Note: Descriptions are shown in the official language in which they were submitted.
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MUI.TIPLE RATIO OVERDRIVE TRANSMISSION- DIV. III
Our invention comprises improvements in a hydro-
kinetic multiple ratio power transmission mechanism having
two underdrive ratios, a direct drive ratio, an overdrive
ratio and a control system for establishing the various drive
ranges and shift patterns; more particularly it is an improve-
ment in transmission mechanisms of the kind described in
Konrad U.S. Patent No. 3,491,617 and in Egbert U.S. Patent
No. 3,31~,307. Those patent disclosures, as well as this
disclosure, relate to transmission mechanisms for use with
automotive internal combustion engines.
The present application is a division of copending
Canadian application ~erial No. 359,390 filed August 28,
1980.
The present invention provides a power transmission
mechanism having gear elements including a ring gear, sun
gear, planetary pinion and carrier for the planetary pinion.
The gear elements define plural torque delivery paths from
a driving member to a driven member to effect multiple ratio
torque ratios including an overdrive ratio and a direct drive
ratio. Clutches and brakes including a forward drive clutch
means and an overdrive brake means control the relative motion
of the gear elements and an overdrlve clutch means dellvers
input torque to the carrier as an overdrive reaction gear
element is braked by the overdrive brake means. The forward
drive clutch means, when applied, connects the gear elements
together for rotation in unison.
A valve control circuit controls engagement and
release of the clutches and brakes and includes a pressure
source and an overdrive and direct shift valve means for
controlling application and release of the forward drive
clutch means as the overdrive brake is released and applied,
respectively. A feed passage for the forward drive clutch
means communicates with the shift valve means, so that the
shift valve means controls application of the forward drive
clutch means. A pair of flow control orifices of different
size and located in the feed passages and orifice control
valve means including a 2-3 backout valve directs fluid
through the larger orifice during ratio shifts under torque
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~rom the overdrive ratio to the direct drive ratio and -through
the smaller orifice duri,ng a corresponding ratio shift with
reduced torque. A source of torque dependent throttle pres-
sure is provided and means subjec~s portions of the orifice
control valve means to the throttle pressure to actuate the
same.
The overdrive brake preferably has a double acting
brake servo with a piston that defines in part a servo release
presure chamber and a servo apply pressure chamber. The
overdrive servo is released when both pressure chambers are
pressurized. The shift valve means provides an exhaust flow
path for the release chamber when it is shifted to the over-
drive ratio position.
The forward drive clutch means preferably is adap-
ted to connect the driving member of the mechanism to a torqueinput gear element during forward drive operation. Parallel
portions of a forward drive clutch means feed passage commun-
icated with the orifice control valve means with one parallel
portion providing a greater flow restriction than the other.
The orifice control valve means is in communication with
the throttle pressure source and ~esponds to thro~tle pressure
to actuate the orific~ control valve means to a position
causing fluid to be distributed to the forward drive cIutch
means through the reduced flow restriction passage portion
with a reduction in throttle pressure below a caIibrated
low valve causing the oriflce control valve means to be con-
ditioned for distribution of fluid to the forward drive clutch '~'
means through the higher flow restriction passage portion.
Other features of the invention will become
apparent from the following description, which is made
with reference to the accompanying drawings, wherein:
Figures lA, lB and lC show, respectively, the
torque converter portion, the main gearing portion and
the tailshaft extension housing for an automatic power
transmission mechanism capable of embodying the
improvements of the invention;
Figure lD is a schematic representation of the
transmission mechanism of Figures lA, lB and IC;
Figure lE is a chart that shows the clutch
engagement and release pattern during ratio changes for
the transmission mechanism of Figures lA, lB and lC;
Figure ~ is a cross-sectional view of a partial
assembly o~ a cover and damper which form a part of the
converter mechanism shown in Figure lA;
Figure 3 is a cross-sectional view as seen .rom
the plane of section line 3-3 of Figure 2;
Figure 4 is a cross-section view as seen from
the plane o section line 4-4 of Figure 2;
Figure 5 is a chart that shows the relationship
between carburetor throttle angle at the engine and the
throttle valve pressure at the transmission;
Figure 6 is a chart that shows the relationship
bett~een line pressure and throttle pressure for reverse
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drive operation, first and second speed operation and
cutback operation in third and fourth ratios;
Figures 7A and 7B show a control valve circuit
for controlling the ratio shift pattern for the
transmission mechanism of Figures lA, lB and lC;
Figure 8 is a subassembly view of the valve
arrangement for Figures 7A and 7B illustrating the valve
positions during initial engagement of the forward drive
clutch;
10Figure 9 is a partial drawing of the valve
circuit showing the valve positions during start-up in
the manual-low range;
Figure 9A shows an enlarged view of the low
servo modulator valve seen in Figure 9;
- 15Figure 10 shows the control valve circuit
condition for second ratio lockout in the manual-low
range;
Figure lOA is an enlarged view of the 2-1
scheduling valve shown in the circuit of Figure 10;
20Figure 11 is a partial valve diagram of the
valve system when it is conditioned for~ distribution of a
scheduling pressure to the 1-2 shift valve; :
Figure llA shows the operation ~of the 2-1
scheduling valve during the mode of operation of Figure
11;
Figure 12 shows a partial valve diagram
illustrating the reverse brake servo and clutch when the
valve system is conditioned for reverse drive range;
Figure 13 shows the ~throttle valve system in
combination with the~valve circuit as a~whole;
: Figures 13A, 13B and liC show a subassembly
view of the throttle valve elements for the system of
Figure 13;
Figure 14 is a partial valve diagram showing
-~ 35 the modulated mv pressures used for ,delaying upshlfts to
the second ratio, to the third ratio and to the fourth
overdrive ratio;
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Figures 14A and 14B show the operation of the
2-3 shift valve and the 3-4 shift valve, respectively,
during delay of the upshifts;
Figure 15 shows the valves conditioned for
upshift control in the overdrive range when the gearing
is adapted for low speed ratio operation;
Figure 16 is a view similar to Figure 15 with
the valves in the overdrive range and conditioned for an
automatic 1-2 upshift;
Figures 16A, 16~ and 16C show the function of
the 1-2 capacity modulator valve and the 1-2 accumulator
valve;
Figure 17 shows a valve system in the overdrive
range when it is in condition for a 2-3 upshift at part
throttle;
Figure 18 is a partial view of the valve system
in the overdrive range when it is in condition for a 3-4
upshift;
Figure 19 shows a kick-down valve system when
the throttle valve is advanced to its maximum setting;
Figure 20 is a view of the valve system~when it
is in condition for manual-low, first gear: ratio
operation;
Figure 21: shows the valve system when it is in
2S condition for first gear engagement in the overdrive
range at closed throttle;
Figure 22 shows the valve system when it is in
condition for second~gear: operation in part throttle in
the overdrive range;
Figure 23 shows the valve system when it is in
condition for third:gear operation at 3/4 engine throttle
setting in the overdrive range;
~Figure 24 is a view of the valve system when it
is in condition for third gear operation at 3/4 engine
35 throttle in drive range number 3;
Figure 25 is a view of the valve system when it
is in condition for fourth gear operation at part:
throttle;
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Figure 26 is a view of the valve system when it
is in condition for reverse drive operation at initial
engagement at a closed engine throttle;
Figure 27 is a view of the valve system when it
is in condition for manual low operation at closed
throttle above the 2-1 downshift speed;
Figure 28 is a chart that shows the orifices in
the 2-3 backout valve that are effective ~or various
driving conditions indicated in the chart;
Figure 29 is a partial view of the valve system
showing the 2-3 capacity modulator valve and the orifice
control valve during closed throttle engagement of the
direct drive clutch, as well as during closed throttle
clutch engagement under torque;
lS Figure 30 is a view similar to Figure 29
showing the valve positions during a 4-3 torque demand
downshift; and
Figure 31 shows a coasting downshift condition
for the orifice control va}ve on the 2-3 capacity
modulator as the downshift occurs from the overdrive
ratio to the direct drive ratio.
The operation of the converter, the gearing and
- the clutch-and-brake engagement and release sequences
will be described with reference to Figure lA through~lE.
Reference numeral 10 in Figure lA shows the end of an
engine ~cranksha~t for an internal combustion engine.
Reference numeral 12 generally designates a unitary cast
aluminum ~ousing which encloses a hydrokine~tic~torque
converter 14 and a planetary gear portiôn~ 16. A
tailshaft extension housing 18 is mounted on the~
right-hand end of the housing 12 and is secured thereto
bv bolts 20.
~ Crankshaft lO is bolted at 22 to impel1er drive ~;
plate 24, which carries~a starter ring gear 26 on its
periphery. Impeller housing 28 is bolted~at a~radially
outward location 30 to the drive plate 24. Impeller
housing 28 encloses a bladed turbine 32 and a bladed
stator 34, the latter being situated between ~the flow
exit region of the
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turbine 32 at the ~low entrance re~ion o~ the impeller
blades sh~wn at 36. The hub of impeller housing 28 is
drivably connected to impeller suppor~ sleeve shaft 38
which is journallea in an opening formed in the pump
s hou~ing 40. ~ou~ing 40 is ~ecured by bolts 42 agai~st
an internal shoulder 44 ~ormed in the transmissi~n hous-
ing 12. ~ ~ta~or support sleeve shaft 46 i~ disposed
within impeller 31ee~e shat 38. It form~ a part of
p~p cover plate 48. Bladed stator 34 is mounted on
10 the stator sleeye sha~t 46 by overrunning brake assembly
.50, the latter permitting freewheeling motion of the
bladed stator ~4 in the dixection o~ rotation o~ the
impeller but preventing rotation of the bladed stator
in the oppo~ite directi~n~
TurbLne 32 include~ an outer shroud 52 which
is secured to turhine hub 5 4, which in turn is splined
to turb~ne ~leeve ~ha~t 56 located concentrically within
the slee~e shaft 46. Direct drive shaft 58 is splined at
60 to the hub 62 of an internal damper assem~ly 64.
This damper assem~ly 64 forms a resilie~t co~nection ~et-
ween the direct dri~e shaft 58 and the impe}ler hou~ing
28.
