Abstract:
A turbine is operably connected to drive a compressor, and to drive a fan through a gear drive. A number of intermediate gears connecting an output shaft of the turbine to a fan drive shaft for the fan. An oil channel collects oil thrown outwardly of the gear drive. A bearing support mounts bearings supporting the fan drive shaft. The oil channel and the bearing support each include mating faces that are bolted together by a plurality of bolts. The bolts extend through oil channel holes in the mating face of the oil channel. The oil channel holes have one dimension which closely receives the bolts and another dimension which is larger than an outer diameter of the extending portion of the bolts, such that the bolts may adjust radially within the oil channel holes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates to mounting an oil channel which collects oil from a fan drive gear in a gas turbine engine. 
         [0002]    Gas turbine engines are known and typically include a fan delivering air into a bypass duct as propulsion air and into a compressor section. The compressor section may include a pair of compressor rotors, with one operating at a lower pressure than a second. The air is compressed serially across the two compressor rotors and delivered into a combustion section. The air is mixed with fuel and ignited, and products of the combustion pass downstream over at least two turbine rotors, with one turbine rotor operating at a higher pressure than the other. The lower pressure turbine rotor drives the lower pressure compressor and may drive the fan. Historically, the lower pressure turbine drove the lower pressure compressor and the fan at a single speed. 
         [0003]    More recently, a gear drive has been provided between the fan and the lower pressure turbine. This allows the fan to rotate at a slower speed than the lower pressure compressor, which has many benefits. 
         [0004]    The gear drive is a complex device involving any number of interrelated systems. Oil is critical for the gear drive and there is an oil supply system. 
         [0005]    An oil collection component, known as an oil channel, is positioned radially outwardly of a ring gear that is part of the fan drive gear. The oil channel has been mounted to a bearing support housing. The bearing support housing is formed of an appropriate titanium alloy. It is desirable to form the oil channel of a lighter weight material and aluminium has been utilized. Differences in thermal expansion between the aluminium and the titanium alloy have raised challenges at a mount interface. 
       SUMMARY OF THE INVENTION 
       [0006]    In a featured embodiment, a gas turbine engine has a propuslor that includes a fan and a fan drive gear architecture for rotating about a central axis. The fan drive gear architecture includes a number of intermediate gears connecting an output shaft of a fan drive turbine to a fan drive shaft for the fan. An oil channel collects oil thrown radially outwardly of the fan drive gear architecture. A bearing support mounts bearings that support the fan drive shaft. The oil channel and bearing support are fixed together by elongated connecting members that have respective shafts extending through slots in the oil channel. A slot width sized to closely receive the connecting member shafts and a slot length is relatively larger. The connecting members may adjust in a radial direction within the slots to allow the oil channel and bearing support to expand at different rates in the radial direction. 
         [0007]    In another embodiment according to the previous embodiment, the oil channel holes are generally racetrack shape with two generally parallel side surfaces defining the width extending outwardly in a generally radial direction and curved ends at radial ends of the oil channel holes defining the length. 
         [0008]    In another embodiment according to any of the previous embodiments, an insert is inserted into spaced locations in the oil channel and said insert defining said slots. 
         [0009]    In another embodiment according to any of the previous embodiments, a gasket is positioned intermediate the bearing support and oil channel. 
         [0010]    In another embodiment according to any of the previous embodiments, the oil channel has a pair of surfaces for receiving oil thrown radially outwardly of a ring gear in the gear drive. 
         [0011]    In another embodiment according to any of the previous embodiments, the surfaces are spaced on opposed sides of a centerline of the ring gear. 
         [0012]    In another embodiment according to any of the previous embodiments, the slots are formed in an insert force fit into spaced locations on the oil channel. 
         [0013]    In another embodiment according to any of the previous embodiments, the inserts are formed of a material that is relatively hard compared to a material forming the oil channel. 
         [0014]    In another embodiment according to any of the previous embodiments, both of the inserts and connecting members are formed of an appropriate steel. 
         [0015]    In another embodiment according to any of the previous embodiments, bearing support is formed of a titanium alloy and said oil channel is formed of aluminum. 
         [0016]    In another embodiment according to any of the previous embodiments, a Belleville spring washer sits between a head of the connecting members and the oil channel, with the Belleville washer urging the oil channel toward the bearing support to compensate for any wear during operation of the gas turbine engine. 
