Oil circulation system for hybrid electric engine

A hybrid electric propulsion system including: a gas turbine engine comprising a low speed spool, a high speed spool, and a combustor; a lubrication circuit comprising a bearing compartment, a supply pump, and a scavenger pump; an electric motor configured to augment rotational power of the low speed spool or the high speed spool; and a controller operable to: control the electric motor based upon a pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment and to drive rotation of the low speed spool and/or the high speed spool via the electric motor responsive to a thrust command while fuel flow to the combustor is inhibited.

BACKGROUND

The subject matter disclosed herein relates generally to hybrid electric engines and, more particularly, to a method and an apparatus for providing circulating oil in a hybrid electric engine and/or an engine with electric power assist.

In a hybrid electric system where it is possible to transfer power from the low spool to the high spool to slow down the fan or improve compressor stability, reduction of the low spool speed too far can create an oil containment problem. As such, providing the required amount of oil to the bearings of an engine may be a limiting factor in how much power can be transferred while still maintaining sufficient lubrication.

Accordingly, it is desirable to provide a hybrid electric engine and/or an engine with electric power assist with an oil circulation system that prevents oil containment issues of the oil circulation system.

BRIEF DESCRIPTION

Disclosed is a hybrid electric propulsion system including: a gas turbine engine comprising a low speed spool, a high speed spool, and a combustor; a lubrication circuit comprising a bearing compartment, a supply pump, and a scavenger pump; an electric motor configured to augment rotational power of the low speed spool or the high speed spool; and a controller operable to: control the electric motor based upon a pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment and to drive rotation of the low speed spool and/or the high speed spool via the electric motor responsive to a thrust command while fuel flow to the combustor is inhibited.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the hybrid electric propulsion system includes a power source operably coupled to the electric motor.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the power source is at least one of the following: a battery; a super capacitor; and an ultra capacitor.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller is a full authority digital engine control (FADEC) that has full authority over the power source, and the electric motor.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the supply pump and the scavenger pump are mechanically coupled to the low speed spool and/or the high speed spool.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the supply pump and the scavenger pump are mechanically decoupled from the low speed spool and high speed spool.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the hybrid electric propulsion system includes a supplemental electric motor configured to drive the supply pump and the scavenger pump, the electric motor and the supplemental electric motor being independently operated by the controller.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the supplemental electric motor is operably coupled to the power source.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the bearing further comprises a non-contact seal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the bearing compartment is sealed with a contact seal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the bearing compartment is sealed with a non-contact seal.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the lubrication circuit further includes an electrically actuatable valve controlled by the controller.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the lubrication circuit further includes a pressure sensor for determining a pressure in the bearing compartment.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the lubrication circuit further includes a pressure sensor for determining a pressure outside of the bearing compartment.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller is a full authority digital engine control (FADEC).

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the electric motor is connected to an engine accessory gearbox that is operably coupled to the high speed spool.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the lubrication circuit further includes an electrically actuatable valve controlled by the controller.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the lubrication circuit further includes a pressure sensor for determining a pressure in the bearing compartment.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller is a full authority digital engine control (FADEC).

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the power source is at least one of the following: a battery; a super capacitor; and an ultra capacitor.

Also disclosed is a method for controlling an oil pressure in a bearing compartment of a gas turbine engine, the method including: providing power assist to a high speed spool and/or a low speed spool of the gas turbine engine via an electric motor operably coupled to the high speed spool and/or the low speed spool; maintaining a pressure in the bearing compartment or a scavenger line of a lubrication circuit of the gas turbine engine at a desired pressure, the gas turbine engine comprising a bearing compartment, a supply pump, and a scavenger pump; and controlling the electric motor based upon a pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment and via a controller to drive rotation of the low speed spool and/or the high speed spool via the electric motor responsive to a thrust command while fuel flow to a combustor of the gas turbine engine is inhibited.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the supply pump and the scavenger pump are mechanically decoupled from the low speed spool and high speed spool and a supplemental electric motor drives the supply pump and the scavenger pump, the electric motor and the supplemental electric motor being independently operated by the controller.