~ he damper asse~bly can best be seen by reer-
ring ~o Figures 2, 3 and 4. It includes a spring retainer
plate 66 which has recesses on one side thereof, a~ seen
at 68, f~r retai~ing damper springs 70. The hub 62 form~
a part of a radially outward drlve pl~te 72 which is
formed with angularly di posed openings 74 for receiving
the springs 70. The outar margin o~ plate 72 is formed
with recesses or no~ches 76 which receive drive tabs 78
formed on drive plate 80, the latte~ in turn being spot
welded at 82 to the inner wall of the impeller housing. -
Drive plate 80, the radial plate 72~and the end plate 66
are joined together by ri~ets 84 to form a unitary
assembly. The plate 8~ and the plate 66 form an assembly
that is adapted to ve angularly with respect to the
plate 72. That movement is resisted by the springs 70
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which are ~eated with a preload on the ends ~ the spring
openings i4. The plate 72 is provided with eLongated
slots 86 through which the rivets or pins extend thereby
accommodating relative motion between the plate-~ 78 and
5 66 with respect to the plate 72.
~ fric~ion washer 88 with friction material on
one side thereof is urged ~nto engagemen~ with the damper
hub 62 by a circular Belleville ~pring wash~r so situated
betwQen the hub 62 and the plate 66. Friction material
92 is formed also on the oppo~ite side of the hub 62.
Thus the 3ell~Yilla washer 90 provid~Y a so-called
coloumb effect to pro~ide fric~ional energy absorption
whiGh, in combination with t~e damping effect o~ the
spri~g~ ?0, provide~ an inertia damper for cushioning the
ratio shi~t ~ro~ a ~ydrokinetic drive to either a partial
or a ~echa~aldriv~ aq the transmissio~ ls~in condition
for direct driVQ operation or o~erdrive operation.
A wa~her 88 ha~ tabs that are received in
rece~ses 94 formed in a c~ntxal opening 96 of the plate
66. The right-hand end o~ the tur~ine sleeve ~haft 56
i~ splined at 98 to the hub of clutch member 100, which
is journalled at 102 on 3tationa~y support sleeve sha~t
104 that forms a part of pump cover plate 4a bolted by
bolts 106 to the pus:lp housing 40. Clutch member 100
de~ine5 an annular cylinder 108 ~or forward clutch assembly
110. An annular pi~ton 112 iq situated in the cylinder
108 and defines a pressure cham~er that can be pressurized
selec~i~ely by th~ control y~tem to effect engagement of
the clu~ch assembly 110. Clutch mem~er 100 is pro~ided
with internal spl~nes that carry externally splined olutch
discs 114. These register with internally splined clutch
discc 116 carr~ed by externally splined clutch member 118, ~ ~:
the latter in turn being splined to sun gear slee~e sha~t
120 for the planetary gear unit:16. Clutch return spring
35 122 situated between the clutch member 118 and the piston
112 normally urge the piston 112 out of engagement with
the clutch disc
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Clutch member 100 is provided also with an
externally splined portion that carries in~ernally splined
clutch discs 124. The~a are arranged in regi5try with
externally splined clutch disc3 126 that are carried by
an internally ~plined porkion o~ the rever~e clutch
element 12a, which is journalled rotatably ~n the qtation-
ary sleeve sha~t 104. Clutch discs 124 and 126 form a
part of a reverse clutch asgembly identified by re~erence
character 130.
Reverse clutch element 128 deines an annular
- cyli~der 132 whic~ receive~ an annular piston 134. Belle-
ville spring lever 13~ provides a ~orce multiplying con-
nection between the piston 134 and the pres~u~e plate 138
that acti~ate~ the clutch discs.
A21 intermediate clutch or brake assembly 140
comprisas externally 3p~ined friction disc~ that register
with splines or groo~es formed in the housing 12. A
stationary bac~up ring ~or the intermedi~te clutch or
brake, which i~ shown at 141,engages an in~ernal shoulder
on the housing 12. Internally splined ~riction di~c~ of
the clutch or brake a.~3embly. 140 are carried by an exter-
nally splined overrunning brake race 142 of an overrunning
brake a~qembly 144. The inner rac 146 for the brake
assem~ly 144 i~ secured to the reverse clutch element 128.
The friction discs for the clutch ar brake
assem~ly 140 can be applied by an annular piston 148
located in an annular cylinder lS0 formed in the pump
housing 40.
Whe~ fluid pressuxe is admit~ed to the annular
30 cylinder 150i the forca developed on the piston 148 applies
the intermediate clutch or brake thereby anchoring 5un gear
152 of the planetary geax assemb}y 16. Sun gear 152 ~ con-
nected to reverse clutch element 128 through a dri~e shell
154, which is a sheet metal torque transfer member surround-
ing th- iorward clutch sJem~ly llO.
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The compound planetary gear assem~ly 16
includa~,in addition to ~he ~un gear 152, a sun gear 156
which is of a smaller pitch diameter than the sun gear
152. A ~ir~t se~ of planeta~y pinions 158 engages ~un
gear 152 and a 3econd set of planetary pinions 160
engage~ the sun gear 156. The pinions 158 and 160 engage
each other. Al~o pinion~ 158 engage ring gear 162. Both
sets of pinions 15~ and 160 are journalled on plnion
sha~ts that are ~h~wn at 164 and 166, which ~orm a part
o~ carrier assembly 168.
A bra~e drum 170 i~ formed integrally wi~h the
carrier a~s`embly 16~. It is surrounded ~y multiple wrap
brake band 112. A ~luid pressure operated bxake ser~o
which is shown schema~icalLy in the circuit drawings to
be described later, is adapted to apply and release the
brak~ band 172. The reaction torque for the braXe band
172 i~ absorbed by the transmission housing 12.
An overrunning bxa~e 174 i9 ~ituated in series
di~position with respect to ~he brake band 172. It
20 includaq an outer race 176 carried by brake drum 170, an
inner raca L78 and overxunning bra~e rollers 180 that
register with ca~ urface formed in the race 176. Inner
race 178 is secured to the housing I2 by brake suppor~
plate 182.
Brake drum 170 forms a part o~ a compound plane- -~
tary gear carrier 168. Carrier 168 includes a sleeve
that is journalled on sun gear shaft 18Ç. It includes
also an end plate 184 which is journalled on sleeve la7
which formc a part of direct drive clutch element 188.
Sle~ve 187 is splined directly to the direct drive shaft
58. Plate 184 is splined also to dire~t dri~e clutch
element l90, which carrïes inter~ally splined clutch
discs 192 which are situated~adjacent to exte~lly splined
disc }94, the latter being carried by element la8.
: 35 Element 188 defines an annular cylinder 196 within which
is situated an annular piston 198 which is adapted to
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engage the discs 192 and 194 when fluid pressure is
admitted to the cylinder 196. Piston return spring 200
urges normally the piston 198 to A clutch release
position.
output shaf~ 202 is provided with an extension
204 that is received within sleeve 187 and journals the
clutch element 188. Shaft 202 is supported by a bushing
within a ~earing sleeve 206 which forms a part of the end
wall 208 of the housing 12.
The converter and gear system disclosed in
Figures lA, lB and lC is illustrated schematically in
Figure lD. The mode of operation of the converter and
gear system can best bé understood by referring to
Figures lD and lE. To condition the mechanism for
15 operation in the lowest speed ratio, it merely is
necessary to engage the forward clutch identified by the
symbols Cl in Figures lD and lE. At that time turbine
torque from the converter 14 is distributed through the
clutch Cl to the smaIl sun gear 156. The:overall speed
20 reduction that occurs is 2.4:1 as the ring gear drives
the output shaft, and the carrier torque is: absorbed
through the overrunning clutch ~174 (C4). If torque
reaction in the opposite direction is desired, it merely
is necessary to engage brake band 172, which is the
2S driving mode that is referred to in the following
description of the control circuit as the manual low
drive range.
To effect an automatic upshift from the lowest
ratio to the intermediate second speed ratio, it merely
30 is necessary to engage the intermedlate clutch or brake
140. Reaction torque then is distributed from reaction
sun gear 152 through the overrunning clutch~or brake 144
- to the engaged friction 140 (C5). The overrunning clutch
174 (C4) freewheels~ under these conditlons, ~thus
35 providing an automatic pick-up shift. A speed ratio
change to the third speed ratio, ~hich is approximately a
direct drive is achieved by engaging the direct drive
clutch 192 (C3). Clutches 192 and 110 being engaged
simultaneously, the transmission mechanism is in
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condition Eor operation with a 1:1 ratio, except for the
effect of converter strip, since all the elements of the
gearing rotate together in unison. At that time,
however, torque is distributed directly from tne input
shaft 10 to the carrier through the direct drive clutch
192 ~C3). The balance of the torque is distxibuted
hydrokinetically through the turbine 14 since the turbine
of the converter 14 is connected through the forward
clutch 110 (Cl) to the small sun gear 156. Because only
a portion of the driving torque is distributed
hydrokinetically, the resulting increase in the overall
mechanical efficiency of the transmission is improved in
comparison to transmission mechanisms of the kind
disclosed in the previously described reference patents
lS where the hydrokinetic torque converter is fully active
in each of the four driving ranges.
During a ratio change from the second ratio to
the third ratio, it is necessar~y to engage only a single
friction device, namely the clutch 192 (C3). The clutch
20 overrunning clutch 144 (C6) automatically freewheels as
the clutch 192 (C3) is engaged. Thus an automatic pickup
shift from the second ratio to the third ratio is
achieved in a nonsynchronous fashion. The valve
mechanism that is used ~to establish this shift will be
25 described subsequently.
A ratio change from the third direct drive
ratio to the overdrive ratio is obtained by engaging the
overdrive brake band shown at 210 in Figure lA and by
releasing the front clutch. The corresponding reference
30 symbol in~Figure lD and lE is Bl.
The overdrive brake band 210~surrounds clutch
member 130; and since clutch member 130 is connected
through the drive shelI 154 to the larger sun gear 152,
sun gear 152 acts as a reaction point during overdrive
35 operation as torque is delivered from the engine
crankshaft through the shaft 58 and through the clutch
192 (C3) to the carrier for the planetary gear unit.
