Dual hybrid propulsion system for aircraft with cross-connected clutch

Abstract

The present application discloses a dual hybrid propulsion system for an aircraft with a cross-connected clutch. A propulsion system for an aircraft includes a first propeller, a second propeller, a first hybrid propulsion system, a second hybrid propulsion system, and a cross-connected clutch. The first hybrid propulsion system includes a first motor coupled to a first engine through a first overrunning clutch, wherein the first hybrid propulsion system is operably coupled to drive the first propeller. The second hybrid propulsion system includes a second motor coupled to a second engine through a second overrunning clutch, wherein the second hybrid propulsion system is operably coupled to drive the second propeller. The cross-connected clutch is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system and is configured to actuate to an engaged position.

Description

Technical Field

[0001] The present disclosure relates to a propulsion system for an aircraft. More specifically, the present disclosure is directed to an aircraft propulsion system having a first hybrid propulsion system operably coupled to a first propeller, a second hybrid propulsion system operably coupled to a second propeller, and a cross-connect clutch. Background Art

[0002] Commuter aircraft are typically small in size, carry a limited number of passengers, and can be used to travel relatively short distances. Commuter aircraft may be powered by a propeller, or alternatively by a gas turbine, also known as a jet engine. Typically, propeller-driven aircraft are typically used for short-distance flights, while gas turbines are used for longer distance flights. For example, propeller-driven aircraft may be used to transport super commuters between their residence and workplace. Some super commuters may live in a different geographic area from their workplace, while other super commuters live outside or in the suburbs of the metropolitan area where their workplace is located. Therefore, propeller-driven aircraft may be frequently used to transport commuters between their residence and workplace. Summary of the invention

[0003] According to several aspects, a propulsion system for an aircraft is disclosed. The propulsion system includes a first propeller and a second propeller. The propulsion system also includes a first hybrid propulsion system, the first hybrid propulsion system including a first motor coupled to a first engine through a first overrunning clutch, wherein the first hybrid propulsion system is operably coupled to the first propeller to drive the first propeller. The propulsion system also includes a second hybrid propulsion system, the second hybrid propulsion system including a second motor coupled to a second engine through a second overrunning clutch, wherein the second hybrid propulsion system is operably coupled to the second propeller to drive the second propeller. The propulsion system also includes a cross-connecting clutch, the cross-connecting clutch is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system and is configured to actuate to an engaged position.

[0004] In another aspect, a method for operating a propulsion system for an aircraft is disclosed. The method includes monitoring the operation of a first engine and a second engine through a control module. The first engine is part of a first hybrid propulsion system operably coupled to a first propeller, and the second engine is part of a second hybrid propulsion system operably coupled to a second propeller. The method includes determining through the control module that the first engine or the second engine is not outputting the amount of torque required to maintain a desired flight phase. The first hybrid propulsion system includes a first motor coupled to the first engine through a first overrunning clutch, and the second hybrid propulsion system includes a second motor coupled to the second engine through a second overrunning clutch. In response to determining that the first engine or the second engine is not outputting the required torque, the method includes instructing the cross-connect clutch to actuate from a disengaged position to an engaged position.

[0005] In yet another aspect, an aircraft is disclosed. The aircraft includes a cabin, a first propeller and a second propeller, wherein the first propeller and the second propeller are attached to and positioned on opposite sides of the cabin. The aircraft also includes a first hybrid propulsion system, the first hybrid propulsion system includes a first motor coupled to a first engine through a first overrunning clutch, wherein the first hybrid propulsion system is operably coupled to the first propeller to drive the first propeller. The aircraft also includes a second hybrid propulsion system, the second hybrid propulsion system includes a second motor coupled to a second engine through a second overrunning clutch, wherein the second hybrid propulsion system is operably coupled to the second propeller to drive the second propeller. The aircraft also includes a cross-connection clutch, the cross-connection clutch is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system, and is configured to actuate to an engagement position. When the second engine does not output the torque required to maintain the desired flight phase of the aircraft, engaging the cross-connection clutch causes the first hybrid propulsion system to drive the second propeller, and when the first engine does not output the torque required to maintain the desired flight phase of the aircraft, engaging the cross-connection clutch causes the second hybrid propulsion system to drive the first propeller.

