Abstract: The shift control system and method for an automatic transmission of a vehicle, wherein the automatic transmission includes a hydraulic control system controlling a plurality of friction elements, senses vehicle operating conditions. Based on the sensed vehicle operating conditions, a control unit decides whether to perform a downshift from a higher speed stage to a lower speed stage. The control unit also feedback controls the hydraulic pressure in the hydraulic control system during the downshift when the control unit decides to perform such a downshift. The feedback control serves to lengthen the downshift operation such that shift shock is reduced.

Abstract: In a driven state, a hydraulic pressure of disengagement side is set at a stroke pressure, a one-way clutch in an operating state is over-run, an engine rotation speed is in an idle state, and an automatic transmission is in a neutral state. In a drive state, the hydraulic pressure of disengagement side is controlled so that a difference between an engine rotation speed and an input rotation speed reaches a difference between the both rotation speeds at a start of the shift control. In a state of a synchronized rotation after the shift, the hydraulic pressure of disengagement side is controlled so that the input rotation reaches the synchronized rotation.

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: Disclosed is a hydraulic control system for automatic transmissions including a plurality of friction elements, comprising a hydraulic pressure source; hydraulic pressure regulating parts for controlling hydraulic pressure from the hydraulic pressure source; damper clutch control parts for actuating a damper clutch of the torque converter by supplying hydraulic pressure fed from the pressure regulating parts to the torque converter; shift control parts for selecting a shift mode by converting hydraulic pressure from the pressure regulating parts into drive pressure; hydraulic pressure control parts for controlling the drive pressure from the shift control parts; and hydraulic pressure distributing parts for suitably distributing hydraulic pressure from the hydraulic pressure control parts to each friction element, said hydraulic pressure distributing parts comprising a 1-2 shift valve; a 2-3/4-3 shift valve; and shift timing control parts having a shift timing control valve for supplying hydraulic pressure to

Abstract: A self-organizing fuzzy logic controller develops an adaptive pressure adder that modifies the magnitude of pressure supplied to a friction element of an automatic transmission. The controller uses a turbine speed versus engine torque table in KAM to store the adaptive pressure adder for each shift. Tables in KAM represent fuzzy rules which are altered based on shift performance criteria to produce a self-organizing fuzzy logic controller. The criteria, which define shift performance, include the ratio change slip time and the initial ratio change time divided by the desired slip time (called target ratio). The desired slip time is determined from a calibratable matrix. After a shifting event, an adaptive pressure adjustment is determined for the next shifting event having the same conditions. A two-input (slip time and target ratio) fuzzy logic controller is used to determine the pressure adjustment.

Abstract: In power-on, high-vehicle-speed and high-torque conditions, a control unit sets a torque allotment ratio such that a main clutch bears all the torque. Thereby, the input shaft rotational speed is increased by controlling solely the main clutch releasing pressure. In power-on and low-torque or low-vehicle-speed conditions, the control unit sets a torque allotment ratio for the main clutch torque and the sub-clutch torque to 1:1. Thereby, control of the main clutch releasing pressure and control of the sub-clutch engaging pressure simultaneously proceed in parallel to produce a change in the input shaft rotational speed without a time lag. The hydraulic control apparatus thus conducts proper downshift control for a shift involving clutch engagement changeover, under all vehicle running conditions, without need for additional control logic.

Abstract: A changeover valve (13) connected to a shift valve unit (12) via four oil passages L3-L6, and two pressure regulating valves (14.sub.1, 14.sub.2) are provided. At speed changing when the changeover valve (13) is in a first (right) position, an off-going hydraulic clutch is connected to oil passage L3 to control its pressure drop by the pressure regulating valve (14.sub.1) and an on-coming hydraulic clutch is connected to L5 to control its pressure rise by the pressure regulating valve (14.sub.2). After completion of the speed changing, the changeover valve (13) is switched to a second (left) position. At speed changing when the changeover valve (13) is in the second position, an on-coming hydraulic clutch is connected to L4 to control its pressure rise by the pressure regulating valve (14.sub.1) and an off-going hydraulic clutch is connected to the L6 to control its pressure drop by the pressure regulating valve (14).

Abstract: A downshift control device for an automatic transmission is provided in which the transmission is shifted down by releasing an oil pressure from a first engaging element that has been engaged while applying an oil pressure to a second engaging element that has been released.

