FLEXIBLE ARCHITECTURE FOR AN AEROSPACE HYBRID SYSTEM AND OPTIMIZED COMPONENTS THEREOF

A hybrid powertrain system includes an engine, an electric machine having a power shaft therein, and a clutch configured to releasably engage an output of the engine and the power shaft of the electric machine. The electric machine further includes an electrical output. The power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device. A controller is configured to control the engine, the electric machine, and the clutch to implement one or more power output modes.

BACKGROUND

There are varying types of aircraft that are propelled using different types of propulsion mechanisms, such as propellers, turbine or jet engines, rockets, or ramjets. Different types of propulsion mechanisms may be powered in different ways. For example, some propulsion mechanisms like a propeller may be powered by an internal combustion engine or an electric motor. As such, the combination of propulsion mechanisms and methods for providing power to those propulsion mechanisms are often designed specifically for particular aircraft, so that the propulsion mechanisms and methods for providing power to those propulsion mechanisms meet the specifications required to properly and safely propel an aircraft.

SUMMARY

In an embodiment, A hybrid powertrain system includes an engine, an electric machine having a power shaft therein, and a clutch configured to releasably engage an output of the engine and the power shaft of the electric machine. The electric machine further includes an electrical output. The power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device. A controller is configured to control the engine, the electric machine, and the clutch to implement one or more power output modes.

In an embodiment, a hybrid powertrain system includes an engine, a power shaft, and an electric machine having the power shaft therein. The electric machine further includes an electrical input/output. The hybrid powertrain system further includes a clutch configured to releasably engage an output of the engine to the power shaft. The electric machine is configured to receive power via the electrical input/output from an electric energy storage device to drive the power shaft. The electric machine is configured to output power via the electrical input/output upon rotation of the power shaft by the engine. The power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device.

In an embodiment, a hybrid powertrain system includes an engine and an electric machine having a power shaft therein. The electric machine further includes comprises an electrical input/output. The power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device. An output of the engine is configured to rotate the power shaft. The engine and the electric machine are configured to operate in a first mode in which the electric machine outputs first electrical power through the electrical input/output based on rotation of the power shaft, where the power shaft is rotated by the engine. The engine and the electric machine are configured to operate in a second mode in which both the engine and the electric machine drive the power shaft, where the electric machine drives the power shaft based on second electrical power received via the electrical input/output.

In an embodiment, a method includes controlling an engine and an electric machine having a power shaft therein to operate in a first mode. The first mode includes driving the power shaft by the engine, where an output of the engine is configured to rotate the power shaft. The first mode further includes outputting first electrical power from the electric machine through an electrical input/output of the electric machine based on the rotating of the power shaft by the engine. The method further includes controlling the engine and the electric machine to operate in a second mode comprising driving the power shaft by the engine and the electric machine simultaneously, where the electric machine drives the power shaft based on second electrical power received via the electrical input/output.

DETAILED DESCRIPTION

Aircraft typically have custom designed propulsion mechanisms and methods for powering those propulsion mechanisms. In this way, the propulsion mechanisms and power supplied to those propulsion mechanisms can be optimized to provide the amount of propulsion needed for a particular type and size of aircraft, while minimizing weight of the components in the aircraft. In other words, the propulsion mechanisms and power for those propulsion mechanisms are often optimized for a particular type and size of aircrafts such that components of one aircraft could not be easily used in a different types of aircraft drive architectures, such as direct drive aircraft, parallel drive aircraft, and serial drive aircraft.

Described herein are various embodiments for a flexible architecture for an aerospace hybrid system and optimized components thereof. A hybrid system may be or may include a system where fuel is burned in a piston, rotary, turbine, or other engine, and an output of the piston engine may be operatively connected to an electric generator for outputting electric power. The embodiments described herein may include flexible systems that can provide power for many different types of aircraft and propulsion mechanisms. Such systems may advantageously reduce the complexity of designing different types of aircraft, may reduce the costs of manufacturing such systems as less customization allows for economies of scale in mass producing the systems, and ultimately may reduce the complexity of aircraft that use the systems described herein.

The flexible architectures described herein may further be used to provide power to propulsion mechanisms in different ways, either in a same aircraft or in different aircraft. For example, a flexible architecture for providing power to propulsion mechanisms may be able to operate in multiple different modes to provide power to different types of propulsion mechanisms. A first aircraft may utilize one, some, or all of the multiple different modes in which the flexible architecture may operate. A second aircraft may utilize one, some, or all of the multiple different modes, and the modes utilized by the second aircraft may be different than those utilized by the first aircraft.

Therefore, different aircraft may take advantage of different modes of providing power to propulsion mechanisms provided by the flexible architectures described herein. While use of the flexible architectures may be customized in this way, the physical hardware of the flexible architectures may be adapted to use by different aircraft with minimal or no changes to the physical components of the flexible architectures described herein. Instead, the use of different modes in different aircraft may be accomplished largely based on how the components of the flexible architectures are controlled using a processor or controller. As such, computer readable instructions may therefore also be stored on a memory operably coupled to a processor or controller, such that when the instructions are executed by the processor or controller, a computing device that includes the processor or controller may control the various components of the flexible architectures described herein to utilize any possible mode of use desired for a particular implementation, aircraft, flight phase, etc.

Power generation and propulsion systems for aircraft may also utilize various cooling systems to ensure that the various components of an aircraft remain at safe temperatures for operation, as well as maintaining components within temperature ranges where they may operate more efficiently. Further described herein are advantageous cooling systems that leverage various aspects of the hybrid architecture described herein to efficiently cool components of a flexible architecture for providing power to propulsion mechanisms of an aircraft.

Aircraft that have hardware for providing different modes of power to its propulsion mechanisms, may have a variety of components for which it may be desirable to provide cooling. Thus, a single cooling system that efficiently moves air to the different components that enable different modes of power may cut down on weight of the aircraft, as well as power consumption of the cooling systems.FIGS.1-8and their accompanying description below specifically relate to example flexible architectures for providing power to propulsion systems of an aircraft, andFIGS.9-12and their accompanying description below relate to various embodiments of cooling systems for the example flexible architectures.

FIG.1Aillustrates an example flexible architecture101for an aerospace hybrid system in accordance with an illustrative embodiment. As discussed herein, the flexible architecture101may be efficiently used in a wide array of applications with a single hybrid generator system that can be applied in multiple ways depending on the aircraft requirements and phase of flight (e.g., used in different modes).

The flexible architecture101ofFIG.1Ais a hybrid generator that includes an engine105, a clutch115, a generator/motor121, and a power shaft111. As described further below, the flexible architecture101may be used to implement various different modes depending on requirements of a specific aircraft installation or a specific phase of flight as desired. The engine105may be a combustion engine, such as an internal combustion engine. The engine105may further specifically be one of a piston internal combustion engine, a rotary engine, or a turbine engine. Such engines may use standard gasoline, jet fuel (e.g., Jet A, Jet A-1, Jet B fuels), diesel fuel, biofuel substitutes, etc. In various embodiments, other types of engines may also be used, such as a smaller engine for drone implementations (e.g., a Rotax gasoline engine).

As described above, the engine105may be a piston combustion engine. A piston combustion engine may advantageously spin an output rotor or shaft at rotations per minute (RPMs) that may be more desirable for direct output to power a generator and/or a propulsion mechanisms (e.g., a propeller) than other engines. For example, a piston combustion engine may have an output on the order of thousands of RPMs. For example, a piston combustion engine may have an output anywhere from 2200 to 2500 RPM, which may be a desirable RPM for a propeller. In particular, a propeller may be designed to have a size that yields a desired tip speed of the propeller based on the RPM output of the piston combustion engine (e.g., of 2200 to 2500 RPM). Other types of engines, such as a turbine engine, may output rotational power on the order of tens of thousands of RPMs, much higher than a piston combustion engine. Another embodiment may drive the motor/generator at the higher RPM of a turbine engine to benefit the efficiency, power output, or other important factors. In some embodiments, a gear box could be added between the output of a high RPM engine and the other components ofFIG.1Ato step down the output RPM of the engine105. However, the addition of a gear box may also add weight to the system that is undesirable in some embodiments. A piston combustion engine may further be advantageous with respect to noise as compared to turbine engines. Turbine engines typically are louder than piston combustion engines, and the noise perceived by humans from a turbine engine is typically more offensive to a listener than the noise produced by a piston combustion engine. Quieter engines may also be more valuable in urban or more dense settings where reduced noise is desirable.

The engine105may output rotational power to the clutch115, which may be controlled to engage or disengage the power shaft111. In other words, the power shaft111may be engaged with the rotational output of the engine105by the clutch115, so that rotational force may be transferred between the engine105output and the power shaft111. When the clutch115disengages the output of the engine105and the power shaft111, the power shaft111may rotate independently of the output of the engine105. The clutch115may be physically located between the engine105and the generator/motor121, and may even contact the engine105and the generator/motor121on opposing sides in order to reduce the overall footprint of the flexible architecture. InFIG.1Aand further described herein and shown in other figures is the clutch115. However, in various embodiments, any mechanism that is capable of releasably decoupling the engine105and the power shaft111may be used additionally or alternatively to a clutch. For example, this decoupling may be based on absolute rotations per minute (RPM) or relative RPM between the engine105output and the power shaft111, such as in an overrunning clutch.

