An electronic control unit is configured to select one of a series mode, a series-parallel mode and a parallel mode as a running mode. A load level of a hybrid vehicle is set to a value that is high in the order of a load level at which the parallel mode is selected, a load level at which the series-parallel mode is selected, and a load level at which the series mode is selected. That is, the electronic control unit selects the series-parallel mode in an intermediate load region, selects the series mode in a low load region, and selects the parallel mode in a high load region.

A drive device and method for a motor vehicle, provided with a combustion engine machine, with a first electric machine and with a second electric machine, wherein a drive shaft of the combustion engine machine can be coupled by a first clutch to a drive shaft of the first electric machine, which is connected via a transmission drive to a drive shaft of the drive device. At the same time, the gear device is permanently coupled to the drive shaft of the first electric machine and provided with a planetary gear that can be coupled by a second clutch to the drive shaft of an internal combustion engine, wherein the second electric machine is permanently coupled to the drive shaft.

A control process including the following steps is executed. The control process includes, at the time of switching from series-parallel mode to series mode, a step of reducing an engine torque, a step of releasing a clutch, a step of reducing a reaction torque of a first rotary electric machine and a step of increasing a torque of a second rotary electric machine, and, when synchronization is started and a step of increasing a positive torque of the first MG, a step of starting engagement of a clutch, and, when a rotation speed of the first rotary electric machine and a rotation speed of an engine are synchronous with each other, a step of engaging the clutch.

A control process including the following steps is executed. The control process includes, at the time of switching from series-parallel mode to series mode, a step of reducing an engine torque, a step of releasing a clutch, a step of reducing a reaction torque of a first rotary electric machine and a step of increasing a torque of a second rotary electric machine, and, when synchronization is started and a step of increasing a positive torque of the first MG, a step of starting engagement of a clutch, and, when a rotation speed of the first rotary electric machine and a rotation speed of an engine are synchronous with each other, a step of engaging the clutch.

An electronic control unit stores a vehicle load at the time when the vehicle is switched into an ignition off state, stops operation of an electric oil pump when the vehicle load is small, and operates the electric oil pump when the vehicle load is large. Thus, a decrease in service life due to an increase in the number of times of the start of the electric oil pump is suppressed, and, when it is estimated that the vehicle load is large, the response of the start of a vehicle, which makes a driver experience a feeling of strangeness, is improved by starting the electric oil pump together with switching the vehicle into an ignition on state.

An electronic control unit stores a vehicle load at the time when the vehicle is switched into an ignition off state, stops operation of an electric oil pump when the vehicle load is small, and operates the electric oil pump when the vehicle load is large. Thus, a decrease in service life due to an increase in the number of times of the start of the electric oil pump is suppressed, and, when it is estimated that the vehicle load is large, the response of the start of a vehicle, which makes a driver experience a feeling of strangeness, is improved by starting the electric oil pump together with switching the vehicle into an ignition on state.

A vehicle control system includes a first electric motor that causes a vehicle to travel, a second electric motor that generates power by using an output of a power source and starts the power source, a power storage device that stores the power generated by the second electric motor and supplies the power to the first electric motor, a monitoring device that monitors a failure state of the vehicle, and a switch that switches the vehicle to travel from the first electric motor to the second electric motor. In a case of a predetermined driving state in which the monitoring device detects a failure of the first electric motor and a driving force is obtained from the second electric motor, the monitoring device controls the switch to switch the driving force for causing the vehicle to travel from the first electric motor to the second electric motor.

A control apparatus for a hybrid electric vehicle that includes (i) an engine, (ii) a first electric motor, (iii) a second electric motor, (iv) first wheels, (v) second wheels and (vi) an engagement device disposed between the engine/first electric motor and the first wheels. The engagement device establishes and cuts off transmission of a power of the engine/first electric motor to the first wheels, by connecting and disconnecting between an input rotary member and an output rotary member. During running of the vehicle in a running mode in which the engagement device is released and the vehicle is caused to run by a power of the second electric motor, it is determined whether the engagement device is being released or not, based on (a) a rotational speed difference between the input and output rotary members and (b) a rotational state of the engine or the first electric motor.

A control apparatus for a hybrid electric vehicle that includes (i) an engine, (ii) a first electric motor, (iii) a second electric motor, (iv) first wheels, (v) second wheels and (vi) an engagement device disposed between the engine/first electric motor and the first wheels. The engagement device establishes and cuts off transmission of a power of the engine/first electric motor to the first wheels, by connecting and disconnecting between an input rotary member and an output rotary member. During running of the vehicle in a running mode in which the engagement device is released and the vehicle is caused to run by a power of the second electric motor, it is determined whether the engagement device is being released or not, based on (a) a rotational speed difference between the input and output rotary members and (b) a rotational state of the engine or the first electric motor.

An embodiment power train for a vehicle includes a first input shaft configured to receive rotating forces from a first motor and an engine, a second input shaft configured to receive a rotating force from a second motor, an output shaft disposed in parallel with the first input shaft and the second input shaft, a transmission gear set in which a plurality of gear sets having different gear ratios are engaged with and coupled to the first input shaft and the output shaft, a shifting unit configured to select a gear set of the plurality of gear sets based on a traveling speed of the vehicle, and a motor-side transfer gear set engaged with and coupled to the second input shaft and the output shaft.