Patent Application
20120260769
This disclosure relates generally to a gearbox transfer tube and, more particularly, to a gearbox transfer tube that communicates some lubricant directly to an interior of the gearbox assembly.
Generators provide electric power as is known. Aircraft auxiliary power units, for example, typically include a generator that is driven by a turbine engine. The turbine engine is rotatably coupled to the generator through a gearbox.
Transfer tubes associated with the gearbox often carry fluid between different portions of the gearbox. The fluid moves from a first end of the transfer tube to an opposing, second end of the transfer tube. In one example, a transfer tube carries a lubricating fluid from a first side of the gearbox to an opposing, second side of the gearbox. The lubricating fluid is then communicated through one or more lubrication nozzles, which are separate from the transfer tube. The lubrication nozzles communicate a spray of lubricant directly to areas of the gearbox that need lubricating, such as interfaces associated with gears and bearings. Lubrication nozzles add complexity and weight to the gearbox assembly.
An example lubricating transfer tube assembly includes a transfer tube having a bore extending from a fluid inlet portion to a fluid outlet portion. The transfer tube is configured to communicate a fluid through the bore between the fluid inlet portion and the fluid outlet portion within a gearbox. The transfer tube defines a spray aperture extending from the bore to an outer surface of the transfer tube. The spray aperture is configured to communicate at least some of the fluid from the bore to an area of the gearbox.
An example auxiliary power unit gearbox assembly includes a housing establishing a gearbox cavity configured to receive a plurality of gears. A transfer tube establishes a bore. The transfer tube is configured to communicate a fluid from a first face of the housing to an opposing, second face of the housing. The transfer tube defines a spray aperture extending from the bore to a radially outer surface of the transfer tube. The spray aperture is configured to deliver a spray of the fluid to an area within the gearbox cavity.
An example method of lubricating an auxiliary power unit gearbox assembly includes positioning at least a portion of a gearbox transfer tube within a gearbox cavity of a gearbox. The method communicates lubricant through a bore of a gearbox transfer tube from a first end portion to second end portion of the transfer tube. The method moves some of the lubricant through an aperture in the transfer tube. The lubricant is moved directly to a portion of the gearbox cavity.
The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows:
Referring to
A lubricant l, or another type of fluid, moves from a lubricant supply 38 through a cooler 42 to the gearbox 22. The lubricant l moves along a lubricant path 46. The pump 36 is used to communicate the lubricant l along the lubricant path 46. The lubricant l is used to lubricate and cool at least the gears 26 within the gearbox 22.
The example lubricant path 46 includes a first conduit portion 50, a transfer tube 54, a second conduit portion 58, and a lubrication nozzle 62. In this example, the first conduit portion 50 and the second conduit portion 58 are located outside the gearbox 22, and the transfer tube 54 and the lubrication nozzle 62 are positioned within the gearbox 22.
The example transfer tube 54 is machined from aluminum. The example transfer tube 54 is sized to extend across a gearbox cavity from a first face 56a of a gearbox housing to an opposing, second face 56b of the gearbox housing. The example transfer tube 54 communicates the lubricant l across the gearbox cavity from the first conduit portion 50 to the second conduit portion 58. As can be appreciated, the transfer tube 54 communicates the lubricant l between the two opposing faces 56a and 56b.
Notably, at least some of the lubricant l moves away from the transfer tube 54 through a spray aperture 66. The lubricant l moving through the spray aperture 66 lubricates and cools at least some of the gears 26. The spray aperture 66 is axially spaced from the first face 56a and the second face 56b.
Referring to
The central section 70 of the example transfer tube 54 extends along an axis X. The central section 70 establishes a cylindrical bore 82. The example spray aperture 66 extends radially relative to the axis X from the bore 82 to an outer surface 86 of the central section 70.
In this example, the spray aperture 66 is configured to communicate the lubricant l to a meshing location between a first gear 90 and a second gear 94. The lubricant cools and lubricates the meshing location between the gears 90 and 94. The gear 94 of the gearbox 22 rotates about an axis A. The axis X of the bore 82 is parallel to the axis A in this example, and the spray aperture 66 is perpendicular to the axis X.
In other examples, the locations, sizes, and quantity of the spray aperture 66 are varied based on the lubrication requirements. Also, although described as a “spray” aperture, the spray aperture 66 is not limited to spraying lubricant l. For example, the spray aperture may allow the lubricant l to drip onto the meshing location or some other location.
The first end portion 74 and the second end portion 78 of the transfer tube 54 are both cylindrical in this example. The first end portion 74 establishes an axis X1, and the second end portion 78 establishes an axis X2. Notably, the axis X1 of the example first end portion 74 is the same as the axis X of the bore 82. That is, the first end portion 74 and the central section 70 are coaxial. By contrast, the axis X2 of the example second end portion 78 is offset from the axis X of the bore 82 and the axis X1 of the first end portion 74.
The positions of the first end portion 74 and the second end portion 78 relative to the central section 70 (including the axial positions) may be adjusted depending on the geometry of the gearbox 22 and the gears 26. In this example, the second end portion 78 and the bore 82 are axially offset to facilitate positioning the central section 70, and specifically the spray aperture 66 of the central section 70, near the meshing location while providing room to secure the second end portion 78. The offset functions as a clocking feature to circumferentially orient the central section 70. In another example, another clocking feature is used, such as a raised area of the second end portion 78 received within a notch. The raised area is only received in the notch when the central section 70 is circumferentially aligned to direct spray from the spray aperture 66 in a desired area.
The first end portion 74 is configured to be received within a recess 98 that is established within the first face 56a of the gearbox housing. An O-ring 106 seals the radially outer interface between the recess 98 and the first end. The lubricant l moves from the first conduit portion 50 into the first end portion 74. The lubricant l then moves through the central section 70. Notably, the first conduit section 50 is not coaxial with the axis X1 or the axis X, which may facilitate positioning the first end portion 74 in an area that avoids the gears 26 and other components. The first end portion 74 has a cup-shaped cross-sectional profile in this example (
The second end portion 78 is configured to be received within a recess 108 established within a cover 110 of the gearbox 22. The second end portion 78 includes an O-ring 114 to seal the radially outer interface between the second end portion 78 and the cover 110. Lubricant l communicates from the bore 82 to a cavity established within the second end portion 78 through the cover 110 to the second conduit portion 58.
Features of the disclosed example include a transfer tube that both transfers lubricant through a gearbox and communicates lubricant directly to areas of the gearbox requiring lubrication.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.
This invention was made with government support under Contract No. N00019-06-C-0081, and Subcontract No. 4500019224, awarded by the United States Navy. The Government has certain rights in this invention.
