Parallel hybrid power plant with hollow electric motor

Abstract

A hybrid electric powertrain system for an aircraft includes a gearbox having a first rotational shaft for output to drive a blower for aircraft thrust. The system includes a first prime mover connected to the gearbox through a second rotational shaft for input of power to the gearbox. Further, the system includes a second prime mover connected to the gearbox through a third rotational shaft. The second prime mover can have a hollow core, and at least one of the first rotational shaft and the second rotational shaft passes through the hollow core and the third rotational shaft.

Description

Technical Field

[0001] This disclosure relates to aircraft power systems, and more particularly to hybrid aircraft powertrains. Background Technology

[0002] Aircraft propulsion systems vary in efficiency and function across several parameters, such as thrust requirements, air temperature, air speed, and altitude. Aircraft require maximum thrust during takeoff, placing the greatest demand on engine power. However, for the remainder of the mission, aircraft engines typically do not require the same level of thrust as during takeoff. While the size and weight of engines allow them to generate the power needed for takeoff, after takeoff, the engines are actually too large because the power required to generate thrust for level flight cruise is relatively low.

[0003] Conventional technologies have been deemed sufficient to fulfill their intended purpose. However, there has always been a need for improved aircraft propulsion systems. Summary of the Invention

[0004] A hybrid electric powertrain system for an aircraft includes a gearbox having a first rotating shaft for outputting power to drive a blower to obtain aircraft thrust. The system includes a first prime mover connected to the gearbox via a second rotating shaft for inputting power to the gearbox. Furthermore, the system includes a second prime mover connected to the gearbox via a third rotating shaft. The second prime mover may have a hollow core, and at least one of the first and second rotating shafts passes through the hollow core and the third rotating shaft. A cooling air path may be defined through the hollow core, and a radial air passage receives air from the hollow core, extending radially between the second prime mover and the gearbox and exchanging heat with the second prime mover.

[0005] The first prime mover and the second prime mover can both be located on one side of the gearbox, such that the second prime mover is located between the gearbox and the first prime mover, and the second rotating shaft passes through the hollow core and through the third rotating shaft. Alternatively, the second prime mover and the first prime mover can be located on opposite sides of the gearbox, such that the first rotating shaft passes through the hollow core and through the third rotating shaft.

[0006] The gearbox can be configured to receive rotational power input in parallel from the second and third rotating shafts, and output rotational power to the first rotating shaft, such that the power from either or both of the second and first prime movers can power the first prime mover.

[0007] The gearbox may include a planetary gear set comprising a sun gear connected to drive the first rotating shaft, an internal ring gear connected to receive input from the third rotating shaft, and a set of planetary gears meshing between the internal ring gear and the sun gear. All planetary gears may be connected to a support frame connected to receive input from the second rotating shaft.

[0008] The first shaft can be connected to a blower, wherein the blower is positioned to move air through the cooling path. The second prime mover can be an electric propulsion unit, which can include a stator fixed relative to the gearbox and a rotor within the stator, wherein the rotor is connected to the third rotating shaft to provide rotational input to the gearbox. Multiple spokes can connect the rotor to the third rotating shaft.

[0009] The first prime mover can be a heat engine. The second prime mover can be an electric motor. The gearbox can be configured to provide a predetermined output speed to the first rotating shaft in at least one of the following situations: the second rotating shaft provides power input to the gearbox at a first input speed, and the third rotating shaft simultaneously provides power input to the gearbox at the first input speed; and / or the second rotating shaft provides power input to the gearbox at a second input speed, and the third rotating shaft simultaneously provides power input to the gearbox at a third input speed different from the second input speed.

[0010] One method includes, in a hybrid electric drive system, using a first prime mover and a second prime mover to drive a gearbox to drive a blower to obtain aircraft thrust, wherein the first prime mover and the second prime mover provide power input to the gearbox in parallel. Driving the gearbox includes delivering power input from the first prime mover to the gearbox via a hollow core of the second prime mover.

[0011] The method can include cooling the second prime mover using an airflow through the hollow core. Cooling the second prime mover using an airflow can include driving air into the hollow core using the blower.

[0012] All thrust can be provided by the first prime mover, while the second prime mover can remain idle during cruise. During takeoff and climb, both the first and second prime movers can contribute all the power required by the aircraft to the gearbox. Both the first and second prime movers contribute a portion of the power, but not equally to each other, to drive the gearbox.