Abstract: A hydraulic control system for shifting an automatic transmission to desired gears by selectively coupling and uncoupling friction coupling elements which controls a shifting pressure necessary to bring a friction coupling element into coupling according to a presumed friction coefficient of the friction coupling element during shifting so as thereby to achieve an intended gear shift over an intended shifting time.

Abstract: An apparatus for controlling the pressure of a hydraulically operated frictional coupling device which is released or engaged to achieve a shifting action of an automatic transmission, by first rapidly reducing or increasing the pressure to a predetermined level, holding the pressure at this level for a predetermined time and then continuously reducing or increasing the pressure to complete the shifting action. A learning compensation device is provided to update, by learning compensation, a selected control parameter influencing a pattern of change of the pressure of the coupling device during the shifting action such that the shifting action is achieved in a predetermined manner.

Abstract: The method of controlling a pressure control solenoid valve which controls hydraulic pressure in a hydraulic control system for an automatic transmission of a vehicle first senses a plurality of vehicle operating conditions, and detects a power-on vehicle operating state based on the sensed vehicle operating conditions. Next, the method controls a duty ratio of the pressure control solenoid valve according to predetermined values corresponding to the power-on state when the power-on state detected. The method then detects a change in the vehicle operating state from the power-on state to a power-off state. Upon detection, the method generates an initial duty ratio for the pressure control solenoid valve based on a predetermined duty ratio corresponding to the power-off state and duty ratios supplied to the pressure control solenoid valve during the power-on state. The pressure control solenoid valve is then controlled according to this initial duty ratio during the power-off state.

Abstract: A shift control apparatus in a vehicle automatic transmission, where down-shift is carried out from a high velocity step to a low- velocity step.A flatness-aiming control has a common targetted change rate with respect to a turbine rotational speed in the inertia phase, and aims a hydraulic command value for the engaging side element and a hydraulic command value for the releasing side element at flatness in the inertia phase with the passage of time.An initial value setting control sets an engaging side initial value and a releasing side initial value at the beginning of the inertia phase in response to the turbine torque and the turbine rotational speed.

Abstract: To optimize the application hydraulic pressure of the friction application elements in the transmission mechanism, and to reduce the unnecessary load on each member, the transmission mechanism of an automatic transmission is provided with a plurality of friction application elements which are applied simultaneously in order to achieve the designated gear stage, and hydraulic servos which operate the friction application elements independently. The control apparatus has an information detecting means, an input torque calculating means which calculates the input torque of the transmission mechanism on the basis of this information, an application hydraulic pressure calculating means which calculates the necessary application hydraulic pressure required to maintain the application of each individual friction application element on the basis of the input torque, and a supply means which supplies the necessary application hydraulic pressure to the hydraulic servos of the friction application elements.

Abstract: A control system of an automatic transmission includes a torque converter, a lock-up clutch for directly connecting input and output members of the torque converter, a pressure control valve which changes a hydraulic pressure to control an engaging force of the lock-up clutch, and a pressure regulator, disposed in an engaging passage, which supplies hydraulic pressure to engage a frictional element. The pressure regulator adjusts a primary pressure and produces an output hydraulic pressure corresponding to a control pressure introduced into a control port of the pressure regulator. A control pressure supply device is provided for introducing the control pressure, controlled by the pressure control valve, into the control port of the pressure regulator. The number of parts can be reduced without producing any inconvenience.

Abstract: Uncomfortable travel of a vehicle due to engine brake actions during the travel of the vehicle in traffic is prevented without using an one-way clutch within a transmission mechanism. An automatic transmission is composed of rotational elements that are braked at the time of establishing low stages, a brake that brakes the rotational elements, and control systems which control the oil pressure of the hydraulic servo in the brake. A band brake that creates differences in application forces, using self-energizing and deenergizing actions, serves as the brake, which is set to have an area in which the oil pressure during the drive is lower than the oil pressure during the non-drive, by setting the self-energizing direction as a direction of rotation of the rotational element during the drive and the deenergizing direction as an opposite direction of rotation of the rotational element during the non-drive.