This overruns the ring gear 162 and the output shaft 202
relative to the speed of the crankshaft.
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Reverse drive is obtained by engaging clutch
130 ~C2) and engaging brake band 172 (B2). With the
carrier braked by the brake band B2, it acts as
reaction point and the sun gear 152 acts as a torque
input element thus driving the ring gear 162 in a reverse
- direction.
The control valve system for controlling the
ratio changes and driving modes for the transmission
mechanism of Figures lA, lB and lC is illustrated
schematically in Figures 7A and 7B. The function of the
various valve elements of Figures 7A and 7B will be
described subsequently with reference to .Figures 8
through 27. For purposes of identifying the various
valve elements of the circuit, refer~nce now will be made
in a general fashion to Figures 7A and 7B.
The source of pump pressure for the control
circuit is pump 212. It comprises internal pump gear
teeth 214 which mesh with the external pump gear teeth
for pump 216, the gear teeth 216 being driven by impeller
20 support sleeve shaft 38 as shown in Figure lA.
The pressure developed by the pump 212 is
regulated by the main pressure regulator valve 218. A
first regulated output pressure from the main oil
pressure regulator valve 218 is distributed to the
25 converter 14. The fluid supplied to the converter 14
circulates through the converter and transfers to cooler
220 and to the lubrication circuit for the transmission
mechanism. Converter relief valve 222 located on the
upstream side of the converter 14 prevents overprèssure
30 in the converter torus circuit.
One of the elements of the control circuit that
:controls the timing of the ratio change from direct to
~:overdrive is the aacumulator 224 which has a piston, one
side of which is subjected to the apply pressure on one
35 side of an overdrive servo 227 for brake band 210, the
other side of which is subjected to pressure regulated by
the main regulator valve 218. ~
A ratio change from the lowest ~atio to the
intermediate ratio occurs upon application of the
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intermediate clutch 140, the shift quality and timing of
that shift is controlled by 1-2 capacity modulator valve
226 and by the 1-2 accumulator valve 228. During
operation in the manual low range to be de~cribed, a
ratio change from the intermediate ratio ~o the lowest
ratio is timed by 2-1 scheduling valve 230, which is a
regulator valve that distributes a pressure to the lower
end of the 1-2 shift valve 232, the latter in turn
controlling distribution of pressure to the intermediate
clutch 140 through the 1-2 capacity modulator valve.
Ratio changes from intermediate to the direct
drive ratio are controlled by the 2-3 shift valve 234,
which is in communication with manual valve 236, the
latter receiving regulated pressure from the pump and
distributing it to the 2-3 shift valve and the 1-2 shift
valve. The manual valve selects the drive mode that is
desired, as will be explained subsequently.
Ratio changes from the direct drive ratio,
which is a split torque drive as explained previouslyj to
the overdrive ratio is controlled by 3-4 shift valve 238
through the intermediary o~ the 3-4 shuttle valve 240 and
the overdrive servo regulator valve 242.
~ Reduced throttle and zero throttIe ratio
changes from the third ratio to the fourth ratio are
25 controlled by 3-4 upshift; pressure control backout valve
244, which is sensitive to throttle pressure received
~rom throttle valve pressure limit valve 246. A reduced
engine throttle or zero~engine throttle ratio change~from
the second~ratio to the third ratio is controlled by 2-3
30 upshift pressure control backout valve 248 which
regulates the timing of the engagement and disengagement~
of the direct clutch 192.
The timing and shift timing of the ratio change
from the~intermediate ratio to the direct drive ratio
35 upon movement of the 2-3 shift valve, the quality of the
shift being control~led in part by 2-3 accumul~ator 252.~ A
speed signal which ;is used for the various shift
functions is developed by a governor assembly 254 which,
as explained ;previously, is drivably connected to the
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output shaft 202 shown in Figure lC. That signal
cooperates with a torque signal referred to in the
sp~cification as a throttle valve signal which is
developed by throttle valve 256. The torque signal
received from the throttle valve 256 acts upon the shit
valves, more particularly the modulator valves for the
shift valves. A ratio change from the second ratio to
the direct drive ratio is timed by the output signal
received from 2-3 modulator valve 258 which regulates the
TV limit pressure received from the TV limit valve 246
before it is distributed to the spring side of the 2-3
shift valve 234. Similarly, TV modulator valve 260
controls the magnitude of the throttle pressure made
available to the 3-4 shift valve 238, thus providing the
15 necessary shift delay during acceleration, The 2 3
throttle pressure modulator valve 258 also is directed to
the 1-2 shift valve 232 and similarly delays the 1-2
upshift.
The pressure made available to low-and-reverse
20 brake servo 130 is regulated by a low servo modulator
valve 262 which reduces the magnitude of ~he pressure in
the servo as the mechanism is conditioned for low speed
ratio operation but which allows a pressure build-up to
occur during reverse drive operation. Brake band 172 is
25 applied both in low and reverse.
Referring next to Fiyure 8, there is shown a
composite view of the valve elements and have indicated
by appropriate shading those elements that are actuated
and which are pertinent to the conditioning of the~
30 mechanism for forward drive operation following initial
engagement of the forward drive clutch. The pump 212
distributes pressure to the main regulator valve 218
which comprises a valve spool having three spaced valve
lands 264, 266 and 268. The valve spool regulates the
35 pressure at a value that is determined by the value of
the force of springs 270 acting in an upward direction on
the valve spool. That force is complemented by the
forces distributed to the valve spool by oil pressure
booster valve 272, wrlch comprises three spaced velve
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lands 274, 276 and 278 of progressively decreasing
diameter. Pressure is regulated by the main regulator
valve 218 and distributes the regulated pressure to
passage 280. The pressure is made available to the main
pressure regulator valve 218 in passage 282, which
extends to the converter 14. Passage 280, which contains
regulated pressure, communicates through a check valve
control orifice plate 284 with the 3-4 accumula~or which
comprises a piston 286 that cooperates with accumulator
chamber 288 to define opposed pressure chambers. When
the lower pressure chamber is pressurized, the piston 286
moves upwardly against the force of aGcumulator spring
290. Pressure is distributed to the upper end of the
accumulator piston through passage 292.
Line pressure passage 294 extends from
regulated line pressure passage 280 to the manual valve
236 which includes a valve spool 296 having valve lands
298, 300 and 302. Valve spool 296 can be~shifted to any
one of the positions indicated in Figure 8 by reference
characters P, R, N~ D, 3 and 1. When the manual valve
236 is positioned as-shown in Figure 8, it is capable of
conditioning the control valve system for automatic
operation in any of the four forward drive ranges.
Control pressure is distributed to the manual
valve 236 from line 280 through passage 294 to the space
between the valve lands 296 and 298, which causes control
pressure to be distributed to throttle valve 256 and to
the 2-3 shift valve 234. Pressure is distributed through
the 2-3 shift valve 234 through passage 304 and through~
that valve to passage 306 which extends to the oil
pressure booster valve 272. The pressure in passage 306
acts on the differential area of lands 274 and 276 which
produces a force that augments the force of the valve
spring 270 so that upon a 2-3 upshift the regulated
35 pressure made available to the control circuit is reduced
to a value that is not in excess of the pressure that is
required to maintain direct clutch engagement.
Line pressure from the main pressure regulator
valve 218 is distributed also through the~ manual valve
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236 to passage 308 which extends to the governor assembly
254 and to the 3-4 shift valve 238, That pressure passes
through the 3-4 shift valve 238 to the orifice control
valve 250, passage 310 providing the fluid communication
between the 3-4 shift valve and the orifice control
valve. Pressure in passage 310 passes directly from the
orifice control valve 250 to the 2-3 backout valve 248
through passage 312. The fluid connection on the
downstream side of the 2-3 backout valve 248 is provided
by passage 314 which extends to the forward clutch 110
and pressurizes the annular piston for the forward
clutch. The same pressure is distributed through check
valve 316 to the upper side of piston 318 for the 2-3
accumulator 252. The pressure in the accumulator chamber
on the upper side of the piston 318 develops a force that
opposes the accumulator spring ~orce of spring 320. As
the clutch pressure builds up in the forward clutch,
corresponding pressure builds up on the top side of the
piston 318 and strokes the piston 318 in a downward
direction against the opposing force of the spring 320
thus providing a gradual pressure increase that cushions
clutch engagement.
An orifice A (see Figures 29 - 31) is located
in passage 314 and pressure distributed through the 2-3
backout valve 248 from passage 312 to passage 314 must
pass through that orifice, which controls the rate of
engagement of the forward clutch.
Regulated line pressure is distributed to the
governor assembly 254. This governor assembly 254
3Q comprises a pair of spaced valve lands 322 and 324 of
differential area. It includes also an exhaust orifice
326 controlled by valve land 324. A valve spring urges
the valve lands in a radially inward direction, thus
producing a modulated pressure in governor pressure
35 passage 327. This is a measure of the rotating speed of
the output shaft 202. For a particular description of a
governor assembly of the kind shown in Figure 8,
reference may be made to U.S. patents Nos. 3,431~,928;
2,711,749; 2,889,844; 2,911,987; 3,048,184 and 3,139,102.
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18
Governor pressure in passage 327 is distributed
to the upper end of both the 1-2 shift valve 232 and the
upper end of the 3 4 shift valve 238. Governor pressure
is distributed also through governor pressure passage 330
to the lower end of the valve spool for the 2-3 shift
valve 234.
Reference will be made in the following
description of Figures 9 through 27 to the various
control functions. Some of these functions are similar
to those functions described in prior art U.S. patents
Nos. 3,336,815; 3,424,037; 3,327,554; 3,400,612;
3,593,598; 3,095,755; 3,446,098; 3,393,585 and 3,295,387.
Those functions that are not described in those prior art
patents will be described more particula~ly in this
lS specification. More particularly this specification will
describe the function and operation of the throttle valve
system and the relationship of the throttle valve system
to the 2-3 backout valve 248 and the 3-4 backout valve
244, the fail-safe feature of the throttle valve system
20 and the throttle pressure versus travel characteristic of
the throttle valve assembly. It will describe -also the
function of TV limit valve 246, the 3-~ bac~out valve
244, the 2-3 backout valve 248, and the 2-3~ capacity
modulator 248 and its'relationship to the 2-3 accumulator
25 252. The orifice control valve 250 which acts in
combination with the 2-3 capacity modulator valve 558 and
the 2-3 accumulator 252 also will be described in
particular.
