Propeller pump system for handed propeller applications

BACKGROUND OF THE INVENTION

The present invention relates to a pump system, and more particularly to a pump system which may be interchangeably utilized for either a clockwise or counterclockwise propeller shaft rotation.

Multi-engine propeller aircraft utilize pump systems which are driven by a propeller system gearbox. Typically, a pump system is mounted to a bulkhead within an engine nacelle of each engine to locate the main pump in proximity to the propeller system and associated gearbox. On multi-engine propeller aircraft, the propeller on adjacent engines typically rotates in opposite direction to counteract torque. That is, the propeller system of engine one rotates clockwise, the propeller system of engine two rotates counterclockwise, the propeller system of engine three rotates clockwise, and the propeller system of engine four rotates counterclockwise. Although an advantage from a propulsion perspective, such alternating rotations complicate pump installations as the engine gearboxes are also rotating in opposite directions. The associated pump drive systems must accommodate these specific rotations.

Conventional pump systems include a male drive shaft that extends from the pump system. Such conventional pump systems are designed to be driven from either end by switching the shaft. That is, a mounting structure is located on one end of the pump and a relatively significant blanking plate is bolted to the unused end to close the unused end of the pump against full pump pressure. This permits any single pump to accommodate either a clockwise or counterclockwise driven propeller system.

Disadvantageously, such conventional pump systems require that a clockwise mounting plate, a counterclockwise mounting plate and blanking plate be carried on the pump system at all times which increases system weight. The male drive shaft must also be removed and replaced to the opposite side to change the pump system to an opposite propeller rotation position. Such changeover requires disassembly of the pump at a significant depot level maintenance facilities which may increase aircraft downtime. The changeover to assure proper drive direction is a relatively complicated procedure which may further complicates maintenance time and expense.

Accordingly, it is desirable to provide a lightweight engine driven pump system which accommodates either a clockwise or counterclockwise propeller shaft rotation.

SUMMARY OF THE INVENTION

A pump system according to the present invention includes an inlet port, a discharge port, a drive aperture and a drain aperture. The drive aperture and the drain aperture are interchangeable such that the pump system may be utilized on either a clockwise or counterclockwise driven propeller. A gearbox driven male pump drive shaft is mounted into either aperture such that the aperture which receives the drive shaft becomes the drive aperture while the other aperture becomes the drain aperture.

A first pump gear is the driver gear in meshing engagement with a second pump gear which is the driven gear. The pump gears each include external gears in meshing engagement which communicate the fluid around the outside of the gears to provide the fluid pumping action from the inlet port to the discharge port. Fluid which is not communicated to the discharge port eventually collects within the second pump gear and is communicated to a gearbox drain through the drain aperture. As either pumping gear may become the driver gear by receiving the male drive shaft, the pump system may accommodate either a clockwise or counterclockwise propeller gearbox.

The present invention therefore provides a lightweight engine driven pump system which accommodates either a clockwise or counterclockwise propeller shaft rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a general rear schematic view of a multi-engine aircraft for use with the present invention;

FIG. 2 is a perspective view of a pump system of the present invention;

FIG. 3 is an exploded view of a pump system of the present invention;

FIG. 4 is a sectional view of the pump system taken along line 4-4 in FIG. 2; and

FIG. 5 is a schematic view of fluid flow through the pump system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a general schematic rear view of a multi-engine aircraft 10. The aircraft 10 includes a multiple of engines 12 each mounted to an aircraft wing 14. Each engine 12 is typically contained within an engine nacelle 16 having a bulkhead 18 through which passes a propeller shaft 20 to drive a propeller system 22 about an axis of rotation A.

A pump system 24 (FIG. 2) is mounted to each bulkhead 18 within the nacelle 16 of each engine 12. The pump system 24 is driven by a propeller gearbox 26 (illustrated schematically). On multi-engine prop aircraft, the propeller system 22 on adjacent engines 12 typically rotate in opposite direction (illustrated by arrow R) to counteract torque. That is, the propeller shaft 20a of engine one 12a rotates clockwise, the propeller shaft 20b of engine two 12b rotates counterclockwise, the propeller shaft 20c engine three 12c rotates clockwise and the propeller shaft 20d of engine four 12d rotates counterclockwise as respectively driven by the gearbox 26.

