Systems and methods for improved gearboxes for eVTOL aircraft

1. An electric engine for an aircraft, comprising:

an electric motor assembly including a stator and a rotor;

an inverter assembly;

a gearbox assembly including:

a sun gear;

a main shaft including a length of the main shaft that extends from a first end of the main shaft through the gearbox assembly and through the electric motor assembly to a second end of the main shaft;

a bearing including an inner race mechanically coupled to the main shaft and an outer race mechanically coupled to the rotor, wherein the bearing is mechanically coupled to a shaft flange assembly configured to rotate with the shaft, wherein the shaft flange assembly is mechanically coupled to the main shaft; and

a hydrodynamic bearing located between the main shaft and the sun gear.

2. The electric engine of claim 1 , wherein the bearing comprises a deep groove ball bearing.

3. The electric engine of claim 1 , wherein the bearing comprises a rolling bearing.

4. The electric engine of claim 1 , wherein the hydrodynamic bearing includes oil.

5. The electric engine of claim 1 , further comprising a heat exchanger including one or more liquid flow paths fluidically coupled to the gearbox assembly and electric motor assembly.

6. The electric engine of claim 5 , wherein the liquid flow paths are configured to allow flow of oil.

7. The electric engine of claim 5 , wherein the hydrodynamic bearing comprises liquid from the one or more liquid flow paths.

8. The electric engine of claim 1 , wherein the main shaft traverses through the sun gear, wherein the sun gear is hollow.

9. The electric engine of claim 8 , wherein the hydrodynamic bearing is disposed between an outer surface of the main shaft and an inner surface of the sun gear.

10. The electric engine of claim 1 , wherein the bearing is configured to support the rotor.

11. The electric engine of claim 1 , wherein the hydrodynamic bearing is configured to counteract a rotor moment load experienced by the sun gear.

12. The electric engine of claim 1 , wherein the gearbox assembly further comprises a planetary gear.

13. The electric engine of claim 1 , wherein the gearbox assembly further comprises a ring gear.

14. The electric engine of claim 1 , wherein the gearbox assembly further comprises a planetary carrier.

15. An electric engine for an aircraft, comprising:

an electric motor assembly including a stator and a rotor;

an inverter assembly;

a gearbox assembly including:

a sun gear, wherein the sun gear is hollow; and disposed concentric with the rotor; and

a bearing including an outer race mechanically coupled to an inner surface of the rotor, wherein the outer race of the bearing is mechanically coupled to an inner surface of the sun gear, wherein a first end of the sun gear and a first end of the rotor meet on the outer race of the bearing.

16. The electric engine of claim 15 , wherein the bearing is configured to guide a rotation of the sun gear and the rotor.

17. The electric engine of claim 15 , further comprising a shoulder of the first end of the sun gear disposed concentric with a shoulder of the first end of the rotor, wherein the shoulders cooperate to restrict movement of the bearing in an axial direction of a shaft.

18. The electric engine of claim 15 , wherein a diameter of the outer race of the bearing is substantially the same as a diameter of the inner surface of the first end of the sun gear and a diameter of the inner surface of the first end of the rotor.

19. The electric engine of claim 15 , wherein the outer race of the bearing is configured to align the first end of the sun gear with the first end of the rotor such that the first end of the sun gear abuts the first end of the rotor.

20. The electric engine of claim 15 , wherein the bearing comprises a rolling bearing.

21. The electric engine of claim 15 , wherein the sun gear and rotor are removably attached to each other.

22. The electric engine of claim 15 , wherein the gearbox assembly further comprises a planetary gear.

23. The electric engine of claim 15 , wherein the gearbox assembly further comprises a ring gear.

24. The electric engine of claim 15 , wherein the gearbox assembly further comprises a planetary carrier.

25. An electric engine for an aircraft, comprising:

an electric motor assembly including a stator and a rotor;

an inverter assembly;

a gearbox assembly including:

a sun gear;

a main shaft including a length of the main shaft that extends from a first end of the main shaft through the gearbox assembly and through the electric motor assembly to a second end of the main shaft; and

a hydrodynamic bearing located between the main shaft and sun gear,

wherein a pump drive gear is configured in association with a planet carrier to drive a pump to flow oil to a heat exchanger, the inverter, the electric motor assembly, and the gearbox assembly.

26. The electric engine of claim 25 , further comprising a bearing including an inner race mechanically coupled to the main shaft and an outer race mechanically coupled to the rotor.

27. The electric engine of claim 26 , wherein the bearing comprises a deep groove ball bearing.

28. The electric engine of claim 26 , wherein the bearing comprises a rolling bearing.

29. The electric engine of claim 25 , wherein the hydrodynamic bearing includes oil.

30. The electric engine of claim 25 , wherein the heat exchanger includes one or more liquid flow paths fluidically coupled to the gearbox assembly and electric motor assembly.

31. The electric engine of claim 30 , wherein the liquid flow paths are configured to allow flow of oil.

32. The electric engine of claim 30 , wherein the hydrodynamic bearing comprises liquid from the one or more liquid flow paths.

33. The electric engine of claim 25 , wherein the main shaft traverses-through the sun gear, wherein the sun gear is hollow.