Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02588356 2007-05-11
SNOWMOBILE PLANETARY DRIVE SYSTEM
CROSS REFERENCE To RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent application
Serial
No. 10/859,394, filed November 4, 2004, which is a divisional of U.S. patent
application
Serial No. 09/966,926, filed with the United States Patent and Trademark
Office on
September 27, 2001, which is a continuation-in-part of U.S. patent application
Serial No.
09/843,587 that was filed with the United States Patent and Trademark Office
on April 26,
2001, which is a continuation-in-part of U.S. patent application Serial No.
09/520,101, filed
with the United States Patent and Trademark Office on March 7, 2000. The
entire disclosures
of U.S. patent application Serial Nos. 10/859,394, 09/843,587, 09/520,101 and
09/966,926
are incorporated herein by reference.
-1-
CA 02588356 2007-05-11
FIELD OF THE INVENTION
[0002] The present invention relates to snowmobiles and more particularly to
drive
systems for snowmobiles. More particularly, the present invention relates to
snowmobiles
including various embodiments of drive systems utilizing planetary gears.
BACKGROUND OF THE INVENTION
[0003] Snowmobiles have been known for many years. Early snowmobiles were
developed with an appearance that is very primitive compared to the snowmobile
of today.
The snowmobile of modem times is a sophisticated vehicle with heated hand
grips, twin head
lights, high powered engines, and many other improvements not found in the
original
snowmobiles.
[0004] One of the weak points in snowmobiles has been the drive system.
Snowmobile drive systems have generally included a chain rpm reduction drive.
The rpm of
the engine must be reduced prior to applying the rotational drive to the
differential sprockets
driving the track. In the past, the drive system has included a chain and
sprocket system. The
chain and sprocket system tends to wear and is subject to extreme abuse in the
activities of
normal snowmobile use. The rapid starts and stops, the very high rpm torque
when the
snowmobile leaves the ground and leaps into the air results in extremely rapid
changes of
speed and load.
[0005] It is also sometimes desired to include in the drive system a reverse
unit for
propelling the snowmobile in reverse direction under power of the engine.
Reverse units of
snowmobiles to date have achieved only low to moderate effectiveness. In
particular, such
units usable with four-stroke engines have been very heavy involving
complicated shifting
and gearing mechanisms. They have also been difficult to use including
cumbersome
engagement mechanisms.
-2-
CA 02588356 2007-05-11
SUMMARY OF THE INVENTION
[0006] A drive system includes a continuously variable transmission (CVT)
coupled to a drive shaft of an engine. The CVT includes a drive clutch driven
by the drive
shaft and a driven clutch driving a propulsion member such as an endless track
of a
snowmobile. The clutches are interconnected with a belt.
[0007] A planetary gear system is coupled between a continuously variable
transmission and one of said drive shaft and the vehicle propulsion member.
The planetary
gear system includes an input shaft rotatably secured to the frame and driven
by one of the
drive shafts and the driven clutch. A sun gear secures to the input shaft. An
output shaft
rotatably secures to the frame and drives either the drive clutch or the
propulsion member.
One or more planetary gears rotatably mount to a cage and engage the sun gear.
The
planetary gears likewise engage a ring gear encircling the planetary and sun
gears.
[0008J A coupler is selectively engageable between an output shaft of the
planetary
gear system and either the cage or the ring gear. A brake is movable between
engagement
with whichever of the cage and ring gear to which the coupler is not engaged.
[0009] In some embodiments, the coupler rotatably mounts to a brake embodied
as
a cylindrical slider such that the coupler is restrained from moving along an
axis of rotation
of the coupler. The coupler is slidable by the brake into engagement with one
of the cage and
the ring gear. The ring gear includes an outer toothed surface selectively
engaged with an
inner toothed surface secured to the coupler. The cylindrical slider also
includes an inner
toothed surface selectively engageable with the ring gear and the cage.
[0010] In some embodiments, the cylindrical slider and coupler engage the cage
by
means of first and second cage gears coupled to the cage to move synchronously
therewith.
The first cage gear is engageable with the inner toothed surface of the
cylinder and the
second cage gear is selectively engageable with the inner toothed surface of
the coupler. The
-3-
, CA 02588356 2007-05-11
planetary gears and ring gear are typically positioned between the first and
second cage
gears. 10.
[0011] In some embodiments, a detent mechanism engages at least one of the
brakes and the coupler to retain the brake and the coupler in either a first
position having the
brake engaged with the ring gear and the coupler engaged with the cage or a
second position
having the brake engaged with the cage and the coupler engaged with the ring
gear.
[0012] In one embodiment, the detent mechanism engages a coupler ring
rotatably
mounted to the cylindrical slider and a coupler hub rigidly mounted to the
output shaft. The
detent includes at least one spring loaded pawl having first and second ends,
the first end
engages the coupler hub and the second end engages the coupler ring. The first
end of the
pawl fits within an aperture formed in the coupler hub. A biasing member
positioned within
the aperture urges the pawl outwardly from the aperture.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Preferred and alternative embodiments of the present invention are
described in detail below with reference to the following drawings.
[0014] FIGURE 1 shows a snowmobile of the present invention;
[0015] FIGURE 2 shows a perspective view of the snowmobile engine and drive
system of the present invention;
[0016] FIGURE 3 shows a plan view of a chassis including an engine, clutch
system and the planetary drive system of the present invention;
[0017] FIGURE 4 shows a sectional view of the planetary drive system of the
present invention;
[0018] FIGURE 5 shows an exploded view of the planetary drive system of the
present invention;
[0019] FIGURE 6 shows an alternative embodiment of the present snowmobile;
-4-
CA 02588356 2007-05-11
[0020] FIGURE 7 shows a plan view of a chassis of an alternative embodiment of
the present invention including an engine and the reduced rpm clutch system;
[0021] FIGURE 8 shows a sectional view of the planetary gear reduction system
of
an altemative embodiment of the present invention;
[0022] FIGURE 9 shows an exploded perspective view of a prior art drive train;
[0023] FIGURE 10 shows an exploded perspective view of a portion of the prior
art
drive train;
[0024] FIGURE 11 shows an exploded perspective view of the parts of a prior
art
drive train that are eliminated by one embodiment of the present invention;
[0025] FIGURE 12 is a perspective view of a engine and drive train according
to an
alternative embodiment of the present invention;
100261 FIGURE 13 is a portion of an alternative embodiment of a portion of
drive
train of the present invention;
[0027] FIGURE 14 is an exploded view of a further alternative embodiment of a
planetary gear system of the present invention;
[0028] FIGURE 15 is a sectional view of the planetary gear system shown in
FIGURES 12, 13 and 14;
[0029] FIGURE 16 is a sectional view of an alternative embodiment planetary
gear
system including a reverse unit shown in forward mode;
[0030] FIGURE 17 is a sectional view of an altemative embodiment planetary
gear
system including a reverse unit shown in reverse mode;
[0031] FIGURE 18 is a sectional view of an alternative embodiment offset in
combination with a planetary gear system including a reverse unit;
[0032] FIGURE 19 is a sectional view of an alternative embodiment offset in
combination with a planetary gear system;
-5-
CA 02588356 2007-05-11
[0033] FIGURE 20 is an exploded view of an alternative embodiment of a
planetary gear system;
[0034] FIGURE 21 is an exploded view of a planetary gear assembly suitable for
use in the planetary gear system of FIGURE 20;
[0035] FIGURE 22 is a perspective view of a planetary gear assembly suitable
for
use in the planetary gear system of FIGURE 20;
[0036] FIGURE 23 is an exploded view of a coupler suitable for use in the
planetary gear system of FIGURE 20;
[0037] FIGURE 24 is another exploded view of the coupler of FIGURE 23; and
[0038] FIGURE 25A-25C are side cutaway views of the planetary gear system of
FIGURE 20 in forward, reverse, and neutral positions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] FIGURES 1-8 are the original figures from the parent application Serial
No.