The overdrive brake band is applied by servo
30 227 as explained previously. That servo includes a
piston 328 (see Figure 7A) positioned in an overdrive
servo cylinder in cooperation with a cylinder to define
two pressure chambers indicated in Figure 7A as the
release pressure chamber and the apply pressure chamber,
35 the former being above the piston 328 and the latter
being below the piston 328. Pressure is distributed from
the manual valve 236 when it is positioned as shown in
Figure 8 to the~2-3 shift valve 234 through passage 331
and through the 2-3 shi~t valve 234 to passage 332 and
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19
the release side of the servo piston 328 thereby
disengaging the overdrive servo 227 and maintaining it in
a~ cff position. Line pressure from the manual vaLve 236
is dis~ributed also through passage 334 to the 1-2
accumulator valve 238 and through connecting passage 336
to the 1-2 shift valve 232. The presence of pressure in
passage 334 will cause the 1-2 accumulator valve 228 to
be stroked in an upward direction to condition the
accumulator valve 228 for controlling the subsequent
upshift from the low ratio to the intermediate ratio as
will be explained subsequently.
The 2-3 backout valve 248 comprises a valve
spool having spaced valve lands 338, 340, 342, 344 and
346 . A valve spring acts on the land 346 to urge
15 normally the valve spool of the 2-3 backout valve 248 in
the left-hand direction as seen in Figure 8. When it is
in that position, communication is established between
passages 312 and 314 through the orifice A (Figures 29 to
31) as explained previously. In Figure 9, there is shown
20 the condition of the valve elements for a control system
when the manual low valve 236 is shifted to the manual
low start position No. 1. At that time regulated line
pressure from passage 294 is distributed to passage 308
through the space between valve lands 298 and 300, thus
25 controlling the application of the forward clutch 110 as
explained previously wi~h reference to Figure 8. When
the manual valve spool 296 is positioned as shown,
however, pressure is distributed around valve land 300 to
line pressure passage 348 which extends to the 1-2 shift~
30 valve 232. Shift valve 232 comprises a valve spooI
having a valve land 350 and a valve land 352 which
accommodate transfer of pressure from passage 348 to
passage 354 extending to the low servo modulator valve
262.
Modulator valve 262 is best seen in Figure 9A.
It comprises a valve spool having lands 356 and 358 of
differential diameter. The pressure of pas~sage 362
creates a pressure force on the differential diamèter
which opposes the force of valve sprlnq 36'. Thls
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produces a regulated reduced pressure in passage 362 on
the downstream side of the valve 262, reverse pressure
passage 364 acting at this time as an exhaust port. The
regulated pressure in passage 362 is distributed to the
low and reverse servo 172. The reduced pressure in
passage 362 acts on the top of land 358 ko oppose the
force of the spring 365. Thus the low-and-reverse servo
becomes applied with a reduced pr0ssure that is
sufficient to maintain manual low operation. The
pressure that is applied to the low and reverse servo 172
is lower than the pressure that is necessary for reverse
drive operation. Hence, excessive pressure is not used
because of the operation of the low servo modulator valve
262. The overrunning brake 174 will not overrun when the
band is applied. Thus the transmission is capable of
engine braking. When the valve system is in a condition
as shown in Figure 9, the mechanism is incapable of
shifting to the second ratio. This function can be
understood best by referring to Figure 10. As seen in
Figure 10, the control pressure is made available to
passage 348 and is distributed to the 1-2 shift valve
232. It passes through the 1-2 shift valve 232 to the
passage 354, as explained previously. Pressure in
passage 348 is distributed through 3-way check valve 366
to passage 368 to the lower end of the 1-2 shift valve
232.
The 1-2 shift valve 232 includes, in addition
to the valve lands 350 and 352, a valve land 370 of
larger diameter than the diameter of land 352, a land 372
30 and a land 374. Pressure in passage 368 is distributed
to the lower end of the land 374 and urges the 1-2 shift
valve 232 in an upward direction against the opposing
force of governor pressure acting on the upper end of the
land 370. Line pressure also is distributed from passage
35 348 and through passage 376 to the 2-3 TV modulator valve
258. It passes through that valve to the differential
area of lands 352 and 370, thus contributing to the
upward force acting on the 1-2 shift valve spool 232.
'" I 1 ~0~9
21
Pressure passes through passage 354 to the 2-1
scheduling valve 230 as described earlier. Pressure from
passage 368 is distributed also to the lower end of land
374 to supplement the upward hydraulic force on the 1-2
shift valve 232. When the 2-1 scheduling valve is in the
downward position, line pressure from passage 352 is
distributed directly to passage 377, which causes the 1-2
shift valve 232 to move in an upward direction and to be
locked in that position. For purposes of clarity the 2-l
scheduling valve 230 has been shown in an enlarged form
in Figure 10A~ The 1-2 shift valve 232 then will be
incapable of effecting a ratio change to the intermediate
ratio regardless of the magnitude of the governor
pressure acting on the upper end of the land 370.
If the manual valve 236 is moved to the manual
low position from either the overdrive range of the
direct drive range, the transmission will shift first to
the second ratio, assuming that the vehicle is travelling
at a cruising speed in third or fourth ratio. As the
20 speed decreases; an automatic downshift will occur to the
first ratlo. To control this shift the 2-l scheduling
valve 23Q shown in Figure 11 and in Figure llA is used.
The 2-l scheduling valve 230 determines the pressure
under which a 1-2 shift valve wilI move to the downshift
25 or first ratio position.
In Figures 11 and llA it i5 seen that the 1-2
shift ualve 232 first is moved during cruising in the
third ratio or the fourth ratio to the upshift position
under the influence of governor pressure. When it is
30 upshifted, passage 354 ;becomes exhausted through exhaust
orifice 380 in the 1-2 shift valve. Passage 376, which~
is pressurized with line pressure as explained~ with
reference to Figure~lO, communicates with passage 382
through the 2-3 modulator valve~ 258, thus distributing
` 35 pressure to the 2-l scheduling valve 230. The pressure~
acts on the differential area of land 384 and 386 of~the
2-1 scheduling valve~ 230. The force produced by ~the
pressure on that diffential area is opposed by the force
of valve sprlng 388~ Thus the valve 230 acts as a
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regulator valve to produce a 2-1 scheduling valve
pressure in passage 3so which is distributed to the lower
end of the 1-2 shift valve land 374. The 1-2 shift valve
is controlled by the magnitude of the 2-1 scheduling
valve pressure in passage 390, line pressure is made
available to the 2-1 scheduling valve through passage
354.
With the regulated pressure acting on the shift
valve land 374, the shift valve will move to tha low
ratio position. Thus the transmission will be locked in
the low ratio as explained with reference to Figure 10.
Full line pressure thus acts on the lower end of land 374
since passage 382 is brought into communication with
passage 390 and with passage 377.
The 2-1 scheduling valve acts as a pressure
regulator for producing a shift point establishing
pressuxe for the 1-2 shift valve 232 as the vehicle is
coasted from a cruising condition to a low speed
condition following movement of the manual valve to the
20 number 1 range. Upon a decrease in governor pressure to
a calibrated value, the 2-1 scheduling valve 230
functions merely to transmit line pressure to the lower
end of the land 374 as shown in Figures lOA and 10.
Figure 12 shows the condition of the control
25 circuit` when it is in a condition for reverse drive
operation with the reverse clutch 130 engaged and the
low-and-reverse brake band 172 applied. The manual valve
236 is shifted to the position R as indicated in Figure
12. Line pressure from the line pressure llne 294 is
30 transferred through the manual valve space between lands
300 and 302, thus pressurizing passage 348 which extends
to the space between the lands 350 and 352 of the 1-2
shift valve 232. That pressurizes passage 354 which
~ extends to the low servo modulatox valve~ 262. Pressure
35 is distributed also from line pressure passage 294
through the manual valve 236 to the passage 394, which
also extends to the low servo~modulator valve 262. A
fluid connection to the low servo modulator valve 262 and
the 1-2 shift valve 232 at this time is established by
23
the pressurized passage 354. The output side of the low
servo modulator valve 262 communicates with the
low-and-reverse brake servo 172 through passage 362
previously described, so that the low-and-reverse servo
172 is pressurized with a maximum line pressure,
unreduced by the low servo modulator valve 306.
Passage 394 which is pressurized upon movement
of the manual valve 236 to the reverse position R
communicates with reverse clutch feed passage 396.
Passage 394 also communicates with the oil pressure
booster valve 272 and acts on the differential area of
lands 276 and 278, thereby supplementing the force of the
valve spring 270 to produce an augmented circuit pressure
during operation in reverse drive.
In Figures 13, 13A, 13B and 13C, there is shown
the throttle valve system and its relationship to the
other elements of the circuit. Throttle valve assembly
256 is supplied with line pressure through passage 294,
as explained previously. Throttle valve pressure passage
400 communicates with the output side of the throttle
valve assembly 256. The throttle pressure in passage 400
is distributed to the left hand side of 2-3 backout valve
248 and acts on the end of valve land 338 to urge the 2-3
backout valve in a right hand direction as seen in Figure
13. Passage 400 distributes also throttle pressure to
the lower end of the 3-4 TV modulator valve 260 at the
base of the 3-4 shift valve 238. The 3-4 TV modulator
valve 260 is a valve spool that is subjected to the
spring force of valve spring 402 in the 3-4 shift valve
assembly. The same spring 402 acts in an upward
direction on the 3-4 shift valve 238. Passage 404
communicates with the valve chamber in which the 3-4 TV
modulator valve 260 is situated and extends to the
orifice control valve 250. In the condition shown in
Figure 13, passage 404 is exhausted through the orifice
control valve 250 and through passage 406, which
communicates with passage 408 through 3-way check valve
410, passage 408 being exhausked through the manual valve
exhaust port 412. Thus the 3-4 TV modulator valve 260
80Bg
24
modulates the pressure in throttle pressure passage 400
~o produce the shift pressure signal in passage 414 which
acts on the lower end of the 3 4 shift valve 238 to
supplement the force of the valve spring 402.
