Abstract:
A turbofan engine includes a fan rotatable about an axis, a compressor section, a combustor in fluid communication with the compressor section, a turbine section in fluid communication with the combustor, and a fan drive gear system including a carrier for supporting a plurality of gears. A torque frame is attached to the carrier. A plurality of connectors extends between the carrier and torque frame for securing the torque frame to the carrier. A scupper captures lubricant during gear operation and directing lubricant into a space between at least one of the plurality of connectors and at least one of the torque frame and the carrier.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 61/869,883 filed on Aug. 26, 2013. 
    
    
     BACKGROUND 
     A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. 
     A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds. 
     A carrier is provided to support rotation of the gears within the gear assembly. The carrier is attached to a torque frame to accommodate torque loads on the gear assembly. A series of pins extending through both the torque frame and carrier provides the connection between the torque frame and carrier. The pins are the only sliding interface, other than the gears, within the gear assembly and can be a source of wear if not sufficiently lubricated. Pressurized lubricant is communicated through passages within the pins to provide lubricant to the contact interface. Providing passages to and through each of the pins complicates assembly and increases costs. Accordingly, it is desirable to design and develop alternate lubricant arrangements to reduce cost and maintain lubricant efficiencies. 
     SUMMARY 
     A turbofan engine according to an exemplary embodiment of this disclosure, among other possible things includes a fan rotatable about an axis, a compressor section, a combustor in fluid communication with the compressor section, a turbine section in fluid communication with the combustor, and a fan drive gear system including a carrier for supporting a plurality of gears. A torque frame is attached to the carrier. A plurality of connectors extends between the carrier and torque frame for securing the torque frame to the carrier. A scupper captures lubricant during gear operation and directing lubricant into a space between at least one of the plurality of connectors and at least one of the torque frame and the carrier. 
     In a further embodiment of any of the foregoing turbofan engines, the fan drive gear system includes a sun gear driving a plurality of intermediate gears supported by the carrier and ring gear circumscribing the plurality intermediate gears. The ring gear is fixed relative to rotation of the carrier and torque frame about an axis of rotation. 
     In a further embodiment of any of the foregoing turbofan engines, the carrier and torque frame are configured to rotate about an axis of rotation and generate centrifugal forces for driving exhaust lubricant through the space between each of the plurality of connectors and one of the carrier and torque frame. 
     In a further embodiment of any of the foregoing turbofan engines, the scupper is a portion of the torque frame. 
     In a further embodiment of any of the foregoing turbofan engines, the scupper is a portion of the carrier. 
     In a further embodiment of any of the foregoing turbofan engines, the scupper includes a scoop that directs lubricant into the space. 
     In a further embodiment of any of the foregoing turbofan engines, the fan drive gear system provides a speed reduction between the turbine section and the fan section of greater than about 2.3. 
     In a further embodiment of any of the foregoing turbofan engines, the turbofan engine is a high bypass geared aircraft engine having a bypass ratio of greater than about ten (10). 
     In a further embodiment of any of the foregoing turbofan engines, the turbofan engine includes a Fan Pressure Ratio of less than about 1.45. 
     In a further embodiment of any of the foregoing turbofan engines, the turbine section includes a fan drive turbine coupled to drive the fan through the fan drive gear system and a second turbine forward of the fan drive turbine and a ratio of a number of fan blades in the fan and a number of rotors in the fan drive turbine is between about 3.3 and about 8.6. 
     A fan drive gear system according to an exemplary embodiment of this disclosure, among other possible things includes a carrier for supporting a plurality of gears, a torque frame attached to the carrier, a plurality of connectors extending between the carrier and torque frame for securing the torque frame to the carrier, and a scupper for capturing lubricant during gear operation and directing lubricant into a space between the plurality of connectors and at least one of the torque frame and the carrier. 
     In a further embodiment of any of the foregoing fan drive gear systems, the scupper is a portion of the torque frame. 
     In a further embodiment of any of the foregoing fan drive gear systems, the plurality of connectors are each press fit at each distal end into the carrier and the space is defined between each connector and the torque frame. 
     In a further embodiment of any of the foregoing fan drive gear systems, the carrier includes at least one opening for communicating lubricant to the scupper. 
     In a further embodiment of any of the foregoing fan drive gear systems, the scupper is a portion of the carrier. 
