Note: Descriptions are shown in the official language in which they were submitted.
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SNOWMOBILE
BACKGROUND AND SUMMARY
[0001]
The present disclosure relates to snowmobiles, and more particularly, the
present disclosure relates generally to the frame assembly, suspension
assembly,
cooling system and air intake system for snowmobiles.
[0002]
One of the performance characteristics of all vehicles, including
snowmobiles, includes the noise, vibration and harshness, the so-called NVH of
the
vehicle. This includes the comfort of the ride, and depends on a variety of
systems and
components, including the snowmobile suspension. Typically, a snowmobile
suspension includes two systems, a front suspension system for a pair of skis
and a
rear suspension system for the track.
[0003]
The front suspension of the snowmobile is coupled to the chassis of the
snowmobile and to steerable skis. The front suspension may include one or more
suspension arms on each side of the snowmobile.
[0004] The rear suspension of a snowmobile supports an endless track driven
by
the snowmobile engine to propel the machine. The track is supported beneath a
vehicle
chassis by a suspension that is designed to provide a comfortable ride and to
help
absorb the shock of the snowmobile crossing uneven terrain.
Most modern
snowmobiles use a slide rail suspension which incorporates a pair of slide
rails along
with several idler wheels to support the track in its configuration. The slide
rails are
typically suspended beneath the chassis by a pair of suspension arms, with
each arm
being attached at its upper end to the chassis of the snowmobile, and at its
lower end to
the slide rails.
[0005]
Noise of the vehicle is also a factor. Intake noise has been a concern for
snowmobile designs, and includes the intake noise, that is, the noise from the
engine
caused by the rush of air flow into the combustion chambers of the engine.
Some
attempts to control the intake noise are done through air intake silencers.
Recent
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designs have become larger and more complicated and it has become difficult to
further
reduce intake noise due to a lack of volume available in the engine
compartment.
[0006] Continued development of snowmobile platforms and the high
performance 2-stroke engines that power them have driven platform architecture
.. towards smaller, lighter and more compact integrated systems. As
manufacturers push
for lighter and smaller vehicles, the engine area space in the snowmobile
engine
compartment becomes increasingly limited, requiring efficient utilization of
non-
traditional packaging limitations. One of the areas requiring re-design is the
highly tuned
and critical 2-stroke exhaust pipe.
[0007] In one embodiment, a snowmobile comprises a chassis, comprising a
front chassis portion and a rear chassis portion; an engine positioned in the
front
chassis portion and having at least one intake port and at least one exhaust
port; a front
body portion defined over the front chassis portion and defining an engine
compartment;
a plenum assembly coupled to the front chassis portion and having at least one
intake
.. air vent and at least one air exit opening; and at least one duct coupled
to the air exit
opening and communicating air to the air intake, the duct being at least
partially
comprised of a porous material, whereby sound from the air intake is
dissipated in the
engine compartment.
[0008] In another embodiment, a snowmobile comprises a chassis,
comprising a
.. front chassis portion and a rear chassis portion; an engine positioned in
the front
chassis portion and having at least one intake port and at least one exhaust
port; a front
body portion defined over the front chassis portion and defining an engine
compartment,
at least one portion of the front body portion being fixed relative to the
front chassis and
at least one other portion being movable relative to the front chassis; at
least one air
vent positioned in the fixed front body portion; and an air intake system
coupled to the at
least one air vent and communicating air through the front body portion to the
engine
intake port, at least one portion of the air intake system being at least
partially
comprised of a porous material, whereby sound from the air intake is
dissipated through
the porous material and into the engine compartment.
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[0009]
In another embodiment, a snowmobile comprises a chassis; an engine
supported by the chassis; a front suspension coupled to the chassis and to
steerable
skis; the front suspension comprising at least one suspension arm; and
couplings
coupling the at least one suspension arm to the chassis, the couplings
comprising a
movable portion mountable to the chassis in multiple lateral positions,
relative to the
suspension arm for accommodating wear.