Passage ,400 communicates directly with the TV
limit valve 246. This valve comprises a valve spool 416
having spaced valve lands which provides communication
between passage 400 and the TV limit pressure passage 418
and which provides also a differential diameter on which
the output pressure in passage 418 may act to oppose the
force of the spring 420.
The TV limit valve 246 establishes an upper
limit for the pressure in passage 418. When the pressure
in passage 400 exceeds an established Iimit d,etermined by
the calibration of the TV limit valve 246,~ the vaIve
spool 416 will move upwardly so that it begins to
regulate and produce a modified pressure in passage 418.
Passage 418 extends to the 2-3 TV modulator valve 258
located at one end of the 2-3 shift valve 234. : Valve
20 spring 422 acts on the 2-3 shift valve:as well as the 2-3
modulator valve 258. The 2-3 modulator valve 25~ thus is
capable of establishing a modulated pressure in passage
424, which acts:on the upper end of the 2-3 shift valve
234 and on the differential area of the 1-2::sh~lft valve
25 defined by valve lands~352 and 370, thus producing a
shift delay force on the 1-2 shift valve~ Under the
condition shown in Figu:re 13, the exhaust path: fo~r
passage 424 is passage: 376 since it communicates wi:th
exhausted passage 408.
The TV limit pressure in passage 418 is
distributed:also:to one end of~the 3-4 backout valve 244.
That valve comprlses a valve spool :having differential~
diamèter valve lands 426 and 428. The TV limit valve
~' pressure in passage 418 is distributed also to the~:lower
end of the oil pressure booster valve 272 and acts on the
differential diameter of lands~ 274 and 276, : t-hus
providing an:increased circuit pressure upon an increase
in the value of the throttle pressure. The influence of
the throttle pressure on the circuit pressure, however,~
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8~9
is limited by the TV limit valve 246. Line pressure from
the pump is supplied to the throttle valve 256 whenever
the engine is running and throttle pressure is developed
in passage 400. As soon as the engine throttle is opened
slightly, the ~hrottle pressure tha~ is developed ir.
passage 400 produces a force on the 2-3 backout valve 248
that causes the 2-3 backout valve 248 to move in a
right-hand direction. The upper limit for the throttle
pressure that is established by the TV limit valve 246 in
one operating embodiment of this invention is about 85
psi. If the TV pressure falls below 85 psi, it will
distribute unregulated TV pressure to the passaga 418.
If the TV pressure in passage 400 exceeds 85 psi, the
pressure in passage 418 will not rise above that value.
The TV pressure is applied also to the 3-4 TV modulator
valve 260 to produce the 3-4 shift and the output of the
TV limit valve 246 is applied to the 2-3 modulator valve
258 to produce a modulated TV pressure for controlling
the 2-3 shift and the 1-2 shift. The 3-4 backout valve
244 also is controlled by the TV pressure at closed
throttle when the TV pressure in passage 400 is zero.
The 3-4 backout valve regulates the pressure in
the overdrive servo release chamber as apply pressure is
applied to the overdrive servo as will be explained
subsequently, thereby cushioning the operation of. the
overdrive servo 227 during a so-called minimum of zero
throttle bac~out ratio change from the third ratio to the
fourth ratio.
TV limit pressure in passage 418 acts on the~
30 differential diameter of lands 276 and 278 of the oil
pressure booster valve 272, thereby increasing the
circuit pressure as throttle pressure increases, thus
Line pressure will be boosted in proportion to TV
pressure up to about 85 psi TV pressure. But beyond that
35 there ~is no other boost due to increases in throttle
valve pressure. This avoids the possibility of
development of excessive line pressures which will~cause
damage to the pump and to the clutches and brake servos.
0 ~ 9
26
As seen in Figures 13A, 13B and 13C the
throttle valve 256 comprises a valve spool with two
spaced valve lands 430 and 432. A third valve land 434
on a separate valve element is situated in a valve sleeve
which defines a pre~sure chamber 436 in which is disposed
throttle valve spring 438. A throttle valve plunger 440
is located in alignment with the valve spool of throttle
valve 256, and it comprises a single valve land slidably
situated in the throttle valve bore. Pressure is
distributed through the throttle valve bore to passage
294. Exhaust ports are located in the throttle valve
bore adjacent land 430, as shown at 442, and at a
location intermediate lands 440 and 430 as shown at 444.
Valve spring 446 is located between the thro~ttle plunger
that carries land 440 and the valve spool for throttle
valve 256.
Pressure chamber 436 communicates with pressure
chamber 448 and with the space between the valve lands
430 and 432, crossover passage 450 providing such
communicating. Passage 450 communicates also with the
space between lands 440 and 430. An orifice 452 is
located between crossover passage 450 and the space
between lands 440 and 430.
As the engine throttle control 453 (Figure 13A)
is advance, the throttle plunger moves the land 440 and
compresses the spring 446 thereby causing the throttIe
valve spool 256 to modulate the pressure in passage 294
to produce a resultant throttle pressure in passage 400.
The regulated throttle pressure acts on the left hand
side of the land 440 thereby assisting in the movement of
the throttle plunger and eliminating the high driver
effort that is sometimes necessary to actuate a
transmission throttle valve upon movement of the engine
throttle.
A mechanical linkage mechanism is disposed
between the engine carburetor throttle and the throttle
plunger and the magnitude of the TV pressure is
determined by the force of the TV spring 446. The effort
required to compress the spring is reduced by the
1 1~8089
so-called pressure feedback feature and a uniform
actuating ~orce then is available since the greater
compressio~ of spring 446 is offset by the increase in
the pressure force acting on the left hand side of the
valve land 440. The linkage interposed between the
throttle plunger and the engine carburetor throttle
includes a torsion spring (schematically shown at 455 in
Figure 13A) which tends to move the throttle plunger
toward the wide open throttle position if the linkage
from the carburetor should become disconnected. The
torsion spring, whenever the engine is running, will move
the plunger towards the wide open throttle position thus
tending to increase the throttle pressure to its maximum
value. This, of course, results in a maximum line
pressure and that maximum line pressure is then available
whenever a linkage failure occurs, thereby preventing the
clutches and brake bands of the transmission from
slipping and failing if the engine is operated under
these conditions at heavy throttle.
Figure 13A illustrates the closed throttle
condition. At that time the throttle plunger assumes its
maximum leftward position. The force of the spring 446,
even when the engine throttle is closed, is sufficient to
overcome the force of the preload~spring 436 acting on
the right hand end of the throttle valve land 434. The
regulated throt~le pressure acts on the right hand end of
the land 434 to resist the movement of the plunger thus
producing a regulating action. The orifice 452 at closed
throttle tends to leak a certain amount of~ throttle
30 pressure through the exhaust port 444. At closed
throttle passage 400 is in communication with the space
between lands 440 and 430, and since that space is
exhausted through exhaust port 444 the magnitude of the
throttle pressure in passage 400 made available to the
control circuit also is zero. Movement of the engine
throttle from the closed throttle setting to an initial
small movement will cause the land 440 to bIock the flow
through the orifice 452. Thus the throttle valve
pressure in passage 400 will rise immediately from a
28
value zero to whatever value exists in the passage 450.
This is ~he condition that exists in the Figure 13B.
~ igure 13C shows ~he condition of the valves
during wide open throt~le or kick down condition. When
the engine is operated at full throttle, the throttle
linkage positions the plunger as shown in Figure 13C and
the plunger contacts the throttle valve 256 and moves it
out of its regulating position so that it opens up the
line pressure in passage 294 to the throttle pressure
passage 400. Thus the throttle pressure in passage 400
immediately arises to the full line pressure that exists
in passage 294.
In Figure 14, 14A and 14B, there is illustrated
the modulated pressures and other pressures that are used
to delay the automatic upshifts for the 2-3 shi~t valve
and the 3-4 shift valve 238 as well as for the 1-2 shift
- valve. Governor pressure in passage 452 acts on lower
land 454 of the 2-3 shift valve 234. That valve includes
also valve lands 456, 458, 460 and 462.
The 2-3 shift valve 234 is urged in a downward
direction as~ seen in Figure 14 by the valve spring
disposed between the 2-3 modulator valve 258 and the land
462 and by a valve spring that acts on the upper side of
the land 460. Line pressure from passage 304 is
25 distributed through the space between lands 456 and~ 454
to the passage 306 extending through the booster valve
272 as explained previously. Passage 330 extends to the
space between lands 460 and 458, such space communicating
with the valve in the position shown in Figure 14 with
30 passage 332 extending to the overdrive servo release
chamber on the upper side of the piston 328 of servo 227.
The 3-4 shift valve 238 has three valve lands
as shown at 464, 466 and 468 in Figure 14. It includes
also a valve~spring 470 that moves the valve 238 in an
35 upward direction as seen in Figure 14 against the
opposing force of governor pressure. Governor pressure
passage 328 transfers governor pressure to the upper end
of the land 454. The modulated throttle valve pressure
in passage 414, previously described with reference to
O B 9
29
Figure 13, establishes a downshift force on valve land
468. Passage 404 acts as an exhaust passage for 3-4 TV
modulator valve 260 since it is exhausted under the
conditions shown in Figure 14 through the orifice control
valve 250, 3-way check valve 410 and passage 408. The
3-way check valve 410 communicates with the orifice
control valve 25~ in passage 406.
The 2-3 modulator valve 258 is a single
diameter valve spool that that is subjected to the TV
limit pressure in passage 418. I~ produces a pressure
force on the 2-3 shift valve that opposes the governor
pressure force due to the governor pressure in passage
452. The magnitude of the modulated pressure acting on
land 462 is determined by the TV limit pressure and the
spring force.
The modulated pressure in passage 424 for the
2-3 shift valve ,34 acts also on the 1-2 shift valve 232.
