Since a maximum rotation speed is set to a lower value when a supercharging pressure from a supercharger is high than when the supercharging pressure is low, an engine torque is decreased at a relatively low engine rotation speed and the engine rotation speed is less likely to fall into a high-rotation state. Since the maximum rotation speed is set to a relatively high value when the supercharging pressure is relatively low and the engine rotation speed is less likely to fall into a high-rotation state, the engine torque is not decreased at a relatively high engine rotation speed and power performance can be easily secured. Accordingly, it is possible to curb a decrease in power performance due to a decrease in the engine torque and to prevent the engine rotation speed from falling into a high-rotation state.

When a speed difference between a maximum rotation speed and an engine rotation speed, that is, an actual rotation speed difference, is equal to or less than a margin rotation speed difference, an engine operating point is changed such that the actual rotation speed difference becomes greater than the margin rotation speed difference. Accordingly, the speed difference between the maximum rotation speed and the engine rotation speed is prevented from becoming equal to or less than the margin rotation speed difference. As a result, since a relatively sufficient margin is secured in the difference between the maximum rotation speed and the engine rotation speed, it is possible to prevent the engine rotation speed from falling into a high-rotation state in which the engine rotation speed exceeds the maximum rotation speed.

Since a maximum rotation speed of a second rotary machine is set to a lower value when a supercharging pressure is high than when the supercharging pressure is low, an engine torque decreases with an rotation speed of the second rotary machine which is relatively low and the rotation speed is less likely to fall into a high-rotation state. When the supercharging pressure is relatively low and the rotation speed is less likely to reach an upper-limit rotation speed of the second rotary machine, the maximum rotation speed is set to a relatively high value. Accordingly, the engine torque does not decrease to the rotation speed which is relatively high and power performance can be easily secured. As a result, it is possible to prevent a decrease in power performance due to the decrease in the engine torque and to prevent the rotation speed from falling into a high-rotation state.

It is determined whether chargeable and dischargeable electric power of a battery which is a power storage device are limited. When it is determined that the chargeable and dischargeable electric power of the battery is limited, an electric power balance target value of the battery during gear shifting control in a stepped gear shifting unit which is a mechanical gear shifting mechanism is calculated. A smaller value is calculated as a change rate limit value when the chargeable and dischargeable electric power is small than when the chargeable and dischargeable electric power is great, and the calculated change rate limit value is used to perform gear shifting control in the stepped gear shifting unit.

An MG1 torque at a time of decreasing an engine speed of an engine is made larger when a turbocharging pressure by a turbocharger is higher than when the turbocharging pressure is lower. In this way, even if the losses of pumps of the engine differ due to the remaining turbocharging pressure during a transition of stopping the engine in turbocharging, it is possible to appropriately reduce the engine speed. Therefore, when the engine is being brought to a stop, it is possible to appropriately suppress vibration generated in the vehicle.

When an engine during rotation stop is started, a target cranking speed is set to a value at which a first rotating machine MG1 is maintained in an electric power generation state when a request engine power is an output that needs a turbocharging pressure and which is higher than when the request output is not the output that needs the turbocharging pressure, and even after the engine is brought into the operating state, an MG1 cranking torque is controlled to apply a torque for increasing an engine speed of the engine to the target cranking speed to the engine. In this way, it is possible to increase the engine speed after an autonomous operation more quickly while suppressing power consumption of the first rotating machine MG1.

An electronic control unit of a vehicle includes (a) a target operating point setting unit that calculates a request driving force requested for a vehicle, and set a target engine operating point through a slow change process for obtaining an engine output that slowly changes with respect to a request engine output implementing the request driving force, (b) a smoothing factor setting unit that changes a smoothing factor used for the slow change process according to an amount of change in a turbocharging pressure in the engine and sets the smoothing factor to a smaller value when the amount of change in the turbocharging pressure is smaller than when the amount of change in the turbocharging pressure is larger, and (c) a drive controller that controls the engine and the continuously variable transmission such that the engine operating point is the target engine operating point.

A vehicle transmission system may include an engine outputting power from fuel combustion, a transmission coupled to the engine and including at least one clutch to control torque input from the engine, an supercharger compressing an intake air and supplying the compressed intake air to the engine, and a control unit, where, when a predetermined acceleration condition is satisfied, the control unit is configured to operate the supercharger and to control the transmission according to a transmission clutch stroke operation map corresponding to the operation of the electric supercharger, to vary an engagement speed of the clutch when the supercharger is operated.

An indicator control system includes an indicator configured to show a rotational speed of an internal combustion engine, and a controller configured to control an indicated rotational speed, which is the rotational speed to be shown by the indicator. The controller is configured such that, during a specific period in which the rotational speed of the internal combustion engine is reduced from a first rotational speed to a rotational speed lower than the first rotational speed and then increased to a second rotational speed higher than the first rotational speed, the controller increases the indicated rotational speed to the second rotational speed without reducing the indicated rotational speed from the first rotational speed to the rotational speed lower than the first rotational speed.

A vehicle transmission system may include an engine outputting power from fuel combustion, a transmission coupled to the engine and including at least one clutch to control torque input from the engine, an supercharger compressing an intake air and supplying the compressed intake air to the engine, and a control unit, where, when a predetermined acceleration condition is satisfied, the control unit is configured to operate the supercharger and to control the transmission according to a transmission clutch stroke operation map corresponding to the operation of the electric supercharger, to vary an engagement speed of the clutch when the supercharger is operated.