Control apparatus for automatic transmissions

The automatic transmission control apparatus includes a single dual sequence valve in the hydraulic control circuit which provides timing control functions for engaging the brakes, engaging the brakes and one-way clutch, and operating the dual pistons operatively associated with the clutch, thereby preventing overheat of the friction engagement elements, improving the shifting of the gears through the speed range, and simplifying the hydraulic control circuit arrangement.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to improvements in or to a control apparatus 
for hydraulically operated automatic multiple-speed transmissions for use 
in vehicles. 
2. Description of the Prior Art 
In the conventional hydraulically-controlled automatic transmissions which 
provide three forward gear ratios, for example, an intermediate gear, or 
second speed, is provided by engaging the following elements: one one-way 
clutch F.sub.1, a brake B.sub.2 acting on the clutch F.sub.1, a brake 
B.sub.1 for acting on the engine brake or compensating for insufficient 
capacity of the aforementioned clutch F.sub.1, and a forward clutch 
C.sub.1. Shifting gear ratios from the first to second speed takes place 
by engaging the brake B.sub.2 to enable the transmissions to be 
synchronized with the second speed, and completed by later engaging the 
brake B.sub.1. Shifting down from the third to second speed is completed 
by first engaging the one-way clutch F.sub.1 securely held by the brake 
B.sub.2 and by then engaging the brake B.sub.1. To control the timing at 
which the brake B.sub.1 is to be engaged for upshifting first to second 
and for downshifting third to second. Individual sequence valves are 
provided within the hydraulic control circuit. If the reverse clutch 
C.sub.2 which engages for changing to reverse gears is equipped with a 
dual piston assembly including an inner piston and an outer piston, an 
additional individual sequence valve is required to control the timing for 
the operating sequence of the two pistons. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide an automatic transmission 
control which includes a single dual sequence valve which performs the 
functions of the two or more individual sequence valves mentioned above, 
and which permits a simple construction and less costly hydraulic circuit 
to be manufactured. 
The above object of the present invention can therefore be attained by the 
improvement in or to the automatic transmission control apparatus of the 
type including a multi-speed shifting mechanism having a plurality of 
transmission gear sets and a plurality of friction engaging devices for 
engaging or disengaging members of the gear set so that at least three 
forward speeds and a reverse speed are accomplished with the forward 
speeds including a low speed, a middle speed and a high speed. This type 
of control apparatus also has a hydralic control device for controlling by 
way of engaging or disengaging, the friction engaging devices in 
accordance with input signals to accomplish the forward multi-speeds and 
the reverse speed with the hydralic control device including an oil 
pressure source and a plurality of shift valves for accomplishing the 
speeds by selectively feeding and exhausting oil pressure from the oil 
pressure source to the friction engaging devices in response to input 
signals of the vehicle running conditions including both vehicular speed 
and throttle opening. The inprovement according to the present invention 
includes the fact that the plurality of friction engaging devices have a 
first friction engaging mechanism controllable to engage or disengage so 
as to accomplish the high speed as well as a second friction engaging 
mechanism which is controllable to be engaged or disengaged to accomplish 
the middle speed. A one-way clutch, which is locked at a middle speed and 
released at high speed is included along with a third friction engaging 
mechanism which is connected parallel with the second friction engaging 
mechanism and controllable to be engaged or disengaged to accomplish 
middle speed through the one-way clutch. Furthermore, the hydraulic 
control device has a sequence valve for controlling, by feeding or 
exhausting, a second engaging oil pressure in order to engage or disengage 
the second friction engaging mechanism with the sequence valve including a 
