Abstract: Provided is a hydraulic oil control device having a shifting control unit configured to, in a case where, when upshifting is performed, a number of revolutions of an input shaft connected to a to-be-engaged clutch is higher than a number of revolutions of the engine, or a case where, when downshifting is performed, the number of revolutions of the input shaft is lower than the number of revolutions of the engine, supply the to-be-engaged clutch with a hydraulic oil having a pressure equal to or higher than a predetermined standby pressure, and then to supply the to-be-engaged clutch with the hydraulic oil having the standby pressure, and then configured to cause the to-be-engaged clutch to be engaged by supplying the to-be-engaged clutch with the hydraulic oil having a pressure higher than the standby pressure.

Abstract: An engine controller, system and method for collecting vehicle data. Drive torque data is determined using the engine controller in the vehicle and is stored in a memory in the vehicle. The drive torque data is stored in a non-time domain format, and may include a histogram of numbers of revolutions at predetermined intervals of drive torque values and/or a matrix of rainflow cycle counts. The drive torque data is temporarily stored in a buffer prior to being stored in the matrix of rainflow cycle counts using back-checking and binning. The drive torque data is downloaded from the vehicle and transmitted to a central data collection center.

Abstract: An apparatus controls a motor equipped in a hybrid vehicle. In this apparatus, a basic torque command value of the motor is calculated so as to reduce a deviation between a target rotation speed and an actual rotation speed of the motor. A torque correction value for the motor is calculated based on a variation of the target rotation speed which is obtained per unit time and a value of inertia of a power train rotated integrally with the rotation shaft of the motor. Further, a torque command value finally supplied to the motor is calculated by correcting the basic torque command value with use of the torque correction value.

Abstract: A method comprises a pre-charge step of pre-charging operating oil; a holding step of holding an operating pressure at an oil pressure less than an oil pressure during the pre-charge, for a given period of time; and a raising step of raising the operating pressure to cause an engagement-side friction element to be engaged. The method further comprises a setting step of setting a pre-charge period in the pre-charge step. The setting step includes predicting a timing at which the engagement-side friction element is to be engaged; actually measuring a timing at which the engagement-side friction element has been actually engaged; and setting the period of the pre-charge step to allow a difference between the timings to become smaller.

Abstract: A speed changing control apparatus for use in a vehicle includes: a driving power source configured to generate driving power for running; a transmission having a synchromesh mechanism configured to synchronize an input shaft revolution number with an output shaft revolution number and an actuator configured to automatically carry out a shift operation; and an automatic clutch disposed between the driving power source and the transmission. The speed changing control apparatus is configured to start a shift disengaging operation for the transmission after a speed change is requested and before the automatic clutch turns into a decoupled state, so as to suppress torsional vibration at the time of decoupling the automatic clutch. Such control enables the synchromesh mechanism to carry out revolution synchronization with the input shaft revolution number of the transmission in a lowered state, and diminishes a revolution difference subjected to synchronization.

Abstract: An exemplary control device includes an input torque detection unit that detects an input torque input to the input shaft; and a controller that: determines torque distribution of two of the friction engagement elements that form the shift speeds; and calculates a transmission torque of the two friction engagement elements based on the input torque and the torque distribution and sets the engagement pressure to obtain a torque capacity that can transmit the transmission torque, wherein the controller sets the engagement pressure such that slippage does not occur in the two friction engagement elements in a state where engagement of the two friction engagement elements forms the shift speeds and such that, even if an additional friction engagement element engages based on the line pressure while the two friction engagement elements are engaged, one of the three friction engagement elements is caused to slip.

Abstract: A control device for a vehicular automatic transmission is provided which can preferably execute backpressure control of accumulators and torque-up control so as to minimize the occurrence of interference between learning on these controls during a gearshift operation. With the control device for the vehicular automatic transmission including the accumulators (104, 106 and 108) operative to control a hydraulic pressure supplied to second and third clutches (C2 and C3) and a third brake (B3), the backpressure control is executed for controlling a backpressure of the accumulators (104, 106 and 108) during the gearshift operation while the torque-up control is executed for raising torque output from an engine (12). Completion of learning on the backpressure control is determined when no completion of learning on the backpressure control is determined, learning on the backpressure control is executed with no execution of the torque-up control.