[0006] The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0008] Figure 1 is a cross-sectional side view of a propulsion system for an aircraft according to an exemplary embodiment, wherein the propulsion system includes a first hybrid propulsion system, a second hybrid propulsion system, and a cross-connect clutch;

[0009] Figure 2 According to an exemplary embodiment Figure 1 A schematic diagram of the propulsion system shown;

[0010] Figure 3A According to an exemplary embodiment, Figure 2 A schematic diagram of a first arrangement of individual batteries of a portion of a battery pack is shown;

[0011] Figure 3B is a schematic diagram of a second arrangement of individual batteries as part of a battery pack according to an exemplary embodiment;

[0012] Figure 4 According to an exemplary embodiment Figure 1 an enlarged view of the final drive gearbox shown; and

[0013] Figure 5A and 5B is a process flow diagram illustrating a method of operating the disclosed propulsion system according to an exemplary embodiment. DETAILED DESCRIPTION

[0014] The present disclosure is directed to a propulsion system for a propeller-driven aircraft. The aircraft includes a first hybrid propulsion system that is operably coupled to a first propeller and drives the first propeller. The aircraft also includes a second hybrid propulsion system that is operably coupled to a second propeller and drives the second propeller. The aircraft also includes a cross-connected clutch that is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system. When the cross-connected clutch is in an engaged position, the first hybrid propulsion system drives both the first propeller and the second propeller. Similarly, when the clutch is in an engaged position, the second hybrid propulsion system drives both the first propeller and the second propeller. Therefore, in the event that one of the two hybrid propulsion systems cannot operate, both propellers can still be driven.

[0015] In addition, each hybrid system includes an engine, a motor, and an overrunning clutch that operably couples the engine to the motor. The overrunning clutch is configured to engage when the torque generated by the engine exceeds the torque generated by the motor (e.g., when the engine is initially started). In addition, the size of the engine of each hybrid propulsion system is designed to adapt to the power requirements of the aircraft during the cruise phase of flight. For other flight phases other than cruising (e.g., during the climb phase of flight), the motor can be used to increase the torque generated by the engine so that the torque provided to the propeller is the sum of the torque provided by the engine and the motor. In comparison, a conventional system may have an engine whose size is adapted to the climb phase of flight.

[0016] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0017] refer to Figure 1 , a propulsion system 10 for an aircraft 12 is shown. The aircraft 12 is a propeller-driven aircraft and, as such, includes a first propeller 20A and a second propeller 20B attached to and positioned on opposite sides 14 of a cabin 16. The propulsion system 10 includes a first hybrid propulsion system 22A, a second hybrid propulsion system 22B, a cross-connect clutch 26, an exhaust system 28, a tail cone fan 30, and a control module 32 in electronic communication with the cross-connect clutch 26. The first hybrid propulsion system 22A, the second hybrid propulsion system 22B, the cross-connect clutch 26, and the exhaust system 28 are all positioned within the cabin 16 of the aircraft 12. The first hybrid propulsion system 22A is operably coupled to the first propeller 20A and drives the first propeller. Similarly, the second hybrid propulsion system 22B is operably coupled to the second propeller 20B and drives the second propeller.

[0018] The first hybrid propulsion system 22A includes a first engine 36A, a first motor 38A, a first overrunning clutch 40A, and a first turbocharger 42A. The first overrunning clutch 40A couples the first engine 36A and the first motor 38A to each other when engaged, and disengages the first engine 36A from the first motor 38A when disengaged. When the first overrunning clutch 40A is engaged, the first engine 36A and the first motor 38A are part of a torque summing arrangement. The first overrunning clutch 40A and the second overrunning clutch 40B are one-way overrunning clutches, such as sprag clutches.

[0019] The first overrunning clutch 40A is connected to the output 44A of the first engine 36A and the input of the first motor 38A (not shown). The output 46A of the first motor 38A is connected to the first final drive gearbox 48A. Similarly, the second hybrid propulsion system 22B includes the second engine 36B, the second motor 38B, the second overrunning clutch 40B and the second turbocharger 42B. The second overrunning clutch 40B is connected to the output 44B of the second engine 36B and the input of the second motor 38B (not shown). The output 46B of the second motor 38B is connected to the second final drive gearbox 48B.

[0020] In such Figure 1In the non-limiting embodiment shown, the first engine 36A and the second engine 36B are shown as turbocharged six-cylinder in-line diesel engines. In a specific embodiment, the engines 36A and 36B are compression ignition (i.e., diesel) four-stroke engines, because compression ignition engines are more efficient than spark ignition engines. However, it should be understood that the engines 36A, 36B are not limited to compression ignition engines. In alternative embodiments, the engines 36A, 36B are spark ignition engines. In addition, although a four-stroke engine is mentioned, a two-stroke engine may also be used. A two-stroke engine tends to have a lower maintenance cost because the valve train of a two-stroke engine is more simplified compared to a four-stroke engine. The first motor 38A and the second motor 38B are both electric motors, such as, but not limited to, permanent magnet direct current (DC) motors.

[0021] Sometimes, the first hybrid propulsion system 22A or the second hybrid propulsion system 22B cannot transmit enough power to the corresponding propeller 20A, 20B to maintain the aircraft 12 in the desired flight phase. Specifically, the control module 32 is in electronic communication with both the first engine 36A and the second engine 36B, and monitors the operation of the first engine 36A and the second engine 36B in real time. The control module 32 may refer to an electronic circuit, a combinational logic circuit, a field programmable gate array (FPGA), a processor (shared, dedicated or grouped) that executes instructions and codes, or a combination of some or all of the above, or be part of it, such as in a system on a chip.