[0013] The second prime mover can be an electric motor, so the method can also include using power from the first prime mover during battery recharging on the ground or driving the electric motor in generator mode by rotating the propeller during flight. The second prime mover can be an electric motor, so the method can also include using power input from the electric motor to the gearbox to drive the first prime mover to start it.

[0014] These and other features of the systems and methods of this disclosure will become more readily apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings. Attached Figure Description

[0015] Therefore, those skilled in the art will readily understand how to make and use the apparatus and methods of this disclosure without excessive experimentation. Embodiments of the apparatus and methods will be described in detail below with reference to specific figures, wherein:

[0016] Figure 1 This is a schematic diagram of an embodiment of a system constructed according to the present disclosure, showing multiple prime movers connected to a blower via a gearbox;

[0017] Figure 2 yes Figure 1 A schematic diagram of the system implementation plan is shown. Figure 1 The configuration of the prime mover relative to the gearbox; and

[0018] Figure 3 It is a schematic block diagram of a method according to at least one aspect of this disclosure. Detailed Implementation

[0019] Reference will now be made to the figures, in which the same reference numerals label similar structural features or aspects of this disclosure. For illustrative and diagrammatic purposes and without limitation, partial views of embodiments of the system according to this disclosure are shown in... Figure 1 The diagram is shown and generally marked with reference character 100. Other embodiments or aspects of the system according to this disclosure will be described as follows. Figures 2 to 3 The systems and methods described herein can be used in many different applications. Among other applications, the systems and methods described herein can be used as prime movers for power plants.

[0020] System 100 (e.g., a hybrid electric powertrain for an aircraft) can include a gearbox 102 having a first rotating shaft 104 for outputting power to drive a blower 106 to obtain aircraft thrust. In some embodiments, such as this embodiment, the blower 106 is a propeller. In other embodiments, the blower 106 is contemplated to be of a different type, such as, but not limited to, a helicopter rotor. System 100 can include a first prime mover 108 connected to the gearbox 102 via a second rotating shaft 110 for inputting power to the gearbox 102.

[0021] Furthermore, system 100 may include a second prime mover 112 connected to gearbox 102 via a third rotating shaft 114. The second prime mover 112 may have a hollow core 116, and at least one of the first and second rotating shafts 104, 110 may pass through the hollow core 116 and the third rotating shaft 114. A cooling air path 118 may pass through the hollow core 116 and is defined, for example, through a radial air passage 120 downstream of the hollow core 116. Air may flow through the radial air passage 120 and exit radially between the second prime mover 112 and gearbox 102, such that the radial air passage 120 may exchange heat with the second prime mover 112, for example, for cooling the second prime mover 112.

[0022] In the implementation plan, for example Figure 2 In the example shown, the first prime mover 108 and the second prime mover 112 can both be on one side of the gearbox 102, for example, on a common lateral side. In this case, the second prime mover 112 can be located between the gearbox 102 and the first prime mover 108, and the second rotating shaft 110 can pass through the hollow core 116 and through the third rotating shaft 114. However, it is also possible, as in... Figure 1 In the example shown, the second prime mover 112 and the first prime mover 108 are located on opposite lateral sides of the gearbox 102. There, the first rotating shaft 104 can pass through the hollow core 116 and through the third rotating shaft 114.

[0023] Gearbox 102 can be configured to receive rotational power input in parallel from the second and third rotating shafts 110, 114, and output rotational power to the first rotating shaft 104, such that power from either or both of the second prime mover 112 and the first prime mover 108 can power the blower 106 via the first rotating shaft 104. Gearbox 102 can include a planetary gear set 122, which includes a sun gear 124, an internal ring gear 126, and a set of planetary gears 128. The sun gear 124 can be connected to drive the first rotating shaft 104, the internal ring gear 126 can be connected to receive input from the third rotating shaft 114, and the planetary gears 128 can mesh between the internal ring gear 126 and the sun gear 124. All planetary gears 128 can be connected to a bracket 130, which can be connected to receive input from the second rotating shaft 110.

[0024] Still referencing Figure 1 A first shaft 104 can be connected to a blower 106, wherein the blower 106 is positioned to move air through a cooling path 118. A second prime mover 112 can be an electric propulsion unit, which can include a stator 132 fixedly mounted relative to the gearbox 102 and a rotor 134 within the stator 132. The rotor 134 can be connected to a third rotating shaft 114 to provide rotational input to the gearbox 102. To retain the hollow core 116, a plurality of spokes 136 can connect the rotor 134 to the third rotating shaft 114.