         [0017]    In another embodiment according to any of the previous embodiments, the connecting members are bolts. 
         [0018]    In another featured embodiment, a gas turbine engine has a propuslor that includes a fan and a fan drive gear architecture for rotating about a center axis. The fan drive gear architecture includes a number of intermediate gears connecting an output shaft of the turbine to a fan drive shaft for the fan. An oil channel collects oil thrown radially outwardly of the fan drive gear architecture. A bearing support mounts bearings, or the bearing supporting the fan drive shaft. The oil channel and bearing support are fixed together by elongated connecting members that have respective shafts extending through slots in the oil channel. The slots are generally racetrack shape with two generally parallel side surfaces extending outwardly in a generally radial direction and curved ends at radial ends of the slots. An insert is inserted into spaced locations in the oil channel. The insert defines the slots. A gasket is positioned intermediate the bearing support and oil channel. The oil channel has a pair of surfaces for receiving oil thrown radially outwardly of a ring gear in the gear drive. The surfaces are spaced on opposed sides of a centerline of the ring gear. The bearing support is formed of a titanium alloy and the oil channel is formed of aluminum. A slot width is defined perpendicular to the generally parallel side surfaces. A slot length is defined between the radial ends, and the slot width is sized to closely receive the shafts of the connecting members. The slot length is relatively larger whereby the connecting members may adjust in a radial direction within the slots to allow the oil channel and bearing support to expand at different rates in a radial direction. 
         [0019]    In another embodiment according to the previous embodiment, the insert is force fit into spaced locations in the oil channel. 
         [0020]    In another embodiment according to any of the previous embodiments, the inserts are formed of a material that is relatively hard compared to a material forming the oil channel. 
         [0021]    In another embodiment according to any of the previous embodiments, both the inserts and bolts are formed of an appropriate steel. 
         [0022]    In another embodiment according to any of the previous embodiments, a Belleville spring washer sits between a head of the bolts and oil channel, with the Belleville washer urging the oil channel toward the bearing support to compensate for any wear during operation of the gas turbine engine. 
         [0023]    These and other features may be best understood from the following drawings and specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  schematically shows a gas turbine engine. 
           [0025]      FIG. 2  is a cross-sectional view through a portion of a gas turbine engine. 
           [0026]      FIG. 3  is an exploded view of several components that are illustrated in  FIG. 2 . 
           [0027]      FIG. 4  is an enlarged prospective view of a portion of  FIG. 2  cross-section. 
           [0028]      FIG. 5  shows a detail of guided movement. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B in a bypass duct defined within a nacelle  15 , while the compressor section  24  drives air along a core flow path C for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
         [0030]    The engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided. 
         [0031]    The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor  44  and a low pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through a geared architecture  48  to drive the fan  42  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  50  that interconnects a high pressure compressor  52  and high pressure turbine  54 . A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . A mid-turbine frame  57  of the engine static structure  36  is arranged generally between the high pressure turbine  54  and the low pressure turbine  46 . The mid-turbine frame  57  further supports bearing systems  38  in the turbine section  28 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via bearing systems  38  about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
         [0032]    The core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  57  includes airfoils  59  which are in the core airflow path. The turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. 
         [0033]    The engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the engine  20  bypass ratio is greater than about six (6), with an example embodiment being greater than ten (10), the geared architecture 48 is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3 and the low pressure turbine 46 has a pressure ratio that is greater than about 5. In one disclosed embodiment, the engine  20  bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor  44 , and the low pressure turbine  46  has a pressure ratio that is greater than about 5:1. Low pressure turbine  46  pressure ratio is pressure measured prior to inlet of low pressure turbine  46  as related to the pressure at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. The geared architecture  48  may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.5:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including direct drive turbofans. 
         [0034]    A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section  22  of the engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft, with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(518.7° R)] 0.5 . The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 ft/second. 
         [0035]      FIG. 2  shows a portion of a gear drive  48  for driving the fan  42 . As shown, a pair of bearings  92  and  194  are supported in a bearing support  90 . The bearings  92  and  194  support a shaft  84  which is downstream of the gear drive  48 , and which connects the gear drive  48  to the fan  42 . 
         [0036]    The shaft  84  is driven by an element  82  driven by a ring gear  80 . The ring gear  80  is driven by planet gears  86  that are, in turn, driven by a sun gear  88 . An input  89  drives the sun gear  88 . It may also be that a star gear configuration can be used as a gear drive and benefit from the teaching of this application. 
