Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a fluid cooled clutch.
This is a division of copending Canadian Patent
Application Serial No~ 400,560, filed April 6, 1982.
Variable pulley transmission assemblies are known
in the prior art and are comprlsed of variable sheave pulleys,
a connecting belt means and a control means. In automotive
applications it has been necessary to utilize hydrodynamic
and/or clutch assemblies as starting devices. This same
automotive application requires a means or method to effect
a change of direction. It has been found that forward-reverse
gear mechanisms having planetary gearing and sepaxate clutches
cvuld perform such a task. Planetary gearing also provides
a means to attain a desirable gear reduction. Alternatively,
a change of direction could be accomplished with a reversal
of the pulley rotation. This method of directional change,
assuming low belt ratio, requires stopping pulley rotation
and initiating motion of ~he drive train members in an oppo~
site direction. Further, a change of belt ratio when the
pulleys are stopped requires that the belt be slid across
the pulley faces causing wear on both the belt and the pulley
surfaces, and requires a great deal of force to perform such
a belt movement.
A var.iable pulley transmission assembly may be
operable between a prime mover and a driven means. The
assembly includes, in order, from the prime mover, a vibration
damper, input and output movable sheave pulleys connected
by a flexible belt~ a belt ratio control arrangement, a wet
clutch, a forward-neutral-reverse gear arrangement and
connecting elements to a drive means, generally a differen~
tial drive system with rin~ and pinion gear set. This
apparatus is adaptable for use with an automobile where the
engine is the prime mover and the final drive means is a
dif:Eerenti.al-axle-wheel assembly.
- 1 -
mab/Jc
~^
87~
According to the present invention there is pro-
vided a fluid cooled clutch including a generally annula.r
laminated clutch disc assembly having an inner and an outer
periphery which disc assembly includes a central d,isc with
opposed surfaces, a resilient material layer af:Eixed to
each surface and a friction material layer affi.xed to each
resilient layer where each resilient layer is at least as
thck as the friction material layer. A pattern of grooves
is provided in the friction material layer, which grooves
extend completely through the friction material layer and
through substantially all of the resilient layer thus pro-
viding a path for coolant fluid :Elow in the laminated struc-
t.ure which is subst,antia',.ly greater than that of a grooved
friction layer.
In a specific embodiment of the invention there is
provided a plurality of channels in the friction material
layer and. resilient material layer of a depth substantially
equal to .the depth of the grooves, which channels extend
from the inner periphery to the outer periphery of the friction
material layer, with each channel tapering from a given
d~mension at the inner periphery to the dimension smaller
than the given dimension at the outer periphery, to transfer
fluid to ~he grooves along the radial extent of the disc
assembly.
The clutch of the invention may be a fluid actuated,
fluid cooled, slippable, speed-responsive, starting clutch
which is mounted on a shaft and is coaxial with the driven
mab/
or ou-tput pulley. A forward-neutral-reverse gear means,
hereafter forward-reverse, may be mounted along the shaft
and a countershaf~. The starting clutch, when engaged,
provides a driving connec~ion between the shaft and the
forward-reverse gear means, so that the belt and the pulleys
of the CVT continuously rotate in the same direction no
matter which direction of drive (forward or reverse) is
selected. A control system may be provided for regulating
the fluid volume in one fluid circuit and pressure in a
second fluid circuit -to thereby effect the sheave gap of
the pulleys, and the operation of the slippable s-tarting
clutch, and the flange load on the belt.
One way of carrying out the invention is described
in détail below with reference to drawings which illustrate
only one specific embodiment~ in which:-
` FIGURE 1 is a diagrammatic view of a variable
pulley transmission system in a drive train at a low drive
or i.dle c.ondition;
FIGU~E 2~ is a detailed illustration of the trans-
mission assembly along the first two axes of the assembly;
FIGURE 2B is a detailed illustration of -the trans-
mission assembly a].ong the last two axes; and
FIGURE 3 is an enlarged showing of the slippable
starting clutch;
mab/~
~ IGURE 4 is a cross-section view of a c3utch
disc assembly;
FIGURE 4A is a cross-section view si.milar to
that o FIGURE 4, but taken on an enlarged scale
to show structural details;
FIGURE 5 is a plan view depicting a s gment
o~ an annular clutch plate with an oil-groove
pattexn; and
FI~URES 6-8 are graphical illustrati~ns
useful in understanding the operation.
In the drawings like numbers refer to like
elements.
: . .. . . . .
.... .
FIGURE 1 is a diagrammatic drawing of an
assembly of a transmission mechanism 10 in a drive
train connected to a prime mover 12, noted as an
engine. The assembly 10 has four horizonta:L and
parallel axes lettered A, B, C and D. The assembly
includes a continuousl~ variable pulley trans-
mission (CVT) 14, connected between axes A and B,
2Q a slippable starting clutch 16 on axis B, a
forwa.rd-reverse gear means 18 on axes B and C, and
a final dri.ve assembly 20 along axis D. A ~rans
mission control means 22 is shown along axis A.
The power train elements in FIGURE 1 distributed
along axis A from the prime mover 12 are a first
shaft 24, coaxial with axis A, on which shaft 24
is. A torsional vibration damper 28 is drivingly
connected to shaft 24r which damper 28 is affixed
to a flywheel 26 connect.ible tc the prime mover
12. Mounted on shaft 24 is an input variable
driver pulley assembly 30 which includes a fixed
sheave 66 and a movable sheave actuator 32, and
the transmission control means 22.