[0010]
In yet another embodiment, a snowmobile comprises a chassis including a
bulkhead and a tunnel; an engine supported by the chassis; a coupler attached
to the
chassis having plural connection points for coupling plural frame braces to
the tunnel.
[0011] In a further embodiment, a snowmobile comprises a chassis, having a
tunnel, an engine cradle and a bulkhead; an engine supported by the chassis; a
drive
belt supported by the chassis; a drive assembly for driving the drive belt,
comprising a
jack shaft driven by the engine and a drive shaft for driving the belt; a
portion of the
chassis including an integrated casing for receiving the jack shaft and drive
shaft
therein, and for enclosing sprockets attached to the jack shaft and drive
shaft.
[0012]
In yet another embodiment, a snowmobile comprises a chassis; a water
cooled engine supported by the chassis; and a cooler, the cooler comprising: a
top wall,
a lower wall, internal ribs connecting the top and lower wall and defining
channels, an
opening in one of the channels, an insert having an inlet port, an outlet port
and a
separating rib, the insert being positioned in the opening with the separating
rib
separating the one channel into two divided channel portions, the inlet port
communicating with a first divided channel portion and the outlet port
communicating
with a second divided channel portion, and
side walls positioned between the top
and lower wall and enclosing the channels.
[0013] In yet another embodiment, an exhaust pipe, comprises a diffuser, an
expansion chamber, a rear cone, and a stinger tube extending into the rear
cone,
wherein the stinger tube and rear cone are curved, with centerlines of the
stinger tube
and rear cone being concentric.
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[0013a] In yet another embodiment, a snowmobile comprises: a chassis,
comprising a front chassis portion and a rear chassis portion; an engine
positioned in
the front chassis portion and having at least one intake port and at least one
exhaust
port; a front body portion defined over the front chassis portion and defining
an engine
compartment; a plenum assembly coupled to the front chassis portion and having
at
least one intake air vent and at least one air exit opening; and at least one
duct coupled
to the at least one air exit opening and communicating air to the at least one
intake port,
the at least one duct including a wall extending from a first end of the at
least one duct
to a second end of the at least one duct, and the entirety of an exterior-most
surface of
the at least one duct is exposed to the engine compartment, the wall of the at
least one
duct being comprised of a molded porous material from the first end to the
second end
such that an interior surface of the molded porous material forms an interior-
most
surface of the at least one duct and an exterior surface of the molded porous
material
forms the exterior-most surface of the at least one duct, whereby sound from
the air
within the at least one of the plenum assembly and the at least one duct is
dissipated
in the engine compartment.
[0013b] In yet another embodiment, a snowmobile comprises: a chassis,
comprising a front chassis portion and a rear chassis portion; an engine
positioned in
the front chassis portion and having at least one intake port and at least one
exhaust
port; a front body portion defined over the front chassis portion and defining
an engine
compartment, at least one portion of the front body portion being fixed
relative to the
front chassis portion and at least one other portion being movable relative to
the front
chassis portion; at least one air vent positioned in the fixed front body
portion; and an
air intake system comprising at least one duct, the air intake system coupled
to the at
least one air vent and communicating air through the front body portion to the
at least
one intake port through the at least one duct, the entirety of an exterior-
most surface of
the at least one duct is exposed to the engine compartment, and the exterior-
most
surface of the at least one duct and an interior-most surface of the at least
one duct is
formed of a porous material, whereby sound from the air intake system is
dissipated
through the porous material of the at least one duct and into the engine
compartment.