         [0037]    An oil collector, known as an oil channel  94 , is positioned radially outwardly of the ring gear  80 . As shown, there are surfaces  96  and  98  on opposed sides of a center plane C of the ring gear  80 , which serve to capture and collect oil which is thrown outwardly of the gear drive  48 . The oil channel  94  includes a surface or face  100  which is connected to a surface or face  110  of the bearing support  90 . A Teflon® gasket  108  is positioned between the surfaces  100  and  110 . Bolts  106  are shown securing the surface  100  to the surface  110 . 
         [0038]      FIG. 3  is an exploded view showing the bearing support  90  having surface  110 . The gasket  108  is positioned intermediate this surface  110  and a surface  100  on the oil channel  94 . 
         [0039]    The oil channel  94  operates in a known manner to collect the oil and drain the oil from a vertically lower space  200 , shown schematically in  FIG. 3 . 
         [0040]    As shown in  FIG. 4 , the face  100  in the oil channel  94  is spaced from the face  110  of the bearing support by the gasket  108 . 
         [0041]    A bolt  106  has a threaded body  123  received on threads  125  within a bore  112  in the bearing support  90 . The threads  125  may be formed on a separate component inserted into bore  12 . A steel insert  116  is pressed into an opening  114  in the oil channel  94 . It should be understood that the structure about to be described in  FIG. 4  is at a number of locations where the bolts  106  are utilized to secure the oil channel  94  to the bearing support  90 , and at both circumferentially spaced locations and at the two radial positions shown in  FIG. 2 . The steel insert  116  is separated from a head  122  of the bolt  106  by a Belleville washer  120 . As shown, there is a space  118  between an outer periphery of the extending portion (shaft)  123  of the bolt  106 , and an inner periphery of a hole or opening  130  in the insert  116 . While a bolt is disclosed, other elongated connecting members may be used. 
         [0042]    As shown in  FIG. 5 , one opening, or slot,  130 A is generally racetrack shaped or has two curves  132 A at the end of elongated straight portions  129 A and  131 A. That is, the opening is generally rectangular with curves formed by rounded corners. The curves  132 A are spaced from each other by a greater distance than a diameter of the extending portion  123  of the bolt  106 . This provides the clearance  118  as mentioned above. As shown in  FIG. 5 , two of the circumferentially spaced inserts  116 A and  116 B are shown. The elongated straight portions  129 A and  131 A are generally parallel to each other, and spaced by equidistance from a first radial line R 1  extending from a central line A of the engine. A second insert  116 B is also shown having elongated straight portions  129 B and  131 B which are also parallel to each other, and which are spaced equidistance from a radial line R 2 . The elongated straight portions  131 A and  129 A are not parallel to the elongated straight portions  131 B and  129 B. This allows adjustment in a radial direction across the circumference of the oil channel  4 . The slots  130 A/B could be defined to have a width measured perpendicular to a radial line, and perpendicular to elongated straight portions  129 A and  131 A. The width closely receives the extending portion  123 . Further, a length can be described between the curves  132 A, and the length is relatively larger than an outer periphery of the extending portion E 123 . 
         [0043]    Now, during operation, the engine  20  and the gear drive  48  will become hot. The oil channel  94  will expand at a distinct rate than the bearing support  90 . When this growth is in a radial direction, the extending portion  123  of the bolt may move between the ends  132 , such that the oil channel  94  can move radially relative to the bearing support  90  as the engine heats and cools. The sides  129  and  131  will guide this movement to be generally purely radial. This radial motion ensures the oil channel  94  remains concentric with the fan drive gear system thus ensuring efficient removal of oil, and preventing local contact with the fan drive gear system and the oil channel  94 . 
         [0044]    As the faces  110  and  100  move relative to each other, the gasket  108  prevents undue wear on either surface. 
         [0045]    The inserts  116  may be formed of a material which is relatively hard compared to a material forming the oil channel  94 . The inserts  116  and the bolts may be formed of an appropriate steel. 
         [0046]    The Belleville washer  120  is initially compressed. If there is wear, the Belleville washer  120  will expand to ensure that there is still a clamping load properly clamping the oil channel  94  to the bearing support  90 . 
         [0047]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.