Abstract: Features for varying speeds available and/or range of operation of transmissions are provided for use in high performance, increased efficiency, and/or other applications. Increased performance and/or efficiency may be obtained by using additional speeds or gear ranges to maintain drivetrain operation within maximum power and/or efficiency bands of internal combustion engine operation.

Abstract: A control system for a transmission coupled to an engine includes first, second, and third modules. The first module detects a closed throttle downshift of the transmission. The second module detects a request for a power-on downshift of the transmission. The third module controls a clutch of the transmission when the request for the power-on downshift is detected during the closed throttle downshift, wherein the third module one of (i) decreases a pressure applied to the clutch to a first predetermined pressure before an end of the closed throttle downshift and (ii) controls a pressure applied to the clutch to a second predetermined pressure at the end of the closed throttle downshift.

Abstract: A driving force controlling apparatus includes a driving force controller configured to determine a state of a road surface. A driving force controller is configured to control a driving force of a vehicle based on the road surface state. A rear-wheel speed sensor is configured to detect a rear-wheel speed. A low-friction-coefficient road surface determining device is configured to determine whether the road surface is a low-friction-coefficient road surface using the rear-wheel speed on a predetermined condition. A determination prohibition device is configured to prohibit the low-friction-coefficient road surface determining device from determining whether the road surface is a low-friction-coefficient road surface, if (a) the rear-wheel speed sensor is abnormal, or if (b) a predetermined time has elapsed from when a shift range is changed from a reverse range to a drive range and/or (c) a gear position has become greater than or equal to a predetermined gear position.

Abstract: An ECU executes a program having a step (S100) of detecting engine speed NE, a step (S110) of detecting turbine speed NT, a step (S120) of calculating a slip amount N(SLP) of a torque converter as (NE-NM, a step (S130) of calculating a hydraulic pressure control value based on the slip amount N(SLP) and a map, and a step (S140) of outputting a hydraulic pressure control signal to a linear solenoid. The map is set such that the hydraulic pressure control value decreases as the slip amount N(SLP) increases in positive values.

Abstract: A control apparatus for an automatic transmission includes a target-value setting section configured to set a target rotational-speed difference between input and output rotational speeds of at least one of first and second friction-engagement elements to cause the input rotational speed to be higher than the output rotational speed, when a downshift is carried out during a power-on running; a total torque-capacity calculating section configured to calculate a total torque capacity of the first and second friction-engagement elements by adding a transmission input torque to a correction value calculated from a deviation between the target rotational-speed difference and an actual rotational-speed difference, so as to bring the actual rotational-speed difference to the target rotational-speed difference; a distribution-ratio setting section configured to set a distribution ratio; an individual torque-capacity calculating section configured to calculate individual torque capacities of both second friction-engag

Abstract: A control apparatus of an automatic transmission having first and second frictional engagement elements that achieve lower and higher speed gear stages respectively, includes a target value determination section setting a rotation speed difference between input and output sides of the frictional engagement element, a total torque capacity calculation section calculating a total torque capacity, a distribution ratio determination section setting a distribution ratio of the total torque capacity to the first and second frictional engagement elements, an individual torque capacity calculation section calculating individual torque capacities respectively required of the first and second frictional engagement elements, and an engagement control section controlling engagement conditions of the first and second frictional engagement elements in accordance with the individual torque capacity.

Abstract: The present invention provides a method and apparatus for a self cleaning logic valve assembly. The logic valve assembly is adapted to cycle and thereby clean itself in response to one or more predefined parameters which are programmed into a programmable controller. The logic valve assembly is additionally configured to cycle according to one or more of several different methods which have been shown to efficiently clean the valve assembly. The cleaning process takes place during a predetermined time period selected to avoid causing an unwanted gear speed ratio change of the vehicle transmission. In this manner, the logic valve assembly may be automatically cleaned while the vehicle is being driven and without interfering with vehicle operation such that the valve cleaning is imperceptible to the operator.

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: 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: In a vehicle in which a moderate throttle opening degree control of maintaining a degree of throttle opening that is less than a degree of throttle opening that corresponds to an accelerator operation is performed for a predetermined period following a beginning of the accelerator operation, if it is determined that a clutch-to-clutch downshift judgment has been made, the reduction of the engaging pressure of a disengage-side friction engagement device is restrained until it is determined that the moderate throttle opening degree control has ended. Therefore, even if the turbine torque is returned to a normal value at the end of the moderate throttle opening degree control, insufficient engaging torque is avoided, and the takeover of engaging torque for the clutch-to-clutch downshift is smoothly performed while the turbine torque is stable. Hence, occurrence of a shock related to the end of the moderate throttle opening degree control is suitably prevented.

