Note: Descriptions are shown in the official language in which they were submitted.
CA 02350264 2001-06-12
FRAME CONSTRUCTION FOR A VEHICLE
1. Field of the Invention
[0001 ] The present invention relates to the construction of vehicles such as
snowmobiles,
all terrain vehicles ("ATVs"), and other similar vehicles. More specifically,
the present invention
concerns the construction of a frame and related structural elements that
enhance the ruggedness
and ability of such vehicles to operate across a wide variety of different
terrains and under a wide
variety of conditions. In addition, the present invention concerns the design
and construction of a
frame for snowmobiles, ATVs, and related vehicles that facilitate the
construction of such
vehicles with an improved rider positioning.
2. Description of Related Art and General Background
[0002] Snowmobiles, ATVs, and related vehicles (hereinafter, "recreational
vehicles,"
although the appellation should not be construed to be limited only to the
vehicles or type of
vehicles described herein) often function under similar operating conditions.
Despite this,
snowmobiles, ATVs, and other recreational vehicles often do not share a common
design
approach or a commonality of components. This is due, in large part, to the
different stresses and
strains (mainly at the extremes) that the different vehicles experience during
routine operation.
[0003] Specifically, snowmobiles are designed with frame assemblies and
suspensions
that easily absorb the shock of obstacles encountered on groomed trails and in
deep snow. They
are also designed to handle the forces generated when the snowmobile is driven
aggressively
(e.g., under racing conditions). In addition, their frame assemblies are
designed to provide
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optimum steering and performance in snow, whether on groomed snowmobile trails
(packed
snow) or in ungroomed, off trail areas (powder or natural snow).
[0004] ATVs, on the other hand, are designed with suspensions and frame
assemblies that
are expected to absorb the type of momentarily intense forces associated with
more rugged
terrain, specifically of the type encountered in forests and woodland
environments. In addition,
an ATV frame is designed to withstand forces associated with significant
torsional stresses that
are typical when an ATV straddles large objects or when the wheels are
disposed at different
elevations because of the extreme terrain in which the ATV often operates.
[0005] It should be kept in mind that the design parameters of the frame
assemblies for
these two vehicles are also different. In a snowmobile, the frame at the rear
of the vehicle is only
about 15 inches wide. This is sufficient to cover the endless track that
propels the vehicle and to
provide a seating area for the driver. The narrow width, however, imposes
certain design
restrictions on the vehicle. ATVs, on the other hand, are designed with a
significantly wider
base, which is typically 50 inches or more. This width also imposes certain
design restrictions on
the ATV.
[0006] Snowmobiles and ATVs are also designed with different centers of
gravity. In the
typical snowmobile, the center of gravity is very low. This assists the
snowmobile rider when he
or she is on a slope or in a turn because the snowmobile will naturally resist
the tendency to lean
or tip. ATVs, on the other hand, like off road trucks and the like, are
expected to traverse taller
objects. Accordingly, their frames are designed so that the engine and seating
area is further
from the ground than a snowmobile. Thus, ATVs have higher centers of gravity.
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[0007] Naturally, since both vehicles are designed with off road use in mind,
there are
similarities between the two. Both are provided with rugged frames. Moreover,
both are
provided with strong suspensions. Despite this, there have been few vehicles
designed that
capitalize on these similarities.
[0008] Recognizing this basic similarity between the two vehicles, some after-
market
designers have developed kits that permit snowmobiles to be converted to ATVs
and vice-versa.
However, such kits are limited in their effectiveness because the two vehicles
are so completely
different from one another in their basic designs. The resulting, converted
vehicles suffer from
drawbacks that are associated with the purpose for which the primary vehicle
was designed. For
example, a snowmobile converted to an ATV is not expected to be able to
traverse the same type
of terrain as a pure ATV. Similarly, an ATV that has been converted to a
snowmobile is not
expected to be able to traverse the same terrain that a pure snowmobile can.
[0009] Partly due to the consumer's use of snowmobiles in the winter and ATVs
in the
summer, the evolution of both snowmobiles and ATVs has converged in recent
years. Also, in
recent years, designers have begun to apply the same basic design concepts to
both vehicle types.
What has resulted is a recognition that vehicles may be designed that
incorporate many of the
same structural elements and follow very similar design approaches.
[0010] The basis for the present invention stems from this basic recognition.
SUMMARY OF THE INVENTION
[0011] It is, therefore, an object of the present invention to provide a frame
assembly with
a tunnel, an engine cradle disposed forward of the tunnel and connected
thereto, and a sub-frame
disposed forward of the engine cradle and connected thereto. The frame
assembly further
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includes a forward support assembly extending upwardly from the subframe, an
upper column
extending upwardly from the engine cradle to connect with the forward support
assembly, and a
rear brace assembly extending upwardly from the tunnel to connect with the
forward support
assembly and the upper column.
[0012] It is another object of the present invention to provide a frame
assembly wherein
the forward support assembly, the upper column, and the rear brace assembly
connect at an apex
above the upper column.
[0013] Another object of the present invention is to provide a frame assembly
where the
forward support assembly and the rear brace assembly form a pyramidal
construction.
[0014] A further object of the present invention is to provide a frame
assembly further
including a steering bracket connected at the apex for supporting a steering
shaft at its upper end.
In an alternate embodiment, the steering bracket may include a plurality of
pairs of holes for
positioning of the steering shaft in a plurality of positions.