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[0014] An illustrative embodiment will now be described by way of
reference to
the drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows a left front perspective view of a snowmobile
according to
the present embodiment;
[0016] FIG. 2 is a right rear perspective view of the snowmobile of
FIG. 1;
[0017] FIG. 3 is a left side view of the snowmobile of FIG. 1;
[0018] FIG. 4 is a right side view of the snowmobile of FIG. 1;
[0019] FIG. 5 is a top view of the snowmobile of FIG. 1;
[0020] FIG. 6 is a front view of the snowmobile of FIG. 1;
[0021] FIG. 7 is a rear view of the snowmobile of FIG. 1;
[0022] FIG. 8 is a rear fragmented view of the operator's area showing
a rear
side of the air intake system;
[0023] FIG. 9 is a left front perspective view of the air intake
system shown
removed from the snowmobile;
[0024] FIG. 10 is left rear perspective view of the air intake system
shown
removed from the snowmobile;
[0025] FIG. 11 is left front perspective view of the air intake system
shown in an
exploded manner;
[0026] FIG. 12 shows a perspective view of the ducts of the air intake
system;
[0027] FIG. 13A shows an exploded view of one of the ducts shown in
FIG. 12;
[0028] FIG. 13B shows an exploded view of the other of the ducts shown
in FIG.
12;
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[0029] FIG. 14 shows a rear view of the air intake system showing the
air vents;
[0030] FIG. 15 shows a portion of the snowmobile frame;
[0031] FIG. 16 shows a view of the snowmobile frame of FIG. 15,
showing the
frame components exploded away from a frame coupler;
[0032] FIG. 17 shows the frame coupler of FIG. 16 in greater detail;
[0033] FIG. 18 shows a rear perspective view of the rear suspension
and cooling
system;
[0034] FIG. 19 shows an underside perspective view of the rear cooler;
[0035] FIG. 20 shows a view similar to that of FIG. 18, in an exploded
manner;
[0036] FIG. 21 shows a left front perspective view of the cooler;
[0037] FIG. 22 shows an exploded view of the cooler of FIG. 21;
[0038] FIG. 23 shows a cross-sectional view of the cooler through
lines 23-23 of
FIG. 21;
[0039] FIG. 24 shows a cross-sectional view of the cooler through
lines 24-24 of
FIG. 21;
[0040] FIG. 25 shows a left side view of the front suspension;
[0041] FIG. 26 shows a left side view of the upper and lower
suspension arms;
[0042] FIG. 27 shows an exploded view of the upper suspension arm in
an
exploded view;
[0043] FIG. 27A is an enlarged view of a portion of the components shown in
FIG. 27;
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[0044] FIG. 28 shows a cross-sectional view of the coupler through
lines 28-28
of FIG. 26;
[0045] FIG. 29 shows a right side perspective view of the transfer
case;
[0046] FIG. 30 shows a view similar to that of FIG. 29, with the
transfer case
cover removed;
[0047] FIG. 31 shows a view similar to that of FIG. 30 with the gears
removed;
[0048] Fig. 32 shows a perspective view of an exhaust pipe according
to the
present disclosure;
[0049] Fig. 33 shows a side view of the exhaust pipe of Fig. 32; and
[0050] Fig. 34 shows the stinger portion of the exhaust pipe of Fig. 32.
DETAILED DESCRIPTION OF THE DRAWINGS
[0051] For the purposes of promoting an understanding of the
principals of the
invention, reference will now be made to the embodiments illustrated in the
drawings,
which are described below. The embodiments disclosed below are not intended to
be
exhaustive or limit the invention to.the precise form disclosed in the
following detailed
description. Rather, the embodiments are chosen and described so that others
skilled
in the art may utilize their teachings. It will be understood that no
limitation of the scope
of the invention is thereby intended. The invention includes any alterations
and further
modifications in the illustrative-devices and described methods and further
applications
of the principles of the invention which would normally occur to one skilled
in the art to
which the invention relates.
[0052] With reference first to FIGS. 1-7, a snowmobile is shown at 2
to generally
include a front outer body 4, a frame 6, an operator's seat 8, a propulsion
system 10
(FIG. 3) coupled to the frame 6, an endless track 12 coupled to the propulsion
system
10 for driving the snowmobile, and a steering system 14 coupled to steerable
skis 16.
The snowmobile 2 further comprises an air intake system 20 (FIG. 2) coupled to
an
engine of the propulsion system 10, and front 24 and rear 26 suspensions.
