HYBRID PROPULSION SYSTEM FOR AIRCRAFT

Hybrid powertrains for a fixed wing aircraft, a helicopter, and a V/STOL aircraft. A core of the jet engine rotates an integral generator without gear train, that provides current to charge batteries located in various locations on the aircraft. The batteries are used to power electric motors that provide the sole source of torque to fans, propellers, or rotors that propel the aircraft. These differ from the prior configurations by provisioning integrated architectures.

TECHNICAL FIELD

This disclosure relates to hybrid propulsion systems for airplanes, helicopters, short & vertical take-off and landing vehicles (S/VTOL).

BACKGROUND

Hybrid propulsion systems according to multiple exemplary aspects of the present disclosure combine at least one electrical power generator and at least one motor, and a driving fan/propeller (pusher or puller) in the nacelle for jet engines, including all embodiments of turbofan, turbojet, turboshaft, turboprop, and engines with afterburners for air vehicles. At least one motor drives the propeller or rotor(s) with its nacelle conformally integral with the wing or fuselage for facilitating vertical and short take-off and landing vehicles and helicopters. The exemplary hybrid propulsion system disclosed includes at least one electrical energy storage system located in one or more of the nacelle, wings or fuselage. The propulsion system uses power from both the gas turbine and electric storage system, or solely from electrical storage depending upon the thrust requirements on ground or in the air.

In the present-day aircraft (including fixed wing, vertical and short take off landing or hover crafts) engines, with single or multi spools, the propeller/fan is connected to a low-speed shaft of the jet engine either directly or through a transmission. The term “jet engine” (gas turbine) here refers to turboprop, turbofan and turbojet engine. The speed of rotation of the fan/propeller/rotor is based upon the rotational input from a shaft of the gas turbine engine directly or through mechanical transmission system and is not independently controlled. Hybrid propulsion systems conceptually include dual propulsion systems, one fuel system and one electric system, that are used to propel the vehicle. The architecture of hybrid systems include separate fuel systems and electrical systems. Power to propellers in such hybrid options is provided solely through electrical storage for running isolated electrical motors to turn propellers. An exclusively combined hybrid system as an integral unit is not known to Applicant to be currently in service.

In helicopter propulsion systems, the main rotor and tail rotor are powered by the jet engine through mechanical transmission system involving gear trains. The weight of the driveshaft and transmissions reduces the efficiency of the helicopter resulting in reduced fuel efficiency and vehicle range.

In vertical/short take-off and landing (V/STOL) vehicles, pivotable wing mounted engines generally have a jet engine that is separately located to power an electric motor that drives the propellers. In another concept of the vertical take-off and landing mode the entire propulsion system is pivoted to a vertical orientation with the axis of rotation of the jet engine, electric motor (for solely electric air vehicles), and propeller pivoting together. The entire propulsion system is pivoted to a horizontal orientation for normal flight. Pivoting the entire propulsion system in the case of a conventional turboprop engine requires a substantial supporting structure on the wings of the aircraft that adds weight and reduces efficiency. In another embodiment, the jet exhaust is pivoted for vertical takeoff and landing, with additional thrust vectoring nozzles, with a dedicated system making such a system inefficient.

This disclosure is directed to solving the above problems and other problems as summarized below.

SUMMARY

According to one aspect of this disclosure, a hybrid jet engine conformally integral to wing or fuselage/empennage is disclosed for a fixed wing aircraft. The propulsion system includes an engine housing including a fan compartment/nacelle that houses a low pressure compressor and a fan. A core compartment/nacelle houses a low pressure compressor, a high pressure compressor, a combustion chamber, a high and low pressure turbine section. A low speed spool is connected to the low pressure compressor and the low pressure turbine. A high speed spool is connected to the high pressure compressor and the high pressure turbine. An electric motor is disposed in the fan compartment and is not structurally connected to the low speed spool or the high speed spool. A fan is connected to the electric motor and is disposed in front of the electric motor. A generator is also disposed in the fan compartment, in front of the core compartment and is assembled to the low speed spool. At least one battery is disposed in the fan nacelle that receives current from the generator and provides current to the electric motor.