[0015] One other object of the present invention is to provide a frame
assembly that also
includes an engine disposed in the engine cradle and an endless track
operatively connected to the
engine and disposed beneath the tunnel for propulsion. In this embodiment, a
pair of skis are
operatively connected to a steering device for steering.
[0016] Still another object of the present invention is to provide a frame
assembly with an
engine disposed in the engine cradle and a rear wheel operatively connected to
the engine and
disposed beneath the tunnel for propulsion. In this embodiment, two front
wheels operatively
connected to a steering device for steering.
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[0017] It is yet another object of the present invention to provide a frame
assembly for a
vehicle that includes a tunnel and an engine cradle adapted to receive an
engine therein. A rear
brace assembly is attached to the tunnel at a point between its front and rear
ends and extends
upwardly therefrom. A forward support assembly is attached to the rear brace
assembly and
extends forwardly and downwardly therefrom. In a further variation of this
frame assembly, the
rear brace assembly comprises a left and a right leg and the forward support
assembly comprises
a left and a right leg. The left and right legs of the rear brace assembly and
the forward support
assembly connect to one another at an apex to form a pyramidal structure above
the tunnel and
engine cradle.
[0018] Still other objects of the present invention will be made apparent by
the discussion
that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention will be more fully described in conjunction with the
following
drawings wherein:
[0020] Figure 1 is a side-view schematic illustration of a prior art
snowmobile, showing
the prior art positioning of a rider thereon;
[0021 ] Figure 2 is a side view illustration of the exterior of a snowmobile
constructed
according to the teachings of the present invention, also showing the
positioning of a rider
thereon;
[0022] Figure 3 is an overlay comparison between the a prior art snowmobile
(of the type
depicted in Figure 1) and a snowmobile constructed according to the teachings
of the present
CA 02350264 2001-06-12
invention (as shown in Figure 2), illustrating the difference in passenger
positioning, among other
features;
[0023] Figure 4 is an exploded view of a frame assembly representative of the
type of
construction typical of a snowmobile assembled according to the teachings of
the prior art
(specifically, the view illustrates the components of a 2000 model year Ski-
Doo~ MachTM Z
made by Bombardier Inc. of Montreal, Quebec, Canada);
[0024] Figure 5 is a side view schematic illustration of the snowmobile
illustrated in
Figure 2, with the fairings and external details removed to show some of the
internal components
of the snowmobile and their positional relationship to one another;
[0025] Figure 6 is a perspective illustration of a portion of the frame
assembly of the
present invention, specifically the portion disposed toward the rear of the
vehicle;
[0026] Figure 7 is a perspective illustration of a forward support frame,
which connects
with the portion of the frame assembly depicted in Figure 6;
[0027] Figure 8 is a front view illustration of an upper column of the frame
assembly
shown in Figure 6;
[0028] Figure 9 is a left side view illustration of the upper column depicted
in Figure 8;
[0029] Figure 10 is a right side view illustration of the upper column shown
in Figure 8;
[0030] Figure 11 is a perspective illustration, from the front left side, of a
tunnel portion
of the frame assembly of the present invention;
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[0031 ] Figure 12 is another perspective illustration, from the rear left
side, of the tunnel
portion of the present invention shown in Figure 11;
[0032] Figure 13 is a perspective illustration, from the front left side,
showing the
combination of the frame assembly depicted in Figure 6 connected to the tunnel
portion depicted
in Figures 11 and 12;
[0033] Figure 14 is a perspective illustration, from the rear left side,
showing the
combination of the frame assembly depicted in Figure 6 connected to the tunnel
portion depicted
in Figures 11 and 12 and also showing a portion of a front suspension
assembly;
[0034] Figure 15 is a perspective illustration, from the front left side, of
some of the
components that are part of the front suspension assembly depicted in Figure
14;
[0035] Figure 16 is a perspective illustration, from the front left side, of a
portion of a
sub-frame that is part of the front suspension assembly illustrated in Figure
15;
[0036] Figure 17 is another perspective illustration, from the front left
side, of the front
suspension assembly for a snowmobile, constructed according to the teachings
of the present
invention, showing the positional relationship between the parts illustrated
in Figure 1 S and the
sub-frame illustrated in Figure 16;
[0037] Figure 18 is a side view schematic of the frame assembly of the present
invention
showing the positional relationship between the frame assembly and the engine,
among other
components;
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[0038] Figure 19 is a perspective illustration, from the left side, of the
frame assembly
according to the teachings of the present invention, also showing the
positional relationship
between the frame assembly, the engine, and the front suspension;
[0039] Figure 20 is another perspective illustration, from the front left
side, of the
combined frame assembly and tunnel portion constructed according to the
teachings of the
present invention, also showing the positional relationship between the frame
assembly, the
engine, and the front suspension;
[0040] Figure 21 is a front perspective illustration of the embodiment
depicted in Figure
20;
[0041] Figure 22 is a perspective illustration of a slightly different
embodiment from the
one depicted in Figure 20;
[0042] Figure 23 is a schematic side view illustration of the frame assembly
of the present
invention as embodied in a wheeled vehicle;
[0043] Figure 24 is a schematic side view illustration of the frame assembly
of the present
invention as embodied in a slightly modified version of a wheeled vehicle;
[0044] Figure 25 is an enlarged side view illustration of the frame assembly
of the present
invention as embodied in the wheeled vehicle shown in Figure 24;
