Drivetrain for a hybrid propulsion system

1. A drivetrain for a powertrain system, wherein the drivetrain is arranged to transfer mechanical power/torque between an internal combustion engine, an electric machine and a driveline of a vehicle, the drivetrain including:

a gearbox including an input member disposed on a first end and an output member disposed on a second end; and

an auxiliary geartrain including a first mechanical drive mechanism, a second mechanical drive mechanism, and an auxiliary driveshaft;

wherein the auxiliary driveshaft rotatably couples the first mechanical drive mechanism and the second mechanical drive mechanism;

wherein the electric machine includes a rotor disposed within a stator;

wherein the stator is disposed on and attached to the second end of the gearbox;

wherein the rotor is disposed annular to the output member of the gearbox and rotates independently of the output member;

wherein the first mechanical drive mechanism is rotatably coupled to the input member of the gearbox;

wherein the second mechanical drive mechanism is rotatably coupled to the rotor of the electric machine; and

wherein the internal combustion engine is coupled to the input member of the gearbox via an interposing clutch and a torque converter.

2. The drivetrain of claim 1 , wherein the torque converter includes an input member coupled to a crankshaft of the internal combustion engine, and an output member of the torque converter coupled to the input member of the gearbox; and

wherein the internal combustion engine is controllably coupled to the input member of the torque converter via the interposing clutch.

3. The drivetrain of claim 1 , wherein the torque converter includes an input member coupled to a crankshaft of the internal combustion engine, and an output member of the torque converter coupled to the input member of the gearbox; and

wherein the output member of the torque converter is controllably coupled to the input member of the gearbox via the interposing clutch upstream of the first mechanical drive mechanism.

4. The drivetrain of claim 1 , further comprising an engine disconnect clutch being interposed between the internal combustion engine and the gearbox.

5. The drivetrain of claim 4 , wherein the engine disconnect clutch is interposed between the internal combustion engine and the first mechanical drive mechanism.

6. The drivetrain of claim 1 , wherein the first mechanical drive mechanism comprises a first pulley/sprocket rotatably coupled to a second sprocket via a coupling mechanism.

7. The drivetrain of claim 1 , wherein the second mechanical drive mechanism comprises a first sprocket gear coupled to a second sprocket via one of a continuous chain, meshing gearset, or a belt-and-pulley mechanism.

8. The drivetrain of claim 1 , further comprising a transfer case coupled to the output member of the gearbox, wherein the transfer case is attached to the stator of the electric machine.

9. The drivetrain of claim 8 , wherein the transfer case includes a gearing arrangement that is coupled to a second drive shaft to transfer mechanical power from the gearbox to one of a second differential or a power take-off arrangement.

10. The drivetrain of claim 1 , further comprising the gearbox and the driveline being configured in a transaxle arrangement, wherein the transaxle arrangement is coupled via half-shafts to vehicle drive wheels, and wherein the second mechanical drive mechanism of the auxiliary geartrain is coupled to one of the half-shafts.

11. The drivetrain of claim 10 , wherein the gearbox and the driveline are arranged in a front-wheel drive arrangement.

12. The drivetrain of claim 1 , wherein the driveline comprises a driveshaft coupled via axles and a differential to vehicle drive wheels.

13. The drivetrain of claim 12 , wherein the driveline is arranged in a rear-wheel drive arrangement.

14. An auxiliary geartrain for a drivetrain that is arranged to transfer mechanical power between an internal combustion engine, a gearbox, an electric machine and a driveline, the auxiliary geartrain including:

a first mechanical drive mechanism, a second mechanical drive mechanism, and an auxiliary driveshaft;

wherein the auxiliary driveshaft rotatably couples the first mechanical drive mechanism and the second mechanical drive mechanism;

wherein the electric machine includes a rotor disposed within a stator;

wherein the stator is disposed on and attached to a second end of the gearbox;

wherein the rotor is disposed annular to an output member of the gearbox and rotates independently of the output member;

wherein the first mechanical drive mechanism is rotatably coupled to an input member of the gearbox; and

wherein the second mechanical drive mechanism is rotatably coupled to the rotor of the electric machine; and

wherein the internal combustion engine is coupled to the input member of the gearbox via an interposing clutch and a torque converter.

15. The auxiliary geartrain of claim 14 , wherein the first mechanical drive mechanism comprises a first pulley/sprocket rotatably coupled to a second sprocket via a coupling mechanism.

16. The auxiliary geartrain of claim 14 , wherein the second mechanical drive mechanism comprises a first sprocket gear coupled to a second sprocket via a continuous chain.

17. The auxiliary geartrain of claim 14 , further comprising the gearbox and the driveline being configured in a transaxle arrangement, wherein the transaxle arrangement is coupled via half-shafts to vehicle drive wheels in a front-wheel drive arrangement, and wherein the rotor is disposed annular to one of the half-shafts and rotates independently of the one of the half-shafts.

18. The auxiliary geartrain of claim 14 , further comprising the gearbox and the driveline being configured in a transaxle arrangement, wherein the transaxle arrangement is coupled via half-shafts to vehicle drive wheels in an all-wheel drive arrangement, and wherein the rotor is disposed annular to one of the half-shafts and rotates independently of the one of the half-shafts.

19. The auxiliary geartrain of claim 14 , wherein the driveline comprises a driveshaft coupled via axles and a differential to vehicle drive wheels.