Abstract: A method for controlling a gear shift in an automatic transmission of a motor vehicle that is carried out as a deceleration shift of at least one engaging shifting element, without use of a mechanical free-wheeling condition. To increase the ride comfort, it is proposed that during the shifting sequence of the deceleration shift, a free-wheeling condition is simulated by a slip operation or by an opening of a second shift element of the automatic transmission, that is located in the power flow path, preferably using a start-up shift element of the automatic transmission.

Abstract: In a vehicle with a gear-shift transmission of a kind that requires a torque-free state to shift gears, the riding comfort is improved by a method of shifting gears where a gear shift is preceded by the steps of: reducing the vehicle acceleration at a time t1 from an existing level (1) to a first acceleration level (3), maintaining the vehicle acceleration at the reduced level (3) for a predetermined time interval, and at the end point t3 of the predetermined time interval, reducing the acceleration further to a second acceleration level that is lower than the first level.

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 system for an automatic transmission, which has a frictional engagement unit adapted to be kept in a slipping state when in a predetermined speed changing state and in an applied state when in another gear ratio changing state; and a drain oil establishing member for establishing a drain oil when the frictional engagement unit is kept in the slipping state comprises a drain pressure switching mechanism for supplying the drain oil to the frictional face of the frictional engagement unit when the frictional engagement unit is kept in the slipping state.

Abstract: A hydraulic control system includes switching mechanisms for receiving as a signal voltage 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: A forced downshift control method for automatic transmissions, wherein, if shift signals of a forced 4-2 downshift are input, a first shift control solenoid valve (SCSV-A) is controlled to OFF; a second shift control solenoid valve SCSV-B is maintained in an OFF state for a predetermined period of time (t1) then controlled to ON; a third shift control solenoid valve (SCSV-C) is continuously maintained in an ON state, then is immediately controlled to OFF and first and second pressure control solenoid valves (PCSV-A) and (PCSV-B) are duty controlled.

Abstract: A power-on manual downshift control method including the steps of determining if a power-on manual downshifting is being performed or not when a TCU receives a power-on manual downshifting signal, producing a duty control signal of 0% if power-on manual downshifting is being performed, determining if a shift begin point is detected or not, compensating for a feedback start duty ratio and producing a compensated duty ratio Dr if the shift begin point is detected, maintaining the state for a predetermined period of time Ta, executing a feedback control sub-routine on ending of the predetermined period of time Ta, reducing the duty ratio Dr by as much as a predetermined duty amount &Dgr;d on ending the feedback subroutine and maintaining this state for 8 ms, and ending the duty control if the duty ratio Dr reaches 0%.

Abstract: A control system for an automatic transmission, which is capable of controlling the hydraulic pressures for frictional engagement units when a predetermined shift is performed such that a first frictional engagement unit is engaged and a second frictional engagement unit is released, being connected to a power source, the revolving speed of which is temporarily raised when a predetermined shift down is performed, the control unit for the automatic transmission for a vehicle being structured such that shift which is performed by engaging and releasing the two frictional engagement units is judged, whether the judged shift is shift down in which the revolving speed of the power source is temporarily raised or shift down in which the revolving speed of the power source is not raised is judged, and the contents of control of the hydraulic pressures for the frictional engagement units are changed between shift down in which the revolving speed of the power source is temporarily raised and shift down in which the r

Abstract: A powershift transmission of an engine-driven vehicle includes input and output shafts, a plurality of fluid pressure operated clutch for controlling flow of torque through the transmission and pressure control valves for controlling fluid pressure communicated to the clutches. A method of controlling an off-going clutch during a shift of the transmission includes detecting a load on the engine, as a function of the detected load, determining a slip pressure, which when applied to the clutch would cause the clutch to slip, and applying the slip pressure to the clutch. If the clutch is not slipping, the pressure applied to the clutch is reduced until relative rotation (slip) between the input and output elements of said clutch is detected. Then a pressure increase is determined, which when applied to the slipping clutch would allow the slipping clutch to continue to slip while transmitting the same torque it was transmitting before it began to slip.

