A vehicle includes a transmission having a plurality of friction elements selectively engageable to establish power flow paths within the transmission. A controller of the vehicle is programmed to, during a boost phase of a shift, command a first hydraulic boost pressure for a plurality of control loop cycles to an oncoming one of the friction elements (oncoming friction element) and subsequently command a second hydraulic boost pressure less than the first hydraulic boost pressure for only a single control loop cycle that defines an end of the boost phase to the oncoming friction element.

A method and a system of learning a pressure applied to a brake of a countershaft may include determining, when a shift condition is satisfied, whether a shifting to be performed is a power off upshift; releasing a clutch mounted between a power source and the transmission when the shifting to be performed is the power off upshift; detecting a contact duration until a speed of an input shaft of the transmission is lowered by a predetermined speed by applying a target pressure stored in a memory to the brake of the countershaft when the release of the clutch is completed; comparing the contact duration with a predetermined duration; correcting, when the contact duration is greater than the predetermined duration, the target pressure according to a difference between the contact duration and the predetermined duration; and storing and updating the corrected target pressure in the memory to apply a subsequent power on upshift.

A method for operating a drivetrain of a motor vehicle includes elevating a system pressure acting on a plurality of shift elements (A, B, C, D, E, F) when one of at least one positively locking shift element (A, F) is closed in a force-locking-free state, increasing a torque output by a drive assembly (15) and then subsequently reducing the torque output by the drive assembly (15) while the system pressure is elevated by an intervention with the drive assembly (15), and reducing the system pressure after reducing the torque output by the drive assembly (15). The one of the at least one positively locking shift element (A, F) closed in the force-locking-free state or another one of the at least one positively locking shift element (A, F) is opened while the system pressure is elevated and the torque output by the drive assembly (15) changes.

The present disclosure relates to a method for determining at least one shift parameter of a vehicle transmission (3), the vehicle transmission (3) comprising a first clutching device (8a) and a first speed ratio (9a); a second clutching device (8b) and a second speed ratio (9b); an input; and an output, wherein the input and the output of the transmission are connectable by the engaging first clutching device (8a) or the second clutching device (8b). The method comprises the steps: performing a shift by disengaging the first clutching device (8a) and/or engaging the second clutching device (8b), wherein the first clutching device (8a) stops transferring torque through the transmission at a first time point, wherein the second clutching device (8b) starts transferring torque through the transmission at a second time point, and determining the shift parameter at the first time point and/or at the second time point.

A vehicle includes a transmission having a plurality of friction elements selectively engageable to establish power flow paths within the transmission. A controller of the vehicle is programmed to, during a boost phase of a shift, command a first hydraulic boost pressure for a plurality of control loop cycles to an oncoming one of the friction elements (oncoming friction element) and subsequently command a second hydraulic boost pressure less than the first hydraulic boost pressure for only a single control loop cycle that defines an end of the boost phase to the oncoming friction element.

A transmission control device is used in an automatic transmission device including a transmission gear having friction coupling portions that are changed between a coupled state and an uncoupled state, and configuring transmission stages corresponding to a combination of the coupled state and the uncoupled state, and a hydraulic control device. The device includes: a determination unit determining a change in the transmission stage; and an output unit setting a target value of the hydraulic pressure, and outputting the target value to the hydraulic control device. In a case where one transmission stage is changed to another, the output unit increases the target value to a first value for a first friction coupling portion in the uncoupled state in the one transmission stage, thereafter, to a second value smaller than the first value and maintaining the uncoupled state, and thereafter, to a third value greater than the second value.

Systems and methods for performing a garage shift of an automatic transmission of a vehicle comprise maintaining a clutch at a first holding pressure while the transmission is in a neutral gear and a brake input signal satisfies a threshold and maintaining the clutch at a lower second holding pressure while the transmission is in the neutral gear and the brake input signal satisfies the threshold to mitigate or eliminate causing drive torque to be transferred from a torque generating system of the vehicle to its driveline via the transmission. When the brake input signal satisfies the threshold and a shift from the neutral gear to a non-neutral gear is requested, the garage shift is then executed.

Gear-changing quality of a motor vehicle having an automatic transmission in which filling pressure adaptation processes are carried out by an electronic control device by predefined activation of an oil pump and selected hydraulic switching elements is improved by inclusion of a minimum time margin between the individual adaptation processes predefined by the control device such that parallel adaptation processes are prevented.

Systems and methods for performing a garage shift of an automatic transmission of a vehicle comprise maintaining a clutch at a first holding pressure while the transmission is in a neutral gear and a brake input signal satisfies a threshold and maintaining the clutch at a lower second holding pressure while the transmission is in the neutral gear and the brake input signal satisfies the threshold to mitigate or eliminate causing drive torque to be transferred from a torque generating system of the vehicle to its driveline via the transmission. When the brake input signal satisfies the threshold and a shift from the neutral gear to a non-neutral gear is requested, the garage shift is then executed.

A shift control device for an automatic transmission includes: an engagement control unit that controls an engagement hydraulic pressure supplied to an engagement hydraulic chamber of an engagement side friction element; a hydraulic pressure detecting unit that detects the engagement hydraulic pressure; a reference setting unit that calculates a predicted value of the engagement hydraulic pressure during shifting, based on a rising characteristic of the engagement hydraulic pressure from when supply of the engagement hydraulic pressure is started to when engagement of the engagement side friction element is started, and sets the predicted value as a reference hydraulic pressure; and an engagement start detecting unit that detects an engagement start time point of the engagement side friction element, based on a difference between the hydraulic pressure detected by the hydraulic pressure detecting unit during the shifting and the reference hydraulic pressure.