Abstract: Automatic transmission 1 includes second friction plates 17 connecting a second drum 27 to a second hub 37, a second engagement hydraulic chamber 67, a second centrifugal balance chamber 77, and a second piston 47 engaging and disengaging the second friction plates 17. The second centrifugal balance chamber 77 overlaps the second friction plates 17 in the axial direction in the automatic transmission 1. The automatic transmission 1 further includes a second oil passage 9 for discharging hydraulic oil in the second centrifugal balance chamber 77 to a position not overlapping the second friction plates 17 in the axial direction.

Abstract: Automatic transmission 1 includes second friction plates 17 connecting a second drum 27 to a second hub 37, a second engagement hydraulic chamber 67, a second centrifugal balance chamber 77, and a second piston 47 engaging and disengaging the second friction plates 17. The second centrifugal balance chamber 77 overlaps the second friction plates 17 in the axial direction in the automatic transmission 1. The automatic transmission 1 further includes a second oil passage 9 for discharging hydraulic oil in the second centrifugal balance chamber 77 to a position not overlapping the second friction plates 17 in the axial direction.

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: 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: 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: A shift control system of an automatic transmission includes a first element which is to be released in a shift operation, a second element which is to be engaged in the shift operation, and a target shift time set section for setting a target time period of the shift operation needed for releasing the first frictional element and engaging the second frictional element. A shift time calculation section is provided for obtaining an actual time period of the shift operation needed for releasing the first frictional element and engaging the second frictional element, and a releasing pressure control section is provided for receiving output of the target shift time set section and the shift time calculation section for controlling a releasing pressure of the first frictional element in the shift operation based on the difference between the target and actual time periods of the shift operation.

Abstract: An automatic transmission control system has a plurality of frictional coupling elements within an automatic transmission which are selectively locked and unlocked in a particular way to place the automatic transmission into any desired gear in various ranges. Two specific frictional coupling elements, such as a low/reverse brake and a 3/4 clutch, may potentially cause mechanical locking of the automatic transmission when they are locked simultaneously. The automatic transmission control system, however, includes a first valve for connecting and disconnecting a supply of hydraulic pressure to the low/reverse frictional coupling element to lock and unlock the low/reverse frictional coupling element in low speed and reverse ranges, and a second valve for connecting and disconnecting a supply of hydraulic pressure to the 3/4 frictional coupling element to lock and unlock the 3/4 frictional coupling element.

Abstract: A multiple stage automatic transmission includes a main transmission mechanism, a sub-transmission mechanism connected with the main transmission mechanism to for introduction of a torque therefrom, and a frictional element connected with the sub-transmission. The engaging force of the frictional element is changed at least by two steps in accordance with a shift mode without changing a hydraulic pressure applied for actuating the frictional element. A shift shock, therefore, can be obviated.

Abstract: A control apparatus for an engine and an automatic transmission controls a starting timing, a terminating timing, or methods of torque reduction of the engine during gear shifts. Using stored information such as a turbine speed signal, a gear shift signal, a degree to which a throttle valve is opened, a vehicle speed, an engine speed and so on, the control apparatus calculates an appropriate torque reduction which is performed by either retarding ignition timing or cutting fuel supplied to fuel injection valves. According to one embodiment of the invention, by detecting a variation ratio or differential value of turbine speed, a period of the torque reduction is started, ended, and kept within a proper timing. According to another embodiment of the invention, based on a "chasing" state of an input torque of the transmission against the variation of engine load, the timing of torque reduction is changed.

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 automatic transmission includes a first transmission mechanism having a first shaft connectable to an output shaft of an engine, a second transmission mechanism associated with the first transmission mechanism, and having a second shaft in parallel with the first shaft, the second transmission mechanism being adapted for changing the torque speed of the first shaft, a hydraulic housing for accommodating a hydraulic control device for the second transmission mechanism, the second hydraulic housing being arranged above the second transmission mechanism, and an axis of the second shaft being positioned on either the same horizontal plane as an axis of the first shaft or a horizontal plane above the axis of the first shaft.

Abstract: A hydraulic control system for controlling an automatic transmission includes a regulating valve which reduces a line pressure in accordance with a control pressure, provided in accordance with vehicle driving conditions, to provide a coupling pressure for coupling a specific one of frictional coupling elements of the automatic transmission. The regulating valve is enabled to provide the coupling pressure independently from the control pressure when a coupling pressure for another frictional coupling element higher than a specified level.

