Abstract: A shift control apparatus includes an automatic transmission provided with a first friction-engagement element and a second friction-engagement element; and a friction-engagement element control section configured to control the first and second friction-engagement elements. The friction-engagement element control section includes a target-value setting section configured to set a first target differential speed; a first control section configured to bring a rotational speed difference of the first friction-engagement element gradually close to the first target differential speed; and a second control section. The second control section includes a torque-capacity calculating section configured to calculate a total transfer-torque capacity, and a distribution ratio setting section configured to set a distribution ratio between transfer-torque capacities of the first and second friction-engagement elements.

Abstract: A hydraulic control system for an automatic transmission includes a planetary gear system having a plurality of clutch elements that alters the torque ratio of the transmission. The hydraulic control system includes a line pressure control device for regulating a variable hydraulic line pressure from a maximum line pressure to a fixed fluid line pressure that is lower than the maximum line pressure when an overdrive clutch is applied in a high gear.

Abstract: An automatic transmission comprising a plurality of planetary gears disposed between an input shaft and an output shaft and having a plurality of rotational elements, a plurality of frictional elements selectively engaged and released for controlling rotations and connections of the plurality of rotational elements in accordance with instructions so as to realize a plurality of gear positions, rotational speed detecting means for detecting a rotational speed of a predetermined one of the plurality of rotational elements, other than the input shaft and the output shaft, and frictional element release means for releasing all of the plurality of frictional elements when it is judged that the rotational speed of the predetermined one of the plurality of rotational elements is higher than a predetermined rotational speed.

Abstract: At the time of a failure in the second group of engagement devices, the manner of input of oil pressures to a fail-safe valve group is changed via a priority degree switching valve on the basis of the state of engagement of engagement devices of the first group in such a manner that the predetermined degrees of priority for the supply of one of oil pressures PC4, PB1 output from linear solenoid valves SL4, SL5 to a corresponding one of a clutch C4 and a brake B1 via the fail-safe valve group are changed so as to avoid an event that the fail-safe gear stage established in order to prevent the occurrence of interlock of the automatic transmission involves a downshift of two or more stages from the speed change stage maintained immediately prior to the occurrence of the failure. Therefore, it is possible to prevent the occurrence of an uncomfortable behavior of the vehicle caused by the shift to the fail-safe gear stage.

Abstract: At a first forward speed, the oil passage in a relay valve is switched to control the torque capacity of a lock-up clutch using a linear solenoid valve that controls the engagement pressure of a clutch that is engaged at each of fifth to eighth forward speeds. At each of second to eighth forward speeds, the oil passage in another relay valve is switched to control the torque capacity of the lock-up clutch using a linear solenoid valve that controls the engagement pressure of a brake that is engaged at the first forward speed.

Abstract: A transmission for a vehicle includes a first gear set and a second gear set. A first plurality of elements are operable in an applied state and a released state and a second plurality of elements are operable in an applied state and a released state. A controller toggles the first and second plurality of elements between the applied state and the released state to achieve a desired gear ratio. The controller times entry of at least one of the first and second plurality of elements into: the released state with entry of at least another of the first and second plurality of elements into the applied state by controlling a hold pressure applied to the at least one element entering the released state. The controller determines the hold pressure by referencing current operating conditions of the transmission in a lookup table stored in a memory of the controller.

Abstract: A hydraulic control apparatus of an automatic transmission. The hydraulic control apparatus of the automatic transmission has a hydraulic servo for controlling an engaging state of a clutch C-1 on the basis of supplied oil pressure, a linear solenoid valve for C-1 for outputting signal pressure by adjusting the oil pressure, a control valve for outputting control pressure provided by adjusting line pressure PL on the basis of the signal pressure of the linear solenoid valve for C-1, and a C-1 apply relay valve for inputting, selectively switching and outputting the control pressure and the line pressure PL to the hydraulic servo. An orifice for regulating the flow rate of the oil is arranged in an oil path g for inputting the line pressure PL to this C-1 apply relay valve.

