Abstract:
A lubrication system for use with a gas turbine engine includes a first reservoir for containing a lubricant. The first reservoir includes a first discharge passage through which the lubricant is flowable in a first direction. A second reservoir contains the lubricant. The second reservoir includes a second discharge passage through which the lubricant is flowable in a second direction. The first direction is generally opposite to the second direction. A first pump pumps the lubricant from the first reservoir. A second pump pumps the lubricant from the second reservoir. A manifold distributes the lubricant to a component. The lubricant from the first pump and the second pump flows into the manifold and exits the manifold through a manifold discharge.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Some areas of a gas turbine engine require uninterrupted lubrication during engine operation. Example areas are bearings, such as rolling element bearings or journal bearings, or gears used throughout the engine and engine accessories. Lubricant is stored in a reservoir. 
         [0002]    A sudden change in attitude of the engine could move the lubricant in the reservoir, moving the lubricant away from a discharge passage. If this occurs, there could be an interruption in the supply of lubricant to the lubricated components. 
       SUMMARY OF THE INVENTION 
       [0003]    A lubrication system for use with a gas turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes, a first reservoir for containing a lubricant. The first reservoir includes a first discharge passage through which the lubricant is flowable in a first direction. A second reservoir contains the lubricant. The second reservoir includes a second discharge passage through which the lubricant is flowable in a second direction. The first direction is generally opposite to the second direction. A first pump pumps the lubricant from the first reservoir. A second pump pumps the lubricant from the second reservoir. A manifold distributes the lubricant to a component. The lubricant from the first pump and the second pump flows into the manifold and exits the manifold through a manifold discharge. 
         [0004]    In a further embodiment of any of the foregoing lubrication systems, the component is a bearing. 
         [0005]    In a further embodiment of any of the foregoing lubrication systems, the component is a fan journal bearing of a gas turbine engine. 
         [0006]    In a further embodiment of any of the foregoing lubrication systems, the first direction is substantially upwardly and the second direction is substantially downwardly. 
         [0007]    In a further embodiment of any of the foregoing lubrication systems, an output of each of the first pump and the second pump is greater than a lubrication requirement of the component. 
         [0008]    In a further embodiment of any of the foregoing lubrication systems, the lubricant flows directly from the manifold discharge of the manifold to the component. 
         [0009]    In a further embodiment of any of the foregoing lubrication systems, includes a valve. The lubricant flows from the manifold discharge of the manifold to the valve. 
         [0010]    In a further embodiment of any of the foregoing lubrication systems, the valve is a relief valve. 
         [0011]    In a further embodiment of any of the foregoing lubrication systems, the valve directs a portion of the lubricant to the component and a remainder of the lubricant to at least one of the first reservoir and the second reservoir. 
         [0012]    In a further embodiment of any of the foregoing lubrication systems, the valve closes if one of the first reservoir or the second reservoir is empty. 
         [0013]    In a further embodiment of any of the foregoing lubrication systems, the valve is a control valve. The lubrication system includes a sensor associated with each of the first reservoir and the second reservoir that detects an amount of the lubricant in each of the first reservoir and the second reservoir. The control valve directs the lubricant to the one of the first reservoir and the second reservoir if one of the sensors detects that the one of the first reservoir and the second reservoir is depleted of the lubricant. 
         [0014]    A lubrication system for use with a gas turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes, a first reservoir for containing a lubricant. The first reservoir includes a first discharge passage through which the lubricant is flowable in a first direction. A second reservoir containing a lubricant. The second reservoir includes a second discharge passage through which the lubricant is flowable in a second direction. The first direction is opposite to the second direction. A first pump pumps the lubricant from the first reservoir. A second pump pumps the lubricant from the second reservoir. A manifold distributes the lubricant to a bearing. The lubricant from the first pump and the second pump flows into the manifold and exits the manifold through a manifold discharge, and a valve. The lubricant flows from the manifold discharge of the manifold to the valve. 
         [0015]    In a further embodiment of any of the foregoing lubrication system, the component is a fan journal bearing of a gas turbine engine. 
