One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.

One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.

A wet friction disc includes a friction surface and a lubrication groove through which a lubricant supplied to the friction surface flows. The lubrication groove has a plurality of circumferential groove portions that extends in a circumferential direction and a plurality of intersecting groove portions that extends in directions intersecting the circumferential direction. At least one of the circumferential groove portions has a through-hole that extends through the wet friction disc between an opposite surface facing s mating member and a surface on the opposite side in an axial direction.

A wet friction disc includes a friction surface and a lubrication groove through which a lubricant supplied to the friction surface flows. The lubrication groove has a plurality of circumferential groove portions that extends in a circumferential direction and a plurality of intersecting groove portions that extends in directions intersecting the circumferential direction. At least one of the circumferential groove portions has a through-hole that extends through the wet friction disc between an opposite surface facing s mating member and a surface on the opposite side in an axial direction.

A rotational coupling device drives an output synchronous with either of two inputs. The device includes a hub disposed about an axis and an output member supported on the hub for rotation about the axis. First and second input members disposed about the hub are configured to rotate in first and second rotational directions and at first and second speeds, respectively, with at least one of the directions and speeds differing. A clutch member is disposed axially between the input members and coupled to the output member. An electromagnet is on an opposite side of the second input member relative to the clutch member. When the electromagnet is deenergized, the clutch member engages the first input member and the output member rotates with the first input member. When the electromagnet is energized, the clutch member engages the second input member and the output member rotates with the second input member.

A rotational coupling device drives an output synchronous with either of two inputs. The device includes a hub disposed about an axis and an output member supported on the hub for rotation about the axis. First and second input members disposed about the hub are configured to rotate in first and second rotational directions and at first and second speeds, respectively, with at least one of the directions and speeds differing. A clutch member is disposed axially between the input members and coupled to the output member. An electromagnet is on an opposite side of the second input member relative to the clutch member. When the electromagnet is deenergized, the clutch member engages the first input member and the output member rotates with the first input member. When the electromagnet is energized, the clutch member engages the second input member and the output member rotates with the second input member.

An inner peripheral surface of an outer cylindrical tubular portion and an outer peripheral surface of an inner cylindrical tubular portion of a rotor are respectively shaped into a stepped form. A radial distance between the outer cylindrical tubular portion and the inner cylindrical tubular portion at a counter-armature side location is larger than that of an armature side location in the rotor. An outer peripheral surface of an outer cylindrical tubular portion and an inner peripheral surface of an inner cylindrical tubular portion of a stator are respectively shaped into a stepped form. A radial distance between the outer peripheral surface of the outer cylindrical tubular portion and the inner peripheral surface of the inner cylindrical tubular portion at the counter-armature side location is larger than that of the armature side location in the stator.

A dynamic controllable dog clutch (DCDC) includes a pocket plate, a notch plate, and a linear actuator having a stator and a translator. The translator is axially movable between (i) an engaged position in which a locking member axially extends through the a pocket of the pocket plate and engages a notch of the notch plate to thereby mechanically couple the pocket plate and the notch plate together to prevent relative rotation of the pocket plate and the notch plate with respect to each other about a common rotational axis and (ii) a disengaged position in which the locking member is disengaged from the notch of the notch plate to thereby mechanically decouple the pocket plate and the notch plate together to enable relative rotation of the pocket plate and the notch plate with respect to each other about the common rotational axis.

One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.

One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.