Snowmobile
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2 further includes left and right footrests 30 and 32 (FIG. 5) for the
placement of the left
and right feet of a driver while riding. Snowmobile 2 further includes a
cooling system
including a rear cooling portion 40 (FIG. 4). Cooling system of snowmobile 2
is similar
to that shown in US Patent 8,567,546. Snowmobile 2 further includes a
snowmobile
drive system 42 (HG. 29).
[0053] With respect to FIGS. 8-14, air intake system 20 will be
described in
greater detail. With reference first to FIGS. 8 and 9, air intake assembly 20
is shown
incorporated into the body styling. That is, the front outer body 4 includes
an upper
body panel 46 (FIG. 9), rear panel 52, side panel 54, and hood 56. The air
intake
assembly 20 including a plenum assembly 50, which intersects with rear panel
52, side
panel 54, and hood 56 in a cohesive fashion, and is partially defined by upper
body
panel 46. Plenum assembly 50 includes air intake vents 60 as described further
herein.
The upper body panel 46, rear panel 52, and side panel 54, are fixed relative
to the
chassis or frame 6, whereas hood 56 is movable relative to frame 6 to access
an engine
compartment.
[0054] As shown best in FIG. 10, plenum assembly 50 includes a rear
edge 66,
which conforms to panel 52 as best shown in FIG. 8. Plenum assembly 50
includes
integral brackets at 70 on either side thereof for mounting plenum assembly 50
to the
snowmobile frame. A slot 72 is provided to allow access for a steering post of
steering
assembly 14.
[0055] With reference now to FIG. 11, plenum assembly 50 is shown as
having
an upper plenum housing 80 and a lower plenum housing 82. Upper plenum housing
80 includes a front wall 84 defining a lower peripheral edge 86. Lower plenum
housing
82 includes a perimeter wall 90 defining an upper plenum edge at 92. It should
be
appreciated that walls 84 and 90 complement each other with edges 86, 92
conforming
to provide a sealed plenum housing when coupled together. As shown in FIG. 11,
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fasteners such as 96 are provided, which are received through lower plenum
housing
82 to be received in threaded bosses on an underside of upper plenum housing
80.
Lower plenum housing 82 includes an air exit port 100 having an opening at 102
as
described herein. It should be appreciated that once coupled together, upper
and lower
plenum housings 80, 82 provide for a closed air box with the only intakes
being
provided by vents 60 and the only air exit being provided by opening 102. That
is,
passageways 104 are created that channel air forwardly from vents 60 to
opening 102.
[0056] With reference now to FIGS. 9 and 10, the entire air intake
system 2- is
shown where plenum 50 is shown coupled to a first duct 120, which is coupled
to a
second duct 122, which in turn, is coupled to air box 124. Ducts 120 and 122
will be
described in greater detail with reference to FIGS. 12, 13A and 13B. As shown
in FIG.
12 and 13B, duct 120 includes a molded porous duct portion 130 coupled to a
molded
porous duct portion 132. As shown, duct portion 130 includes integrated
mounting tabs
134, which provide apertures 136 for mounting to lower plenum housing 82. More
.. particularly, and as shown in FIG. 11, fasteners 138 are receivable in
apertures 136,
which may then be received in threaded bosses 140 of lower plenum housing 82.
Duct
120 defines a first opening at 144 (FIG. 12), which corresponds to opening 102
of lower
plenum housing 82. A seal may be positioned between openings 102, 144 to
better
seal the interconnection between the interface of openings 102, 144. Duct 120
further
defines an opening at 150 (FIG. 12), which couples to duct 122. Opening 150 is
provided with a surrounding latching component 152 having a ramped surface,
thereby
providing a locking edge when inserted into duct 122 as shown herein.
[0057] Duct 122 is better shown in FIG. 13A as having a molded porous
duct
portion 160 and a molded porous duct portion 162. Porous portion 160 includes
an
opening at 164 to couple with opening 150 on duct 120 and opening 166 to
couple with
air box 124. Opening 166 is defined by a molded polyethylene portion
ultrasonically
welded to the porous portion. It should be understood that either duct could
include a
molded portion (polyethylene or other material) coupled to the porous portion
in order to
rigidify the duct in any place required. As shown, duct portion 160 includes
an outer
peripheral flange at 170 and duct portion 162 includes an outer peripheral
flange at 172,
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which is complementary to flange 170. Duct portions 160 and 162 can therefore
be
coupled, for example, by sonic welding at the flanges 170 and 172.
