Abstract
Drive means for connecting a gas turbine engine to its accessories are constructed as to enable accessories to be positioned selectively in any one of several predetermined circumferential positions about the perimeter of the motor. This feature enables convenient mounting of the same engine in vehicles that require radically different engine mounting arrangements.
Description
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305of the Act National Aeronautics and Space 1958, Public Law 85-568 (72 Stat 435. 42 USC 2457).
Backround of the invention
This invention relates to gas turbine engines and, more particularly, to the engine-driven accessories for use therewith.Jet engines for powering aircraft are equipped with engine driven accessories to provide an essential service and regulatory functions. These accessories are typically mounted in the structure of the motor casing and, like the rest of the engine, usually are enclosed in a simplified structure or other nacelle surrounding the engine to reduce the aerodynamic resistance in general. However, as the complexity of accessories constantly increases, and the space available inside the nacelle at best remains the same, the designer of gas turbine engine is faced with the dilemma of where to place the fittings so as not Gondola diameter increases with consequent drag penalties.The problem is compounded when the gas turbine designers also face having to set up their engines for several unique applications demanding radically different engine mounting arrangements. For example, in the field of aeronautics, it is contemplated that the same basic aircraft engine find application in conventional aircraft with under-the-wing (UTW) mounting pylon, and yet may also be necessary to adapt to aircraft that is over-the-wing (OTW assembly) engine. The last setting seems very attractive for short takeoff aircraft and landing (STOL) which use the exhaust gas turbine engine aircraft wing to provide lift augmentation by the Coanda effect blowing across the top surface of a system flaps and connected.Since the essential accessories are driven by the aircraft gas turbine engine, it is common to locate the aircraft and engine accessories in close relative proximity to be driven by a common shaft of engine power. In advanced engines, such as CF6-50 from General Electric, all accessories driven by the motor are mounted in a gearbox housing is located in the engine fan at the bottom of the engine within the nacelle . However, this provision requires relatively complex plumbing for operatively connecting accessories to the aircraft, as the accessories are in the bottom of the engine while the engine is typically suspended wing of the aircraft by a structure known as a pylon, the junction which is at the top of the engine.It can be seen therefore that in order to obtain highly simplified nacelles, such as taught in copending application Ser. No. 592108, filed on November 8, 1974, Adamson et al, "A gas turbine engine built-gondola," assigned to the same assignee as the present invention, and yet maintain flexibility in motor mounting configurations, would be advantageous to have the engine driven accessories external to the gondola and the location is consistent with optimal peripheral particular aircraft installation. Ideally, any particular engine should not be limited to a single location for your accessories circumferential driven as this will prevent a plane change UTW OTW an aircraft without engine disassembly and reassembly to replace incompatible hardware. It is conceivable, as evidenced by the current trend of airlines to standardize its fleet, an engine can be used in more than one type of aircraft application. The problem faced by the engine manufacturer, therefore, is to provide an accessory device that allows adaptation to different configurations of the engine of the aircraft, and additionally provide steamlining gondola. Although this invention is directed in particular to aircraft propulsion systems, it will be apparent that the invention is equally applicable to all vehicles that use propelling gas turbine engine.
SUMMARY OF THE INVENTION
The object of the present invention, therefore, is to provide an accessory drive arrangement convertible, preferably external to the gas turbine engine nacelle, which provides flexibility for various mounting configurations. This and other objects and advantages will be more clearly understood from the following detailed description, drawings and specific examples, all of which are intended to be typical of rather than in any way limiting the scope of the present invention.
Briefly, the above object is achieved by locating the engine accessory package external to the nacelle structure such that it fits within a cavity formed within the aircraft or pylon. A drive shaft extending from the accessory package through a hollow strut in engagement with the main axis of the core engine for driving connection of the compressor and turbine portions. At least one hollow strut is provided so that, if it is desirable to relocate fixtures, which can be withdrawn and removed from the drive shaft of the first strut. Subsequently, the drive shaft can be reinstalled in the second hollow strut therefore re-engage in drive connection shaft core engine and accessories.