Abstract: A hydraulic pressure control apparatus for an automatic transmission having plural engaging elements (a first engaging element and a second engaging element) includes plural control valves (a first control valve and a second control valve) controlling each engaging element by supplying controlled hydraulic pressure as output pressure, plural shift valves for switching an oil passage for the line pressure, a fail valve closing an input port and a fail output port thereof while the output pressure is supplied from the second control valve; wherein, once the line pressure is supplied to the control valve through a supply port and a drain port thereof, it outputs the line pressure from as output pressure, and once the line pressure is supplied to the fail valve through the input port and a release port thereof, it outputs the line pressure as output pressure.

Abstract: Whenever a 4 to 3 shift condition is satisfied during a 3 to 4 upshift, 4 to 3 shifting is started before the 3 to 4 shifting is finished. The 4 to 3 shifting is executed according to a predetermined hydraulic control pattern. Therefore, responsiveness in shifting is enhanced.

Abstract: An automatic transmission for a vehicle includes an input shaft, an output shaft, a first and second plurality of gears, and a series of engagement elements. The series of engagement elements includes at least one overrunning engagement element in mechanical communication with the second plurality of gears. A controller is operable to disengage a first engagement element associated with a first one of the first plurality of gears and apply a second engagement element associated with a second one of the first plurality of gears to achieve a speed change of the first plurality of gears. The controller is adapted to disengage one of the overrunning engagement elements from engagement with one of the second plurality of gears within a range of 20 to 120 milliseconds after the speed change of the first plurality of gears to accomplish a gear shift of the transmission.

Abstract: A transmission includes an input shaft, an output shaft, a first plurality of gears, a second plurality of gears, and a series of engagement elements operable between an engaged position and a disengaged position. A controller is further provided to selectively toggle the series of engagement elements between the engaged position and the disengaged position to selectively couple one of the first plurality of gears or one of the second plurality of gears to the input shaft and the output shaft. The series of engagement elements sequentially couples the first plurality of gears to the input shaft and the output shaft during operation of the transmission and selectively couples one of the first plurality of gears or the second plurality of gears to the input shaft and the output shaft during a downshift operation of the transmission.

Abstract: A control method for an automatic transmission is capable of quickly determining whether gear shifting is permissive. The control method varies the command value input to an engaging-side electromagnetic valve that adjusts a hydraulic pressure applied to a frictional element to be engaged in a target gear in a specific time period, then determines a time variation in another time period of the hydraulic pressure applied to the frictional element that is adjusted by the engaging-side electromagnetic valve according to the input command value and detected by a detecting means. Determination of whether gear shifting is permissive or not on the basis of the time variation is thus determined.

Abstract: According to an aspect of the present invention, an automatic transmission includes plural friction engaging elements configures plural shift ranges based on combinations of each friction engaging element being in engaging or disengaging condition, a controlling unit for controlling the friction engaging elements to be in engaging or disengaging condition by controlling a hydraulic pressure applied.

Abstract: A shift control method for an automatic transmission having a primary shift portion and a secondary shift portion is provided that comprises: starting, if a shift signal is output, a shift in the secondary shift portion, and then starting a shift in the primary shift portion; performing feedback control of duty ratios of friction element solenoids for the primary shift portion with a goal of approaching a change rate of a difference between an input speed and an output speed of the primary shift portion to a first target speed change rate, and simultaneously performing feedback control of duty ratios of friction element solenoids for the secondary shift portion with a goal of approaching a change rate of a turbine speed to a second target speed change rate; and completing the shift in the primary shift portion, and then completing the shift in the secondary shift portion.

