Note: Descriptions are shown in the official language in which they were submitted.
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ENGINE CRADLE FOR A VEHICLE
1. Field of the Invention
The present invention concerns generally concerns the construction of vehicles
such as
snowmobiles, all terrain vehicles ("ATVs"), and other similar vehicles. More
specifically, the
present invention concerns the construction of an engine cradle for such
vehicles.
2. Description of Related Art and General Background
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 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.
As a general rule, the prior art includes few, if any, examples of a common
design
approach to ATVs and snowmobiles. Primarily, this appears to be due to the
fact that these
vehicles were designed traditionally from two radically different starting
points.
Snowmobile frames traditionally have been constructed with a tunnel and an
engine
cradle, which are individual elements made from metal, plate-like elements, as
shown in Fig. 4.
ATV frames, on the other hand, have been constructed in much the same way as
motorcycle
frames by connecting a number of tubular frame elements to one another.
In the case of snowmobiles, the tunnel and engine cradle combination (referred
to herein
as the "frame" or "frame assembly") traditionally has been made of a very
strong but light-weight
material such as aluminum. To withstand the forces encountered under normal
operating
CA 02350285 2001-06-12
conditions, the individual plate elements of the tunnel and engine cradle have
been relatively
thick so that they do not bend or buckle under high loads. Unfortunately, this
adds significantly
to the overall weight of the vehicle.
Moreover, several holes need to be provided at various locations in the engine
cradle to
accommodate shafts for the drive axle, the transmission, and the gearbox.
Traditionally, the
holes have been drilled into the engine cradle after its construction. A
problem with this
construction technique is that the holes may not line up as precisely as the
manufacturer would
like. In some cases, the manufacturer must expend considerable resources to
align these shaft
holes before producing the final vehicle product.
SUMMARY OF THE INVENTION
In view of the foregoing, one object of the present invention is to exploit
the design
elements of a snowmobile that are easily and readily transferred to the design
of an ATV based
on the same basic frame structure.
To that end, one object of the present invention is to provide an engine
cradle adapted for
receiving an engine that includes a left side wall defining a C-shaped opening
therein. The
engine cradle also includes a right side wall that is essentially solid and
that provides a reflective
surface for reflecting heat to the engine when contained within the engine
cradle. As would be
known by one skilled in the art, the right side wall could define the C-shaped
opening and the left
side wall could define the wall that is essentially solid. The engine cradle
also includes a front
wall that is connected between forward portions of the left and right side
walls. Finally, the
engine cradle has a bottom panel and apron connected between bottom portions
of the front, left
side, and right side walls.
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It is another object of the present invention to provide front, left side, and
right side walls
that are stamped from a sheet of metal. The holes in the walls are stamped
into the metal in the
same plane that the walls are stamped from the metal sheet. This assured that
the holes align with
one another during manufacture of the frame assembly.
One further object of the present invention is to provide an engine cradle
where the walls
have a thickness of less than about 2.5 mm and, more preferably, about 2.0 mm.
Still another object of the present invention is to provide a vehicle frame
with a left side
structure and a right side structure. A radiator connects the left side
structure and the right side
structures to one another at a rear portion. A front wall connects between
front portions of the
left and right side structures. An engine cradle bottom plate and apron
connects to the front wall
and forward portions of the left and right side structures to define a cradle
adapted to receive an
engine. The left side structure, the right side structure, the front wall, and
the engine cradle
bottom plate are each stamped from a sheet of metal.
It is a further object of the present invention to provide a foot-gripping
element on a
footrest that includes a jagged portion extending upwardly from the footrest
and defining teeth at
a top portion thereof. A deflector portion is positioned at an opposite side
of a hole through the
footrest and is angled downwardly from the footrest to discourage particles
from being stirred up
and passing through the hole onto a top portion of the footrest.
It is still another object of the present invention to incorporate a heat
exchanger into the
tunnel. In an alternate embodiment, the heat exchanger is a radiator that
extends substantially the
length of the tunnel and assists in dissipating heat from engine coolant
circulating therethrough.
Still other objects of the present invention will be made apparent by the
discussion that
follows.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully described in conjunction with the following
drawings, in
which like reference characters denote like features, wherein:
Fig. 1 is a side-view schematic illustration of a prior art snowmobile,
showing the prior art
positioning of a rider thereon;
Fig. 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;
Fig. 3 is an overlay comparison between the a prior art snowmobile (of the
type depicted
in Fig. 1) and a snowmobile constructed according to the teachings of the
present invention (as
shown in Fig. 2), illustrating the difference in passenger positioning, among
other features;
Fig. 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);
Fig. 5 is a side view schematic illustration of the snowmobile illustrated in
Fig. 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;
Fig. 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;
Fig. 7 is a perspective illustration of a forward support frame, which
connects with the
portion of the frame assembly depicted in Fig. 6;
Fig. 8 is a front view illustration of an upper column of the frame assembly
shown in Fig.