     In a further embodiment of any of the foregoing fan drive gear systems, the plurality of connectors are press fit at each distal end into the torque frame and the space is defined between each connector and the carrier. 
     In a further embodiment of any of the foregoing fan drive gear systems, the scupper includes a scoop that directs lubricant into the space. 
     In a further embodiment of any of the foregoing fan drive gear systems, includes a sun gear driving a plurality of intermediate gears supported by the carrier and a ring gear circumscribing the plurality intermediate gears. The ring gear is fixed relative to rotation of the carrier and torque frame about an axis of rotation. 
     In a further embodiment of any of the foregoing fan drive gear systems, the carrier and torque frame are configured to rotate about an axis of rotation and generate centrifugal forces for driving exhaust lubricant through the space between each of the plurality of connectors and one of the carrier and torque frame. 
     A method of designing a fan drive gear system for a turbofan engine according to an exemplary embodiment of this disclosure, among other possible things includes configuring a torque frame for attachment to a carrier by way of a plurality of connectors, configuring a lubricant flow path such that rotation of the carrier and torque frame generate centrifugal forces in exhaust lubricant, configuring at least one of the carrier and the torque frame with scuppers for capturing at least a portion of lubricant exhausted from a plurality of gears, and configuring the scuppers to direct the captured lubricant into a space between the plurality of connectors and one of the torque frame and carrier. 
     In a further embodiment of any of the foregoing methods, the scuppers are defined on the torque frame and the press fit is between each of the plurality of connectors and the carrier. 
     In a further embodiment of any of the foregoing methods, the scuppers are defined on the carrier and the press fit is between each of the plurality of connectors and the torque frame. 
     In a further embodiment of any of the foregoing methods, includes defining an outlet from the space between the plurality of connectors for exhausting lubricant from the space. 
     In a further embodiment of any of the foregoing methods, configures a sun gear to drive the plurality of gears supported by the carrier and configuring a ring gear to circumscribe the plurality of gears such that the ring gear is fixed relative to rotation of the carrier and torque frame about an axis of rotation. 
     In a further embodiment of any of the foregoing methods, includes configuring the fan drive gear system to provide a speed reduction ratio greater than about 2.3:1. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an example gas turbine engine. 
         FIG. 2  is a schematic representation of an example fan drive gear system. 
         FIG. 3  is a schematic cross-sectional view of the example fan drive gear system. 
         FIG. 4  is an enlarged schematic view of an interface between example torque frame and carrier. 
         FIG. 5  is another schematic representation of another fan drive gear system. 
         FIG. 6  is a cross-sectional view of the example fan drive gear system shown in  FIG. 5 . 
         FIG. 7  is an enlarged cross-section of another interface between a carrier and torque frame. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an example gas turbine engine  20  that includes a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B while the compressor section  24  draws air in along a core flow path C where air is compressed and communicated to a combustor section  26 . In the combustor section  26 , air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section  28  where energy is extracted and utilized to drive the fan section  22  and the compressor section  24 . 
     Although the disclosed non-limiting embodiment depicts a two-spool turbofan gas turbine engine, 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; for example a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a high pressure compressor of the compressor section. 
     The example 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. 
     The low speed spool  30  generally includes an inner shaft  40  that connects a fan  42  and a low pressure (or first) compressor section  44  to a low pressure (or first) turbine section  46 . The inner shaft  40  drives the fan  42  through a speed change device, such as 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 (or second) compressor section  52  and a high pressure (or second) turbine section  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via the bearing systems  38  about the engine central longitudinal axis A. 
     A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . In one example, the high pressure turbine  54  includes at least two stages to provide a double stage high pressure turbine  54 . In another example, the high pressure turbine  54  includes only a single stage. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine. 
     The example low pressure turbine  46  has a pressure ratio that is greater than about 5. The pressure ratio of the example low pressure turbine  46  is measured prior to an inlet of the low pressure turbine  46  as related to the pressure measured at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. 
     A mid-turbine frame  58  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  58  further supports bearing systems  38  in the turbine section  28  as well as setting airflow entering the low pressure turbine  46 . 