Affixed to and operable with fixed sheave 66
is a sprocket 31. A fluid pump 33, which is
illustrated as offset ~rom the axes ~ through D,
has a shaft 39 on which shaft 39 there is af~ixed
a second sprocket 35 which is drivingly connected
by a linking means 37 to sprocket 31. ~luid pump
. . 33 is continuously driven by shaft 39 during
engine operation to supply fluid at line pressure
through conduit means not shown.
Mounted along axis A, between pulley 30 and
control means 22~ and driven hy shaft 24 is a
lubricating pump 136.
Coaxial with second axis B is a driven shaft
34~ Mounted on the shaf-t 34 is an output variable
driven pulley assembly 36 which includes a movable
sheave actuator 38, cluster driver gears 40 o~ the
forward-reverse gear means 18 and the slippable
starting clutch 16, which is fluid-actuated and
controlled by control means 22. Input pulley 30
and output pulley 36 are connected by a belt means
~2.
Axis C is coaxial with a countershaft 43 on
which are mounted cluster driven gea.rs 44 of the
forward-reverse gear means 18. Driven gears 44 are
in continuous engagement with drivex gears 40 on
shaft 34~ Operative be-tween the forward and
reverse drIven gears 44 and splined on countershaft
43 is a synchronizer 46 which is slidably connected
to a gear shift rail 47 to selectively engage
either the forward or reverse gear of driv~n
gears 44. Splined to and driven by shaft 43 is a
pinion gear 48. A differential assembly 50 of
final drive assembly 20 defines a flange 52 on
which is mounted a ring gear 54. Ring gear 54 is
continuously engaged with pinion gear 48. Mounted
and operative between cluster driver gears 40 and
.... ..
: driven gears 44 is a reverse idler gear 41, as
known in the prior art.
The final drive assembly 20 is coaxially
mounted along axis D and includes a drive axle 56.
Differential assembly 50 is connected to the drive
axle 56 in a manner known in the prior axt.
.
Referring now to FIGURE 2A, a vib.ration
damper 28 is shown mounted on shaft 24 and connected
to flywheel 26 with year teeth 27, and this two
element combination of vibration damper and
flywheel is protectivel~ covered by a housing 58.
Mounted in housing 58 above the teeth 27 of flywheel
26 is a magnetostrictive device 57 of a type ~nown
in the prior art to produce an electronic signal
which is communicated to control means 22 by
z
conductox means 59. This signal is calibratable
through control means 22 as a measure of input
speed. Housing 58 defines a bore 60 Shaft 24
with a bearing asse~bly 64 mounted thereon extends
thxough bore 60 to re~ain bearing 64 therein.
Driver pulley assem~ly 30 is mounted on shaf~ 24
internal to housing 58 and downstream from bearing
~4.
Driver pulley assembly 30 includes a ~ixed
sheave 6~ and a movable sheave 68. ~ixed sheave
66 defines an inner sloped face 70 and~ in co- -
operation with shaft 24 defines a sleeve 72 with a
shoulder 73, a fluid conduit 74 and a passage 76
with ports 78 and 80. Movable sheave 6B defines
an inner sloped face 82, an extended ~rm 84, a
sleeve 86, fluid passage 88 with ports 90,92, an
inner cha~ber face 94, and an inner cha~ber surface
~6 of arm 34. Sleeve 86 and sleeve 72 cooperat~
to deine annular fluid chamber 98, and a ball track
100 wherein bearin~ ball 102 are positioned to
thereby ball-spline sleeve 86 about sleeve 7~. An
annular piston flange 104 with a wall 105 is
formed to define a recess 106, a bore 108 and a
brace wall 110~ The bore 108 and wall 110 axe
~5 slidably pressed onto shaft 24 against shoulder
73. Rece.ss 106 with a shoulder 107 can receive
sleeve 86 and has wall 110 to bear a thrust load.
~lange 104 with a lip seal 103 sealingly contacts
inher chamber surface 96 of arm 84, and surface 96
cooperates with inner chamber face 94 and sleeve
86 to define a fluid volume chamber 114 which
co~municates to fluid conduit 74 through ports
78,80,90 and 92, passages 76 and 88 and fluid
-- 7 --
chamber 98. A flange cap 116 has a wall 118
conforming generally to the shape of piston ~lange
104 without contacting flange 104. Cap 116 is
affixed to arm 84 and is movable with movable
sheave 68. Wall 118 defines a bore 120 that is
slidable along shoulder 107 of recess 106 but does
not bear on shoulder 107~
Wall 118 defines a fluid vent hole 119 to
allow fluid linkage to evacuate during pulley 30 .
rotation from the gap between piston flange 104
and cap flang~ 116.
An annular bearing assembly 122 is pressed on
sleeve 72 against wall 110 and secured in that
. position hy a lock nut 124 affixed to shaft 24,
both bearing 122 and lock nut 124 are kno~n in the
prior art. A housiny 126 defines a bore 128 to
receive and retain bearing assembly 122~ Housing
126 is secured by means 127 known in the art to
housing 58. A tubular insert 130 is positioned in
1uid conduit 74 and extends through bearing 122
and lock nut 124 and has mounted about this extended
portion a ca.p 132 having walls 134 pressed into
bore 128 to abut bearing 122 without disturbing
loc~ nut 124.