09/520,101 that were filed with the United States Patent and Trademark Office
on March 7,
2000. Some changes have been made to FIGURES 1-8 for clarification purposes.
FIGURES 9-15 are the figures added in the parent application Serial No.
09/843,587 that
were filed with the United States Patent and Trademark Office on Apri126,
2001. FIGURES
16-19 were added in the parent application Serial No. 10/859,394, filed
November 4, 2004.
[0040] The snowmobile 10 of the present invention (FIGURE 1-5) includes a pair
of skis 12, which support the forward portion 13 of the snowmobile 10. A
continuous track
14 supports the rear portion 16 of the snowmobile 10. The snowmobile 10 has an
engine 17,
which is disposed in the forward portion 13.
[0041] The engine 17 rotatably drives a train 18, which in turn drives the
endless
track 14. The drive train 18 includes an engine drive shaft 15, primary clutch
18a, a drive belt
18b, a secondary clutch 18c and a reduction drive 19. The reduction drive 19
may include a
drive shaft 21 that is rotatably driven by the secondary clutch 18c. The drive
shaft 21
-6-
CA 02588356 2007-05-11
(FIGURES 4 & 5) carries a sun gear 22, which is integral with said shaft 21.
Note that a "sun
gear" is any gear that drives a plurality of planetary gears. Also note, that
the "longitudinal
axis" of a shaft is the axis along the length of such shaft. The shaft 21 is
rotatably supported
in suitable bearings or bushings. Such bearings or bushings may be roller
bearings. The
embodiment shown in the figures depicts the use of single row ball bearings 23
and 24.
[0042] The reduction drive 19 further includes a plurality of planetary gears
26, 27,
28, and 29. The reduction drive 19 is shown having four planetary gears 26-29,
however, the
reduction drive may have any desired number of such gears, e.g., three. The
planetary gears
26-29 are supported between a pair of planetary gear plates 31, 32. The plates
31, 32 carry a
plurality of shafts 36, 37, 38 and 39 which rotatably support the gears 26-29
respectively.
The shafts 36-39 may be integrally secured to the plates 31, 32, which in turn
serve to
maintain said gears 26-29 in spaced relationship around the sun gear. Spacers
30 may retain
plates 31, 32 in proper spaced relationship. The shafts 36-39 are secured in
the openings 36a-
39a, respectively.
[0043] The reduction drive 19 includes a second shaft 43, which is integral
with the
plates 31, 32. In other words shaft 43 is locked by a key in the hub 31a.
[0044] The reduction drive 19 has a housing 40 including first housing member
41
and a second housing member 42. A ring gear 44 is integrally mounted in the
second housing
member 41. The ring gear 44 engages the planetary gears 26-29. The second
shaft 43 is
integral, e.g., in locked driving engagement, with the plates 31, 32 and is
driven by planetary
gears 26-29. The second shaft 43 serves to drive the endless track 14 through
sprocket 51.
[0045] The sun gear 22, planetary gears 26-29 and ring gear 44 are contained
in
housing 40 including first housing member 41 and second housing member 42. The
housing
members 41 and 42 may be held together by suitable screws 45.
[0046] The operation of the present invention is apparent from the description
of
the snowmobile 10, however in order to provide a more complete understanding
of the
-7-
, CA 02588356 2007-05-11
present invention the operation will be further described. The engine 17 may
be a
conventional gasoline powered engine of the type generally found in
snowmobiles. However,
the engine 17 may be any other type of engine suitable for driving a
snowmobile. The engine
17 rotatably drives the primary clutch 18a, which in turn drives the belt 18b.
The drive belt
18b may drive the secondary clutch 18c, which rotatably drives the shaft 21.
The sun gear 22
is then driven by the shaft 21. The sun gear 22 engages the planetary gears 26-
29 which are
rotatably supported in the plates 31, 32. The force of the sun gear 22 acting
on the planetary
gears 26-29 cause the gears 26-29 to rotate and move along the ring gear 44
thereby rotating
the plates 31, 32. The rotation of plates 31, 32 rotatably drive the second
shaft 43. The
second shaft 43 rotates at a rpm lower than the rotation of the first shaft 21
resulting in a gear
reduction. The second shaft 43 in turn drives a sprocket 51 acting on the
endless track 14,
thereby driving such track.
[0047] A further embodiment of the present invention snowmobile 110
(FIGURES 6-8) includes a pair of skis 112 which support the forward portion
113 of the
snowmobile 110. A continuous track 114 supports the rear portion 116 of the
snowmobile
110. The snowmobile 110 has an engine 117 which is disposed in the forward
portion 113.
100481 The engine 117 rotatably drives a power train 118, which in turns
drives the
endless track 114. The drive train 118 includes a planetary reduction gear
system 119, which
in turn drives a primary clutch 121, a drive belt 122, and a secondary clutch
123. The
planetary reduction drive system 119 may be mounted on the drive shaft 124 of
the engine
117. The planetary reduction drive system 119 may be similar in structure to
planetary
reduction drive system 19 shown in FIGURES 4 and 5. The planetary reduction
drive system
119 is rotatably driven by the engine drive shaft 124. The engine drive shaft
124
(FIGURES 7 & 8) drives a drive shaft 127 (also may be referred to as an input
shaft) that
carries a sun gear 126 that is integral with the engine drive shaft 124. The
engine drive shaft
124 may be rotatably supported in suitable bearings or bushings. Such bearings
or bushings
-8-
CA 02588356 2007-05-11
may be roller bearings. The embodiment shown in the figures depicts the use of
single row
ball bearing 125.
[0049] The reduction drive system 119 further includes a plurality of
planetary
gears 131. The planetary gears 131 are supported between a pair of planetary
gear plates 136,
137. The plates 136, 137 carry a plurality of shafts 141 which rotatably
support the gears 131
respectively. The shafts 141 may be integrally secured to the plates 136, 137,
which in turn
serve to maintain said gears 131-134 in spaced relationship around the sun
gear 126. A
plurality of spacers 138 may retain plates 136, 137 in proper spaced
relationship such that the
planetary gears 131 may freely rotate there between. The spacers 138 may be
integral with
respect to plates 136, 137.
[0050] The reduction drive 119 includes a second shaft 145, which is integral
with
respect to the plates 136, 137. Second shaft 145 is tapered to fit the primary
clutch 121. Of
course, any shape second shaft that is capable of driving the primary clutch
is within the
scope of the present invention.
[0051] The reduction drive 119 has a first housing member 151 and a second
housing member 152. A ring gear 154 is integrally mounted in the second
housing member
152. The ring gear 154 engages the planetary gears 131. The second shaft 145
is integral,
e.g., in locked driving engagement, with the plates 136, 137 and is driven by
planetary gears
131. The second shaft 145 serves to drive the primary clutch 121.
[0052] The sun gear 126, planetary gears 131 and ring gear 154 are contained
in
housing 150 including first housing member 151 and second housing member 152.
