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: An automatic transmission control system for selectively locking and unlocking a plurality of frictional coupling elements is provided within an automatic transmission so as to place the automatic transmission into one of various possible gears. The control locks a specific one of the frictional coupling elements with locking pressure when the automatic transmission performs a specific gear shift and unlocks it by reducing the locking pressure when causing it to perform, an opposite gear shift reverse to the specific gear shift. The locking pressure is increased by way of a relatively high level of shelf pressure during the specific gear shift and reduced by way of a relatively low level of shelf pressure during the opposite gear shift.

Abstract: An automatic transmission includes a multi-speed transmission gear mechanism having an input shaft, an output shaft and a plurality of friction coupling elements. A hydraulic control system selectively supplies a hydraulic pressure to the friction coupling elements, thereby selectively applying the friction coupling elements to cause the transmission gear mechanism to shift to a speed which is determined according to a predetermined shift pattern. The control system sets a target hydraulic pressure to be applied to the friction coupling elements according to the kind of the shift to be effected and the engine load, and, when it is detected that the transmission gear mechanism is to make a backout upshift due to reduction in the engine load, increases the target hydraulic pressure by an amount which is determined according to the throttle opening and the turbine speed.

Abstract: A control system for a torque converter includes a lock-up clutch provided in the torque converter for connecting input and output members of the torque converter directly, and a shift valve having first and second spools disposed in series in a sleeve for shifting an introduction of an engaging and releasing pressure acting on the lock-up clutch in accordance with positions of the first and second spools. The first spool is subjected to a first hydraulic pressure at one end thereof. The second spool is subjected to a second hydraulic pressure at one end thereof opposite to the one end of the first spool. The first and second spools are subjected to a third hydraulic pressure therebetween. The control system further has a first control device for controlling the first hydraulic pressure, and an adjusting valve for controlling the releasing pressure of the lock-up clutch.

Abstract: A hydraulic pressure control system for an automatic transmission includes a multiple transmission gear mechanism having a plurality of gear stages and frictional elements for switching power transmitting paths in the transmission gear mechanism, a hydraulic control mechanism for controlling engagement and disengagement of the frictional elements to establish one of said gear stages, and a line pressure control device for controlling line pressure of the hydraulic control mechanism. A speed detecting device for detects a speed of an input element of the transmission gear mechanism during shift operation of the shift gear stage in the transmission gear mechanism, and a compensation device compensates the line pressure in accordance with signal from the speed detecting device. The line pressure is compensated by a learning control to reduce a torque shock due to the shift operation.

Abstract: A control apparatus for an automatic transmission has a control unit which, when a selector lever is shifted from a forward drive gear range to a reverse gear range when the vehicle speed is not lower than a first predetermined speed, prevents the gear stage from being changed to that corresponding to the reverse gear range until the vehicle speed has fallen to a speed not greater than a second predetermined speed lower than the first predetermined speed. The control unit allows the gear stage to be changed to that corresponding to the reverse gear range if the selector lever is shifted to the reverse gear range when the vehicle speed is lower than the first predetermined speed. This control apparatus, therefore, ensures that the gear stage can be changed to that corresponding to the reverse gear range only when the driver intentionally shifts the selector lever from one of the forward drive gear ranges to the reverse gear range.

Abstract: A control system for an automatic transmission has a shift gear mechanism with a plurality of frictional elements, including a low reverse brake which is selectively actuated for switching a power transmitting path to establish a desired shift stage. A hydraulic control circuit controls supply of a hydraulic fluid to and relief of the fluid from an actuator for the frictional element. An accumulator is provided in a hydraulic passage communicated with the low reverse brake for obviating a shock as the low reverse brake is engaged. Back pressure of the accumulator is controlled when a first shift gear stage is established through the engagement of the low reverse brake. A torque shock can be suppressed when the first stage is established in an L-range.