Abstract: A speed change control system for use in an automatic transmission includes a one-way clutch to be locked and to retain a rotary element in a speed change mechanism for establishing a predetermined gear stage and an engine braking frictional engagement element arrayed in parallel with the one-way clutch and adapted to retain the rotary element, thereby establishing the desired gear stage. The speed change control system further includes a throttle opening detector for detecting the stroke of depression of the accelerator pedal of a vehicle, a downshift detector for detecting a shift to a desired gear stage and an apply pressure controller for controlling the apply pressure of the engine braking frictional engagement element. A speed change decision is made to determine whether a speed change is ended for a predetermined time period, if the throttle opening is in a predetermined region and if the detected shift is a downshift to the desired gear stage.

Abstract: The present invention is directed to methods and systems for improving the operation of a transmission for an automotive vehicle, and in particular the transmission as installed by the original automobile manufacturer. The methods and systems of the present invention modify the original hydraulic fluid circuits of the automotive transmission provided by the automobile manufacturer to enable the transmission to manually select any available ratio at any time, to select first gear at any time, and to enable the transmission to produce quick applies during upshifts and fast releases during downshifts for improved performance and heavy duty use with only minimum ratio sharing or overlap during gear changes.

Abstract: An automatic transmission control system for controlling oil pressure of a frictional engagement device in accordance with an input torque to an automatic transmission, comprising: a plurality of input torque estimating devices for estimating the input torque to the automatic transmission; a first oil pressure determining device for determining the oil pressure on the basis of the input torque to the automatic transmission, as estimated by any of the input torque estimating device; a trouble deciding device for deciding a trouble about the input torque value estimated by any input torque estimating device; and a second oil pressure determining device for determining the oil pressure on the basis of the input torque to the automatic transmission, as estimated by another input torque estimating device, if the trouble deciding device decides a trouble about the input torque value estimated by any input torque estimating device.

Abstract: A control system for an automatic transmission includes: a clutch adapted to be applied when a forward running range is selected, to transmit the rotation of an engine to the transmission mechanism of a speed change unit and a hydraulic servo for applying/releasing the clutch. A control unit controls oil pressure fed to the hydraulic servo and includes: an application starting pressure detector for detecting application starting pressure at the instant when the application of the clutch is started; an initial application pressure setter for setting an initial application pressure on the basis of the detected application starting pressure; and an oil pressure regulator for adjusting the oil pressure fed to the hydraulic servo, when a change is made to a forward running range, and then gradually raising that oil pressure.

Abstract: A control system for an automatic transmission operates a clutch for disengaging a transmission mechanism when a vehicle is stopped and idling with the brake pedal depressed while the gear shift is in a forward gear. The clutch is maintained at a drag state (friction elements disengaged but oil causing some torque transmission) bordering a slip state (friction elements engaged) When a neutral control is started, the clutch is released until the retraction of the piston of the hydraulic servo is started. When the rate of change in a rotational difference does not exceeds a reference rate of change even after a set time has elapsed, booster means of specific release state holding means decides that the clutch is in a drag region, and raises an oil pressure to be fed to the hydraulic servo, by a set pressure.

Abstract: A system for controlling a pump in a hydraulic circuit for an automatic transmission, having a viscosity insensitive fixed orifice and a relatively high resistance laminar orifice connected in series relationship between a vent port and a control pressure supplied to a secondary regulated pressure SRP valve. At relatively low temperature, flow through the laminar orifice is negligible; therefore, the steady-state differential pressure across the fixed orifice is negligible. At relatively higher temperatures, flow through the laminar orifice increases. A pressure divider is established and the feedback differential pressure is reduced in proportion to the hydraulic resistance of the two orifices. Flow to friction elements from a primary pump and auxiliary pump and return of fluid to the inlets of the pumps is controlled through a clutch capacity pressure regulator valve acting in cooperation with the SRP valve.

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: A controller (100 in FIG. 1) for relieving a gear shift shock in a vehicle, comprising an input torque calculation portion (131) which calculates the input torque (T.sub.t) of the stepped automatic transmission mechanism of the vehicle from engine r.p.m. (N.sub.e) and turbine r.p.m. (N.sub.e), a shift start recognition portion (134) which recognizes the real mechanical shift start timing of the stepped automatic transmission mechanism in accordance with the change of the input torque (T.sub.t), a line-pressure correction magnitude calculation portion (142) which calculates a line-pressure correction magnitude (.DELTA.PL) during the gear shift operation of the stepped automatic transmission mechanism when the shift start has been recognized, a standard line pressure calculation portion (143) which calculates a standard line pressure (PL), and a command line pressure calculation portion (144) which adds the line-pressure correction magnitude (.DELTA.