Abstract: An oil pressure control device, which changes a range of a vehicle transmission includes: a pressure adjusting device that engages or releases forward and reverse frictional-engagement devices by adjusting an oil pressure supply, a sensor that detects a range selected by a vehicle driver, and a controller that controls the clutch pressure adjusting device based on a signal from the sensor. When the stop range is selected after selecting the reverse (forward) range, a forward (reverse) range is selected. After supplying an initial oil pressure to the forward (reverse) frictional-engagement device, the pressure adjusting device is controlled so that the pressure decreases from the initial oil pressure to a predetermined oil pressure. Subsequently, the oil pressure is initially increased at a small increase rate from the predetermined oil pressure. After a predetermined time period has elapsed, the pressure adjusting device increases the oil pressure at a large increase rate.

Abstract: The method for testing the function of an electrohydraulically controlled automatic transmission upon a testing stand by simulation of a vehicle operation provides that the output shaft of the transmission be connected with a stationary torque-measuring hub and be blocked thereby; the shifting elements existing in the transmission are tested when the output shaft is blocked with an input rotational speed which is precisely sufficient to supply with hydraulic pressure the pressure setting members for the shifting elements. As characteristic quantity can be used the setting member current at which the shifting element slips or at which the slip tends toward zero when the shifting element closes.

Abstract: An automatic transmission control device controls multiple speed changes in which shifting from first speed to second speed occurs during shifting from second speed to first speed. The control device includes a shift lever position sensor, an ECT_ECU, and an AT linear solenoid. The ECT_ECU includes a circuit that detects multiple speed changes; a circuit that controls the AT linear solenoid such that an engagement pressure of an engaged first speed engine brake friction element sweeps down when multiple speed changes are detected; and a circuit that commands a shift to second speed once a predetermined time has passed since the detection of multiple speed changes assuming that the engagement pressure of the first speed engine brake friction element has sufficiently swept down.

Abstract: A method for control of a transmission of a vehicle, especially of an automatic transmission or an automated manual mechanical transmission with hydraulically actuatable shifting elements is described. A speed signal (n_ab_ist, n_t_ist) of the output train with precalculatable time curve (n_ab_soll, n_t_soll) is determined and for adjustment of a nominal filling of the shifting elements an interference signal (P1, P2, P3, P4, PF1, PF2, PF3, PF4) is applied. In case of a untolerable divergence of the speed signal (n_ab_ist, n_t_ist) of the output train from its precalculated curve, a divergence from the nominal filling of the shifting element is detected, the information being processed for control of the shifting elements.

Abstract: An automatic transmission control device controls multiple speed changes in which shifting from first speed to second speed occurs during shifting from second speed to first speed. The control device includes a shift lever position sensor, an ECT_ECU, and an AT linear solenoid. The ECT_ECU includes a circuit that detects multiple speed changes; a circuit that controls the AT linear solenoid such that an engagement pressure of an engaged first speed engine brake friction element sweeps down when multiple speed changes are detected; and a circuit that commands a shift to second speed once a predetermined time has passed since the detection of multiple speed changes assuming that the engagement pressure of the first speed engine brake friction element has sufficiently swept down.

Abstract: A hydraulic control unit including a hydraulic servo for engaging and disengaging each friction engagement element, hydraulic pressure supply device for supplying hydraulic pressure to a hydraulic servo of a predetermined friction engagement element selected according to a gearshift position to be achieved, failure detection device for detecting a failure has occurred in the hydraulic pressure supply device, and fail-safe device for preventing interlock that occurs due to a plurality of friction engagement elements being engaged, and also prevents a gearshift from a high-speed position to a low-speed position, when the failure detection device detects that a failure has occurred.

Abstract: A hydraulic control apparatus includes a linear solenoid valve for outputting modulated pressure in response to electric current applied to the linear solenoid valve, a plurality of control valves outputting control pressure in response to the modulated pressure introduced from the linear solenoid valve, a shift valve for switching between the control valves to which is to be introduced the modulated pressure in response to hydraulic pressure supplied to the shift valve, and an ON-OFF solenoid valve for switching the supply of the hydraulic pressure to the shift valve in response to electric current applied to the ON-OFF solenoid valve.