According to other aspects of this disclosure relating to the hybrid jet engine that may be provided as alternatives or optional features, the at least one battery may include a plurality of batteries assembled in the fan nacelle. At least one backup battery may be disposed in the fuselage and or wing dry bay of the fixed wing aircraft that provides current to the electric motor directly or indirectly. The batteries are interconnected, and the larger battery packs can be used to provide boost in case of additional power requirements. The electric motor may be a brushless electric motor. The electric motor may be disposed in a concentric relationship relative to the generator. Alternatively, the electric motor may be disposed in axially tandem orientation with the generator. The fan rotates at a speed that is controlled by a controller (comprised of inverter/converter and electronic control in collaboration with engine control) and is independent of the low speed spool and of the high speed spool. Fan performance is controlled to match the performance of the core. The fan motor can also be used as generator using appropriate control logic/circuit during certain phases of flight, such as flight and approach idle. A flexible joint may be provided between the generator and its connection to the spools, for architectural reasons.

According to another aspect of this disclosure, a hybrid helicopter is disclosed that includes a fuselage, a main rotor, and a tail rotor. A gas turbine engine has an axis of rotation, and the engine is assembled to the fuselage with the axis of rotation oriented in a longitudinal direction. A generator is driven by the jet engine to charge an energy storage system (e. g. batteries or capacitors) that receives current from the generator. A first electric motor rotates the main rotor and receives current from the energy storage system. A second electric motor rotates the tail rotor and receives current from the energy storage system. In general, the main rotor and the tail rotor are driven by power from the combination of generator and energy storage system directly or indirectly.

According to other aspects of this disclosure relating to the hybrid helicopter that may be provided as alternatives or optional features, the jet engine may have a high speed spool that drives the generator. Alternatively, the jet engine may have a low speed spool, and the generator may be driven by the low speed spool. The fuselage includes a cabin below the main rotor, and the energy storage system (e. g. battery) may be disposed as integral part of the fuselage. The main rotor may be driven directly by the first electric motor with no transmission operatively connected between the first electric motor and the main rotor. The tail rotor may be driven directly by the second electric motor with no transmission operatively connected between the second electric motor and the tail rotor. A speed reduction gear pair may be required for startup sequence.

According to a third aspect of this disclosure, a S/VTOL aircraft is disclosed that includes a fuselage and wings assembled to the fuselage. One or more propulsion systems may be attached to each of the right wing portion and the left wing portion of the S/VTOL aircraft. The S/VTOL propulsion system includes an electric motor and a propeller. At least one energy storage system is disposed in the wing and/or in the fuselage. The electric motors are pivotable relative to the wing with the axis of rotation of the propeller being pivoted between a horizontal orientation and a vertical orientation. A jet engine is assembled in a fixed position on the wing to provide thrust in the forward direction along with the propeller in cruise condition. A generator is rotated by the jet engine and provides current to the energy storage system.

According to other aspects of this disclosure relating to the vertical take-off and landing propulsion system that may be provided as alternatives or optional features, the generator may be disposed in a core nacelle and may be rotated by a high speed spool of the jet engine or a low speed spool of the jet engine. Additionally, a nozzle with thrust vectoring capability is envisioned to assist in aircraft control and S/VTOL configuration. Vectoring thrust nozzles incorporated within the propulsion system is a novel way to assist in S/VTOL aircraft operation, rather than turn the whole propulsion system. This is quite efficient in many ways, compared to the prior configurations.

The above aspects of this disclosure and other aspects will be described below with reference to the attached drawings.

DETAILED DESCRIPTION

Referring toFIG.1, a fixed wing aircraft10is illustrated that includes a fuselage12and a pair of wings14. A propulsion system16is assembled to each of the wings14. The term “jet engine” as used herein refers to a turbofan, turbojet, turboshaft, turboprop, and engines with afterburners. The propulsion system16provides propulsion and current to charge fan case battery packs18, fuselage battery packs20, and dry bay battery packs22.

Referring toFIGS.2and3, a turbofan propulsion system24for a commercial airplane is illustrated in perspective. A nacelle26includes an air inlet cowl28, a fan cowl30, and a core and thrust reverser cowl32. The exhaust system34includes a fan exhaust nozzle36and a core exhaust nozzle36and a plug38. A pylon40attaches the turbofan propulsion system24to the wing14.