valve element as well as a first oil chamber in which the valve element is 
pushed so as to feed the second engaging oil pressure to the second 
friction engaging mechanism by applying a third engaging oil pressure for 
controlling the third friction engaging mechanism to be either engaged or 
disengaged. A second oil chamber is included in which the valve element is 
pushed so as to release the second friction gauging mechanism upon 
exhausting the second engaging oil pressure by applying the first engaging 
oil pressure for controlling the first friction engaging mechanism to be 
either engaged or disengaged as well as a biasing means for biasing the 
valve elements so as to exhaust the second engaging oil pressure. The 
mechanism is provided so that when the device is shifted up from the low 
speeds to the middle speed, the valve element is actuated towards the 
feeding of the second engaging oil pressure to be second friction engaging 
mechanism when the third engaging oil pressure has arrived at the level 
permitting the third friction engaging mechanism to engage. On the 
downward shifting from the high speed to the middle speed the valve 
element is actuated toward feeding the second engaging oil pressure to the 
second friction engaging mechanism when the first engaging oil pressure 
has arrived at a level permitting the first friction engaging mechanism to 
release and the one-way clutch locks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a schematic view of an example of the overdrive-equipped 
fluid-operated automatic transmissions controlled by the hydraulic control 
apparatus according to the present invention. The automatic transmissions 
include a torque converter with a directly coupling clutch, an overdrive 
unit 2 and a transmission gear unit 3 which provides three forward speeds 
and one reverse speed. The torque converter 1, which is known per se, 
includes a pump 5, a turbine 6 and a stator 7, the pump 5 being connected 
to an engine crankshaft 8, and the turbine 6 being connected to a turbine 
shaft 9. The turbine shaft 9 provides an output shaft for the torque 
converter 1 and also provides an input shaft for the overdrive unit. The 
turbine shaft 9 is connected to a carrier 10 of planetary gears. A direct 
coupling clutch 50 is interposed between the engine crankshaft 8 and 
turbine shaft 9, and is operated for mechanically connecting the 
crankshaft 8 with the turbine shaft 9. A planetary pinion 14 rotatably 
supported by the carrier 10 engages a sun gear 11 and a ring gear 15. An 
overdrive multi-plate clutch C.sub.0 and an overdrive one-way clutch 
F.sub.0 are interposed between the sun gear 11 and the carrier 10, and an 
overdrive multi-plate brake B.sub.0 is interposed beween the sun gear 11 
and a housing or overdrive casing 16 which accommodates the overdrive 
unit. 
The ring gear 15 in the overdrive unit is connected to the input shaft 23 
of the transmission gears 3. A front multi-plate clutch C.sub.1 is 
provided between the input shaft 23 and counter shaft 29, with a reverse 
multi-plate clutch C.sub.2 disposed between the input shaft 23 and sun 
gear shaft 30. A multi-plate brake B.sub.2 is provided by way of the 
multi-plate brake B.sub.1 and one-way clutch F.sub.1 between the sun gear 
shaft 30 and transmission case 18. A sun gear 32 fixed to the sun gear 
shaft 30 forms two trains of planetary gears, one including a carrier 33, 
a planetary pinion carried by the carrier and a ring gear 35 in mesh with 
the pinion, and the other gear train including a carrier 36, a planetary 
pinion 37 carried by the carrier and a ring gear 38 in mesh with the 
pinion. The ring gear 35 in one of the gear trains is connected to the 
counter shaft 29. The carrier 33 in this gear train is linked to the 
carrier 38 in the other gear train. The carriers and ring gear are 
connected to the output shaft 39. A multiplate brake B.sub.3 and a one-way 
clutch F.sub.2 are provided between the carrier 36 in the other gear train 
and the transmission case 18. 
The fluid-operated automatic transmission described above is controlled by 
the hydraulic control which will be described later so that each clutch 
and brake can be engaged or disengaged according to the engine output 
changes and cruising speeds of the automobile, thus providing the 
corresponding shifts of four forward speeds including overdrive speed 
(O/D) or a manually switched shifting to a reverse gear. 
