A drive force control system appropriately controls motors each connected to a corresponding one of drive wheels, so that a vehicle can be propelled with high efficiency. First motor and second motors are controlled in such a manner that a sum of torques transmitted to a right front wheel and a left rear wheel equals to a total value of required torques of the right front wheel and the left rear wheel. A target torque of the first motor and a target torque of the second motor achieving a smallest amount of power output from an electrical power source, for the output torques from the first motor and the second motor are calculated. A torque is generated by the first motor based on the target torque of the first motor calculated, and a torque is generated by the second motor based on the target torque of the second motor calculated.

Methods and systems are provided for operating a powertrain or driveline of a hybrid vehicle that includes two electric machines and a transmission are described. In one example, vehicle propulsion is maintained while transmission operating parameters are determined for improving transmission operation. In particular, a rear drive unit maintains vehicle speed and monitors torque delivered via an output of the transmission.

Methods and systems are provided for operating a vehicle that may be propelled via a primary axle and a secondary axle. In one example, a propulsion source of a secondary axle may be decoupled from at least one wheel via a dog clutch that includes teeth. The dog clutch may be disengaged in a way that reduces driveline noise and may reduce a possibility of driveline degradation.

A method includes estimating a first pressure at a first location of a clutch based on a flow rate of a fluid in the clutch, computing a first torque lead value based on the first pressure, computing a second torque lead value based on a second pressure, computing a third torque lead value by combining the first torque lead value and the second torque lead value, and applying torque from a motor of the vehicle based on the third torque lead value.

Methods and systems for operating a clutch of an axle are provided. In one example, the clutch may be characterized in static or dynamic conditions. The clutch characterization may be a basis for subsequently operating the clutch during gearbox shifting. In particular, an amount of torque that is transferred via the clutch may be controlled or adjusted according to the clutch characterization.

A clutch arrangement for a hybrid vehicle powertrain, comprises: an input shaft (30) to be connected to a crankshaft (26) of an internal combustion engine (12); an output shaft (32) for connection to a transmission (20); a one-way clutch (50) for comprising an inner race (52) connected to rotate with the input shaft (30) and an outer race (54); a coupling hub (58) rotationally coupled with the output shaft (32); and a synchronizer ring (60) arranged between the coupling hub (58) and the one-way clutch (50), the synchronizer ring cooperating with the outer race of the one-way clutch. A coupling sleeve unit (62) is selectively and axially moveable across the coupling hub (58), synchronizer ring (60) and outer race (54) between three positions: a neutral position, a first position where the coupling sleeve unit couples in rotation said coupling hub, the synchronizer ring and the outer race; and a second position where the coupling sleeve unit couples in rotation the coupling hub, the synchronizer ring, the outer race and the inner race. Also presented is a powertrain comprising such clutch arrangement.

Methods and systems for operating a clutch of an axle are provided. In one example, the clutch may be characterized in static or dynamic conditions. The clutch characterization may be a basis for subsequently operating the clutch during gearbox shifting. In particular, an amount of torque that is transferred via the clutch may be controlled or adjusted according to the clutch characterization.

A method for learning engine clutch kiss point of a hybrid vehicle is provided. The method includes adjusting a speed of a driving motor to be reduced when a deceleration event is generated in front of the hybrid vehicle and adjusting a speed of an engine to be synchronized with the speed of the driving motor. An engine clutch that connects the engine with the driving motor or disconnects the engine from the driving motor is engaged to start and then a kiss point of the engine clutch is learned by detecting the kiss point that is generated when the engine clutch is in a slip state.

A method of reducing rollback of a electric vehicle, including determining a position baseline of the electric vehicle; determining a position compensated speed of the electric vehicle based on the position baseline; determining a hold torque as a function of the position compensated speed; and generating a command to apply the hold torque to the motor-generator of the electric vehicle.

A method of controlling an axle assembly. The method includes executing a speed synchronization mode and operating a clutch actuator to shift a clutch from a neutral position toward an engaged position. The method may also include executing a low torque synchronization mode when the clutch cannot be shifted from a neutral position to an engaged position within a first predetermined period of time.