[0045] Figure 26 is a perspective illustration, from the left rear, of the
frame assembly of
the present invention, showing some of the detail of the front suspension
incorporated into the
wheeled vehicle shown in Figures 23 and 24;
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[0046] Figure 27 is a perspective illustration, from the front left, showing
the frame
assembly of the present invention as depicted in Figure 26;
[0047] Figure 28 is a perspective illustration, from the rear left side of an
alternate
embodiment of the frame assembly of the present invention;
[0048] Figure 29 is a side view illustration of the frame assembly shown in
Figure 28;
[0049] Figure 30 is a top view of the frame assembly depicted in Figure 28;
[0050] Figure 31 is a side view illustration of the frame assembly shown in
Figure 29,
illustrating the variable positioning of the handlebars that is possible with
this embodiment of the
present invention;
[0051 ] Figure 32 is a perspective illustration of the embodiment shown in
Figure 31,
showing in greater detail the variations in positioning of the handlebars that
is made possible by
the construction of the present invention;
[0052] Figure 33 is a close-up side-view detail of the connection point
between the
handlebars and the frame assembly of the present invention, illustrating the
variable positioning
of the handlebars;
[0053] Figure 34 is a further illustration of the variable positioning feature
of the present
invention; and
[0054] Figure 35 is a graph showing the vertical displacement rate of the
frame of the
present invention in comparison with a prior art Bombardier snowmobile (the
ZXTM series) and a
prior art snowmobile made by Arctic Cat.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0055] Before delving into the specific details of the present invention, it
should be noted
that the conventions "left," "right," "front," and "rear" are defined
according to the normal,
forward travel direction of the vehicle being discussed. As a result, the
"left" side of a
snowmobile is the same as the left side of the rider seated in a forward-
facing position on the
vehicle (or travelling in a forward direction on the vehicle).
[0056] Figure 1 illustrates a rider operator 10 sitting on a prior art
snowmobile 12. Rider
is positioned on seat 14, with his weight distributed over endless track 16.
Motor 18 (shown
in general detail) is located over skis 20. As with any snowmobile, endless
track 16 is
operatively connected to motor (or engine) 18 to propel snowmobile 12 over the
snow. Motor or
engine 18 typically is a two-stroke internal combustion engine. Alternatively,
a 4-stroke internal
combustion engine may be substituted therefor. In addition, any suitable
engine may be
substituted therefor.
[0057] Figure 2 provides a side view of a snowmobile 22 constructed according
to the
teachings of the present invention. Here, rider/operator 24 is shown in a more
forward, motor
cross racing-like position, which is one of the aspects of the present
invention. In this position,
the weight of operator 24 is forward of the position of rider 10 in the prior
art example.
[0058] The positioning of rider 24 closer to motor 36 offers several
advantages that are
not achieved by the prior art. For example, since rider 24 is positioned
closer to the engine 36,
the center of gravity of rider 24 is closer to the center of gravity of the
vehicle, which is often at
the drive axle of the vehicle or near thereto. In other words, rider 24 has
his weight distributed
more evenly over the center of gravity of the vehicle. As a result, when the
vehicle traverses
CA 02350264 2001-06-12
rough terrain, rider 24 is better positioned so that he does not experience
the same impact from an
obstacle as rider 10 on snowmobile 12. The improved rider positioning
illustrated in Figure 2
also improves the rider's ability to handle the vehicle.
[0059] Figure 2 illustrates the basic elements of snowmobile 22. Snowmobile 22
includes
an endless track 26 at its rear for propulsion. A rear suspension 28 connects
endless track 26 to
the vehicle frame. Snowmobile 22 also includes a front suspension 30. Skis 32,
which are
operatively connected to handlebars 34, are suspended from the front
suspension 30 for steering
the vehicle. A motor or engine (preferably, an internal combustion engine) 36
is located at the
front of snowmobile 22, above skis 32. Operator 24 is seated on a seat 38,
which is positioned
above the endless track 26.
[0060] Three positional points of particular relevance to the present
invention are also
shown in Figure 2. Specifically, seat position 40, foot position 42, and hand
position 44 of
operator 24 are shown. In the modified seating position of operator 24, which
is made possible
by the teachings of the present invention, hand position 44 is forward of foot
position 42, which
is forward of seat position 40. The three positions define three angles, a, b,
and c between them
that help to define the seating position of operator 24, which permits rider
24 to be closer to
center of gravity 45 of the vehicle. Moreover, hand position 44 is forward of
center of gravity 45
of snowmobile 22.
[0061 ] Figure 3 provides an overlay between prior art snowmobile 12 and
snowmobile 22
constructed according to the teachings of the present invention. Rider 10 (of
prior art
snowmobile 12) is shown in solid lines while operator 24 (of snowmobile 22) is
shown in dotted
lines for comparison. The comparative body positions of rider 10 and operator
24 are shown. As
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CA 02350264 2001-06-12
is apparent, the present invention permits the construction of a snowmobile 22
where the rider 24
is in a more forward position. Moreover seat position 40, foot position 42,
and hand position 44
differ considerably from seat position 46, foot position 48, and hand position
50 in the prior art
snowmobile 12. In this position, the center of gravity of operator 24 is
closer to center of gravity
45 of snowmobile 22 than in the prior art example.
[0062] As a basis for comparison with the figures that provide the details of
the present
invention, Figure 4 provides an exploded view of a frame assembly 52 for a
snowmobile
constructed according to the teachings of the prior art. Frame assembly 52
includes, as its major
components, a tunnel 54 and an engine cradle 56. As illustrated, engine cradle
56 is positioned in
front of tunnel 54. Engine cradle 56 receives motor 18.