Transmission gear positions and brake operations are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Friction engagement elements 
one- 
one- 
one- 
way way way 
Shift clutch 
clutch 
clutch 
brake 
brake 
brake 
clutch 
clutch 
clutch 
positions C.sub.0 
C.sub.1 
C.sub.2 
B.sub.0 
B.sub.1 
B.sub.3 
B.sub.2 
F.sub.0 
F.sub.2 
F.sub.1 
__________________________________________________________________________ 
Parking (P) o x x x x o x 
Reverse (R) o x o x x o x lock 
lock 
Neutral (N) o x x x x x x 
Forward 
D range 
1st 
o o x x x x x lock 
lock 
over- 
run 
2nd 
o o x x o x o lock 
over- 
lock 
run 
3rd 
o o o x x x o lock 
over- 
over- 
run run 
O.D 
x o o o x x o over- 
over- 
over- 
run run run 
3 range 
1st 
o o x x x x x lock 
lock 
over- 
run 
2nd 
o o x x o x o lock 
over- 
lock 
run 
3rd 
o o o x x x o lock 
over- 
over- 
run run 
2 range 
1st 
o o x x x x x lock 
lock 
over- 
run 
2nd 
o o x x o x o lock 
over- 
lock 
run 
L range o o x x x o x lock 
lock 
over- 
run 
__________________________________________________________________________ 
In the above table, a symbol (O) indicates that the appropriate clutch or 
brake is engaged, and a symbol (X) indicates that the appropriate clutch 
or brake is disengaged. 
FIG. 2 illustrates a preferred embodiment of the fluid circuit in the 
hydraulic control apparatus according to the present invention, which 
permits an automatic or manual shifting of gears by selectively operating 
the clutches C.sub.0, C.sub.1, C.sub.2, and brakes B.sub.0, B.sub.1, 
B.sub.2, B.sub.3 of the automatic transmissions, and the direct-coupling 
clutch 50 of the torque converter. In FIG. 2, the fluid circuit includes 
an oil tank 100, oil pump 101, pressure regulating valve 102, auxiliary 
pressure regulating valve 103, cutback valve 190, throttle valve 200, 
manual valve 210, 1-2 shift valve 220, 2-3 shift valve 230, 3-4 shift 
valve 240, low coast modulator valve 250, intermediate coast modulator 
valve 255, accumulator valves 260, 270, 280, check valve-incorporated flow 
control valves 290, 300, 305, 310, solenoid valves 320, 330, dual sequence 
valve 340, cooler bypass valve 350, lock-up clutch control valve 360, 
lock-up control solenoid valve 370, oil passages between the 
above-mentioned valves and passages for supplying servo-controlled 
pressure oil to the clutches, brakes, and other transmission elements. 
Operating oil which is drawn by the oil pump 101 from the oil tank 100 is 
introduced into the pressure regulating valve 102, which regulates oil to 
a predetermined pressure or line pressure, the regulated oil being 
branched into the oil passage 104 and oil passage 103'. The oil through 
the passage 103' is introduced into the auxiliary pressure regulating 
valve 103, which provides torque converter pressure, lubricating pressure 
and cooler pressure which are regulated to predetermined values depending 
upon the throttle pressures of the throttle valve 200. The manual valve 
210 connected to the oil passage 104 is operatively associated with a 
shift lever at a driver seat. Operating the shift lever manually brings 
the manual valve 210 to positions P, R, N D, 3, 2, and L depending upon 
the positions in the shift lever range. Table 2 summarizes the 
relationships between oil passage 104 and oil passages 105, 106, 109, 110 
at each of the shift lever posiitons. The symbol (O) indicates that the 
oil passage communicates with the appropriate oil passages. 
TABLE 2 
______________________________________ 
P R N D 3 2 L 
______________________________________ 
oil passage 105 o o o o o 
oil passage 106 o o o o 
oil passage 109 o 
oil passage 110 o 
______________________________________ 
The first solenoid valve 320 which controls the 2-3 shift valve 230 has its 
opening 321 closed when it is not energized, causing oil to be pressurized 
in the oil passage 111 communicated through an orifice 322 with the oil 
passage 106. Energizing the valve 230 causes its opening 321 to open, 
allowing the pressurized oil in the passage 111 to be drained from a drain 
port 323. The second solenoid valve 330 which controls the 1-2 shift valve 
220 and 3-4 shift valve 240 has its opening 331 closed when it is not 
energized, causing oil to be pressurized in the oil passage 112 
communicated through an orifice 332 with the oil passage 104. Energizing 
the valve 330 causes its opening 331 to open, allowing the pressurized oil 
in the passage 112 to be drained from a drain port 333. Table 3 shows the 
relationships between the status of the solenoid valves 320 and 330 which 
are energized or deenergized under control of the electronic circuit later 
to be described, and the corresponding shifting to four speeds in the 
automatic transmission. 
