Abstract: A control apparatus for an automatic transmission having a set of frictional engagement elements arranged to be selectively engaged or disengaged in shift-up operation of the transmission, and a shift timing valve arranged to be switched over by hydraulic pilot pressure applied there-to under control of a solenoid valve for switching over discharge of fluid under pressure from one of the frictional engagement elements to be disengaged in the shift-up operation from a slow-drain condition to a quick-drain condition. The control apparatus is designed to detect a drive torque of a vehicle engine, to determine a timing period for energization of the solenoid valve in the shift-up operation in accordance with the drive torque of the vehicle engine, to maintain the solenoid valve in its deenergized condition during the timing period, and to energize the solenoid valve upon lapse of the timing period.

Abstract: During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while a higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nt)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)'.

Abstract: During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nia)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)'.

Abstract: An automotive automatic transmission has a hydraulically operated clutch device and an electronic control unit. The clutch device includes drive and driven clutch plates and a piston for pressing the drive and driven clutch plates to establish an engagement therebetween when an oil chamber for the piston is fed with a certain amount of fluid. In order to control the clutch device, the following steps are employed, which are (a) issuing a first instruction signal to the clutch device; (b) feeding the oil chamber with the fluid by an amount which is sufficient for moving the piston from a rest position to a critical position which is ready for effecting the actual pressure against the drive and driven clutch plates; (c) issuing a second instruction signal to the clutch device; and (d) increasing the hydraulic pressure in the oil chamber to cause the piston to instantly establish the engagement between the drive and driven clutch plates.

Abstract: An electrohydraulic control system for an automatic transmission includes planetary gearsets, clutch and brakes that control the condition of the gear components, hydraulically actuated solenoid control valves, electronic sensors connected to a microprocessor, a gear selector mechanism and an overdrive cancel switch. The extent to which a gear ratio change is completed, as represented by the ratio of the current operating gear ratio and the gear ratio associated with gear ratio at the completion of the gear shift, is used as a variable in algorithms executed by the microprocessor to schedule change in state of solenoid operated valve. The state determines the engaged and disengaged condition of friction elements that produce the gear shift.

Abstract: In a control system for an automotive automatic transmission having a friction element powered by a line pressure, a gear ratio provided by the transmission is measured. An inertial phase keeping time is measured, which is the time for which the transmission assumes an inertial phase. A line pressure adjuster is employed to adjust the line pressure in a manner to harmonize the inertial phase keeping time with a predetermined time. An inertial phase starting time is measured, which is the time elapsed until the inertial phase of the transmission starts. A line pressure increasing device is employed for increasing the line pressure irrespective of condition of the line pressure adjuster when the inertial phase starting time exceeds a first given time. An inhibitor is employed to suppress the operation of the line pressure increasing device in case wherein even when the inertial phase starting time exceeds a second given time longer than the first predetermined time, the change of the gear ratio does not occur.

Abstract: A method is provided for the control of servo hydraulic pressure in an automatic transmission. Servo hydraulic pressure is adapted to engage or release first and second frictional engagement elements arranged in such a relationship that, upon shifting from one particular speed stage to another, one of the first and second frictional engagement elements is released while the other is engaged. The servo hydraulic pressure, engaging one frictional engagement element, is linearly lowered in a torque phase during a shift so it releases the one frictional engagement element, responsive to a rise in the servo hydraulic pressure to the frictional engagement element to be engaged, to maintain an inversely proportional relationship between the servo hydraulic pressure being raised and that being released.

Abstract: A process is described for controlling the actuating pressure in a control element (shift element) of an electrohydraulically controlled transmission of a motor vehicle during a change of the gear position. In the case of downshifts in the coasting operation, the hydraulic pressure in the transmission is preferably increased with the initiating of the shifting by way of the pressure control valve in a time-limited manner. Starting from a presettable or preset basic value, the amount of this filling pulse is automatically and in steps for each control operation in the course of the operation of the transmission adapted to a target value in such a manner that an input rotational speed of the transmission or a rotational speed of a driving engine connected in front of the transmission follows a predetermined sequence of movements.

Abstract: A particular engine control system is used with an engine equipped with an automatic transmission. The automatic transmission is changeable between an economy operation mode, in which the automatic transmission is placed more frequently in higher gears so as to create a travel mode giving priority to fuel economy, and a power operation mode, in which the automatic transmission is placed more frequently in lower gears so as to create a travel mode giving priority to powerful running. The system controls the engine so as to provide a gentle increase in engine output in the economy mode.

Abstract: A control system is provided for a vehicle regulating engine speed during shifts so as to reduce driveline torque and shift shock. The control system includes separate microprocessor based engine and transmission controllers which communicate via a data link. When a shift is initiated, the transmission controller delays a period of time sufficient for the transmission to disengage the old gear ratio and then produces a CTSSPEED signal. The transmission controller continues to produce the CTSSPEED signal for a second period of time which corresponds to the time required for the transmission to engage the new gear ratio.The engine controller receives the desired engine speed signal and regulates engine speed into correspondence with the desired speed. During upshifts, the CTSSPEED signal is set to a speed which is a predetermined amount above the synchronization speed of the new gear for an upshift.

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.