[0063] As shown in Figure 4, tunnel 54 is basically an inverted U-shaped
structure with a
top plate 58 integrally formed with left and right side plates 60, 62,
respectively. Top plate 58
provides the surface onto with seat 14 is mounted, as would be known to those
skilled in the art.
Foot boards 64 (of which only the left foot board is visible in Figure 4) are
integrally formed with
the side plates 60, 62 and extend outwardly, perpendicular to the plane of
side plates 60, 62. Foot
boards 64 provide a location on which rider 10 may place his feet during
operation of
snowmobile 12. While top plate 58, side plates 60, 62, and foot boards 64 are
preferably formed
from aluminum, any suitable alternative material may be used, as would be
recognized by those
skilled in the art. Moreover, while top plate 58, side plates 60, 62 and
footboards 64 are shown as
an integral structure, an integral construction is not required. Instead, top
plate 58, side plates 60,
62, and foot boards 64 may be separately manufactured and connected to one
another by any
suitable means known in the art.
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[0064] Figure 4 also shows that engine cradle 56 is connected to tunnel 54 by
any suitable
means known to those skilled in the art. For example, engine cradle 56 may be
welded or bolted
to tunnel 54. Engine cradle includes a bottom plate 66 and left and right side
walls 68, 70, which
are provided with left and right openings 72, 74, respectively. Left opening
72 is provided so that
the shafts for the transmission (typically a continuously variable
transmission or CVT) may
extend outwardly from left wall 68. The shafts that connect the engine 18 to
the transmission
pass through left opening 72. A gearbox (not shown) typically is provided on
the right side of
snowmobile 10. The shafts that connect engine 18 to the gearbox pass through
right opening 74.
Left and right openings 72, 74 also allow heat from engine 18 to be radiated
from engine cradle
56, which assists in cooling engine 18.
[0065] As Figure 4 illustrates, left side wall 68 is provided with a beam 76
that is
removably connected thereto. Beam 76 may be removed during servicing, for
example, to
facilitate access to the engine components and peripheral elements disposed
within left opening
72.
[0066] Figure 4 also illustrates the placement of a handlebar support element
78, which
connects to the rear of engine cradle 56. Handlebar support element 78 is
generally an inverted
U-shaped structure that extends upwardly from the combined engine cradle 56
and tunnel 54. A
bracket 80 is positioned at the midpoint of handlebar support element 78 and
provides structural
support for handlebars 82, which is used to steer snowmobile 12.
[0067] To provide an improved driver positioning, as described above, the
inventors of
the present invention appreciated the advantages of moving handlebars 82
forward of the position
shown in Figure 1. To do this, however, required a novel approach to the
construction of frame
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assembly 52 of snowmobile 12. The redesign resulted in the present invention,
which is
described in detail below.
[0068] As illustrated in Figure S, snowmobile 22 incorporates a completely
redesigned
frame assembly 84. Frame assembly 84 includes, among other elements, tunnel
86, engine cradle
88, and over-arching frame elements 90. As with snowmobile 12, snowmobile 22
includes a seat
94 on which rider 24 sits while operating snowmobile 22. Tunnel 86 is
connected to a rear
suspension 96 that contains a number of wheels 98 disposed on a slide frame
100 around which
an endless track 102 rotates to propel snowmobile 22 across the snow.
[0069] Endless track 102 is connected to engine 104 (preferably a two or four
stroke
internal combustion engine) positioned within engine cradle 88. Endless track
102 is connected
to engine 104 through a transmission 106, which is preferably a continuously
variable
transmission (or "CVT"), as is known in the art.
[0070] Two skis 108 are provided at the front of snowmobile 22 for steering.
Skis 108
are connected to engine cradle 88 through a front suspension 110. Front
suspension 110 connects
to skis 108 through a pivot joint 112 on the top of skis 108. Skis 108 are
operatively connected to
a steering shaft 114 that extends over engine 104. Steering shaft 114 is
connected, in turn, to
handlebars 116, which are used by operator 24 to steer snowmobile 22.
[0071] Figure 6 illustrates the individual elements of rear frame assembly 84
in greater
detail. Rear frame assembly 84 includes an upper column 118, which is an
inverted U-shaped
structural element. If necessary, upper column 118 may be reinforced with a
cross-member 120,
but this is not needed to practice the present invention. A left brace 122 and
a right brace 124 are
connected to a bracket 126 above upper column 118. A bushing or bearing (or
other similar
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CA 02350264 2001-06-12
element) 128 is attached to bracket 126 and accepts steering shaft 114
therethrough. It also
secures steering shaft 114 to rear frame assembly 84. Left and right braces
122, 124 include left
and right brackets 130, 132 at their lower portions. Left and right brackets
130, 132 secure left
and right braces 122, 124 to tunnel 86 of snowmobile 22.
[0072] It should be noted that, while the construction of frame assembly 84 is
illustrated
involves the use of tubular members, frame assembly 84 may also be constructed
according to a
monocoque or pseudo-monocoque technique. A monocoque construction is one where
a single
sheet of material is attached to an underlying frame (such as with the
construction of an aircraft).
The skin applied to the frame adds rigidity to the underlying frame structure.
In a similar
manner, a pseudo-monocoque technique provides a rigid structure by providing a
frame
constructed from a single sheet of material.