Abstract: The present invention provides a method for shifting from a first gear state to a second gear state which holds one element at a predetermined level until the second reaches its fill volume. In this method, one element is applied while the other element is released. The element which reaches its fill volume first is held at a control limit. This control limit is defined by a volume between the first clutch element and a predetermined point above the fill volume of the first clutch element. This clutch element is then maintained at within the control limit until the other clutch element reaches its fill volume. The maintained clutch element is then released shortly after the other clutch element has reached its fill volume. This method ensures that neither fighting or slipping occurs between the two elements.

Abstract: A control system for an automatic transmission, which is capable of controlling the hydraulic pressures for frictional engagement units when a predetermined shift is performed such that a first frictional engagement unit is engaged and a second frictional engagement unit is released, being connected to a power source, the revolving speed of which is temporarily raised when a predetermined shift down is performed, the control unit for the automatic transmission for a vehicle being structured such that shift which is performed by engaging and releasing the two frictional engagement units is judged, whether the judged shift is shift down in which the revolving speed of the power source is temporarily raised or shift down in which the revolving speed of the power source is not raised is judged, and the contents of control of the hydraulic pressures for the frictional engagement units are changed between shift down in which the revolving speed of the power source is temporarily raised and shift down in which the r

Abstract: A vehicle automatic transmission control controls fluid pressure changes applied to a frictional engagement element which is being changed from an engaged state to a disengaged state at a stage before input shaft rotational speed starts to increase from the beginning of a down-shift control. The control instruction value is set to gradually decrease the applied fluid pressure and to increase the ratio of such decrease with elapsed time. Specifically, a solenoid is used to control the fluid pressure applied to a clutch. The duty-cycle instruction for the solenoid is determined based on a quadratic function expressed as: duty cycle value=initial value-at.sup.2.

Abstract: In a gearshift control apparatus for an automatic transmission which performs a downshift under power ON state, after a command for a clutch-to-clutch downshift has been issued, the hydraulic pressure of a higher-speed-stage side clutch is first lowered to raise the input r.p.m. of the transmission. When the beginning of rise in the input r.p.m. of the transmission has been detected, the hydraulic pressure of the higher-speed-stage side clutch is subjected to a feedback control so that the change rate of the input r.p.m. of the transmission may become a specific value. Upon the detection that the input r.p.m. of the transmission have come near to the synchronous r.p.m. of a lower speed stage, the hydraulic pressure of the lower-speed-stage side clutch is gradually raised, and simultaneously, the hydraulic pressure of the higher-speed-stage side clutch is subjected to a feedback control on the basis of the input r.p.m. of the transmission.

Abstract: A hydraulic control system for automatic transmissions includes a pressure control valve for regulating hydraulic pressure generated by a hydraulic pump to line pressure, a manual valve for converting the line pressure from the pressure control valve into drive pressure, a solenoid supply valve for reducing the line pressure from the pressure control valve, a torque control regulator valve controlled by the reduced pressure from the solenoid supply valve to convert the drive pressure from the manual valve into torque pressure that is lower than the drive pressure, and a shift valve for supplying the torque pressure from the torque control regulator valve to friction elements during an initial stage of a shift operation, then replacing the torque pressure with the drive pressure from the manual valve at an end of the shift operation.

Abstract: A system for controlling an automatic vehicle transmission, including a gear system and hydraulic clutches which hold a member of the gear system stationary to produce gear reduction or reverse, having an oil line which connects the clutches to an oil pressure source, a pressure control valve having a solenoid provided in the oil line which generates a regulated oil pressure to be supplied to the clutches in response to a current supplied to the solenoid, a switch valve provided in the oil line which switches the oil pressure to be supplied to the one of the clutches between the regulated oil pressure and a line pressure. In the system, it is discriminated whether the pressure control valve does not supply the regulated oil pressure to the clutches and if so, a dither current is supplied to the solenoid such that the valve repeatedly performs a vibrational motion to remove any grit therefrom, thereby removing grit without causing gear-shift shock or clutch vibration.

Abstract: A hydraulic control system for an automatic transmission includes a pressure regulator to regulate hydraulic pressure produced by an oil pump; a manual and automatic shift controller to form shift modes; and a hydraulic pressure controller to regulate shift quality and responsiveness such that shift modes are smoothly formed during shifting. A damper clutch controller operates a damper clutch of a torque converter. A hydraulic pressure distributor supplies and distributes appropriate amounts of hydraulic pressure to friction members that operate as input and reaction members in each shift stage.