TABLE 3 
______________________________________ 
Manual valve 
N D 
shift positions 
gear shifts first second 
third fourth 
1st solenoid valve 
OFF ON ON OFF OFF 
2nd solenoid valve 
OFF ON OFF ON ON 
______________________________________ 
The 1-2 shift valve 220 has a spool 222 backed by a spring 221, and in 
first speed, or low gear, the solenoid valve 330 is energized, allowing 
oil pressure to be removed from the oil passage 112 which sets the spool 
222 to the right position in FIG. 2 under the oil pressure supplied 
through oil passage 113 to the oil chamber 223 at the right end. In second 
speed or gear, the solenoid valve 330 is deenergized, producing oil 
pressure in the oil passage 112 which sets the spool 222 to the left 
position in the figure. In third and fourth speeds, the spool 232 in the 
2-3 shift valve which will be described later is set to the right position 
in the figure, causing oil pressure to be removed from the oil chamber at 
the left end through oil passage 113, which results in setting the spool 
222 to the left position. 
The 2-3 shift valve 230 has a spool 232 backed by a spring 231. In first 
and second speeds, the solenoid valve 320 is energized with no oil 
pressure in the oil passage 111, allowing the spring 231 to move the spool 
232 to the left position. In third and fourth speeds, the solenoid valve 
320 is deenergized, producing oil pressure in the passage 111 which sets 
the spool 232 to the right position. 
The 3-4 shift valve 240 has a spool 242 backed by a spring 241, and in 
first and second gears, a line pressure is drawn into an oil chamber 243 
through oil passage 114, setting the spool 242 to the left position. In 
third and fourth speeds, oil pressure is removed from the oil passage 114; 
in third speed, the solenoid valve 330 is also energized with oil pressure 
removed from oil passage 112, causing the spring 241 to urge the spool 242 
toward the left setting position; and in fourth speed, the solenoid valve 
330 is deenergized with oil pressure developped in the passage 112, 
setting the spool to the right position. 
The throttle valve 200 is actuated in response to the downward or depressed 
stroke of the accelerator pedal, causing the corresponding stroke in the 
indicator valve 201 to take place, which in turn compresses a spring 203 
between the valve 201 and a valve spool 202, producing throttle pressure 
in the oil passage 124. 
With the manual valve 210 at N position, the solenoid valve 330 is 
deenergized and there is oil pressure in the oil passage 112, introducing 
oil pressure into the left-end oil chamber 244 of the 3-4 shift valve 240 
whose spool 242 is set to the right position. In this condition, the 3-4 
shift valve 240 allows a communication between oil passages 104 and 115, 
and the brake B.sub.0 is engaged; the oil passage 120 is communicated to 
the draim port from which the oil pressure is removed, and the clutch 
C.sub.0 is released; and the overdrive unit 3 has its overdrive gears in 
mesh. 
Manually shifting the manual valve 210 to R position produces oil pressure 
in the oil passage 110, introducing oil pressure into the right oil 
chamber 243 of the 3-4 shift valve by way of the 2-3 shift valve 230 with 
the spool 232 set to the left position and through the oil passage 114. 
Thus, for about one second when the manual valve 210 is changed from N to 
R position, the overdrive gears in the overdrive unit 2 are kept in mesh 
and the reverse gears in the planetary gear train 3 are engaged. One 
second after the shifting from N to R, the oil chamber 243 has a rising 
oil pressure, moving the spool 242 to the left position to allow the oil 
passage 104 to communicate with the oil passage 120 which introduces oil 
pressure into the clutch C.sub.0 while removing oil pressure from the oil 
passage 115, so that the brake B.sub.0 is released and the clutch C.sub.0 
is engaged. The gears in the overdrive unit 2 are thus directly coupled to 
the drive shaft, and the planetary gear unit is thus brought to a normal 
reverse gearing. 
For shifting from N to D manually, in first speed, the spool 222 in the 1-2 
shift valve 220 is placed in the right position, removing oil pressure 
from oil passages 116 and 117 linked to the brakes B.sub.1 and B.sub.2 and 
removing oil pressure from the oil passage 118 linked to the brake B.sub.3 
so that the brakes B.sub.1, B.sub.2 and B.sub.3 are released. 