The generator/motor121may also be engaged or disengaged with the power shaft111. In other words, the generator/motor121may be controlled to switch off such that rotation of the power shaft111does not cause the generator/motor121to generate electrical power. Similarly, the generator/motor121may also be controlled to switch on such that the rotation of the power shaft causes the generator/motor121to generate electrical power. The generator/motor121is referred to as a generator/motor because it may function as either a generator or a motor. In various embodiments, the generator/motor121may be referred to as an electric machine, where an electric machine may be an electric generator, an electric motor, or both.

The flexible architecture further includes an electrical power input and output (I/O)125connected to the generator/motor121. As described further herein, the generator/motor121may generate electrical power based on rotation of the power shaft111that is output via the electrical power I/O125or may receive electrical power via the electrical power I/O125that may be used to drive the power shaft111. Wiring for the electrical power I/O125may include more than one wire. In various embodiments, the wiring for inputting electric power into the generator/motor121may be the same wiring that is used for outputting electric power out of the generator/motor121. In various other embodiments, first wiring may be used for input of electric power and different second wiring may be used for output of electric power (so that different wires are used for input and output). In various embodiments, the generator/motor121may also have wiring connected thereto that is used for control of the generator/motor121, to relay sensor or other data about the operation of the generator/motor121to a controller, etc.

The generator/motor121may also act as a driver for the power shaft111. Upon receiving electrical power via the electrical power I/O125from batteries or some other form of electrical energy storage elsewhere in the system, the generator/motor121may impart a rotational force on the power shaft111to drive the power shaft111. This may occur as long as the generator/motor121is controlled to be switched on to engage with the power shaft111. If the generator/motor121is controlled to be switched off such that it does not engage with the power shaft111, the power shaft111may not be rotated by the generator/motor121.

Electrical power output from the electrical power I/O125may be used to drive an electric motor for an electric propulsion mechanism (e.g., a propeller). Electrical power output from the electrical power I/O125may also be used to power and/or charge other devices on an aircraft or aerospace vehicle. For example, electrical power output from the electrical power I/O125may be used to charge one or more batteries. The electrical power output from the electrical power I/O125may also be used to power other devices or accessories on an aircraft or aerospace vehicle. Because the electrical power I/O125also has an input, the power shaft111may be driven by any electrical power received via the electrical power I/O125, such as power from one or more batteries. The power generated by the generator/motor121may be an alternating current (AC) power. That AC power may be converted by power electronics (e.g., a rectifier or inverter) into direct current (DC) power and output to a DC bus. That DC bus may be connected to batteries and/or an electric propulsion mechanism. In this way, the electric propulsion mechanism may be supplied with power via a DC bus. In various embodiments, a motor of the electric propulsion mechanism may use AC power, and the DC power from the DC bus may therefore be converted from DC power to AC power before it is used by the electric propulsion mechanism (e.g., by an inverter).

Any rotation of the power shaft111itself, whether driven by the engine105or the generator/motor121, may also be used to drive one or more propulsion mechanisms. For example, rotation of the power shaft111may be used to direct drive a propeller or may be used to power an electric motor that drives a propulsion mechanism. The rotation of the power shaft111may also drive a gearbox operably connected to another component, such as one or more propellers, one or more rotors, or other rotating devices for various uses on an aircraft.

An accessory pad130may also be coupled to the engine105, and may include a lower voltage direct current (DC) generator for electrical power that is separate from the generator/motor121and the electrical power I/O125, which may be configured for high voltage and high power I/O. In some embodiments, the generator/motor121may also have two different windings and the electrical power I/O125may have two different outputs (e.g., high voltage and low voltage). Accessory power may be associated with one of the electrical power I/O125outputs in addition to or instead of the accessory pad130output. The accessory pad130may be used to provide power to devices or accessories on an aircraft or aerospace vehicle that does not require high voltage or current outputs that may be output by the generator/motor121at the electrical power I/O125. A high voltage (HV) of an aircraft may be, for example, 400 volts (V) or 800 V, but may also be anywhere between 50 V to 1200 V. A low voltage (LV) of an aircraft may be 12 V, 14 V, 28 V, or any other voltage below 50 V.

FIG.1Billustrates an additional example flexible architecture150for an aerospace hybrid system in accordance with an illustrative embodiment. In particular, the flexible architecture150ofFIG.1Bincludes some components that may be the same as or similar to the components described above with respect toFIG.1A, including an engine155, a clutch175, a power shaft180, and/or a generator/motor185. The flexible architecture150further illustrates the output of the engine155in the form of a crankshaft160, which is rigidly connected to an output flange165. The output flange165is rigidly connected to one side of the clutch175with bolts170.

The clutch175may be configured to engage the power shaft180to translate rotational motion from the crankshaft160and the output flange165to the power shaft180. The clutch175may be further configured to disengage the power shaft180such that the power shaft180may rotate independently with respect the crankshaft160and the output flange165. In addition,FIG.1Bdemonstrates how the rotatable components of the flexible architecture150may be all be aligned along a single axis190. The rotatable components ofFIG.1Amay similarly be aligned along a single axis as shown inFIG.1B. In addition, the power shaft180may be a splined shaft that fits into an inner diameter opening of the clutch175and the generator/motor185. Other features than a spline may also be used, such as a taper. In any case, the generator/motor185and/or the clutch175may be configured to accommodate and connect to a spline, taper, or other feature on the power shaft180so that the components may properly engage with one another.

In various embodiments, the clutch175may be different types of clutches or other mechanisms capable of decoupling the power shaft180from the output of the engine155. For example, the clutch175may be a plate style clutch, and may be a dry or wet clutch. Such a plate style clutch may be engaged/disengaged or otherwise controlled mechanically, hydraulically, and/or electrically (e.g., by controllers205,220, and/or280ofFIGS.2A and2B). Plate style clutches may also have different numbers of plates, such as 3, 5, or 10 plates. In various embodiments, the clutch175or any other clutch described herein may be a one-way clutch, overrunning, or sprag clutch. The one-way or sprag clutch may be configured to disengage the output of the engine from the power shaft while the electric machine is rotating the power shaft faster than the output of the engine. In other words, if the engine155is outputting less power than the generator/motor185onto the power shaft180, the clutch175may automatically mechanically disengage the output of the engine155from the power shaft180, for example without any electrical control input used to accomplish said disengagement. Upon the engine155having a higher RPM or outputting more power than the generator/motor185, the one-way or sprag clutch may then engage so that power is applied from the output of the engine155to the power shaft180. Another type of clutch that may be used is a centrifugal clutch, where weights in the plates of a clutch trigger one or more levers progressively as the RPM increases to squeeze the plates of the centrifugal clutch and engage the plates to connect, for example, the output of the engine155and the power shaft180.

Advantageously, the generator/motor121ofFIG.1Aand/or the generator/motor185may be used as a starter for the engine105or the engine155, respectively. In other words, the generator/motor185may be used to turn the crankshaft160while the clutch175is engaged in order to start up the engine155. Such a system may be advantageous where, for example the generator/motor185may be powered by a battery or other electrical power source. The engine155, which may be a piston combustion engine as described herein, therefore may not require separate starter components, reducing the weight and complexity of the flexible architectures described herein.

FIG.2Aillustrates a block diagram representative of an aircraft control system200for use with a flexible architecture201for an aerospace hybrid system in accordance with an illustrative embodiment. The aircraft control system200may be used, for example, to implement one or more of the various modes discussed below in which the flexible architectures described herein may be used. The flexible architecture201may be the same as, similar as, or may have some or all of the components of the flexible architectures101and/or150ofFIGS.1A and/or1B. The aircraft control system200may include one or more processors or controllers205(hereinafter referred to as the controller205), memory210, a main aircraft controller220, an engine230, a generator/motor235, a clutch240, an electrical power I/O245, an accessory pad250, and one or more sensor(s)260. The connections inFIG.2Aindicate control signal related connections between components of the aircraft control system200. Other connections not shown inFIG.2Amay exist between different aspects of the aircraft and/or aircraft control system200for providing electrical power, such as a high voltage (HV) or low voltage (LV) power for an aircraft.

The memory210may be a computer readable media configured for instructions to be stored thereon. Such instructions may be computer executable code that is executed by the controller205to implement the various methods and systems described herein, including the various modes of using the flexible architectures herein and combinations of those modes. The computer code may be written such that the various methods of implementing different modes of the flexible architectures herein are automatically implemented based on various inputs that indicate, for example, a particular flight phase (e.g., landing, takeoff, cruising, etc.). In various embodiments the computer code may be written to implement the various modes herein based on input from a user or pilot of the aircraft or aerospace vehicle, or may be implemented based on a combination of user input and automatic implementation based on non-human inputs (e.g., from sensors on or off the aircraft, based on planned flight plans, etc.) The controller205may be powered by a power source on the aircraft or aerospace vehicle, such as the accessory pad130, one or more batteries, an output of the electrical power I/O125, a power bus of the aircraft powered by any power source, and/or any other power source available.