A gerotor pump 136 for lubrication only, such
as those manufactured by Nichols Corporation, has
a cover 138 defining a recess 140 to receive the
tubular insert 130. There is a cross-drilled hole
141 defined by cover 138 that allows communication
37~
from an external source to the conduit 74 through
tubular insert 130. The pump 136 .is affixed to
housing 126 by means known in the art. Tubular
insert 130 is held by locking pins 142,144 secured
to sleeve 72 and pump 136, respectively,
Belt means 42 connects dri~er pulley assembly
30 with driven pulley assembly 36 which driven
pulley 36 is mounted on shaft 34 that is coaxial
with axis B. Belt means 42 is known in the prior
art.
Pulley assembl~ 36 has a ~i~ed sheave 150 and
a movable sheave 152 which is movable in an axial
direction along shat 34. Shaft 34 defines a
through-hole fluid conduit 154 extending longi-
. tudinally through shaft 34. This conduit 15.4 has
been reamed at both ends and receives a Eluid
source connectible insert 156 communicable to a
fluid source at one end, and a lubricating insert
- 158,known in the art, and an end-plug 160 at the
opposite end. Shaft 34 deEines lubricating
passage 162 with ports 164,166 and a second
lubricatin~ passage 168 with ports 170,172 which
passages and ports communi.cate with lubrica-ting
insert 15~. Shaft 34 de:Eines shoulders 171 and
173, a fluid passage 174 with ports 176 and 178
and a second fluid passage 180 with ports 182 and
184, in proximity to clutch 16.
Movable sheave 152 includes an exterior
sloped ~ace 186 and an interior wall 187, an
extended rim 188 with a contact surface 190, a
sleeve 192, and a rib 193 pro~ruding froM wall
187. Sleeve 192 defines a fluid passacJe lg4 and
communicating ports 196,198 therewith.. 51eeve lg2
cooperates with shaft 34 to define an annular
fluid chamber 200 which communicates be-t~een
passages 174 and 194; and, sleeve 192 and shaft 34
also cooperate to de~ine a ball track 202 there-
between, in which are positioned bearing balls 204
lD to thereby ball spline movable sheave 152 to shaft
34. A pin ~06 is fitted into shaft 34 extending
into track 202 in proximity wi~h passage 174 to
serve as a positive stop for bearing balls 204~
An annular piston flange 208 with lip seal 20~,
similar to flange 104 of input pulley 30 r is
formed about shaft 34. Flange 2Q8 defines a
.... ..... .. xecess 210, a surface 211, a bore 212 and a wall
! ` 214. Flange ~08 sealingly contacts extended rim
188 along surface 190. FlancJe 208 defines a
shoulder 216, and an orifice 218 of about forty~
five thousandths (0.045~ inch diameter which
ori~ice 218 can have a "Wiggle Wire" inserted
therein to maintain flow but which is not here
shown. Affixed to rim 188 at movable shea~e 152
is a balance flange cap 220 that is formed in a
ashion similar to flange cap 116 at driver
pulley 30. Flange cap 220 defines a ~ore 222
about surface 211 and travels with movable sheave
152 along surface 211 without contactincJ it~
Movable sheave 152 and piston flange 208
cooperate to define annular ~luid chamber 224 that
communicates with fluid conduit 154 through passayes
174,lg4 and chamber 198. A coil bias spring 226
-- 1()
is retained in chal~er 224 against rib 193 of
sheave 152 and shoulder 216 of flange 208. Spring
226 biases movable sheave 152 in the direction of
fixed sheave 150. Flange 208 and flange cap 220
cooperate to define a fluid pressure ~alancing
cavity 228 which communicates with chamber 224
through orifice 21~. Piston flange wall 214 is
secured against shoulder 171 of shaft 34 by a
bearing assembly 230 which is secured in position
on shaft 34 by a lock nut 232 affixed on shaft 34.
Housing 58 defines a bore 234 and shoulder 236 to
seat and retain bearing 230, and also defines a
recess 235 to enclose lock nut 232.
Mounted at the opposite longitudinal end of
.~5. .. shaft 34 from bearing 230 is clutch 16. Mounted
on shaft 34 between clutch 16 and ixed sheave 150
of pulley assembl.y 36 axe the cluster driver gears
40 of forward-reverse gear means lg. Dri~er gears
~0 include a forward gear 238 which defines a
sleeve 240 with lands 242 and 244. Gear 238 is
mounted on and rotatable about shaft 34 and is in
proximit~ to but separated fxom fixed sheave 150
b~ a support 246 deined by housing 126. Support 246
defines bore 248 in which is seated and retained a
bearing assembly 250 mounted on shaft 34 to maintain
support 246 concentric about shaft 34. Abu~ting
shoulder 173 of shaft 34 is an annular stop ring
252 against which is mounted a bearing assembly
254. Sleeve 240 is mounted about a bearing 25
positioned on shaft 34 and abuts bearing 254.
~ 11 --
Shaft 34 defines a fluid entry hole 258 which
communicates to the outer diameter of shaft 34.
Insert 158 defines a passage 260 which can pick up
and communicate a measured volume of fluid. This
insert 158 transports lubricant to bearing 250,
254 from ~earing 256 through passages 162 and 16$,
respectively.
Cluster driver gears 40 have a reverse gear
262 affixed to and rotatin~ with land 242 of
sleeve 240~ Reverse gear 262 defines a shoulder
264 on whic~ is affi~ed a sprag gear 266 for the
parking mode of the transmission assembly 10.