In first speed, the dual sequence valve 340 has a line pressure in its 
right oil chamber 341 which is provided through the oil passage 108 as a 
branch of the oil passage 105, the line pressure causing the spring 345 at 
the back of the spool 347 to be compressed to move the spool 347 to the 
left position. 
When the car reaches a preset speed, the output signal from the computer 
circuit causes the solenoid valve 330 to be deenergized, moving the spool 
222 in the 1-2 shift valve 220 to the left position to allow a line 
pressure from oil passages 105 and 117 to gradually engage the brake 
B.sub.2 through a flow control valve 310 and an accumulator 280, the line 
pressure being also introduced through the oil passage 128 into the left 
oil chamber 346 of the dual sequence valve 340. The sum of the force of 
the spring 345 and the gradually increasing oil pressure in the oil 
chamber 346 reaches a valve greater than the line pressure on a land 342 
until the spool 347 begins to be moved toward the right position. After a 
preset period of time elapses, the spool 347 is then moved to the right 
position. As the solenoid valve 320 is then energized to place the spool 
232 in the 2-3 shift valve 232 in the left position, oil pressure is 
introduced into the brake B.sub.1 through the route of oil passage 
106.fwdarw.2-3 shift valve 230.fwdarw.oil passage 113.fwdarw.intermediate 
coast modulator valve 255.fwdarw.oil passage 124.fwdarw.1-2 shift valve 
220.fwdarw.oil passage 116.fwdarw.dual sequence valve 340.fwdarw.oil 
passage 125, causing the brake B.sub.1 to be engaged. This causes a 
shifting to second speed in which the engine brake becomes effective. At 
this time, the dual sequence valve 340 provides a timing control which 
permits the brake B.sub.1 to be engaged after the transmission is shifted 
to second speed by engaging the brake B.sub.2. 
The shifting to third speed is accomplished in the following manner: the 
output provided by the computer circuit in response to certain throttle 
position and vehicle speed deenergizes the solenoid valve 320, moving the 
spool 232 in the 2-3 shift valve 230 to the right position to allow oil 
pressure to be introduced through oil passage 106 and 121 and flow control 
valve 305 into the clutch C.sub.2 for engagement, while removing oil 
pressure from the oil chamber 223 which causes the spring 221 to lock the 
spool 222 of the 1-2 shift valve 220 in the left position. 
In this third speed, the oil chamber 344 in the dual sequence valve 340, 
which is defined by the land 342 and a land 343 of a predetermined 
diameter greater than the land 342, has oil pressure introduced from the 
oil passage 122 branched from the oil passage 121 so that the spool 347 
can be moved to the left position, allowing the oil passage 125 to 
communicate with the drain port from which oil goes out, thus releasing 
the brake B.sub.1. 
The shifting to fourth speed is done in the manner in which the output 
provided by the computer circuit as above renders the solenoid valve 330 
nonconductive, causing the spool 242 in the 3-4 shift valve to move to the 
right position to allow oil pressure to be removed from oil passage 120 
with oil pressure introduced into oil passage 115, releasing the clutch 
C.sub.0 and engaging the brake B.sub.0. 
The downshifting from fourth to third speed is accomplished in the reverse 
sequence to that of the upshifting from third to fourth speed as discussed 
above, that is, by energizing the solenoid valve 330 so that the spool 242 
in the 3-4 shift valve 240 is moved to the right position, allowing oil 
pressure to be removed from oil passage 115 while introducing oil pressure 
into oil passage 120, thereby releasing the brake B.sub.0 and engaging the 
clutch C.sub.0. For the downshifting from third to second speed, 
energizing the solenoid valve 320 causes the spool 232 in the 2-3 shift 
valve 230 to be moved to the left position, allowing oil pressure to be 
removed from the oil passage 121 for releasing the clutch C.sub.2, 
followed by engaging the one-way clutch F.sub.1. When the one-way clutch 
F.sub.1 has completely been engaged, oil pressure is removed from the oil 
passage branch 122 of the oil passage 121 as well as from the oil chamber 
344 linked to the passage 122, causing the spool 347 in the dual sequence 
valve 340 to be moved to the right position against the oil pressure in 
the chamber 346 introduced from oil passage 128 and the oil pressure 
applied on the land 342 by the resilient action of the spring 345. This 
causes the oil passage 125 to be communicated to the oil passage 116, 
engaging the brake B.sub.1. In this case, the dual sequence valve 340 
provides a timing control for engaging the one-way clutch F.sub.1 and 
engaging the brake B.sub.1. 
