Patent Publication Number: US-2022235823-A1

Title: Seal runner with deflector and catcher for gas turbine engine

Description:
STATEMENT REGARDING GOVERNMENT SUPPORT 
     This invention was made with Government support under FA8626-16-C-2139 awarded by the United States Air Force. The Government has certain rights in this invention. 
    
    
     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 combustor 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. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines. 
     A gas turbine engine also includes bearings that support rotatable shafts. The bearings require lubricant. Various seals near the rotating shafts contain oil within bearing compartments, which include bearings and seals. During operation of the engine, the seals maintain compartment pressures and keep lubricating oil inside the various compartments. 
     SUMMARY 
     A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a bearing compartment, a seal runner, a seal configured to cooperate with the seal runner to seal the bearing compartment, and a catcher in contact with the seal runner to minimize deflection of the seal runner. 
     In a further non-limiting embodiment of the foregoing engine, the seal runner includes a tab in contact with the catcher. 
     In a further non-limiting embodiment of any of the foregoing engines, the seal runner includes an axially-extending portion configured to contact the seal, and the seal runner further includes a deflector projecting radially from an aft end of the axially-extending portion. 
     In a further non-limiting embodiment of any of the foregoing engines, the deflector is integrally formed with the seal runner. 
     In a further non-limiting embodiment of any of the foregoing engines, the tab is arranged adjacent the intersection of the axially-extending portion and the deflector. 
     In a further non-limiting embodiment of any of the foregoing engines, the tab is spaced radially-inward of the axially-extending portion. 
     In a further non-limiting embodiment of any of the foregoing engines, the engine includes a stack spacer arranged about a shaft of the gas turbine engine, and the catcher is integrally formed with the stack spacer. 
     In a further non-limiting embodiment of any of the foregoing engines, the catcher includes a first leg extending radially from the stack spacer and a second leg extending axially from a free end of the first leg such that the catcher is substantially L-shaped in cross-section. 
     In a further non-limiting embodiment of any of the foregoing engines, a radially inner surface of the second leg of the catcher is in contact with a radially outer surface of a tab of the seal runner. 
     In a further non-limiting embodiment of any of the foregoing engines, the first leg of the catcher includes at least one passageway configured to permit fluid to flow into the bearing compartment. 
     In a further non-limiting embodiment of any of the foregoing engines, the stack spacer includes at least one orifice configured to permit fluid to flow into a space between a radially inner surface of the seal runner and a radially outer surface of the stack spacer. 
     In a further non-limiting embodiment of any of the foregoing engines, the at least one orifice is configured to cause fluid to impinge upon the radially inner surface of the seal runner at a location opposite the interface between the seal and the seal runner. 
     In a further non-limiting embodiment of any of the foregoing engines, the stack spacer and seal runner are arranged such that, after fluid impinges on the radially inner surface of the seal runner, the fluid turns in an aft direction and flows toward the at least one passageway of the catcher, and ultimately through the at least one passageway of the catcher and into the bearing compartment. 
     In a further non-limiting embodiment of any of the foregoing engines, the shaft is rotatably supported by a plurality of bearings contained within the bearing compartment. 
     In a further non-limiting embodiment of any of the foregoing engines, the shaft is one of an inner shaft and an outer shaft of the gas turbine engine. 
     A method according to an exemplary aspect of the present disclosure includes, among other things, using a catcher to restrict deflection of a seal runner relative to a seal. The seal and seal runner are configured to seal a bearing compartment of a gas turbine engine. 
     In a further non-limiting embodiment of the foregoing method, the catcher is integrally formed with a stack spacer arranged relative to a shaft of the gas turbine engine. 
     In a further non-limiting embodiment of any of the foregoing methods, the seal runner includes a deflector integrally formed therewith and projecting radially from an axially-extending portion of the seal runner, and wherein the catcher contacts the seal runner adjacent the intersection of the deflector and the axially-extending portion. 
     In a further non-limiting embodiment of any of the foregoing methods, the method includes establishing a flow of fluid through an orifice in the stack spacer such that the flow of fluid impinges on a radially inner surface of the seal runner. 
     In a further non-limiting embodiment of any of the foregoing methods, the method includes turning the flow of fluid in an aft direction toward the catcher, and introducing the flow of fluid into the bearing compartment via a passageway in the catcher. 
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a gas turbine engine. 
         FIG. 2  illustrates a portion of the engine, and in particular illustrates a bearing compartment including a bearing assembly and a seal assembly. 
     