[0058] With reference now to Figs. 11 and 12, air box 124 will be
further
described. Air box 124 Includes an upper housing portion 180 and a lower
housing
portion 182. Upper housing portion 180 includes intake opening at 184 and
lower
housing 182 includes openings 186, which would be coupled to throttle bodies
of the
snowmobile engine. Duct 122 would be coupled to air box 124 by way of fastener
190
(FIG. 12) attached to threaded boss 192. Air box 124 would include therein an
air filter
as is known in the art.
[0059] The operation of the air intake system 20 will now be described. As
mentioned before, and with reference to FIG. 14, air vents 60 allow air to
enter plenum
50 of air intake system 20. Air enters the vents 60 and continues into plenum
50. Air
exits plenum 50 through opening 102 (FIG. 11) and continues into duct 120. Air
exits
duct 120 and enters into duct 122 whereupon it enters air box 124. Air exits
openings
186 where it is connected to throttle bodies (not shown) and enters through an
air intake
side of an engine. As the outside portions 132, 162 of ducts 120 and 122 are
comprised of a porous material, the sound at the operator's station through
the vents is
eliminated because the sound is dissipated through the porous material in the
engine
compartment. Furthermore, the vents face rearwardly towards a rider, but are
angled
outwardly.
[0060] Thus, the vents can be placed along a fixed portion of the
snowmobile
body without undue sound effects to the operator. For example, most
snowmobiles
have the engine air intake attached to the hood, which requires a seal between
the
hood and intake duct. This seal is violated every time the hood is opened
requiring
correct placement of the hood over the intake duct. This design also
eliminates
additional resonators and/or Hemholtz boxes in the engine compartment allowing
increased volume for other essential engine components.
[0061] It has been found that the best performance is achieved where
the
material of duct portions 132 and 162 have a porosity of 30%; however, the
sound
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dissipation is substantially improved with porosity within the range of 20-
40%. Suitable
materials for the porous materials could include ultra-high molecular weight
polyethylene (UHMWPE), polyester (PET) + polypropylene (PP), high-density
polyethylene (HDPE), polypropylene (PP), polytetrafluoroethylene (PTFE), and
polyvinylidene fluoride (PVDF). Ethylene vinyl acetate (EVA), polyethersulfone
(PES),
polyurethane (PU) and PE/PP co-polymer could also be used. In the embodiment
shown, the material chosen is a polyester (PET) + polypropylene (PP).
[0062] As shown best in Figs. 15-17, a portion of the frame will now
be described
in detail. As shown best in FIG. 15, a frame coupler 200 is shown providing
coupling
attachment to multiple components. As shown in FIG. 15, frame 6 is shown as
including a tunnel 202 having a top wall 204 and sidewall 206 to which foot
rest 30 is
attached. Engine cradle 208 extends forwardly from tunnel 206. Toe clip 210
extends
forwardly from footrest 30 and is rigidified by a brace at 212. A mainframe
tube 216
extends upwardly to a steering arm and brace 218 extends forwardly to another
frame
component.
[0063] As shown in Figs. 16 and 17, coupler 200 includes an upwardly
extending
tubular connection at 220; a downwardly extending tubular coupler at 222; a
forwardly
extending tab 224; and an L-bracket at 226. L-bracket 226 includes a
horizontal bracket
portion 228 and a vertical bracket portion 230. As shown in FIG. 16, coupler
200 is
coupled to tunnel 202 by way of fasteners 240 (FIG. 16) through apertures 242
(FIG.