Cluster driver gears 40 can also be a single
assembly. Mounted on land 244 of sleeve 240 is a
retaining bearing 268 which is held in position by
15 ~
a flange 270 defined by housing 126~ which flange
defines a bore 272 to seat beariny 26~ against an
annular stop 271 and a spacer 274. Stop 271 is
secured to flange 270 by means known in the art.
Clutch assembly 16 is shown in FIG. 3 in an
enlarged ~iew and includes a cup-shaped cover
plate 300, a pressure or driven plate 302, a reaction
p]ate 30~, a clutch disc assembly 306, a Belleville
spring 308 and connecting elementsr Clutch 16 is
mounted on shaft 34 where cover plate 300 defines
a hub 310 and a tapered bore 312. Clutch 16 is
fitted onto shaft 34, positioned by a dowel pin
314 and secured at hub 310 by a locknut 316~ which
abuts hub 310 and is screwably affixed to shaft
- 12 -
7~
34. Cover plate 300 defines a front face 318~ a
perimeter wall.320, a series of connecting-means
portals 322 on its fxont face 318, and a plurality
of vent holes 324 equispaced ~n perimeter wall
320. Hub 310 defines a conduit 326 and ports 328,
330. Cover plate 300 and pressure plate 302
cooperate to define an annular clutch fluid
pressure chamber 332 which communicates with
conduit 154 through passage 180 and conduit 326.
Reac~ion plate.304 is affixed to cover plate
300 by a securing means 334 illustrated as a pin
or dowel, this reaction plate 304 has a backface
305. Plate 304 can be secured by any means known
in the art~ Clutch disc assembly 306 includes a
clu~ch disc 336 with large oll grooves for fluid
transfer ~not shown ~ere), an annular ring 342 ana
a spline member 344. Clutch. disc 336 has surfaces
337 and 339 which have resilient layers 341 and 343
(shown in Figs. 4 and 4A) affixed thereto and
2~ friction facings 338 and 340 respectively mounted
thereon. This composite arrangement is p~sitioned
between and engageable by pressure plate 302 and
reaction plate 304. Disc 336 is drivin~ly affixed
to the outer perimeter of annular ring 342 and -this
combination is secured to the spline member 344 at
the inner diameter o~ annular ring 342, which
spline member 344 is splined to sleeve 240 of
forward gear 233.
Clutch 16 is fluid actuated and, according to the
present invention, is cooled. Coolant is provided
through a fluid conduit 346
- 13 -
.
7~
connected to a fluid source (not shown in FIGURE
3). Plate 304, annular ring 3~2 and plate 271
define an open cavity 348.
~,
A thin metal annular sheet 347 affixed to
p~ate 271 is in a plane parallel to face 305 of
driven plate 304 of clutch 16. ~lange 270 and
metal plate 347 define a wide passage 349 which
communicates with conduit 34~. Plate 271 defines
a large port 276 which communicates between passage
349 and cavity 3~8. ~eaction plate 304 defines a
shoulder 350 to retain the cooling fluid in clutch
cavity 348~during rotational motion o~ the clutch.
Clutch disc assembly 306 and pressure plate 302
coop~rate to define an irregularly shaped annular
- 15~ cavity 352 in clutch 16 which cavity 35~ communicates
with vent holës 324 of cover plate 300. Annular
ring 342 defines a series of communicating po.rts
354 to.communicate coolant fluld from cavity 348
to cavit.y 352 and thereafter past both faces of
clutch plate-336 and thus to provide coolant fluid
emission through vent holes 3~4 during rotation of
the clutch 16.
Pressure plate 302 is connected to zero rate
(as explained in U. S. Patent No. 3,951,393~
Bellevill~ spring 30B by connecting means 356
through portals 322, and plate 302 is biased by
spring 30B to a disengaged condition as illustrated
in ~IG. 3. Pressure.plate 302 is fluid actuated
by fluid pressure in chamber 332 ade~ua-te to
- 14 -
overcome the force of Bellcville spring 308 and to
thrust pressure plate 302 in an axial di.rection
- into contact with clutch disc assembly 306 and,
therethrough, into driving communication with
S reaction plate 304 through friction faces 338,
340 r
Mounted in proximity to vent holes 324 is a
magnetostrictive device 358, although any similar
transducer signal generator would do, that monitors
a magnet.ic field effec-t change inauced by the
change in plate mass as each vent hole 324 passes
- it. This device 358 is known in the prior art and
produces a signal that can be calibrated through
control means 22 to indicate pulley 36 output
Speed,
. .
Referring to ~IG. 2B driven gear means 44 of
forward-reverse gear means 18 of FIG~ 1 includes a
forward gear 384 and a reverse gear 390, with
bearing means on countershaft 43 which is coaxial
with axis C. ~lange 270 defines a bore 362 -for
seating a bearing assembly 364 which is secured in
p~sition by a snap .ring 366 set in an undercut in
flange 270. A thrust plate 368 is mounted on
countershaft 43 on the opposite side of bearing
assembly 364 from snap ring 36~ and these elements
are .reta.ined on the end of sha:Et 43 a~ainst driven
gear5 D~ ~ .
Countershaft 43 defines a thrust shoulder
370, land 372, spline 374 and land 376 each shown
with a smaller cross-section on shaft 43 than the
- 15
. - \~
previously mentioned cross~section. A toothed
ring 375 is splined to shaft 43 at spline 374 and
synchronizer 46 is slidably mounte~ thereon.
