Patent Publication Number: US-11028780-B2

Title: Hydraulic unit gear shrouds

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to gear shrouds, and more particularly to gear shrouds for gears integrated drive generators (IDGs). 
     2. Description of Related Art 
     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 Integrated Drive Generator (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. 
     SUMMARY OF THE INVENTION 
     A gear shroud arrangement includes a plate defining an aperture therethrough. A riser tube has a first end and an opposed second end. The first end of the riser tube is connected to the plate and is aligned with the aperture. A mounting flange extends from the second end of the riser tube. A shroud member extends from the plate in a direction opposite the riser tube. 
     The shroud member can include a first shroud segment circumferentially crossing a 12 o&#39;clock position on the plate as viewed looking toward the mounting flange, a second shroud segment circumferentially between the 12 o&#39;clock position and a 3 o&#39;clock position relative to the 12 o&#39;clock position, and a third shroud segment circumferentially between the 3 o&#39;clock position and a 6 o&#39;clock position relative to the 12 o&#39;clock position. The second and third shroud segments can be convex relative to the riser tube, and a concave web can connect between the second and third shroud segments. The concave web can define a notch therein. 
     The plate can define a registration feature for registering the plate with an IDG housing, wherein the registration feature includes a radiused section extending from a 6 o&#39;clock position to a 9 o&#39;clock position relative to the 12 o&#39;clock position. The registration feature can include a first flat land extending tangent to the radiused section from the 9 o&#39;clock position, terminating in an end that is perpendicular to the first flat land. The registration feature can include a second flat land extending tangent to the radiused section from the 6 o&#39;clock position, terminating at an end that is perpendicular to the second flat land. 
     An IDG housing can be included wherein the registration feature is engaged to an outer housing wall of the IDG housing. The mounting flange can define a plurality of fastener apertures therethrough. A hydraulic transmission unit can be mounted to the mounting flange by fasteners engaged in the fastener apertures. The hydraulic transmission unit can be a first hydraulic transmission unit, and an opposed gear shroud for a second hydraulic transmission unit can extend parallel to the first hydraulic transmission unit. The plate can define a concavity between the 12 o&#39;clock position and the 3 o&#39;clock position for accommodating a differential gear meshing with hydraulics transmission gear shrouded by the shroud member. The opposed gear shroud can engage a concave web in the plate. The riser tube can define an aperture therethrough extending in a circumferential portion of the riser tube from a position between an 11 o&#39;clock position and the 12 o&#39;clock position, and a position between 2 o&#39;clock and 3 o&#39;clock relative to the 12 o&#39;clock position. A differential shroud can extend within the aperture. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF 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: 
         FIG. 1  is a perspective view of an exemplary embodiment of a gear shroud constructed in accordance with the present disclosure, showing the plate with the riser tube and shroud member extending therefrom; 
         FIG. 2  is a plan view of the gear shroud of  FIG. 1 , showing the registration feature; 
         FIG. 3  is a cross-sectional plan view of a portion of the gear shroud of  FIG. 2 , showing the aperture through the riser tube; 
         FIG. 4  is a perspective view of the gear shroud of  FIG. 1 , showing the registration feature engaged with the outer wall of an integrated drive generator (IDG) housing; 
         FIG. 5  is a perspective view of the gear shroud arrangement of  FIG. 4 , showing two hydraulic transmission units and a differential unit engaged in the IDG housing; and 
         FIG. 6  is a perspective view of the IDG housing of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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  FIG. 1  and is designated generally by reference character  100 . Other embodiments of gear shrouds in accordance with the disclosure, or aspects thereof, are provided in  FIGS. 2-6 , as will be described. The systems and methods described herein can be used to shroud gears in IDGs to reduce the amount of oil churning, which improves IDG efficiency and scavenge pump performance, thus improving the IDG oil servicing range. 
     A gear shroud arrangement  100  includes a plate  102  defining an aperture  104  therethrough. A riser tube  106  has a first end  108  and an opposed second end  110 . The first end  108  of the riser tube is connected to the plate  102  and is aligned with the aperture  104  along the axis A. A mounting flange  112  extends from the second end  110  of the riser tube  106 . A shroud member  114  extends from the plate  102  in a direction opposite the riser tube  106 , i.e. the riser tube  106  extends upwards as oriented in  FIG. 1 , and the shroud member  114  extends downwards. The shroud member  114  includes a first shroud segment  116 , a second shroud segment  118 , and a third shroud segment  120 . 
     With reference now to  FIG. 2 , the first shroud segment  116  circumferentially crosses a 12 o&#39;clock position on the plate  102  as viewed looking toward the mounting flange  112 . The second shroud segment  118  is located circumferentially between the 12 o&#39;clock position and a 3 o&#39;clock position relative to the 12 o&#39;clock position. The third shroud segment  120  is located circumferentially between the 3 o&#39;clock position and a 6 o&#39;clock position relative to the 12 o&#39;clock position. The second and third shroud segments  118  and  120  are convex relative to the riser tube  106 . A concave web  122  connects between the second and third shroud segments  118  and  120 . The concave web  122  defines a notch  124  therein, as shown in  FIG. 1 . 
     The plate  102  defines a registration feature  126  for registering the plate  102  with an idg housing. The registration feature  126  includes a radiused section  128  extending from the 6 o&#39;clock position to a 9 o&#39;clock position relative to the 12 o&#39;clock position. The registration feature  126  includes a first flat land  130  extending tangent to the radiused section  128  from the 9 o&#39;clock position, terminating in an end  132  that is perpendicular to the first flat land  130 . The registration feature  126  includes a second flat land  134  extending tangent to the radiused section  128  from the 6 o&#39;clock position, terminating at an end  135  that is perpendicular to the second flat land  134 . 
     An IDG housing  136  is included wherein the registration feature  126  is engaged to an outer housing wall  138  of the IDG housing  136 . The mounting flange  112  defines a plurality of fastener apertures  140  therethrough. A hydraulic transmission unit  142 , shown in  FIG. 5 , is mounted to the mounting flange  112  by fasteners  144  engaged in the fastener apertures  140 . An opposed gear shroud  146 , shown in  FIG. 4 , is included for a second hydraulic transmission unit  148 , shown in  FIG. 5 , which extends parallel to the first hydraulic transmission unit  142 . The plate  102  defines a concavity  150 , identified in  FIG. 2 , between the 12 o&#39;clock position and the 3 o&#39;clock position for accommodating a differential gear  152 , identified in  FIG. 4 , meshing with a hydraulics transmission gear  154  shrouded by the shroud member  114  shown in  FIG. 1 . The opposed gear shroud  146 , shown in  FIG. 4 , engages the concave web  122  in the plate  102  shown in  FIG. 1 . The riser tube  106 , shown in  FIG. 1 , defines an aperture  156  therethrough. As shown in  FIG. 3 , the aperture  156  extends in a circumferential portion of the riser tube  106  from a position between an 11 o&#39;clock position and the 12 o&#39;clock position, and a position between 2 o&#39;clock and 3 o&#39;clock relative to the 12 o&#39;clock position. As shown in  FIG. 4 , a portion  158  of a differential shroud  160  extends within the aperture  156 . As shown in  FIG. 6 , when fully assembled, the outer housing wall  138  of the IDG housing  136  surrounds the components shown in  FIGS. 4-5  and forms an IDG  162 . 
     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.