Abstract: A shift control system for an automatic transmission including a shift gear mechanism for providing a plurality of shift stages of different speed ratios, a plurality of frictional elements to be selectively actuated for switching a power transmitting path to establish a desired shift stage, range selecting device for selecting a shift range at least between a forward and a reverse ranges through a manual operation of a driver, control device for providing the shift gear mechanism with a specific shift stage in which an input member and output member of the shift gear mechanism are rotated together with each other in the case where the reverse range is selected during a forward movement and thereafter a forward range is selected again, the specific shift stage being provided for a predetermined time period after the forward range is selected again. A double lock condition of the shift gear mechanism can be avoided.

Abstract: A fluid coupling for an automatic transmission includes an input element, an output element and a lockup clutch and is connected to a transmission mechanism. The lockup clutch can engage and disengage to operatively connect and disconnect the input element and the output element with and from each other. Further the lockup clutch can engage in slipping engagement to connect the input element and the output element in such a way as to allow the input element and the output element to rotate relative to each other to some extent. A control system causes the lockup clutch to engage in slipping engagement with a substantially fixed engaging force when the transmission mechanism upshifts while the lockup clutch is in slipping engagement, and to disengage when the transmission mechanism downshifts while the lockup clutch is in slipping engagement.

Abstract: A hydraulic control system for an automatic transmission including a shift gear mechanism having a plurality of frictional elements to be selectively actuated for switching a power transmitting path to establish a desired shift stage, a manual valve for manually selecting a shift range among a plurality of shift ranges providing predetermined shift stages, a 1-2 shift valve for making a shift operation between a first stage and a second stage, a 2-3 shift valve for making a shift operation between the second stage and a third stage, a low stage frictional element for establishing a lower shift stage, a low stage hydraulic circuit for controlling the low stage frictional element by introducing a hydraulic pressure through the manual valve and the 1-2 shift valve, a high stage frictional element for establishing a higher shift stage, a high stage hydraulic circuit for controlling the high stage frictional element by introducing a hydraulic pressure through the manual valve, the 1-2 shift valve and the 2-3 shift

Abstract: A slip control system for a torque converter of an automatic transmission includes lock-up clutch device provided in a torque converter for connecting an input and output members of the torque converter directly. A torque detecting device detects a transmitted torque introduced into the output member of the torque converter, a speed difference setting device sets a target value of a rotation speed difference between the input and output members, a pressure difference control device controls a pressure difference between a releasing chamber and an engaging chamber of the lock-up clutch device, based on a predetermined relationship between the input torque and the speed difference so as to accomplish the target value of the speed difference, and a speed difference detecting device detects an actual speed difference between the input and output members.

Abstract: An automatic transmission includes a transmission mechanism providing a high speed gear ratio and a low speed gear ratio, a hydraulic control circuit having a cutback device settable in one of a cutback execution state and a cutback suspension state, a primary control device for setting the cutback device in the cutback execution state when the gear ratio is a low speed, and setting the cutback device in the cutback suspension state when the gear ratio is a high speed, a secondary control device for setting the cutback device in the cutback suspension state when the gear ratio is a high speed, and a selection device for selecting the primary control device when the oil temperature is lower than a predetermined value, and selecting the secondary control device when the oil temperature is higher than the predetermined value.

Abstract: An oil pressure control system for an automatic transmission employed in a vehicle comprises a device for producing line pressure, a device for supplying engaging friction elements in the automatic transmission with operating oil pressure obtained from the line pressure, a device for determining a pressure control variable based on operating condition of an engine with which the automatic transmission is coupled, a device for determining a supplemental control variable based on a duration of speed change or a state of speed change in the automatic transmission, a device for revising the supplemental control variable in accordance with the operating condition of the engine to produce a revised supplemental control variable, a device for revising the pressure control variable in accordance with the revised supplemental control variable to produce a revised pressure control variable, and a control device operative to control the line pressure in accordance with the revised pressure control variable when a specif

Abstract: A line pressure controller deduces the completion of the speed change operation and sets the line pressure to a low level during the confirmation of the completion. If the acceleration is detected during the confirmation time period, the control device raises the line pressure up to an original level so as to prevent slip of the torque converter.