Abstract: A control system for use in an automatic transmission having a transmission mechanism for establishing a plurality of forward stages, a neutral state and a reverse stage. The transmission mechanism includes a predetermined rotary element to be retained for establishing the reverse stage; a reverse brake for retaining the rotary element; and a frictional engagement element capable of stopping the rotation of the rotary element. The reverse brake is a meshing type brake which meshes with and retains the rotary element. The control system has an engagement mechanism for applying the frictional engagement element. When the reverse stage is selected, the frictional engagement element is applied at least until the meshing engagement of the reverse brake is established, to stop the predetermined rotary element.

Abstract: A hydraulic pressure control apparatus for an automatic transmission including a microprocessor-based control unit for controlling hydraulic pressure supplied to hydraulic servos of friction engagement elements. The control apparatus calculates a target hydraulic pressure P.sub.TA for a condition at the start of the inertia phase in accordance with the input torque, and a gradient based on the target hydraulic pressure and a predetermined time t.sub.TA. A first up-sweep of hydraulic pressure is performed by the apparatus with the gradient. A relatively gradual gradient .delta.P.sub.TA is set based on a target rotation change rate for the input rotational speed to provide a predetermined change amount when the hydraulic pressure becomes the target hydraulic pressure P.sub.TA. The control apparatus performs a second up-sweep with the gradient .delta.P.sub.TA. When the rotational speed change .DELTA.N of the input rotation becomes a rotation change start-determining rotational speed dN.sub.

Abstract: A controller (100 in FIG. 1) for relieving a gear shift shock in a vehicle, comprising an input torque calculation portion (131) which calculates the input torque (T.sub.t) of the stepped automatic transmission mechanism of the vehicle from engine r.p.m. (N.sub.e) and turbine r.p.m. (N.sub.e), a shift start recognition portion (134) which recognizes the real mechanical shift start timing of the stepped automatic transmission mechanism in accordance with the change of the input torque (T.sub.t), a line-pressure correction magnitude calculation portion (142) which calculates a line-pressure correction magnitude (.DELTA.PL) during the gear shift operation of the stepped automatic transmission mechanism when the shift start has been recognized, a standard line pressure calculation portion (143) which calculates a standard line pressure (PL), and a command line pressure calculation portion (144) which adds the line-pressure correction magnitude (.DELTA.

Abstract: A controller (100 in FIG. 1) for relieving a gear shift shock in a vehicle, comprising an input torque calculation portion (131) which calculates the input torque (T.sub.t) of the stepped automatic transmission mechanism of the vehicle from engine r.p.m. (N.sub.e) and turbine r.p.m. (N.sub.e), a shift start recognition portion (134) which recognizes the real mechanical shift start timing of the stepped automatic transmission mechanism in accordance with the change of the input torque (T.sub.t), a line-pressure correction magnitude calculation portion (142) which calculates a line-pressure correction magnitude (.DELTA.PL) during the gear shift operation of the stepped automatic transmission mechanism when the shift start has been recognized, a standard line pressure calculation portion (143) which calculates a standard line pressure (PL), and a command line pressure calculation portion (144) which adds the line-pressure correction magnitude (.DELTA.

Abstract: A method for shifting a powershift transmission of a vehicle in accordance with the load being experienced by the engine as estimated from certain engine operating parameters. A turbocharger associated with an engine operating at a given engine speed generates a turbo boost pressure. The turbo boost pressure is monitored by a sensor and a turbo boost signal is generated therefrom. Similarly, the engine speed is monitored by a sensor and an engine speed signal is generated therefrom. The turbo boost and engine speed signals are used to estimate the engine load based on empirical data stored in the transmission controller's memory, and a percentage load is computed therefrom. The percentage load is then used to generate an appropriate duty cycle and time value for a pulse-width-modulated shift signal which controls the modulation of an on-coming directional clutch into engagement at a desired rate of engagement dependent upon the load being experienced by the vehicle.

