Methods and systems are provided for an electric drivetrain. In one example, the electric drivetrain system includes a first and a second electric motor-generator rotationally coupled to a planetary assembly that is rotationally coupled to a drive axle via an output gear. The system further includes a controller that is configured to, during a first operating condition, operate each of the first and second electric motor-generators in a motor mode or a generator mode and hold the output gear at a zero speed.

A control apparatus for a vehicle drive-force transmitting apparatus that includes a gear mechanism and a continuously-variable transmission mechanism. The control apparatus determines whether there is a lower-gear-ratio setting request requesting a target gear ratio of the continuously-variable transmission mechanism to be set to a lower gear ratio that is lower than a highest gear ratio of the continuously-variable transmission mechanism. When it is determined that there is not a detection accuracy of a rotational speed of an output rotary member of the drive-force transmitting apparatus, the control apparatus sets the target gear ratio to the lower gear ratio if it is determined that there is the lower-gear-ratio setting request, and sets the target gear ratio to the highest gear ratio if it is determined that there is not the lower-gear-ratio setting request.

A controller forms a control device for a vehicle equipped with an automatic transmission including a parking lock module. If a power transmission clutch is engaged erroneously (S2) on the basis of electrical abnormality in a solenoid part while an N range is selected (S1), the controller forcibly turns off the solenoid part to forcibly disengage the power transmission clutch (S3). Further, if a vehicle speed is equal to or less than a predetermined vehicle speed (S4), the controller applies a parking lock using the parking lock module (S5).

An automatic transmission includes a park rod adapted to non-rotatably lock an output shaft of the automatic transmission, an actuator adapted to drive the park rod, and an ATCU adapted to drive the actuator when a setting range of the automatic transmission is set into a P range. In a situation where an accelerator pedal is pressed on a climbing slope, driving force and gradient resistance are balanced, and a vehicle is stopped, the ATCU does not set the setting range of the automatic transmission into the P range even when a shifter is operated into the P range.

A transmission is between a drive aggregate and a drive output of a vehicle drivetrain and includes a hydrodynamic starting element and a powershiftable main transmission having a plurality of forward gears and at least one reversing gear. The main transmission has frictional shifting elements, where in each gear a first number of shifting elements are closed and a second number of shifting elements are open. A downstream range group is connected downstream from the main transmission and has at least one interlocking shifting element that can be shifted between first a second driving ranges. With the drive aggregate running, the motor vehicle at a standstill or nearly so, and the main transmission in neutral, a shift request to change the downstream range group is received. The shifting elements of a reversing gear are at least partially closed, and the driving range of the downstream range group is then changed.

A method for operating a dual clutch transmission of a motor vehicle having a first partial transmission, a second partial transmission, and a transmission output shaft common to the partial transmissions and drivable both by the first partial transmission and by the second partial transmission, in which the dual clutch transmission is in a parking lock state in which two gears of one of the partial transmissions are engaged simultaneously. The following steps are carried out to exit the parking lock state: Introducing a torque caused by a drive element of the motor vehicle via the transmission output shaft common to the one partial transmissions into the one and/or other partial transmission while the gears of the partial transmission are engaged; and disengaging at least one of the gears of the one partial transmission engaged simultaneously in step a).

A system for enabling an engine to be safely cranked may include a single cranking relay configured to enable the engine to be cranked when activated, a contactless angle sensor for detecting a gear state of a transmission connected with the engine, and a controller. The controller may be configured to check the gear state of the transmission detected by the angle sensor and may allow for activation of the cranking relay when the gear state of the transmission is at one of a Neutral gear state or a Park gear state.

A method of controlling an automatic transmission mounted on a vehicle having an automatic engine stop mechanism for automatically stopping and restarting an engine, is provided. The transmission includes a piston having first and second surfaces, friction plates, engaging and disengaging hydraulic pressure chambers, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, first and second oil paths communicating the control valve with the chambers, a pressure reducing valve for preventing pressure of the disengaging chamber from exceeding a given set pressure, a hydraulic pressure supply device for supplying pressure to the control valve in the automatic stop state, and a mechanical oil pump for supplying pressure to the control valve while the engine is driving, the second surface having a larger pressure receiving area than the first surface. The method includes adjusting the set pressure to be lower in the automatic stop state than while driving.

In gear-shift control apparatus and method for a vehicular transmission, a variator which is interposed between an engine and driving wheels and which is capable of modifying a gear (speed) ratio continuously; a sub transmission which is installed in series with the variator and which is capable of switching a plurality of gear-shift stages through a replacement of engagement elements; and a transmission controller which performs a gear ratio control for the variator and a gear-shift stage control for the sub transmission are installed. During a deceleration through a second speed stage of the sub transmission, when the variator is a state in which the variator is at a lowest gear (speed) ratio, a down-shift in which the sub transmission is forced to perform the gear-shift from a second speed stage to a first speed stage, with the variator maintained at the lowest gear (speed) ratio.

A method of adjusting and using operating parameters of a transmission of a vehicle may include accessing a stored list of clutch parameters, performing a dynamic condition procedure while the vehicle is driven to revise minimum on-coming apply pressure for each friction element based on a sensed performance of an element within the vehicle powertrain, storing the modified minimum on-coming apply pressures, and operating the vehicle. A related transmission control device operates a transmission using parameters obtained during a dynamic condition procedure.