Abstract:
A gas turbine engine includes a structural oil baffle housing which at least partially supports a set of intermediate gears.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to a gas turbine engine and, more particularly, to a geared architecture therefor. 
         [0002]    Epicyclic gear systems with planetary or star gearboxes may be used in gas turbine engines for their compact designs and efficient high gear reduction capabilities. Planetary and star gearboxes generally include three gear train elements: a central sun gear, an outer ring gear with internal gear teeth, and a plurality of planet gears supported by a planet carrier between and in meshed engagement with both the sun gear and the ring gear. The gear train elements share a common longitudinal central axis, about which at least two rotate. 
         [0003]    In gas turbine engine architectures where speed reduction transmission is required, the central sun gear generally receives rotary input from the powerplant, the outer ring gear is stationary and the planet gear carrier rotates in the same direction as the sun gear to provide torque output at a reduced rotational speed. In star gear trains, the planet carrier is held stationary and the output shaft is driven by the ring gear in a direction opposite that of the sun gear. 
         [0004]    During flight, lightweight structural engine case assemblies may deflect upon aero and maneuver loads that may cause transverse deflection commonly known as backbone bending. This deflection may cause the individual sun or planet gear&#39;s axis of rotation to lose parallelism with the central axis and may result in some misalignment at gear train journal bearings and at the gear teeth mesh. This misalignment may lead to efficiency losses and the potential for reduced life. 
       SUMMARY 
       [0005]    A gas turbine engine according to one disclosed non-limiting embodiment of the present disclosure includes a geared architecture with a multiple of intermediate gears, and a structural oil baffle housing that at least partially supports said set of intermediate gears. 
         [0006]    In a further embodiment of the foregoing embodiment, each of said multiple of intermediate gears is mounted to a respective flexible carrier post. In the alternative or additionally thereto, the foregoing embodiment includes a spherical joint mounted to each flexible carrier post. In the alternative or additionally thereto, in the foregoing embodiment structural oil baffle housing is mounted to a spherical joint mounted to each flexible carrier post. 
         [0007]    In a further embodiment of any of the foregoing embodiments, the gas turbine engine includes a rotationally fixed carrier, each of said multiple of intermediate gears mounted to a respective flexible carrier post which extends from said carrier. In the alternative or additionally thereto, the foregoing embodiment includes an oil manifold defined by said carrier. In the alternative or additionally thereto, in the foregoing embodiment the oil manifold includes a first oil circuit and a second oil circuit. In the alternative or additionally thereto, in the foregoing embodiment the first oil circuit communicates with each respective flexible carrier post. In the alternative or additionally thereto, in the foregoing embodiment the second oil circuit communicates with a multiple of oil nozzles. 
         [0008]    In a further embodiment of any of the foregoing embodiments, the gas turbine engine includes a rolling element bearing mounted between said structural oil baffle housing and each of said multiple of intermediate gears. In the alternative or additionally thereto, in the foregoing embodiment the structural oil baffle housing directs oil to said multiple of intermediate gears. In the alternative or additionally thereto, in the foregoing embodiment the multiple of oil nozzles are external to said structural oil baffle housing. 
         [0009]    In a further embodiment of any of the foregoing embodiments, the geared architecture includes a planetary gear system. 
         [0010]    In a further embodiment of any of the foregoing embodiments, the geared architecture includes a star gear system. 
         [0011]    A gas turbine engine according to another disclosed non-limiting embodiment of the present disclosure includes a carrier which defines an oil manifold with a first oil circuit and a second oil circuit, a multiple of flexible carrier post which extends from said carrier to support a respective intermediate gear, said first oil circuit communicates with each respective flexible carrier post, a structural oil baffle housing which at least partially supports said set of intermediate gears, and a multiple of oil nozzles in communication with said second oil circuit. 