Shaft 43 also defines a blind-drilled lubricating
condui-t 378 along its longitudinal axis an~, fluid
lubricating passages 380 and 382 which communicate
~etween conduit 378 and lands 372 and 376, res-
pectively, at the surface of shaft 43. Lubricating
fluid can be communicated to conduit 378 through a
conduit means 379 mounted in the en~ of conduit
378 and connectible to lubricating pump 136, shown
in ~IGo 2A~ Journalled on land 372 of shaft 43
and abuttin~ shoulder 370 is forward gear 384 of
driven gears 44. This forward gear is freely
rotatable about countershaft 43 and is in continuous
engagement with driver forward gear 238 on shaft
-- 34. Pressed on land 376 of shaft 43 is a bearing
assembly 388 on which is mounted r~verse gear 390
o driven gear means 44. This gear 390 is freely
rotatable about countersha-Et 43 and continuously
engaged with reverse idler gear 41 of FIG. 1 of
gear means 40 as known in the art. Slidably
mounted on toothed ring 375 is synchronizer 46
that defines an annular groove and which synchronizer
25 46 is slidably engageable with either forward gear
384 or reverse gear 390. Synchronizer 46 also has
a neutral position between these forward and
reverse gears 384, 390 and is slidable by a gear
seleetion fork 392 positioned in ~roove 394 defined
by synchronizer 46. Synchronizer 46, at engagement
with either forward 384 or reverse 390 gears -transfers
- 16 -
power thro~lgh countershaft 43 to ring gear 54 mounted
on the differential assembly 50 Qf the final drive
assembly 20. Power is transferred to an axle or
wheel arrangement as known in ~he prior ark and as
illustrated in FIG. 1.
FIGS. 4 and 4A illustrate a part of the
laminated clutch disc assem~ly 306 where the
clutch disc 336 is a single narrow annular plate.
Disc 336 has opposed surfaces 337 and 339. Affixed
to each of these surfaces 337,339 is a resilient
material îayer, 341 and 343, respectively, such as
Armstrong Cork Company~ 5 NC-711 material, which is
a cork and neoprene composition. Mounted on ana
affixed to each of these energy-absorbing material
layers 341 and 343 is a friction facing material
- - layer 338 and 340, respectively. This laminated
clutch structure is generally very narrow in
width, that is, on the order of 0.180 to 0 192
inch noted as dimension "x". Each of these resilien~
layers 341,343 is at least as thick as the thickness
of the friction layexs 338 and 340, and preferably
twice as thick as the friction layers.
FIG~ 5 illustrates a segment of an engaginy
face of the friction facing material 33B or 340 on
the clutch disc assembly. As shown, a pattern of
oil grooves 345 is deEine~ on the friction facin~
layers. The result appears as a waffle pattern,
that }s, equal surface areas, genPrally rectangular
islands 353 of at least one-twenty fifth square
inch in surface area. Clutch disc assembly 306
laminated structure has an inner periphery 355 and
- 17 -
7~
an outer periphexy 357 ana the friction material
layers are disposed between these peripheries
Islands 353 are clustered in groups which appear
as arcuate seyments~ These arcuate segements
define tapered channels 351 therebetween.
Each channel 351 has a given dimension at
inner periphery 355, and the channel tapers,
becoming gradually narrower as it extenas to
outer periphery 357. At the outer periphery~ the
channel width is reduced to a very small dirnension,
of the order of one to three hundredths of an inch
in the illustra~ed e~bodiment~ F.l.uid communication
ports 354 are proviaed in clutch disc 306 providing
a passage for cooling oil to inner periphery 355
of the friction material layer. From this location
.. the cooling oil enters the throats of channels
351, which in turn communicate with grooves 345 of
friction surface layers 338 and 340. Channels 351
appear as discontinuities in the otherwise continuous
cross-hatched or waffle pattern ~n these friction
surfaces.
In accordance with an important aspect of the
invention, the depth of grooves 345 is at least
twice the thicXness of friction layer 338 or 340.
This added depth provides a much greater volumetric
flow ~or cooling fluid than is otherwise possible,
with a consequent increase in cooling effectiveness.
To provide the requisite volumetric flow, grooves
345 extend into the resilient material layer~ If
the resilient material layer is as thick as the
friction material layer, the grooves extend -~hrough
substantially all of the resilien~ layer.
- 18 -
In a preferred embodiment, the resilient layers
are substantially twice as thick as each of the
friction material layers. In this case the grooves
345 extend completely through the fric-tion material
layer (338 or 340~ and through substantially one-
half the resilient layer (341 or 343~. The ooolant
fluîd ~low can be waste fluid from the high
pressure control line diverted through the clutch
coolant conduit 346 before its return to a sump.,
This large volume of waste oil is transferred
through the extra deep grooves of the clutch
friction facing and resilient layers, to provide
much more effective cooling than is accomplished
with conventional clutch structures. The coolant
is transferred to conduit 346 through a large,
, about three-quarters of an inch deepl ditch at
' less than one PSI pressure.