The
housing members 151 and 152 may be held together by suitable screws (not
shown).
[0053] The operation of the present invention including the reduced rpm clutch
is
apparent from the description of the snowmobile 110. The engine 117 may be a
conventional
gasoline powered engine. The engine 117 has an engine drive shaft 124, which
drives a sun
gear 126, which in turn drives a plurality of planetary gears 131. The sun
gear 126 engages
-9-
CA 02588356 2007-05-11
the planetary gears 131 which are rotatably supported in the plates 136, 137.
The force of the
sun gear 126 acting on the planetary gears 131 cause the gears 131 to rotate
and move along
the ring gear 154 thereby rotating the plates 136, 137. The rotation of plates
136, 137
rotatably drives the second shaft 145. The second shaft 145 rotates at an rpm
lower than the
rotation of the drive shaft 124 resulting in a gear reduction. The second
shaft 145 rotatably
drives the primary clutch 121, which in turn drives the belt 122. The drive
belt 122 drives the
secondary clutch 123. Clutch 123 rotatably drives the shaft 157, which carries
sprocket
drives 158 and 159. The sprockets 158, 159 drive the track 114.
[0054] Turning now to FIGURES 9-11, a conventional prior art snowmobile drive
system is shown. FIGURE 9 is an exploded perspective view of the major
components of a
prior art drive system including the engine. FIGURE 10 is an exploded
perspective view of
the portion of a prior art drive system from the secondary clutch to the track
drive sprockets.
FIGURE 11 is an exploded perspective view of the parts of the conventional
prior art drive
system of FIGURE 10 that may be eliminated by one embodiment of the present
invention.
[0055] The major components of the prior art drive system 270 shown in
FIGURE 9 are engine 272, primary clutch 274, engine drive shaft (not shown)
connecting the
engine 272 to the primary clutch 274, drive belt 276 (shown in partial cutaway
view),
secondary clutch 278, driven shaft 280, dropcase 282, drive chain 284, top
drive sprocket
286, bottom drive sprocket 288, dropcase cover 290, shaft 292 and track drive
sprockets 294
and 296.
[0056] FIGURE 10 includes the major components from the secondary clutch 278
to the track drive sprockets 294 and 296 as well as additional components of
the conventional
prior art drive train system 270.
[0057] The parts of a chain and sprocket rpm reduction drive of the prior art
are
subject to wear and tear and tend to require high maintenance. Furthermore,
the use of a
chain and sprocket reduction drive requires that the drive system, including
the engine drive
-10-
CA 02588356 2007-05-11
shaft, have three parallel shafts. For each shaft there must be associated
bearings and other
support parts associated therewith. The present invention advantageously
eliminates one of
the three shafts, in addition to the elimination of the chain and sprocket rpm
reduction drive.
100581 Transnzission of power through a rotating shaft results in shaft wind-
up.
Shaft wind-up is essentially a lag in the power transmission through the
shaft. The amount of
wind-up is dependent on the shaft material as well as the shaft length. This
lag in power
transmission introduces inefficiencies and power loss into the drive train.
Therefore, the
elimination of the third shaft by use of a planetary reduction drive provides
a further
significant advantage of reducing total wind-up in the system.
[0059] The elimination of the third shaft, along with elimination of many
associated
parts, results in a significant weight reduction in the drive train. FIGURE 11
is an exploded
perspective view of the parts of the conventional prior art drive system of
FIGURE 10 that
may be eliminated by one embodiment of the present invention, specifically the
embodiment
shown in FIGURE 13. The reference numbers shown in FIGURE 11 are listed in the
below
table, with associated part numbers, quantity that can be eliminated by the
FIGURE 13
embodiment of the present invention, part description and weight in pounds.
REF # PART NO. QTY DESCRIPTION WEIGHT
IN FIG.
11
201 0702-375 1 DROPCASE W/ STUDS 3.974
202 8011-143 1 BOLT, CARRIAGE 0.038
203 8040-426 10 NUT, LOCK 0.112
204 8011-139 2 BOLT CARRIAGE 0.110
205 0123-523 4 BOLT, RIBBED 0.011
206 0607-025 9 O-RING STUD 0.010
207 0623-117 2 BOLT, RIBBED 0.069
208 8050-247 6 WASHER 0.012
209 0623-317 3 STUD 0.138
210 1602-051 1 BEARING, 1 IN .320
211 1670-237 2 SEAL, O-RING 0.004
212 0670-183 1 O-RING, OIL LEVEL STICK 0.001
-11-
CA 02588356 2007-05-11
213 1602-087 1 SPROCKET 39T 2.036
214 1602-101 1 ADJUSTER, CHAIN 0.068
215 0702-324 1 ARM, TIGHTENER-ASSY 0.496
216 1602-041 1 CHAIN, 70P 1.635
217 8050-212 2 WASHER 0.002
218 0602-369 2 BUSHING, TIGHTENER ARM 0.004
219 0702-115 1 ARM, TIGHTENER .310
220 0623-122 2 NUT, LOCK 0.021
221 0702-129 1 ROLLER, TIGHTENER .398
1NC. 22)
222 0602-383 1 BEARING, CHAIN TIGHTENER .215
223 0123-082 2 PIN, COTTER
224 1602-052 1 BEARING, 7/8 IN 0.332
225 0602-198 2 PLATE, FLANGE 0.136
226 8041-426 NUT, LOCK 0.021
227 0623-094 2 WASHER 0.002
228 0602-456 11 SPROCKET, 20T 0.452
229 0602-437 1 SEAL, DROPCASE 0.021
230 0602-989 1 COVER, DROPCASE 1.985
REF PART NO. QTY DESCRIPTION WEIGHT
231 8002-134 6 SCREW, CAP 0.186
232 8053-242 6 WASHER, LOCK - EXTERNAL 0.006
TOOTH
233 0623-293 2 PLUG, DROPCASE 0.096
234 0623-231 2 WASHER, SPRING 0.090
235 0623-465 2 NUT, LOCK 0.082
236 0702-130 1 SPRING ASSEMBLY .090
237 0623-283 1 WASHER 0.008
238 0623-284 1 WASHER 0.008
239 8050-217 2 WASHER 0.008
240 0123-641 2 WASHER, FIBER 0.002
241 1602-152 1 COVER, OIL VENT 0.033
242 0623-081 4 SCREW, SELF-TAPPING 0.008
243 8050-242 1 WASHER 0.008
244 8042-426 1 NUT 0.016
245 0602-462 1 STICK, OIL LEVEL 0.015
246 8002-135 1 SCREW, CAP 0.038
247 8051-242 1 WASHER, LOCK 0.008
248 8011-137 1 BOLT, CARRIAGE 0.038
249 0123-150 1 NUT 0.016
250 0616-964 1 GUARD, DROPCASE .520
251 0602-876 1 ADAPTER, MANUAL ADJUST .102
252 8050-252 AR WASHER 0.008
253 0623-905 1 SEAL, MANUAL ADJUST .008
-12-
CA 02588356 2007-05-11
254 8050-272 1 WASHER 0.008
255 0702-266 1 SHAFT, DRIVEN 5.589
256 1602-099 1 BEARING, 1 IN (W/ LOCK 0.399
COLLAR)
257 0602-892 1 PLATE, FLANGE 0.136
258 8002-130 2 SCREW, CAP 0.044
TOTAL 20.492
LBS.