[0022] In operation, the control module 32 determines when the first engine 36A or the second engine 36B is not outputting the required amount of torque. For example, the first engine 36A or the second engine 36B may become inoperable due to a loss of oil pressure. In response to determining that the first engine 36A or the second engine 36B is not outputting the required amount of torque, the control module 32 instructs the cross-connected clutch 26 to actuate from a disengaged position to an engaged position. When the cross-connected clutch 26 is engaged, the first hybrid propulsion system 22A is operably coupled to both the first propeller 20A and the second propeller 20B. Therefore, when the cross-connected clutch 26 is engaged, the first hybrid propulsion system 22A drives both the propellers 20A, 20B. Similarly, when the cross-connected clutch 26 is engaged, the second hybrid propulsion system 22B is operably coupled to drive both the first propeller 20A and the second propeller 20B. In an exemplary embodiment, the cross-connect clutch 26 is a plate clutch that is coupled to the first and second propellers 20A, 20B through respective gearboxes 48A, 48B, 50A, 50B and is described in greater detail below.

[0023] The operation of overrunning clutch 40A and 40B is now described. The first overrunning clutch 40A and the second overrunning clutch 40B are engaged based on the difference between the torque produced by corresponding engine 36A, 36B and motor 38A, 38B. Specifically, when the engine torque of the first engine 36A is greater than the motor torque of the first motor 38A, the first overrunning clutch 40A is engaged. For example, when the first engine 36A is turned on, the engine torque of the first engine 36A is greater than the motor torque of the first motor 38A. Therefore, when the aircraft 12 is operated in the climbing phase of flight, the first overrunning clutch 40A remains engaged. Similarly, when the engine torque of the second engine 36B is greater than the motor torque of the second motor 38B (for example, when the second engine 36B is started, or when the aircraft 12 is in the climbing phase of flight), the second overrunning clutch 40B is engaged. The first overrunning clutch 40A and the second overrunning clutch 40B are both configured to disengage when the engine torque is zero or substantially zero, for example, when the rotational speed of the engine output ends 44A, 44B is less than the rotational speed of the shafts of the corresponding motors 38A, 38B, for example, when the first engine 36A or the second engine 36B is turned off.

[0024] The control module 32 is in electronic communication with the two motors 38A, 38B. The control module 32 sends mode signals 58A, 58B to the respective motors 38A, 38B, which instruct the motors 38A, 38B to operate in a power mode or a regeneration mode. The control module 32 instructs the motors 38A, 38B to operate in a power mode or a regeneration mode based on the flight phase of the aircraft 12, which in one example can be inferred from the throttle position of the engines 36A, 36B, the angle of the stabilizer, etc. For example, a 30 percent throttle position would be considered the cruise phase of flight, while an 80 percent throttle position would be considered the takeoff or climb phase of flight. For example, when the control module 32 determines based on the throttle position that the operator wishes to operate the aircraft 12 in the climb phase of flight, the control module 32 transmits the respective mode signals 58A, 58B to the motors 38A and 38B to switch from the regeneration mode to the power mode. In the power mode, the torque produced by the motors 38A, 38B is added to the torque produced by the respective engines 36A, 36B to drive the respective propellers 20A, 20B.

[0025] When the aircraft 12 needs additional thrust or power (for example, when the aircraft 12 is operating in the climbing phase of flight), the motors 38A and 38B operate in the power mode. When excessive thrust or power is not required, the control module 32 sends mode signals 58A and 58B to the motors 38A and / or 38B to switch from the power mode to the regeneration mode. In the regeneration mode, the motors 38A and 38B are used as generators to charge the battery packs 72A and 72B. In addition, only the torque generated by the corresponding engines 36A and 36B is used for the corresponding respective propellers 20A and 20B. Therefore, when commanded by the control module 32 (for example, when the control module 32 determines that the aircraft 12 is operating in the climbing phase of flight), the first motor 38A and the second motor 38B operate in the power mode. When commanded by the control module 32 (for example, when the control module 32 determines to command the aircraft 12 to operate in the cruise phase of flight), the first motor 38A and the second motor 38B operate in the regeneration mode.

[0026] In an exemplary embodiment, the control module 32 may determine that the pilot has commanded a change in flight phase. For example, the pilot may command a change in flight phase by repositioning the throttle lever of the aircraft 12 and / or moving a stabilizer (not shown) of the aircraft. In response to determining the change in flight phase, the control module 32 determines that the current torque output by the engine 36A and / or 36B is not the amount of torque required to maintain the current flight phase or to achieve a new requested flight phase. In another embodiment, the control module 32 may determine that the first engine 36A or the second engine 36B is inoperable and therefore the aircraft 12 cannot maintain the current flight phase.

[0027] It should be understood that when the motors 38A, 38B are operated in the power mode, the engines 36A, 36B receive assistance from the motors 38A, 38B. Therefore, the size of the engines 36A, 36B is not based on the power requirements of the propellers 20A, 20B during the climb phase of flight. Instead, the size of the engines 36A, 36B is set to accommodate the power requirements of the propellers 20A, 20B during the cruise phase of flight. Because the cruise phase of flight requires less power than the climb phase of flight, the engines 36A, 36B are smaller and lighter than conventional engines that are sized for the power requirements during the climb phase of flight.