Transmission mechanism 10 is responsive to a
,control system 22 signal. The mechanism 10 provides
a slippable starting clutch 16 that is fluid
cooled and fluid pxessure actuated. The variable
pulley system 14 of mechanism 10 is likewise fluid
operated. At prime mover 12 start-up~ the con-
tinuously variable pulley transmission (CVT~ 14 is
as shown in the upper halves of pulley5 30 and 36
in FIG. 2, that is, where the belt 42 is at its
bottom travel or low belt ratio in the driver
pulley assembly 14 and the engine flywheel 26 is
affixed to prime mover 12 as in FIG. 1. ~otational
velocity is transmitted to driver pulley assembly
-- 19 --
7~
30 by shaft 24 and thereafter throuyh belt 42 to
- driven pulley assembly 36. Driven pulley assembly
36 continuously drives shaft 34, which is affixed
to fixed pulley sheave 150, and to clutch cover
plate 300 at the hub 310 with locknut 3167
Clutch 16 engagement proviaes a driving
connection to synchronized forward-reverse di-
rectional gear means 18 from pulley system 14.
The use of gear means 18 obviates the necessity to
change belt direc~ion~to provide a change of
direction to the final drive assembly 20.
Driving power from clutch 16 is provided to
the driver gears 40 of forward-reverse gear means
18 through sleeve 240 which is mounted on and
rotatable about shaft 34. Forward gear 238 is
a~fixed to sleeve 240 and is con-ti.nuously engaged
to forward gear 384 of the driven gears 44 of gear
means 18, which driven gears 44 are mounted on
and freely rotatable about countersha~t 43.
Drivingly mounted on sleeve 240 is a reverse gear
26~ of driver gears 40 of gear means 1~ which, in
conjunction with an idler gear 41, continuously
engages reverse gear 3~0 of driven gears 44 ~f
~ear means 18 which is bearing-mounted on counter-
shaft 43 and forms a revexse gear arrangementknown in the prior art. Mounted on land 264 of
reverse gear 262 on shaft 34 is a parking sprag
266 which is engageable at the stoppea or park
position, and such gear engagement is well known
in the pxior art. Synchronizex 46 is splined on
- 20 -
ring 375 which is rigidly splined on countexshaft
43. The synchronizer is operable by shifting fork
392. The synchronizer 46 is positioned between and
slidabl~ engageable with either the forward or
reverse gears of driven gears 44. At synchronizer
46 engagement, as drive is being provided through
engaged clutch 16, power is transmitted to the
final drive assembly 20 in either a forward or
reverse direction.
At transmission idle the prime mover 12 is
driving in.put pulley 30 through a flywheel 26,
vibration damper 28, and drive shaft 24. As sho~n
in FIG. 2A, upper halves of pulleys 30 and 36 are
shown în low belt ra~io (iOe., driver pulley 30 at
lS maximum gap opening and belt 42 at closes~ ra~ius
to drive shaft 24). Pulley~30 is utilized ~o
control the belt position or ratio and not belt
tension or output torque of the drive train. The
change of width between fixed sheave 66 and movable
sheave 68 of pulley 30 provides the change in belt
ratio in response to $he transmission control
means 22. This ratio control in the case shown in
FIG. 2A, is provided for b~ an introduction o~ a
fluid to sealed chamber 114, such as from a fluid
~5 supply means communicating with fluid passage 74
through insert 130 therein to passage 76 t chamber
98 and passage 88. A change in fluid volume into
chamber 114 will proportionally move sheave 68 to
reduce the sheave gap. As belt 42 travels from
the inner radius of pulley 30 to the outer radius,
- 21 -
~9~
the transmission belt ratio changes from low to
high with a range of about 5.4 to 1.
Purnp 136 is a*fixed to shaft 24 and only
provides lubricant to the various wearing parts of
the transmission at a rela-tively low pressure,
that is in tlle range of a~out 20 psi. Con-trol
fluid for chamber 114 passes through a counter-
drilled hole 141 of pump 136 in the face of cover
138 and thus to *luid passage 74.
Output ariven pulley 36 is also fluid operative,
however, as driver pulley 30 sheave gap decreases
the driven pulley 36 sheave ~ap increases, and in
FIG. 2A this implies that ~elt 42 would proceed
from the outer radius to the inner radius of
pulle~ 36. The sheave gap of the driven pu7ley 36
is determined by the position of movable sheave 68
of driver pulley 30 through belt 42. Control
1uid, at a line pressure controlled by control
means 22, is freely communicated to control fluid
cavity 224 o~ driven pulley 36 throush inser-t 1560
through hole conduit 154, passage 174, cha~ber 200
and passage 1~4. The piston area of movable
sheave 152 within cavi~y 224 is noticeably smaller
than its counterpart of driver pulley 30~ Control
fluid in cavity 224 is bled to *luid cavi-ty 228
through orifi.ce 218 in piston flange 208. Fluid
is transferred to cavity 228 to balance the centrifugal
component of the total pressure on either side of
flange 208 thereby avoiding a centri*ugal thrust
on sheav~ 152. The movable sheave :l52 has a bias
- 22 -
spring 226 acting on it and biasing the sheave to
minimize the sheave gap width
The through-hole conduit 154 provides a
transfer means for ~ontrol fluid for slipp~ble
starting clutch 16, which is engaged through fluid
pressure in cham~er 332, see FIG. 3. The force of
the Belleville spring 308 of clutch 16 ten~s to
maintain pressure plate 302 in the non-contacting
or open position. When the fluid pressure in
cavit.~ 332 is sufficient to overcome the Bellevill~
spring 3~8 i-orce, pressure plate 302 is pressed
- into contact with friction ~acing 340 to thereaftex
engage driven plate 304. Coolant fluid is supplied
through control means 22 and conduit 346 to cooling
fluid cavity chamber 348 of clutch 16~ At clutch
engagement pressure plate 302 contacts friction
Eacin~ 340 to dri~ingly engage driven plate 304.