     Airflow through the core airflow path C is compressed by the low pressure compressor  44  then by the high pressure compressor  52  mixed with fuel and ignited in the combustor  56  to produce high speed exhaust gases that are then expanded through the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  58  includes vanes  60 , which are in the core airflow path and function as an inlet guide vane for the low pressure turbine  46 . Utilizing the vane  60  of the mid-turbine frame  58  as the inlet guide vane for low pressure turbine  46  decreases the length of the low pressure turbine  46  without increasing the axial length of the mid-turbine frame  58 . Reducing or eliminating the number of vanes in the low pressure turbine  46  shortens the axial length of the turbine section  28 . Thus, the compactness of the gas turbine engine  20  is increased and a higher power density may be achieved. 
     The disclosed gas turbine engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the gas turbine engine  20  includes a bypass ratio greater than about six (6), with an example embodiment being greater than about ten (10). The example geared architecture  48  is an epicyclical gear train, such as a planetary gear system, with a gear reduction ratio of greater than about 2.3. 
     In one disclosed embodiment, the gas turbine engine  20  includes a bypass ratio greater than about ten (10:1) and the fan diameter is significantly larger than an outer diameter of the low pressure compressor  44 . It should be understood, however, that the above parameters are only exemplary of one embodiment of a gas turbine engine including a geared architecture and that the present disclosure is applicable to other gas turbine engines. 
     A significant amount of thrust is provided by airflow through the bypass flow path 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 pound-mass (lbm) of fuel per hour being burned divided by pound-force (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 1.50. In another non-limiting embodiment the low fan pressure ratio 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. 
     The example gas turbine engine includes the fan  42  that comprises in one non-limiting embodiment less than about twenty-six (26) fan blades. In another non-limiting embodiment, the fan section  22  includes less than about twenty (20) fan blades. Moreover, in one disclosed embodiment the low pressure turbine  46  includes no more than about six (6) turbine rotors schematically indicated at  34 . In another non-limiting example embodiment the low pressure turbine  46  includes about three (3) turbine rotors. A ratio between the number of fan blades  42  and the number of low pressure turbine rotors is between about 3.3 and about 8.6. The example low pressure turbine  46  provides the driving power to rotate the fan section  22  and therefore the relationship between the number of turbine rotors  34  in the low pressure turbine  46  and the number of blades  42  in the fan section  22  discloses an example gas turbine engine  20  with increased power transfer efficiency. 
     Referring to  FIG. 2 , with continued reference to  FIG. 1 , the example gas turbine engine  20  includes a fan drive gear system  62  that includes the geared architecture  48 . The fan drive gear system  62  drives a fan shaft  64  that, in turn, drives the fan blades  42  about the axis A. 
     The example geared architecture  48  gear arrangement is referred to as a planetary system and includes intermediate or planet gears  78  supported by a carrier  66 . The carrier  66  rotates to drive the fan shaft  64 . 
     Referring to  FIGS. 2 ,  3  and  4  with continued reference to  FIG. 1 , the example fan drive gear system  62  includes a carrier  66  that is secured to a torque frame  68  at a plurality of connection interfaces  74  spaced apart circumferentially. Each of the connection interfaces includes a connector  70 , which may, as shown, be in the form of a pin. 
     The carrier  66  supports rotation of the plurality of intermediate gears  78  that are arranged about a sun gear  76 . The sun gear  76  drives the intermediate or planet gears  78  that are supported within the carrier  66 . The intermediate gears  78 , in turn, are circumscribed by a ring gear  80  (schematically shown in  FIGS. 1 and 2 ). In this example of a fan drive gear system  62 , the ring gear  80  is fixed to a static structure  36  of the gas turbine engine  20  ( FIG. 1 ). The carrier  66  and torque frame  68  rotate about the axis A in response to rotation of the sun gear  76 . In this example, the carrier  66  and torque frame  68  rotate in the direction indicated by the arrow R about the engine axis A in a direction common with rotation of the sun gear  76 . 
     The gears  78  are driven by the sun gear  76  and are fed with a lubricant flow that is communicated to the interface between the sun gear  76  and the intermediate gears  78 . Lubricant that has been flowed through the interface between meshed gears is exhausted outwardly and is typically received within a gutter or other lubricant capture arrangement. In this example, a portion of that exhausted lubricant indicated by arrows  84  is captured within an accumulator  82  defined within the carrier  66 . The accumulator  82  captures some of the exhausted lubricant  84  and communicates that lubricant to the interface  74 . 