The controller205may also be in communication with each of the engine230, the generator/motor235, the clutch240, the electrical power I/O245, the accessory pad250, and/or the sensor(s)260. In this way, the components of flexible architectures may be controlled to implement various modes as described herein. In various embodiments, engine230, the generator/motor235, the clutch240, the electrical power I/O245, and the accessory pad250may be similar to or may be the similarly named components shown in and described above with respect toFIG.1A. The electrical power I/O245may also include pre-charge electronic components, for example, for protecting the electrical components of the flexible architectures, including a direct current (DC) bus, as described herein from excessive in rush current on startup. For example, if a high-voltage (HV) bus is at 400V and a new component is connected to the HV bus at 0 V, the instantaneous current rush may be extremely high and may be damaging to the HV bus and/or the component. As a result, the pre-charge electronic components may provide for slowly bringing up a component voltage before making a full connection to the HV bus or other power supply. In various embodiments, the HV bus may be a DC bus or an AC bus, or there may be multiple busses that are any of DC or AC busses. In instances where an AC bus is used, AC power may be output from a motor/generator to the AC bus directly. In instances where a DC bus is used, an inverter may be used to convert AC power from the motor/generator to DC power for output to the DC bus.

The sensor(s)260may include various sensors for monitoring the different components of the flexible architecture201. Such sensors may include temperature sensors, tachometers, fluid pressure sensors, voltage sensors, current sensors, state sensors to determine, for example, a current state of the clutch250, or any other type of sensor. For example, voltage and/or current sensors may be used to inform function and settings of a motor/generator, a state chosen for the clutch, or for adjusting any other component of a system. A state sensor could also indicate a specific mode the flexible architecture is being used in, and the system may receive inputs (e.g., from a pilot, from an automated flight controller), to change the system to a different state or mode for a certain phase of flight that may be upcoming. Other sensors may include a pitot tube for measuring aircraft airspeed, an altimeter for measuring aircraft altitude, and/or a global positioning system (GPS) or similar geographic location sensor for determining a location relative to the ground and/or known/mapped structures.

The components ofFIG.2Ainside the flexible architecture201dashed line may be associated with the flexible architecture as described herein, while the main aircraft controller220may be associated with the broader aircraft systems. In other words, the main aircraft controller220may control aspects of the aircraft other than the flexible architecture201, while the controller205controls aspects of the aircraft related to the flexible architecture201. The main aircraft controller220and the controller205may communicate with one another to coordinate providing power to the various propulsion mechanisms of the aircraft. For example, the main aircraft controller220may transmit signals to the controller205requesting particular power output levels for one or more particular propulsion mechanisms. The controller205may receive such control signals and determine how to adjust the flexible architecture201(e.g., what modes to enter and how to control the elements of the flexible architecture201) to output the desired power levels based on the control signals from the main aircraft controller220. In various embodiments, the main aircraft controller220may transmit signals that are related to controlling specific aspects of the flexible architecture201. In other words, the controller205may act as a relay to retransmit control signals from the main aircraft controller220to the components of the flexible architecture201, in addition to or instead of transmitting desired power output signals to the controller205from which the controller205determines how to control the individual components of the flexible architecture201.

In various embodiments, the main aircraft controller220may also transmit control signals related to future desired power outputs, future flight phase or flight plan information, etc. In this way, the controller205may receive and use information about the expected power demands of the aircraft to determine how to control the aspects of the flexible architecture201at both a present moment and in the future. For example, flight plan information may be used to determine when battery power should be used, when batteries should be charged, etc. In another example, if a big demand for power is expected, the controller205may ensure that the engine230is running at a desired RPM to begin delivering a desired level of power.

In various embodiments, the controller205may also be in communication with one or more batteries to monitor their charge levels, control when the batteries are charged or discharged, control when the batteries are used to power the generator/motor235, control when the batteries are used to directly power another aspect of the aircraft. However, in other embodiments, the main aircraft controller220may be in communication with batteries of the aircraft, and/or may relay information related to the batteries and control thereof to the controller205. Similarly, if the batteries of the aircraft are controlled with the main aircraft controller220rather than the controller205, the controller205may transmit control signals related to the batteries to the main aircraft controller so that the batteries may be controlled as needed or desired with respect to the functioning of the flexible architecture201.

In various embodiments, the electrical power I/O245may include two different outputs (e.g., a high voltage (HV) output and low voltage (LV) output) that are associated with two different windings of the generator/motor235. As such, two different voltages (e.g., HV and LV) may be output and controlled by the controller205and/or the main aircraft controller220. The electrical power I/O245may additionally or alternatively have voltage conversion components (e.g., a DC to DC converter) such that two or more different voltages may be output. In such an embodiment, two different outputs may be achieved without the use of two separate windings. The two different outputs may, for example, be output to different power busses on the aircraft, such as a HV bus and a LV bus. The two outputs of the electrical power I/O245may also be separately controlled by the controller205. As such, the outputs may be turned off (e.g., by letting the power shaft and rotor of the generator spin or freewheel with respect to the rest of the motor/generator by turning off field current of the motor/generator). In various embodiments, the power shaft may not actually be freewheeling within the generator/motor235. Instead, the power shaft may still rotate the rotor of the motor/generator235while the stator remains static, but the controller205may be used to control the output such that little or no electrical power is actually output by the motor/generator235. In various embodiments, the controller205may control the motor/generator235to output a desired level or threshold level of electrical power from the motor/generator235while letting the remaining power be output by the power shaft (e.g., to a propulsion mechanism). For example, the controller205may control the motor/generator235to generate anywhere from 0% to 100% of the power output from the engine to the power shaft into electric power. For example, the controller205may cause the motor/generator235to generate 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, or 100% of the power from the power shaft into electrical power.

In some embodiments, the accessory pad may not be controlled by the controller205and/or the main aircraft controller220. The accessory pad may simply always be on when the engine230is operating, or may be controlled separately (e.g., by a manual switch flipped by a user) to control when and how power is supplied to accessories on the aircraft.

In some embodiments, the controller205may be in communication with a wireless transceiver that may be on-board an aircraft or aerospace vehicle, so that the controller205may communicate with other computing devices not hard-wire connected to the system200. In this way, instructions or inputs for implementing the various modes for the flexible architectures described herein may also be received from a remote device computing device wirelessly. In other embodiments, the system200may only communicate with components on-board the aircraft.

FIG.2Billustrates a block diagram representative of a second aircraft control system275for use with a flexible architecture for an aerospace hybrid system in accordance with an illustrative embodiment. In the example ofFIG.2B, the system275does not have a separate main aircraft controller as inFIG.2A. Instead, the entire aircraft has a single main controller280that controls all aspects of the flexible architecture and the aircraft (including, e.g., propulsion mechanisms255of the aircraft).

The controller285may be in communication with one or more of the propulsion mechanism(s)255on the aircraft to control them. The controller285may also be in communication with one or more sensor(s)270on an aircraft or aerospace vehicle, which may be sensors of the aircraft and sensors of the flexible architecture. In particular, the sensor(s)260may also be embedded in any of the components ofFIGS.1A and/or1Bdescribed above, and therefore may be used to inform how the devices ofFIGS.1A and/or1Bare controlled and/or how the modes described herein are implemented as described herein.

In either ofFIG.2A or2B, the controller205, the controller285, and/or the main aircraft controller220may also be in communication with a cooling system configured to cool and/or heat any components of the flexible architecture, one or more batteries, or any other aspect of an aircraft. As such, a cooling system may also be controlled in concert with the other systems and methods described herein.

Described below are five specific modes that may be implemented using various embodiments of the flexible architecture described herein (including, e.g., the flexible architectures shown in and described with respect toFIGS.1A,1B,2A, and2B).

In a first mode, which may be referred to herein as a hybrid generator mode, a clutch (e.g., the clutch115ofFIG.1Aand/or the clutch175ofFIG.1B) may be controlled to engage an engine (e.g., the engine105ofFIG.1Aand/or the engine155ofFIG.1B) to a power shaft (e.g., the power shaft111ofFIG.1Aand/or the clutch output/power shaft180) that runs between the clutch to a generator/motor (e.g., the generator/motor121ofFIG.1Aand/or the generator motor185ofFIG.1B) such that the engine spins the power shaft within the generator/motor to generate electrical power to be supplied via an electrical power I/O (e.g., the electrical power I/O125ofFIG.1A) to other systems on an aircraft such as propulsion mechanisms/systems. For example, such propulsion mechanisms/systems may be powered using electric motors, and the electrical power output by the generator/motor in the first mode may be used to drive such propulsion mechanisms/systems. In short, in the first mode, the engine may be engaged with the power shaft using the clutch to drive the generator/motor and output electrical power from the generator/motor.