Abstract: A method of controlling and regulating an automatic transmission with overlapping gearshifts. The change from the control mode to the regulating mode for the disengaging clutch (11) is made here when a defective engagement of the engaging clutch (12) is detected.

Abstract: A control system for downshifting an automatic transmission provides reduced shift shock by controlling pressure fed to a kickdown servo brake. A throttle valve sensor, an input shaft rpm sensor, an output shaft rpm sensor, and a transmission control unit are used. The transmission control unit outputs a control signal for a second-to-first speed shift after reducing hydraulic pressure fed in accordance with a duty pattern when the vehicle is in the state of a second-to-first downshift. Alternatively, the transmission control units outputs a control signal for a second-to-first speed shift after the third-to-second speed shift is completed when the vehicle is in the state of a third-to-first speed shift. In any case, the transmission control units controls first and second transmission control solenoid valves, and a hydraulic pressure control solenoid valve for changing the state of hydraulic pressure fed to every friction member.

Abstract: In a shift control apparatus in a vehicle automatic transmission, up-shift is carried out from a low velocity step to a high velocity step. When a rotational blow is generated, a controlling device controls the releasing side element of frictional engaging elements in such a target that the releasing side element of frictional engaging elements slips on the mating member with the engaging side element of frictional engaging elements moving for engagement.

Abstract: A speed change control system for an automatic transmission for making a speed change of the automatic transmission by applying/releasing frictional engagement elements and for controlling a line pressure, to be fed to the frictional engagement elements, to a pressure according to a throttle opening. The speed change control system detects a downshift of the automatic transmission with the throttle opening being increased, to control the line pressure to a level lower than that according to the throttle opening, if the downshift is detected. As a result, the torque transmission capacities of the frictional engagement elements, even if they are of the hydraulic type in which they are applied at the downshift, can be preventing from increasing during the speed change, thereby to improve the shift shock at the downshift.

Abstract: An automatic transmission control system for an automatic transmission including a hydraulic pressure control circuit which supplies locking and unlocking pressures selectively to a plurality of friction coupling elements to lock and unlock the selected friction coupling elements, changing a torque transmission path in a transmission gear mechanism to provide available gears, a specific one of which is achieved by locking and unlocking simultaneously specific friction coupling elements.

Abstract: A hydraulic control device determines whether the transmission is being shifted down, and upon determination of the shift-down action, determines whether the vehicle is in a power-on condition or in a power-off condition. Upon determination of the power-off condition, the hydraulic control device regulates the control oil pressure applied to the engaging element, such that the oil pressure is rapidly increased from the beginning of a shifting process, and is maintained at a high level until the shifting process is about to be completed. Upon determination of the power-on condition, the control device regulates the control oil pressure such that the oil pressure is maintained at a low level from the beginning of the shifting process, and is increased just before completion of the shifting process.

Abstract: A process is proposed for controlling an automatic transmission where changing from one gear speed to another is brought about as a result of a first clutch (11) opening and a second clutch (12) closing. It is further proposed to apply the process to a group transmission.

Abstract: An interactive cruise control system and method for providing automatic speed control of a vehicle with improved shifting of an automatic transmission. The system and method controls speed of a vehicle equipped with cruise control and minimizes downshifts in an automatic transmission of the vehicle. Vehicle speed is detected and compared with a setpoint speed which is associated with the cruise control system. Transmission gear shifting is determined based on predetermined shift schedule points. Determined transmission gear downshifts are prevented for a kickdown delay period based on vehicle speed loss and the presence of vehicle deceleration. Also provided is an overspeed reduction method for causing a transmission downshift during an overspeed condition with the throttle closed. Further, the system provides hunting prevention between both second gear and third gear as well as between third gear and fourth gear for a four speed automatic transmission.

