Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, gears of a transmission may be unlocked from layshafts while an engine is stopped to conserve energy. Alternatively, the gears may be locked and unlocked from layshafts in response to vehicle operating conditions while the engine is stopped to improve driveline response.

A method for turning off an internal combustion engine (ICE) where a clutch arrangement has first and second clutches that respectively couple the ICE to first and second input shafts of a transmission. The input shafts are drivingly connected to first and second sets of gears, respectively. The sets of gears are connected to an output shaft of the transmission. The method includes: controlling the ICE in an idling state when the vehicle is in standstill, wherein the clutches are in open positions; engaging the first input shaft with a first pre-selected gear, and engaging the second input shaft with a second pre-selected gear; initiating an engine turning off command; stopping the ICE by at least partly closing the clutches for simultaneously introducing torque transfer to the clutches into a transmission tie-up state for a controlled engine stop, wherein engine inertia of the ICE is captured in the clutches.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, torque output from the engine and the electric machine is adjusted to provide controlled vehicle side slip during cornering by a vehicle.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, gears of a transmission may be unlocked from layshafts while an engine is stopped to conserve energy. Alternatively, the gears may be locked and unlocked from layshafts in response to vehicle operating conditions while the engine is stopped to improve driveline response.

Methods and systems are provided for starting an engine in a hybrid vehicle. In one example, a method includes cranking an engine of the vehicle by controlling a capacity of a clutch of a dual clutch transmission positioned downstream of the engine and compensating for driveline disturbance resulting from the cranking via controlling an electric machine positioned downstream of the dual clutch transmission. In this way, engine starting may be conducted under a variety of vehicle operating conditions.

A power transmission system of a hybrid electric vehicle uses an engine and a motor/generator as power sources, and includes: a torque converter including a planetary gear set having first, second, and third rotating elements, the first rotating element being selectively connected to a transmission housing, the second rotating element being connected to an engine output shaft of the engine, and the third rotating element being connected to a motor output shaft of the motor/generator; an input device including a first input shaft selectively connected to the motor output shaft through one clutch and a second input shaft that is disposed on a same shaft line as the first input shaft to be selectively connected to the motor output shaft through another clutch; and a shift output device shifting and outputting rotation power of the input device.

A clutch device, comprising a first input side coupled to a first drive motor, a second input side coupled to a second drive motor, a first and second output side, wherein the first and second output sides can and the first and second input sides can be rotated about a common axis. The clutch device further includes a first clutch located between the first input side and the first output side, a second clutch located between the first input side and the second output side, and a third clutch located between the first input side and the second input side, wherein the third clutch is arranged offset relative to the first clutch.

Systems and methods are shown for meeting wheel torque demand in a hybrid vehicle with an engine, a dual clutch transmission coupled to a driveline of the vehicle downstream of the engine, and an electric machine coupled to the driveline downstream of the dual clutch transmission. In one example, a method comprises transferring transmission input torque through a clutch of the dual clutch transmission controlled to a first capacity, and in response to a desired transmission input torque exceeding the capacity, increasing torque output of the electric machine coupled downstream of the dual clutch transmission to assist in meeting a wheel torque demand. In this way, a driver-requested increase in acceleration may be met under conditions where transmission input torque is limited by clutch capacity.

A double clutch apparatus for a hybrid electric vehicle for transmitting torques of an engine and a motor to first and second input shafts includes two clutches formed in a volume between the rotor and the two coaxial input shafts, two slave cylinders operating the two clutches, an engine clutch shaft coaxially disposed between the two input shafts and an engine output shaft and connected to the rotor, an engine clutch disposed between the engine output shaft and the engine clutch shaft, and a third slave cylinder operating the engine clutch.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, the engine is started and coupled to the driveline via closing a clutch of a dual clutch transmission. Speed of the engine and clutch pressure are controlled to reduce driveline torque disturbances and provide a desired wheel torque.