Abstract: This invention provides a hydraulic control system for controlling a power train including four clutches and two brakes, wherein a first pressure controlled by a first solenoid valve is selectively supplied to two clutches of the power train under control of a first switch valve, a second pressure controlled by a second control valve is selectively supplied to another clutch and a first brake of the power train under control of a second switch valve, hydraulic pressure from a port of a manual valve is supplied to yet another clutch via a control valve, hydraulic pressure from another port of the manual valve is supplied to a second brake via another control valve, and the two control valves are controlled by a third solenoid valve.

Abstract: A powertrain has an electro-hydraulic control mechanism that provides for the establishment of six forward speeds, a neutral condition and a reverse speed. The control system also permits operation in the fifth forward range if electrical power is discontinued when the transmission is operating in the third range or higher, and permits operation in the third range if the transmission is operating in the second range or lower when an electrical power discontinuance occurs. If an electric disconnect occurs, the reverse drive is available, neutral is available, and third forward drive is available from the reverse and neutral conditions. The drive-home functions described are provided through the use of a multiplex valve, default valve and a pair of solenoid valves. The multiplex valve and default valve also permit the controlling of two mutually exclusive torque transmitting devices through the use of a single trim valve.

Abstract: Between a control unit such as a control unit for an automatic transmission and a mounting bracket, there is provided an interconnection integrated insulating sheet including a plurality of buried interconnection patterns for connecting the control unit with associated components, such as oil sensors and connectors for solenoid valves, mounted on the bracket. The control unit is mounted on the insulating sheet and enclosed by a protective cover mounted on the insulating sheet. The insulating sheet is overlapped on the mounting bracket and the mounting bracket is fixed to a control valve of an automatic transmission together with the insulating sheet.

Abstract: In a replacement gear shift effected by engagement of a first friction engagement element by increasing a first fluid pressure and instead by disengagement of a second friction engagement element by decreasing a second fluid pressure, a shift control apparatus forcibly increases the first fluid pressure at a gradual rate to prevent an undesired shift shock if the inertia phase does not end within a predetermined time.

Abstract: A hydraulic control system includes switching mechanisms for receiving as a signal pressure a hydraulic pressure which is output from each shifting mechanism when all units of the shifting mechanisms are caused to output a hydraulic pressure, and being responsive to the reception of the signal pressure to be switched to a predetermined state for blocking a hydraulic-pressure supply path to specific hydraulic servos, thereby achieving a specific speed out of a plurality of speeds; and supply switching mechanisms provided in a hydraulic-pressure supply path to a hydraulic servo which is not included in the specific hydraulic servos, for switching between supply and cut-off of the hydraulic pressure to the hydraulic servo so as to assure two speeds in the event of the signal failure in a hydraulic control system for individually controlling engaging elements in an automatic transmission by using electric signals.

Abstract: An output bearing assembly of a transmission includes a housing, and a pair of bearings. At least one speedometer sensor is mounted between the bearings. The arrangement allows the output bearings to be spaced axially by a relatively great distance.

Abstract: A hydraulic control system for an automotive automatic transmissions includes a pressure regulator for regulating hydraulic pressure, a pressure reducer having a reducing valve for reducing hydraulic pressure, a shift controller having a manual valve cooperating with a shift selector lever and connected to a plurality of range pressure lines, a pressure controller comprising first, second and third solenoid valves for controlling control pressure reduced by the reducing valve, and first, second and third pressure control valves for controlling hydraulic pressure supplied from the manual valve, the first, second and third pressure control valves being independently controlled by control pressure supplied from the first, second and third solenoid valves, respectively, a switching controller comprising a first switch valve for supplying hydraulic pressure from the first pressure control valve to one of first and second switching lines and a second switch valve for supplying hydraulic pressure from the third pres

Abstract: To reliably establish a shift in a hydraulic pressure control device for an automatic transmission in which a control valve applies a control pressure, by way of a shift valve, to a plurality of friction engaging elements, the hydraulic pressure control device is designed to establish an intermediate shift pattern. The hydraulic pressure control device includes an electronic control unit that establishes shift pattern 3 to produce the second and third gear stages and shift pattern 5 to produce the third, fourth and fifth gear stages in which ON-OFF solenoid valves under energization are combined to produce both the second and third gear stages.