DESCRIPTION OF DRAWING
. Figure 1 is a schematic representation of a composite gas turbine engine embodying the present invention, the motor is mounted on either of the two different configurations, and. Figure 2 is a schematic enlarged compound represents an embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in which like numbers refer to like elements throughout, reference is first directed to FIG. 1 in which a motor is shown generally at 10 and embodying the present invention is shown schematically. This engine can be considered that generally comprises a core engine 12, a fan assembly 14 including a stage of fan blades 15, and a blower wheel 16 that is interconnected with the fan assembly 14 for shaft 18 . The core engine 12 includes an axial flow compressor 20 having a rotor 22. Air enters the inlet 24 and is initially compressed by the fan assembly 14. A first part of this compressed air enters the fan bypass duct 26 is defined partly by the core engine 12 and a fan nacelle 28 which circumscribes and discharges through a fan nozzle 30. A second portion of compressed air entering the inlet 32, is further compressed by axial flow compressor 20 and then discharged to a combustor 34 where fuel is burned to provide combustion gases to drive a high energy turbine 36. Turbine 36, in turn, drives the rotor 22 through a shaft 38 in the usual manner of a gas turbine engine. The hot combustion gases then pass to and drive the turbine fan 16 which, in turn, drives fan assembly 14. A propulsion force is thus obtained by the action of assembly 14 of the fan discharge air fan bypass duct 26 through the fan nozzle 30 and the discharge of combustion gases from a nozzle core engine 40 is defined in part by the cap 42. The foregoing description is typical of many gas turbine engines today and are not intended to be limiting, as will be readily apparent from the following description that the present invention is capable of application to any turbine engine and gas is not necessarily restricted to gas turbine engines of the turbofan variety. The foregoing description of the operation of the engine shown in FIG. 1 is therefore only intended to be illustrative of an application type.Continuing with the description of the embodiment of the invention as shown in the top of the figure. 1, there is shown therein the engine 10 is suspended from a pylon is shown generally at 44, which, in turn, is suspended from and integral with an aircraft wing 46 through 48 lattice structure. The mounting system of aircraft propulsion discussed herein are provided as an example of the possible uses of the present invention as will be apparent that the invention is equally applicable to all vehicles using the gas turbine propulsion. This configuration is representative of the band below the motor mounting (UTW). Pylon 44 is shown to include, and are arranged inside, aircraft accessories generally represented at 50. Accessories critical engine generally represented by 52 are located within a cavity 54 of the tower 44 even though they are an integral part of the engine hardware. Suitable disconnections are provided, as at 55 and 57, to enable separation of the engine pylon and aircraft accessories. Engine accessories are connected to drive the core engine 12 through a driving means such as a drive shaft 56 which is routed through one of a plurality of struts 58 which passes through the bypass duct Fan 26.Referring now to FIG. 2 is shown schematically in greater detail the accessory drive arrangement of Fig. 1. The top half of the figure. 2 is consistent with the OTW mounting arrangement discussed hereinabove. The core engine shaft 38 is shown to have integral therewith a first engagement means, such as bevel gears 60. Drive shaft 56 includes a second gear means such as the bevel gear 62, which engages bevel gear drive 60 as at 64. Drive shaft 56 is operatively connected to an engine accessory drive shaft coupling 66 by known means such as meshed bevel gears 68 and 70, the accessory drive shaft 66 being an integral part of the engine accessories generally denoted 52. Aircraft accessories, generally denoted 50, are connected to drive shaft 56 through cooperation bevel gears 72 and 74, and shaft 76.In a modified configuration is shown in Fig ghost. 1 and 2, the engine accessory package is adapted for an engine mounting arrangement on-the-wing. As shown in dashed lines in Fig. 1, there is shown therein the engine 10 is mounted on a wing 46 'by means of cooperation mounting pylon 44'. The accessories of the motor 52 'are mounted under the engine here, external to the nacelle 28 and located within tower 44. Again, the engine accessories are drivingly connected to the core engine 12 by means of the drive shaft 56 'has now been inserted through a hollow post 58' at the bottom of the motor. Aircraft fixtures 50 'are located further aft in this configuration as a result of special consideration and are driven by the shaft 78.As clearly shown in dashed lines in Fig. 2, the meshing of the bevel gears 60 and 62 'occurs in the 64', but by virtue of bevel gears 68 'and 70', the rotational direction of the accessory drive shaft 66 'is unchanged as shown by the rotation arrows. This ensures proper operation of all components and accessories without the need for modification.In operation, when the engine is desired to switch from one configuration to a configuration UTW OTW, the operator simply disconnecting 52 engine accessories 50 aircraft accessories, pull the engine accessories and the drive shaft 56 of the strut 58 and the core commitment of the shaft 38, and reinsert the assembly into another hollow strut 58 'thereby compromise with the central axis 38 is reset. Alternatively, a plurality of drive shafts such as 56 and 56 ', may remain operatively connected to central shaft 38 with the engine point disconnect fitting occurs between the gears 68 and 70. Blank-off plates suitable (not shown) serve to cover the shafts are not in use. This provision would apply when you want to mount the engine accessories pylon structure and make it stay there when the engine and nacelle structure has been removed from the aircraft. This arrangement is particularly attractive from the point of view aircraft operator as it needs to keep a supply of accessories approximately equal to their aircraft requirements, regardless of the number of spare engines on hand. Therefore, the operator can maintain a minimum engine accumulation unit comprising engine components required minimum, thereby increasing its ability to quickly change-engine. Yet another alternative is to include redundant drive shaft gears 62 and 62 '(Figure 2) permanently installed on the engine, the rest of the drive shaft 56 is constructed so as to permit a driving connection with both gear. This arrangement is attractive where the gear required size is larger than the available hole through which otherwise would have to go.It should be obvious to one skilled in the art that certain changes can be made to the invention described above without departing from the broad inventive concepts thereof. for example, as mentioned above, the above invention is applicable to any gas turbine engine and is not limited to the variety of turbofan gas. Furthermore, it is contemplated that alternative gear arrangements are possible in order to achieve the broad inventive concepts of the present invention. Furthermore, it is readily apparent that the present invention is not limited to applications over-the-wing and under-the-band, but is applicable when it is desired accessories convertibility between any two or more mounting locations in any engine accessories gas turbine powered vehicle.It is intended that appended claims cover all such variations and similar broader inventive concepts of the present invention.
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