[0073] Instead of constructing frame assembly 84 from a number of tubular
members,
frame assembly 84 may be constructed from a single sheet of material (such as
aluminum) that
has been pressed or molded into the appropriate shape using a pseudo-monocoque
manufacturing
technique. As would be understood by those skilled in the art, this would
result in a construction
that has a high strength with a low weight.
[0074] Figure 7 illustrates a forward support assembly 134 (also called front
triangle
134), which connects to bracket 126 and extends forwardly of bracket 126.
Forward support
assembly 134 includes a bracket 136 at its rear end that connects to bracket
126 of frame
assembly 84 (preferably bolted). Forward support assembly 134 also has left
and right braces
138, 140 that extend forwardly and downwardly from bracket 136 and are
connected thereto
preferably by welding. Left and right braces 138, 140 are connected at their
forward ends by a
CA 02350264 2001-06-12
cross-member 142, which includes a plurality of holes 144 therein to lighten
the weight thereof.
Left and right connecting brackets 145, 146 are connected to cross-member 142.
The left and
right connecting brackets 145, 146 connect, in turn, to front suspension 110.
[0075] Figure 8, 9, and 10 illustrate upper column 118 in greater detail. As
described
above, upper column 118 is essentially an inverted U-shaped member that is
preferably tubular in
shape to facilitate its construction. Upper column 118 preferably is bent into
the appropriate
shape from a straight tube with the dimensions shown. As would be understood
by those skilled
in the art, however, upper column 118 need not be made as a tubular member.
[0076] Upper column 118 has left and right legs 148, 150 that extend
downwardly from
an apex 152. A bracket 154 is disposed at apex 152 for connection to bracket
126 of frame
assembly 84. Preferably, bracket 154 is welded at the apex of upper column 118
(however any
other suitable attachment means is possible). Left leg 148 includes a bracket
156 at its lower-
most portion that connects left leg 148 to engine cradle 88. Similarly, right
leg 1 SO includes a
bracket 158 at its lower-most portion to connect right leg 150 to engine
cradle 88. Preferably,
brackets 156, 158 are welded to upper column 118. Left and right legs 148, 150
preferably attach
to engine cradle 88 via bolts or other suitable fasteners.
[0077] Figures 11 and 12 illustrate tunnel 86 in greater detail. Tunnel 86
includes a top
plate 160 with left and right downwardly extending side plates 162, 164. A
left foot rest 166
extends outwardly from the bottom of left side plate 162. Similarly, a right
foot rest 168 extends
outwardly from the bottom portion of right side plate 164. Left and right foot
rests 166, 168
provide a location along tunnel 86 onto which rider 24 may place his or her
feet while operating
snowmobile 22.
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[0078] Left side plate 162 extends forwardly beyond the front portion 170 of
tunnel 86 to
form a left engine cradle wall 172. Similarly, right side plate 164 extends
forwardly of front end
170 of tunnel 86 to form right engine cradle wall 174. At the lower edge of
left and right engine
cradle walls 172, 174, there are laterally extending portions 176, 178, which
serve to strengthen
left and right engine cradle walls 172, 174. Removable elements 180 extend
between left foot
rest 166 and left laterally extending portion 176. Removable portions 180 may
or may not be
removed between left foot rest 166 and left laterally extending portion 176.
Figure 11 shows
removable portions 180 removed, while Figure 12 shows removable portions 180
not removed.
It should be noted that the same removable portions 180 may or may not extend
between right
foot rest 168 and right laterally extending portion 178.
[0079] Left engine cradle wall 172 preferably includes an opening 182
therethrough.
Opening 182 permits the shafts from transmission 106 to pass therethrough.
Unlike left engine
cradle wall 172, right engine cradle wall 174 does not include such an
opening. Instead, right
engine cradle wall 174 is essentially solid. Due to its construction, right
engine cradle wall 174
reflects radiant heat from engine 104 back to engine 104 to assist in
minimizing heat dissipation
from engine 104. Left and right openings 184, 186 are provided through left
and right engine
cradle walls 172, 174 so that a drive shaft 188 may pass therethrough. Drive
shaft 186 connects
to endless track 102 for propulsion of snowmobile 22. Opening 182 may include
a member 189
about its periphery, also as illustrated in Figures 11 and 12, that provides
clearance for the engine.
Left engine cradle wall 172 also includes an opening 192 above opening 184
through which a
shaft passes for part of transmission 106.
[0080] Figures 13 and 14 illustrate a combination of a variation of frame
assembly 190
connected to tunnel 86. Frame assembly 190 includes upper column 118 as
illustrated in Figures
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8-10. However, frame assembly 190 differs somewhat from frame assembly 84. For
example,
left and right braces 194, 196 are shaped so that they extend outwardly from
the positions defined
by left and right braces 122, 124. As illustrated, left and right braces 194,
196 include elbows
198, 200. A cross-brace 202 optionally may be placed between left and right
braces 194, 196 to
add structural rigidity to frame assembly 190. As with frame assembly 84, a
bracket 126 is
provided at apex 204 where left and right braces 194, 196 meet one another.
Forward support
assembly 134 is the same as depicted in Figure 7. A front engine cradle wall
206 is also shown in
Figure 13.
[0081] Figures 15-17 illustrate various aspects of front suspension 110 and
associated
structures. While the figures illustrate the embodiment preferably used in
combination with
snowmobile 22, it should be recognized that front suspension 110 may also be
used in
combination with a wheeled vehicle, as will be discussed in connection with
Figures 23-27.