Abstract: A hydraulic control apparatus of automatic transmission comprising a hydraulic pressure source, hydraulic paths, hydraulic servos for operating friction elements which are coupled with the hydraulic source and the hydraulic paths, a control device arranged on the hydraulic paths for operating engagement release through supply/removal of hydraulic pressure to the hydraulic servos and valves which are arranged on the hydraulic path for cutting off hydraulic pressure from the hydraulic pressure source to the hydraulic servo with hydraulic pressure in the downstream side of the control means as signal pressure.

Abstract: A control apparatus for a transmission having a first gear ratio, a second gear ratio, and an output shaft is disclosed. The apparatus includes an actuator assembly which disengages the first gear ratio from the output shaft and engages the second gear ratio to the output shaft in response to an upshift signal. The apparatus further includes a memory device which stores a conservative upshift point and an aggressive upshift point. The apparatus yet further includes a controller operable to read the aggressive shift point and the conservative shift point from the memory device. The controller is further operable to determine if the transmission is operating in a conservative mode of operation or operating in an aggressive mode of operation.

Abstract: A method for determining parameters of an electrohydraulically controlled automatic transmission (4) by, on a final test bench, successively initiating transmission gearshifts. During gear changes the parameters of the automatic transmission are determined from measuring values transmission input/transmission output speeds (10, 12) and transmission input/transmission output moments (11, 13).

Abstract: Hydraulic pressure regulated by a first pressure control valve is supplied to an electromagnetic changeover valve. The electromagnetic changeover valve changes over the hydraulic pressure between a low & reverse passage communicating with a low & reverse brake and a high clutch passage communicating with a high clutch, thereby a simultaneous engagement of the low & reverse brake and the high clutch can be avoided and further the simplification of the hydraulic control apparatus of an automatic transmission can be realized.

Abstract: An automatic control system for a multiple ratio transmission includes an electronically controlled variable orifice configuration within a discharge circuit for a downshift control system from a high speed ratio to an intermediate speed ratio. The variable orifice configuration divides the discharge circuit into an upstream part communicating with an accumulator chamber of an accumulator and an intermediate brake release pressure chamber defined by a double acting piston of an intermediate ratio brake servo, and a downstream part communicating with a high speed ratio clutch. A calibrated flow control orifice is disposed in the discharge circuit to control discharge flow of oil from said downstream part. A transmission controller reduces the variable orifice configuration to provide a reduced orifice size during inertia phase of the downshift.

Abstract: Measurement is made of a time of lapse from the time at which the hydraulic pressure of the hydraulic engaging element on engaging side to be engaged at the time of speed changing has increased to a predetermined pressure. Even if an input and output speed ratio of the transmission does not fall within a predetermined range, i.e., a range between YG(N+1)L and YG(N+1)H, which serves as a basis for judging whether the speed changing has been completed or not, a processing of speed change completion is performed when the above-described value TMSTB-TM has reached a predetermined value YTMUP4, to boost the ON pressure to the line pressure.

Abstract: A system for controlling gear (gear ratio) shifting in an automatic transmission mounted on a vehicle, including a shift control means for generating a shift command to upshift from one gear (gear ratio) currently established to a next gear (gear ratio) by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear (gear ratio) so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear (gear ratio) to be shifted to.

Abstract: A control apparatus executes appropriate speed change control under any operating conditions encountered during an up-shift by change-over, without requiring an increase in control logic. Engagement side hydraulic pressure is swept up as a result of an arithmetic operation in torque phase speed change control. Disengagement side hydraulic pressure is calculated by initial speed change control, dependent on the engagement side hydraulic pressure. The engagement side hydraulic pressure is directly controlled and the disengagement side hydraulic pressure is indirectly controlled, i.e. responsive to the engagement side control. Consequently, the same control scheme can be executed regardless of power-on state or power-off state and regardless of vehicle operating conditions.