With the manual valve 210 at position 3, the shifting to first, second and 
third speeds is done in the same manner as in the D position as earlier 
described, but the shifting to a fourth speed does not take place because 
a line pressure, which is introduced in the right chamber 243 of the 3-4 
shift valve from the oil passages 106 and 114, causes the spool 242 to be 
locked in the left position. If the manual valve 210 is manually operated 
to shift from D to 3 while the car is running in fourth gear with the 
valve 210 at D position, the downshifting to third speed takes place 
immediately. 
When the manual valve 210 is placed at position 2, a shifting to first 
speed takes place in the same manner as at D position. In second speed, 
oil pressure from oil passages 106 and 116 causes the brake B.sub.1 to be 
engaged, making the engine brake work effectively. If manual shifting to 
position 2 takes place when the car is cruising in third gear, the 
computer circuit responds to a vehicle-speed loss down to a certain value, 
providing output which energizes the solenoid valve 320 to cause a 
downshifting from 3 to 2 to take place. 
When the manual valve 210 is shifted to L position, oil pressure is 
introduced into the oil passage 109, producing a line pressure in the 
right oil chamber 233 of the 2-3 shift valve 230 causing the spool 232 to 
be locked in the left position and thus immediately causing a downshift 
from 3 to 2 to take place. The downshifting from 2 to 1 takes place when 
output provided by the computer circuit in response to a certain vehicle 
speed loss disables the solenoid valve 330 to be nonconductive. At the 
same time, the oil pressure in the oil passage 109 is introduced through 
oil passage 107, low coast modulator valve 250, and oil passages 123 and 
118 into the brake B.sub.3 for engagement. 
The following describes the electronic circuit or computer shown in FIG. 3 
which responds to changes in the vehicle running condition for controlling 
the operation of the first and second solenoid valves 320 and 330 as 
defined in the Table 3. 
The electronics circuit generally includes a power supply circuit 420, and 
a computer circuit 400 which includes vehicle-speed and throttle-position 
sensing devices as an input section and a drive output section for the 
solenoid valves 320 and 330, including other intermediate circuit elements 
to later be described in detail. A switch 421 in the power supply circuit 
420 is connected to an external battery (not shown) and is also connected 
to a position switch 422 on a manual lever. The position switch 422 is 
selectively connected through a lead wire 520 to 0, 3, 2, L positioning 
mechanisms, and through a lead wire 521 to a constant voltage power supply 
423 which provides constant voltage through a lead wire 523 to the circuit 
elements in the computer circuit 400. The computer circuit arrangement 
includes vehicle-speed sensor 401, reshaper 402, D-A (digital-analog) 
converter 403, throttle-position switch 413, throttle-position voltage 
generator 414, 1-2 shift discriminator 404, 2-3 shift discriminator 406, 
3-4 shift discriminator 408, hysteresis circuits 405, 407, 409, valve 
control circuit 410 for solenoid valve 320, valve control circuit 412 for 
solenoid valve 330, N-R shift signal generator 415, timer 411, amplifiers 
416, 417, and solenoid valves 320, 330. The vehicle-speed sensor 401 
provides a sine wave signal in response to a vehicle speed, and the signal 
is fed to the reshaper 402 which reshapes it to a positive rectangular 
signal, which is applied to the D-A converter 403. The D-A converter 
provides a d.c. voltage signal whose magnitude depends upon the vehicle 
speed. The throttle position switch 413 detects engine loads, and includes 
a variable resistance which varies with the throttle positions. The switch 
provides an output signal which represents a throttle position, and the 
signal is delivered to the throttle-position voltage generator 414 which 
supplies the corresponding d.c. voltage. This voltage is applied to the 
1-2 shift discriminator 404, 2-3 shift discriminator 406, and 3-4 shift 
discriminator 408. Each of the discriminators includes a differential 
amplifier, for example, which compares a vehicle-speed voltage signal and 
a throttle-position voltage signal to determine the 1-2 shift, 2-3 shift 
and 3-4 shift. The hysteresis circuits 405, 407 and 409 provide the 
respective downshifting conditions for the 2-1 shift, 3-2 shift and 4-3 
shift, and permit the respective downshifting to be operated at a slightly 
lower shifting car speed than the corresponding shifting car speed for the 
upshifting course, thereby preventing a hunting in the gear shift range. 