[0082] Front suspension 110 includes left and right ski legs 208, 210. Left
and right ski
legs 208, 210 are preferably made from aluminum and are preferably formed as
extrusions.
While an aluminum extrusion is preferred for left and right ski legs 208, 210,
those skilled in the
art would appreciate that ski legs could be made from any suitable material
and in any acceptable
manner that would provide similar strength and low weight characteristics.
Left and right ski
legs 208, 210 include holes 212, 214 through which a fastener (not shown) is
disposed to
pivotally connect skis 32 to snowmobile 22, as shown in Figure 2.
[0083] Left and right ski legs 208, 210 are movably connected to left and
right support
arms 216, 218. Left and right suspension arms 216, 218 include lower left and
right suspension
support arms 220, 222 and upper left and right suspension support anus 224,
226.
18
CA 02350264 2001-06-12
[0084] As shown in Figures 15 and 17, lower left suspension support arm 220
connects to
left ski leg at lower left attachment point 228 preferably through a ball
joint (not shown) so that
left ski leg 208 may pivot and rotate with respect to lower left suspension
support arm 220.
Similarly, lower right suspension support arm 222 connects to right ski leg
210 at lower right
attachment point 230, preferably through a ball joint. Upper left suspension
support arm 224
preferably attaches to left ski leg 208 at upper left attachment point 232,
preferably through a ball
joint or other suitable means. In addition, upper right suspension support arm
226 connects to
right ski leg 210 at upper right attachment point 234 through a ball joint or
other suitable means.
[0085] Lower left suspension support arm 220 includes front and rear members
236, 238,
which meet at apex 240 where they connect with left lower eyelet 242. Front
member 236
includes a joint 244 at an inner end, and rear member 238 includes a joint 246
also at an inner
end. Similarly, lower right suspension support arm 222 includes front and rear
members 248,
250, which meet at apex 252 where they connect with right lower eyelet 254.
Front member 248
includes a joint 256 at an inner end and rear member 250 includes a joint 258
also at an inner end.
[0086] Upper left suspension support arm 224 includes front and rear members
260, 262,
which meet at apex 264 where they connect with upper left eyelet 266. Front
member 260
includes a joint 268 at an inner end, and rear member 262 includes a joint 270
also at an inner
end. Similarly, upper right suspension support arm 226 includes front and rear
members 272,
274, which meet at apex 276 where they connect with upper right eyelet 278.
Front member 272
includes a joint 280 at an inner end and rear member 274 includes a joint 282
also at an inner end.
[0087] At a point inward from apex 240, lower left suspension support arm 220
includes a
left bracket 284 that is connected to and extends partially along front and
rear members 236, 238.
19
CA 02350264 2001-06-12
Similarly, lower right suspension support arm 222 includes a right bracket 286
that is connected
to and extends partially along front and rear members 248, 250. Slidably
attached to rear
member 238 of lower left suspension arm 220 is a left pivot block 288. A right
pivot block 290 is
slidably attached to rear member 250 of lower right suspension support arm
222. A stabilizer bar
292 is connected between left and right pivot blocks 288, 290. Stabilizer bar
292 is adapted to
slide and pivot by way of left and right pivot blocks 288, 290. These blocks
288, 290 slide
relative to left and right lower suspension support arms 220, 222. Left and
right bushings 296,
298 are provided to allow some rotation of the components of front suspension
110. Left and
right ski legs 208, 210 rotatably connect to front suspension 110 for
facilitating movement of skis
32.
[0088] Figure 16 illustrates sub-frame 294, which is essentially a unitary, V-
shaped
structure. Sub-frame 294, which forms a part of front suspension 110, includes
a central channel
300 flanked on either side by left and right upwardly extending panels 302,
304. Left upwardly
extending panel 302 includes a left lower panel 306 connected to left
transition structure 308 and
left triangular panel 310. Similarly, right upwardly extending panel 304
includes a right lower
panel 312 connected to right transition structure 314 and right triangular
panel 316. While sub-
frame 294 preferably is a unitary structure (an integrally-formed structure),
sub-frame 294 need
not be constructed in this manner. As would be understood by those skilled in
the art, sub-frame
294 may be assembled from a number of separate elements that are connected
together by any
suitable means such as by welding or by fasteners.
[0089] As illustrated in Figure 17, sub-frame 294 is an integral part of front
suspension
110 and connects to left support arm 216 and right support arm 218 through a
number of brackets
318 connected at various locations on sub-frame 294.
CA 02350264 2001-06-12
[0090] Figure 18 is a side view of one embodiment of the completed frame
assembly 84
of the present invention. As shown, over-arching frame elements 90 are
connected between
tunnel 86 and sub-frame 294 to establish an apex 320 to which steering shaft
114 is connected.
[0091 ] Figure 19 is a perspective illustration of the embodiment of the
present invention
shown in Figures 13 and 14 to assist in understanding the scope and content of
the present
invention. As illustrated, drive shaft 322 extends through left opening 182 in
left engine cradle
wall 172. A portion of gearbox 324 is also visible. In addition, left shock
absorber 326, which is
connected between cross-member 142 and left support arm 216, is illustrated.
Right shock
absorber, which extends between cross-member 142 and right support arm 218 is
visible in
Figure 20. Furthermore, left forward foot wall 330 is shown at the forward end
of left foot rest
166. A similar forward foot wall may be provided on the right side of
snowmobile 22 (but is not
illustrated herein).
[0092] Figures 20 and 21 illustrate further details of the present invention
by showing the
various elements from slightly different perspective views. Figure 22
illustrates the modified
version of the elements of the present invention shown in Figures 6 and 7.