Abstract: A hydraulic pressure control system for an automatic transmission includes a torque converter, a multiple transmission gear mechanism having a plurality of gear stages and frictional elements for switching power transmitting paths in the transmission gear mechanism, a hydraulic control mechanism for controlling engagement and disengagement of the frictional elements to establish one of the gear stages, and a line pressure control device for controlling line pressure of the hydraulic control mechanism in accordance with a vehicle operating condition. An engine torque detecting device detects an engine output torque, and a turbine speed detecting device detects a turbine speed of the torque converter. A shift condition detecting device detects a shift-up operation and a shift-down operation in the transmission, and the line pressure control device controls the line pressure in accordance with the engine torque in the shift-up operation and the turbine speed in the shift-down operation.

Abstract: A line pressure control system for an automatic transmission, including a multiple shift stage transmission gear mechanism having a plurality of power transmitting paths of different speed ratios, has a line pressure control device for controlling a line pressure for frictional elements of the transmission gear mechanism associated with each other to establish a desirable shift gear stage. A shift period detector detects a time period for a shift operation, accomplished in terms of operation of the frictional elements controlled by the line pressure. A first compensating device controls the line pressure in terms of a learing control in a manner such that the time period for the shift operation is controlled to a target value. An abnormality detecting device detects an abrupt change, such as a turbine speed rise or, depression, or a driving torque depression in an operating condition of the transmission.

Abstract: An automatic transmission includes transmission mechanism having a friction coupling member for enabling engine brake, and a hydraulic control circuit having a pressure regulator valve for feeding a coupling pressure to the friction coupling member and a cutback valve for reducing the coupling pressure. This automatic transmission further has a cutback valve control device for suspending the cutback in a particular gear ratio in the engine brake enable range. Accordingly, in the engine brake enable range which requires a higher coupling pressure, a sufficient coupling pressure can be assured by suspending the cutback.

Abstract: An automatic transmission has a transmission gear mechanism and a plurality of friction coupling members which are applied or released by hydraulic pressures applied thereto under the control of a hydraulic control system. The control system includes a hydraulic control circuit which controls the hydraulic pressure fed to or discharged from the respective friction coupling member, thereby changing the condition of application of the friction coupling members and causing the automatic transmission to shift. The plurality of friction coupling members includes first and second friction coupling members the conditions of application of which are changed during gear shifting from a first predetermined gear speed to a second predetermined gear speed. The first and second friction coupling members are fed with the hydraulic pressure respectively through first and second hydraulic passages.

Abstract: A control system for an automatic transmission employed in a vehicle comprises first and second engaging friction elements provided in the automatic transmission for giving rise to speed change, an operating oil pressure control device for applying operating oil pressure to each of the first and second engaging friction elements in accordance with a predetermined control characteristic so as to change engaging conditions of the first and second engaging friction elements, an information detector for obtaining information of the operating condition of the automatic transmission, and a timing control device for causing the operating oil pressure control device to be operative to adjust a time interval from a time at which the first engaging friction element is changed in its engaging condition to a later time at which the second engaging friction element is changed in its engaging condition in accordance with the information obtained from the information detector, with the information being the revolving speed

Abstract: A lockup torque converter of an automatic transmission for an automotive vehicle consists of an impeller connected to an engine, a turbine connected to the automatic transmission, and a lockup clutch disposed between first and second pressure chambers formed in a housing of said lockup torque converter for locking and releasing the lockup torque converter. A control unit supplies a hydraulic pressure into the first pressure chamber and withdraw a hydraulic pressure chamber from the second pressure chamber or reversely so as to actuate the lockup clutch to lock or unlock the lockup torque converter, respectively. A pressure regulating unit develops a pressure difference between the first and second pressure chambers when the shifting of the automatic transmission is detected, thereby causing the lockup clutch to allow the lockup torque converter to slip in accordance with certain conditions.