Also disclosed is a hybrid electric propulsion system, including: a gas turbine engine comprising a low speed spool, a high speed spool, and a combustor; a lubrication circuit comprising a bearing compartment, a supply pump, and a scavenger pump; an electric motor configured to augment rotational power of the low speed spool or the high speed spool; a supplemental motor operably coupled to the supply pump or the scavenger pump; and a controller operable to: control the supplemental motor based upon an operational condition of the hybrid electric propulsion system.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the operable operational condition of the hybrid electric propulsion system is a pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the operable operational condition of the hybrid electric propulsion system is a rotational speed of the low speed spool and/or the high speed spool.

In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the gas turbine engine is a geared turbofan gas turbine engine.

DETAILED DESCRIPTION

The core airflow is compressed by the low pressure compressor44then the high pressure compressor52, mixed and burned with fuel in the combustor56, then expanded over the high pressure turbine54and low pressure turbine46. In some embodiments, stator vanes45in the low pressure compressor44and stator vanes55in the high pressure compressor52may be adjustable during operation of the gas turbine engine20to support various operating conditions. In other embodiments, the stator vanes45,55may be held in a fixed position. The turbines46,54rotationally drive the respective low speed spool30and high speed spool32in response to the expansion. It will be appreciated that each of the positions of the fan section22, compressor section24, combustor section26, turbine section28, and fan drive gear system48may be varied. For example, gear system48may be located aft of combustor section26or even aft of turbine section28, and fan section22may be positioned forward or aft of the location of gear system48.

While the example ofFIG.1illustrates one example of the gas turbine engine20, it will be understood that any number of spools, inclusion or omission of the gear system48, and/or other elements and subsystems are contemplated. Further, rotor systems described herein can be used in a variety of applications and need not be limited to gas turbine engines for aircraft applications. For example, rotor systems can be included in power generation systems, which may be ground-based as a fixed position or mobile system, and other such applications.

FIG.2illustrates a hybrid electric propulsion system100(also referred to as hybrid gas turbine engine or hybrid electric engine100) including a gas turbine engine120operably coupled to an electrical power system210as part of a hybrid electric aircraft. One or more mechanical power transmissions150(e.g.,150A,150B) can be operably coupled between the gas turbine engine120and the electrical power system210. The gas turbine engine120can be an embodiment of the gas turbine engine20ofFIG.1and includes one or more spools, such as low speed spool30and high speed spool32, each with at least one compressor section and at least one turbine section operably coupled to a shaft (e.g., low pressure compressor44and low pressure turbine46coupled to inner shaft40and high pressure compressor52and high pressure turbine54coupled to outer shaft50as depicted inFIG.1). The electrical power system210can include a first electric motor212A configured to augment rotational power of the low speed spool30and a second electric motor212B configured to augment rotational power of the high speed spool32. Although two electric motors212A,212B are depicted inFIG.2, it will be understood that there may be only a single electric motor (e.g., only electric motor212B for rotation of the high speed spool as discussed below) or additional electric motors (not depicted). The electrical power system210can also include a first electric generator213A configured to convert rotational power of the low speed spool30to electric power and a second electric generator213B configured to convert rotational power of the high speed spool32to electric power. Although two electric generators213A,213B are depicted inFIG.2, it will be understood that there may be only a single electric generator (e.g., only electric generator213A) or additional electric generators (not depicted). In some embodiments, one or more of the electric motors212A,212B can be configured as a motor or a generator (e.g., a motor generator or equivalent electric machine capable of ether providing a rotational force from electrical energy or generating electrical energy from mechanical energy) depending upon an operational mode or system configuration, and thus one or more of the electric generators213A,213B may be omitted.

In the example ofFIG.2, the mechanical power transmission150A includes a gearbox operably coupled between the inner shaft40and a combination of the first electric motor212A and first electric generator213A. The mechanical power transmission150B can include a gearbox operably coupled between the outer shaft50and a combination of the second electric motor212B and second electric generator213B. In embodiments where the electric motors212A,212B are configurable between a motor and generator mode of operation, the mechanical power transmission150A,150B can include a clutch or other interfacing element(s).