Referring toFIG.3, the air inlet cowl28, fan cowl30, and core and thrust reverser cowl32are shown separated from a jet engine core42. A fan case44encloses a fan46and is enclosed by the fan cowl30. In one exemplary embodiment, the electric motor is a brushless electric motor. The fan46is driven by an electric motor48(shown inFIGS.4-6) that is independent from the jet engine core42. The term “independent” as used herein means that the jet engine core42does not provide mechanical torque to the fan46.

Fan case battery packs18provide current to the fan46and are assembled to the fan case44. By powering the fan46from the fan case battery packs18power is conserved because the mass of the aircraft can be reduced because the wiring for the electric motor48can be of reduced mass. The current provided to the electric motor48may, alternatively or in combination, be provided by a generator52(shown inFIGS.4-6), the fuselage battery packs20or the dry bay battery packs22. An electronic engine controller54, responsive to the propulsion requirements of the jet engine, selectively provides current to the electric motor48from one or more of the fan case battery packs18, the generator52, the fuselage battery packs20, or the dry bay battery packs22.

Referring toFIG.4, a partially cut-away fragmentary enlarged view of the fan case44, fan46are shown with a fan frame56, the generator52, and the electric motor48. In the illustrated embodiment, the motor48and generator52are assembled to the fan frame56in axial alignment with the central axis of the jet engine core42with the electric motor48in front of the generator52. The fan frame56supports bearings58that, in turn, support the fan46, the motor48, and the generator52for relative rotation. The generator52is rotated by the jet engine core42to produce current to charge the fan case battery packs18, the fuselage battery packs20, or the dry bay battery packs22. The generator52may also provide current to the motor48directly.

Referring toFIGS.5and6, an alternative arrangement is illustrated with a partially cut-away fragmentary enlarged view of the fan case44, fan46are shown with a fan frame56, the generator52, and the electric motor48. In the illustrated embodiment, the motor48and generator52are assembled to the fan frame56concentrically with each other and have a common axis of rotation with the electric motor48surrounding the generator52. The fan frame56supports bearings58that support the fan46, the motor48, and the generator52for relative rotation. The generator52is rotated by the jet engine core42to produce current to charge the fan case battery packs18, the generator52, the fuselage battery packs20, or the dry bay battery packs22.

In both the embodiments ofFIG.4and ofFIGS.5and6, The electric motor48is not driven by the jet engine core and does not receive any torque from the jet engine core42. Signal and power cables60(wiring) are routed through the fan frame56between the electronic engine controller54(controller/inverter), the battery packs (18,20, and22) and the generator52. A flexible joint62is provided between the generator52and the jet engine core42to absorb vibration and mitigate differential displacement from the jet engine core42, should the architecture demand.

Referring toFIG.7, a helicopter70is illustrated that includes a fuselage72, a main rotor74, a tail rotor76, and a jet engine16having an axis of rotation oriented in a longitudinal direction.

Referring toFIG.8, a turbojet engine78is illustrated in cross-section. The turbojet engine78does not include a fan and is an example of a propulsion system16that may be included in the helicopter embodiment (FIGS.7-9) or vertical/short take-off and landing (V/STOL) vehicles (FIGS.10-19). The turbojet engine78includes an inlet80that houses a generator82that is integral with the jet engine core84. The engine core84includes a compressor section86having a selected number of compressor blades88. A combustion chamber90is disposed behind the compressor86. A turbine section92receives exhaust from the combustion chamber90that is expelled from the turbojet engine78. The generator82is connected to one of the jet engine core s (not shown) and rotates with the jet engine core that provides torque to rotate the generator82.

Current is provided by the generator to the battery pack22described above with reference to the embodiments ofFIGS.4-6. However, the generator82does not provide current to any fan case battery packs50nor to any dry bay battery packs22. The fuselage battery packs20provide current to the main rotor74and tail rotor76of the helicopter70. In a V/STOL vehicle100the generator82provides current to either or both of the fuselage battery packs20and dry bay battery pack22.

Referring toFIG.9, a flow chart illustrates one example of the drive and control systems of the helicopter70. Two turbojet engines78that include an integral generator82provide current to an AC/DC converter102that converts the AC current to DC current to charge the fuselage battery pack20. The fuselage battery packs20provide current to a power distributor and speed controller104. An engine control system106responsive to the propulsion requirements and stabilization requirements of the helicopter70controls the power distributor and speed controller104. Current is provided to a main rotor electric motor108that rotates the main rotor and to a tail rotor electric motor110that rotates the tail rotor76. Engine control system106communicates with the power distributor and speed controller104to control the amount of current provided to the electric motors108and110and speed of rotation of the main rotor74and the tail rotor76.