[0028] Figure 2 is a schematic diagram of the propulsion system 10. Figure 2As shown, the first hybrid propulsion system 22A and the second hybrid propulsion system 22B are arranged in a parallel configuration. Therefore, when the first motor 38A is operating in the power mode, the first engine 36A and the first motor 38A provide power to the first propeller 20A through torque addition. Similarly, when the second motor 38B is operating in the power mode, the second engine 36B and the second motor 38B provide power to the second propeller 20B through torque addition. It should be understood that compared to the series arrangement, Figure 2 The parallel configuration shown in results in improved power transfer efficiency between the engines 36A, 36B and the respective propellers 20A, 20B, as the series configuration requires energy conversion.

[0029] The propulsion system 10 also includes a first battery pack 72A, a second battery pack 72B, one or more first inverters 74A, and one or more second inverters 74B. The first battery pack 72A is electrically coupled to the first motor 38A and another system within the aircraft 12 (such as, for example, an environmental control system (ECS) 76). The second battery pack 72B is electrically coupled to the second motor 38B and yet another system within the aircraft 12 (such as, for example, a hydraulic system 78).

[0030] like Figure 3A and Figure 3B As shown, the first battery pack 72A and the second battery pack 72B each include a plurality of rechargeable independent batteries 80. For example, the independent battery 80 can be a lithium-ion battery. When the first motor 38A is operated in a power mode, the first battery pack 72A provides power to the first motor 38A. Specifically, the first battery pack 72A generates a DC current, which is converted into an alternating current (AC) by the first converter 74A. It should be understood that the sizes of the first battery pack 72A and the second battery pack 72B are both configured to assist the takeoff of the corresponding engines 36A and 36B. Therefore, in an alternative embodiment, the first battery pack 72A and the second battery pack 72B provide power to the propellers 20A and 20B during the climb, and the first engine 36A and the second engine 36B do not operate during the climb. This method can be used to reduce emissions or reduce noise near an airport.

[0031] When operating in a regenerative mode (e.g., during the cruise phase of flight), the first motor 38A acts as a generator to charge the first battery pack 72A. Recharging the first battery pack 72A during the cruise phase of flight provides various benefits. Specifically, when the first battery pack 72A is charged during the cruise phase of flight, the aircraft 12 does not need to be recharged after landing. When operating in a regenerative mode (e.g., during the cruise phase of flight), the second battery pack 72B is also charged by the second motor 38B.

[0032] Figure 3A and Figure 3BAn exemplary method for switching the arrangement of the battery packs 72A, 72B when the motors 38A, 38B are operating in a regenerative mode (e.g., during a cruise phase of flight) is shown. It should be understood that in an exemplary embodiment, the voltage generated by each battery pack 72A, 72B may be reduced by approximately fifty percent once the aircraft 12 completes the climb phase of flight, compared to the voltage of the battery packs 72A, 72B at the beginning of the climb phase of flight. It should also be noted that the voltage generated by the motors 38A, 38B during the regenerative mode is greater than the voltage generated by each battery pack 72A, 72B to enable successful charging during flight and also enable the motors 38A and 38B to provide power to operate the tail cone fan 30, as described in more detail below. Thus, the arrangement of the individual batteries 80 of the battery packs 72A, 72B changes between a power mode in which the battery packs 72A, 72B provide power and a regenerative mode in which the battery packs 72A, 72B are recharged. The first battery pack 72A and the second battery pack 72B each include a plurality of individual batteries 80 that are recharged during the regeneration mode.

[0033] Figure 3A is an exemplary arrangement of the individual batteries 80 during the climb. Figure 3A In the illustrated embodiment, during the power mode, the plurality of individual batteries 80 are connected to one another in a first arrangement, which may also be referred to as a series arrangement. Figure 3B is an exemplary arrangement of the independent battery 80 during the power mode. Figure 3B In the illustrated embodiment, during the regeneration mode, the plurality of individual batteries 80 are connected to one another in a second arrangement, which may also be referred to as a combined series and parallel arrangement.

[0034] In the non-limiting embodiment shown, each battery pack 72A, 72B includes ten individual batteries 80, each of which generates an individual voltage V n However, it should be understood that any number of independent batteries 80 may be used. Figure 3A In the illustrated embodiment, a plurality of individual cells 80 are each arranged in a series configuration to maximize voltage. Figure 3B The arrangement of the independent battery 80 reduces the voltage to less than that supplied by the motors 38A, 38B ( Figure 1 and Figure 2 )The value of the voltage generated.