         [0016]    In a further embodiment of any of the foregoing lubrication systems, the first direction is substantially upwardly and the second direction is substantially downwardly. 
         [0017]    In a further embodiment of any of the foregoing lubrication systems, an output of each of the first pump and the second pump is greater than a lubrication requirement of the component. 
         [0018]    In a further embodiment of any of the foregoing lubrication systems, the valve is a relief valve. 
         [0019]    In a further embodiment of any of the foregoing lubrication systems, the valve directs a portion of the lubricant to the component and a remainder of the lubricant to at least one of the first reservoir and the second reservoir. 
         [0020]    In a further embodiment of any of the foregoing lubrication systems, the valve closes if one of the first reservoir or the second reservoir is empty. 
         [0021]    In a further embodiment of any of the foregoing lubrication systems, the valve is a control valve. The lubrication system includes a sensor associated with each of the first reservoir and the second reservoir that detects an amount of the lubricant in each of the first reservoir and the second reservoir. The control valve directs the lubricant to the one of the first reservoir and the second reservoir if one of the sensors detects that the one of the first reservoir and the second reservoir is depleted of the lubricant. 
         [0022]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  illustrates a schematic view of an embodiment of a gas turbine engine; and 
           [0024]      FIG. 2  illustrates a lubrication system. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]      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. 
         [0026]    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 or geared turbofan architectures. 
         [0027]    The fan section  22  drives air along a bypass flowpath B while the compressor section  24  drives air along a core flowpath C for compression and communication into the combustor section  26  then expansion through the turbine section  28 . 
         [0028]    The gas turbine 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. For example, the bearing system  38  also includes fan journal bearings  38   a.    
         [0029]    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 a high pressure turbine  54 . 
         [0030]    A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . 
         [0031]    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 . 
         [0032]    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. 
         [0033]    The core airflow C 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  58  includes airfoils  60  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. 
         [0034]    The gas turbine engine  20  is in one example a high-bypass geared aircraft engine. In a further example, the gas turbine engine  20  bypass ratio is greater than about six (6:1) with an example embodiment being greater than ten (10:1). 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 (2.3:1). The low pressure turbine  46  has a pressure ratio that is greater than about five (5:1). The 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. 
         [0035]    In one disclosed embodiment, the gas turbine engine  20  bypass ratio is greater than about ten (10:1), and the fan diameter is significantly larger than that of the low pressure compressor  44 . The low pressure turbine  46  has a pressure ratio that is greater than about five (5:1). 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 (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. 
         [0036]    A significant amount of thrust is provided by the bypass flow B 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. The flight condition of 0.8 Mach and 35,000 feet, with the engine at its best fuel consumption, also known as bucket cruise Thrust Specific Fuel Consumption (“TSFC”). TSFC is the industry standard parameter of 1 bm of fuel being burned divided by 1 bf of thrust the engine produces at that minimum point. 
         [0037]    “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. 
         [0038]    “Low corrected fan tip speed” is the actual fan tip speed in feet per second divided by an industry standard temperature correction of [(Tram ° R)/518.7) 0. 5 ]. The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 feet per second (351 meters per second). 
         [0039]    As shown in  FIG. 2 , the gas turbine engine  20  includes a lubrication system  62  that lubricates the bearing system  38 . In one example, the lubrication system  62  lubricates the fan journal bearings  38   a.  The lubrication system  62  provides a constant and uninterrupted supply of lubricant. In one example, the lubricant is oil. The lubrication system  62  does not depend on gravity or valves for operation. The lubrication system  62  is also tolerant of debris and can operate autonomously. 
         [0040]    The lubrication system  62  includes a first reservoir  64  and a second reservoir  66  that each contain the lubricant. At least one of the reservoirs  64  and  66  continuously supplies the lubricant to the bearing system  38  under any operating condition. 
         [0041]    The first reservoir  64  includes a first discharge passage  68  that directs the lubricant to flow from the first reservoir  64  in a first direction X. In this example, the direction X is generally downwardly. The second reservoir  66  includes a second discharge passage  70  that directs the lubricant to flow from the second reservoir  66  in a second direction Y. In this example, the direction Y is generally upwardly. In this example, the direction X is opposite to the direction Y. 