The opening control circuit 410 for solenoid valve 320 provides output 
signal "0" (OFF) and output signal "1" (ON) depending on the output of the 
2-3 shift discriminator. The output of the circuit 410, which is amplified 
by the amplifier 416, controls the solenoid valve 320 for opening or 
closing depending on the output level received. The opening control 
circuit 412 for solenoid valve 330 delivers output signal "0" and output 
signal "1" depending on the output of the 1-2 shift discriminator 404, the 
output of the 3-4 shift discriminator 408, and the output of the N-R shift 
signal generator which is fed through the timer 411 into the circuit 412. 
The output of the circuit 412 is amplified by the amplifier 417 for 
controlling the solenoid valve 330 for opening or closing. 
As readily understood from the foregoing description, the automatic 
transmission control apparatus according to the invention includes a 
single dual sequence valve 340 which provides a timing control for the 
operation of the brakes B.sub.1, B.sub.2 and oneway clutch F.sub.1, 
thereby controlling the timing of upshifting from first to second speed 
and downshifting from third to second speed. 
The following description concerns a varied form of the apparatus described 
heretobefore, as shown in FIG. 4. 
If a reverse multi-plate clutch C.sub.2 within the automatic transmissions 
gear unit 3 is equipped with an inner piston I and an outer piston O which 
provide hydraulic servo functions, it is necessary to provide means to 
control the timing of the operation of the two pistons to permit a smooth 
gear engagement for shifting to reverse. In order to meet the above needs, 
therefore, the hydraulic circuit of the earlier embodiment includes an 
additional hydraulic circuit in which an oil passage 126 is provided as a 
branch from the oil passage 110, the branch 126 being linked to an oil 
passage 127 through a dual sequence valve 540 and to an outer piston O for 
the clutch C.sub.2 linked to the above passage 127. In this varied 
embodiment, when the spool 547 of the dual sequence valve 540 is set to 
the left position in FIG. 4, the oil passage 126 is allowed to communicate 
with the oil passage 127, causing the outer piston O to operate. Setting 
the spool 547 to the right position allows the oil passage 127 to 
communicate to the drain port, thus preventing the outer piston O from 
operation. A flow control valve 305 is interposed between an oil passage 
121 and an inner piston I for the clutch C.sub.2. 
The automatic transmission control apparatus according to the varied form 
of the invention provides additional functions, as follows. Manually 
shifting N to R first causes oil pressure to be routed through oil passage 
110, 2-3 shift valve 230, oil passage 121 and flow control valve 305 into 
the inner piston I. Then, the oil pressure being introduced through oil 
passage 122 into the oil chamber 344 of the dual sequence valve 540 in 
rising. The increasing oil pressure causes the spool 547 in the valve 540 
to be moved toward the left position, allowing the oil passages 126 and 
127 to be communicated so that the outer piston O can be operated. As seen 
from the above, the dual sequence valve 540 can also provide timing 
control functions for operating the inner piston I and outer piston O for 
the clutch C.sub.2. 
FIG. 5 is a further embodiment of the dual sequence valve generally shown 
by 640, the arrangement comprising a spool 642 backed by a spring 641, a 
right oil chamber 643 linked to the oil passage 122, another spool 644 
having a land of greater diameter than the land of the spool 642 and 
disposed to make contact with the spool 642, an oil chamber 645 interposed 
between the spools 642 and 644 and linked to the oil passage 128, a left 
oil chamber 646 linked to a branch 129 of the oil passage 126, an oil 
chamber 647 between the lands on the spool 642, the oil chamber 647 
allowing the oil passages 126 and 127 to be linked, and an oil chamber 648 
allowing a link between the oil passages 116 and 125. 