6;
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Fig. 9 is a left side view illustration of the upper column depicted in Fig.
8;
Fig. 10 is a right side view illustration of the upper column shown in Fig. 8;
Fig. 11 is a perspective illustration, from the front left side, of a tunnel
portion of the
frame assembly of the present invention;
Fig. 12 is another perspective illustration, from the rear left side, of the
tunnel portion of
the present invention shown in Fig. 11;
Fig. 13 is a perspective illustration, from the front left side, showing the
combination of
the frame assembly depicted in Fig. 6 connected to the tunnel portion depicted
in Figs. 11 and 12;
Fig. 14 is a perspective illustration, from the rear left side, showing the
combination of the
frame assembly depicted in Fig. 6 connected to the tunnel portion depicted in
Figs. 11 and 12 and
also showing a portion of a front suspension assembly;
Fig. 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 Fig. 14;
Fig. 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 Fig. 15;
Fig. 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 Fig. 15
and the sub-frame
illustrated in Fig. 16;
Fig. 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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Fig. 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;
Fig. 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;
Fig. 21 is a front perspective illustration of the embodiment depicted in Fig.
20;
Fig. 22 is a perspective illustration of a slightly different embodiment from
the one
depicted in Fig. 20;
Fig. 23 is a schematic side view illustration of the frame assembly of the
present invention
as embodied in a wheeled vehicle;
Fig. 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;
Fig. 25 is an enlarged side view illustration of the frame assembly of the
present invention
as embodied in the wheeled vehicle shown in Fig. 24;
Fig. 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 Figs. 23 and 24;
Fig. 27 is a perspective illustration, from the front left, showing the frame
assembly of the
present invention as depicted in Fig. 26;
Fig. 28 is a perspective illustration, from the rear left side of an alternate
embodiment of
the frame assembly of the present invention;
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Fig. 29 is a side view illustration of the frame assembly shown in Fig. 28;
Fig. 30 is a top view of the frame assembly depicted in Fig. 28;
Fig. 31 is a side view illustration of the frame assembly shown in Fig. 29,
illustrating the
variable positioning of the handlebars that is possible with this embodiment
of the present
W venhon;
Fig. 32 is a perspective illustration of the embodiment shown in Fig. 31,
showing in
greater detail the variations in positioning of the handlebars that is made
possible by the
construction of the present invention;
Fig. 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;
Fig. 34 is a further illustration of the variable positioning feature of the
present invention;
Fig. 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;
Fig. 36 is a cross-sectional illustration of the construction of the tunnel of
the present
invention, showing the positioning of a gas tank thereon;
Fig. 36(a) is an enlarged version of the radiator of Fig. 36 schematically
illustrating the
connection of the radiator to the left and right side structures;
Fig. 37 is an enlarged, perspective illustration of a foot-gripping element
constructed
according to the teachings of the present invention; and
Fig. 38 is a cross-sectional illustration, taken along line 38-38 in Fig. 37,
of the foot-
gripping element constructed according to the teachings of the present
invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before delving into the specific details of the present invention, it should
be noted that the
conventions "left," "right," "front," "forward", "upward", "downward" 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).
Fig. 1 illustrates a rider operator 10 sitting on a prior art snowmobile 12.
Rider 10 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.
Fig. 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,
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.
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 rough
terrain, rider 24 is better positioned so that he does not experience the same
impact from an
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CA 02350285 2001-06-12
obstacle as rider 10 on snowmobile 12. The improved rider positioning
illustrated in Fig. 2 also
improves the rider's ability to handle the vehicle.
Fig. 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.
Three positional points of particular relevance to the present invention are
also shown in
Fig. 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
the center of gravity 45
of the vehicle. Moreover, hand position 44 is forward of center of gravity 45
of snowmobile 22.
Fig. 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
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
SO in the prior art
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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.
As a basis for comparison with the figures that provide the details of the
present
invention, Fig. 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.
As shown in Fig. 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 Fig. 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.
Fig. 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
CA 02350285 2001-06-12
the shafts for the transmission (typically a continuously variable
transmission or CVT) may
extend outwardly from left wall 68. The shafts that connect the 18 to the
transmission pass
through left opening 72. A gearbox (not shown) typically is provided on the
right side of
snowmobile 10. 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.
As Fig. 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.
Fig. 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.
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 Fig. 1. To do this, however, required a novel approach to the
construction of frame
assembly 52 of snowmobile 12. The redesign resulted in the present invention,
which is
described in detail below.
As illustrated in Fig. 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
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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.
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.
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.