Driving power is thus provided to hollow sleeve
240 of driver gears 40 through disc 336, annular
ring 342 and spline member 344~ Therea~ter,
rotational motion is communicated to forward gear
233 and reverse gear 262, which gears are rigidly
connected, to each other, ana through which shaft
34 extends~ and about which shaft 34 forward~
reverse gears 238, 262 are ~reely ro~atable.
Forward or reverse drive direction, or neutral, if
desired, is selectable by operation oE synchronizer
46. The synchronizer 46 position is slidably
operable by the fork 392 and rail 47, as known in
3Q the prior art. The forward, reverse gears 334 J
390 on countershaft 43 are in constant engagement
- 23 -
with matiny forward year 238, on shaft 340 or
idler 41, respectively~ At synchronizer 46 en-
gagement rotational motion is transferred to th~
final drive assembly 20, which assembly includes
elements such as a differential 50 and drive axle
56 as known in the prior art~
In the operation of this transmission mechanism
the pulley system 14 is in constant unidirectional
rotary motion whenever prime mover 12 is operating.
All power to the final drive assembly 20 must be
communicated from the pulley system 14 through the
slippable starting clutch 16, and forward-reverse
gear means 18~ In this arrangementJ the con-trol
means 22 controls fluid line pressure in passage
154 and fluid volume in chamber 114 based on
engine (input~ speed, output speed, throttle (not
shown) position and year shift lever 47 position~
The volume of oil in pulley 30 is controlled by
means 22 in response to each throttle position to
maintain a constant input RPM. For example,
during acceleration at one-quarter wide open
throttle, means 22 may be progra~ned to maintain a
fixed input ~PM, such as 1500 RPM input speed
while the belt ratio is be.ing varied Erom low to
high ratio. Conversely, at that throttle opening
during a condition of vehicle speed reduction~
such as from climbing a grade, the input RPM will
be maintained by changing the belt ratio toward
low through a discharge of fluid from pulley 30.
In the starting mode the control means 22 increases
the fluid pressure in clutch 16 as a function of
- 24 -
the engine input RPM ~for eY~ample, as the square
o the illpUt RPM). Therefore, at a given throttle
opening, a constant torque and a constant RPM will
be maint~ined at clutch pressure plate 302 and the
ve~icle will accelerate from rest at a constant
rate~ With the increase in vehicle speed t the RPM
of the driven plate increases a~ a fixea (geared)
ratio until it reaches the cons~ant RPM of the
clutch pressure plate 302, which aefines the ena-
point of clutch slip, or the end of the startingmode.
FIG. 6 shows the increase of clutch driven
plate speed as a ~unction of vehicle speed ~n a
curve 600. As shown there is a corresponding
- 15 vehicle speed (in miles per hour or MPH) for each
particular dri~en plate speed ~in revolutions per
m;nute or RPM). Curve 600 indicates that vehicle
speed and clutch pressure plate speed intersect
at a point 602. At that point, the starting
clutch is at the end of its slipo From the origin
until the end of clutch slip, th~ angular speed
o~ clutch reaction plate 304 rises proportionally
with vehicle speed, and this rise is dependent
upon gear ratio, not belt ra-tio. The pr~ssure
25 or driver plate 302 is rotating at a constant
speed (at a given throttle opening~.
Also in the s~arting mode at the first momPnt
~efore a vehicle has attaine~ a measurable velocity
the input torque when plotted as a predetermlned
function of engine speed can be/ for example, a
- 25 -
paraholic curve similar to a hydrokinetic device
or a centrifugal clutch~ In ~IG. 7 t curve G04
is a parabolic function showing the variatlon of
input clutch torque (in ft.-lbs.~ or net pressure
(in psi) on clutch pressure plate as a function o~
engine speed, where the abcissa commences at a
value connoting engine idle speed, rather than zero
RPM. ~lso the pressure at engine idle speed is
controlled to cancel the opposing force o~ Belleville
spring 308 so the net pressure on the clu-tch pressure
plate is zero at normal engine idle speedg and
consequently creep is avoided~ Creep is defined as
the power transfer through the drive train at stall
speed sufficient to overcome rolling resistance~
A second general ~unction 606 with a maximum
- value at point 608 is also shown. This second
function 606 represents the net engine torque at
wide open throttle as a function of engine spee~.
The intersection of curves 604 and 606, at poin~
610, indicates the stall point. This is not a
different stall point than that previously noted,
but explains the same point utilizing dif-Eerent
parameters. The continuation of the parabolic
curve 604 abo~e the stall point 610 represents the
reserve pressure at the clutch pressure plate.
The input tor~ue beyond point 610 is limited to
the maximum engine torque 60~ The control means
22 accordingly limits the rise in pre~sure to a
predetermined value 612 to provide a controlled
reserve pressure slightly above the wide open
- 26 -
throttle tQrque requirement. Correspondingly r a
suitable reserve pressure is provided at other
torques down to about 25~ of the torque at wide
open throttle. This mlnimum value also correspon~s
to the max;mum engine ~raking torque. This provides
a means to protect pulley system 14 from incurring
slip and reduces ~elt 42 loading that would
o-therwise tend to fatigu2 the bel-t.