The electrical power system210can also include motor drive electronics214A,214B operable to condition current to the electric motors212A,212B (e.g., DC-to-AC converters). The electrical power system210can also include rectifier electronics215A,215B operable to condition current from the electric generators213A,213B (e.g., AC-to-DC converters). The motor drive electronics214A,214B and rectifier electronics215A,215B can interface with an energy storage management system216that further interfaces with an energy storage system218. The energy storage management system216can be a bi-directional DC-DC converter that regulates voltages between energy storage system218and electronics214A,214B,215A,215B. The energy storage system218can include one or more energy storage devices, such as a battery, a super capacitor, an ultra capacitor, and the like. The energy storage management system216can facilitate various power transfers within the hybrid electric propulsion system or hybrid electric engine100. For example, power from the first electric generator213A can be transferred211to the second electric motor212B as a low speed spool30to high speed spool32power transfer. Other examples of power transfers may include a power transfer from the second electric generator213B to the first electric motor212A as a high speed spool32to low speed spool30power transfer.

A power conditioning unit220and/or other components can be powered by the energy storage system218. The power conditioning unit220can distribute electric power to support actuation and other functions of the gas turbine engine120. For example, the power conditioning unit220can power an integrated fuel control unit222to control fuel flow to the gas turbine engine120. The power conditioning unit220can power a supply pump or scavenger pump of a lubrication system288. The power conditioning unit220can power a plurality of actuators224, such as one or more of a low pressure compressor bleed valve actuator226, a low pressure compressor vane actuator228, a high pressure compressor vane actuator230, an active clearance control actuator232, and other such effectors. In some embodiments, the low pressure compressor vane actuator228and/or the high pressure compressor vane actuator230can be omitted where active control of stator vanes45,55ofFIG.1is not needed. Collectively, any effectors that can change a state of the gas turbine engine120and/or the electrical power system210may be referred to as hybrid electric system control effectors240. Examples of the hybrid electric system control effectors240can include the electric motors212A,212B, electric generators213A,213B, integrated fuel control unit222, actuators224and/or other elements (not depicted).

In one non-limiting embodiment and through electrical boost provided to the high speed spool32and/or the low speed spool30variable vane actuators of the high speed spool32and/or the low speed spool30may be reduced and/or eliminated as the need for variable vanes may be reduced or eliminated.

FIG.3is a schematic diagram of control signal paths250of the hybrid electric propulsion system or hybrid electric engine100ofFIG.2and is described with continued reference toFIGS.1and2. A controller256can interface with the motor drive electronics214A,214B, rectifier electronics215A,215B, energy storage management system216, integrated fuel control unit222, actuators224, and/or other components (not depicted) of the hybrid electric propulsion system or hybrid electric engine100. In embodiments, the controller256can control and monitor for fault conditions of the gas turbine engine120and/or the electrical power system210. For example, the controller256can be integrally formed or otherwise in communication with a full authority digital engine control (FADEC) of the gas turbine engine120. In embodiments, the controller256can include a processing system260, a memory system262, and an input/output interface264. The controller256can also include various operational controls, such as a power transfer control266that controls the hybrid electric system control effectors240as further described herein.

The processing system260can include any type or combination of central processing unit (CPU), including one or more of: a microprocessor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like. The memory system262can store data and instructions that are executed by the processing system260. In embodiments, the memory system262may include random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic, or any other computer readable medium onto which is stored data and algorithms in a non-transitory form. The input/output interface264is configured to collect sensor data from the one or more system sensors and interface with various components and subsystems, such as components of the motor drive electronics214A,214B, rectifier electronics215A,215B, energy storage management system216, integrated fuel control unit222, actuators224, and/or other components (not depicted) of the hybrid electric propulsion system or hybrid electric engine100. The controller256provides a means for controlling the hybrid electric system control effectors240based on a power transfer control266that is dynamically updated during operation of the hybrid electric propulsion system or hybrid electric engine100. The means for controlling the hybrid electric system control effectors240can be otherwise subdivided, distributed, or combined with other control elements.

The power transfer control266can apply control laws and access/update models to determine how to control and transfer power to and from the hybrid electric system control effectors240. For example, sensed and/or derived parameters related to speed, flow rate, pressure ratios, temperature, thrust, and the like can be used to establish operational schedules and transition limits to maintain efficient operation of the gas turbine engine120.