17) and into apertures 244 (FIG. 16) on tunnel sidewall 206. Fastener 250 is
received
through aperture (FIG. 17) 252 and through aperture 254 (FIG. 16) on tunnel
top wall
204. Tube 212 can thereafter be received in opening 222a of coupler 222 (FIG.
17) and
fastener 260 can be received through aperture 262. In a like manner, tube 216
can be
positioned in opening 220a of coupler 220 and fastener 266 can be received
through
aperture 268. It should be appreciated that the coupling of tubes 212 and 216
into
corresponding opening 222a and 220a could include the use of a bonding
adhesive.
Finally, strut 218 can be coupled to tab 224 by way of fasteners 280, 282
(FIG. 16).
Thus coupler 200 allows for the coupling of multiple different frame
components, even
different sized tubes 212, 216.
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[0064] With reference now to Figs. 18-24, the rear cooling portion 40
will be
described in greater detail. As shown in Figs. 19-20, the rear cooling portion
40
includes a rear cooler 300, which is shown coupled to a rear control arm 302
of rear
suspension. Rear control arm 302 includes lower couplings at 304 attached to
upright
tubes 306, which couple with brackets 308. Each bracket includes spaced apart
plates
310 having apertures 312 there through. A rear bumper 320 is provided having
forwardly extending tubes 322 having apertures 324. An insert spacer 330 is
provided
having apertures at 332. Cooler 300 includes threaded bosses 350 and 352,
which are
aligned with apertures 312. Rear snow flap 370 includes an upper cover portion
372
and sidewalls at 374, sidewalls 374 including clearance opening at 376.
[0065] Rear cooler 300 is assembled to rear control arm 302 by
installing insert
spacers 330 into the end of tubes 322 to align apertures 324 and 332. Tubes
322 are
then positioned intermediate plates 310 of bracket 308 and fasteners 380 may
be
inserted through apertures 312, 332 and 324. Rear flap 370 is then positioned
over
cooler 300 with apertures 376 aligned with apertures 350 and 352. Apertures
350 and
352 are then aligned with fasteners 380; and fasteners 380 may be inserted and
threadably received in threaded bosses 350 and 352. As shown best in FIG. 21,
a
portion of threaded boss extends beyond an end of the cooler 300, which
defines end-
faces 350a and 352a protruding from a side edge of the cooler 300. Thus, end
surfaces
350a and 352a project through apertures 376 and may be flushly received
against side
surface 310a (FIG. 20) such that bracket 308 is fixed firmly against cooler
300 with
apertures 376 only providing clearance for bosses 350, 352. A rear flap 390
may be
attached to rear snow flap 370 by way of fasteners through corresponding
apertures
392, 394 and 396, 398.
[0066] With reference now to Figs. 21-24, cooler 300 will be described in
greater
detail. Cooler 300 is generally comprised of an extrusion extruded along an
axis 400.
The extrusion defines internal ribs 404, 406 and 408, defining channels 410A,
410B,
412, 414, and 416. The extrusion process also defines a plurality of fins at
418. As
shown best in FIG. 22, cooler 300 includes an insert at 430 defining an inlet
at 432, an
outlet at 434 and a separating rib 436 (see Figs. 23 and 24) intermediate the
inlet 432
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and outlet 434. Insert 430 further includes a top plate 440 and a front plate
442. An
opening 444 may be cut in cooler 300 to receive insert 430 whereby divider rib
436 is
positioned in channel 410 dividing the channel into inlet and outlet portions
410A, 410B.
As shown in FIG. 24, portions of the ribs 404, 406, and 408, are cut away at
404a,
406a, and 408a (at each end) thus defining passageways between each of the
channels.
[0067] Therefore, and with reference still to FIG. 24, water may flow
into channel
410A and into any of channels 412, 414, or 416, and be returned to channel
410B and
exit through outlet 434 (FIG. 22). End plates 460 may be positioned into
openings 462
and held in place by adhesive or welding or any other means known in the art.
[0068] With reference now to FIGS. 25-28, front suspension 24 will be
described
in greater detail. Front suspension 24 is similar to the front suspension
shown and
described in US Patent 8,225,896.