100601 While the above table is provided for purposes of demonstrating the
advantage of the current invention, it is important to keep in mind that the
exact parts utilized
in the present invention will vary within the scope of the invention and
should not be limited
by this table. Use in the present invention, of one or more of the parts
listed in this table and
shown in FIGURE 11 does not bring a device outside the scope of the present
invention.
[0061] A further embodiment of a drive train according to the principles of
the
present invention is shown in FIGURES 12-15. FIGURE 12 is a perspective view
of an
engine 301 and a drive train 303 according to the principles of the present
invention. The
drive train 303 includes one embodiment of a continuously variable
transmission,
specifically, a primary clutch 305 that is driven by the engine drive shaft
(not shown), a drive
belt 307 and a secondary clutch 308 driven by the drive belt 307. The drive
train 303 further
includes a planetary gear system 300 including drive shaft 310, track shaft
302, sprockets 304
and 306 and secondary clutch 308 arranged along a center axis.
[0062] FIGURE 14 is an exploded view of one embodiment of a planetary gear
system 300 arranged along a center axis. FIGURE 15 is a sectional view of the
planetary gear
system 300.
[0063] It is important to note that a planetary gear system according to the
present
invention may be any gear reduction system that utilizes a plurality of
planetary gears, a sun
gear and a ring gear to realize a rpm reduction. A planetary gear system may
utilize a
stationary ring gear resulting in rotation of the cage holding the planetary
gears.
-13-
CA 02588356 2007-05-11
Alternatively, it is also within the scope of the present invention that the
planetary gear
system utilize a stationary cage resulting in a rotating ring gear.
[0064] A planetary gear system of the present invention including the
embodiment
shown in FIGURE 14 may be utilized either on the same longitudinal axis of the
engine drive
shaft or the longitudinal axis of the secondary clutch. Each of these
locations of a planetary
gear system is disclosed above. The embodiment of a planetary gear system 300
shown in
FIGURES 12-15 may also be utilized in either of these locations. For sake of
brevity, the
placement of the planetary gear system 300 is only shown and described in the
position on
the longitudinal axis of the track shaft. However, the invention certainly
contemplates the
positioning of the planetary gear system 300 on the longitudinal axis of the
engine drive shaft
as would be well understood by one of skill in the art when considered with
the disclosure set
forth above and throughout this specification.
[0065] Turning first to the planetary gear system 300 shown in FIGURES 14 and
15, the input shaft 310 (also referred to as a drive shaft or first shaft) is
coupled to and is
driven by the secondary clutch 308 shown in FIGURE 10. An input shaft is any
shaft capable
of transmitting rotational energy along its length. An input shaft can come in
many different
configurations. One embodiment of an input shaft is input shaft 310. The input
shaft 310 is
integrally part of the sun gear 312. However, the input shaft of this
invention is not required
to be integral with the sun gear. The input shaft 310 includes a larger
diameter section 313
that sealingly fits within a roller bearing 341 in the first housing member
350. The seal
between the input shaft 310 and the first housing member is provided by a
grease seal 315.
The input shaft 310 is rotatably supported by one or more elements. One
example of such
elements is a bearing or bushing. The embodiment shown in the figure shows the
use of
roller bearings, and more specifically, double row ball bearings 341 and 342.
100661 A planetary gear system may include a planetary cage assembly. A
planetary cage assembly is a plurality of planetary gears and a cage or other
member that
-14-
CA 02588356 2007-05-11
supports the plurality of planetary gears. One embodiment of a planetary cage
assembly is
planetary cage assembly 314. Planetary cage assembly 314 includes a cage
including a pair
of planetary gear plates 316 and 318 held together by spacer's 320a-d. The
plates 316 and
318 carry a plurality of shafts 322, 324, 326 and 328 that rotatably support
the planetary
gears 330a-d, respectively. The shafts 322, 324, 326, and 328 may be
integrally secured to
the plates 316 and 318, which in turn serve to maintain the planetary gears
330a-d in spaced
relationship around the sun gear 312. Spacer's 320a-d may retain plates 316
and 318 in
proper spaced relationship.
[0067] The planetary cage assembly 314 includes a weight bearing protrusion
340
and a bearing or bushing positioned around the weight-bearing protrusion 340.
One
embodiment of the bearing is double row ball bearing 342. A weight bearing
protrusion is a
protrusion or other profile that is capable of structurally supporting the
weight of the sun
gear. The weight bearing protrusion 340, along with the double row ball
bearing 342, are
sized to fit within an opening 344 (see FIGURE 15) in the end of the integral
member
comprising the input shaft 310 and sun gear 312. The weight-bearing protrusion
340
therefore supports the weight of the sun gear 312 and input shaft 310.
[0068] A second shaft of a planetary gear system is any member coupled to one
of
the ring gear and planetary cage assembly wherein such member is capable of
acquiring at
least a portion of the rotational energy of the one of the ring gear and
planetary cage
assembly that rotates. A second shaft may be integral with or connected to the
planetary cage
assembly or alternatively integral with or connected to the ring gear. One
embodiment of a
second shaft of a planetary gear system is second shaft 346. Second shaft 346
is connected to
plates 316 and 318 such that rotation of the plates 316 and 318 results in
rotation of the
second shaft 346. In the embodiment shown in FIGURE 14, the second shaft 346
is a male-
type splined member. It is certainly within the scope of this invention to
have a second shaft
-15-
CA 02588356 2007-05-11
having a female fitting or some other structure for connecting to whatever
member the
second shaft is driving.
[0069] Planetary gear system 300 further includes a housing 349, including
first
housing member 350 and a second housing member 352. The housing members 350
and 352
may be held together by suitable screws (not shown).
100701 Double row ball bearing 360 provides bearing support of the planetary
cage
assembly 314 by the second housing member 352.
[0071] A ring gear 354 is mounted in the second housing member 352. The ring
gear 354 engages the planetary gears 330a-d. As different size ring gears may
be desired, the
ring gear 354 may be removed from the second housing member 352 and replaced
with a
ring gear having a different diameter or different size gear teeth. The sun
gear, planetary
gears and the ring gear may be cast of high carbon steel.
[0072] The sun gear 312, planetary cage assembly 314 and ring gear 354 are
contained in housing 349, including first housing member 350 and second
housing member
352. The housing 349 is sealed and contains lubricating oil. The lubricating
oil is anything
that reduces the wear on the sun gear 312, planetary gears 330a-d, and ring
gear 354. In one
embodiment, the oil used in the housing 349 is synthetic gear lube or
alternatively synthetic
transmission fluid.
[0073] In preferred embodiments of the planetary gear system of the invention,
the
gear reduction ratio ranges from about 6:1 to 1:1. This is contrasted with the
conventional
chain and sprocket reduction ratio range of from 1.6:1 to 2:1. The
conventional chain and
sprocket ratio range is limited by the diameter of the sprockets and the
strength of the smaller
drive sprocket.
100741 Now turning to one embodiment placement of the planetary gear system
300
within the drive train 303, we turn our attention to FIGURE 13. FIGURE 13 is a
perspective
view of a portion of the drive train 303 shown in FIGURE 14. FIGURE 13
includes some
-16-
CA 02588356 2007-05-11
additional components not shown in FIGURE 14, such as the right chassis 362,
left chassis
368, and stiffener 351. In the embodiment shown in FIGURE 13, the planetary
gear system
300 is mounted coaxial with the track shaft 302. The input 310 is driven
through keyed
connection, by the secondary clutch 308 of a continuously variable
transmission. The second
or output shaft 346 of the planetary gear system 300 is coupled to and drives
the track shaft
302. It is certainly within the scope of this invention for the track shaft
302 and second shaft
346 to be an integral or one-piece member.