Referring now toFIG.4, a hybrid electric propulsion system100(also referred to as hybrid gas turbine engine or hybrid electric engine100) including a gas turbine engine120operably coupled to the electrical power system210as part of a hybrid electric aircraft in accordance with one non-limiting embodiment of the present disclosure is illustrated. In this embodiment, the engine120has a power source280such as a battery, a super capacitor, an ultra capacitor or an equivalent thereof, which supplies power to a motor282, which is connected to an engine accessory gearbox284that is operably coupled to the high speed spool32such that the motor282, when operated will provide power assist to the high speed spool32via the accessory gearbox284. In other words, the accessory gearbox will have at least one component (e.g., a gear train or other equivalent device) operably coupled to the high speed spool32and the motor282such that operation of the motor282will rotate the component which in turn will rotate the high speed spool32.

In one non-limiting embodiment, motor282may be motor212B illustrated inFIG.2, which is configured to provide power assist to the high speed spool32.

In an alternative embodiment, motor282may be operatively coupled to the low speed spool30via accessory gearbox284in order to provide additional thrust to the engine20. Such as motor212A illustrated inFIG.2. In addition and as previously mentioned, power source280may be the first electrical generator213A and/or the second electric generator213B or any other equivalent device for providing power to motor282.

The system may be referred to a power assist system286that limits or avoids pilot or aircraft control intervention during operation and the full authority digital engine control (FADEC) controls the power source and the engine. As such, the motor282provides power to augment the high speed spool32and/or the low speed spool30responsive to a thrust command to the engine while fuel flow to the combustor is inhibited. During such a thrust command, lubrication must still be provided to a lubrication system of the engine20.

The power assist to the high speed spool32via the motor282will allow the motor to also drive a supply pump or scavenger pump mechanically coupled to the spools (e.g., high and/or low) of the engine. This allows for oil supply and oil containment in the lubrication system by electrically driving spools as opposed to driving the engine via fuel which can create seal pressures that need to be compensated for in the bearing compartments of the lubrication system. For example, in anon-hybrid engine without electric assist, oil pumps of a lubrication system are mechanically coupled to at least one of the spools of the engine and the driving of the spools via combustion of fuel will in turn drive the oil pumps of the lubrication system. However and during some operational conditions, it is desirable to provide lubricant to a bearing cavity while also accounting for pressure differentials between the inside and the outside of the bearing cavity that must be accounted for in the lubrication system so that the oil is retained in the bearing compartments or other components where it is desired.

In addition and in combination with the power assist system286, the hybrid electric engine100includes a lubrication system288that is configured to operate in conjunction with the power assist system286.

Referring now toFIG.5, a schematic illustration of the lubrication system288in accordance with various embodiments of the present disclosure is illustrated. As illustrated, a fluid circuit290exits. The fluid circuit290includes at least a supply pump292, an oil tank or reservoir294, at least one bearing compartment296containing a bearing and a scavenger pump298. The line from the bearing compartment296to the scavenger pump298may be referred to as a scavenger line.

The supply pump292when operated provides a lubricant (e.g., oil or equivalents thereof) from the oil reservoir294to the at least one bearing compartment296so that the bearing is properly lubricated and oil is also provided to the scavenger pump298that is fluidly coupled to the bearing compartment296and the oil tank or reservoir294. Operation of the scavenger pump298will cause oil to be drawn from the bearing compartment296by the scavenger pump298. In some non-limiting embodiments disclosed herein, independent operation of the scavenger pump298will cause the pressure within the bearing compartment296to be reduced. The scavenger pump298also provides the oil received from the bearing compartment296to the oil reservoir294. Although only one bearing compartment296is illustrated in the FIGS. it is of course understood that the lubrication system288may have multiple bearing compartments or a plurality of bearing compartments296. Still further and although only one supply pump292and scavenger pump298are illustrated it is, of course, understood that various embodiments of the present disclosure contemplate multiple supply pumps292and/or scavenger pumps298.