         [0012]    In a further embodiment of the foregoing embodiment, the multiple of oil nozzles are each adjacent to a sun gear and one of said multiple of intermediate gears. In the alternative or additionally thereto, the foregoing embodiment includes a rolling element bearing mounted between said structural oil baffle housing and each of said multiple of intermediate gears. In the alternative or additionally thereto, in the foregoing embodiment the rolling element bearing is a ball bearing. In the alternative or additionally thereto, in the foregoing embodiment the rolling element bearing is a roller bearing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0014]      FIG. 1  is a schematic cross-sectional view of a geared architecture gas turbine engine; 
           [0015]      FIG. 2  is an expanded schematic view of the geared architecture; 
           [0016]      FIG. 3  is an schematic front view of a planetary gear system type epicyclic gear system of the geared architecture according to one disclosed non-limiting embodiment; 
           [0017]      FIG. 4  is an schematic front view of a star gear type epicyclic gear system of the geared architecture according to another disclosed non-limiting embodiment; 
           [0018]      FIG. 5  is an sectional view of the epicyclic gear system along line  5 - 5  in  FIG. 7 ; 
           [0019]      FIG. 6  is a sectional view of the epicyclic gear system along line  6 - 6  in  FIG. 7 ; and 
           [0020]      FIG. 7  is a schematic front view of an epicyclic gear system with a structural oil baffle housing according to one disclosed non-limiting embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      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 architectures such as a low-bypass turbofan may include an augmentor section (not shown) among other systems or features. Although schematically illustrated as a turbofan 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 to include but not limited to a three-spool (plus fan) engine wherein an intermediate spool includes an intermediate pressure compressor (IPC) between a low pressure compressor and a high pressure compressor with an intermediate pressure turbine (IPT) between a high pressure turbine and a low pressure turbine as well as other engine architectures such as turbojets, turboshafts, open rotors and industrial gas turbines. 
         [0022]    The fan section  22  drives air along a bypass flowpath and a core flowpath while the compressor section  24  drives air along the core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . The engine  20  generally includes a low spool  30  and a high spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine case assembly  36  via several bearing compartments  38 - 1 ,  38 - 2 ,  38 - 3 ,  38 - 4 . 
         [0023]    The low spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low-pressure compressor  44  (“LPC”) and a low-pressure turbine  46  (“LPT”). The inner shaft  40  drives the fan  42  through a geared architecture  48  to drive the fan  42  at a lower speed than the low spool  30 . The high spool  32  includes an outer shaft  50  that interconnects a high-pressure compressor  52  (“HPC”) and high-pressure turbine  54  (“HPT”). A combustor  56  is arranged between the HPC  52  and the HPT  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine central longitudinal axis A that is collinear with their longitudinal axes. 
         [0024]    Core airflow is compressed by the LPC  44  then the HPC  52 , mixed with the fuel and burned in the combustor  56 , then expanded over the HPT  54  and the LPT  46 . The HPT  54  and the LPT  46  drive the respective low spool  30  and high spool  32  in response to the expansion. 
         [0025]    In one example, the gas turbine engine  20  is a high-bypass geared architecture engine in which the bypass ratio is greater than about six (6:1). The geared architecture  48  can include an epicyclic gear system  58 , such as a planetary gear system ( FIG. 2 ), star gear system ( FIG. 3 ) or other system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3, and in another example is greater than about 2.5 with a gear system efficiency greater than approximately 98%. The geared turbofan enables operation of the low spool  30  at higher speeds which can increase the operational efficiency of the LPC  44  and LPT  46  and render increased pressure in a fewer number of stages. 
         [0026]    A pressure ratio associated with the LPT  46  is pressure measured prior to the inlet of the LPT  46  as related to the pressure at the outlet of the LPT  46  prior to an exhaust nozzle of the gas turbine engine  20 . In one non-limiting embodiment, the bypass ratio of the gas turbine engine  20  is greater than about ten (10:1), the fan diameter is significantly larger than that of the LPC  44 , and the LPT  46  has a pressure ratio that is greater than about five (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 disclosure is applicable to other gas turbine engines including direct drive turbofans. 
         [0027]    In one non-limiting embodiment, a significant amount of thrust is provided by the bypass flow due to the high bypass ratio. The fan section  22  of the gas turbine engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. This flight condition, with the gas turbine engine  20  at its best fuel consumption, is also known as bucket cruise Thrust Specific Fuel Consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust. 