         [0042]    The lubricant in the discharge passage  68  flows to a first pump  72 , and the lubricant in the second discharge passage  70  flows to a second pump  74 . The pumps  72  and  74  are each sized so that the individual output of each of the pumps  72  and  74  or the combined output of the pumps  72  and  74  exceed the lubrication or cooling requirements of the bearing system  38 . Although two reservoirs  64  and  66  and two pumps  72  and  84  are illustrated and described, any number of reservoirs and pumps can be employed in the lubrication system  62 . 
         [0043]    The first pump  72  and the second pump  74  supply the lubricant to a common manifold  76  through the discharge passages  68  and  70 , respectively. The lubricant is discharged from the common manifold  76  through a common discharge  78  and ultimately to the bearing system  62 . As the flow of the lubricant through the discharge passages  68  and  70  are in generally opposing directions, there is a constant and uninterrupted supply of lubricant in case of a sudden change in altitude of the aircraft or if the aircraft encounters an air pocket. 
         [0044]    For example, if the aircraft suddenly drops, the lubricant in the reservoirs  64  and  66  moves towards the upper portion of the reservoirs  64  and  66 . This could interrupt the flow of lubricant through the discharge passage  68  that directs the lubricant downwardly. However, as the discharge passage  70  directs the lubricant upwardly, the lubricant can continue to flow in an uninterrupted manner through the discharge passage  70 . 
         [0045]    In another example, if the aircraft suddenly rises, the lubricant in the reservoirs  64  and  66  moves towards the lower portion of the reservoirs  64  and  66 . This could interrupt the flow of lubricant through the discharge passage  70  that directs the lubricant upwardly. However, as the discharge passage  68  directs the lubricant downwardly, the lubricant can continue to flow in an uninterrupted manner through the discharge passage  68 . 
         [0046]    In one example, the lubricant flows directly from the common discharge  78  of the common manifold  76  to the bearing system  38 . 
         [0047]    In another example, the lubricant flows from the common discharge  78  of the common manifold  76  to a valve  80 . The valve  80  directs the flow of the lubricant to the bearing system  38  and the reservoirs  64  and  66  as needed. 
         [0048]    In one example, the valve  80  is a relief valve, which is passive valve. The valve  80  directs the lubricant to the bearing system  38  and returns any excess lubricant to replenish the first reservoir  64  and the second reservoir  66 . 
         [0049]    If one of the reservoirs  64  and  66  is empty, the discharge pressure of the lubricant system  62  drops, closing the valve  80 . The pumps  72  and  74  continue to operate, and the pump  72  and  74  associated with the depleted reservoir  64  and  66  pumps air because the lubricant is depleted (for example, because of altitude or gravity vector location, etc.). Initially, the flow of the lubricant from the full reservoir  64  and  66  creates a seal at the valve  80  that blocks the flow of air from the empty reservoir  64  and  66  into the valve  80 . The lubricant from the reservoir  64  and  66  is pumped to the valve  80 , which directs the lubricant to the reservoir  64  and  66  that is empty. When both the reservoirs  64  and  66  are filled with the lubricant, the lubrication system  62  returns to its initial state. The valve  80  can then be opened by pressure. 
         [0050]    In another example, the valve  80  is a control valve, which is an active valve. Each of the reservoirs  64  and  66  includes a sensor  82  that detects an amount of the lubricant in each of the reservoirs  64  and  66 . This information is provided to the valve  80 . Based on the information obtained by the sensors  82 , the valve  80  can be opened to return the excess lubricant to the reservoir  64  and  66  with the depleted lubricant. 
         [0051]    In another example, the reservoirs  64  and  66  are in direct communication with each other. In this example, the reservoirs  64  and  66  can supply lubricant to each other when needed to prevent depletion of the lubricant in either of the reservoirs  64  and  66 . 
         [0052]    Although a gas turbine engine  20  with geared architecture  48  is described, the lubrication system  62  can be employed in a gas turbine engine without geared architecture. 
         [0053]    The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.