Such an alternating propeller rotation scheme requires that each associated pump system 24 be driven in a direction commensurate therewith. A mounting pad 27 is attached to each bulkhead 18 to mount the pump system 24 such that a pump drive shaft 28 rotates in a rotational direction (illustrated schematically by arrow r) relative to the propeller shaft 20 rotational direction R. The pump drive shaft 28 is preferably a male splined shaft. Typically, the pump shaft 28 rotates opposite the propeller shaft 20, however, other rotational schemes are also usable with the present invention. The male pump drive shaft 28 extends through the mounting pad 27 and is driven by the propeller gearbox 26 to drive the pump system 24.

The pump system 24 includes an inlet port 30, a discharge port 32, a drive aperture 34 and a drain aperture 36 (FIG. 2). Notably, the drive aperture 34 and the drain aperture 36 are interchangeable such that the pump system 24 may be utilized on either a clockwise or counterclockwise driven propeller. That is, the male pump drive shaft 28 is mounted into either aperture 34, 36. Whichever aperture 34, 36 the drive shaft 28 is installed into becomes the drive aperture 34 while the other aperture 36, 34 becomes the drain aperture 36.

Preferably, a locator pin 38 extends from the mounting pad 27 and is received into a locating aperture 40 formed into a seal plate 54 of pump housing 42 (FIG. 2). Notably, the locating pin 38 is in opposite positions on the mounting pad 27 depending upon whether the propeller system is clockwise or counterclockwise driven to assure proper mounting of the pump system 24. The locating aperture 40 is in only a single position on the pump system 24 (FIG. 2) to assure that fluid is pumped from the inlet port 30 to the discharge port 32 irrespective of which handed propeller gearbox the pump system 24 is mounted to.

The inlet port 30 and the discharge port 32 are preferably located opposite each other and are spaced generally horizontally relative the vertically mounted apertures 34, 36. Such arrangement permits the drain aperture 36 to always be at the lowest point when the pump system 24 is mounted to the aircraft (FIG. 1). It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” “horizontal,” “vertical,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.

Referring to FIG. 3, the pump system 24 generally includes the pump housing 42, a relief valve assembly 44, a discharge check valve assembly 46, a first and second floating bearing 48a, 48b, a first and second pump gear 50a, 50b, a first and second fixed bearing 52a, 52b and a seal plate 54. A multitude of seals S assure a fluid seal between the rotating components when the seal plate 54 is fastened to the pump housing 42 by a multitude of fasteners f.

Referring to FIG. 4, the first pump gear 50a, the first floating bearing 48a and the first fixed bearing 52a defines a gear system along a first axis of rotation P₁. The second pump gear 50b, the second floating bearing 48b and the second fixed bearing 52b defines a gear system along a second axis of rotation P₂. The axes of rotation are P₁ and P₂ are parallel and generally transverse to a line L drawing between the inlet port 30 and discharge port 32 (FIG. 2).

The first and second pump gear 50a, 50b each include an internal female spline 54a, 54b and an external gear 56a, 56b. The internal female spline 54a, 54b are equivalent and splined to receive the drive shaft 28 (FIG. 5). The drive shaft 28 extends from the propeller gearbox 26 (FIG. 5) and is pressed into the appropriate internal female spline 54a, 54b depending upon whether the gearbox is of clockwise or counterclockwise rotation. Preferably, such installation may be accomplished at a field level environment.

Either internal female spline 54a, 54b interchangeably receive the drive shaft 28 such that when the first internal female spline 54a receives the drive shaft 28, the first pump gear 50a is the driver gear, the first internal female spline 54a becomes the drive aperture 34, and the second internal female spline 54b becomes the drain aperture 36. Alternatively, when the second internal female spline 54b receives the drive shaft 28, the second pump gear 50b is the driver gear, the second internal female spline 54b becomes the drive aperture 34, and the first internal female spline 54a becomes the drain aperture 36.

Referring to FIG. 5, the first pump gear 50a is the driver gear in meshing engagement with the second pump gear 50b which is the driven gear. The external gears 56a, 56b communicate the fluid around the outside of the gears 50a, 50b to provide the fluid pumping action from the inlet port 30 to the discharge port 32. The gear mesh operates as a seal. Fluid which is not communicated to the discharge port 32 eventually collects within and around the second pump gear 50b and is communicated to a gearbox drain through the internal female spline 54a and the drain aperture 36.

It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit from the instant invention.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention.

The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.