In a second mode, which may be referred to herein as a direct drive engine mode, a clutch (e.g., the clutch115ofFIG.1and/or the clutch175ofFIG.1B) may engage an engine (e.g., the engine105ofFIG.1Aand/or the engine155ofFIG.1B) output to a power shaft (e.g., the power shaft111ofFIG.1Aand/or the clutch output/power shaft180) that runs through a generator/motor (e.g., the generator/motor121ofFIG.1Aand/or the generator motor185ofFIG.1B) to provide mechanical power to a propulsion mechanism like a propeller on an aircraft. In such a mode, the field may be removed from the generator/motor (e.g., the generator/motor may be controlled to be off or disengaged) such that a power shaft and rotor of the generator/motor is spinning or freewheeling and an electrical power I/O (e.g., the electrical power I/O125ofFIG.1A) of the generator/motor is therefore disengaged and not outputting electrical power. In short, in the second mode, the engine may drive a power shaft to mechanically or otherwise power a propulsion mechanism, while the power shaft spins within the generator/motor without receiving or outputting electrical power at the electrical power I/O. As described herein, a controller may also be used to control how much power is generated and output by a generator/motor at its electrical power I/O, while allowing the rest of the power on the power shaft to be output to a propulsion device as mechanical power. A propulsion device may be, for example, any of rotor, propeller, fan, or other means of providing propulsion. As such, for example, if batteries on an aircraft are at full charge and electric motors on the aircraft are not be used, it may be desirable to only output mechanical power to a propulsion device and not convert any of the power on the power shaft to electric power. In other examples, it may be desirable to convert just a portion of the mechanical power from the power shaft into electric power. For example, the controller may cause the motor/generator to convert a certain percentage of power into electric power from the power shaft, or may monitor the power shaft to ensure that a minimum threshold of mechanical power is output to a propulsion mechanism (e.g., to maintain a certain airspeed or propulsion mechanism RPM) and then convert the rest of the power from the power shaft into electric power (e.g., to charge batteries or other energy storage devices on board the aircraft). As such, the various embodiments described herein may help prevent batteries on board the aircraft from being overcharged, may reduce the overall fuel consumed, etc., since the generator/motor may be controlled to output a certain amount of electrical power or no/little electrical power even while the power shaft and the rotor of the motor/generator is spinning. In various embodiments, this may be controlled by a controller by using the generator to control how much electrical energy is output, or may also be controlled by disengaging or partially disengaging the power shaft from the rotor of the motor/generator (or vice versa by disengaging the rotor from the power shaft).

In a third mode, which may be referred to herein as an augmented thrust mode, a clutch (e.g., the clutch115ofFIG.1and/or the clutch175ofFIG.1B) may engage an engine (e.g., the engine105ofFIG.1Aand/or the engine155ofFIG.1B) to a power shaft (e.g., the power shaft111ofFIG.1Aand/or the clutch output/power shaft180) that runs through a generator/motor (e.g., the generator/motor121ofFIG.1Aand/or the generator motor185ofFIG.1B) and the generator/motor is used as a motor to pull power in through an electrical power I/O (e.g., the electrical power I/O125ofFIG.1A) from an external source such as a battery pack. This provides a higher mechanical power output on the power shaft than either the engine or the generator/motor may be capable of delivering. In short, in the third mode, both the engine and the generator/motor are used to drive the power shaft simultaneously to send power to a propulsion mechanism.

In a fourth mode, which may be referred to herein as a direct drive generator/motor mode, a clutch (e.g., the clutch115ofFIG.1and/or the clutch175ofFIG.1B) may disengage an engine (e.g., the engine105ofFIG.1Aand/or the engine155ofFIG.1B) from a generator/motor (e.g., the generator/motor121ofFIG.1Aand/or the generator motor185ofFIG.1B) such that power can be fed to the generator/motor via an electrical power I/O (e.g., the electrical power I/O125ofFIG.1A) to drive the generator/motor as a motor and provide mechanical power to a power shaft (e.g., the power shaft111ofFIG.1Aand/or the clutch output/power shaft180). In short, in the fourth mode, the generator/motor alone may provide power to a propulsion mechanism based electrical power received at the electrical power I/O.

In a fifth mode, which may be referred to herein as a split engine power mode, a clutch (e.g., the clutch115ofFIG.1and/or the clutch175ofFIG.1B) may engage an engine (e.g., the engine105ofFIG.1Aand/or the engine155ofFIG.1B) to a generator/motor (e.g., the generator/motor121ofFIG.1Aand/or the generator motor185ofFIG.1B) such that the engine may cause the generator/motor to spin as a generator and provide both electrical power to other systems on the aircraft via an electrical power I/O (e.g., the electrical power I/O125ofFIG.1A) as well as providing mechanical power to a power shaft (e.g., the power shaft111ofFIG.1Aand/or the clutch output/power shaft180) to drive systems like a propeller. In short, in the fifth mode, the engine may be used to drive the power shaft and the generator/motor to output power via the electrical power I/O and the power shaft.

As described herein, any of these five modes (or variations thereof) may be used with the single flexible architecture described herein. In addition, certain modes and or combinations of modes may be beneficial for certain aircraft or aerospace vehicle types, certain propulsion mechanism types, certain flight phases of an aircraft or aerospace vehicle, etc.

For example, in a hybrid electric vertical takeoff and landing (VTOL) aircraft with electric motor driven propellers, the flexible architecture herein may be used solely as a source of electrical power. As such, the flexible architecture may drive the aircraft in the first mode (e.g., the hybrid generator mode) during any portion of a phase of flight in which power must be provided to a power bus of the aircraft or one or more motors of the aircraft.

In another example, in an aircraft with a single, large main pusher propeller (e.g., at the rear of a fuselage of an aircraft) and array of electric motors/propellers (e.g., on a wing of an aircraft) the flexible architecture may be used in the fifth mode (e.g., split engine power mode) during takeoff to supply power mechanically to the main pusher propeller and electrically to the wing-mounted motors.FIGS.3and4illustrate two examples of such an aircraft300and400with which a flexible architecture for an aerospace hybrid system may be used in accordance with an illustrative embodiment. For example, the aircraft300has a main pusher propeller305, and the aircraft400has a main pusher propeller405in the form of a ducted pusher fan. In both examples the fifth mode described herein may be used to supply power mechanically to the main pusher propellers305and405from a power shaft. Additionally, wing mounted electric motors/propellers310and410may be driven with electrical power from a motor/generator as described herein.

Alternatively, the flexible architecture described herein may be used to power configurations like those shown inFIGS.3and4in the third mode (e.g., augmented thrust mode) on takeoff by having a battery pack supply power to both the wing-mounted motors and to augment the engine power on the power shaft driving the main pusher propeller. In cruising flight, the aircraft may use the second mode (e.g., the direct drive engine mode) to just drive the main pusher propeller. In another example, during cruising flight, the aircraft may be equipped with a clutch between the power shaft and the pusher propeller, and the controller may cause the aircraft to operate in the first mode (e.g., hybrid generator mode) driving the wing mounted motors by disengaging the power shaft from the pusher propeller and outputting power from the generator/motor to the wing mounted motors. In another example (e.g., an emergency situation such where the engine failure), the pusher prop may be driven in the fourth mode (e.g., the direct drive generator/motor mode) using power input to the electrical power I/O such as from one or more batteries.

In another example, an aircraft may be a VTOL aircraft with a gyrocopter style main rotor that may be operated powered or unpowered, and may have forward propulsion motors and propellers mounted on wings. In an embodiment, the flexible architecture may be used entirely in the first mode (e.g., the hybrid generator mode) with electrical power supplied from the electrical power input/output (and the generator/motor) driving a motor coupled to the gyrocopter style main rotor and driving the wing-mounted motors using electrical power. In an embodiment, the aircraft may also be configured with a clutch between the power shaft and the gyrocopter style main rotor such that the flexible architecture may use the second mode (e.g., the direct drive engine mode) or the third mode (e.g., augmented thrust mode) to spin the gyrocopter style main rotor (e.g., to get the gyrocopter style rotor up to speed for takeoff). In such an example, the controller may then cause the flexible architecture to switch to the first mode (e.g., the hybrid generator mode) after the gyrocopter style rotor is up to speed (e.g., switch to the first mode for cruising flight). The fourth mode (e.g., the direct drive generator/motor mode) may again be used in the event of an engine failure to use electrical power to drive the power shaft (and therefore the gyrocopter style rotor) from a power source such as one or more batteries.

FIG.5illustrates another example aircraft500with which a flexible architecture for an aerospace hybrid system may be used in accordance with an illustrative embodiment. For example, the aircraft500may include multiple (e.g.,8) electric motors/propellers505on tilt wings, which may be powered using the first mode described herein (e.g., the hybrid generator mode), where an engine may be engaged with a power shaft using a clutch to drive a generator/motor and output electrical power from the generator/motor to the various electric motors/propellers505on the tilt wings.

Accordingly, described herein are advantageous flexible architectures for aircraft through which a variety of modes for supplying power to propulsion mechanisms may be achieved. While particular aircraft and propulsion mechanism configurations may not utilize each mode described herein that a flexible architecture is capable of, the flexible architectures may still be implemented in different aircraft to achieve different modes. Similarly, while an example of a flexible architecture with five different modes for powering propulsion mechanisms is described in detail herein, other flexible architectures with fewer, more, or different modes for powering propulsion mechanisms are also contemplated herein.

For example, a flexible architecture may not have a clutch as described herein and may still be able to implement various modes described herein where it is desirably to have the engine output coupled to the motor/generator and/or an output power shaft of the system. For example, in the first mode, the engine may rotate a power shaft to cause the generator to generate electricity. In the second mode, the engine may direct drive a mechanical propulsion component, for example, but the engine need not be disengaged from the motor/generator or power shaft because the motor/generator can be turned off or allow the power shaft and rotor of the motor/generator to freewheel within the motor/generator. In the third mode, the engine and motor/generator are used to drive the power shaft, so it would not be desirable to disengage the engine and the motor/generator using a clutch. In the fifth mode, the engine may rotate a power shaft to cause the generator to generate electricity and to cause the power shaft to mechanically power a propulsion mechanism. As such, the power shaft need not be disengaged from the engine output in an aircraft that utilizes any of the first, second, third and/or fifth modes as described above. As such, for an implementation that uses any combination of the first, second, third, and/or fifth modes (and not the fourth mode), a clutch may not be used as the system may have the output of the engine constantly connected to the power shaft in the motor/generator. Such an embodiment may be valuable because clutches may be heavy and/or unreliable.

