DRIVE SYSTEM ARRANGEMENT FOR ROTARYWING AIRCRAFT

Description

[0001] The subject matter disclosed herein relates to the rotary wing aircraft and, more specifically to power distribution from engines of a rotary wing aircraft.

[0002] In some rotary wing aircraft configuration, one or more engines are used to drive both a main rotor system, which provides lift to the aircraft, and a translational thrust or propulsor system. Power is extracted from the engine via a turboshaft arrangement as shown in FIG. 5. Power is extracted via the shaft 100 at one end of the engine 102 and to a gearbox 104. The gearbox 104 is utilized to transfer the power from the shaft 100 to a main rotor assembly 106. Further, an auxiliary shaft 108 is operably connected to the gearbox 104 to extract power from the gearbox 104 for use by a propulsor 110. Such an arrangement is complex, requiring multiple shafts and power take offs to drive the propulsor110. Further, depending on the propulsor location relative to the main rotor assembly 106, for example, a tail mounted propulsor 110, a long shaft assembly extending from the gearbox 104 is required to reach the propulsor 110 location. A simpler, less complex drive system for the propulsor is desired.

[0003] US 2009 / 0140182 A1 shows an actuation mechanism for use in a convertible gas turbine propulsion system comprises a plenum, a pneumatically powered drive body and a spring system. The plenum receives pressurized air from the convertible gas turbine propulsion system. The pneumatically powered drive body is connected to the plenum to receive pressurized air to axially move the drive body in a first direction.

[0004] US 3 483 696 A shows a power plant for a helicopter having a rotor and comprising a gas turbine engine having a free turbine, a shaft, a fan drivingly connected to the shaft, and mechanical drive means for mechanically rotating the helicopter rotor.

[0005] US 2010 / 0154435 A1 shows a turbine engine for a VTOL aircraft. The core of the turbine engine includes two spools-a low pressure (LP) spool and a high pressure (HP) spool-where the LP spool is independently mounted remote to the HP spool. The engine is modulated for operation by a modulation diverter valve assembly and through the fuel flow to the engine. The power output from the engine can be modulated from high levels to low levels and vice versa through control of the air flow through the engine using the modulation diverter valve assembly.

[0006] US 3 375 997 A shows a compound gas turbine powerplant comprising a cylindrical casing having an inlet and an outlet at opposite ends thereof, compressor means, combustion means, first turbine means for driving said compressor means, and second turbine means axially disposed within said casing and forming therewith a motive fluid passage extending axially between said inlet and said outlet.

[0007] The present invention relates to a rotorcraft according to the appended claims. Embodiments are disclosed in the dependent claims.

[0008] In an embodiment the main rotor input shaft extends from the first engine in a first direction, and the auxiliary input shaft extends from the second engine in a second direction opposite the first direction.

[0009] Additionally or alternatively, in this or other embodiments the main rotor input shaft extends from the rotor power turbine through the compressor section to connect with the main rotor assembly.

[0010] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The subject matter is particularly pointed out and distinctly claimed at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is a schematic view of an embodiment of a rotary wing aircraft; FIG. 2 is a schematic view of an example of a drive system arrangement for a rotorcraft useful for understanding the invention; FIG. 3 is a schematic view of another example of a drive system for a rotorcraft useful for understanding the invention; FIG. 4 is a schematic view of an embodiment of a drive system for a rotorcraft; and FIG. 5 is a schematic view of a prior art drive system arrangement.

[0012] Shown in FIG. 1 is schematic view of an embodiment of a rotary wing aircraft, in this embodiment a helicopter 10. The helicopter 10 includes an airframe 12 with an extending tail 14. A dual, counter rotating coaxial main rotor assembly 18 is located at the airframe 12 and rotates about a main rotor axis 20. The main rotor assembly 18 is driven by a power source, for example, an engine 24 via a main rotor gearbox 26. The main rotor assembly 18 includes an upper rotor assembly 28 driven in a first direction 30 about the main rotor axis 20, and a lower rotor assembly 32 driven in a second direction 34 about the main rotor axis 20, opposite to the first direction 30.

[0013] While, in FIG. 1, the first direction 30 is illustrated as counter-clockwise and the second direction 34 is illustrated as counter clockwise, it is to be appreciated that in some embodiments the directions of rotation of the upper rotor assembly 28 and lower rotor assembly 32 may be reversed. Each of the upper rotor assembly 28 and the lower rotor assembly 32 include a plurality of rotor blades 36 secured to a rotor hub 38. In some embodiments, the helicopter 10 further includes a translational thrust system 40 located at the extending tail 14 to provide translational thrust for the helicopter 10. The translational thrust system 40 includes an auxiliary rotor, such as a propeller rotor or propulsor 42 connected to and driven by the engine 24. While shown in the context of a pusher-prop configuration, it is understood that the propulsor 42 could also be more conventional puller prop or could be variably facing so as to provide torque in addition to or instead of translational thrust.