The 1-2 shift valve comprises spaced valve lands 370,
352, -350, 372 and 374 as seen in Figure 14. The
20 modulated pressure in passage 424 acts on the
differential area defined by lands 370 and 352 to create
a downshift force or a shift delay force on the 1-2 shift
valve 232 that opposes the force of the governor pressure
in passage 328. Line pressure in passage 334 and in
passage 336 acts on the differential area of lands 372
and 374 to create a further shift delay. Passage 334 is
not shown in a pressurized state in Figure 14, however,
since the manual valve 236 in that Figure is shifted to
the neutral position rather than position D.
A shift delay pressure on the 2-3 shif~ valve
234, in addition to the shift delay produced by the
modulated pressure in passage 42A, is developed by the
line pressure in passage 304 which acts on the
differential area of shift valve lands 456 and 454.
Shift delay pressures acting on the 3-4 shift
valve 238, in addition to the shift delay pressure
developed by the modulated pressure in ~line 414,~are the
pressure forces due to the pressure in passage 308. That
pressure acts on tbe differential area of~lands 464 an~
0 ~ 9
466 and on the separate differential area defined by
lands 466 and 468.
In Figure lS there is shown an operating mode
of the con~rol valve circuit when tha manual valve 236 is
shifted to the drive range position when the vehicle is
in first gear ratio. This is the operating mode that
conditions the mechanism for automatic ratio changes as
will be explained with reference to Figures 16, 17 and
18. Line pressure in the Figure lS mode is distributed
to the 1-2 shift valve 232 through passage 336 and 334
and that line pressure is blocked by lands 372 and 374.
Pressure is distributed also from passage 336 to the
lower end of the 1-2 accumulator valve 228 thus causing
the 1-2 accumulator valve piston 482 to be stroked in an
lS upward direction against the opposing force of spring 484
in preparation for a 1-2 automatic upshift.
Line pressure is distributed also from passage
304 to the 2-3 shift valve 234 at the space between valve
lands 456 and 454 as seen in Figure 15. Line pressure
20 from passage 330 extends through the 2-3 shift valve 234
to the passage 323 which extends to the release side of
the overdrive servo 227. The forward clutch also is
applied as pressure is distributed through passage 308,
through the 3-~ shift valve to crossover passage 310 and
25 through the orifice control valve to passage 312 and
hence through the 2-3 backout valve 248 to the passage
314. This circuit was described previously with
reference to Figure 8. It should be noted that the
orifice control valve 250 is urged in an upward direction
30 at this time, as seen in Figure 15 as the pressure in
passaqe 310 acts on lower valve land 486. The orifice
control valve 250 includes, in addition to the land 486,
valve land 488 and a valve spring 490 which urges the
valve in a downward direction as seen in Figure 15.
35 Pressure in passage 310, which is distributed to the
forward clutch 110 through the circuit previously
described, is made available also to the upper end of the
2-3 accumulator 252 which was described also with
reference to Figure 8. The accumulator 252, as shown in
0~
31
Fiqure 15, is fully stroked in contrast to the position
that is illustrated in ~igure 8.
During initial engagement of the forward clutch
the time required to stroke the accumulator piston delays
the pressure buildup in the forward clutch 110 and causes
a cushioned clutch application. The 3-4 shuttle valve
240 also is in condition for operation. It is comprised
of a valve spool 494 having spaced valve lands 496 and
498. The valve spool is biased in an upward direction,
as seen in Figure 15, by valve spring 500 seen in Figure
8 but not in Figure 15. The 3-4 shuttle valve spool 494
is pressurized at its upper end with line pressure which
is distributed to it through passage 502. This passage
communicates with passage 314 through one-way check valve
504, passage 314 being pressurized as described
previously with reference to Figure 8.
The shi~t valves receive a speed signal
pressure as described in Figure 8, but the magnitude of
that signal is not sufficient to cause them to shift
against the opposing shift delay pressures~and against
the opposing forces of the shift valve springs, It will
be observed in Figure 15 that the forward clutch 110
receives its pressure ~hrough the 3-4 shift valve 238 so
that when the latter is upshifted to fourth ratio
25 position, the forward clutch 110 will become disengaged.~
The throttle pressure developed by~the throttle
pressure valve 256 is distributed in the condition shown
in Figure 15 throughout the valve circuit in~the same
fashion described previously with reference ko Figure 13.
30 Throttle pressure causes the backout valves, both the 3-4
backout valve and khe 2-3 backout vaIve to be shifted
against their respective springs. It should be noted
also in Figure 15 that distribution of control pressure
through the 2-3 shift valve 234 to passage 306 occurs to
35 develop a line pressure boost. Diskribukion cf pressure
khrough that passage 306 is interrupted, however,
immediately upon ~upshifk of kh~e 2-3 ~shift valve 234 to
iks direck drive position, thus causing a cutback in the
magnitude of th regulated line pressure output of the
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32
main regulator valve, It should be noted also in Figure
15 that throttle pressure from the throttle valve 256 is
distributed to the lower end of the land 278 of the oil
pressure booster valve.
hine pressure is distributed from passage 334
to passage 336 to the space between lands 37~ and 374 on
the 1-2 shift valve thereby conditioning the 1-2 shift
valve for a subsequent 1-2 upshift.
Line pressure from pump 212 is distributed
through the passage 280 to the differential area on the
3-4 accumulator 224 in the manner described with
reference to Figure 8.
The condition of the automatic control valves
during an automatic 1-2 upshift, when the manual valve
236 is in the overdrive range position D, is shown in
Figure 16. The 1-2 shift valve 232 responds to an
increased governor pressure in passage 328 and shifts to
the upshift position against the force of the shift valve
spring acting on the lower end of the 1-2 shift valve
232. This allows control pressure to be distributed
from passage 334 to the overdrive servo regulator valve
242 through passage 504. Line pressure~ passes through
that valve to passage 506 which extends to the 1-2
capacity modulator valve 226. Before a 1-2 ratio shift
begins, the 1-2 capacity moduLator; valve and the 1-2
accumulator valve shown at 226 and 2~28, respectively,
assume the positions shown in Figure 16A. After the 1-2
shift begins but before it is completed the 1 2 capacity
modulator valve 226 and the 1-2 accumulator valve 228
assume the position shown in Figure 16B. At that instant
in the shift interval line pressure is distributed to the
1-2 capacity ~modulator valve spool 508 which has two
regulating valve lands S10 and 512. Valve ~spool 508 is
urged in an upward direction by valve spring 511.
35 Pressure i5 fed bac~ to the top to land 510 through the
capacity modulator output~ passage 514 and to the lower
end of the land Sl
The regulated pressure that lS~ produced ln
passage 514 is distributed to the upper end of the
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0 ~ 9
33
cylinder 520 of the 1-2 accumulator valve 228. The
magnitude of the pressure in line 514 is about 5 psi
higher than the pressure on piston 520. The upper side
of the accumulator piston 520 is supplied through the
orifice 522. The pressure in the top of the 1-2
accumulator valve forces the accumulator piston 520 in a
downward direction and assists the accumulator valve
spring 524. Those forces are opposed by the force
produced by the pressure in passage 334 which is applied
to the di,fferential area of the two lands for th
accumulator piston 520. This pressure regulation
continues during intermediate clutch pressure buildup
until the accumulator piston 520 is fully bottomed. When
that occurs, there is no longer any pressure,increase in
lS passage 514 and the capacity modulator valve 226 then
ceases to modulate. The pressures in the 1-2 capacity
modulator valve 226 and the 1-2 accumulator valve 228
- then rlse to the full line pressure value. This
condition is shown in Figure 16C.
The condition of the valves during an automatic
2-3 upshift while the manual valve 236 is in the
overdrive range is shown in Figure 17. Governor pressure
acts on the base of the 2-3 shift valve 258 and moves it
to the upshift position. This allows pressure to pass
from line 331 to passage 528 which extends to the 2-3
backout valve 248. Vent port 526 then is sealed from
passage 528.
Line pressure from passage 528 passes through '
lands 342 and 344 of the 2-3 backout valve 248 and~
through orifice K (see Figures 29 to 31) in the 2-3
backout valve 248, to direct clutch feed passage 530. The
pressure in passage 530 is distributed to the top of the
orifice control valve 250 to cause the latter to move in
' a downward direction. That pressure is applied also to
35 the lower end of the piston for the 2-3 accumulator 252
causing that piston to~stroke in an upward direction, the
effective pressure area on the lower end of the piston
being greater than the effective pressure on the upper
end of the piston. Pressure is forced through orifice K
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34
~ecause of the fact that check valve 532 in the 2-3
backout valve 248 which normally bypasses the orifice K
as well as orifice E, is closed by the pressure in
passage 528.
As explained with reference to Figures 15 and
16, the piston of the 2-3 accumulator 252 was held in a
downward direction by the clutch pressure in the forward
clutch during operation in the first and second ratios.
During the 2-3 upshiEt, however, the accumulator moves up
and the pressure downstream of the orifice K assists the
accumulator spring to force the accumulator 252 upward.
This causes an intensified back pressure flow from the
smaller upper end of the accumulator chamber. This seats
the check valve 316. The only escape for the-flow from
the upper side of the 2-3 accumulator is past the 2-3
capacity modulator valve 558. The modulator valve 554
moves outwardly and regulates that pressure. This
regulation controls the force on the accumulator valve
558 and, therefore, controls the direct clutch apply
20 p~essure during the 2-3 shift interval. When the~
accumulator piston reaches the end of its travel, there
is no longer any flow from the upper end of the
accumulator piston; and direct clutch apply pressure then
rises to the full line pressure.
A shift to the overdrive range during the
automatic upshift mode i5 illustrated in Figure 18. This
requires a release Oe the forward clutch, the exhausting
of the overdrive servo release pressure and the control
of the overdrive servo apply pressure. The direct clutch
30 remains applied, as explained with reference to Figure
17. The 3-4 shift valve 238 moves under the influence of
governor pressure in passage 328 which acts on the land
464 of the 3-4 shift valve assembly. That opens the
forward clutch circuit to restricted exhaust. As the
exhaust port 534 in the 3-4 shift valve assembly is
brought into communication with passage 502, check valve
504 opens and permits flow from the forward clutch to the
` ` passage 502 and to the 3-4 shift valve exhaust port 534.