FIG.6is a flow chart illustrating a first example method300for using a flexible architecture for an aerospace hybrid system in different flight phases of an aircraft with a main pusher propeller in accordance with an illustrative embodiment. In particular, the aircraft may be an aircraft with a single larger pusher propeller and an array of electric motors and corresponding smaller propellers on the wings. During a takeoff flight phase at602, the fifth mode described herein may be used to supply power mechanically to main pusher propeller and electrical power to wing-mounted motors. During a cruising flight phase at604, the second mode described herein may be used to supply power mechanically only to the main pusher propeller and not supply power to the smaller electric motors/propellers.

FIG.7is a flow chart illustrating a second example method400for using a flexible architecture for an aerospace hybrid system in different flight phases of an aircraft with a main pusher propeller in accordance with an illustrative embodiment. In particular, the aircraft may be an aircraft with a single larger pusher propeller and an array of electric motors and corresponding smaller propellers on the wings. During a takeoff flight phase at702, the third mode described herein called augmented thrust may be used to supply electrical power via a generator/motor to the main pusher propeller (drawing power from batteries) and providing power mechanically directly from the engine to the main pusher propeller. In addition, electrical power (generated by the generator/motor and/or directly from the batteries) may also be provided to the electric motors on the wings during takeoff. During a cruising flight phase at704, the second mode described herein may be used to supply power mechanically only to the main pusher propeller and not supply power to the smaller electric motors/propellers.

Referring back toFIG.1A, if the clutch115is engaged such that the engine105applies power to the power shaft111and the generator/motor121is not active or on, the power shaft111may freewheel within the generator/motor121(e.g., the second mode described above). Similarly, the power shaft180ofFIG.1Bmay freewheel within the generator/motor185in various embodiments. However, the engine105and/or the engine155may create torque pulses on the power shaft111and/or the power shaft180that can be dangerous to a generator, such as the generator/motor121and/or the generator/motor185when the clutch115and/or the clutch175is engaged with their respective power shafts111and/or180. In other words, large torque pulses on a shaft similar to those that may occur when certain types of engines fire (e.g., diesel piston combustion engines) may cause high angular accelerations that may cause fatigue or damage to components of the generator/motor121and/or the generator/motor185that are coupled to the power shafts111and/or180. As such, components to mitigate this torque may be used such as a flywheel or other heavy damping or spring coupling system to smooth out torque on the power shafts111and/or180.

FIG.8illustrates an example flexible architecture800for an aerospace hybrid system having a flywheel for absorbing oscillatory torque in accordance with an illustrative embodiment. In particular, the flexible architecture800includes similar or the same components to that shown in and described with respect toFIG.1B, but includes a flywheel195rigidly connected to the output flange165with the bolts170. The flywheel195is further connected rigidly to one side of the clutch175by bolts198. Rotational motion may therefore be translated from the engine155through the crankshaft160, the output flange165, and the flywheel195to the clutch175. The clutch175, may in turn engage or disengage with the power shaft180to selectively translate the rotational motion received from the flywheel195to the power shaft180. The flywheel195may further be, for example, a dual mass flywheel or spring coupling.

In other various embodiments, a flywheel may not be used. For example, further embodiments of damping systems and apparatuses are described herein that can damp torque on a power shaft (e.g., the power shaft111) but do not include a flywheel. Further, in various embodiments, a flywheel and other damping systems or components may be used in combination to damp or smooth out torque applied to a power shaft.

For example, the power shaft or rotor within the generator/motor itself may be rigidly coupled to a crankshaft of the generator/motor. In this way, the crankshaft and rotor together can damp the torque pulses on the power shaft or rotor, and may reduce tangential acceleration due to the torque pulses from an engine. In such embodiments, a clutch may be omitted. As such, a damping system would be internal to the generator/motor, and the footprint and weight of the damping systems may be less than a flywheel or other damping system that may be external to a generator/motor. In particular, the rigid coupling of the power shaft or rotor with the crankshaft may increase the inertia of the power shaft or rotor, such that the additional inertia helps prevent the power shaft from slowing down or otherwise rotating in a manner that would make it more susceptible to acceleration from torque pulses of an engine. In such embodiments, the power shaft or rotor and the crankshaft may function similarly to a flywheel.

In various embodiments, a generator/motor having a static inner portion and a spinning outer portion may be used. This may increase an inertia of the spinning portion and may allow the magnets in the generator/motor to spin and avoid being dislodged by torque spikes. In other words, the magnets may be already spinning in the outer portion and therefore may have a constant stabilizing radial force applied in addition to any tangential inertial force due to torque spike acceleration.

A torque damping system may also be configured as part of the power shaft or rotor that connects the output of the engine to the generator/motor. For example, a hub between the power shaft or rotor of the generator/motor may include a coupling that has torsional spring and/or damping properties. Torsional damping couplings may include an elastomeric component or spring (e.g., made from steel or another metal) that reduces potentially harmful torque impulses from being passed from an engine output to a power shaft or rotor of a generator. Torsional damping couplings may be similar to or may also be referred to as a resonance damping coupling. For example, such torsional damping couplings may reduce an overall system weight and size as opposed to systems that use a flywheel or other large damping system. One or more torsional damping couplings may be installed at any one or more of, within an engine, between an engine and clutch, in the clutch, between the clutch and the generator, and/or within the generator to achieve damping before the power shaft or rotor damages components of the generator itself.

Other ways of damping torque on a power shaft or rotor of a generator may also be used. For example, a magnetic field on a generator may be controlled to pulse it such that it acts upon the power shaft or rotor of the generator to cancel some or all of the torque pulses imparted on the power shaft or rotor by an engine. Such pulses on the field of the generator may be controlled based on a measurement of the torque pulses applied by the engine, and may result in the generator components not being damaged by the diesel engine. For example, the third mode described above where both an engine and a generator/motor apply power to a power shaft, pulses to the power shaft from the generator may both apply power to the power shaft and protect the components of the generator from being damaged. In the other modes described herein, pulses to the power shaft using the generator may be applied whenever the power shaft is being driven in whole in part by the engine. Thus, in order to properly protect the components of the generator in such a method, the pulses applied by the magnetic field of the generator to the power shaft or rotor may be configured to correlate to the torque pulses of the engine to properly counteract those torque pulses.

FIG.14illustrates an example flexible architecture1400for an aerospace hybrid system having a flywheel and a spring coupling for absorbing oscillatory torque in accordance with an illustrative embodiment. In particular, the flexible architecture1400includes similar or the same components to that shown in and described with respect toFIG.8, but includes a spring coupling199rigidly connected to the flywheel195and the power shaft180. The size, weight, etc. of the flywheel195, as well as characteristics of the spring coupling199, may be tuned according to the output of the engine155and the characteristics of one another, so that oscillatory torque may be reduces as much as desired and/or possible. For example, different engines may produce different amounts of oscillatory torque, so the various embodiments herein include flywheels and/or spring couplings having different characteristics to reduce vibration that is passed from the crankshaft160to the power shaft180. In various embodiments, the flexible architecture1400may not have a clutch, such that the crankshaft160and the power shaft180are always coupled to one another. In various embodiments, a flexible architecture similar to that ofFIG.14may also include a clutch so that the output of the engine155can ultimately be releasably decoupled from the power shaft180. In various embodiments, such a clutch may be connected between the spring coupling199and the power shaft180, or the power shaft may be split into multiple shafts with a clutch connecting the multiple shafts, or the clutch may be located anywhere else between the engine155and the generator/motor185so that the output of the engine155can be selectively decoupled from a portion of the power shaft180that passes through the generator/motor185. In various embodiments, a clutch may additionally or alternatively be positioned after the generator/motor185so that the power shaft180may be decoupled from a load (e.g., a propulsion mechanism of an aircraft).

Further described below are examples of how the flexible architectures described herein may be packaged and/or used in an actual aircraft. For example, certain aircraft may use electric motors to drive propulsion systems, and therefore must have sufficient on-board electrical energy or ways to generate such on-board electrical energy to drive those propulsion systems. In addition, regulations in a given jurisdiction may also require sufficient reserve energy to comply with operational regulations of an aircraft. The flexible architectures described herein may provide such electrical energy for propulsion systems and/or reserve energy such that they systems described herein may work with a variety of electric aircraft. For example, the embodiments herein provide for efficient conversion of jet fuel (or other liquid or gas fuel) to electricity, such that electric aircraft may be powered using widely available fuel sources.

FIG.9illustrates a perspective view900of an example flexible architecture for an aerospace hybrid system in accordance with an illustrative embodiment. This hybrid unit may be used as the core powerplant of a variety of aircraft types and implementations. The hybrid unit ofFIG.9is a tightly integrated powerplant that may include some, all, and/or additional elements shown in and described with respect toFIGS.1A,1B,2A,2B, and/orFIG.8.