[0075] In the embodiment of the drive train of the present invention shown in
FIGURE 13, the planetary gear system 300 is positioned adjacent to the outside
of left
chassis 362. It may be desirable to attach the housing 349 to the left chassis
362 with bolts
(not shown) through holes in the left chassis 362 such as holes 363a-e. The
planetary gear
system 300 is supported by a stiffener or bracket 351 that has one end
attached to the housing
349 of the planetary gear system 300 as shown, and the opposite end (not
shown) secured to
an engine mount (not shown).
[0076] The drive train of the present invention includes a track drive
sprocket,
alternatively referred to as a drive sprocket or simply as a sprocket. A
sprocket is any
member attached to a track shaft and engaged with a continuous drive track
such that rotation
of the track shaft causes rotation of the sprocket that causes rotation of the
continuous drive
track. The sprockets 304 and 306 are one well-known embodiment of a sprocket.
[0077] A conventional brake caliper 364 and disk 366 are mounted on the track
shaft 302 to the outside of the right chassis 368. Alternatively, the brake
caliper and disk may
be located to the inside of the right chassis 368.
[0078] A bracket 370 containing a ring bearing (not shown) is secured to the
right
chassis 368 and further supports the track shaft 302.
[0079] A continuously variable transmission is any mechanism or system that
provides variable gear reduction. One embodiment of a continuously variable
transmission is
-17-
CA 02588356 2007-05-11
referred to as a reduced rpm clutch or alternatively a clutch system. One
embodiment of a
continuously variable transmission or clutch system is a primary clutch
(alternatively referred
to as a drive clutch), a belt and a secondary clutch (alternatively referred
to as a driven
clutch), wherein the secondary clutch is driven by and connected to the
primary clutch
through the belt. This type of continuously variable transmission is well
known.
[0080] One embodiment of the present invention utilizes a secondary clutch
that
has a smaller diameter than the prior art secondary clutch. Conventional
secondary clutches
typically have a diameter of about 10.5 to 11.7 inches. One embodiment of the
present
invention utilizes a secondary clutch having a diameter between 8 inches and
9.5 inches. The
embodiment of the secondary clutch shown in FIGURES 12 and 13, namely
secondary clutch
308 has a diameter of 8.6 inches. This diameter is measured from the outer
edge of sheaves
309 and 311.
10081] Significant advantages result from the use of a smaller diameter
secondary
clutch. For example, the smaller diameter secondary clutch results in less
overall mass as
well as less rotating mass. Furthermore, the smaller secondary clutch is more
compact.
Furthermore, as is discussed in more detail below, the smaller secondary
clutch allows for a
wider range of rpm reduction ratios.
100821 The advantage of a more compact secondary clutch such as secondary
clutch
308 is now further described. The present invention may result in placement of
the secondary
clutch on the same axis as the track shaft. A consequence of this placement is
that a larger
diameter or conventional secondary clutch is likely to strike the ground or
snow in certain
snowmobile driving circumstances. Therefore, a smaller diameter secondary
clutch has the
advantage of being able to place such clutch on the axis of the track shaft
and yet maintain
proper ground clearance. The only alternative to the smaller diameter
secondary clutch would
be to raise the track shaft. However, a lower track shaft translates into a
desirable lower
center of gravity for the snowmobile. It may also be desirable to configure
the continuous
-18-
CA 02588356 2007-05-11
track in a particular path that requires the track shaft and sprockets to be
positioned in a
lower position.
[0083] As mentioned above, a further advantage of the smaller diameter
secondary
clutch is the resulting wider range of rpm reduction ratios. The 8.6 inch
diameter secondary
clutch with a standard 8 inch diameter primary clutch yields a start-up ratio
(when the
snowmobile is going from being stationary to moving) of 2.77:1. The full ratio
(when the
snowmobile is moving) is 2.04:1. This yields an overall ratio of the
continuously variable
transmission of 5.65:1. A conventional continuously variable transmission with
the larger
10.5 inch diameter secondary clutch and an 8 inch diameter primary clutch
yields a start-up
ratio of 3.44:1 and a full ratio of between 1:1 and 1.21:1. Therefore, at
best, the conventional
overall ratio of the continuously variable transmission is 4.16:1. This ratio
change from
4.16:1 to 5.65:1 is a 36% increase in ratio range. The 36% increase in ratio
range results in a
better ability for the snowmobile to take-off from starting position to a
moving position with
reduced jerkiness that is caused by the initial engagement of the
transmission.
100841 The operation of the embodiment drive train partially shown in
FIGURES 12-15, including the continuously variable transmission is here
provided. The
engine 301 may be a conventional gasoline powered engine of the type generally
found in
snowmobiles. However, the engine may be any other type of engine suitable for
driving a
snowmobile. The engine drive shaft (not shown in FIGURE 12, but for example a
shaft such
as shaft 15 in FIGURES 2 and 3) rotatably drives the primary clutch 305 that
in turn drives
the belt 307. The drive belt drives the secondary clutch 308 that rotatably
drives the input
shaft 310. The sun gear 312 is then driven by the input shaft 310. The sun
gear 312 engages
the planetary gears 330a-d, which are rotatably supported, in the plates 316,
318. The force
of the sun gear 312 acting on the planetary gears 330a-d cause the gears 330a-
d to rotate and
move along the ring gear 354 thereby rotating the plates 316, 318. The
rotation of plates 316,
318 rotatably drives the second shaft 346. The second shaft 346 rotates at a
rpm lower than
-19-
CA 02588356 2007-05-11
the rotation of the input shaft 310 resulting in a gear reduction. The second
shaft 346 in turn
drives sprockets 304 and 306 that in turn engage and drive the endless track
(such as endless
or continuous track 14 of FIGURE 1).
[0085] The present invention may also include a forward/reverse planetary
unit, as
shown in FIGURES 16-18, for driving the snowmobile in the forward and reverse
directions.
Such a forward/reverse unit could be used in conjunction with any of the
embodiments
described above.
[0086] A forward/reverse planetary unit is a planetary drive system that
includes
the ability to operate in a reverse mode in which the second shaft of the
planetary drive
system rotates in an opposite direction from the input shaft. FIGURES 16 and
17 are
sectional views of one embodiment forward/reverse planetary unit 400. FIGURE
16
illustrates forward/reverse planetary unit 400 in forward mode in which the
second shaft 404
rotates in the same direction as the input shaft 402. FIGURE 17 illustrates
the
forward/reverse planetary unit 400 in reverse mode in which the second shaft
404 rotates in
the opposite direction of the input shaft 402.
[0087] First a discussion of the components of the forward/reverse planetary
unit
400 will be described. Then a discussion of the forward and reverse modes will
be provided
in conjunction with FIGURES 16 and 17 respectively.
[0088] A forward/reverse planetary unit includes an input shaft that is driven
either
directly or indirectly by the engine drive shaft. An input shaft may be
integral or separate, but
connected to, whatever drives it. For example, an input shaft may be integral
with the engine
drive shaft, or it may be a separate shaft. Furthermore, an input shaft could
be integral with a
secondary clutch of a continuously variable transmission. Alternatively, an
input shaft could
be integral with the output of an offset (offset is discussed below). What is
meant by
"integral" is that the two parts that are integral are in actuality only one
piece or one member.