[0014] FIG. 2 illustrates an example of a drive train arrangement for the helicopter 10 useful for understanding the invention. The helicopter 10 illustrated utilizes two gas turbine engines 24, while in other embodiments other numbers of engines 24, for example, one or three engines 24, may be utilized. The engines 24 are arranged such that one engine 24 is located at each lateral side of the helicopter 10, with reference to aircraft longitudinal axis 46. Each engine 24 has a compressor section 48 located nearest a forward end 50 of the engine 24 and a turbine section 52 located aft of the compressor section 48. The turbine section 52 extracts work from combustion gases to drive the compressor section 48.

[0015] Each engine 24 additionally includes a rotor power turbine 54 at the turbine section 52. The rotor power turbine 54 is connected to a rotor input shaft 56 extending through the compressor section 48 and toward the main rotor gearbox 26. The rotor power turbine 54 extracts rotational energy from the engine 24 and transmits the rotational energy to the main rotor gearbox 26 via the rotor input shaft 56. The main rotor gearbox 26 transmits the rotational energy to the main rotor assembly 18 to drive the upper rotor assembly 28 and the lower rotor assembly 32.

[0016] Each engine 24 further includes a propulsor power turbine 58 connected to a propulsor input shaft 60. The propulsor input shaft 60 extends from the turbine section 52 in a direction opposite the rotor input shaft 56, in some embodiments, rearwardly with reference to normal helicopter flight orientation. The propulsor power turbine 58 extracts rotational energy from the engine 24 and transmits the rotational energy to the propulsor 42 via the propulsor input shaft 60. In some embodiments, a propulsor gearbox 62 connects the propulsor input shaft 60 to the propulsor 42 to transfer the rotational energy from the propulsor input shaft 60 to the propulsor 42. In the example of FIG. 2, a first propulsor power turbine 58a of the first engine 24a drives a first propulsor and a second propulsor power turbine 58b of the second engine 24b drives a second propulsor. In an alternative example, shown in FIG. 3, both propulsor input shafts 60a, 60b are connected to and drive a single propulsor 42 via propulsor gearbox 62. In some embodiments, the rotor power turbine 54 and / or the propulsor power turbine 58 may have variable geometry blades that would allow tailoring within the engine 24 to allow extraction of the proper power and not severely and adversely impact the performance of the adjacent one. For example, in instances where power is not required for thrust via the propulsor power turbine 58, the blades of the propulsor power turbine 58 could be aligned more with the flow to minimize losses within the engine 24.

[0017] Referring now to FIG. 4, an embodiment of a drive train arrangement is shown. In the embodiment of FIG. 4, the first engine 24a solely drives the main rotor assembly 18 and the second engine 24b solely drives the propulsor 42. The first engine 24a has a rotor power turbine 54 at the turbine section 52. The rotor power turbine 54 is connected to the rotor input shaft 56 to drive the main rotor assembly 18. The second engine 24b includes propulsor power turbine 58 connected to a propulsor input shaft 60 to drive the propulsor 42.

[0018] While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. A rotorcraft (10) comprising: an airframe (12); a main rotor assembly (18) operably connected to the airframe, wherein the main rotor assembly is a dual, counter rotating coaxial main rotor assembly; an auxiliary rotor assembly (42) operably connected to the airframe (12); and a drive system disposed at the airframe (12) including: at least two engines (24a, 24b), each of the engines including: a compressor section (48); and a turbine section (52) disposed rearward from the compressor section; a first engine (24a) of the at least two engines having a main rotor input shaft (56) extending from a rotor power turbine (54) of the turbine section and operably connected to the main rotor assembly (18) to transfer rotational energy from the rotor power turbine to the main rotor assembly; and a second engine (24b) of the at least two engines having an auxiliary input shaft (60) extending from an auxiliary power turbine (58) of the turbine section and operably connected to the auxiliary rotor assembly (42) to transfer rotational energy from the auxiliary power turbine to the auxiliary rotor assembly (42) which is a propulsor, wherein in use, the first engine (24a) solely drives the main rotor assembly (18) and the second engine (24b) solely drives the auxiliary rotor assembly (42).

2. The rotorcraft of claim 1, wherein the main rotor input shaft (56) extends from the first engine (24a) in a first direction, and the auxiliary input shaft (60) extends from the second engine (24b) in a second direction opposite the first direction.

3. The rotorcraft of claims 1 or 2, wherein the main rotor input shaft (56) extends from the rotor power turbine (54) through the compressor section (48) to connect with the main rotor assembly (18).