In addition, the hybrid unit may include an integrated cooling system905that cools various aspects of the hybrid unit, heat exchangers related to the hybrid unit, or heat sinks such as finned attachments for any aspects of the hybrid unit. A power output910may be a power shaft (e.g., the power shaft110ofFIG.1A, the power shaft180ofFIG.1B or8) or connected to a power shaft, so that rotational power may be output from the hybrid unit to propulsion systems or other aspects of an aircraft. Electrical connectors915may also be used to output electrical power (or input electrical power) as described herein. The electrical connectors915may be, for example, an Amphenol Surlok Plus™ connector or equivalent, or may be any other type of suitable connector. In this way, a main bus, such as a direct current (DC) bus, of the hybrid unit may be connected to through the electrical connectors915(e.g., the electrical power input/output125ofFIG.1, the electrical I/O power245ofFIG.2A or2B). These or other connectors may also facilitate connection to and control of the components of the hybrid unit, such as using a controller area network (CAN) bus, a CAN 2.0 bus, and/or an SAE J1939 bus. Such communications busses may operate at different speeds, such as 250 kilobytes per second (kbps), 500 kbps, 1000 kbps, etc. In various embodiments, the electrical connectors915and/or other connectors may be customized for a given application, such as different types of aircraft and the communications and power systems that those aircraft use.

By virtue of the power output910and the electrical connectors915, the hybrid unit ofFIG.9may output either mechanical power via the power output910and/or electric power via the electrical connectors915and the DC bus in the hybrid unit (e.g., the electrical power input/output125ofFIG.1, the electrical I/O power245ofFIG.2A or2B). Similarly, electrical power may be received via the electrical connectors915to drive the power output910, just as mechanical power may be received via the power output910to generate electricity for output via the electrical connectors915. For example, if an aircraft includes one or more batteries, extra power from a battery may be received via the electrical connectors915to boost power applied to the power output910, such that the power output910is driven by both an engine and power from the batteries of an aircraft as described herein.

The hybrid unit ofFIG.9may further include connectors925for connecting the engine to a fuel source. The connectors925may be quick fuel connects, such as AN6 quick fuel connects. In this way, the engine may be supplied with fuel to power the power output910and/or to generate electricity to be output via the electrical connectors915. The hybrid unit ofFIG.9may additionally include mounting hardware920for mounting the hybrid unit to an aircraft. While the mounting hardware920is shown on the top of the hybrid unit inFIG.9, mounting hardware in other embodiments may additionally or alternatively be located on any of the top, bottom, sides, etc. of the hybrid unit, so that the hybrid unit may be mounted as desired to an aircraft.

FIG.10illustrates a top view1000of the example flexible architecture ofFIG.9in accordance with an illustrative embodiment.FIG.11illustrates a side view1100of the example flexible architecture ofFIG.9in accordance with an illustrative embodiment.

Accordingly, the hybrid units described herein may be used to power an electric or hybrid electric aircraft, and may offer better power than a battery pack alone would. For example, a hybrid unit as shown inFIGS.9-11may offer better energy density than batteries (e.g., 5 to 7 times better energy density). For example, the hybrid units described herein may have anywhere from 600-1200 or more Watt-hours per kilogram (Wh/kg) equivalent energy density. The hybrid units described herein may also advantageously have better fuel economy than other systems (e.g., 40% better fuel economy than a turbine engine), and may use readily available fuel such as Jet-A, diesel, kerosene, biofuel substitutes, or any other suitable or desired fuel. In other words, the hybrid units herein may include, in a compact package, an engine, a generator, an inverter, and thermal management using air cooling, such that aircraft in which the flexible architecture is installed may advantageously utilize these components as a powerplant. Outputs at various voltages, (e.g., 400 Volts (V), 800V, 1000V, 1200V, etc.) may be supplied from the hybrid architecture, as well as having connections for other accessory or system power (e.g., 28V). The flexible architectures described herein may also be quieter than other systems (e.g., quieter than turbine engine systems). For example, noise may be below 70 decibels (dB) at one hundred feet or less from the current systems.

The flexible architectures described herein may also be scalable. For example, in a larger aircraft, two or more of the flexible architectures described herein may be used. The flexible architectures may also be used in different aircrafts designed for different functions and purposes. For example, the flexible architectures described herein may be useful in urban air mobility (UAM) systems, such as electric vertical takeoff and landing (eVTOL) aircraft, electric short takeoff and landing (eSTOL) aircraft, electric conventional takeoff and landing (eCTOL) aircraft, etc. One example flexible architecture, such as the one shown inFIGS.9-11, may have the specifications shown in Table 1 below.

As shown above, a 185 kW hybrid unit may be provided. Accordingly, two hybrid units may be provided in a given aircraft to provide 370 kW of power.

FIG.12illustrates a perspective view1200of another example flexible architecture for an aerospace hybrid system in accordance with an illustrative embodiment. The flexible architecture ofFIG.12includes an engine1205and a generator, which is hidden or not visible because of other components such as the cooling ducts of the system. However, like the hybrid unit ofFIGS.9-11, a mechanical output power1210and electrical output power1220(which are also both optionally capable of receiving power as well) are provided.

As such, the various embodiments herein provide for a hybrid electric powerplants that may be incorporated into various different types of aircraft in the aerospace market. In doing so, aircraft manufacturers may not have to build their own systems that are made up of an engine, a generator, power electronics, cooling systems, and/or control systems to provide power to those aircraft. This may be advantageous, as a development process to create a powerplant system and certify it to aerospace standards may last 4+ years and may cost more than $10M.

As such, the hybrid powerplants or flexible architectures described herein may be design, manufactured, etc. separably from the design of the aircraft. A few aspects of the flexible architectures may be customized as desired by an aircraft manufacturer, but in a way that does not cause the total system to be redesigned or reconfigured. The embodiments herein therefore provide for an integrated unit that includes the engine, generator, power electronics, cooling systems, and/or control systems in one package to be installed on an aircraft. Combining these elements into a single standalone unit further advantageously allows for that unit to go through the Federal Aviation Administration (FAA) certification process as a system. Then, multiple aircraft manufacturers may use the certified system, removing that certification burden and development burden from the aircraft developer as well as adding efficiencies where multiple aircraft manufacturers will not have to seek certification of many different powerplant systems specifically designed for their aircraft.

By providing a combined unit having an engine, generator, power electronics, cooling systems, and/or control systems, the hybrid flexible architectures described herein may be optimized as a whole system rather than as individual components. entire system rather than optimization of the pieces. Additionally, such a hybrid unit may be used in multiple aircraft designs, whereas systems designed as part of an aircraft design process are configured such that it is difficult to reapply them elsewhere. Having a hybrid unit that may be applied in multiple market segments and aircraft designs with common power requirements leads to faster development of aircraft where a major component (e.g., the hybrid units or flexible architectures) of an aircraft is already certified and in production.

Hybrid electric systems for aviation have historically been designed from scratch for each application/aircraft. Such a process is inefficient and addressed by the embodiments herein. For example, some aircraft have unique powerplants designed specifically for the aircraft. Such a solution may include custom engine, generator, power electronics, control systems, cooling systems, battery pack, propulsion motors, and/or propellers. The embodiment herein provide for a compact hybrid system for an aircraft that may make up one half of two distinct halves within an aircraft power and propulsion system: upstream and downstream ends of a powertrain (such as a hybrid powertrain as described herein).

FIG.13illustrates example downstream1305,1310and upstream1315,1320components for propelling an aircraft1300in accordance with an illustrative embodiment. For example, downstream components1305,1310of an aircraft system may include motors, rotors/propellers, attitude control components, etc., that are more related to the specific design of an aircraft. Upstream components1315,1320of an aircraft that may be repeatable within different aircraft may include any of engines, generators, batteries, power distribution, fuel, generator noise abatement, etc.

Specifically, the upstream end of the powertrain may include hybrid powertrain elements responsible for producing electrical power. Such components may include the engine, generator, power electronics, control systems (for the upstream power generation components), cooling systems (for the upstream components), battery pack, and/or fuel. The downstream end of the powertrain may include hybrid powertrain elements responsible for turning the electrical power into thrust, attitude control, and/or active control of aerodynamics. These downstream components may further include electric motors, propellers, motor controllers, and/or control systems for the propulsion system.

As such, there may be common upstream powertrain needs across very different electric aircraft designs that are of similar sizes and total power requirements. However, the downstream powertrains may have little consistency from one aircraft to the next and therefore these components may not be standardized to work on many aircraft designs the way the upstream components can. Furthermore, the upstream elements that lend themselves to standardization may include the components that are linked to the power requirements but not the total energy requirements. In the case of the engine, generator, power electronics, cooling systems, and/or control systems, these elements of the upstream powertrain may be sized to fit a specific power requirement (kW or hp) of an aircraft. However, the quantity of fuel and the size of the battery pack may be driven by total energy requirements (kWh or hp hr) and these may vary from aircraft to aircraft. In such embodiments, the volume of fuel may be scaled by changing the size of the fuel tank to match the requirements of the aircraft design, and the capacity of the battery pack in kWh may be scaled by adjusting the number of parallel stacks of cells within a battery pack or by adding additional battery packs.