Abstract: A controller (100 in FIG. 1) for relieving a gear shift shock in a vehicle, comprising an input torque calculation portion (131) which calculates the input torque (T.sub.t) of the stepped automatic transmission mechanism of the vehicle from engine r.p.m. (N.sub.e) and turbine r.p.m. (N.sub.e), a shift start recognition portion (134) which recognizes the real mechanical shift start timing of the stepped automatic transmission mechanism in accordance with the change of the input torque (T.sub.t), a line-pressure correction magnitude calculation portion (142) which calculates a line-pressure correction magnitude (.DELTA.PL) during the gear shift operation of the stepped automatic transmission mechanism when the shift start has been recognized, a standard line pressure calculation portion (143) which calculates a standard line pressure (PL), and a command line pressure calculation portion (144) which adds the line-pressure correction magnitude (.DELTA.

Abstract: A power transmission control selectively establishes five forward speeds and one reverse speed by the controlling of three relay valves and two variable pressure TRIM valves. The TRIM valves normally control the pressure in the on-coming and off-going friction devices, respectively. The TRIM valves switch functions between ranges. In the fifth speed, the relay valves provide a pathway or passage for directing the fluid output of one of the TRIM valves to a control area on a system regulator valve to effect a variable main pressure.

Abstract: A method of establishing an adaptive pressure term in an automatic transmission having a pressure command developed from a base line pressure term and an adaptive pressure term extends implementation of adaptive pressure corrections during non-ideal periods of operation such as low temperatures, short operating cycles and driver variations by establishing an adaptive pressure term proportional to a measure of confidence in a pressure correction term calculated at each ratio change of the transmission. The measure of confidence is determined according to a variety of functions of predetermined powertrain operating parameters and measures of criticality.

Abstract: A working fluid pressure control system for an automatic power transmission includes a pre-charge pressure regulating mechanism for temporarily elevating a working fluid pressure abruptly and subsequently drop the working fluid pressure for generating a pre-charging constant pressure for a start-up friction element, and a detecting portion for detecting an operational range before selection of neutral range. When selection is made from neutral range to a traveling range, and the traveling range is different from the operational range before selection of the neutral range, the pre-charge pressure regulating mechanism is actuated when judgement is made that the start-up friction element engaged in the operational range before selection of neutral range is released, thus selection being performed within a short period without accompanying with a shock.

Abstract: Methods and systems for improving the operation of a transmission for an automotive vehicle, and in particular the transmission as installed by the original automobile manufacturer, modify the original hydraulic fluid circuits of the automotive transmission installed by the automobile manufacturer to enable the "factory installed" transmission to hold first gear in the first gear selector position through any rotational speed of the engine. Further modifications to the hydraulic circuitry enable the operator of the vehicle to select fourth gear manually at relatively high vehicle speeds at wide open throttle conditions. Additional modifications to the hydraulic circuitry increase the third clutch capacity at high throttle during a "2-3" shift, and result in firm and more correctly timed shifts.

Abstract: An automatic transmission control apparatus has a clutch, a hydraulic servo for the clutch, a fluid pressure control unit, a range shift detector, and an electronic control unit. The fluid pressure control unit has a manual valve, a pressure regulating valve device, and a changeover valve device. The electronic control unit controls the changeover valve device and the pressure regulating valve device. Immediately after a shift to the forward driving range, the electronic control unit holds the changeover valve device in such a state that a forward driving range pressure is supplied without passing through the pressure regulating valve device. Then, the electronic control unit shifts the changeover valve device to such a state that a regulated pressure is supplied from the pressure regulating valve device, which has been switched to a pressure regulating state by the electronic control unit. This control operation precisely sets the fluid pressure changeover timing and the initial fluid pressure.

Abstract: A sharp-edged orifice, located in an hydraulic circuit between a lubrication system and a source of lubrication, is connected to a flow control valve, which balances the differential pressure across the orifice and throttles the source of fluid pressure to a lubrication feed line. A lube augmentation valve, responsive to pressure, present when operating in forward drive, alternately opens and closes lubrication fluid flow through a second sharp-edged orifice located in a line arranged in parallel with the first orifice and connected downstream from that orifice and upstream from the lubrication circuit.