[0025] In the implementation scheme, the first prime mover 108 can be a heat engine, and the second prime mover 112 can be an electric motor. When the second prime mover 112 is an electric motor, it can also function as a generator configured to recharge an electrical energy storage device. Therefore, even when the power input from the second and third rotating shafts 110 and 114 is provided at two different speeds, the gearbox 102 can be configured to provide a predetermined output speed to the first rotating shaft 104. For example, the second rotating shaft 110 can provide input to the gearbox 102 at a first rotational speed, and the third rotating shaft 114 can provide input to the gearbox 102 at a second rotational speed, which is different from the first rotational speed.

[0026] Method 200 according to this technology can include, in a hybrid electric drive system, driving gearbox 102 with a first prime mover 108 and a second prime mover 112 to drive blower 106 to obtain aircraft thrust, wherein the first prime mover and the second prime mover 108, 112 are parallel, as shown in block 202. Method 200 can include, in block 204, cooling the second prime mover 112 using an airflow through hollow core 116. Cooling the second prime mover 112 using an airflow can include, in block 206, driving air into hollow core 116 with blower 106. For example, cooling can be achieved by driving air into hollow core 116 because propeller flushing from a propeller (e.g., blower 106) connected to the rotating output end of gearbox 102 flows downstream of the propeller toward the second prime mover 112.

[0027] In method 200, all thrust can be provided by the first prime mover 108, while the second prime mover 112 can remain idle during cruise. During takeoff and climb, both the first and second prime movers 108 and 112 can contribute all the power required by the aircraft to the gearbox 102. Alternatively, both the first and second prime movers 108 and 112 can contribute a portion of the power, but not equally to each other, to drive the gearbox 102.

[0028] If the second prime mover 112 is an electric motor, method 200 may also include, in block 208, using power from the first prime mover 108 during battery recharging on the ground or in generator mode by rotating the propeller during flight. When the second prime mover 112 is an electric motor, method 200 may also include, in block 210, using power input from the electric motor to gearbox 102 to drive a second rotating shaft to start the first prime mover 108.

[0029] For example, the hybrid power unit of system 100 described above can combine power inputs from two different sources, such as a thermal engine and an electric motor (e.g., prime movers 108, 112). The thermal engine and the electric motor operate at different speeds. It is possible for the hybrid power unit to be installed in a parallel or series configuration; however, a parallel configuration offers its own advantages. For example, a long cylindrical and parallel configuration can be more easily fitted within an aircraft cabin. Furthermore, a parallel configuration allows the propeller to be independently driven by either prime mover 108, 112 or a combination of the prime movers.

[0030] The prime movers 108 and 112 can be electric motors and / or thermal engines as described herein; however, those skilled in the art will understand that the prime movers are not limited to these two possibilities. As mentioned above, the prime mover and the blower are mechanically connected via a planetary gear system. The planetary gear system can be designed with specific combinations of gear ratios to convert two different speed inputs to achieve a desired output speed. While conventional planetary gear systems can be used, the arrangement of a hollow-core electric motor within the hybrid power unit allows for improved cooling of the electric prime mover.

[0031] Hybrid power plants add extra weight to aircraft and occupy more space than conventional systems, making it crucial to create a compact hybrid power plant layout without sacrificing functionality and maintenance access. For example, electric motors need to be compact and have a high power-to-weight ratio. Typically, for AC motors, the stator with windings is filled with coolant. However, in hybrid systems, the magnets within the rotor also need to be cooled; otherwise, as temperatures rise, the magnets may demagnetize, thus reducing the overall efficiency of the motor. Conventional cooling techniques used for AC motors are unsuitable for the hybrid power systems described.

[0032] Therefore, by using a hollow core, such as the hollow core 116 described above, the motor can have a larger diameter, thus providing more space for the stator windings, while the rotor has increased surface area exposed to ambient air for cooling. Natural or forced convection of air from a blower, for example, would be a cost-effective solution for cooling the magnets in the rotor, thereby expanding the availability of magnets.

[0033] The methods and systems of this disclosure, as described above and illustrated in the figures, provide improved cooling within hybrid power units. While the devices and methods of this disclosure have been shown and described, those skilled in the art will readily understand that variations and / or modifications can be made to the devices and methods without departing from the scope of this disclosure.