Fig. 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. The upper column 118 is reinforced with a cross-member 120. 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 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.
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).
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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.
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.
Fig. 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 by welding). 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 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. Left and right
connecting
brackets 145, 146 connect, in turn, to front suspension 110.
Figs. 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.
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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 150 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.
Figs. 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 footrest
166 extends
outwardly from the bottom of left side plate 162. Similarly, a right footrest
168 extends
outwardly from the bottom portion of right side plate 164. Left and right
footrests 166, 168
provide a location along tunnel 86 onto which rider 24 may place his or her
feet while operating
snowmobile 22.
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. Fig. 11
shows removable
portions 180 removed, while Fig. 12 shows removable portions 180 not removed.
It should be
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noted that the same removable portions 180 may or may not extend between right
foot rest 168
and right laterally extending portion 178.
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 Figs. 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.
Figs. 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
Figs. 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 Fig. 7. A front engine cradle wall 206 is also
shown in Fig. 13.
CA 02350285 2001-06-12
Figs. 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 Figs. 23-27.
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 Fig. 2.
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 arms 224, 226.
As shown in Figs. 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.
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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, that
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.
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.
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.
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
17
CA 02350285 2001-06-12
right ski legs 208, 210 rotatably connect to front suspension 110 for
facilitating movement of skis
32.
Fig. 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.
As illustrated in Fig. 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.
Fig. 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.
Fig. 19 is a perspective illustration of the embodiment of the present
invention shown in
Figs. 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
18
CA 02350285 2001-06-12
extends between cross-member 142 and right support arm 218 is visible in Fig.
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).
Figs. 20 and 21 illustrate further details of the present invention by showing
the various
elements from slightly different perspective views. Fig. 22 illustrates the
modified version of the
elements of the present invention shown in Figs. 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
Fig. 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.
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.
Fig. 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.
Figs. 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.
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,
19
CA 02350285 2001-06-12
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.
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.
As shown in Fig. 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 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.
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.
Fig. 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
CA 02350285 2001-06-12
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).
Fig. 25 illustrates in greater detail the embodiment of the present invention
shown in Fig.
24.
Figs. 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 previously
described. This embodiment differs in that left and right wheel knuckles 366,
368 are provided
so wheels 334 may be attached thereto. In most other respects, the
construction of frame
assembly 191 is the same as that previously described.
The variable geometry of steering shaft 364 will now be described in
connection with
Figs. 28-34.
As illustrated in Fig. 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.
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
21
CA 02350285 2001-06-12
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. Fig. 29 illustrates the
same structures in side
view and Fig. 30 illustrates the same structures in top view.
Fig. 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.
Figs. 32-34 provide additional views of the variable positioning of the
handlebars 116 to
facilitate an understanding of the scope of the present invention.
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
compression, without bending. Therefore, each bar of frame assembly 84, 190,
191 intersects at
22
CA 02350285 2001-06-12
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.
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.
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.
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 Fig. 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.
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
23
CA 02350285 2001-06-12
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.
Fig. 35 illustrates the degree to which the rigidity of a frame constructed
according to the
teachings of the present invention is improved. The test illustrated here is
known as a three-point
test because three points on the frame are held in a fixed position and a
fourth point is subjected
to a measurable force. The displacement of the frame under a particular load
is measured. The
smaller the distance that the frame moves under a given stress, the greater is
the rigidity of that
frame.
Here, the highest line on the graph illustrates 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 50 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.
Other aspects of the present invention will now be described in connection
with Figs. 27-
38.
In each of the embodiments illustrated throughout the Figs., left leg 148 of
upper column
118 attaches to the interior surface of right engine cradle wall 174. Right
leg 150 of upper
24
CA 02350285 2001-06-12
column 118 attaches to the exterior surface of left engine cradle wall 393. In
this arrangement,
upper column 118 may be detached from engine cradle 394 and removed easily by
sliding upper
column 118 from engine cradle 394 through C-shaped opening 392.
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 (not
shown) in engine cradle 394, because it facilitates access to the engine from
the left side, which is
the side to which the engine sits within 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 fins 402 on
its underside.
Tunnel 370 and engine cradle 394 are constructed so that they form an integral
unit, once
assembled. The combined tunnel 370 and engine cradle 394 are essentially made
up of three
parts, a left side structure 408, a right side structure 410, and radiator
396. Left side structure 408
is the combination of left engine cradle wall 393 and left side plate 162.
Right side structure is
the combination of right engine cradle wall 174 and right side plate 164. In
addition, front wall
206 and engine cradle bottom 207 also form a part of the combined structure
made by tunnel 370
and engine cradle 394.
Left side structure 408 and right side structure 410 are stamped from a single
sheet of
metal. The rear portion of left side structure 408 is then bent at right
angles to left side plate 162
to form a left top portion 412 of tunnel 370. Similarly, the rear portion of
right side structure 410
is bent at right angles to right side plate 164 also to form a right top
portion 414 of tunnel 370.