Abstract: A vehicle automatic transmission control system, in which when a gear to be shifted to is determined in response to the throttle opening and vehicle speed, hydraulic oil is supplied to a clutch for the gear to be shifted to. In an early period of the gearshift, the hydraulic oil is supplied to decrease a time lag between an output of the gearshift command and a start of clutch engagement. In the system, there is provided, instead of an expensive oil pressure sensor, a means for estimating or detecting the clutch oil pressure as a capacity of power which the clutch can transmit. When the estimated or detected pressure is high, the supply of oil to the clutch is prohibited so as to prevent sudden clutch engagement which would otherwise produce shock.

Abstract: A vehicle automatic transmission control system having a torque converter having an input connected to an internal combustion engine mounted on the vehicle and an output connected to a gear system of the transmission, which makes it possible to estimate an ATF temperature without using an expensive ATF temperature sensor. The estimation of the ATF temperature is configured such that based on the coolant temperature at engine starting, it calculates the temperature increase owing to heat inflow to the ATF per unit time and the temperature decrease owing to heat outflow from the ATF per unit time quantitatively and uses the sum of the calculated values to determine the estimated ATF temperature TATF. The parameters used for calculating the temperature include the state of the torque converter, the type of gearshift, a vehicle speed (temperature increase owing to stirring of the ATF), the state of a heat exchanger, and the like.

Abstract: A hydraulic control system for an automatic transmission comprising a shift speed mechanism, a frictional element hydraulically controlled for switching a power transmitting path in the shift speed mechanism, a working pressure controller for controlling an engaging force of the frictional element during a shift operation by adjusting a working pressure applied to the frictional element, a calculator for calculating separately an input torque pressure corresponding to an input torque introduced to the shift speed mechanism and an inertia torque pressure corresponding to an inertia torque which is changed in accordance with a speed change of the shift speed mechanism, and a learning control compensator for compensating the inertia torque pressure by means of a learning control. The shift shock is effectively suppressed irrespective of the change of the vehicle operating circumstance.

Abstract: A control system for an automatic transmission for a vehicle provides an enhancement in a shifting characteristic in a manually shifting mode by controlling an operating hydraulic pressure for hydraulic engage elements in an appropriate manner. In a first range from the output of a shifting command to a time point when a timer TOIPU reaches a counting-up value, or a time point when the slip rate ECL of the hydraulic engage elements exceeds a value YECLIPUS, the operating hydraulic pressure is set at a preset value depending upon the type of shifting. In a second range from the end of the first range to a time point when the timer TOIPU reaches a counting-up value, or a time point when a slip rate ECL exceeds a value TECLIPUS, and in a third range from the end of the second range to a time point when a timer TKAK reaches a counting-up value, the operating hydraulic pressure QAT is set at a value corresponding to an engine torque or a transmission input torque.

Abstract: The automatic transmission equipped with the control system of this invention is combined with a coupling for transmitting the rotation of the engine to the transmission and includes: a clutch which is applied when a forward running range is selected; a hydraulic servo which receives an oil pressure for applying the clutch; and a hydraulic control unit for controlling the oil pressure to the hydraulic servo.

Abstract: A hydraulic control system of an automatic transmission during a shift operation wherein a control pressure is controlled to selectively engage and release a plurality of frictional elements to establish a desirable shift stage comprising inertia phase detecting device for detecting a starting point of an inertia phase of the shift operation from one shift stage to another, and control pressure reducing device for gradually reducing the control pressure introduced to a frictional element to be engaged after the inertia phase is detected. The torque shock in the shift operation can be effectively reduced.

Abstract: A speed change control method for an automatic transmission is provided, which is capable of reducing a shift shock and a required shifting time period. A skip down-shift from a first shift position to a second shift position is effected by way of a third shift position which is not used in a normal shifting. If it is determined that a difference (N.sub.TM -N.sub.T) between the present turbine rotation speed N.sub.T and the synchronous rotation speed N.sub.TM for the third shift position becomes smaller than a threshold value .DELTA.N.sub.FM during the shifting from the first shift position to the third shift position, a control for releasing a friction engaging element 23, corresponding to a releasing side speed-changing element of the third shift position, is started prior to establishment of the third shift position, whereby a time period for establishing the third shift position is shortened, so that a shift shock and a required shifting time period are reduced.