Referring toFIGS.10and11, the V/STOL vehicle100is illustrated in two different operational modes. The V/STOL vehicle100includes two turboprop engines112InFIG.10, the V/STOL vehicle100is in a flying position with the axis of rotation of the propeller114oriented in a horizontal orientation to provide thrust in a forward direction. InFIG.11, the V/STOL is a take-off or a landing position wherein the axis of rotation of the propeller is oriented vertically to provide lift in a vertical direction. As used herein the term “horizontal” is a relative term in that the aircraft climbs and turns and is not always strictly horizontal. The term “vertical” is a relative term in that the aircraft may move partially in the horizontal direction during take-off and landing.

Referring toFIGS.12and13, the turboprop engine112is illustrated inFIG.12with the axis of rotation of the propeller114oriented in a horizontal direction to provide thrust in a forward direction. The propeller114inFIG.13is oriented in a take-off or a landing position wherein the axis of rotation of the propeller is oriented vertically along with the vector controlled exhaust nozzle126. This is achieved at the aircraft level with engine and aircraft control system coordination.

The turboprop engines112each include a brushless generator116that is disposed in an engine mount and support structure118and is housed in a turboprop nacelle. The propeller includes a pitch control mechanism (not shown) that is provided in combination with a brushless motor120. The turboprop engine112receives air through an inlet122, through a compressor gas turbine section124, and to the exhaust nozzle126. The compressor gas turbine section124may be an axial flow or centrifugal flow type of turbine. The motor120and propeller114are attached to the turboprop engine112by an articulating linkage128that is more fully described below with reference toFIGS.13-20.

Referring toFIG.13, the turboprop engine112is shown with the motor and pitch control systems rotated to the take-off and landing vertical thrust position by the articulating linkage128. The structure of the articulating linkage128may be altered with two embodiments being shown and described with reference toFIGS.14and15.

Referring toFIG.14, an intermediate hinge configuration is shown in greater detail wherein the articulating linkage128includes a lower linear actuator130, an upper linear actuator132and an intermediate hinge134that is supported by a stationary bracket136and is disposed between the lower linear actuator130and the upper linear actuator132. The support bracket and the actuation system are supported at the wing front spar and engine mount support structure142. The lower linear actuator130is extended and the upper linear actuator132is retracted to move the motor120and propeller114from the horizontal orientation to the vertical orientation for take-off and landing. The lower linear actuator130is retracted and the upper linear actuator132is extended to move the motor and propeller from the vertical orientation to the horizontal orientation for flight. The propeller and brushless motor120pivot about the intermediate hinge134.

Referring toFIG.15, a high hinge configuration is shown to include an upper hinge138that is supported by a bracket140attached to the wing front spar and engine mount support structure142. An intermediate linear actuator144and the lower linear actuator130are extended to move the motor120and propeller114from the horizontal orientation to the vertical orientation for take-off and landing. The intermediate linear actuator144and the lower linear actuator130are retracted from the vertical orientation to the horizontal orientation for flight. A hollow propeller shaft146is received in the brushless motor120and is aligned with the intermediate linear actuator144. The shaft146is such that it permits control/power cables162for pitch control mechanism shown inFIG.16to pass through.

Referring toFIGS.16and17, the articulated linkage128is shown with the motor and a pitch control linkage150. The pitch control linkage150includes the motor120with a spur/bevel gear152and worm gear pairs154. The spur gears152rotate the propellers114for pitch control.FIG.17is a cross-section showing the motor120and pitch control linkage150. A linkage for a two propeller system is shown but additional propellers may be added with additional linkages. This embodiment shows a concept of the pitch control mechanism using an electromechanical arrangement, however other means of pitch control mechanisms can be adopted and should be obvious to the skilled in the art.

Referring toFIGS.18and19, A split faring156is shown that includes a top faring158and a bottom faring160. The articulated linkage128is shown to be enclosed in the split faring156and is used to move the motor120and propeller114from the horizontal orientation to the vertical orientation for take-off and landing. The propeller114and motor120are shown in the cruise flight orientation inFIG.18and are shown in the take-off and landing position inFIG.19.

The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and includes modifications of the illustrated embodiments.