Systems and methods for operating a hybrid powertrain that includes an engine and a motor/generator are described. The systems and methods adjust torque converter clutch opening responsive to whether or not a motor/generator is available to provide a negative torque to a driveline. Further, the motor/generator and the vehicle's engine are operated to provide a desired amount of driveline braking.

A lockup disengagement control device for an automatic transmission including a torque converter including a lockup clutch, and a lockup control section, the lockup disengagement control device includes: when a brake is operated from a brake OFF to a brake ON during a coast traveling in an engagement state of the lockup clutch, the lockup control section being configured to sense an initial deceleration by the brake ON operation, and to set a lockup release vehicle speed to be higher as an absolute value of the initial deceleration is greater, and when a vehicle speed is sensed to be equal to or smaller than the set lockup release vehicle speed in a middle of a brake deceleration scene by the brake ON operation, the lockup control section being configured to disengage the lockup clutch.

A control device for a lock-up clutch includes a control unit, an abnormality determination unit, a release control unit and a prohibition unit. The control unit is configured to control an engagement state of a lock-up clutch, and to perform a slip lock-up control by performing a feedback control of an engagement hydraulic pressure to be a first slip amount during coasting. The abnormality determination unit is configured to determine an abnormality when a state continues with a slip amount being equal to or greater than a second slip amount. The release control unit is configured to release the lock-up clutch when the abnormality is determined. The prohibition unit is configured to allow the control unit to raise the engagement hydraulic pressure by a prescribed pressure, and to prohibit determination by the abnormality determination unit, when the transmission ratio is downshifted during coasting while the slip lock-up control is performed.

A torque converter includes a case and a bypass clutch having a plate rotationally fixed to the case and a friction disk having a friction material configured to engage with the plate to rotationally couple the friction disk to the plate when the bypass clutch is engaged. The friction disk includes a first circumferential connection surface having a plurality of alternating convex and concave arcuate segments. A drive plate includes a second circumferential connection surface having a plurality of alternating convex and concave arcuate segments. The first and second connection surfaces are in meshing engagement with the convex segments of the friction disk meshing with the concave segments of the drive plate and with the concave segments of the friction disk meshing with the convex segments of the drive plate.

A torque converter includes a case and a bypass clutch having a plate rotationally fixed to the case and a friction disk having a friction material configured to engage with the plate to rotationally couple the friction disk to the plate when the bypass clutch is engaged. The friction disk includes a first circumferential connection surface having a plurality of alternating convex and concave arcuate segments. A drive plate includes a second circumferential connection surface having a plurality of alternating convex and concave arcuate segments. The first and second connection surfaces are in meshing engagement with the convex segments of the friction disk meshing with the concave segments of the drive plate and with the concave segments of the friction disk meshing with the convex segments of the drive plate.

A lockup disengagement control device for an automatic transmission including a torque converter including a lockup clutch, and a lockup control section, the lockup disengagement control device includes: when a brake is operated from a brake OFF to a brake ON during a coast traveling in an engagement state of the lockup clutch, the lockup control section being configured to sense an initial deceleration by the brake ON operation, and to set a lockup release vehicle speed to be higher as an absolute value of the initial deceleration is greater, and when a vehicle speed is sensed to be equal to or smaller than the set lockup release vehicle speed in a middle of a brake deceleration scene by the brake ON operation, the lockup control section being configured to disengage the lockup clutch.

A control device for an automatic transmission of a vehicle includes a shift control section including; a deceleration state judging section configured to judge whether a deceleration of the vehicle is a gentle deceleration state or a sudden deceleration state, and a downshift control section configured to command a plural stage downshift to downshift from a current shift stage of the automatic shift mechanism to a target shift stage that is lower than the current shift stage by two stages or more when the deceleration state judging section judges the sudden deceleration state.

A control device for a lock-up clutch includes a control unit, an abnormality determination unit, a release control unit and a prohibition unit. The control unit is configured to control an engagement state of a lock-up clutch, and to perform a slip lock-up control by performing a feedback control of an engagement hydraulic pressure to be a first slip amount during coasting. The abnormality determination unit is configured to determine an abnormality when a state continues with a slip amount being equal to or greater than a second slip amount. The release control unit is configured to release the lock-up clutch when the abnormality is determined. The prohibition unit is configured to allow the control unit to raise the engagement hydraulic pressure by a prescribed pressure, and to prohibit determination by the abnormality determination unit, when the transmission ratio is downshifted during coasting while the slip lock-up control is performed.

A control device for an automatic transmission of a vehicle includes a shift control section including; a deceleration state judging section configured to judge whether a deceleration of the vehicle is a gentle deceleration state or a sudden deceleration state, and a downshift control section configured to command a plural stage downshift to downshift from a current shift stage of the automatic shift mechanism to a target shift stage that is lower than the current shift stage by two stages or more when the deceleration state judging section judges the sudden deceleration state.

A vehicle includes a powertrain and a controller. The powertrain includes a transmission torque converter having a bypass clutch disposed between an electric machine and a drive wheel. The controller is programmed to adjust a closed-state torque capacity of the bypass clutch according and in proportion to the greater in absolute value of a negative impeller torque command to the torque converter and a negative regenerative braking torque request.