In accordance with the dual sequence valve 640, the upshifting from first 
to second speed is achieved such that that after the brakes B.sub.2 have 
been engaged, oil pressure is introduced through the oil passage 128 into 
the oil chamber 645, and as it is gradually rising, the spool 642 is 
forced to be brought nearer to the right positions against the action of 
the spring 641, allowing the oil passages 116 and 125 to communicate with 
each other and thus engaging the brake B.sub.1. The downshifting from 
third to second speed is done in this way, that is, after engaging the 
one-way clutch F.sub.1 securely held by the brake B.sub.1, the spool 642, 
which has been held in the left position by the component of the force of 
the C.sub.2 inner piston pressure in the oil chamber 643 introduced 
through the third-speed oil passage 122, and the force of the spring 641, 
is then brought to the right position as the C.sub.2 inner piston pressure 
in the chamber 643 is reduced, allowing the oil passages 116 and 125 to 
communicate and thus engaging the brake B.sub.1. In the case of the 
reverse clutch C.sub.2 provided with an inner piston I and an outer piston 
O, the shifting of N to R takes place in the following manner. After the 
inner piston I linked to the oil passage 121 has completed its operation, 
oil pressure is introduced into the oil chamber 643 through the oil 
passage 122, and as it is gradually rising, the component of the resilient 
force of the spring 641 and the force of the oil pressure in the chamber 
643 overcome the force of the oil pressure in the oil chamber 646, 
permitting the spools 642 and 644 to be moved to the left position. The 
oil passages 126 and 127 are thus allowed to communicate with each other, 
causing the outer piston O to operate. 
FIG. 6 is a further preferred embodiment of the dual sequence valve which 
is generally shown by 740. The arrangement of the valve 740 comprises a 
spool 742 backed by a spring 741, a small diameter plunger 743 on the left 
side of the spool 742, an oil chamber 744 linked to the oil passage 122 
and interposed between the spool 742 and the plunger 743, a right oil 
chamber 745 linked to the oil passage 128, a left oil chamber 746 linked 
to a branch 130 from the oil passage 116, an oil chamber 747 between the 
lands on the spool 742 and allowing a communication between the oil 
passages 116 and 125, and an oil chamber 748 allowing a communication 
between the oil passages 126' and 127. 
In accordance with the dual sequence valve 740, for shifting of first to 
second speed, the oil pressure which has made the brakes B.sub.2 engaged 
is then introduced through the oil passage 128 into the left oil chamber 
745. The oil pressure gradually rising in the chamber 745 causes the spool 
742 and plunger 743 to be moved to the left against the component of the 
resilient force of the spring 741 and the force of the oil pressure in the 
chamber 746 introduced through the oil passage 130. The oil passages 116 
and 125 are thus communicated, allowing the brakes B.sub.1 to be engaged. 
For 3-2 downshifting, after the one-way clutch F.sub.1 has been engaged, 
the spool 742, which has been held in the right position by the C.sub.2 
clutch pressure in the oil chamber 744 introduced through the third-speed 
oil passage 122, is then brought to the left position as the C.sub.2 
clutch pressure is decreasing, allowing the oil passage 116 and 125 to be 
communicated and thus engaging the brakes B.sub.1. For the reverse clutch 
C.sub.2 which is equipped with an inner piston I and an outer piston O, 
upon completion of the inner piston operation, the cooperative action of 
the oil pressure in the oil chamber 744 introduced through the oil passage 
122 and the spring 741 causes the spool 742 to be moved to the right 
position, communicating between the oil passages 126' and 127 and thus 
making the outer piston O operative. 
The various embodiments of the control apparatus according to the present 
invention have been shown and described, and as it is readily understood 
from the foregoing description, a single dual sequence valve can perform 
the multiple timing control functions which have heretofore been made 
possible by using the two or more sequence valves. It is therefore 
advantageously possible to simplify the hydraulic circuit arrangement, and 
therefore reduce its manufacturing costs. 
Although the present invention has been described with reference to the 
various embodiments thereof, it should be understood that various changes 
and modifications may be made within the spirit and scope of the 
invention.