    
    
     DETAILED DESCRIPTION 
       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 . The fan section  22  drives air along a bypass flow path B in a bypass duct defined within a nacelle  15 , and also 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 two-spool 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 two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
     The exemplary 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, and the location of bearing systems  38  may be varied as appropriate to the application. 
     The low speed spool  30  generally includes an inner shaft  40  that interconnects, a first (or low) pressure compressor  44  and a first (or low) pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through a speed change mechanism, which in exemplary gas turbine engine  20  is illustrated as a geared architecture  48  to drive a 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 second (or high) pressure compressor  52  and a second (or high) pressure turbine  54 . A combustor  56  is arranged in exemplary gas turbine  20  between the high pressure compressor  52  and the high pressure turbine  54 . A mid-turbine frame  57  of the engine static structure  36  may be 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. 
     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 C. The turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. It will be appreciated that each of the positions of the fan section  22 , compressor section  24 , combustor section  26 , turbine section  28 , and fan drive gear system  48  may be varied. For example, gear system  48  may be located aft of the low pressure compressor, or aft of the combustor section  26  or even aft of turbine section  28 , and fan  42  may be positioned forward or aft of the location of gear system  48 . 
     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 about 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 five. 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 five 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 2.3:1 and less than about 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, low bypass engines, and multi-stage fan engines. 
     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 (10,668 meters). The flight condition of 0.8 Mach and 35,000 ft (10,668 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFCT’)”—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 (350.5 meters/second). 
       FIG. 2  is a partial cross-sectional view of a bearing compartment  60  of the engine  20 . The bearing compartment  60  includes a bearing assembly  62  and a seal assembly  64  configured to seal the bearing compartment  60  and maintain fluid pressure, particularly oil pressure, in the bearing compartment  60  during operation of the engine  20 . As is known in the art, the bearing assembly  62  may include an inner race, an outer race, and rolling elements, such as balls, configured to roll therebetween. The bearing assembly  62  is mounted relative to a shaft  66  of the engine  20 . The shaft  66  may be rotatably mounted about the engine central longitudinal axis A by one or more bearing assemblies, including additional bearing assemblies within the bearing compartment  60  or in other bearing compartments in the engine  20 . 
     To this end, the bearing compartment  60  is representative of any bearing compartment within the engine  20 . This disclosure is not limited to any specific bearing compartment, and in particular is not limited to a forward or an aft bearing compartment. Further, the shaft  66  represents either the inner shaft  40  or the outer shaft  50 . This disclosure is not limited to bearing compartments at any particular engine location. Further, this disclosure applies outside the context of bearing compartments, and extends to other engine compartments that are sealed. 
     The seal assembly  64  includes a seal  68  and a seal runner  70  configured to cooperate with one another to establish a seal for the bearing compartment  60 , and in particular to keep oil in the bearing compartment  60 , which, in turn, maintains oil pressure in the bearing compartment  60 . In this example, the seal  68  is mounted to a static structure, and therefore does not rotate during operation of the engine  20 . The seal  68  may be circumferentially segmented and may be made of a carbon (C) material, however other materials come within the scope of this disclosure. 
     In this disclosure, the seal  68  can either contact the seal runner  70  or have a gap between the seal  68  and seal runner  70  during operation of the engine  20 . In the latter example, the seal assembly  64  is known in the art as a non-contacting seal. In either case, the seal  68  and seal runner  70  are in a close relationship, and generate significant heat during operation of the gas turbine engine  20 . The relative spacing between the seal  68  and the seal runner  70  is important for maintaining pressure in the bearing compartment  60 . Thus, this disclosure provides cooling for the seal assembly  64  and minimizes deflection of the seal runner  70 , thereby maintaining a relatively constant spacing between the seal  68  and seal runner  70 . 