     The interface  74  between the torque frame  68  and the carrier  66  is provided through the pin  70 . Ends  88  of the pin  70  are attached to the carrier by corresponding press fits  90 . The press fit  90  of the pin  70  secures the torque frame  68  to the carrier  66 . The example press fit  90  is an interference fit that provides a desired fit to maintain the ends  88  of the pin  70  within the carrier  66 . 
     The fit between the torque frame  68  and the pin  70  is a running or clearance fit and includes a space  94 . Lubricant is directed through the space  94  to reduce wear and flush out debris. 
     Rotation of the fan drive gear system  62  generates a centrifugal force that drives the lubricant  84  radially outward once exhausted from the meshing interface between the sun gear  76  and each of the plurality of the intermediate gears  78 . The lubricant  84  is captured and channeled towards the interfaces  74  defined between the torque frame  68  and the carrier  66 . 
     The interfaces  74  between the torque frame  68  and the carrier  66  are the only relative moving elements, other than the gear interface, within the fan drive gear system  62  and therefore may wear undesirably if not properly lubricated. 
     The example fan drive gear system  62  channels the exhausted lubricant  84  into the space  94  defined between each of the pins  70  and the torque frame  68 . 
     The exhausted lubricant  84  is channeled first through the accumulator  82  defined in the carrier  66  towards the interfaces  74  by the centrifugal forces generated by rotation of the carrier  66 . The lubricant  84  is further directed by scuppers  72  defined on the torque frame  68 . The scuppers  72  take the lubricant  84  and direct it into the space  94  between the pin  70  and the torque frame  68 . 
     In this example, the scuppers  72  are funnel or scoop shaped features that are formed directly into the torque frame  68  and direct the radially discharged exhaust lubricant  84  towards into the space  94 . The space  94  is open at each end such that lubricant  84  flow enters and is exhausted from the space  94  to provide a continued replenishment of lubricant between the pin  70  and the torque frame  68 . 
     Referring to  FIGS. 5 ,  6  and  7  with continued reference to  FIG. 1 , another fan drive gear system  65  includes a carrier  100  that is attached to a torque frame  98  through interfaces  75 . The interfaces  75  include a connector  70  (which may, as shown, be in the form of a pin) secured with a press fit to the torque frame  98  and a running fit with the carrier  100 . The carrier  100  includes a lubricant scupper  104  that channels exhausted lubricant  84  into a space  106  defined between the pin  70  and the carrier  100 . In this instance, the scupper  104  comprises a passage  102  that directs lubricant  84  into the space  106  between the pin  70  and the carrier  100 . 
     In operation, lubricant exhausted from the interface between the sun gear  76  and the intermediate gears  78  is flung radially outward towards the interfaces  75  between the carrier  100  and the torque frame  98 . Some of the exhausted lubricant  84  is simply flung radially outward into gutter and other structures (not shown) that are provided to accumulate the exhausted lubricant  84 . 
     A portion of lubricant  84  is captured by the accumulators  82  defined within the carrier  100  and channeled toward each of the interfaces  75 . In this example, there are five interfaces  75  circumferentially spaced evenly about the periphery of the carrier  100  and the torque frame  98 . In this example, the scupper  104  defines the passage  102  that captures the radially outward flung lubricant  84  and directs that lubricant into the space  106  between the pin  70  and the carrier  100 . 
     As appreciated in this example, a running fit is provided between the carrier  100  and the pin  70 . A press fit  96  is provided between the torque frame  98  and the pin  70 . Lubricant flows through the space  106  and is exhausted as is indicated by arrows  86  to ensure a continued replenishment of lubricant. The force and pressures required to drive lubricant into the space  106  and  94  is provided by the centrifugal forces generated by rotation of the carrier  100  and torque frame  98 . 
     Accordingly, the example interface configuration provides for the continued lubrication of the interface between the torque frame  98  and the carrier  100  without the use of pressurized lubricant flow provided by a pump. Moreover, because lubricant is communicated through scuppers and other oil scavenging configurations arranged on either the torque frame  98  or the carrier  100 , complex and difficult to manufacture passages through the pins  70  are not required. Accordingly, the example configuration provides for the lubrication of the interfaces without complex machining by utilizing the centrifugal forces generated during operation. 
     Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.