[0069] With reference first to FIG. 25, snowmobile 2 includes a front
bulkhead
500 comprised of mirror image cast members 502, 504. The front suspension 24
is
coupled to bulkhead 500. For example, front suspension 24 includes an upper A-
arm
506 and a lower A-arm 508 each of which is coupled to the left Cast member
502.
Counterpart A-arms similar to 506, 508 (shown in FIG. 2) are coupled to
casting 504.
Upper A-arm 506 and lower A-arm 508 are coupled by their outer ends to a
spindle 510
(FIG. 1) which in turn couples to steerable ski 16. Upper A-arm 506 has inner
couplings
512, 514 coupled to casting 502 and lower A-arm 508 has inner couplings at
516, 518
coupled to casting 502. Couplings 512, 514, 516 and 518 are coupled to casting
502
by way of fasteners 520 such as bolts or studs, and nuts.
[0070] With reference now to Figs. 26, 27, and 27A couplers 512, 514
will be
described in greater detail. As shown, coupler 512 includes a coupling tube
520, sleeve
522, thrust washer 524 and coupling arm 526. As shown, coupling tube 520
includes
an inner diameter 530 and an outward edge at 532. Sleeve 522 includes a
cylindrical
portion 540 having an outer diameter at 542 and an inner diameter at 544.
Sleeve 522
includes an outer lip 550 having an inner surface 552 and an outer surface
554. Arm
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526 includes a center cylindrical portion 560 having flat surfaces 562 at one
end and
flat surfaces 564 at the opposite end. Thrust ring or lip 566 is positioned
between the
flat surface of 564 and cylindrical portion 560 and includes a thrust surface
568. Arm
526 further includes slotted openings 570 at one end and slotted openings 572
at the
opposite end. Cylindrical portion 560 includes outer diameter at 576. Thus
openings
570 and 572 are elongated in.the longitudinal direction of arm 526, or along
axis 580
(FIG. 27A). It should be appreciated that coupler 514 is identical in assembly
components, that is including sleeve 540, washer 524 and arm 526, the
components
however are simply reversed as that described above with reference to coupler
512 as
will be described herein.
[0071] As shown in Figs. 27A and 28, sleeve 540 is positioned in
coupling tube
520 with outer surface 542 positioned within opening 530 of coupling tube 520.
Inner
surface 552 of sleeve lip 550 abuts outer surface 532 of coupling tube 520.
Arm 526 is
positioned within sleeve 540 with outer diameter 576 positioned against inner
diameter
544 of sleeve 540 and with thrust washer 524 positioned intermediate surfaces
554
(FIG. 27A), and 568. Thus as any of the surfaces 568, 524A, 524B, 554, 552 or
532
begin to wear, fasteners 520 (FIG. 25) may be loosened and arm 526 may be
moved
to the right or in the direction of arrow 590 as shown in FIG. 27. The same
goes for
coupler 514 whereby arm 526 may be moved in the direction of arrow 600 as
shown in
FIG. 2T However, in the embodiment shown, the thrust washer has a lower
hardness
than the sleeve 540 and the arm 526, such that the wear is defined at the
thrust washer.
The wear could be defined at the sleeve, by having the sleeve hardness lower
than the
arm 26 and washer 524.
[0072] With reference now to FIGS. 29-31, the snowmobile drive system
42 will
be described in greater detail. It should be appreciated snowmobile drive
system 42 is
similar to that disclosed in US Publication 20130032419.
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[0073] With reference first to FIGS. 29-30, front bulkhead 500 is
shown coupled
to a snowmobile front frame portion 208, also referred to as an engine cradle,
which
includes frame portion 650 extending forwardly from snowmobile tunnel 202. The
frame
portion 650 supports a first drive member 654 including pulley 655 (FIG. 29)
which is
coupled to driveshaft 656 (FIG. 30) which in turn drives a driveshaft 658.
Driveshaft 658
is coupled to driveshaft 656 by way of sprockets 660 and 662 driven through
chain 664.