[0035] Specific reference Figure 3A , by dividing the independent voltage V generated by each independent battery 80 n The voltages produced by each battery pack 72A, 72B are summed. For example, if each individual battery 80 produces 30 volts (i.e., V n=30 volts), then the voltage generated by each battery pack 72A, 72B is 300 volts. However, if the voltage generated by each motor 38A, 38B during regeneration mode is only 280 volts, the motors 38A, 38B cannot provide charging. Figure 3B As shown in , half of the individual batteries 80 are arranged in a series configuration, and the remaining half of the individual batteries 80 are arranged in a parallel configuration. The individual batteries 80 arranged in the series configuration are placed in parallel with the individual batteries arranged in the parallel configuration, which results in a total voltage of 150 volts.

[0036] Return to reference Figure 1 , the tail cone fan 30 is arranged along the front end 90 of the nacelle 16 and includes a plurality of rotating blades (not shown) that generate an airflow. The electric motor 56 is disposed within the tail cone fan 30 and is powered by a first motor 38A and a second motor 38B when the aircraft 12 is operating in the cruise phase of flight, wherein both motors 38A, 38B are operated in a regenerative mode and are driven by respective engines 36A, 36B. It should be understood that the tail cone fan 30 also provides propulsive power to the aircraft 12. Specifically, the tail cone fan 30 provides propulsive power for two reasons. First, the tail cone fan 30 reduces the ram air drag around the nacelle 16. Specifically, the ram air passes through the nacelle 16 and exits the tail cone fan 30, wherein the ram air flow R Figure 1 Second, the tail cone fan 30 promotes or increases the mass of the external air A introduced into the respective combustion air inlets 94A, 94B of the turbochargers 42A, 42B. The tail cone fan 30 also improves thrust by drawing in boundary air surrounding the nacelle 16. It should be understood that boundary air increases drag.

[0037] The first turbocharger 42A is fluidly connected to the first air intake 96A of the first engine 36A, and the second turbocharger 42B is fluidly connected to the second air intake 96B of the second engine 36B. The turbochargers 42A, 42B compress the external air A. The compressed external air A is then provided to the air intakes 96A, 96B of the respective engines 36A, 36B. The turbochargers 42A, 42B can improve the efficiency of the internal combustion engines by forcing more external air A into the respective internal combustion engines 36A, 36B. The tail cone fan 30 further increases the external air A forced through the engines 36A, 36B.

[0038] The exhaust system 28 includes a first exhaust duct 98A fluidly connected to the outlet manifold 100A of the first engine 36A. The exhaust system 28 also includes a second exhaust duct 98B fluidly connected to the outlet manifold 100B of the second engine 36B. The exhaust gas G exiting the first engine 36A and the second engine 36B travels within their respective exhaust ducts 98A, 98B and travels toward the front end 90 of the nacelle 16 and toward the tail cone fan 30. The tail cone fan 30 is fluidly connected to receive exhaust gas from the first exhaust duct 98A and the second exhaust duct 98B and is driven by the exhaust gas in all flight phases except cruise.

[0039] In one embodiment, the first hybrid propulsion system 22A also includes a first air-oil heat exchanger 110A. Similarly, the second hybrid propulsion system 22B includes a second air-oil heat exchanger 110B. The first air-oil heat exchanger 110A is fluidly connected to an air intake 112A disposed along the rear end 92 of the nacelle 16, and the second air-oil heat exchanger is fluidly connected to an air intake 112B also disposed along the rear end 92 of the nacelle 16. The air-oil heat exchangers 110A, 110B are configured to provide cooling to the respective engines 36A, 36B. In addition to cooling the engines 36A, 36B, the air-oil heat exchangers 110A, 110B provide heated air to the respective exhaust ducts 98A, 98B and also extract thermal energy from the fuel used to power the engines 36A, 36B.

[0040] It should be understood that in an exemplary embodiment, the engines 36A, 36B operate at a speed of approximately 2000 RPM. In addition, it should also be understood that the speed of the propellers 20A, 20B also operates at the same speed as the engines 36A, 36B. Therefore, it should be understood that the speed of the first engine 36A controls the speed of the first propeller 20A, and the speed of the second engine 36B controls the speed of the second propeller 20B. Therefore, it should also be understood that, unlike some hybrid propulsion systems that require planetary gear sets to decouple the speed of the engines from the output, the disclosed propulsion system 10 only requires gearboxes 48A, 48B, 50A, 50B to accommodate the geometry or packaging layout of the propellers 20A, 20B.

[0041] Figure 4 is an enlarged view of one or the final drive gearbox 48A, 48B. Figure 1 and Figure 4, both the first final drive gearbox 48A and the second final drive gearbox 48B include three bevel gears 122A, 122B, 122C. It should be understood that the bevel gears transmit motion between two shafts that are not aligned with each other. Moreover, the bevel gears 122A, 122B, 122C are meshingly engaged with each other at a ratio of 1:1, thereby driving the propellers 20A, 20B at the same speed as the engines 36A, 36B. The driving bevel gear 122A is driven by the output end 46A, 46B of the first motor 38A or the second motor 38B. The driving bevel gear 122A meshes with the remaining two driven bevel gears 122B, 122C. The driven bevel gear 122B drives the cross-connection clutch 26 through the shafts 128A, 128B. The driven bevel gear 122C drives the corresponding propeller 20A, 20B through the connecting shafts 130A, 130B.

