Patent Application
20200292056
Generators are connected to gas turbine engines so that aircraft can generate on board electricity. In order to produce useful power, generators need to be driven at a substantially constant speed. To drive a generator at a constant speed using a gas turbine engine that runs at very different speeds at different stages in a flight, a constant speed drive (CSD) can be connected between the gas turbine engine and the generator. A CSD is a type of transmission that reduces the range of speed at its input to a much narrower range of speed at its output to provide a nearly constant output speed over a range of input speeds. A CSD and generator can be integrated together into a single unit called an IDG.
The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved CSDs and IDGs. This disclosure provides a solution for this need.
A gear shroud arrangement includes a mounting plate defining an aperture therethrough. A first cylindrical shroud is included having a first end and an opposed second end, wherein the first end of the first shroud is connected to an outer periphery of the mounting plate and is aligned with the aperture. A backing plate is mounted to the second end of the first shroud. A second cylindrical shroud extends from the backing plate in a direction opposite the first shroud.
The first shroud can extend clockwise from a position between a 12 o'clock position and a 1 o'clock position as viewed toward the mounting plate and a 6 o'clock position relative to the 12 o'clock position. The second shroud can extend clockwise from the 12 o'clock position as viewed toward the mounting plate and a position between a 3 o'clock position and a 4 o'clock position relative to the 12 o'clock position. The mounting plate can define an off-center aperture therethrough between a 3 o'clock position and a 6 o'clock position relative to the 12 o'clock position. The off-center aperture can have a generally lunate shape with a nose extending toward a center axis of the mounting plate from the generally lunate shape. The mounting plate can include a riser tube extending about the aperture and extending in a direction away from the backing plate.
The second shroud can include a first step and a second step extending further from the backing plate than the first step. The first and second steps can meet at a position between the 12 o'clock position and a 1 o'clock position relative to the 12 o'clock position. The second step can extend clock-wise from the first step. A mounting flange with a fastener aperture can extend from the second shroud where the first and second steps meet.
An IDG housing can be included, wherein the mounting flange is engaged to an outer housing wall of the IDG housing. The mounting plate can define a plurality of fastener apertures therethrough. A differential unit can be mounted to the mounting plate by fasteners engaged in the fastener apertures. The mounting plate, first shroud, second shroud, and backing plate can form a first gear shroud portion and an opposed gear shroud portion can be engaged with the first gear shroud portion and with the differential unit to form a complete gear shroud for the differential unit. Each of the mounting plate and backing plate of each of the gear shroud portions can include a concave notch proximate the 12 o'clock position.
These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.
So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:
Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a gear shroud arrangement in accordance with the disclosure is shown in
The gear shroud arrangement 100 includes a mounting plate 102 defining a semi-circular aperture 104 therethrough. A first cylindrical shroud 106 is included having a first end 108 and an opposed second end 110. The first end 108 of the first shroud 106 is connected to an outer periphery of the mounting plate 102 and is aligned with the aperture 104 relative to the axis A defined by the mounting plate 102. A backing plate 112 is mounted to the second end 110 of the first shroud 106. A second cylindrical shroud 114 extends from the backing plate 112 in a direction opposite the first shroud 106, i.e., the first shroud 106 extends upward from the backing plate 112 as oriented in
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The methods and systems of the present disclosure, as described above and shown in the drawings, provide for gear shrouds with superior properties including reducing the amount of oil churning, which improves IDG efficiency and scavenge pump performance, thus improving the IDG oil servicing range. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.
