the width of the
tunnel.
[0040] Preferably, and again by way of example only, a
vertical projection of each beveled portion has a height
equal to 26-30% (and more preferably 28%) of a height of
each lower vertical portion. For greater certainty, it
bears repeating that the foregoing ranges, percentages and
ratios are presented solely for the purposes of example to
illustrate the best mode known to the applicants) of
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implementing the invention on a snowmobile tunnel designed
for a standard-size 15-inch track, and therefore should not
be construed in any way as delimiting the scope of the
invention.
[0041] As further illustrated in FIG. 4, the endless drive
track 38 has a plurality of lugs 39 extending outwardly
from the endless drive track for increasing traction in the
snow, as is known in the art. Each of the lugs 39 has a
base attached to the outer surface of the track 38 and a
tip extending away from the base. The lugs are beveled
toward the tip, as shown in FIG. 4. Preferably, at least a
portion of each lug extends above a horizontal plane 116
that demarcates the lowest point of the beveled portion 106
of the tunnel 100, i.e. where the beveled portion 106 of
the tunnel meets the lower vertical portion 108 of the
tunnel. Preferably, the lugs 39 are beveled at the same
bevel angle (e.g. f3 - 22°) as the beveled portion 106 in
order to enable compact but interference-free packaging of
the drive track 38 under the beveled tunnel 100.
[0042] As further illustrated in FIG. 4, a front drive
axle 70 (which is operatively connected to the transmission
system 40 in a manner well known in the art) is, in turn,
rotatably mounted to the vertical side surfaces 108 (i.e.
the substantially vertical side portions). In other words,
the front drive axle 70 is mounted beneath the horizontal
plane 116 defined by where the beveled surfaces and
vertical side surfaces connect. As further shown in FIG.
4, a drive sprocket 72 is driven by the front drive axle 70
to drive the endless drive track 38, as is well known in
the art. Preferably, the drive sprocket 72 rotates
entirely below the horizontal plane 116 that is defined by
where the beveled surfaces and vertical side surfaces
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connect. In other words, as the drive sprocket 72 rotates,
its outermost periphery remains beneath the horizontal
plane 116.
[0043] As shown in FIG. 5, the beveled tunnel 100 enhances
rider comfort. Compared to the "square-profile" prior-art
tunnel shown in FIG. 2, the beveled tunnel shown in FIG. 5
greatly reduces the discomfort on the legs 4 of the rider
2. As shown in FIG. 5, the bevel angles of the beveled
portions 106 and of the seat 120 are chosen to optimize
comfort without sacrificing vehicle control. Accordingly,
as will be appreciated by those of ordinary skill in the
art, the bevel angles of the beveled portion 106 and of the
seat 120 can be varied for different types of snowmobiles
and to accommodate the varying tastes of different types of
riders. As will be further appreciated by those of
ordinary skill in the art, the design of a narrow, beveled
seat 120 might require the footrests 60 to be raised since
the rider who straddles the narrow, beveled seat is seated
slightly more upright than in the traditionally seated
posture.
[0044] FIG. 6 is an isometric perspective view of an
endless drive track 38 and associated rear suspension 42,
depicted with a beveled tunnel 100 in accordance with the
preferred embodiment of the present invention, viewed from
a rear left side of the snowmobile. As shown in FIG. 6,
forward mounting points 112 and rearward mounting points
114 can be provided in the beveled portion 106 to enable
the seat 120 to be mounted to the tunnel 100.
[0045] FIG. 7 is a rear view of the beveled tunnel 100.
The beveled tunnel 100 is preferably manufactured from
aluminum or a suitable aluminum alloy, although other high-
stiffness, high-strength, lightweight materials could be
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substituted. The beveled tunnel 100 can be manufactured by
applying known metal-bending techniques and by riveting
other aluminum components to the tunnel, such as the
footrests 60. The footrests are preferably attached to the
substantially vertical lower portions (side surfaces) 108
as shown in FIG. 7.
[0046] FIG. 8 is a side elevational view of the drive
track 38, rear suspension 42 and beveled tunnel 100. As
shown in FIG. 8, the rear suspension 42 includes front and
rear shocks 46 and associated coil springs 47. Slide rails
44 and idler wheels 52 guide the endless drive track 38
around the rear suspension, as is known in the art.
Although the beveled tunnel 100 enhances rider comfort,
ground clearance and the degree to which the tunnel
partially enshrouds the top of the rear suspension remains
substantially the same as in prior-art snowmobiles, as
shown in FIG. 8. Therefore, the beveled tunnel 100
improves rider comfort without detrimentally affecting the
layout and configuration of the rear components of the
snowmobile.
(0047] 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.
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