[0042] Return to reference Figure 1 The gearbox 50A, 50B also includes bevel gears 132A, 132B for transmitting motion between the connecting shafts 130A, 130B and the corresponding propeller shafts 140A, 140B. It should be understood that the connecting shafts 130A, 130B are arranged vertically relative to their corresponding propeller shafts 140A, 140B. The driving bevel gear 132A is driven by the corresponding connecting shafts 130A, 130B. The driven bevel gear 132B is driven by the driving bevel gear 132A, wherein the driven bevel gear 132B is connected to the corresponding propeller shafts 140A, 140B.

[0043] Reference now Figure 5A and Figure 5B , exemplary process flow diagrams illustrate methods 200 and 300 of operating a propulsion system 10 for an aircraft 12. Specifically, Figure 5A The method 200 depicts the operation of the cross-connect clutch 26 and Figure 5B The operation of the overrunning clutches 40A, 40B is shown. Figure 1 and Figure 5A , the method 200 begins at box 202. In box 202, the control module 32 monitors the operation of the first engine 36A and the second engine 36B, wherein the first engine 36A is part of a first hybrid propulsion system 22A operably coupled to the first propeller 20A, and the second engine 36B is part of a second hybrid propulsion system 22A operably coupled to the second propeller 20B. The method 200 then proceeds to box 204.

[0044] In box 204, the control module 32 determines that the first engine 36A or the second engine 36B is not outputting the amount of torque required to maintain the desired flight phase. As described above, the first hybrid propulsion system 22A includes a first motor 38A coupled to the first engine 36A through a first overrunning clutch 40A, and the second hybrid propulsion system 22B includes a second motor 38B coupled to the second engine 36B through a second overrunning clutch 40B. The method 200 then proceeds to box 206.

[0045] In response to determining that the first engine 36A or the second engine 36B is not outputting the required amount of torque, the control module 32 instructs the cross-connect clutch 26 to actuate from the disengaged position to the engaged position in block 206. Thus, when the second engine 36A is not outputting the torque required to maintain the desired flight phase of the aircraft 12, engaging the cross-connect clutch 26 causes the first hybrid propulsion system 22A to drive the second propeller 20B. Similarly, when the first engine 36A is not outputting the torque required to maintain the desired flight phase of the aircraft 12, engaging the cross-connect clutch 26 causes the second hybrid propulsion system 22B to drive the first propeller 20A. The method 200 then terminates.

[0046] Reference now Figure 1 and Figure 5B , method 300 starts at box 302A and box 302B. It should be understood that box 302A and box 302B are performed simultaneously. In box 302A, when the engine torque of the first engine 36A is greater than the motor torque of the first motor 38A (e.g., when the first engine 36A is started), the first overrunning clutch 40A is engaged. Therefore, during normal operation, during all flight phases of the aircraft 12, the first engine 36A and the first motor 38A are coupled together by the overrunning clutch 40A. Similarly, in box 302B, when the engine torque of the second engine 36B is greater than the motor torque of the second motor 38B (e.g., when the second engine 36B is started), the second overrunning clutch 40B is engaged. Therefore, during all flight phases of the aircraft 12, the second engine 36B and the second motor 38B are also coupled together by the second overrunning clutch 40B.

[0047] As described above, because the respective engines 36A, 36B and motors 38A, 38B are coupled together through respective overrunning clutches 40A, 40B during all phases of flight, the additional torque produced by the motors 38A, 38B during the climb phase of flight enables the engines 36A, 36B to be sized specifically for the cruise phase of flight when the additional torque provided by the motors 38A, 38B is not required. This results in a smaller, lighter engine than a conventional engine that is typically sized for the climb phase of flight.

[0048] With reference to the accompanying drawings in general, the disclosed propulsion system provides various technical effects and advantages. Specifically, when one of the two engines does not produce the torque required to maintain the desired flight phase, the cross-connection clutch is engaged. Therefore, in the case where one of the two hybrid propulsion systems cannot operate, the two propellers can still be driven. In addition, this can also reduce the maintenance costs associated with the engine. Moreover, when the engine torque is greater than the motor torque (for example, when the aircraft is in the climbing phase of flight), the overrunning clutch is engaged to couple the engine and the motor to each other. Therefore, the engine can be smaller and cheaper than other conventional engines whose dimensions are designed to provide all the power required for the aircraft to operate in the climbing phase of flight. It should also be understood that the internal combustion engine provides improved efficiency, which may be particularly advantageous if propeller-driven aircraft are often used. Finally, since the battery pack is charged during the cruising process of the flight, the battery is recharged when the aircraft lands. Therefore, the aircraft does not need to be recharged after completing the flight.