Forward/reverse planetary unit 400 includes input shaft 402.
-20-
CA 02588356 2007-05-11
[0089] A forward/reverse planetary unit also includes an output shaft. An
output
shaft either directly or indirectly drives the endless drive track of a
snowmobile. An output
shaft may be integral or separate, but connected to, whatever it drives. For
example, an
output shaft may be integral with a component of a continuously variable
transmission in the
situation in which the forward/reverse planetary unit is on the front end
(drives the
continuously variable transmission). Furthermore, an output shaft may be, but
is not required
to be, integral with the track shaft. Forward/reverse planetary unit 400
includes output shaft
404.
[0090] An output shaft may, but is not required to, include a weight bearing
protrusion. In the embodiment shown in FIGURES 16 and 17, the output shaft 404
includes a
weight bearing protrusion 405.
[0091] Input shaft 402 includes a first sun gear 406 and a second sun gear
408.
Many different configurations and shapes and designs of sun gears may be used
in this
invention. First and second sun gears 406 and 408 are merely one embodiment.
[0092] A forward/reverse planetary unit includes a first planetary assembly
and a
second planetary assembly. A planetary assembly includes a plurality of
planetary gears and
a cage to support the plurality of planetary gears.
[00931 Forward/reverse planetary unit 400 includes first planetary assembly
410
that includes four planetary gears 412 (only two shown in cross-sectional
views), and cage
414. In this embodiment, cage 414 includes drum 416. Forward/reverse planetary
unit 400
also includes second planetary assembly 420 that includes four planetary gears
422 (only two
shown in cross-sectional views), and cage 424. In this embodiment, cage 424 is
integral with
ring gear 426. Cage 424 is connected to the output shaft 404 so that rotation
of the cage 424
results in rotation of the output shaft 404. Ring gear 426 meshes with the
gear teeth on the
planetary gears 412.
-21-
CA 02588356 2007-05-11
[0094] Forward/reverse planetary unit 400 also includes a second ring gear 430
that
meshes with the gear teeth on planetary gears 422. In the embodiments shown in
FIGURES 16 and 17, second ring gear 430 is supported by a guide 431 in the
housing 452.
[0095] A forward/reverse planetary unit includes a first locking device and a
second
locking device. The definition of a locking device for purposes of this
invention is any device
or mechanism capable of releasably engaging either a cage or a ring gear to
releasably
prevent the cage or ring gear from rotating. A locking device may be a band or
it may be
some other mechanism. For example, a locking device may be an electric magnet
that can be
turned on and off to create a magnetic field capable of preventing rotational
movement of a
cage or ring gear.
[0096] The forward/reverse planetary unit 400 includes a first locking device
that is
first band 440, and a second locking device that is second band 442. First and
second bands
may be conventional reverse lock-up bands used in the automobile industry.
First and second
bands may be made of a steel band with a friction material along the surface
that contacts the
braked member.
[0097] A means for actuating the first and second locking devices may be
provided.
Means for actuating the first and second bands 440 and 442 may include
electric solenoids,
mechanical means including levers, and hydraulic systems. Means 444 and 446
are shown in
FIGURES 16 and 17, with means 444 positioned to actuate first band 440, and
means 446
positioned to actuate second band 442. The means 444 and 446 may result in
movement of
plungers 448 and 450 respectively wherein the plungers interact with the first
and second
bands 440 and 442 respectively. In the embodiment shown in FIGURES 16 and 17,
forward/reverse planetary unit 400 includes a housing 452 through which the
plungers 448
and 450 extend. Housing 452 may be sealed and contain lubricating oil such as
discussed
above with earlier embodiments.
-22-
CA 02588356 2007-05-11
[0098] Elements may be used to support the input shaft 402 and second shaft
404
while still allowing the supported elements to rotate. For example, these
elements may be
bearings or bushings. In the embodiment shown in FIGURES 16 and 17, these
elements are
double row bearings 460, 464 and 468.
[0099] A discussion of the forward/reverse planetary unit 400 in forward mode
is
now provided in conjunction with FIGURE 16. In forward mode, second ring gear
430 is
prevented from any substantial rotation. This is accomplished by actuating
second band 442
to apply it to second ring gear 430. Furthermore, first band 440 is not
actuated or applied to
drum 416. The result is that planetary gears 422 "walk" along stationary
second ring gear
430. Therefore, cage 424 rotates in the same direction as input shaft 402, and
hence second
shaft 404 also rotates in the same direction as input shaft 402.
[00100] A discussion of the forward/reverse planetary unit 400 in reverse mode
is
now provided in conjunction with FIGURE 17. In reverse mode first band 440 is
actuated to
prevent any substantial rotational movement of drum 416 of cage 414. Second
band 442 is
not actuated or applied to second ring gear 430. The result is that planetary
gears 412 drive
ring gear 426 so that it rotates, and ring gear 426 is connected to the second
shaft 404.
Therefore, second shaft 404 rotates in reverse direction to input shaft 402.
[00101] It is noted that the gear reduction ratio of a forward/reverse
planetary unit in
forward mode may be the same or it may be different from the gear reduction
ratio in reverse
mode. The different ratios may be adjusted by adjusting the number of gear
teeth on the first
and second sun gears 406 and 408 as well as appropriate changes to the
planetary and ring
gears.
[00102] Applicant also herein discloses an offset that may be used in
conjunction
with either a planetary gear system or with a forward/reverse planetary unit
within a
snowmobile. An offset is a mechanism that transfers drive power from one axis
to another.
An offset includes a first offset member and a second offset member. The first
offset member
-23-
CA 02588356 2007-05-11
and the second offset member both are capable of rotating in non-coaxial
positions. An offset
may include, but is not required to include, a gear reduction ratio. That is,
the first and
second offset members may rotate at the same rotational speed or at different
rotational
speeds.
[00103] First offset member includes gear teeth that are collectively referred
to as
first offset gear. Likewise, second offset member includes gear teeth
collectively referred to
as second offset gear. A first offset gear is any form of gear capable of
driving another gear.
A second offset gear is a gear capable of being driven by a first offset gear.
The second offset
member may be driven by direct contact between the first offset gear and the
second offset
gear. Alternatively, there may be an intermediate member or members such as a
third
member (not shown) including a third gear between the first and second offset
members.
[00104] FIGURE 18 is a sectional view of one embodiment of an offset combined
with a forward/reverse unit, namely offset and forward/reverse planetary unit
500 (referred to
hereinafter as unit 500). Unit 500 includes first offset member 502 and second
offset member
504. First offset member 502 includes a shaft 506 with a first offset gear
508.
[00105] Elements may be used to support the first offset member while still
allowing
the first offset member to rotate. For example, these elements may be bearings
or bushings.
In one embodiment, the first offset member 506 is rotationally supported by
double row
bearing 510, and single row bearing 514.
1001061 Second offset member 504 includes second offset gear 520 that meshes
with
first offset gear 508 of the first offset member 502. Second offset member 504
is rotatably
supported by one or more elements. For example, these elements may be bearings
or
bushings. In one embodiment, the element supporting second offset member 504
may be
single row bearing 522.