Claims

1. A hybrid electric powertrain system for an aircraft, the system comprising: A gearbox having a first rotating shaft for outputting to drive a blower to obtain aircraft thrust; A first prime mover, connected to the gearbox via a second rotating shaft for inputting power to the gearbox; and A second prime mover, connected to the gearbox via a third rotating shaft, wherein the second prime mover has a hollow core, and wherein at least one of the first and second rotating shafts passes through the hollow core and the third rotating shaft. The second prime mover is an electric propulsion unit, which includes a stator fixedly mounted relative to the gearbox and a rotor within the stator, and the rotor is connected to the third rotating shaft to achieve rotational input to the gearbox. Multiple spokes connect the rotor to the third rotating shaft.

2. The system of claim 1, wherein the first prime mover and the second prime mover are both on one side of the gearbox, the second prime mover is between the gearbox and the first prime mover, and the second rotating shaft passes through the hollow core and through the third rotating shaft.

3. The system of claim 1, wherein the second prime mover and the first prime mover are on opposite sides of the gearbox, and the first rotating shaft passes through the hollow core and through the third rotating shaft.

4. The system of claim 1, wherein the gearbox is configured to receive rotational power input in parallel from the second and third rotating shafts, and to output rotational power to the first rotating shaft such that power from either or both of the second and first prime movers can power the first rotating shaft.

5. The system of claim 1, wherein the gearbox comprises a planetary gear set including a sun gear connected to drive the first rotating shaft, an internal gear ring connected to receive input from the third rotating shaft, and a set of planetary gears meshing between the internal gear ring and the sun gear, wherein all the planetary gears are connected to a support, the support being connected to receive input from the second rotating shaft.

6. The system of claim 1, wherein the first prime mover is a heat engine.

7. The system of claim 1, wherein the second prime mover is an electric motor.

8. The system of claim 1, wherein the gearbox is configured to provide a predetermined output speed to the first rotating shaft in at least one of the following situations: The second rotating shaft provides power input to the gearbox at a first input speed, and the third rotating shaft simultaneously provides power input to the gearbox at the first input speed, and / or The second rotating shaft provides power input to the gearbox at a second input speed, and the third rotating shaft simultaneously provides power input to the gearbox at a third input speed, which is different from the second input speed.

9. A hybrid electric powertrain system for an aircraft, the system comprising: A gearbox having a first rotating shaft for outputting to drive a blower to obtain aircraft thrust; A first prime mover, connected to the gearbox via a second rotating shaft for inputting power to the gearbox; and A second prime mover, connected to the gearbox via a third rotating shaft, wherein the second prime mover has a hollow core, and wherein at least one of the first and second rotating shafts passes through the hollow core and the third rotating shaft. The cooling air path is defined through the hollow core, and a radial air channel receives air from the hollow core, the radial air channel extending radially between the second prime mover and the gearbox and exchanging heat with the second prime mover.

10. The system of claim 9, wherein the first rotating shaft is connected to the blower, wherein the blower is positioned to move air through the cooling air path.

11. A method for operating a hybrid electric drive system, the method comprising: In a hybrid electric drive system, a first prime mover and a second prime mover drive a gearbox to drive a blower to obtain aircraft thrust. The first prime mover and the second prime mover provide power input to the gearbox in parallel, wherein driving the gearbox includes delivering power input from the first prime mover to the gearbox via the hollow core of the second prime mover. The second prime mover is an electric propulsion device, which includes a stator fixedly mounted relative to the gearbox and a rotor within the stator, wherein a plurality of spokes connect the rotor to a rotating shaft, the rotating shaft connecting the second prime mover to the gearbox, and the rotor being connected to the rotating shaft to achieve rotational input to the gearbox.

12. The method of claim 11, further comprising cooling the second prime mover by means of an airflow through the hollow core.

13. The method of claim 12, wherein using an airflow to cool the second prime mover comprises driving air into the hollow core using the blower.

14. The method of claim 11, wherein all the thrust is provided by the first prime mover and the second prime mover is idle during cruise.

15. The method of claim 11, wherein during takeoff and climb, the first prime mover and the second prime mover each contribute all the power required by the aircraft to the gearbox.

16. The method of claim 11, wherein the first prime mover and the second prime mover each contribute a portion of the power, but not equally relative to each other, to drive the gearbox.

17. The method of claim 11, wherein the second prime mover is an electric motor, and the method further comprises: The electric motor is driven in generator mode by using power from the first prime mover during battery recharging on the ground or by rotating the propeller during flight.

18. The method of claim 11, wherein the second prime mover is an electric motor, and the method further comprises: The first prime mover is started by using the power input from the electric motor to the gearbox.

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