[0049] Furthermore, the present disclosure includes embodiments according to the following clauses:

[0050] Clause 1. A propulsion system for an aircraft, the propulsion system comprising:

[0051] a first thruster and a second thruster;

[0052] a first hybrid propulsion system comprising a first motor coupled to the first engine via a first overrunning clutch, wherein the first hybrid propulsion system is operably coupled to drive a first propeller;

[0053] a second hybrid propulsion system comprising a second motor coupled to the second engine via a second overrunning clutch, wherein the second hybrid propulsion system is operably coupled to drive a second propeller; and

[0054] A cross-connect clutch is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system and is configured to be actuated to an engaged position.

[0055] Clause 2. A propulsion system according to clause 1, wherein the first overrunning clutch is engaged when the engine torque of the first engine is greater than the motor torque of the first motor, and wherein the second overrunning clutch is engaged when the engine torque of the second engine is greater than the motor torque of the second motor.

[0056] Clause 3. The propulsion system of clause 1, wherein the first motor and the second motor are operated in a power mode of operation during a climb phase of flight of the aircraft and in a regeneration mode during a cruise phase of flight of the aircraft.

[0057] Clause 4. The propulsion system of clause 1, wherein the first overrunning clutch is disengaged when the engine torque of the first engine is zero, and wherein the second overrunning clutch is disengaged when the engine torque of the second engine is zero.

[0058] Clause 5. The propulsion system of clause 1, wherein the first engine and the first motor are coupled together by a first overrunning clutch during all flight phases, and the second engine and the second motor are coupled together by a second overrunning clutch during all flight phases.

[0059] Clause 6. The propulsion system of clause 1, wherein the speed of the first engine controls the speed of the first propeller, and the speed of the second engine controls the speed of the second propeller.

[0060] Clause 7. The propulsion system of clause 1, wherein the first engine and the second engine are compression ignition engines.

[0061] Clause 8. The propulsion system of Clause 1, further comprising a first turbocharger fluidly connected to a first air intake of the first engine and a second turbocharger fluidly connected to a second air intake of the second engine.

[0062] Clause 9. The propulsion system of clause 1, further comprising a first exhaust conduit fluidly connected to the first engine and a second exhaust conduit fluidly connected to the second engine.

[0063] Clause 10. The propulsion system of clause 9, further comprising a tail cone fan fluidly connected to receive exhaust gas from the first exhaust duct and the second exhaust duct.

[0064] Clause 11. The propulsion system of clause 1, further comprising a control module in electronic communication with the cross-connected clutch, wherein the control module instructs the cross-connected clutch to actuate to the engaged position.

[0065] Clause 12. The propulsion system of clause 11, wherein the control module executes instructions to:

[0066] determining that the first engine or the second engine is not outputting an amount of torque required to maintain a desired phase of flight; and

[0067] In response to determining that the first engine or the second engine is not outputting the desired amount of torque, actuation of the cross-connect clutch from a disengaged position to an engaged position is instructed.

[0068] Clause 13. The propulsion system of clause 1, further comprising a first battery pack electrically coupled to the first motor and a second battery pack electrically coupled to the second motor.

[0069] Clause 14. The propulsion system of Clause 13, wherein both the first battery pack and the second battery pack include a plurality of individual batteries that are recharged during a cruise phase of flight.

[0070] Clause 15. The propulsion system of clause 14, wherein the plurality of independent batteries are connected to each other in a first arrangement during a climb phase of flight and are connected to each other in a second arrangement during a cruise phase of flight.

[0071] Clause 16. The propulsion system of clause 1, wherein the first hybrid propulsion system and the second hybrid propulsion system are arranged in a parallel configuration.

[0072] Clause 17. A method of operating a propulsion system for an aircraft, the method comprising:

[0073] monitoring, by a control module, operation of a first engine and a second engine, wherein the first engine is part of a first hybrid propulsion system operably coupled to a first propeller, and the second engine is part of a second hybrid propulsion system operably coupled to a second propeller;

[0074] determining, by the control module, that the first engine or the second engine is not outputting an amount of torque required to maintain a desired phase of flight, wherein the first hybrid propulsion system includes a first motor coupled to the first engine by a first overrunning clutch, and the second hybrid propulsion system includes a second motor coupled to the second engine by a second overrunning clutch; and

[0075] In response to determining that the first engine or the second engine is not outputting the desired amount of torque, actuation of the cross-connect clutch from a disengaged position to an engaged position is instructed.

[0076] Clause 18. The method according to clause 17, further comprising:

[0077] When the engine torque of the first engine is greater than the motor torque of the first motor, the first overrunning clutch is engaged.

[0078] Clause 19. The method according to clause 18, further comprising:

[0079] When the engine torque of the second engine is greater than the motor torque of the second motor, the second overrunning clutch is engaged.