CA 02350285 2001-06-12
Radiator 396 extends between left top portion 412 and right top portion 414
and connects left
side structure 408 to right side structure 410.
Cradle wall 393 include bolt holes 395 where bolts (not shown) connect to an
engine
mount 323, shown in Fig. 19, in order to connect the engine 104 to the cradle
wall 393. To
facilitate assembly of the engine 104 with the vehicle, the engine mount 323,
which is attached to
the cradle wall 393 with bolts (not shown) which pass through the cradle wall
393, unlike through
the bottom plate 66 in the prior art engine cradle shown in Fig. 4.
The attachment between the radiator 396 and the left and right side structures
408 and 410
is shown in Fig. 36(a). The radiator 396 includes upper lips 397 and lower
lips 399 that define C-
shaped side portions of the radiator 396 that hold portions of the left and
right side structures 408
and 410.
In addition, because radiator 396 connects left side structure 408 with right
side structure
410 in the manner shown, additional space is created on tunnel 370 for a
larger fuel tank 416
(shown in dotted lines in Fig. 18). As illustrated in Fig. 36, fuel tank 416
has an inverted U-
shaped appearance so that it "drapes" over radiator 396. On its bottom, tank
416 includes two
downwardly-extending sections 418, 420 that provide an increased fuel capacity
to fuel tank 416.
Depending upon the height of radiator 396, the amount of fuel 422 that may be
contained in tank
416 may be significantly increased. In the embodiment shown, height 424 is
approximately 17
mm.
Because the frame assembly 84 is designed to absorb and transfer energy for
the frame,
the thickness of left engine cradle wall 393 and right engine cradle wall 174
need not be as great
as was required in the prior art construction (see, e.g., Fig. 4).
Specifically, the construction of
the engine cradle 56 in the prior art required a plate thickness of
approximately 2.58 mm. With
26
CA 02350285 2001-06-12
the frame assembly 84, however, the plate thickness for engine cradle 394 may
be reduced to less
than about 2.5 mm. More preferably, the thickness may be reduced to about 2.0
mm, which
results in a significant weight savings.
In addition, engine cradle 56 included a forward wall 57 that was an extruded
element so
that forward wall 57 would be thick enough and strong enough to withstand the
magnitude of
forces exerted upon it. With the construction of engine cradle 394, however,
front wall 206 does
not need to be a thick, extruded element. Instead, front wall 206 may be a
piece stamped from a
metal sheet, just like left side structure 408 and right side structure 410.
Similarly, engine cradle
bottom 207 may also be stamped from a sheet of metal. As shown in Figs. 30 and
32, the engine
cradle also includes a rear panel or wall or apron 900 that may be stamped
from a metal sheet.
The rear panel 900 extends from a rear portion of the engine cradle bottom 207
and is bent to
include a plurality of angled sections that extend from the engine cradle
bottom 207 to the tunnel
370.
Left footrest 166 and right footrest 168 are both provided with a number of
foot-gripping
elements 426. One of foot-gripping elements 426 is illustrated in enlarged
detail in Figs. 37 and
38. Foot-gripping element 426 is constructed as part of a hole 428 through the
foot rests 166,
168. On one side, a jagged element 430 with teeth 432 curves upwardly from
footrest 166, 168.
On the other side, a deflector element 434 curves downwardly.
Foot-gripping elements 426 provide traction for the feet of the riders because
they extend
upwardly from the top surface of foot rests 166, 168. The top of each jagged
portion 430
includes teeth 432 that provide increased traction for the rider's feet.
Deflector element 434 at
the other side of hole 428 preferably deflects snow or dirt particles 436 that
may be stirred up by
the movement of the vehicle over the ground. If a particle 436 moves toward
the bottom of foot
27
CA 02350285 2001-06-12
rests 166, 168, in the direction shown by arrow 438, deflector element 343
will deflect particle
436 so that it travels in the direction shown by arrow 440, which is away from
hole 428. As a
result, particulate material 436 is discouraged from passing through hole 428
and accumulating
on the top of foot rests 166, 168.
To construct foot-gripping elements, 426, it is preferred that jagged portions
430 and
deflector portion 434 be stamped from footrest 166, 168 at the same time.
Jagged portion 430
may be bent upwardly and deflector portion 434 may be bent downwardly so that
the two
portions of foot-gripping element are in the preferred orientation. It is
preferred that deflector
portion 434 be forward of hole 428 and that jagged portion 430 be rearward of
hole 428. This
minimizes the potential for particles 436 to pass through hole 428 and
accumulate on the top
surface of footrests 166, 168.
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.
28