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~t the same time it blocks distribution of line pressure
from passage 308 to the forward clutch.
The exhausting of pressure from the forward
clutch takes place through the check valve 504 and
through the 3-4 shift valve 238. The flow path for this
exhausting of fluid is designated in Figure 18 by arrows.
The exhaust flow path for the release side of the
overdrive servo 227 takes place as flow from the release
side is passed through passage 332, through the 2-3 shift
valve 234 and then through the 3-4 backout valve 244, the
2-3 backout valve 248 and the check valve 504 to the
exhaust orifice 534 in the 3-4 shift valve 238. The
pressure that acts on the upper end of the 3-4 shuttle
valve land 496 also communicates through the same flow
15 path followed by fluid from the forward clutch 110 to the
3-4 shift valve vent port 534.
The 3-4 shuttle valve 240, which is in the
downward position during operation in the first, second
and third ratios in the overdrive range, moves up under
20 the influence of the spring 500 at the base of the valve
during a ratio change to the fourth ratio position. This
allows the output pressure from the overdrive servo
regulator valve 242 to pass through the shuttle valve 240
to the base on the overdrive servo regulator vaLve 242
25 causing it to cease regulating. Pressure~ then is
distributed through orifice 528 and passage 536.
Pressure from the overdrive servo regulator valve 242 to
the apply side of the overdrive servo 227 passes through
orifice 538 as well as to the upper side of the 3-4
30 accumulator plston 286. This causes the accumulator
piston 286 to move downwardly, thereby causing the
pressure to be less than line pressure during its
movement; The pressure on the underside of the 3-4
accumulator piston 286 is line pressure. The control
35 pressure on the upper side of the 3-4 accumulat~or piston
is applied to the overdrive servo piston and provides a
controlled and cushioned overdrive band engagement to
effect a smooth 3-4 upshift. As soon as the accumulator
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224 is fully stroked, the control pressure rises to full
line pressure.
Prior to the 3-4 upshift sequence, the
overdrive regulaLor valve functions as a regulator valve
and produces i~ the passage 536 a regulated pressure.
This regulatior occurs by the spaced valve lands 540 and
542. The lower end of the land 540 is connected to the
upper end of the overdrive servo regulator valve 242 by
an internal orifice that is shown in dotted lines in
Figure 18. The valve is urged normally downwardly by a
valve spring as indicated. Land 542 is larger than land
540 so that the line pressure supplied to the overdrive
servo regulator valve 242 is modulated to produce a
controlled, reduced pressure in passage 536. This
15 modified servo-apply pressure is available whenever the
1-2 shift valve 232 moves to the upshift position as line
pressura is distributed through the space between valve
lands 372 and 380 of the 1-2 shift valve 232 to the
regulator valve 218.
In Figure 19, there is illustrated the
condition of the valves when the throttle valve is moved
to the full wide-open engine throttle position. At that
time line pressure in passage 294 is distributed directly
through the throttle valve assembly 256 to the throttle
25 pressure passage 400 so that throttle pressure is equal
to line pressure. The output side of the TV limit valve
246 continues to distribute modified TV limit pressure in
passage 418, as previously descri~ed, regardless of the
rise in the magnitude of the pressure in passage 400 to
30 full line pressure which comes through the bore in the
orifice control valve during kickdown. In the Figure 19
condition the high pressure passes through the 3-~4 TV
modulator valve 260 to the base of the 3-4 shift valve
238 causing it to upshift against the opposing influence
of governor pressure. This, as explained previously,
causes release of the overdrive brake servo 227. Line
pressure is distributed also through 3-way check valves
366 and 410 to the upper end of the 2-3 shift valve 234
and to the differential area on the lower two lands 372
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37
and 374 of the 1-2 shift valve 232 as well as to the
lower end of the 3-4 shift valve 238 through the orifice
control v~lve 250. If the speed of the vehicle is
sufficient so that the increased downshift forces on the
2-3 shift 234 valve and the 1-2 shift valve 232 are
cufficient to overcome governor pressure, downshifts will
occur to the second ratio or the first ratio. The
condition shown in Figure 19, however, illustrates merely
a downshift from the fourth ratio to the third ratio.
Figure 20 illustrates the condition of the
valve circuit when the transmission manual valve 236 is
moved to the manual low position at closed throttle while
the vehicle is standing still. The forward clutch 110 is
applied at that time as well as the low-and-r.everse brake
band 172 to permit engine braking. The overrunning
clutch or brake 174 complements the braking ~orque of the
brake band 172 during forward drive operation in manual
low under torque. The 3-4 accumuIator 224 is stroked in
an upward direction since the upper side of the piston
286 is exhausted through passage 292~ and through the
exhaust port in the 1-2 shift valve located between lands
350 and 372 on the 1-2 shift valve 232. Line pressure
acts on the lower ends of the 3-4 shift valve 238, the
1-2 shift valve 232 and on the upper end of the 2-3 shift
25 valve 258 forcing these valves to their downshift
positions. When the 2-3 shift valve 258 is ~so
positioned, line boost pressure is distributed to the~oil
pressure booster valve land 278 through passage 306,~thus~
causing an increase in the regulated circuit pressure
30 during manual low operation in low speed range (the same
is true for the overdrive~range).
Since the engine throttle is at the zero
throttle setting in the Figure 20 addition, ~throttle
pressure is zero as explained previously.
The low servo modulator~valve feed passage 546
is exhausted through the right hand end of the manual
valve 236 so that the low servo modulator valve ~262
cannot distribute line pressure to the apply side of;the
low and reverse servo ~172. Pressure is distributed,
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38
however, to the low servo modulator valve 262 through the
passage 354 which is pressurized by reason of the
connection between passage 348 and passage 354 that is
provided by the 1-2 shift valve 232. The low servo
modulator valve 262 produces a low and reverse modulated
pressure in passage 548 which extends to the low and
reverse brake servo 172.
The low servo modulator valve 262 has a pair of
regulating valve lands 550 and 552. The reverse servo
feed passage 546 is exhausted and ac~s as an exhaust port
for the low servo modulator valve 262. The regulating
valve lands of the low servo modulator valve 262 are
biased in an upward direction, as seen in Figure 20, by a
valve ~pring, thus causing the valve to regulate to
produce a reduced pressure in passage 548, the magnitude
of which is dependent upon the value of the spring for
any given line pressure.
The forward clutch 110 is pressurized by line
pressure distributed through the 3-4 shift valve 238 and
the orifice control valve 250 in the fashion previously
described.
The 1-2 shift valve 232 is locked in the
position shown in Figure 20-by line pressure acting on
the spring end of the valve and to the line pressure
acting on the differential areas of the valve lands.
Similarly the 2-3 shift valve 234 is locked in place by
the full line pressure extending to the upper end of that
valve through the 2-3 TV modulator valve, and to the line
pressure acting on the differential area of the valve~
lands of the 2-3 shift valve.
~ igure 21 shows the condition of the valve
system during first gear engagement in overdrive range at
closed throttle. The forward clutch 110 is applied as
described previously with reference to Figure 8 ~and the
35 2-3 accumulator 252 is fully stroked as shown as is the
3-4 accumulator 224.
Figure 22 shows the condition of the valve
system that exists during operation in second gear at
part throttle in the overdrive range. Figure 22, and
I 1 ~80S~
39
also Figure 21, show the valves in their respective
posltions just after the shift has been completed. The
condition that exists during the shift interval for
Figure 22 was described previousLy with reference to
Figure 16, and Figure 22 should be viewed simultaneously
with Figures 16, 16A, 16B and 16C.
Main line pressure is regulated by the main oil
pressure regulator valve 218 and distributed throughout
the converter and lubrication system, as explained
previouslyO The 3-4 accumulator valve 224 is moved
upwardly by line pressure against the force of the
accumulator valve spring. Since the 2-3 shift valve
still is in the downshift position at thi~ time, line
pressure still is distributed to the boost valve 272 to
cause an increase in the main oil pressure regulator
valve output. 5ince throttle pressure now is available,
as indicated in Figure 22 in the passage 400, an
auxiliary TV pressure force is exerted on the oil
pressure booster valve 262 causing an increase in the
line pressure because of the engine torque that
accompanies the increased throttle pressure at this
instant.
The TV pressure is now sufficient to actuate
the TV modulator valves ~o produce a delayed upshift
signal. The 3-4 backout valve 244 and the 2-3 backout
valve 248 both are shifted to their inoperative positions
as shown since throttle pressure acts on each of the back
valve ends.
Orifice A in the 2-3 backout valve 248 is
30 bypassed through the shifted orifice control valve 250,
passage 312, the 2-3 backout valve and to the forward
clutch 110. Clutch apply pressure continues to hold the
2-3 accumulator valve 252 downward and to hold the 3-4
shuttle valve 240 against its spring force.
The governor pressure acting on the upper end
of the l-2 shift valve 232 is sufficient to move that
valve against the opposing spring and hydraulic forces to
permit a feed of line pressure through the overdrive
servo regulator valve 242 and the 1--2 capacity modulator
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valve 226 to the intermediate clutch 140. The clutch
apply pressure is distributed khrough orifice 522
(orifice F) to the spring end o~ the piston of the 1-2
accumulator valve 228. The accumulator 228, upon
movement in a downward direction, cushions the
application of the intermediate clutch 140. The release
side of the overdrive servo 227 is pressurized because of
the pressure that is distributed to it through passage
331 and the downshifted 2-3 shift valve 234 which
connects passage 331 to passage 332. The overdrive servo
regulator valve 242 continues to supply a modulated
pressure to the apply side of the overdrive servo 227 as
explained previously.
Figure 23 shows the valve condition for third
15 gear operation at 3/4 engine throttle setting in the
overdrive range after the shift has been completed.
Figure 17, in contrast, shows the upshift from the second
ratio to the third ratio in the overdrive range at part
throttle during the shift interval. Under the Figure 23
20 condition, the 3~4 accumulator 224 is forced in an upward
direction so that it can be conditioned for a subsequent
3-4 upshift. TV Iimit pressure from the TV limit valve
246 continues to be supplied to the main oil pressure
booster valve 272 to provide a line pressure boost. The
25 line boost pressure in passage 306 is exhausted through
the exhaust port in the 2-3 shift valve 234 located
between the lower valve land 454 and 456 on the 2-3 shift
valve 234 which results in a reduction in the main oil
pressure regulator valve output.