Clutch 16 is a liquid cooled (wet~ starting
clutch.which is slippable in the starting mode as
torque is provided to the final drive assembly 20
At clutch 16 dlsengagement the fIuid pressure in
chamber 332 is removed and the Belleville spring
.. ... ;.. ... .
. ~ 308 acts to retract pressure plate 302 to the
disengaged position. This reaction is almost
instantaneous, that is, on the order o~ one-tenth
(0.1) second.
Curve 614 in FIG. 8 is generally similar -to
curve 604 in FIG. 7. Curve 614 will be used, in
conjunction with representative values rounded of~
to whole numbers for ease of cvmprehension, and
these values do not limit the present invent;on.
Curve 614 shows clutch torque p:Lotted as a function
o engine speed. In this example, wide open
th.rottle in the starting mode is indicated at
stall point 616, correspond~ng to 2100 RPM and a
clutch torque load of 140 ~t.-lbs. At this 2100
RPM engine speed, if the bel-t is at a 1:2 under-
drivP ratio/ at point 616, at this low belt ratio
27 --
8~
there is effectively a 140 ft.-lbs. clutch torque.
However, the clutch torque for a 2:1 overdrive
ratio, at this same throttle opening, is effectively
35 ft.-lbs. In this example, the engine RPM for
the 35 ft.-l~s. clutch torque on the curve is
denoted at point 618, corresponding to 1300 RPM,
which becomes the new stall point, and at this
high belt rato of 2:1, point 618 also represents
the lugging limit.
~ In other words lugging below this engine
speed is inherently avoided along with the harshness
or torsional disturbance associated with lug~ing
at very low speed particularly so with ~our cycle
engines~ At vehicle speeds below the lugging
~5 - limit, the clutch begins to slip and a torsional
disturbance associated with such lower speeds will
not be transmitted through the clutch. Relow the
lugging limit engine speedl the control means 22
will again downshift and the engine speed will
increase even at a lower vehicle speed tc thereby
remain above the lugging limit.
In a conventional CVT with a startin~ device
on the input side o~ the belt stall point is the
same in both high and low belt ratios at any given
throttle opening, and it is then necessary to add
a lock-up device in order to operate the engine in
the more efficient speed range below the stall
point and this device still does not provide an
inherent lugginy limit.
The use of a slippable starting clutch and a
forward-reverse gear mechanism provides a compact
28 -
7~
arrangement o~ elements to provide power transferO This
mechanism is in lieu of multiple clutch packs or heavier,
more complex planetary ~ear assemblies as shown in U.S.
Patent 4,342 r 238, issued August 3, 1982.
Clutch 16 is cooled through cooling paths cut
in f~iction facings 338,340 and resilient layers 341,343,
respectively. This cooling is provided by fluid passing
through the waffle pattern on the friction facing. The
coolant fluid is waste fluid, such as oil~ diverted from
a low pressure return line o~ control means 22. This fluid
does not, therefore, require added pump capacity for the
high pressure fluid line and as fluid conduit 349 is a
relatively large passage, added coolant through the clutch
avoids excess back pressure on the control means 22 These
large passages permit large volume flows at low pressures
thereby obviating high fluid pressures from a pump source
and providin~ greater cooling capacity than is presently
known.
In the illustrated embodiment, driven pulley 36
is in a centrifugally balanced condition, that is the
centrifugal component of the fluid force on either side
of flange 208 is virtually equal, thereby avoiding an im-
balance Erom a centrifugal pressure effect within chamber
2240 The clamping force and, therefore, the tension on
belt 42 is provided by khe fluid pressue ~n chamber 224 and
bias spr~n~ 150. This clamping force varies with the
~luid pressure controlled only to -that pressure required
to limit belt creep at a ~iven torquer In the prior art
it has been the practice to maintain a lar~e fixed force
on the belt 42, regardless of torque input, to thereby ~void
belt slip. The prior art overloaded belt, at part en~ine
load, increases belt fatigue and ~riction losses, and is
an added load on the engine or 1uid pressure supply system.
- 29 -
mab/
The attainment of output speed and final gear
ratio is through the single paper plate clutch where clutch
16, clutch disc 336 and pressure plate 302 are running
at the same speed, having arrived at a locked up state
without a jump or lurch, and without a speed differential
at lock-up. Those goals were attained through the use of
a forward-reverse gear mechanism in con.junction wi-th a
wet clutch while also reducing the number of parts and
total weight of the assembly~ Such advantages are very
important to the automotive industry wherein government
regulations require improved fuel efficiency; such an
improvement in efficiency is directly proportional to weight
losses. In addition, th.s is the most compact automatic
transmission currently available. The economies of
reducing the number of parts in any assembly while accom-
plishing the same task provides cost savings of both
material and assembly laborv
. , ~ ... .
The above~described transmission mechanism is also
described and is claimed in above-identified parent appli-
cation Serial No. 400,560
The operability of this transmission clearly
obviates the use of multiple clutch packs and planetary
gear sets. Furt.her the clutch as disclosed, gives an almost
instantaneous disengaging response just by releasing the
fluid pressure from the clutch. The use of the combination
of elements disclosed gives the user improved cost econo-
mies, faster :response time, bettex control, less wear of
CVT elements and better fuel economy without a creep con-
dition and without a garage shift thump and also proyides
better u-tili~ation of fluid with reduced output requirements
on the fluid pump~
- 30 -
mab/J