In accordance with one embodiment of the present disclosure, the motor282is operably coupled to the low speed spool30or low speed rotor30or the high speed spool32or high speed rotor32and the supply pump292or the scavenger pump298. By incorporating the lubrication system288into a hybrid electric system or engine, the availability of electric power in a hybrid electric system or engine allows for improved oil containment while benefiting from the hybrid electric engine in a geared turbofan engine or a gas turbine engine (e.g., non-geared turbofan engine). It being understood that various embodiments of the present disclosure are applicable to a hybrid electric engine comprising a geared turbofan engine or a gas turbine engine (e.g., non-geared turbofan engine) or any equivalent engine.

In one embodiment, an electric motor, which may be motor282or motor212A or motor212B drives either the high speed spool32or the low speed spool30which also drives the supply pump292or scavenger pump298mechanically coupled to the spools (e.g., high and/or low) of the engine. The benefit of driving the supply pump292or scavenger pump298by electrically driving the spools as opposed to driving the spools of the engine via combustion of fuel or a limited amount of fuel combustion, seal pressures in the lubrication system288can be controlled. As used herein, seal pressure may refer to the pressure differential between an interior and exterior of the bearing compartment(s)296. In other words, the seal of the bearing compartment296is subject to the pressure differential between the interior and the exterior of the bearing compartment296and the seal is used to keep the lubricant within the bearing compartment296.

As such, control of this pressure differential is advantageous in maximizing the efficiency of the seal of the bearing compartment. For example and in order to maintain lubricant in the bearing compartment, it is desirable to maintain the pressure in the bearing compartment296at a desired pressure for optimal performance. As used herein, the desired pressure may be a pressure that keeps the pressure differential between the interior and the exterior of the bearing compartment296at a value where oil is not passed from the interior of the bearing compartment to the exterior of the bearing compartment through a seal of the bearing compartment. In addition, the desired pressure may be a pressure that keeps the pressure differential between the interior and the exterior of the bearing compartment296at a value where air is not forced into the bearing compartment296through a seal of the bearing compartment296.

In various embodiments of the present disclosure, the pressure differential acting upon a seal of the bearing compartment296is controlled by operation of the supply pump292and/or the scavenger pump298and/or the spools (e.g., high and/or low) of the engine where the supply pump292and/or the scavenger pump298are mechanically coupled to the spools (e.g., high and/or low) of the engine. Still further, operation of the engine where via combustion of fuel (e.g., fuel provided to combustor56as is known in the related arts) may also affect the pressure differential acting upon a seal of the bearing compartment296due to air flows created during operation of the compressor section of the engine.

The operational connection of motor282to the spools30,32and the pumps292,298is illustrated by the lines inFIG.5. By incorporating the lubrication system288into a hybrid electric system or engine, the availability of electric power in a hybrid electric system or engine allows for improved oil containment while benefiting from hybrid electric engine in a geared turbofan engine or any other gas turbine engine (e.g. a non-geared turbofan engine). For example and in this embodiment, the pumps292,298are driven by the spools30and/or32. Here, the motor282may supplement the rotational speed of the spools30and/or32and oil containment in the bearing compartment296may be facilitated by driving the pumps292,298without combustion of fuel and/or a reduced amount of fuel supplied to the combustor56. In other words, electrically driving the spools30and/or32also allows for enhanced oil containment in the bearing compartment(s)296by controlling the electrical operation of the pumps292,298via controlling operation of motor282that is operably coupled to the spools30and/or32.

Referring now toFIG.6, a schematic illustration of the lubrication system288in accordance with various embodiments of the present disclosure is illustrated. In this embodiment, a supplemental motor283is provided for driving the supply pump292and/or the scavenger pump298while motor282, or motor212A or motor212B is provided for driving the high and low spools30,32. In this embodiment, the supply pump292and scavenger pump298are mechanically decoupled from the high and low spools30,32. As previously mentioned, oil containment in the bearing compartment296may be facilitated by electrically driving the pumps292,298. In this embodiment, the supply pump292and the scavenger pump298are mechanically decoupled from the high and low spools30,32and thus control of supplemental motor283controls operation of the pumps and the pressure differential of the seal or seals of the bearing compartment(s) is facilitated by controlling motor283as well as motor282.