The 3-4 TV modulator valve 260 assumes a
regulating condition under the influence of the throttle
pressure acting on the lower end of that valve. This
regulating action was explained with reference to Figures
14 and 15.
It will be seen that orifice K is in the fluid
circuit that feeds the direct clutch as pressure is
distributed to the 2-3 backout valve 248 through passage
528. Direct clutch pressure is distributed also at this
instant to the bottom of the piston of the 2-3
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accumulator 252 to cushion the shift to the third ratio
as explained previously.
In Figure 24 there is illustrated the condition
that exists during operation in third gear at 3/4
throttle when the manual valve 236 is in Range 3. The
condition of the valves in Figure 24 is similar to the
condition of the valves in ~igure 23, but the fourth gear
lockou~ is actuated through the passage 554 which
communicates through check valve 410 and through the
orifice control valve 250 to force the 3-4 shift valve
238 in an upward direction. The pressure that exists on
the lower end of the 3-4 shift 238 valve is distributed
through the check valve 410 and locks the shift valve 238
to prevent overdrive from occurring.
The upshift from the third ratio to the
overdrive ra~io is described with reference to Figure 18.
The valve system following the completion of that shift
assumes the condition shown in Figure 25. That is the
condition that exists during normal cruising operation
20 under steady state conditions with the transmission in
the overdrive range. The 3-4 shift valve~ 238 in Figure
has been shifted under the influence ;of governor
pressure to its upshift position. This exhausts the
forward clutch 110 through~the exhaust port 534 in the
25 3~4 shift valve 238. The upper side of ~the 2-3
accumulator piston also is exhausted. Exhaust flow paths
for the forward clutch 110 and the 2-3 accumulator piston
are common and have been;designated by arrows in~Figure
25. Similarly, the overdrive servo rele~ase~ pressure is
30 e~xhausted through;~he 2-3 shift valve, through the 3-4
backout ~alve ~and through the 2-3 backout valve 248 as
indicated also by the arrows in Figure 25 that originate
at the overdrive servo~227 and terminate at the 3-4 shift~
valve 238.
~ The 3-4; shift valve 238 has been moved
downwardly in Figure~25 against the opposing ~orce of the
spring by governor pressure as indicated~thereby opening
the exhaust flow path for the ~release aide of the
overdrive servo 227. Line pressure is supplied, as
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previously described, to the apply side of the overdrive
servo ~27 through the orifice 538 (orifice D). The 3-4
accumulator 224 cushions the shift since the accumulator
piston has been stroked, as indicated, by the apply
pressure for the overdrive servo 227.
Figure 26 shows the condition of the valve
system during reverse drive at initial engagement with
the throttle closed. The initiation of that shift before
it is completed was illustrated in Figure 12 and
described earlier. In the Figure 26 condition the low
servo modulator valve 262 is moved to establish a direct
connection for delivering line pressure to the rever~e
servo feed passage 362. Governor pressure is absent in
this drive mode and throttle pressure th~oughout the
15 circuit is absent because of the closed throttle
condition. Line pressure is distributed directly from
the manual valve 236, which is in the reverse drive
position R, to the check valve 410 and through the
orifice control valve 250 to lock the 3-4 shift valve 238
20 in place. Pressure is distributed also through the check
valve 366 to the various pressure lands on the 1-2 shift
valve 232 which locks it in place. Similarly, the 2-3
shift valve 234 is locked in place by the same control
pressure that is made available to the other shift
25 valve
Figure 27 shows the condition of the valves
during manual low operation with the manual valve in the
No. 1 position at closed throttle when the vehicle is
moving sufficiently fast so that the 2-l downshift point
30 has not been reached and the transmission operates in the
second ratio. The throttle pressure in passage 400 under
these conditions is absent because the engine throttle is
closed. Thus the 2-3 backout valve 248 shifts in a left
hand direction under force of its spring, and the 3-4
35 backout valve 244 shifts in an upward direction under the
influence of its spring force. The forward clutch 110
remains applied under these conditions as it is supplied
with fluid through the 3-4 shift valve 238, the orifice
control valve 250, the 2-3 backout valve 248 and the
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81~
43
orifice A (see Figures 29-31) in the 2-3 backout valve
248. Since the governor pressure is high enough to keép
the 1-2 shift valve 232 in the upshif~ position, line
pressure thus is available to hold ~he intermediake
clutch 140 applied.
Line pressure is distributed from passage 348
and across the 2-3 shift valve 234 to the lower end of
the 3-4 shuttle valve 240 so that the 3-4 shuttle valve
240 is held in an upward position. Line pressure acts on
the overdrive servo regulator valve and holds it in a
nonregulating condition, which is the downward position
shown in Figure 27. The line pressure on the apply side
of the overdirve servo 227 thus is able to apply the
overdrive servo 227. The release side of the overdrive
servo 227 is e~hausted through the flow path provided by
passage 332 as idicated by the arrows. Thls flow path is
define in part by the 2-3 shift valve 234 and the end of
the manual valve 236.
The 2-1 scheduling valve 230 produces a
20 regulated pressure as described with reference to Figure
11. That regulated pressure acts on the base~of the 1-2
shift valve 232. This will cause the 1-2 shift valve 232
to downshift as governor pressure is reduced at lower
road speeds.
In Figure 6, there is illustrated the
relationship between circuit pressure and throttle
pressure during the reverse drive mode, during operation
in first and second ratios, neutral and park modes and
during operation in the third and fourth ratios. During
30 operation in reverse, the reverse line pressure is
effective on the main oil pressure booster valve 272 to
augment the circuit pressure as explained ~Jith reference
to Figure 12. During~operation in the third and fourth
ratios, the q-3 shift v~lve q34, upon moving, causes a
35 cutback without the necessity for providing~an additional
cutback valve as in some conventional control circuits
such as those illustrated in the re~erence citations
mentioned in the beginning of this specification. The
sharp rise in the curves of Figure 6 beginning at a point
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44
corresponding approximately to 25 psi on the abscissa is
due to the fact ~hat the throttle pressure developed by
the throttle valve system is not made available to the
circuit until after the engine throttle advances to the
preselected minimum travel condition which is described
with reference to Figure 13A, 13B and 13C. That TV
characteristic is shown, as mentioned earlier, in Figure
where throttle pressure is plotted against plunger
travel.
The operation of the orifice control valve 250,
which has been described previously, can be understood
more clearly if reference is made to Figures 29, 30 and
31. During idle engagement of the front clutch, the flow
path through the orifice control path is shown in Figure
29 by the arrows. Pressure passes through the
downshifted 3-4 shift valve 238 to the lower end of the
orifice control valve 250 and hence to the 2-3 backout
valve 244 and orifice A to the forward clutch 110.
Throttle pressure during such closed throttle engagement
is removed from the 2-3 backout valve 248 and~that valve
shifts in a left-hand direction as indicated in Figure
29. The dotted lines and the dotted arrow in Figure 29
show the flow path and the valve position during advance
throttle engagement when the throttle pressure is
sufficient to shift the 2-3 backout valve 248 in a
right-hand position.
During a 4-3 torque demand downshift, the
orifice control valve 250 ~functions as shown in Figure
30. It moves in a downward direction under the force of
the orifice control valve spring line pressure feed flow
thus passes through the~ downshifted 3-4 shift valve 238
and through the space between the upper valve lands on
the orifice control valve 250 and through the 2-3 backout
valve 248 and orifice B to the overdrive servo release
35 pressure passage 332 and to the forward clutch llO. The
2-3 backout valve 248 is shifted in a right-hand
direction because OL the presence of throttle pressure on
the left-hand end under a driving condition with torque
applied. ~ ~
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Orifice C in the 2-3 backout valve 250
functions as shown in Figure 31. This is the condition
that exists during a coastiny downshift from overdrive to
the third ratio. The feed passage extends through the
3-4 shift valve 23~ and through the orifice control valve
250, which is shifted downward in Figure 31, and hence
through the 2-3 baclcout valve 248 and orifice C to khe
forward clutch 110. The overdrive servo release circuit
is fed be~ore the flow passes throu~h the orifice C (see
Figure 2A) so that the servo releases quickly.
Engagement o the forward clutch 110 with
advanced engine throttle occurs as previously explained.
Under those conditions the 2-3 backout valve 248 is
shifted in a right-hand direction and pressure i5
distributed through the 2-3 backout valve 248, as
described with reference to Figure 22. The feed passage
in that case is the passage 556 as shown in Figure 22.
Orifice A is bypassed.
Figure 28 is a chart that shows the functions
f the various orifices A, B, C, E and K for the 2-3
backout valve 248. Orific~ K is effective as explained
with reference to Figure 17 during a 2-3~upshift. As
pressure is distributed from passage 528 through the 2-3
backout valve 248 to the feed passage 530 for the direct
clutch 192. Passage 530 communicates with the lower end
of the 2-3 accumuiator 252. Thus the accumulator 252 is
capable of two functions: namely, it cushions direct
clutch application on an automatic 2-3 upshift~and al~so
cushions the front clutch application during the
initiation of the shif~ sequence. It cushions the direct
clutch application since the lower side of the
accumulator piston communicates with the passage 530 as
indicated in Figure 17. This creates a pressure on the
upper side of the piston that is in excess of the
35 magnitude of the pressure on the lower side of the
piston. The pressure Gn the upper side of the piston is
regulated by the 2-3 capacity modulator valve 558 which
comprises a valve spool having valve lands 560 and 562
that ar3 urged in a downward direction by valve springs
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1 1~81~69
46
as indicated. The regulated pressure on the upper side
of the accumulator piston is transmitted through passage
564, as shown in F.igure 17, to the lower side of the land
560 thereby allowing pressure regulation to occur as
fluid flows out of the upper end of the 2-3 accumulator
252. When the accumulator piston reaches the end of its
travel, there no longer is any flow, and direct clutch
apply pressure rises ~o its full value.
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