Methods and system are described for changing a driveline gear range from a higher gear range to a lower gear range. The driveline may include two electric machines and four clutches in a four wheel drive configuration. The methods and systems permit a driveline to change from a higher gear range to a lower gear range without stopping a vehicle.

A drive device (7) for a motor vehicle drive train of an electric vehicle has a plurality of electric machines (12, 13, 14) and a transmission, where different transmission ratios between an input shaft and an output side can be selected. In this case, a first electric machine (13) is connected to the input shaft of the transmission or can be connected thereto, and the output side of the transmission is coupled to at least one output drive (9, 10), which is used in the motor vehicle drive train to connect a respective drive axle of the electric vehicle. In order to achieve the highest possible driving comfort by means of this drive device (7), a second electric machine (14) is also permanently connected to the output side.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

A transmission includes an input shaft and an output shaft, the input shaft selectively accepting a torque input from a prime mover, and the output shaft selectively providing torque output to a driveline. A controller determines a shaft displacement angle representing an angle value of rotational displacement difference between at least two shafts of the transmission, and performs a transmission operation responsive to the shaft displacement angle.

A power transmission control device acquires rotation speed information of an idle gear corresponding to a target engagement member and rotation speed information of a sleeve corresponding to an engagement member, sets one rotation speed changeable by a power source as a synchronization side rotation speed, sets the other rotation speed as a target synchronization side rotation speed, allows a differential rotation between the synchronization side rotation speed and the target synchronization side rotation speed to match a predetermined differential rotation by changing the synchronization side rotation speed using the power source after a power transmission releasing state is selected due to a gear changing request, performs an engagement operation, inverts a sign of the predetermined differential rotation, and switches to the power transmission state while allowing the differential rotation to match the predetermined differential rotation of which the sign is inverted.

A method for performing rotational speed synchronisation of a first transmission component having a first initial rotational speed with a second transmission component having a second initial rotational speed, so that they rotate with the same final rotational speed during a gear switch from an initial driving gear to a final driving gear in a stepped gear transmission for a hybrid electric or electric drive train having an electric traction motor. The method including calculating a total frictional work resulting from performing the total rotational speed synchronisation by means of a mechanical synchroniser of the stepped gear transmission only, and if the calculated total frictional work exceeds a maximal frictional work of the mechanical synchroniser, performing the rotational speed synchronisation by means of both the electric traction motor and the mechanical synchroniser.

A drive train, including: a first electric motor; a second electric motor; and a transmission system including a first input shaft driveably connected to the first electric motor, a second input shaft driveably connected to the second electric motor, a first gear train including a first gear element rotatably mounted on the first input shaft and a second gear element rotatably mounted on the second input shaft, a second gear train including a third gear element rotatably mounted on the first input shaft and a fourth gear element rotatably mounted on the second input shaft, a gear selector assembly arranged to selectively lock either the first and third gear elements for rotation with the first input shaft or the second and fourth gear elements for rotation with the second input shaft.

An automated mechanical transmission for a vehicle includes a main gearbox assembly comprising a main shaft and being adapted to be shiftable between at least one engaged state and a neutral state; a split gearbox assembly comprising an input shaft and being adapted to be shiftable between a first engaged state, a second engaged state and a neutral state; a countershaft; a crawler gearbox assembly comprising a crawler gear engagement member which is adapted to selectively engage and disengage a crawler gear defining a torque path from the input shaft to the main gearbox assembly via the countershaft; a gearbox brake; and transmission control unit. The transmission is configured to be settable in an AMT neutral state defined by the main gearbox assembly being in the neutral state. When the transmission control unit obtains a request to engage the crawler gear from the AMT neutral state, the transmission control unit is configured to apply the gearbox brake so that a rotational speed of the countershaft is reduced to a first predetermined rotational speed which is higher than a zero rotational speed; and when the first predetermined rotational speed is reached, release the gearbox brake, set the split gearbox assembly to the neutral state and engage the crawler gear by the crawler gear engagement member.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

A shift control method for an automated manual transmission (AMT) of a vehicle includes: when a shift operation is started, a torque of the second motor is increased so that a change in an output torque of the output shaft due to a change in a torque of the first motor is minimized while the torque of the first motor is being decreased. According to the shift control method, the increased torque of the second motor is maintained to be constant while controlling transmission release, speed synchronization, and transmission coupling. After the control over the transmission coupling is completed, the torque of the second motor is controlled so that the output torque of the output shaft follows a predetermined target torque while the torque of the first motor is controlled to be increased.