Again and by electrically driving the spools30,32as opposed to driving the spools30,32via combustion of fuel in the combustor56, seal pressures of the bearing compartment(s)296are controlled in a more robust manner. For example, by using electrical assist to anyone of the high speed spool or rotor32, the low speed spool or rotor30, the supply pump292and the scavenger pump298, the internal pressure in the bearing compartment is managed so that oil is maintained in the bearing compartment(s)296. The operational connection of motor282to the spools30,32and motor283to the pumps292,298is illustrated by the lines inFIG.6.

Still further and in the embodiment illustrated in at leastFIG.6, the controller256is operable to control the supplemental motor283based upon an operational condition of the hybrid electric propulsion system, which as mentioned above, may be the pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment. In yet another implementation, the operable operational condition of the hybrid electric propulsion system is a rotational speed of the low speed spool and/or the high speed spool. This rotational speed may be provided by one or more sensors operably coupled to the controller and configured to provide an indication of the rotational speed of the low speed spool and/or the high speed spool. Rotational speed of the low speed spool and/or the high speed spool may affect oil containment in the bearing compartment as pressures outside of the bearing compartment may vary due to variations in the rotational speed of the low speed spool and/or the high speed spool, which may be attributable to operating the first electric generator213A configured to convert rotational power of the low speed spool30to electric power and/or the second electric generator213B configured to convert rotational power of the high speed spool32to electric power. In other words, operation of the first electric generator213A and/or the second electric generator213B may slow the rotation of the low speed spool and/or the high speed spool which may affect the pressure differential at the seal of the bearing compartment. Alternatively, this slowing of the low speed spool and/or the high speed spool may be due to the electric motor282or one or more of the electric motors212A,212B being configured as a motor or a generator depending upon an operational mode or system configuration.

In yet another alternative and as illustrated inFIG.7, a separate motor can be provided for each of the supply pump and the scavenger pump. This additional motor is illustrated as motor285inFIG.7. As previously mentioned, oil containment in the bearing compartment296may be facilitated by electrically driving the pumps292,298. In this embodiment, the supply pump292and the scavenger pump298are mechanically decoupled from the high and low spools30,32and thus control of motors283and285controls operation of the pumps and the pressure differential of the seal or seals of the bearing compartment(s) is facilitated by controlling motors283and285as well as motor282. In this embodiment, operation of the supply pump292is independent of scavenger pump298as well as rotation of spools30and32.

Still further and in the embodiment illustrated in at leastFIG.7, the controller256is operable to control motor283and/or motor285based upon an operational condition of the hybrid electric propulsion system, which as mentioned above, may be the pressure differential between an interior of the bearing compartment and an exterior of the bearing compartment. In yet another implementation, the operable operational condition of the hybrid electric propulsion system is a rotational speed of the low speed spool and/or the high speed spool. This rotational speed may be provided by one or more sensors operably coupled to the controller and configured to provide an indication of the rotational speed of the low speed spool and/or the high speed spool. Rotational speed of the low speed spool and/or the high speed spool may affect oil containment in the bearing compartment as pressures outside of the bearing compartment may vary due to variations in the rotational speed of the low speed spool and/or the high speed spool, which may be attributable to operating the first electric generator213A configured to convert rotational power of the low speed spool30to electric power and/or the second electric generator213B configured to convert rotational power of the high speed spool32to electric power. In other words, operation of the first electric generator213A and/or the second electric generator213B may slow the rotation of the low speed spool and/or the high speed spool which may affect the pressure differential at the seal of the bearing compartment. Alternatively, this slowing of the low speed spool and/or the high speed spool may be due to the electric motor282or one or more of the electric motors212A,212B being configured as a motor or a generator depending upon an operational mode or system configuration.

Still further and in yet another alternative embodiment an electrically actuatable valve299may be located in the lubrication system288of any of the aforementioned embodiments. The electrically actuatable valve299can be controlled by controller256in order to control the changes in pressure in the bearing compartment296in combination with controlling the speed of the supply and/or scavenger pump as well as spools30and32. Although one specific location is illustrated for valve299any other suitable location is contemplated to be with the scope of various embodiments of the present disclosure. Still further and in yet another alternative, the lubrication system288of any of the aforementioned embodiments may have a plurality of valves299.