Abstract: A hydraulic control system for an automatic transmission including a plurality of frictional elements associated with respective transmission speeds. The hydraulic control system includes a hydraulic fluid source, a line pressure/reducing pressure producer, a shift controller for controlling a shift mode, a hydraulic controller for converting line pressure fed from the shift controller into duty-controlled drive pressure or duty-controlled reverse pressure to improve shift quality and responsiveness, and a pressure distributer for selectively distributing line pressure from the shift controller and duty-controlled drive or reverse pressure from the pressure controller to each frictional element for each speed ratio while being controlled by line pressure from the shift controller.

Abstract: A manual shift control device of a transmission control system for an automotive automatic transmission. A solenoid feed valve feeds line pressure passing through a pressure regulator valve to first, second and third solenoid valves. A torque control regulator valve changes drive pressure into torque pressure. A control switch valve alternatively feeds torque pressure to first and second torque pressure passages. An N-D control valve sequentially feeds torque pressure and drive pressure to a second friction member, which is applied at an initial shift operation together with a first friction member, to thereby alleviate shift shock from neutral range "N" to drive range "D". A first-to-second speed shift valve feeds part of the torque pressure and part of the drive pressure to a third friction member during a shift operation from the first speed to the second speed.

Abstract: A shift control apparatus for an automatic transmission includes a first transmission gear unit equipped with a clutch to clutch shift mechanism and a second transmission gear unit which is operatively connected in series with the first transmission gear unit and which is equipped with a clutch to one-way clutch shift mechanism. A clutch controller controls the clutch-to-clutch shift mechanism and the clutch to one-way clutch shift mechanism in such a manner that rotational synchronization of the clutch to one-way clutch shift mechanism is caused to take place earlier than or at the same time as rotational synchronization of the clutch to clutch shift mechanism when gear shifting is effected over the first and second transmission gear units.

Abstract: An automatic transmission for an automotive vehicle comprises electromagnetic valves 5A-5C activated or deactivated in accordance with a given shift schedule determined based on traveling conditions of the automotive vehicle, a plurality of planetary gear trains 4A-4C driven by an output force of an engine, a plurality of friction devices B1-B4 and C1-C3 receiving hydraulic pressure to selectively connect or fix components constituting planetary gear trains 4A-4C, and a mechanical shift valve 6A having a pair of pressure chambers 62A and 63A and plural ports 64A, 65A and 66A. Upon application of hydraulic pressure to pressure chamber 62A, a fluid communicating path is established in the shift valve 6A so as to connect brake B1 and manual shift valve 8. When hydraulic pressure is applied to both of pressure chambers 62A and 63A, pressurized oil is drained from brake B1.

Abstract: A gear shift control apparatus for use with an automatic transmission including a friction element operable on a hydraulic pressure applied thereto in an engaged and disengaged state. A gear ratio obtained in the automatic transmission is calculated based on transmission input and output shaft speeds. A reference gear ratio is set based on at least one of the transmission input and output shaft speeds. The hydraulic pressure is changed from a first level to a second level to change the friction element from the disengaged state to the engaged state so as to produce a change from a higher gear to a lower gear when the gear ratio reaches the reference gear ratio. The reference gear ratio increases as at least one of the transmission input and output shaft speeds increases. Alternatively, the reference gear ratio may be set at a smaller value as the rate of change of the gear ratio increases.

Abstract: Power transmissions incorporate gear ratios including a plurality of forward ratios, a neutral condition and at least one reverse ratio. The establishment of each ratio is controlled by selectively engageable hydraulically operated friction devices, such as clutches and brakes. The interchange between forward ratios is controlled by the interchange of at least one friction device. The control elements to accomplish the establishment and interchange of the ratios include a pressure source, shift valve, solenoid control valves and pressure control valves. The solenoid valves are electrically actuated and the hydraulic portion of the control includes elements that permit continued operation of the transmission in selected ratios in the event of electrical discontinuance.