Here, left and right
braces 122, 124 are illustrated instead of left and right braces 194, 196. As
discussed previously,
left and right braces 122, 124 differ from left and right braces 194, 196 in
that they are not bent
but, instead, are straight elements of overarching frame 90. The same left and
right braces 122,
124 are shown in Figure 18. As would be understood by those skilled in the
art, the two different
embodiments of these braces are interchangeable. In addition, their shape may
be altered
depending on the requirements of the particular vehicle design, as would be
understood by those
skilled in the art.
21
CA 02350264 2001-06-12
[0093] Left and right braces 194, 196 are bent to accommodate an airbox (not
shown)
between them. Left and right braces 122, 124 are not bent because they do not
need to
accommodate an airbox.
[0094] Figure 20 also illustrates steering gear box 115 at the bottom end of
steering shaft
114 that translates the movement of handlebars 116 into a steering motion of
skis 32.
(0095] Figures 23-27 illustrate alternate embodiments of the present invention
that are
designed for a wheeled vehicle 332, rather than a snowmobile 22. For the most
part, the elements
designed for wheeled vehicle 332 are the same as those for snowmobile 22,
except for those
elements required to attach wheels 334 to wheeled vehicle 332.
[0096] In the preferred embodiment of wheeled vehicle 332, the vehicle
includes two
front wheels 334 and a single rear wheel 336. As would be understood by those
skilled in the art,
however, wheeled vehicle 332 may be constructed with two rear wheels rather
than one. If so,
wheeled vehicle 332 would be a four-wheeled vehicle rather than the three-
wheeled vehicle
shown.
[0097] Wheeled vehicle 332 includes a seat 338 disposed over tunnel 86 in the
same
manner as snowmobile 22. The vehicle includes engine 104 at its forward end,
encased by
fairings 340. Fairings 340 protect engine 104 and provide wheeled vehicle 332
with an
aesthetically pleasing appearance. Engine 104 is connected to CVT 106, which
translates the
power from engine 104 into motive power for wheeled vehicle 332.
[0098] As shown in Figure 23, CVT 106 is connected by suitable means to drive
shaft
342, which is connected to rear wheel 336 by a drive chain 344. A sprocket 346
is connected to
22
CA 02350264 2001-06-12
drive shaft 342. A similar sprocket 348 is provided on the shaft connected to
rear wheel 336.
Drive chain 344 is an endless chain that connects sprockets 346, 348 to one
another. To stop
wheeled vehicle 332 during operation, disc brakes 350 are connected to front
wheels 334. Disc
brakes 350 clamp onto discs 352 to slow or stop wheeled vehicle 332 in a
manner known to those
skilled in the art.
[0099] A rear suspension 354 is provided under tunnel 86. Rear suspension 354
absorbs
shocks associated with the terrain over which wheeled vehicle 332 travels.
Rear suspension 354
replaces rear suspension 28 on snowmobile 22.
[00100] Figure 24 illustrates an alternate embodiment of wheeled vehicle 356.
Wheeled
vehicle 356 differs in its construction at the rear. Specifically, rear end
358 is shorter than that
shown for wheeled vehicle 332. In addition, wheeled vehicle 356 includes a
four stroke engine,
rather than the two stroke engine 104 illustrated for wheeled vehicle 332.
Also, wheeled vehicle
356 includes a manual speed transmission 360 (with a clutch) rather than
continuously variable
transmission 106, as illustrated with other embodiments of the present
invention. Both
constructions of the wheeled vehicle, as well as many other variations, are
contemplated within
the scope of the present invention. In addition, as discussed above, the
present invention may be
used with a two or four stroke engine (or any other type of engine that
provides the motive power
for the vehicle).
[00101 ] Figure 25 illustrates in greater detail the embodiment of the present
invention
shown in Figure 24.
[00102] Figures 26-27 illustrate the basic frame assembly contemplated for
wheeled
vehicles 332, 356. For either vehicle, the construction of frame assembly 191
is similar to that
23
CA 02350264 2001-06-12
previously described. This embodiment differs in that left and right wheel
knuckles 366, 368 are
provided so that wheels 334 may be attached thereto. In most other respects,
the construction of
frame assembly 191 is the same as that previously described.
[00103] The variable geometry of steering shaft 364 will now be described in
connection
with Figures 28-34.
[00104] As illustrated in Figure 28, left brace 122 and right brace 124 extend
upwardly
from tunnel 370 to apex 372 where they connect to variable geometry steering
bracket 374.
Upper column 118 extends from left engine cradle wall 376 and right engine
cradle wall 174 and
also connects to variable geometry steering bracket 374. Forward support
assembly 134 extends
from sub-frame 294 to variable geometry steering bracket 374.
[00105] Variable geometry steering bracket 374 is essentially a U-shaped
element with a
rear end 376 and a forward end 378. At rear end 376, a first cross-member 380
extends between
left and right legs 382, 384 of variable geometry steering bracket 374 to
define a closed structure.
A second cross member 386 extends between left and right legs 382, 384 forward
of first cross
member 380 and defines a U-shaped opening 387 toward forward end 378 of
variable geometry
steering bracket 374. A first pair of holes 388 and a second pair of holes 390
are disposed
through left and right legs 382, 382 of variable geometry steering bracket 374
and provide
separate attachment points for steering shaft 364. Figure 29 illustrates the
same structures in side
view and Figure 30 illustrates the same structures in top view.