As used herein control of the changes in pressure in the bearing compartment296in order to manage or maintain the pressure differential at the bearing seal may be achieved by receiving pressure signals from a sensor or pressure sensor301located in the lubrication system288, For example, a sensor or pressure sensor301may be located in the bearing compartment(s)296as well as a sensor or pressure sensor305located outside of the bearing compartment(s)296so that a pressure differential between the interior or exterior of the bearing compartment(s)296can be determined. As such, the sensor or pressure sensor301will be able to provide an indication of the pressure (e.g., oil pressure or other equivalent pressure reading) in the bearing compartment(s)296and the sensor or pressure sensor305will be able to provide an indication of the pressure outside of the bearing compartment(s)296(e.g., air pressure or other equivalent pressure). The sensors or pressure sensors301,305are in operable communication with the controller256. Although one specific location is illustrated for sensors or pressure sensors301,305any other suitable location for providing the required pressure readings is contemplated to be with the scope of various embodiments of the present disclosure. It is, of course, understood that the pressure sensors301and305may be used in conjunction with any of the aforementioned embodiments.

Bearing compartment296will include a seal303in order to contain the oil in the bearing compartment(s)296of the bearing. It is, of course, understood that the seal303is used in conjunction with any of the aforementioned embodiments. In one embodiment, the seal303may be a non-contact seal in order to contain the oil within the bearing compartment. Alternatively and in yet another embodiment, the seal303may be a contact seal in order to contain the oil within the bearing compartment.

Control means for controlling the lubrication system288of any of the aforementioned embodiments can be a controller or other suitable control system such as controller256(FIGS.2-7) for receiving output signals representing sensed data from the operably connected components of the lubrication system288.

In one embodiment and as mentioned above, the controller256can control and monitor for fault conditions of the gas turbine engine120and/or the electrical power system210. For example, the controller256can include a processing system260, a memory system262, and an input/output interface264.

The input/output interface264is configured to collect sensor data from the one or more system sensors and interface with various components and subsystems, such as the lubrication system288and components thereof as well as components of the motor drive electronics214A,214B, rectifier electronics215A,215B, energy storage management system216, integrated fuel control unit222, actuators224, and/or other components (not depicted) of the hybrid electric propulsion system or hybrid electric engine100. Thus, the controller256provides a means for controlling the hybrid electric system control effectors240based on a power transfer control266that is dynamically updated during operation of the hybrid electric propulsion system or hybrid electric engine100. The means for controlling the hybrid electric system control effectors240can be otherwise subdivided, distributed, or combined with other control elements.

The power transfer control266can apply control laws and access/update models to determine how to control and transfer power to and from the hybrid electric system control effectors240. For example, sensed and/or derived parameters related to speed, flow rate, pressure ratios, temperature, thrust, fuel flow, power provided by motor282, power provided by motor283, power provided by motor285and the like can be used to establish operational schedules and transition limits to maintain efficient operation of the gas turbine engine120.

As such, the controller256is capable of controlling the lubrication system288by sensing the aforementioned parameters related to speed, flow rate, pressure ratios, temperature, thrust, fuel flow, power provided by motor282, power provided by motor283, power provided by motor285and the like. Once, the controller determines that the engine120is in an operating condition that requires actuation of the lubrication system288it causes power to be supplied from a power source280to the lubrication system288in order to provide the lubrication.

For example and in one non-limiting embodiment, the controller256in any of the aforementioned embodiments can enhance or control oil containment in the bearing compartment(s)296by controlling operation of motor282, motor283, and motor285by providing power thereto or limiting power thereto in order to control a pressure differential at the seal303of the bearing compartment(s)296. As mentioned above, control of motor282, motor283, and motor285may be dependent upon signals received from sensors301and305as well as other operational parameters (e.g., speed, flow rate, pressure ratios, temperature, thrust, fuel flow). It is, of course, understand that other operational parameters are considered to be within the scope of various embodiments of the present disclosure.

As used herein radially outward is intended to be in the direction away from the engine central longitudinal axis A.