         [0028]    Fan Pressure Ratio is the pressure ratio across a blade of the fan section  22  without a Fan Exit Guide Vane system. The low Fan Pressure Ratio according to one non-limiting embodiment of the example gas turbine engine  20  is less than 1.45. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of (“T”/518.7) 0.5  in which “T” represents the ambient temperature in degrees Rankine. The Low Corrected Fan Tip Speed according to one non-limiting embodiment of the example gas turbine engine  20  is less than about 1150 fps (351 m/s). 
         [0029]    With reference to  FIG. 4 , the epicyclic gear system  58  generally includes a sun gear  60  driven by a flexible input shaft  62  driven by the low spool  30 , a ring gear  64  connected to a ring gear output shaft  66  which connects the geared architecture  48  with the fan  42 , and a set of intermediate gears  68  in meshing engagement with the sun gear  60  and ring gear  64 . The flexible input shaft  62  transfers torque as well as facilitates the segregation of vibrations and other transients. 
         [0030]    With reference to  FIG. 5 , each intermediate gear  68  is rotationally mounted about a non-rotating flexible carrier post  70  that is respectively supported by a carrier  74  rotationally fixed to the engine case assembly  36 . In another, disclosed, non-limiting embodiment, the carrier may rotate while the ring gear is fixed ( FIG. 2 ). Each of the intermediate gears  68  is rotationally mounted on a respective spherical joint  76  mounted to each of the non-rotating flexible carrier posts  70 . The spherical joint  76  and non-rotating flexible carrier posts  70  allow the system to flex or “squirm” to reduce misalignment and minimize loads upon the intermediate gears  68  as well as permit the use of relatively large rolling element bearings  78  such as cylindrical roller or ball bearings. That is, the spherical joints  76  permit angular movement of the non-rotating flexible carrier posts  70  with minimal, if any, effect upon the intermediate gears  68 . 
         [0031]    The carrier  74  includes an oil manifold  80  that communicates oil through a first oil circuit  82  into each flexible carrier post  70  and a second oil circuit  84  through a multiple of oil nozzles  86  mounted to the carrier  74 . That is, the first oil circuit  82  communicates oil into each flexible carrier post  70  and thereby into the spherical joints  76 , then a structural oil baffle housing  88  and onto the rolling element bearings  78 . The second oil circuit  84  communicates oil as, for example, a spray directly onto the mesh between the sun gear  60  and the intermediate gears  68 . 
         [0032]    With reference to  FIG. 6 , the rolling element bearings  78  are mounted within the structural oil baffle housing  88 . The structural oil baffle housing  88  operates to support the intermediate gears  68  as well as an oil baffle to direct oil to the rolling element bearings  78 . The structural oil baffle housing  88  may include a first baffle portion  90  and a second baffle portion  92  which may be attached together, for example, with fasteners  94  and a tight overlap interface  96 . Various interfaces and baffle assembly methods may alternatively be provided. 
         [0033]    The structural oil baffle housing  88  is circumferentially segmented arcuate shape ( FIG. 7 ) about each intermediate gear  68  to permit gear mesh with the ring gear  64  and the sun gear  60  as well as entry and exit of oil. The structural oil baffle housing  88  is thereby shaped to direct oil without separate pressurization. 
         [0034]    Once communicated through the epicyclic gear system  58  the oil is radially expelled into an engine case  36 - 1  often referred to as a front center body of the engine case assembly  36 . To scavenge the oil rejected from the epicyclic gear system  58 , the engine case  36 - 1  includes an oil scavenge scoop  98  to capture oil. 
         [0035]    The structural oil baffle housing  88  reduces misalignment in the rolling element bearings  78 , which facilities usage of relatively higher capacity rolling element bearings  78  as compared to other bearing types. The structural oil baffle housing  88  also facilities direction of scavenge oil out to the ring gear  64  which facilitates an increase in efficiency from 98% to 99.5% efficiency. The difference in heat loss of 0.5% versus 2.0% drives a large amount of weight out of the oil cooling system which facilitates a size reduction of air-oil and fuel-oil coolers for engine thermal management to thereby facilitate a reduction in cost, weight and complexity of the engine  20 . 
         [0036]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.