An acceleration method for a hybrid drivetrain includes providing the hybrid drivetrain, setting an initial torque transmission ratio of a belt-drive transmission to a lower transmission ratio, and opening a first disconnect clutch to interrupt torque transmission between an internal combustion engine and an electric machine. The method also includes receiving an acceleration command, shifting the torque transmission ratio with a transmission adjustment gradient from the lower transmission ratio towards an upper transmission ratio, increasing a rotor speed of a rotor shaft of the electric machine with a rotor shaft adjustment gradient, and engaging a first disconnect clutch to rotate an ICE shaft to start the internal combustion engine and increase a rotational speed of the ICE shaft towards a current rotor speed.

A control device for a hybrid vehicle that includes an internal combustion engine, a motor, and a clutch provided between the internal combustion engine and the motor includes a first start control unit that starts the internal combustion engine without causing the motor to perform cranking, and a second start control unit that starts the internal combustion engine by causing the motor to perform cranking. After the first start control unit performs start control of the internal combustion engine, the second start control unit starts the internal combustion engine when a crank shall of the internal combustion engine stops for a predetermined time or longer or the crank shaft rotates in an opposite direction to the direction of the cranking.

Systems and methods for starting an internal combustion engine of a hybrid vehicle are presented. In one example, the internal combustion is started via closing a driveline disconnect clutch and limiting a torque output rate of an electric machine so that vehicle speed may increase continuously without decreasing during engine cranking and run-up periods.

A controller executes a first restarting process when restarting of an engine is requested under a condition where an engine speed is less than a determination speed. In the first restarting process, cranking of the engine is performed by a motor generator in a state in which the motor generator is connected to a crankshaft through engagement of a clutch, and fuel injection and ignition are initiated in the engine when a combustion initiation condition is satisfied in this state. The controller executes a second restarting process when restarting of the engine is requested under a condition where the engine speed is greater than or equal to the determination speed. In the second restarting process, fuel injection and ignition are initiated in the engine, and the motor generator is connected to the crankshaft through engagement of the clutch after the engine has been restarted.

A control device for a hybrid electric vehicle includes an electronic control unit. The electronic control unit is configured to perform a start-up control of shifting the connection and disconnection clutch to a coupled state at the time of starting the internal combustion engine to rotate the internal combustion engine by the driving torque of the electric motor, and starting the first fuel injection mode using the direct injection injector. The electronic control unit is configured to switch from the first fuel injection mode to a second fuel injection mode for using the port injector prior to an end of the start-up control when the number of times of combustion cycles of the internal combustion engine with the first fuel injection mode reaches a predetermined first target number of times.

A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes supply electrical current to a starter motor independently from supplying electrical current to a starter solenoid. In addition, the method includes adjusting and amount of electrical current that is delivered to the starter motor in response to a level of urgency of an automatic engine start.

Systems and methods for selecting and scheduling which of a plurality of engine starting devices starts an internal combustion engine of a hybrid vehicle are presented. In one example, a scheduled start of the internal combustion engine via a driveline disconnect clutch is withdrawn during conditions when both a transmission gear shift is requested or in process and when a driver urgency level is greater than a threshold level.

A torque limiter that enables setting a larger torque capacity although being compact and easy to incorporate into a power transmission mechanism, is provided. A torque limiter is incorporated into a power transmission mechanism for transmitting power from a starter motor to a crankshaft of an internal combustion engine. The torque limiter includes a driven gear for receiving power from the starter motor and a transmission gear for transmitting power. The driven gear and the transmission gear are coaxially disposed in a relatively rotatable manner. The driven gear and the transmission gear are configured to transmit power therebetween via a friction member. The friction member has a circular disc shape with an outer diameter that is larger than an outer diameter of the driven gear.

Systems and methods for operating a hybrid vehicle are described. In one example, a torque reserve for starting an engine via an electric machine is adjusted responsive to vehicle operating conditions. The torque reserve may set aside a portion of torque that an electric machine may produce for cranking and starting an engine.

Systems and methods for selecting which of a plurality of engine starting devices starts an internal combustion engine of a hybrid vehicle are presented. In one example, engine starting devices may be selected and operated while a vehicle is operating in a creep mode. The system and method may place a driveline disconnect clutch in a wait state or engage a flywheel starter to improve engine starting.