Therefore, provided herein are embodiments for supplying a hybrid powerplant that tightly integrates the engine, generator, power electronics, control systems (for the power generation system), and/or cooling systems in a weight-efficient and space efficient manner that can be certified as a standalone unit designed to provide propulsive power that is separable from the aircraft.

In addition, as described herein, a rotor inside the generator may be optimized to serve multiple purposes in the context of a hybrid powerplant. Conventional combustion engines may have a flywheel mass attached to the rotational shaft to enhance smoothness of operation. However, in the context of an aerospace system it may be unattractive to add extra mass. When an engine is coupled to a generator in a hybrid powerplant as described herein, the rotor in the generator may be designed to withstand any torque impulses from the engine and it may be designed to be the rotating mass that the engine utilizes for smoothness of operation.

Further, while auxiliary power units are known in the prior art, these systems may be designed for different purposes than as a primary source of propulsion power for an aircraft, and therefore may not have control systems capable of being certified to the standards required for use in propulsion. Additionally, such systems may be designed without the cooling systems, leaving that aspect to the airframe designer. As such, these systems are not certified to Part 33 (FAA regulations for aircraft powerplants). Also, these auxiliary power unit systems are designed to be lightweight auxiliary systems that are used intermittently rather than for highly efficient propulsion systems that are used in all phases of flight. Additionally, auxiliary power units may be designed to produce alternating current (AC) power, whereas hybrid electric powerplants as described herein may produce direct current (DC) power so that the hybrid electric powerplants may be coupled to a large propulsive battery pack, as battery packs provide and are charged using DC power.

Turbogenerators are a type of adapted auxiliary power units that have been proposed for hybrid power. Such systems lack cooling system integration that provides an airframe developer with a cooling system that is part of the hybrid powerplant. As such, airframe developers may be left to design their own cooling systems to accompany use of a turbogenerator. Using the embodiments herein, separate cooling systems for cooling the hybrid powerplants described herein may advantageously not need to be designed or developed for particular airframes, as such cooling systems are already included in the flexible architectures described herein.

As such, the flexible architectures and hybrid electric powerplants described herein advantageously provide an engine that converts liquid fuel (or gaseous fuel) into rotational mechanical power, a generator coupled to the engine that is configured to convert the rotational mechanical power to electricity, and/or power electronics coupled to the generator that are configured to convert the direct AC output of the generator to high voltage DC power. The flexible architectures and hybrid electric powerplants described herein further advantageously provide control systems that are configured to vary the power output of the engine to match the power demand on a main propulsive electrical bus of an aircraft to meet the demands of an aircraft for electric power.

Hybrid powerplant control systems, power electronics, generator, and/or engine designs described herein may further comply with regulatory requirements for the reliability of propulsive aerospace systems (e.g., failure should have a probability of less than 10−6or ten to the power of negative six). Flexible architectures and hybrid electric powerplants may further include a control interface that enables the flexible architecture or hybrid powerplant to communicate with a vehicle-level flight control systems to enable propulsive power commands to be provided from the vehicle-level flight control systems to the hybrid-powerplant control systems, and also advantageously provide for the hybrid-powerplant control systems to send status messages back to the vehicle-level flight control systems (e.g., feedback for use in controlling the flexible architecture or hybrid powerplant). Flexible architectures and hybrid electric powerplants may further include cooling systems that maintain the temperature range of the generator, power electronics, and/or engine over a full range of operating power output of the flexible architectures and hybrid electric powerplants described herein.

Various embodiments of flexible architectures or hybrid electric powerplants described herein may further include control systems that vary power output by varying engine torque and/or maintain rotations per minute (RPM) substantially constant over a significant range of power output. Such embodiments may provide for faster response of the flexible architectures or hybrid electric powerplants by eliminating throttle lag and a longer response time relating to system rotational inertia.

Various embodiments of flexible architectures or hybrid electric powerplants described herein may further include the option to provide a portion of the engine's power output as mechanical shaft power and a portion provided as DC electrical power. Various embodiments of flexible architectures or hybrid electric powerplants described herein may further include that the engine may be a piston engine, diesel piston engine, turbine engine, rotary engine, or other forms of combustion engine. Various embodiments of flexible architectures or hybrid electric powerplants described herein may further include examples where the rotor of the generator is designed to be a flywheel for the engine. Various embodiments of flexible architectures or hybrid electric powerplants described herein may further include a clutch between the engine and generator to enable operation of the generator as a motor that can be operated while the engine is shut down in some types of parallel hybrid installations as described herein.

At least some aspects of the present disclosure will now be described with reference to the following numbered clauses:1. A hybrid powertrain system comprising:an engine; andan electric machine having a power shaft therein, wherein the electric machine further comprises an electrical input/output, wherein:the power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device;an output of the engine is configured to rotate the power shaft;the engine and the electric machine are configured to operate in a first mode in which the electric machine is controlled to convert a variable amount of power from the power shaft's rotation by the engine into first electrical power while the power shaft is further configured to output any remaining mechanical power of the power shaft to the propulsion device; andthe engine and the electric machine are configured to operate in a second mode in which both the engine and the electric machine drive the power shaft, wherein the electric machine drives the power shaft based on second electrical power received via the electrical input/output.2. The hybrid powertrain system of clause 1, wherein the first electrical power is configured to be output to an electric propulsion device of the aircraft.3. The hybrid powertrain system of clause 2, wherein the electric propulsion device of the aircraft comprises at least one battery and at least one electric motor used for electric propulsion of the aircraft, wherein the at least one battery and the at least one electric motor are mounted to the aircraft.4. The hybrid powertrain system of clause 1, wherein in the first mode, the electric machine is controlled to convert no power from the power shaft into the first electric power.5. The hybrid powertrain system of clause 1, wherein in the first mode, the electric machine is controlled to convert all power from the power shaft into the first electric power.6. The hybrid powertrain system of clause 1, wherein in the first mode, the electric machine is controlled to convert somewhere between 0% and 100% of the power on the power shaft into the first electric power.7. The hybrid powertrain system of clause 5, further comprising a controller configured to cause the electric machine to vary a percentage of power converted from the power shaft to the first electric power by the electric machine.8. The hybrid powertrain system of clause 1, further comprising a controller configured to control the engine and the electric machine to output a first desired amount of the mechanical power to the propulsion mechanism and to output a second desired amount of the first electric power from the electric machine.9. The hybrid powertrain system of clause 1, further comprising a flywheel connected to at least one of the power shaft or the output of the engine.10. The hybrid powertrain system of clause 9, further comprising a spring coupling connected to the flywheel, wherein the spring coupling is configured to reduce vibration transmitted from the flywheel to the power shaft.11. The hybrid powertrain system of clause 1, wherein the second electrical power is received from one or more batteries of the aircraft during the second mode.12. The hybrid powertrain system of claim1, wherein the first electrical power is output to at least one of an electric motor or a battery.13. The hybrid powertrain system of clause 1, at least one of the power shaft or the output of the engine further supplies rotational power to a cooling system of the hybrid powertrain system.14. A method comprising:controlling an engine and an electric machine having a power shaft therein to operate in a first mode comprising:driving the power shaft by the engine, wherein an output of the engine is configured to rotate the power shaft; andoutputting first electrical power from the electric machine through an electrical input/output of the electric machine based on the rotating of the power shaft by the engine; andcontrolling the engine and the electric machine to operate in a second mode comprising driving the power shaft by the engine and the electric machine simultaneously, wherein the electric machine drives the power shaft based on second electrical power received via the electrical input/output.15. The method of clause 14, wherein the first electrical power is output to drive an electric propulsion motor of the aircraft or output to a propulsion battery of the aircraft, wherein the propulsion battery is used to power the electric propulsion motor.16. The method of clause 14, wherein the power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device.17. The method of clause 14, wherein a flywheel is connected to at least one of the power shaft or the output of the engine.18. The method of clause 17, wherein a spring coupling is connected to the flywheel, and wherein the spring coupling is configured to reduce vibration transmitted from the flywheel to the power shaft.19. The method of clause 14, wherein during the first mode, a first portion of rotational power applied to the power shaft by the engine is converted to electrical power by the electric machine and a second portion of the rotational power is supplied to the propulsion device via the power shaft.20. The method of clause 14, further comprising engaging a clutch during both the first mode and the second mode, wherein the clutch is configured to releasably engage the output of the engine to the power shaft.21. A hybrid powertrain system comprising:an engine;an electric machine having a power shaft therein; anda clutch configured to releasably engage an output of the engine and the power shaft of the electric machine, wherein:the electric machine further comprises an electrical output;the power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device; anda controller configured to control the engine, the electric machine, and the clutch to implement one or more power output modes.22. The hybrid powertrain system of clause 21, wherein the electric machine further comprises an electrical input, and wherein, in a mode of the one or more power output modes, the electric machine is configured to receive power via the electrical input from an electric energy storage device to drive the power shaft.23. The hybrid powertrain system of clause 22, wherein, during the mode, the clutch is disengaged such that the output of the engine does not rotate the power shaft.24. The hybrid powertrain system of clause 22, wherein, during the mode, the clutch is engaged such that the output of the engine rotates the power shaft.25. The hybrid powertrain system of clause 21, wherein the electric machine further comprises an electrical input, and wherein the one or more power output modes comprise at least:a first mode in which the electric machine outputs first electrical power through the electrical output based on rotation of the power shaft, wherein the power shaft is rotated by the engine while the clutch is engaged to couple the output of the engine and the power shaft; anda second mode in which both the engine and the electric machine drive the power shaft, wherein the electric machine drives the power shaft based on second electrical power received via the electrical input and the clutch is engaged to couple the output of the engine and the power shaft.26. The hybrid powertrain system of clause 21, wherein, in a mode of the one or more power output modes:the clutch is engaged and the engine rotates the power shaft;the electric machine is configured to receive power via the power shaft and convert a first portion of rotational power of the power shaft to electrical power that is output via the electrical output; anda second portion of the rotational power of the power shaft is applied to the propulsion device as the mechanical power.27. The hybrid powertrain system of clause 21, wherein, in a mode of the one or more power output modes:the clutch is engaged and the engine rotates the power shaft;the power shaft is configured to rotate within the electric machine without the electric machine converting rotational power of the power shaft to electrical power; andthe rotational power of the power shaft is applied to the propulsion device as the mechanical power.28. A hybrid powertrain system comprising:an engine;a power shaft;an electric machine having the power shaft therein, wherein the electric machine further comprises an electrical input/output; anda clutch configured to releasably engage an output of the engine to the power shaft,wherein:the electric machine is configured to receive power via the electrical input/output from an electric energy storage device to drive the power shaft;the electric machine is configured to output power via the electrical input/output upon rotation of the power shaft by the engine; andthe power shaft is configured to mechanically attach to and provide mechanical power to a propulsion device.29. The hybrid powertrain system of clause 28, wherein the electric machine is further configured to output the power via the electrical input/output to at least one of an electric motor or the electric energy storage device.30. The hybrid powertrain system of clause 28, wherein the electric machine cannot receive power to drive the electric machine and output power to at least one of the electric motor or the electric energy storage device at the same time.31. The hybrid powertrain system of clause 28, wherein the electric machine is controllable such that little or no electrical power is output by the electric machine despite rotation of the power shaft.32. The hybrid powertrain system of clause 31, wherein while the electric machine is controllable such that little or no electrical power is output by the electric machine, little or no power is input or output by the electric machine at the electrical input/output.33. The hybrid powertrain system of clause 28, wherein while the electric machine outputs power via the electrical input/output upon the rotation of the power shaft by the engine, the electric machine is configured to convert only a portion of the rotational energy provided by the power shaft into electrical power that is output at the electrical input/output.34. The hybrid powertrain system of clause 28, wherein the clutch is configured to disengage the output of the engine from the power shaft while the electric machine drives the power shaft with electrical power received via the electrical input/output.35. The hybrid powertrain system of clause 28, wherein the power shaft is configured to be driven by the electric machine and the engine simultaneously while the clutch is engaged to connect the output of the engine to the power shaft.36. The hybrid powertrain system of clause 28, wherein the clutch comprises a one-way clutch configured to disengage the output of the engine from the power shaft while the electric machine is rotating the power shaft faster than the output of the engine.37. The hybrid powertrain system of clause 28, wherein the one-way clutch comprises a sprag clutch.

