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 control system for a lock-up clutch employed in a lock-up torque converter for an automotive automatic transmission includes a lock-up control valve for controlling a lock-up of the lock-up clutch, a duty-ratio controlled lock-up solenoid, and a control unit for quickly releasing the lock-up clutch at a higher speed based on a controlled duty ratio, when the change-speed operation is performed simultaneously with the lock-up clutch releasing operation.

Abstract: A control system for a lockup clutch measures an actual time required from start of engagement of the lockup clutch until completion of engagement of the lockup clutch, and sets a reference time required from start of engagement of the lockup clutch until completion of engagement of the lockup clutch. The system modifies a change rate of the duty ratio to the time so as to reduce a difference between the actual time and the reference time.

Abstract: There is disclosed a line pressure control for an automatic transmission of an automotive vehicle wherein the automatic transmission is drivingly coupled with the engine and transmits the engine torque by a hydraulically actuable coupling which is actuable by a pressurized hydraulic fluid which is as high as the line pressure. According to this control, a predetermined pattern of variation of the pressurized hydraulic fluid is changed to a second pattern upon detecting the occurrence of a change in an engine load beyond a predetermined degree, and the pressurized hydraulic fluid follows the second pattern temporarily, i.e., for a period of time.

Abstract: An apparatus for operating a lockup clutch to provide a controlled degree of slip between the impeller and the turbine in an automatic transmission. A gear ratio is calculated from a relationship specifying the gear ratio as a function of selected gear change mode and time elapsed after the selected gear change mode starts. The calculated gear ratio is used, along with the transmission output shaft speed to calculate a speed of rotation of the turbine. The lockup clutch is operated in a slip lockup mode to bring a difference between the engine and turbine speeds to a predetermined value. Engine speed changes are monitored to measure a time interval required for the gear change of the selected mode. The relationship is modified to correct the gear ratio stored for the selected gear change mode based upon the measured time interval.

Abstract: In order to reduce a select shock of an automatic transmission, a measure is employed, which comprises a first device for detecting the selection of a drive range from a neutral range; a second device for detecting the starting of engaging movement of a hydraulically operated friction element for the drive range; a third device for controlling a hydraulic pressure applied to the friction element; a fourth device for causing the third device to raise the hydraulic pressure to a higher level from the time when the range selection is carried out to the time when the second device detects the starting of engaging movement and lower the hydraulic pressure to a lower level after the detection by the second device; a fifth device for producing an instruction signal when a predetermined time passes after the drive range detection by the first device; and a sixth device for causing the third device to lower the hydraulic pressure to the lower level upon issuance of the instruction signal irrespective of any detection

Abstract: An existing maximum engine speed during the upshift of a transmission at the time when the engine load is higher than a predetermined level is detected. The existing maximum engine speed is compared with a reference maximum engine speed to correct an engine speed based upshift characteristic line.

Abstract: A control system for controlling an automatic transmission on a motor vehicle is disclosed. The control system comprises a vehicle speed sensor for detecting the vehicle speed; an engine load sensor for detecting the engine load; a brake pedal depression degree sensor for detecting the degree by which the brake pedal is depressed; and a downshift control device for forcing the transmission to carry out a downshift when the vehicle speed is lower than a predetermined speed, the engine load is lower than a predetermined load and the brake pedal depression degree is greater than a predetermined depression degree. The control system further comprises a changing device changes the predetermined depression degree in accordance with the condition which the transmission assumes.

Abstract: An exhaust braking control apparatus includes a control valve situated for movement within an engine exhaust passage to control exhaust gas flow from the engine to the atmosphere. A control unit is provided to set the control valve at a position to provide a continuously variable degree of exhaust braking effect based upon vehicle operating conditions. In another aspect, the control unit is arranged to move the control valve in a closing direction to provide an exhaust braking effect only under specified vehicle operating conditions.