     The seal runner  70  of this disclosure includes an axially-extending portion  72  adjacent the seal  68 , and a deflector  74  that projects radially from an aft end  76  of the axially-extending portion  72 . In this disclosure “axially” refers to a direction substantially parallel to the engine central longitudinal axis A, and “radially” refers to directions normal thereto. The radial direction R is labeled in  FIG. 2  for ease of reference. 
     The deflector  74  is integrally formed with the seal runner  70  in this example. The deflector  74  serves to keep oil in the bearing compartment  60 , by deflecting a majority of the oil in the bearing compartment  60  away from the seal assembly  64 . While beneficial, the deflector  74  does add to the weight of the seal runner  70 , which may cause undesired deflection of the seal runner  70  during operation of the engine  20 . 
     In this disclosure, the seal runner  70  includes a tab  78  configured to contact a catcher  80 , which will be described below. The tab  78  is arranged adjacent the intersection of the axially-extending portion  72  and the deflector  74  (i.e., adjacent the aft end  76 ). The tab  78  projects radially inward of the axially-extending portion  72  and, adjacent the aft end  76 , projects aft of the deflector  74 . While in  FIG. 2  the tab  78  projects radially inward from the axially-extending portion  72 , the tab  78  could be radially in-line with the axially-extending portion  72  in another embodiment. 
     The catcher  80  is configured to contact the tab  78  and thereby substantially restrict, if not eliminate altogether, deflection of the seal runner  70 . In this example, the catcher  80  is integrally formed with a stack spacer  82  arranged about the shaft  66 . In other examples, the catcher  80  is not integrally formed with the stack spacer  82 , but is instead attached thereto by a known technique such as welding. 
     The catcher  80  in this example has a substantially L-shaped cross-section, and in particular includes a first leg  84  extending radially from the remainder of the stack spacer  82 , and a second leg  86  extending axially forward from a free end of the first leg  84 . The L-shaped cross-section of the catcher  80  makes the catcher  80  particularly suited to receive the tab  78 , and thereby prevent radial deflection of the seal runner  70 . In particular, in  FIG. 2 , a radially inner surface of the second leg  86  of the catcher  80  is in direct contact with a radially outer surface of a tab  78  of the seal runner  70 . 
     In addition to preventing deflection, this disclosure also provides for enhanced cooling of the seal assembly  64 . Oil F is configured to circulate within the bearing compartment  60  during operation of the engine  20 . In this example, oil F is introduced into the bearing compartment  60 , and is used to cool the seal assembly  64 . For instance, oil F is configured to flow in an axially forward direction in a space  88  radially between the stack spacer  82  and the shaft  66 . Adjacent the seal assembly  64 , the stack spacer  82  includes at least one orifice  90  configured to cause oil F to flow therethrough in the radial direction R such that the oil F impinges upon the inner surface of the seal runner  70  at a location adjacent the interface of the seal  68  and the seal runner  70 . The impingement cooling effect absorbs significant heat from the seal assembly  64 . 
     Next, the oil F turns aft and flows in a space  92  radially between the seal runner  70  and the stack spacer  82  toward the catcher  80 . In this example, the first leg  84  of the catcher  80  includes a plurality of passageways  94  extending therethrough and configured to permit the oil F to flow from space  92  into the bearing compartment  60 . Alternatively, the catcher  80  does not include spaces therethrough, and instead the stack spacer  82  could include a number of circumferentially spaced-apart catchers. In that instance, the oil F would flow into the bearing compartment  60  by passing between the catchers. 
     It should be understood that terms such as “axial,” “radial,” and “circumferential” are used above with reference to the normal operational attitude of the engine  20 . Further, these terms have been used herein for purposes of explanation, and should not be considered otherwise limiting. Terms such as “generally,” “substantially,” and “about” are not intended to be boundaryless terms, and should be interpreted consistent with the way one skilled in the art would interpret those terms. 
     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. In addition, the various figures accompanying this disclosure are not necessarily to scale, and some features may be exaggerated or minimized to show certain details of a particular component or arrangement. 
     One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.