[0080] Article 20. An aircraft comprising:

[0081] cabin

[0082] a first thruster and a second thruster attached to and positioned on opposite sides of the nacelle;

[0083] a first hybrid propulsion system including a first motor coupled to the first engine via a first overrunning clutch, wherein the first hybrid propulsion system is operably coupled to drive a first propeller;

[0084] a second hybrid propulsion system including a second motor coupled to the second engine via a second overrunning clutch, wherein the second hybrid propulsion system is operably coupled to drive a second propeller; and

[0085] A cross-connect clutch is operably coupled to both the first hybrid propulsion system and the second hybrid propulsion system and is configured to actuate to an engaged position, wherein when the second engine is not outputting the torque required to maintain a desired flight phase of the aircraft, the cross-connect clutch is engaged, causing the first hybrid propulsion system to drive the second propeller, and wherein when the first engine is not outputting the torque required to maintain a desired flight phase of the aircraft, the cross-connect clutch is engaged, causing the second hybrid propulsion system to drive the first propeller.

[0086] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the gist of the present disclosure are intended to fall within the scope of the present disclosure. Such variations should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A propulsion system (10) for an aircraft (12), the propulsion system (10) comprising: A first propeller (20A) and a second propeller (20B); a first hybrid propulsion system (22A) comprising a first motor (38A) coupled to a first engine (36A) via a first overrunning clutch (40A), wherein the first hybrid propulsion system (22A) is operably coupled to drive the first propeller (20A); a second hybrid propulsion system (22B) comprising a second motor (38B) coupled to a second engine (36B) via a second overrunning clutch (40B), wherein the second hybrid propulsion system (22B) is operably coupled to drive the second propeller (20B); and A cross-connect clutch (26) is operably coupled to both the first hybrid propulsion system (22A) and the second hybrid propulsion system (22B) and is configured to be actuated to an engaged position.

2. The propulsion system (10) according to claim 1, wherein: The first overrunning clutch (40A) engages when the engine torque of the first engine (36A) is greater than the motor torque of the first motor (38A), and wherein the second overrunning clutch (40B) engages when the engine torque of the second engine (36B) is greater than the motor torque of the second motor (38B).

3. The propulsion system (10) according to any one of claims 1 to 2, wherein: The first motor (38A) and the second motor (38B) operate in a power mode of operation during a climb phase of flight of the aircraft (12) and in a regeneration mode during a cruise phase of flight of the aircraft (12).

4. The propulsion system (10) according to any one of claims 1 to 3, wherein: In all flight phases, the first engine (36A) and the first motor (38A) are coupled together via the first overrunning clutch (40A), and in all flight phases, the second engine (36B) and the second motor (38B) are coupled together via the second overrunning clutch (40B).

5. The propulsion system (10) of any one of claims 1 to 4, further comprising a control module (32) in electronic communication with the cross-connect clutch (26), wherein: The control module (32) instructs the cross-connect clutch (26) to actuate to the engaged position.

6. The propulsion system (10) according to any one of claims 1 to 5, wherein: The control module (32) executes instructions to: determining that the first engine (36A) or the second engine (36B) is not outputting an amount of torque required to maintain a desired phase of flight; as well as In response to determining that the first engine (36A) or the second engine (36B) is not outputting a desired amount of torque, the cross-connect clutch (26) is instructed to actuate from a disengaged position to the engaged position.

7. The propulsion system (10) according to any one of claims 1 to 6, further comprising a first battery pack (72A) electrically coupled to the first motor (38A) and a second battery pack (72B) electrically coupled to the second motor (38B), wherein: Both the first battery pack (72A) and the second battery pack (72B) include a plurality of individual batteries (80) that are recharged during the cruise phase of flight.

8. The propulsion system (10) according to any one of claims 1 to 7, wherein: The plurality of individual batteries (80) are connected to one another in a first arrangement during a climb phase of flight and in a second arrangement during a cruise phase of flight.

9. A method (200) of operating a propulsion system (10) for an aircraft (12), the method (200) comprising: monitoring, by a control module (32), operation of a first engine (36A) and a second engine (36B), wherein the first engine (36A) is part of a first hybrid propulsion system (22A) operably coupled to a first propeller (20A), and the second engine (36B) is part of a second hybrid propulsion system (22B) operably coupled to a second propeller (20B); determining, by the control module (32), that the first engine (36A) or the second engine (36B) is not outputting an amount of torque required to maintain a desired phase of flight, wherein the first hybrid propulsion system (22A) includes a first motor (38A) coupled to the first engine (36A) via a first overrunning clutch (40A), and the second hybrid propulsion system (22B) includes a second motor (38B) coupled to the second engine (36B) via a second overrunning clutch (40B); and In response to determining that the first engine (36A) or the second engine (36B) is not outputting a desired amount of torque, a cross-connect clutch (26) is instructed to be actuated from a disengaged position to an engaged position.

10. The method (200) of claim 9, further comprising: When the engine torque of the first engine (36A) is greater than the motor torque of the first motor (38A), the first overrunning clutch (40A) is engaged, and when the engine torque of the second engine (36B) is greater than the motor torque of the second motor (38B), the second overrunning clutch (40B) is engaged.

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