[0074] As shown best in FIGS. 30 and 31, frame portion 650 includes a
forwardly
extending leg portion 700 having a gear casing 702 coupled to a rear end
thereof, and a
mounting bracket 704 at a front end thereof. Casing 702 includes a peripheral
wall 706
which defines an inner volume to the casing forward of a rear wall 708.
Apertures 710,
712 extend through wall 708 and form openings for jackshaft 656 and driveshaft
658.
Casing 702 defines a volume for receiving gears 660, 662 as shown best in FIG.
30.
Casing 702 includes a plurality of bosses 716, as described herein.
[0075] A cover 720 has a peripheral edge 722 having a geometry which
coincides with wall 706. Cover 720 includes an inner groove 724 for receiving
a seal to
receive an edge of wall 706 therein for a sealed connection therewith. Cover
720
further provides a plurality of bosses 726 which correspond with bosses 716
for
receiving fasteners 728 there through. Cover 720 further provides an opening
730
corresponding to opening 710, providing access for a brake disc 740 mounted to
shaft
656.
[0076] With reference now to Figs. 32-34, a new exhaust pipe will be
described in
greater detail. As shown, an exhaust pipe is shown at 800 having an inlet 802
and an
outlet at 804. Exhaust pipe 800 includes an outer tube 806 and an internal
stinger tube
at 808. As shown in Figs. 32 and 33, internal stinger tube 808 is curved along
an axis
symmetric with the outer tube 806. Components of the outer tube include a
header 810,
reverse bend 812, diffuser 814, expansion chamber 816, and rear cone 818.
[0077] An internal stinger in a 2-stroke tuned pipe serves multiple
purposes. Both
to provide an area change for wave reflection and to create an artificial
baffle in the
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convergent tail cone of the pipe serving to reduce the sound output both in
absolute
intensity and in frequency.
[0078] High performance 2-stroke engines have, historically, featured
an
axisymnnetric convergent rear cone with a stinger concentric with the rear
cone
centerline axis. The reduction in both the overall engine area space and the
longitudinal
distance of the front section of the vehicle chassis will eliminate the
ability to include a
straight, concentric stinger design with an acceptable rear convergent cone
length.
[0079] As shown herein, a curved, either as single radius or a
compound, multi-
dimensional bend allows integration of an internal stinger of sufficient
length which is
concentric with the convergent rear cone at any given centerline position.
This allows for
both the sound damping capabilities of the internal stinger as well as the
reflection and
wave dynamic requirements of the convergent rear cone to co-exist within a
smaller
overall vehicle package.
[0080] Utilizing a curved or compound 3-dimensional bent internal
stinger allows
for the stinger to remain concentric with the rear cone centerline allows
effective use of
the sound reduction capabilities of the stinger and the wave dynamic
requirements of
the rear cone without introducing non symmetric, 2 dimensional localized gas
flow and
wave reflection within the tuned pipe rear cone.
[0081] The curved internal stinger can be made either from bent
tubing; with or
without formed ends for joining to the convergent cone or multi-angle 3-
dimensional
resolved geometry made in two halves (see Fig. 34) and seam joined along side
edges
820. The utilization of multi-angle, multi-dimensional complex geometry in
tuned pipe
cone design as subsequently stinger design will permit smaller vehicles and
more
compact packaging.
[0082] The use of this type of internal stinger will help achieve
acceptable sound
levels without the need to compensate for the lack of a stinger with the
utilization of
larger silencers and/or increasing numbers of silencer resonant chambers.
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[0083] Furthermore, non-axisymmetric stinger design, which allows for
a stinger
which is concentric with the rear cone at any given position, attains more
consistent
thermal gradients along both the centerline and the radial distance at a given
axis
position. This creates more predictable performance, frequency response and
operational characteristics.
[0084] While this invention has been described as having an exemplary
design,
the present invention may be further modified within the spirit and scope of
this
disclosure. This application is therefore intended to cover any variations,
uses, or
adaptations of the invention using its general principles. Further, this
application is
intended to cover such departures from the present disclosure as come within
known or
customary practices in the art to which this invention pertains.
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