[00107] Second offset member 504 is integral with input shaft 602 of
forward/reverse planetary unit 600. Note that forward/reverse planetary unit
600 is only
-24-
CA 02588356 2007-05-11
shown in the Figures in reverse mode. However, forward mode is also possible
and is easily
surmised from a review of FIGURE 16.
[001081 Input shaft 602 includes a first sun gear 606 and a second sun gear
608.
Many different configurations and shapes and designs of sun gears may be used
in this
invention. First and second sun gears 606 and 608 are merely one embodiment.
[00109] A forward/reverse planetary unit includes a first planetary assembly
and a
second planetary assembly. A planetary assembly includes a plurality of
planetary gears and
a cage to support the plurality of planetary gears.
[00110] Forward/reverse planetary unit 600 includes first planetary assembly
610
that includes four planetary gears 612 (only two shown in cross sectional
views), and cage
614. In this embodiment, cage 614 includes drum 616. Note that a cage, by
definition is not
required to include a drum. Rather, a cage with a drum is merely one
embodiment of a cage.
Forward/reverse planetary unit 600 also includes second planetary assembly 620
that
includes four planetary gears 622 (only two shown in cross-sectional views),
and cage 624.
In this embodiment, cage 624 is integral with ring gear 626. Cage 624 is
connected to the
output shaft 604 so that rotation of the cage 624 results in rotation of the
output shaft 604.
Ring gear 626 meshes with the gear teeth on the planetary gears 612.
[00111] Forward/reverse planetary unit 600 also includes a second ring gear
630 that
meshes with the gear teeth on planetary gears 622. In the embodiment shown in
FIGURE 18,
second ring gear 630 is supported by guide 631 in housing 652.
[00112] A forward/reverse planetary unit includes a first locking device and a
second
locking device. The definition of a locking device for purposes of this
invention is any
mechanism capable of releasably engaging either a cage or a ring gear to
releasably prevent
the cage or ring gear from rotating.
- 25 -
CA 02588356 2007-05-11
[00113] The forward/reverse planetary unit 600 includes a first locking device
that is
first band 640, and a second locking device that is second band 642. First and
second bands
may be conventional reverse lock-up bands used in the automobile industry.
1001141 A means for actuating the first and second locking devices may be
provided.
Means for actuating the first and second bands 640 and 642 may include
electric solenoids,
mechanical means including levers, and hydraulic systems. Means 644 and 646
are shown in
FIGURE 18 with means 644 positioned to actuate first band 640, and means 646
positioned
to actuate second band 642. The means 644 and 646 may result in movement of
plungers 648
and 650 respectively wherein the plungers interact with the first and second
bands 640 and
642 respectively. In the embodiment shown in FIGURE 18, unit 500 includes a
housing 652
through which the plungers 648 and 650 extend. Housing 652 may be sealed and
contain
lubricating oil as discussed above with earlier embodiments.
1001151 Elements may be used to support the second shaft 604 while still
allowing
the second shaft 604 to rotate. For example, these elements may be bearings or
bushings. In
one embodiment, these elements are double row bearings 652 and 654.
[00116] The unit 500 may be utilized in the drive train of a snowmobile in
such a
way that the first offset member is connected to the secondary clutch of a
continuously
variable transmission, which in turn is driven by an engine drive shaft. For
example, one
could replace reduction drive 19 in FIGURE 3 with unit 500 of FIGURE 18. In
such a case
the first offset member 506 would be connected to, or integral with, the
secondary clutch and
the second shaft 604 would be connected to, or integral with, the track shaft.
The secondary
clutch would drive the first offset member 506 and the second shaft 604 would
drive the
endless drive track of the snowmobile.
1001171 An offset combined with a planetary gear system is also disclosed
here. One
embodiment offset and planetary gear system is shown in sectional view in
FIGURE 19.
Specifically, offset and planetary gear system 700 (hereinafter referred to as
unit 700) is
-26-
CA 02588356 2007-05-11
provided. Unit 700 includes a first offset member 702 and a second offset
member 704. First
offset gear 706 of first offset member meshes with second offset gear 708 of
second offset
member 704 so that rotation of first offset member causes rotation of second
offset member.
As with the offset discussed above in relation to FIGURE 18, there may be, but
does not
have to be, a gear reduction ratio between the first offset member and the
second offset
member.
[00118] Elements may be used to support the first offset member while still
allowing
the first offset member to rotate. For example, these elements may be bearings
or bushings.
In the embodiment of FIGURE 19, first offset member 702 is rotationally
supported by
double row bearing 710 and single row bearing 714.
[00119] Second offset member 704 is integral with input shaft 720 of planetary
gear
system 722 so that rotation of second offset member 704 results in rotation of
input shaft
720. Input shaft 720 includes sun gear 724 that drives planetary gears 726 by
being meshed
with such.
[00120] Cage 730 is fixedly secured to housing 732 by clip 734 so that cage
730
cannot rotate relative to housing 732. Ring gear 740 is integral with second
shaft 742 so that
rotation of ring gear 740 causes rotation of second shaft 742. Ring gear 740
is driven by
planetary gears 726 by being meshed with such.
[00121] Unit 700 would be utilized in the drive train of a snowmobile in the
same
location as unit 19 in FIGURES 2 and 3. That is, offset member 702 is driven
by the
secondary clutch of a continuously variable transmission that is driven by an
engine drive
shaft. Output shaft 742 drives an endless drive track, through for example a
track shaft.
Output shaft 742 may be integral with the track shaft.
[00122] Referring to FIGURE 20, in an alternative embodiment, a
forward/reverse
planetary unit 800 has a coupler assembly 802 and a brake assembly 804
selectively engaged
-27-
CA 02588356 2007-05-11
with a planetary gear assembly 806 to cause an output shaft of the planetary
unit 800 to rotate
in forward and reverse directions relative to an input.
[00123] The brake assembly 804 includes a cylindrical slider 808 having an
inner
braking surface 810 and outer braking surfaces 812. The outer braking surface
812 engages a
housing (not shown) surrounding the cylindrical slider 808 such that the
slider is restrained
from rotating about an axis 814 but it translatable along the axis 814. The
inner braking
surface 810 is selectively shifted into engagement with the planetary gear
assembly 806 as
the housing 808 is shifted along the axis 814. In the illustrated embodiments,
the inner
breaking surface 810 and outer braking surface 812 are each embodied as
toothed portions
formed monolithically with the cylindrical slider 808.
1001241 The coupler assembly 802 mounts within a race formed in the
cylindrical
slider 808, such that the coupler assembly 802 is free to rotate relative to
the cylindrical
slider about the axis 814 but restrained from translational movement along the
axis 814. The
coupler assembly 802 is constrained to shift with the cylindrical slider 808
along the axis 814
to selectively engage the coupler assembly 802 with the planetary gear
assembly 806.
1001251 The cylindrical slider 808 may engage a shift lever (not shown) in
order to
enable an operator to shift the cylindrical slider 808 along the axis 814. In
the illustrated
embodiment, hooks 816 mount to the cylindrical slider 808 to engage a shifting
mechanism.