[00106] This embodiment of the frame assembly of the present invention differs
from the
previous embodiments in a few respects. First, left engine cradle wall 393
includes a C-shaped
opening 392 instead of opening 182. C-shaped opening 392 facilitates
maintenance of an engine
24
CA 02350264 2001-06-12
(not shown) in engine cradle 394. Second, an elongated radiator 396 is
integrated into tunnel
370. Radiator 396 includes an inlet 398 and an outlet 400 that are connected
to the cooling
system of the engine to assist in reducing the temperature of the coolant
therein. To facilitate
dissipation of heat, radiator 396 includes fms 402 on its underside.
[00107] Figure 31 provides another side view of the frame assembly of the
present
invention and illustrates the two positions of steering shaft 364 made
possible by the construction
of variable geometry steering bracket 374. To accommodate the variable
geometry of steering
shaft 362 and handlebars 116, steering shaft 364 includes a bend 402 at its
lower end. Steering
shaft 364 passes through a bearing or bushing (not shown) at its upper end
that is connected to
variable geometry steering bracket 374 at either of first or second pairs of
holes 388, 390. By
selecting either first or second pairs of holes 388, 390, first and second
handlebar positions 404,
406 are selectable. As would be recognized by those skilled in the art,
however, variable
geometry steering bracket 374 may be provided with greater that two pairs of
holes 388, 390 to
further increase the variability handlebars 116. Also, variable geometry
steering bracket 374 may
be provided with a construction that permits infinite variation of the
position of handlebars, as
would be understood by those skilled in the art, should such a construction be
desired.
[00108] Figures 32-34 provide additional views of the variable positioning of
the
handlebars 116 to facilitate an understanding of the scope of the present
invention.
[00109] Frame assembly 84, 190, 191 of the present invention uniquely
distributes the
weight loaded onto the vehicle, whether it is snowmobile 22 or one of wheeled
vehicles 332, 356.
Each of the main components of the frame assembly 84, 190, 191 forms a
triangular or pyramidal
configuration. All of the bars of the frame assembly 84, 190, 191 work only in
tension and
CA 02350264 2001-06-12
compression, without bending. Therefore, each bar of frame assembly 84, 190,
191 intersects at
a common point, the bracket 126 (in the non-variable steering geometry) or
variable geometry
steering bracket 374. With this pyramidal shape, the present invention creates
a very stable
geometry.
[00110] Specifically, the structure of frame assembly 84, 190, 191 enhances
the torsional
and structural rigidity of the frame of the vehicle. This improves handling.
Usually, with a
snowmobile, there is only a small torsional moment because the width of the
snowmobile is only
about 15 inches. An ATV, on the other hand, has a width of about 50 inches
and, as a result,
experiences a significant torsional moment. Therefore, to construct a frame
assembly that is
useable in either a snowmobile or an ATV, the frame must be able to withstand
the torsional
forces associated with an ATV.
[00111 ] Not only does frame assembly 84, 190, 191 reduce torsional bending,
it also
reduces the bending moment from front to rear. The increased rigidity in both
directions further
improves handling.
[00112] In addition, the creation of frame assembly 84, 190, 191 has at least
one further
advantage in that the frame can be made lighter and stronger than prior art
frame assemblies
(such as frame assembly 52, which is illustrated in Figure 4). In the
conventional snowmobile,
frame assembly 52 included a tunnel 54 and an engine cradle 56 that were
riveted together.
Because frame assembly 84, 190, 191 adds strength and rigidity to the overall
construction and
absorbs and redistributes many of the forces encountered by the frame of the
vehicle, the panels
that make up the tunnel 86 and the engine cradle 88 need not be as strong or
as thick as was
required for the construction of frame assembly 52.
26
CA 02350264 2001-06-12
[00113] In the front of the vehicle, left and right shock absorbers 326, 328
are connected to
forward support assembly 134 so that the forces experienced by left and right
shock absorbers
326, 328 are transmitted to frame assembly 84, 190, 191. In the rear of the
vehicle, the left and
right braces 122, 124 are orientated with respect to the rear suspension.
Upper column 118 is
positioned close to the center of gravity of the vehicle's sprung weight. The
sprung weight
equals all of the weight loaded onto the vehicle's entire suspension. The
positioning of these
elements such that they transmit forces encountered at the front, middle and
rear of the vehicle to
an apex creates a very stable vehicle that is capable of withstanding
virtually any forces that the
vehicle may encounter during operation without sacrificing vehicle
performance.
[00114] Figure 35 illustrates the degree to which the rigidity of a frame
constructed
according to the teachings of the present invention is improved. The highest
line on the graph
shows that for a 100 kg load, the vertical displacement of the frame of the
present invention is
only -2 mm. However, in the prior art Bombardier ZXTM model snowmobile, a load
of only SO
kg produced a vertical displacement of -6 mm. In addition, a load of about 30
kg on the frame
for the prior art Arctic Cat~ snowmobile produced a vertical displacement of -
6 mm. In other
words, the structural rigidity of the frame assembly of the present invention
is greatly improved.
[00115] While the invention has been described by way of example embodiments,
it is
understood that the words which have been used herein are words of
description, rather than
words of limitation. Changes may be made, within the purview of the appended
claims without
departing from the scope and the spirit of the invention in its broader
aspects. Although the
invention has been described herein with reference to particular structures,
materials, and
embodiments, it is understood that the invention is not limited to the
particulars disclosed.
27