FIG.15is a diagrammatic view of an example of a computing environment that includes a general-purpose computing system environment100, such as a desktop computer, laptop, smartphone, tablet, or any other such device having the ability to execute instructions, such as those stored within a non-transient, computer-readable medium. Various computing devices as disclosed herein (e.g., the processor(s)/controller(s)205, the main aircraft controller220, the processor(s)/controller(s)280, or any other computing device in communication with those controllers that may be part of other components of an aircraft or control system of an aircraft—whether on board the aircraft or remote from the aircraft) may be similar to the computing system100or may include some components of the computing system100. Furthermore, while described and illustrated in the context of a single computing system100, those skilled in the art will also appreciate that the various tasks described hereinafter may be practiced in a distributed environment having multiple computing systems100linked via a local or wide-area network in which the executable instructions may be associated with and/or executed by one or more of multiple computing systems100.

In its most basic configuration, computing system environment100typically includes at least one processing unit102and at least one memory104, which may be linked via a bus106. Depending on the exact configuration and type of computing system environment, memory104may be volatile (such as RAM110), non-volatile (such as ROM108, flash memory, etc.) or some combination of the two. Computing system environment100may have additional features and/or functionality. For example, computing system environment100may also include additional storage (removable and/or non-removable) including, but not limited to, magnetic or optical disks, tape drives and/or flash drives. Such additional memory devices may be made accessible to the computing system environment100by means of, for example, a hard disk drive interface112, a magnetic disk drive interface114, and/or an optical disk drive interface116. As will be understood, these devices, which would be linked to the system bus306, respectively, allow for reading from and writing to a hard disk118, reading from or writing to a removable magnetic disk120, and/or for reading from or writing to a removable optical disk122, such as a CD/DVD ROM or other optical media. The drive interfaces and their associated computer-readable media allow for the nonvolatile storage of computer readable instructions, data structures, program modules and other data for the computing system environment100. Those skilled in the art will further appreciate that other types of computer readable media that can store data may be used for this same purpose. Examples of such media devices include, but are not limited to, magnetic cassettes, flash memory cards, digital videodisks, Bernoulli cartridges, random access memories, nano-drives, memory sticks, other read/write and/or read-only memories and/or any other method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Any such computer storage media may be part of computing system environment100.

A number of program modules may be stored in one or more of the memory/media devices. For example, a basic input/output system (BIOS)124, containing the basic routines that help to transfer information between elements within the computing system environment100, such as during start-up, may be stored in ROM108. Similarly, RAM110, hard drive118, and/or peripheral memory devices may be used to store computer executable instructions comprising an operating system126, one or more applications programs128(which may include the functionality disclosed herein, for example), other program modules130, and/or program data122. Still further, computer-executable instructions may be downloaded to the computing environment100as needed, for example, via a network connection.

An end-user may enter commands and information into the computing system environment100through input devices such as a keyboard134and/or a pointing device136. While not illustrated, other input devices may include a microphone, a joystick, a game pad, a scanner, etc. These and other input devices would typically be connected to the processing unit102by means of a peripheral interface138which, in turn, would be coupled to bus106. Input devices may be directly or indirectly connected to processor102via interfaces such as, for example, a parallel port, game port, firewire, or a universal serial bus (USB). To view information from the computing system environment100, a monitor140or other type of display device may also be connected to bus106via an interface, such as via video adapter132. In addition to the monitor140, the computing system environment100may also include other peripheral output devices, not shown, such as speakers and printers.

The computing system environment100may also utilize logical connections to one or more computing system environments. Communications between the computing system environment100and the remote computing system environment may be exchanged via a further processing device, such a network router152, that is responsible for network routing. Communications with the network router152may be performed via a network interface component154. Thus, within such a networked environment, e.g., the Internet, World Wide Web, LAN, or other like type of wired or wireless network, it will be appreciated that program modules depicted relative to the computing system environment100, or portions thereof, may be stored in the memory storage device(s) of the computing system environment100.

The computing system environment100may also include localization hardware186for determining a location of the computing system environment100. In some instances, the localization hardware156may include, for example only, a GPS antenna, an RFID chip or reader, a WiFi antenna, or other computing hardware that may be used to capture or transmit signals that may be used to determine the location of the computing system environment100.

While this disclosure has described certain embodiments, it will be understood that the claims are not intended to be limited to these embodiments except as explicitly recited in the claims. On the contrary, the instant disclosure is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the disclosure. Furthermore, in the detailed description of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be obvious to one of ordinary skill in the art that systems and methods consistent with this disclosure may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure various aspects of the present disclosure.

Some portions of the detailed descriptions of this disclosure have been presented in terms of procedures, logic blocks, processing, and other symbolic representations of operations on data bits within a computer or digital system memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, logic block, process, etc., is herein, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these physical manipulations take the form of electrical or magnetic data capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system or similar electronic computing device. For reasons of convenience, and with reference to common usage, such data is referred to as bits, values, elements, symbols, characters, terms, numbers, or the like, with reference to various presently disclosed embodiments.

It should be borne in mind, however, that these terms are to be interpreted as referencing physical manipulations and quantities and are merely convenient labels that should be interpreted further in view of terms commonly used in the art. Unless specifically stated otherwise, as apparent from the discussion herein, it is understood that throughout discussions of the present embodiment, discussions utilizing terms such as “determining” or “outputting” or “transmitting” or “recording” or “locating” or “storing” or “displaying” or “receiving” or “recognizing” or “utilizing” or “generating” or “providing” or “accessing” or “checking” or “notifying” or “delivering” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data. The data is represented as physical (electronic) quantities within the computer system's registers and memories and is transformed into other data similarly represented as physical quantities within the computer system memories or registers, or other such information storage, transmission, or display devices as described herein or otherwise understood to one of ordinary skill in the art.

In an illustrative embodiment, any of the operations described herein may be implemented at least in part as computer-readable instructions stored on a computer-readable medium or memory. Upon execution of the computer-readable instructions by a processor, the computer-readable instructions may cause a computing device to perform the operations.

The foregoing description of illustrative embodiments has been presented for purposes of illustration and of description. It is not intended to be exhaustive or limiting with respect to the precise form disclosed, and modifications and variations are possible in light of the above teachings or from practice of the disclosed embodiments. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.