Methods and systems are provided for an electric drive train of a hybrid electric vehicle (HEV). In one example, the electric drive train may include a four-node planetary gear set with a first motor coupled to a first input node, a second motor coupled to a second input node and an engine coupled to a third input node of the planetary gear set. The third node is positioned between the first and second input nodes. Torque delivered to each input node is summed at an output node of the four-node planetary gear set.

A control device for an automatic transmission includes: a failure diagnosis section for diagnosing whether or not a failure has occurred in a shift control system of the automatic transmission; a fail-safe control section for fixing the automatic transmission into a predetermined gear position in response to confirmation of the failure of the shift control system of the automatic transmission; and an oil temperature rise regulation torque reduction control section for outputting a torque reduction request to suppress torque of a vehicle driving source, based on temperature of transmission operating oil of the automatic transmission, and outputting the torque reduction request in response to satisfaction of an oil temperature condition that is set lower in oil temperature when the automatic transmission is fixed in a first gear position by the fail-safe control section than when the automatic transmission is not fixed in the first gear position.

One axle of a hybrid vehicle is powered by an electric motor while a second axle of the vehicle is powered by a powertrain that includes an internal combustion engine. The electrically driven axle can be controlled in a speed control mode or in a torque control mode based on a driver demanded torque. The speed control mode is used when slip is detected at the electrically driven axle. The torque control mode is used when the electrically driven axle has traction. During a transition between these modes, the rate of change of torque is controlled to a predetermined level to mitigate noise, vibration, and harshness.

A vehicle control unit performs filling control in which the vehicle control unit boosts an oil pressure in a second oil passage by supplying electric power to a pressure regulating valve with a switch valve being in a first state in which the switch valve connects a first oil passage to a clutch and disconnects the second oil passage from the clutch, torque replacement control in which the vehicle control unit increases motor torque while reducing shaft torque of an engine, and clutch disengagement control in which the vehicle control unit disengages the clutch while performing hydraulic control by the pressure regulating valve with the switch valve being in the second state in which the switch valve connects the second oil passage to the clutch and disconnects the first oil passage from the clutch.

Systems and methods for operating a vehicle that includes an engine and an integrated starter/generator are described. In one example, torque generated via the engine is based on a requested driveline torque and a torque of an electric machine when degradation of an engine sensor is present. The torque generated via the engine may be adjusted responsive to a requested engine torque and a feedback engine torque that is based on output of an engine airflow sensor.

A method for controlling an engine clutch of an electrified vehicle is provided to easily engage and disengage an engine clutch by applying a launch engagement control method that utilizes power from both of an engine and a motor in accordance with the variation of the number of revolutions per hour of the engine and the usage rate of electrical energy by a motor to engage the engine clutch in a terrain mode and by applying a control method that disengages an engine clutch early in accordance with the number of revolutions per hour of the engine and the shaft torque of the engine clutch in the terrain mode.

A vehicle control system is provided to improve a response and an acceleration feel of a vehicle having a continuously variable transmission. The vehicle control system is configured to control an output power of a prime mover and a speed ratio of a transmission in such a manner that an actual driving force is increased stepwise to the required driving force to be achieved by a kick-downshifting so as to temporarily hold an increase in an acceleration during execution of the kick-downshifting.

The invention relates to a method for synchronising the common speed (ω p) of two concentric primary shafts (1, 6) of a hybrid transmission in a hybrid operating mode wherein said two shafts are rotatably connected by a first coupling means (5), with the speed (ω s) of a secondary transmission shaft (10) comprising at least one idler pinion for allowing the coupling of one of said pinions (11, 12) to the shaft (10) thereof by closing a second coupling means (13) that does not have mechanical synchronisation bodies, the torque (Te) of the electric machine being temporarily reduced during the synchronisation phase in order to meet the conditions of a perfect coupling when the value thereof caps at an upper limit value (T.sub.e.sup.max) or a lower limit value (T.sub.e.sup.min).

A system and method for controlling a hybrid electric vehicle using a driving tendency are provided. The method includes determining a driving tendency level based on data to determine a driving tendency of a driver and determining a target engine torque using an engine torque map based on a vehicle speed and a required torque. Whether the driving tendency level corresponds to a predetermined level is determined as well as whether the required torque is equal to or greater than a torque that corresponds to an optimal operating point of an engine when the driving tendency level corresponds to the predetermined level. The target engine torque is then adjusted when the required torque is equal to or greater than the torque that corresponds to the optimal operating point of the engine.

A method for operating a driveline of a vehicle includes adjusting operation of an electric machine to provide a torque difference between a driver demand torque and an engine output torque, when the electric machine is not operating in an operating range in which electric machine efficiency is less than a threshold efficiency. The operating range has a first, positive torque limit defining a positive extent of the operating range and a second, negative torque limit defining a negative extent of the operating range. In response to the torque difference being within the operating range and greater than zero, the torque output of the electric machine is maintained at the first torque limit, whereas in response to the torque difference being within the operating range and less than zero, the torque output of the electric machine is maintained at the second torque limit.