Abstract: A lock-up clutch control during a gear shifting is disclosed. A ratio of an input revolution speed of an automatic transmission to an output revolution speed thereof is used to determine whether the gear shifting is in progress. If this is the case, the lock-up clutch is released. A timer is provided which starts measuring time after occurrence of a command for such gear shifting. If the length of time becomes greater than a predetermined value, the lock-up clutch is released.

Abstract: An engine brake control system generally engages an overrun clutch in overall throttle valve open angle range at operational ranges for effecting engine brake. The control system is responsive to variation of selected operational range from a high transmission speed ratio range for automatic speed ratio selection to the engine braking range for establishing engagement of the overrun clutch with a predetermined lag time. The predetermined lag time is adjusted depending upon the vehicle driving condition.

Abstract: A method and system for processing an output signal of a throttle opening degree sensor is disclosed. According to this signal processing, a predetermined correction of the output signal of the throttle sensor is prohibited when a rate of change of the output signal fails to be less than a predetermined value.

Abstract: A control system for an automatic power transmission for an automotive vehicle performs line pressure control, shift control, lock-up control, engine brake clutch control, and so forth, on the basis of preselected engine control, parameters including a throttle valve open angle monitored by a throttle angle sensor. The control system is designed to detect failure of the throttle angle sensor or abnormality of the output signal of the throttle angle sensor to perform in a fail-safe mode of operation. In the fail-safe mode of operation, respective ones of a plurality of mutually distinct back-up signals serve as replacement of the throttle angle sensor signal. Each of the back-up signals is adapted to one of line pressure control, shift control, lock-up control, and engine braking clutch control for maintaining acceptable drivability of the vehicle.

Abstract: A timing control for an overrunning clutch is disclosed. A revolution speed ratio of an input shaft revolution speed to an output shaft revolution speed is employed as a parameter reflecting the progress in a downshift initiated by a select operation to an engine braking range. When this ratio reaches a target value, a control unit generates an ON signal. In response to this ON signal, an overrunning clutch solenoid is energized to engage the overrunning clutch.

Abstract: In order to prevent the line pressure level from being adjusted to abnormally low levels during the operation of a high load device such as an air conditioner compressor, oil pump and the like, which device consumes energy output from the engine and reduces the amount of torque which is supplied to the input shaft of the transmission, the adaptive correction of the line pressure level is inhibited while the high load device or devices are sensed as being in use.

Abstract: An engine braking control system for automotive automatic transmissions, comprises shift solenoids activated for executing a down-shift operation by selectively engaging or releasing frictional elements of a gear train, in response to engine braking requirements, sensors for monitoring a vehicle speed, an opening angle of a throttle valve, a depression amount of a brake-pedal, and a controller for controlling the down-shift operation on the basis of the signals from the sensors. The controller activates the shift solenoids for executing the down-shift operation only when the throttle opening angle is equal to or less than a predetermined threshold throttle opening angle, the brake-pedal depression amount exceeds a predetermined threshold depression amount and the vehicle speed is less than a predetermined threshold vehicle speed.

Abstract: A shift control system controls a shifting transition period in order to obtain an optimal shift feeling. The shifting control system sets a shifting transition period which is variable depending upon a vehicular driving condition so that an optimum transmission speed ratio shifting transition in view of a required magnitude of energy absorption can be achieved without causing a substantial shift shock. Preferably, the vehicular driving condition includes vehicle speed which controls which transmission speed ratio is selected for comparison with the current transmission speed ratio to derive a target transition period. The shifting transition period is then adjusted toward the target transition period for smooth shifting.

Abstract: A shift control system is provided with first and second down shifting criteria. The first down shifting criterion is set at a higher vehicle speed than that of the second down shifting criterion so that actual down shifting operations take place at a higher vehicle speed for the first criterion than for the second down shifting criterion. The shift control system is responsive to a manually entered down shift command for selecting the first down shifting criterion and maintaining the first down shifting criterion for a predetermined period of time, and subsequently selecting the second down shifting criterion after expiration of the predetermined time period.