Abstract: A gear shift control apparatus for use in an automatic transmission having a friction element operable on a hydraulic pressure applied thereto in an engaged and disengaged state. A shift change control is performed to change the hydraulic pressure in a manner to produce a shift change according to a predetermined shift schedule based on transmission input and output shaft speeds and engine load. A section is provided for calculating the gear ratio obtained in the automatic transmission based on the transmission input and output shaft speeds. When a change is effected to one of highest and lowest gears or when a change is effected from one of the highest and lowest gears, a transient hydraulic pressure control of changing the hydraulic pressure from the first level to the second level is performed to change the friction element state so as to effect a shift change when the calculated gear ratio reaches a reference gear ratio.

Abstract: A hydraulic control system for an automatic transmission includes a three-way duty solenoid valve which is driven at a duty rate to regulate pressure at its input port and develop a controlled pressure at its output port leading to a frictional coupling element for shifting the automatic transmission to a specific mode. The duty rate is changed depending upon driving conditions so that the controlled pressure is forced to reach a desired hydraulic pressure according to driving conditions.

Abstract: The invention relates to a method and an apparatus for controlling the output torque (M.sub.ab) of an automatic transmission 10 during the course of a gear-shifting operation in an engine-operated vehicle. The transmission 10 has at least two gears (11, 12) which can be engaged alternatively by means of clutches (16, 17). The clutches (16, 17) and the torque (M.sub.m) of the vehicle engine 14 are controlled according to at least two control sequences (SH1 to SH3, SR1 to SR3 or ZH, ZR) which can be selected as a function of instantaneously present gear-shifting conditions. According to the invention, in order to select the control sequences (SH1 to SH3, SR1 to SR3 or ZH, ZR) it is determined, as a gear-shifting condition, whether the vehicle is in an operating state with a positive clutch torque (engine traction operation) or in an operating state with a negative clutch torque (engine overrun operation).

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: Flare control is provided for downshifts in a computer controlled automatic transmission by providing an adaptive pressure term which is adjusted in response to detected flare conditions. During a downshift, engine acceleration is monitored and flare is detected when negative engine acceleration remains below a predetermined level for a predetermined duration. The level of engine acceleration indicative of flare changes with vehicle speed.

Abstract: A shift control system for an automatic transmission including frictional engagement elements to be applied by actuating a piston by an oil pressure. The shift control system comprises: a pressure regulating valve for regulating the oil pressure to be fed to the frictional engagement elements and for controlling the regulated pressure level; a shift detector for detecting a shift to be executed by feeding the oil pressure to the frictional engagement elements; a low-pressure standby unit for setting the regulated pressure level of the pressure regulator valve to such a value during a predetermined time period after the shift has been detected that the oil pressure to be fed to the frictional engagement elements moves only the piston; and a booster for controlling the regulated pressure level so that the oil pressure to be fed to the frictional engagement elements may gradually increase after lapse of the predetermined time period.

Abstract: A technique for controlling the rate of engagement of a friction element in response to a commanded change in operating range of an automatic transmission. Hydraulic pressure at a blip magnitude fills the hydraulic cylinder of a friction element. The pressure magnitude at the base of a pressure ramp and a magnitude at the top of the ramp are calibrated over a range of transmission oil temperature for each type of range change required by the vehicle operator. The calibrations minimize the length of engagement and produce a smooth engagement. Execution of an algorithm produces a high level of pressure magnitude on the basis of these calibrated values, a step down at the base of a ramp, a rate of increase during the period of engagement, and a maximum pressure at the top of the ramp.

Abstract: A hydraulic control system of the present invention is provided for improving a responsiveness to a speed change by compleating the speed chang with a torque pressure control hydraulic pressure after initiating the speed change with the drive hydraulic pressure. The hydraulic control system includes an oil pump for generating hydraulic pressure, a pressure regulating valve for regulating the hydraulic pressure to be proper pressure for reverse and drive, five friction elements which receive the hydraulic pressure for drive in accordance with operation of a manual valve, two friction elements which receive the hydraulic pressure for reverse in accordance with operation of the manual valve, first and second shift control parts having at least two shift valves, respectively, to supply the hydraulic pressure to the friction elements, and a torque control hydraulic pressure regulating part for supplying a torque control hydraulic pressure to the first and second shift control parts.