Abstract: A kickdown control method for automatic transmission wherein a transmission control unit TCU receives signals regarding three variables for a throttle opening rate just prior to an abrupt operation of the accelerator pedal, the vehicle speed and the throttle opening rate changes during the operation of the accelerator pedal; if the throttle opening rate is lower than 20%, the vehicle speed is lower than 20 Km/h and the throttle opening rate change is lower than 30%, the transmission control unit TCU applies to the pressure control solenoid valve a first duty control pattern in which duty rate is constant with respect to time changes from shift start point; and if any one of said variables equal to or higher than the above reference values, the transmission control unit TCU applies to the pressure control solenoid valve a second duty control pattern in which the applied duty rate changes in multi-steps with regard to time change from shift start point.(Fig.

Abstract: A process is proposed for controlling an automatic transmission wherein a transition occurs from a first, lower reduction step to a second, higher reduction step when a first clutch disengages and a second clutch engages and a synchronizer speed is calculated by multiplying the transmission output speed by the reduction ratio of the second reduction step. A speed value, at which the pressure increase of the second clutch begins, is assigned to the synchronizer speed from a characteristic curve. The characteristic curve is adapted if the transmission input speed exceeds the synchronizer speed or if the gradient of the transmission input speed exceeds a limit value.

Abstract: An automatic transmission control device for use in controlling an automatic transmission that includes a plurality of friction engaging devices disposed between the rotational shaft of the engine and the output shaft in order to control gear ratios includes a control device which controls the engaging operation and the disengaging operation of each of the friction engaging devices. The control device changes the time when the engagement side friction engaging device begins to engage based on the gear ratio from which the power-on down shift operation is being made and the gear ratio to which the power-on down shift operation is being made. Thus, in the case of a 4.fwdarw.2 power-on down shift operation the time when the engagement side friction engaging device begins to engage is longer than during a 3.fwdarw.2 power-on down shift operation. In this way, temporary increases in the engine rotational speed are prevented and shift shock is avoided.

Abstract: The invention relates to a process for the adaptive correction of the shifting quality of an automatic transmission which is coupled to an engine and in which correcting elements acting on the pressure or oil throughput bring friction elements into engagement in the form of clutches or brake bands to carry out shifting processes, the line pressure impinged on by the correcting elements being registered by means of an electronic device and corrected as a function of various operating parameters.

Abstract: An automobile automatic transmission shift control system causes a specific gear shift by locking a first frictional element and unlocking a second frictional element simultaneously. The system delays a commencement of the unlocking of the second frictional element relative to a commencement of the locking of the first frictional element during the specific gear shift while a down control of engine torque is not conducted or when an engine output torque is large.

Abstract: An electronic transmission coastdown shift control method in which the transmission controller has the capacity to predict timing of apply element application. The control method of the present invention improves the shift sequence by accurately prefilling the apply element. The transmission controller vents the release element when apply element application is imminent and controls the application of the oncoming element to achieve a controlled element exchange for a smooth coastdown shift. A duty cycle is then applied to complete the oncoming element application with a soft yet quick application and control the engagement of the oncoming element. The identification of the application point of the oncoming element enables the apply element fill volume to be learned during coastdown shifts. It also enables the calculation of a line pressure correction factor necessary in accurately predicting application of the apply element. Anticipation of a coastdown tip-in condition is also provided.

Abstract: In an arrangement for automatically changing gear in an epicyclic change-speed gearbox from a previous gear, in which a first frictional connection (clutch or brake) is engaged, into another gear, in which a second frictional connection is engaged, the working pressure for engaging the first frictional connection is switched off when the working pressure for engaging the second frictional connection reaches a significant pressure value. The pressure value is determined by comparison with a reference parameter which depends on the load torque.

Abstract: In a control system for an automatic transmission, when successive order signals are emitted so that shift changes are accomplished over multiple shift stages, a shift change ordered by an initial order signal is carried out before a shift change ordered by a last order signal is carried out if a shift gear mechanism has already started its operation. However, a shift change ordered by a last order signal is carried out, without shift changes ordered by an initial order signal and intermediate order signals being carried out, if the shift gear mechanism has not started its operation.

Abstract: An oil pressure control system for an automatic transmission for executing a downshift by disengaging a first frictional engagement element and engaging a second frictional engagement element. At a latter stage of a shift, the first frictional engagement element has its torque capacity increased by raising its oil pressure temporarily. After this, if a synchronization substantially reaching the revolution number at a gear stage after the downshift is detected, the first frictional engagement element has its torque capacity gradually dropped by dropping the oil pressure thereof gradually, and the second frictional engagement element has its oil pressure abruptly raised.