A powertrain has an internal combustion engine provided with an accessory transmission that includes a first pulley connected to a crankshaft of the engine, a second pulley connected to a shaft of an electric machine, and a belt connecting the first and the second pulleys to each other to rotate in the same direction of rotation (R). The electric machine is operated to supply an active torque to the second pulley during start-up of the internal combustion engine by means of a starter motor.

Methods and systems are provided for engaging and disengaging an electromagnetic clutch of a two-speed accessory drive of an engine of a vehicle. In one example, a method comprises, responsive to an electrical demand being higher than a threshold electrical demand, operating an electric machine of the vehicle in a motor mode to reduce a speed of a grounding gear of a planetary gear set of a two-speed accessory drive (TSAD) of the vehicle; and engaging an electromagnetic clutch responsive to the speed of the grounding gear reaching a clutch engagement threshold speed.

An engine accessory drive (EAD) system for an engine includes a motor-generator (MGU) unit operably coupled to an accessory. The EAD system also includes a gearbox assembly, which includes a first gear train operably coupled to the MGU, and a second gear train operably coupled to an output of the engine. The gearbox assembly also includes a clutch selectively coupling the first gear train with a second gear train. The EAD system further includes a starter assembly, which includes a starter shaft operably coupled to the second gear train. The starter assembly also includes a starter pinion coupled to the starter shaft, and an actuator configured to selectively engage the starter pinion with a flywheel of the engine. Further yet, the EAD system includes an EAD controller configured to selectively operate the EAD system in one of a generator mode, an accessory drive mode, and a starter mode.

An engine accessory drive (EAD) system for an engine includes a motor-generator (MGU) unit operably coupled to an accessory. The EAD system also includes a gearbox assembly, which includes a first gear train operably coupled to the MGU, and a second gear train operably coupled to an output of the engine. The gearbox assembly also includes a clutch selectively coupling the first gear train with a second gear train. The EAD system further includes a starter assembly, which includes a starter shaft operably coupled to the second gear train. The starter assembly also includes a starter pinion coupled to the starter shaft, and an actuator configured to selectively engage the starter pinion with a flywheel of the engine. Further yet, the EAD system includes an EAD controller configured to selectively operate the EAD system in one of a generator mode, an accessory drive mode, and a starter mode.

A vehicle includes an engine, electric machine, starter-generator, and a controller. The engine and electric machine are each configured to propel the vehicle. The starter-generator is coupled to the engine and is configured to adjust engine speed during an engine start-up event. The controller is programmed to, in response to engine speed increasing towards a target speed during an engine start-up event, generate a target drag torque with the starter-generator to reduce overshoot of the target engine speed.

A vehicle includes an engine and an electric machine coupled to a transmission element. The electric machine is also selectively coupled with the engine by a clutch. The vehicle includes a belt integrated starter-generator (BISG) operatively coupled to the engine. An electronic controller includes one or more inputs adapted to receive a temperature measurement and a request to start the engine. The electronic controller is programmed to, in response to the one or more inputs receiving the request to start the engine and the temperature measurement less than a threshold temperature measurement, effect actuation of the electric machine and close the clutch to apply a first torque to the engine. The electronic controller is further programmed to, in response to an engine speed achieving an engine speed threshold, effect actuation of the BISG to apply a second torque to the engine.

A powertrain system including an electric machine rotatably coupled to a crankshaft of an internal combustion engine via a belt is described, wherein the electric machine is disposed to generate torque. A method for controlling the electric machine includes monitoring rotational position of the electric machine, and periodically executing a speed observer to determine a rotational speed of the electric machine based upon the monitored rotational position of the electric machine. An acceleration observer is periodically executed to determine an acceleration rate, wherein the acceleration rate is determined based upon a time-based change in the rotational speed of the electric machine. A virtual inertia term is determined based upon the acceleration rate, and a torque compensation term is determined based upon the virtual inertia term and the acceleration rate. The electric machine is controlled to generate torque based upon the torque compensation term.

A method and an apparatus for controlling a mild hybrid electric vehicle are provided. The method includes detecting data for operating the vehicle and determining a target torque of an engine based on the detected data. Additionally, the method includes determining whether an operating condition of a limiting logic of a combustion torque of the engine is satisfied based on a temperature of coolant of the engine and operating the limiting logic when the operating condition of the limiting logic is satisfied. A first available combustion torque of the engine is determined based on a speed of the engine and the temperature of the coolant when the limiting logic is operated and a target torque of a MHSG is determined based on the target torque of the engine and the first available combustion torque of the engine. The MHSG is then operated to generate the target torque of the MHSG.

A vehicle includes an engine having a crankshaft, an electric machine having a shaft, and a front end accessory drive (FEAD). The FEAD includes a multi-speed pulley assembly mounted to one of the crankshaft and the shaft, a pulley mounted to the other of the crankshaft and the shaft, and a tension member trained around the multi-speed pulley assembly and the pulley. The multi-speed pulley assembly is configured to establish a low speed ratio between the shaft and the crankshaft and a high speed ratio between the shaft and the crankshaft. A vehicle controller is programmed to, in switch between the high speed ratio and the low speed ratio to optimize operating conditions of the FEAD.

A stop/start hybrid vehicle includes an engine configured for stopping and restarting during travel, a multiple-ratio transmission, a brake pedal, and an electronic parking brake. The transmission can be shifted into reverse gear either when the brake pedal is applied or unapplied. At least one controller is programmed to control the vehicle under these scenarios. If the engine is off and the brake pedal is applied when the transmission is shifted into reverse, the controller restarts the engine. If the engine is off and the brake pedal is unapplied when the transmission is shifted into reverse, the controller inhibits the engine from restarting until the brake pedal is applied. The controller can also be programmed to apply the electronic parking brake while the brake pedal remains unapplied after a predetermined time from the transmission being shifted into the reverse gear.