Systems and methods for oil management in gearboxes for eVTOL aircraft
An electric propulsion system for a vertical take-off and landing (VTOL) aircraft having a heat exchanger to cool fluids used in an electrical engine, the electric propulsion system comprising at least one electrical engine mechanically connected directly or indirectly to a fuselage of the VTOL aircraft and electrically connected to an electrical power source. The electrical engine may comprise an electrical motor having a stator and a rotor; a gearbox assembly comprising a sun gear; at least one planetary gear; a ring gear; and a planetary carrier. The electric engine may include an inverter assembly comprising a thermal plate and an inverter assembly housing; an end bell assembly that is connected to the thermal plate of the inverter assembly; and a heat exchanger comprising an array of cooling fins and tubes.
1. An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, the electric propulsion system comprising:
at least one electrical engine configured to be mechanically connected directly or indirectly to a fuselage of the VTOL aircraft and electrically connected to an electrical power source, wherein the electrical engine comprises:
a gearbox assembly comprising:
at least one planetary gear;
a pump drive gear;
a planetary carrier;
a carrier cover that is mechanically coupled to the planetary carrier; and
an end bell assembly comprising a pump rotor that interfaces with the pump drive gear;
a motor-gearbox housing comprising a fluid reservoir; and
a heat exchanger, wherein the gearbox assembly, end bell assembly, and motor-gearbox housing are concentrically aligned with a main shaft of the electrical engine.
2. The system of claim 1 , wherein the pump drive gear is configured to drive the pump rotor to transfer a fluid from the fluid reservoir to the heat exchanger through a fluid inlet in the fluid reservoir.
3. The system of claim 1 , wherein the pump drive gear is mechanically coupled to the planetary carrier.
4. The system of claim 1 , wherein the pump drive gear is positioned between the planetary carrier and the carrier cover.
5. The system of claim 1 , wherein the at least one planetary gear comprises a compound planetary gear, wherein the compound planetary gear comprises at least two planetary gears concentrically aligned on a shared shaft.
6. The system of claim 5 , wherein the pump drive gear is positioned between the at least two planetary gears of the compound planetary gear.
7. The system of claim 1 , wherein the pump rotor is configured to pump a fluid from the fluid reservoir at a flow rate that is proportional to a speed of rotation of a propeller assembly, wherein the propeller assembly is mechanically coupled to the main shaft.
8. The system of claim 1 , wherein the end bell assembly further comprises:
a plate;
a first circular wall extending from the plate; and
a second circular wall extending from the plate, wherein a diameter of the second circular wall is less than a diameter of the first circular wall.
9. The system of claim 1 further comprising an area defined by a first circular wall of the end bell assembly and the motor-gearbox housing, wherein the area defines the fluid reservoir.
10. The system of claim 9 , wherein the area is concentrically aligned with the main shaft.
11. The system of claim 1 , wherein the pump drive gear is mechanically coupled to the planetary carrier and the carrier cover.
12. The system of claim 1 , wherein the pump drive gear is concentrically aligned with the main shaft.
13. An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, the electric propulsion system comprising:
at least one electrical engine configured to be mechanically connected directly or indirectly to a fuselage of the VTOL aircraft and electrically connected to an electrical power source, wherein the electrical engine comprises:
an electrical motor comprising a stator and a rotor;
a gearbox assembly comprising:
at least one planetary gear;
a pump drive gear; a planetary carrier;
a carrier cover that is mechanically coupled to the planetary carrier; and
an end bell assembly comprising a pump rotor that interfaces with the pump drive gear;
an inverter assembly configured to provide alternating current to the electric motor;
a motor-gearbox housing comprising a fluid reservoir, wherein the gearbox assembly and electrical motor are located in the motor-gearbox housing; and
a heat exchanger.
14. The system of claim 13 , further comprising an inverter assembly housing, wherein the heat exchanger is mounted to the inverter assembly housing.
15. The system of claim 14 , wherein the pump drive gear is configured to drive the pump rotor to transfer a fluid from the fluid reservoir to the heat exchanger through a fluid inlet in the reservoir.
16. The system of claim 13 , wherein the pump drive gear is mechanically coupled to the planetary carrier.
17. The system of claim 13 , wherein the pump drive gear is positioned between the planetary carrier and the carrier cover.
18. The system of claim 13 , wherein the at least one planetary gear comprises a compound planetary gear, wherein the compound planetary gear comprises at least two planetary gears concentrically aligned on a shared shaft.
19. The system of claim 18 , wherein the pump drive gear is positioned between the at least two planetary gears of the compound planetary gear.
20. The system of claim 13 , wherein the pump rotor is configured to pump a fluid from the fluid reservoir at a flow rate that is proportional to a speed of rotation of the at least one planetary gear.
21. A method of operating an electric propulsion system for a vertical take-off and landing (VTOL) aircraft, the method comprising:
operating at least one electrical engine configured to be mechanically connected directly or indirectly to a fuselage of the VTOL aircraft and electrically connected to an electrical power source, wherein the electrical engine comprises:
a gearbox assembly comprising:
at least one planetary gear;
a pump drive gear;
a planetary carrier;
a carrier cover that is mechanically coupled to the planetary carrier; and
an end bell assembly comprising a pump rotor that interfaces with the pump drive gear;
a motor-gearbox housing comprising a fluid reservoir; and
a heat exchanger, wherein the gearbox assembly, end bell assembly, and motor-gearbox housing are concentrically aligned with a main shaft of the electrical engine; and
transferring a fluid from the fluid reservoir to the heat exchanger by operation of the pump drive gear.
22. The method of claim 21 , wherein the pump drive gear is configured to drive the pump rotor to transfer the fluid from the fluid reservoir to the heat exchanger through a fluid inlet in the fluid reservoir.
23. The method of claim 21 , wherein the pump drive gear is mechanically coupled to the planetary carrier.
24. The method of claim 21 , wherein the pump drive gear is positioned between the planetary carrier and the carrier cover.
25. The method of claim 21 , wherein the at least one planetary gear comprises a compound planetary gear, wherein the compound planetary gear comprises at least two planetary gears concentrically aligned on a shared shaft.
26. The method of claim 25 , wherein the pump drive gear is positioned between the at least two planetary gears of the compound planetary gear.
27. The method of claim 25 , wherein the pump rotor is configured to pump a fluid from the fluid reservoir at a flow rate that is proportional to a speed of rotation of a propeller assembly, wherein the propeller assembly is mechanically coupled to the main shaft.
28. The method of claim 25 , wherein the pump drive gear is mechanically coupled to the planetary carrier and the carrier cover.
29. The method of claim 25 , wherein the pump drive gear is concentrically aligned with the main shaft.