[00126] Referring to FIGURE 21, the planetary gear assembly 806 includes a
cage
818 bearing one or more planetary gears 820 mounted equidistant from an axis
of rotation of
the cage 818. First and second cage gears 822a, 822b engage the cage 818 and
rotate
synchronously therewith. The first and second cage gears 822a, 822b couple to
the cage 818
either by means of a gear interface, a fastening means, or monolithic
construction with the
cage 818. In the illustrated embodiment, the first cage gear 822a fastens to
shafts 824 bearing
the planetary gears 820 or to arms formed on the cage 818. The second cage
gear 822b
includes an aperture 826 having a toothed inner surface that engages a splined
shaft 828
-28-
CA 02588356 2007-05-11
fixedly secured to the cage 818. A ring gear 830 engages the planetary gears
820 and
includes an inner toothed surface 832a meshing with the planetary gears 820
and an outer
toothed surface 832b selectively engaged with the coupler assembly 802 and the
brake
assembly 804.
[00127] In the illustrated embodiment, thrust washers 834 positioned on either
side
of a thrust bearing 836 are interposed between the cage and the ring gear 830
to reduce
friction in instances where the ring gear 830 rotates relative to the cage
818. A thrust bearing
836 may also be positioned between the ring gear 830 and the second cage gear
822b. In the
illustrated embodiment, a snap ring 838 engaging the splined shaft 828
prevents removal of
the second cage gear 822b from the splined shaft 828. A thrust bearing 836,
thrust washer
834, and collar 840 may be interposed between the snap ring 838 and the second
cage gear
822b.
[00128] Referring to FIGURE 22, the planetary gear assembly 806 further
includes a
sun gear 842 engaging the planetary gears 820. The sun gear 842 is typically
driven by an
input to the planetary unit 800. In the illustrated embodiment, the sun gear
842 is mounted on
a shaft 844 with an input gear 846 secured thereto. The shaft 844 further
includes a weight
bearing protrusion 848 for supporting the shaft 844 when the shaft 844 is
installed within the
planetary gear assembly 806.
[00129] Referring to FIGURE 23, the coupler assembly 802 includes a ring gear
850
having an inner toothed surface 852 selectively engaged with the planetary
gear assembly
806. A splined output shaft 854 mounts to a coupler hub 856. The coupler hub
856 engages
the ring gear 850 such that the coupler hub 856 is constrained to rotate with
the ring gear 850
but the ring gear 850 is translatable along the axis 814 relative to the
coupler hub 856. In the
illustrated embodiment, the coupler hub includes projections 858 extending
outwardly from
the output shaft 854. The projections 858 bear teeth 860 extending along the
axis 814. The
teeth 860 engage grooves 862, or teeth 862, secured to the inner surface of
the ring gear 850.
-29-
CA 02588356 2007-05-11
[00130] A detent mechanism 864 is used to bias the coupler assembly 802 and
brake
assembly 804 toward forward and reverse positions. In the illustrated
embodiment, the detent
mechanism 860 includes pawls 866 having a first end 868 inserted within
apertures 870
formed in the projections 858. Springs 872 urge the pawls 866 outwardly from
the apertures
870. Washers 874 may be interposed between the springs 872 and pawls 866.
Second ends
876 of the pawls 866 project into a groove 878 formed in the ring gear. The
groove 878 may
extend around the inner circumference of the ring gear 850. Alternatively,
smaller individual
grooves or depressions may be formed near the teeth 862.
[00131] Referring to FIGURE 24, a roller bearing 880 is positioned over the
output
shaft 854 and engages a housing or vehicle frame to support the output shaft
854. A roller
bearing 882 may be positioned within an aperture 884 formed in the coupler hub
856, or
output shaft 854, to receive the weight bearing protrusion 848 formed on the
shaft 844 of the
planetary gear assembly 806.
[00132] Referring to FIGURE 25A, in some embodiments, a drive gear 886 secures
to an input shaft 888 offset from the output shaft 854. The drive gear 886
drives the input
gear 846 of the planetary gear assembly 806, causing the input gear 846 and
sun gear 842 to
rotate in a direction opposite the input shaft 888.
[00133] In the forward configuration, the inner braking surface 810 of the
braking
assembly 804 engages the first cage gear 822a. The ring gear 850 of the
coupler assembly
802 meshes with the outer toothed surface 832b of the ring gear 830. The inner
braking
surface 810 restrains the cage 818 from rotating, whereas the ring gear 830 is
coupled to the
output shaft 854 through the ring gear 850 and hub 856. The sun gear 842
rotates the
planetary gears 820. However, because the cage 818 is constrained, the
planetary gears 820
cause the ring gear 830 and thus the output shaft 854 to rotate in a direction
opposite the sun
gear 842, which is the same direction as the input shaft 888.
-30-
CA 02588356 2007-05-11
[00134] Referring to FIGURE 25B, to shift the planetary unit 800 into reverse,
the
cylindrical slider 808 is shifted to the right of its position in FIGURE 25A.
As the cylindrical
slider 808 is shifted to the right, the coupler assembly 802 is constrained to
move as well. In
some embodiments, the coupler assembly 802 is constrained to move by snap
rings 890
secured to the inner surface of the slider 808. In the illustrated embodiment,
a single snap
ring 890 is used and a shoulder 892 is formed near the inner surface of the
slider 808 to
capture the coupler assembly 802 between the snap ring 890 and shoulder 892.
[00135] In the reverse configuration, the inner braking surface 810 of the
braking
assembly engages the outer toothed surface 832b of the ring gear 830 and
restrains the ring
gear 830 from rotating. The ring gear 850 of the coupler assembly 802 meshes
with the
second cage gear 822b, effectively coupling the output shaft 854 to the second
cage gear
822b.
[00136] In the reverse configuration, the sun gear 842 rotates the planetary
gears
820. Inasmuch as the ring gear 830 is restrained from rotating, the planetary
gears 820 and
therefore the cage 818 to which they are mounted are constrained to move in
the same
direction as the sun gear 842, or opposite the input shaft 888, but at a
reduced speed. The
second cage gear 822b, which is coupled to the output shaft 854 transfers the
rotation of the
cage to the output shaft 854.
1001371 Refer now to FIGURE 25C, while still referring to FIGURES 25A and 25B.
Movement of the coupler assembly 802 causes the second ends 876 of the pawls
866 to rotate
to the right or left. The pawls 866 may include a notch 894 formed in one
side. As the pawl
moves toward a vertical orientation, the first ends 868 of the pawls 866 are
forced into the
apertures 870. As the pawls 866 move away from the vertical orientation,
whether to the
right or the left, the springs 872 force the first ends 868 of the pawls 866
outwardly. In this
manner, the biasing force of the springs 872 must be overcome to move the
cylindrical slider
808 between forward and reverse configurations. In a manual shifting
arrangement, the
-31-
= CA 02588356 2007-05-11
biasing force of the springs 872 further provide tactile feed back to the
operator indicating
that the cylindrical slider 808 has been moved sufficiently to switch between
forward and
reverse directions. In both manual and actuated shifting, the biasing force
promotes the
proper alignment of the gears.
[00138] To put the planetary unit in a neutral configuration, the cylindrical
slider 808
is positioned as shown in FIGURE 25C having both the inner braking surface 810
and the
inner toothed surface 852 of the ring gear 850 disengaged from the planetary
gear assembly
806. In the preferred embodiment, neutral is not a set operating position, but
rather a
transitory state passed through when shifting between forward and reverse
positions.
[00139] While the preferred embodiment of the invention has been illustrated
and
described, as noted above, many changes can be made without departing from the
spirit and
scope of the invention. Accordingly, the scope of the invention is not limited
by the
disclosure of the preferred embodiment. Instead, the invention should be
determined entirely
by reference to the claims that follow.
-32-