Abstract: A particular shift control system is provided for an automatic transmission having a primary transmission, changeable to at least three primary gear ratios, and a secondary transmission, changeable to at least two secondary gear ratios. The primary and secondary transmissions combine to shift the automatic transmission to a plurality of forward speeds. The control system monitors the progression of change in the primary transmission gear ratio. In a specific automotive drive condition, the primary transmission changes from one primary gear ratio to another primary gear ratio via an intermediate primary gear ratio between the two primary gear ratios. This produces an increase or decrease in a primary gear ratio. At the same time, the secondary transmission decreases or increases, respectively, a secondary gear ratio so as to shift the automatic transmission from one forward speed to another, skipping an intermediate speed between the two forward speeds.

Abstract: A control system controls a second to third gear shift of an automatic transmission in an advantageous way. The transmission has a 3-4 clutch, which is locked under hydraulic pressure, and a 2-3 brake provided with a lock pressure chamber and an unlock pressure chamber. The 2-3 brake is locked when a hydraulic pressure is developed in the lock pressure chamber only and is unlocked when a fluid pressure is developed in the unlock pressure chamber and when a hydraulic pressure is released from both the lock pressure chamber and the unlock pressure chamber. Hydraulic pressure is released from the lock pressure chamber so as to unlock the 2-4 brake only when a second to third gear shift is needed for the first time after engine ignition simultaneously with application of pressure to the 3-4 clutch so as to lock the 3-4 clutch.

Abstract: A control apparatus for an engine and an automatic transmission controls a starting timing, a terminating timing, or methods of torque reduction of the engine during gear shifts. Using stored information such as a turbine speed signal, a gear shift signal, a degree to which a throttle valve is opened, a vehicle speed, an engine speed and so on, the control apparatus calculates an appropriate torque reduction which is performed by either retarding ignition timing or cutting fuel supplied to fuel injection valves. According to one embodiment of the invention, by detecting a variation ratio or differential value of turbine speed, a period of the torque reduction is started, ended, and kept within a proper timing. According to another embodiment of the invention, based on a "chasing" state of an input torque of the transmission against the variation of engine load, the timing of torque reduction is changed.

Abstract: The control system for an automatic transmission shifts the main transmission simultaneously with the auxiliary transmission at the time of a particular shift. At this time, a target gear ratio progress value of the auxiliary transmission is set for a gear ratio progress value indicative of a shift progress state of the main transmission. The main transmission is arranged so as to finish the shift control within a given target period of time, and the auxiliary transmission is arranged to implement the shift control by the feedback control so as to follow the target gear ratio progress value. The shift control of the auxiliary transmission is corrected by the learning control on the basis of a deviation between the target gear ratio progress value and the actual gear ratio progress value.

Abstract: A control system for an automatic transmission including a main transmission and a subtransmission whose shift operation is carried out by hydraulically. The control system comprises a first device for adjusting a gear ratio advance of the main transmission, the gear ratio advance corresponding to a gear ratio change during the shift operation, a second device for adjusting a gear ratio advance of the subtransmission, the gear ratio advance corresponding to a gear ratio change during the shift operation, and a device for controlling the frist adjusting device and the second adjusting device during concurrent shift operations of the main transmission and the subtransmission so that the gear ratio advances of the main transmission and the subtransmission become equal to respective predetermined target gear ratio advances.

Abstract: An automatic transmission has a sub-transmission and a main transmission disposed on the engine side and on the driven wheel side in series. The sub-transmission and the main transmission are each comprised of a planetary gear mechanism so as to allow the sub-transmission to assume two speed range modes including low and high speed ranges and the main transmission to assume three speed range modes including low, intermediate and high speed ranges. When the automatic transmission is downshifted from the fifth to the third speed range mode, both of the sub-transmission and the main transmission are downshifted. In this case, the sub-transmission is downshifted from the high speed range to the low speed range. While the main transmission is downshifted from the high speed range to the intermediate speed range. In the downshifting from the fifth to the third speed range, a gear ratio of the sub-transmission between prior to and subsequent to the shift is set to be smaller than that of the main transmission.