Abstract: Power transmissions incorporate gear ratios including a plurality of forward ratios, a neutral condition and at least one reverse ratio. The establishment of each ratio is controlled by selectively engageable hydraulically operated friction devices, such as clutches and brakes. The interchange between forward ratios is controlled by the interchange of at least one friction device. The control elements to accomplish the establishment and interchange of the ratios include a pressure source, shift valve, solenoid control valves and pressure control valves. The solenoid valves are electrically actuated and the hydraulic portion of the control includes elements that permit continued operation of the transmission in selected ratios in the event of electrical discontinuance.

Abstract: The present invention is directed toward determining when a clutch of an automatic transmission substantially fills with fluid. Once it is accurately determined when a clutch fills with fluid, then control over the transmission shifting may reliably be performed. The present invention determines when an on-coming speed clutch substantially fills with fluid in response to determining when an off-going speed clutch releases. Further, the present invention determines when an on-coming direction clutch substantially fills with fluid in response to determining when the torque converter output torque suddenly changes.

Abstract: The present invention relates to an adaptive control method for an automatic transmission. The method includes the steps of:(a) commanding a predetermined clutch to fill in accordance with a plurality of clutch fill parameters;(b) determining the actual time to completely fill the clutch;(c) comparing the actual fill time with a predetermined fill time; and(d) adjusting at least one of the plurality of clutch fill parameters in response to the comparison in order to modify the clutch fill period during subsequent shifts to the predetermined clutch. Accordingly, the present invention adapts future shifts based on past shifts to improve the shift quality of the transmission.

Abstract: The present invention provides a 4-speed transmission control system for a vehicle including a multiple stage gear mechanism receiving a driving force from an engine, a plurality of friction members for controlling a gear action of the gear mechanism, a hydraulic pressure control system for selectively applying and releasing the friction members in accordance with a vehicle speed, and a transmission control unit for controlling an operation of the hydraulic pressure control system, in which the hydraulic pressure control system has a first-to-second speed shift valve actuated in accordance with a second speed signal pressure and selectively applying more than one of the friction members, and a second-to-third speed shift valve actuated in accordance with a third speed signal pressure.

Abstract: A vehicular automatic transmission and control system therefor includes an automatic transmission including a planetary gear unit and a plurality of friction elements for connecting the components of the planetary gear unit selectively to rotary members or stationary members; a hydraulic control unit for selectively switching and controlling oil pressures to be fed to the friction elements; and an electronic control unit for outputting a signal indicating the running state of a vehicle to control the feed of the oil pressures to the friction elements.

Abstract: A rotary switch, used to select the operating range of an automatic transmission, controls solenoid-operated valves corresponding to the selected range to open and close a connection between a range valve and a control pressure source. The valve has three positions and is centered by one compression spring. One position opens the fluid pressure source to a line that is pressurized to produce forward drive, a second position opens a connection between the fluid pressure source and a line that is pressurized to produce reverse drive, and a third position vents those lines to sump. The spring locates the valve at the center position and makes the valve insensitive to tolerances and spring variations. For example, the range valve will not move until a predetermined control force is applied at either end of the valve spool.

Abstract: A rotary switch, used to select the operating range of an automatic transmission, controls solenoid-operated valves corresponding to the selected range. The valves open and close a connection between a range valve and control pressure source. The range valve includes two spools having three positions. The spools are biased apart by a compression spring located between the spools. One valve position opens the fluid pressure source to a line that is pressurized to produce forward drive, a second position opens a connection between the fluid pressure source and a line that is pressurized to produce reverse drive, and a third position vents those lines to sump. The spring locates the spools at the third position. Control pressure force on opposite ends of each spool forces both spools to the first and second positions in response to the range selected by the vehicle operator.