Patent Publication Number: US-2017362959-A1

Title: Lubrication system with multiple lubrication circuits

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This disclosure relates generally to a gas turbine engine and, more particularly, to a lubrication system with multiple pumps. 
     2. Background Information 
     A gas turbine engine includes numerous bearings as well as a lubrication system to lubricate the bearings as well as other components of the gas turbine engine. Various types and configurations of lubrication systems are known in the art. While known lubrication systems have various advantages, there is still room in the art for improvement. In particular, there is a need in the art for an improved lubrication system which reduces cost, complexity and/or weight of a gas turbine engine. 
     SUMMARY OF THE DISCLOSURE 
     According to an aspect of the present disclosure, a system is provided for a turbine engine. This turbine engine system includes a first bearing, a second bearing, a first rotating assembly, a second rotating assembly, a first lubrication circuit and a second lubrication circuit. The first rotating assembly includes a first component rotatably supported by the first bearing. The second rotating assembly includes a second component rotatably supported by the second bearing. The first lubrication circuit includes a first pump and the first bearing. The first pump is driven by the first rotating assembly and configured to pump lubricant to the first bearing. The second lubrication circuit includes a second pump and the second bearing. The second pump is configured to pump lubricant to the second bearing. The second lubrication circuit is configured discrete from the first lubrication circuit. 
     According to another aspect of the present disclosure, another system is provided for a turbine engine. This turbine engine system includes a first bearing, a second bearing, a first rotating assembly, a second rotating assembly, a first lubrication circuit and a second lubrication circuit. The first rotating assembly includes a first component rotatably supported by the first bearing. The second rotating assembly includes a second component rotatably supported by the second bearing. The first lubrication circuit includes a first pump and the first bearing. The first pump is driven by the first rotating assembly and configured to pump lubricant to the first bearing during nominal operation of the turbine engine. The second lubrication circuit includes a second pump and the second bearing. The second pump is configured to pump lubricant to the second bearing during the nominal operation of the turbine engine. 
     According to still another aspect of the present disclosure, another system is provided for a turbine engine. This turbine engine system includes a first rotating assembly, a second rotating assembly, a first lubrication circuit and a second lubrication circuit. The first rotating assembly includes a fan rotor, a first compressor rotor and a first turbine rotor mechanically coupled to the fan rotor and the first compressor rotor. A first component of the first rotating assembly is rotatably supported by a first bearing. The second rotating assembly includes a second compressor rotor and a second turbine rotor mechanically coupled to the second compressor rotor. A second component of the second rotating assembly is rotatably supported by a second bearing. The first lubrication circuit includes a first pump and the first bearing. The first pump is driven by the first rotating assembly and configured to pump lubricant to the first bearing. The second lubrication circuit includes a second pump and the second bearing. The second pump is configured to pump lubricant to the second bearing. The second lubrication circuit is configured discrete from the first lubrication circuit and the first bearing during nominal operation of the turbine engine. 
     The first pump may be configured to pump lubricant to the first bearing during nominal operation of the turbine engine. The second pump may be configured to pump lubricant to the second bearing during the nominal operation of the turbine engine. 
     The first rotating assembly may include a fan rotor. The first pump may be configured to pump lubricant to the first bearing during wind milling of the fan rotor. 
     The system may include a lubricant reservoir. The first lubrication circuit and the second lubrication circuit may be configured in parallel with one another and fluidly coupled with the lubricant reservoir. 
     The first lubrication circuit may be fluidly isolated from the second lubrication circuit. 
     The first lubrication circuit may include a first lubricant. The second lubrication circuit may include a second lubricant. The first lubricant may be different from (or the same as) the second lubricant. 
     The first bearing may be configured as or otherwise include a thrust bearing. 
     The first bearing may be configured as or otherwise include a journal bearing. 
     The first rotating assembly may include a gear system that includes the first component. 
     The first rotating assembly may include a compressor rotor and a turbine rotor. The first component may be a shaft connected between the compressor rotor and the turbine rotor. 
     The first rotating assembly may include a fan rotor, a gear system, a first shaft, a first compressor rotor and a first turbine rotor. The first shaft may be connected between the first compressor rotor and the first turbine rotor, and may be connected to the fan rotor through the gear system. The first component may include a component of the gear system or the first shaft. 
     The system may include a third bearing supporting the first shaft, the third bearing included in and lubricated by first lubrication circuit. The first component may include the component of the gear system. 
     The second rotating assembly may include a second compressor rotor and a second turbine rotor. The second component may include a second shaft that is connected between the second compressor rotor and the second turbine rotor. 
     The second pump may be driven by the second rotating assembly. 
     The second pump may be an electric pump. 
     The first rotating assembly may include a fan rotor. The first pump may be configured to pump lubricant to the first bearing during wind milling of the fan rotor. 
     The second lubrication circuit may be configured discrete from the first lubrication circuit. 
     The first rotating assembly may include a fan rotor, a gear system, a first shaft, a first compressor rotor and a first turbine rotor. The first shaft may be connected between the first compressor rotor and the first turbine rotor, and may be connected to the fan rotor through the gear system. The first component may include a component of the gear system or the first shaft. 
     The second rotating assembly may include a second compressor rotor and a second turbine rotor. The second component may include a second shaft that is connected between the second compressor rotor and the second turbine rotor. 
     The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cutaway illustration of an embodiment of a geared turbine engine. 
         FIG. 2  is a side sectional illustration of a portion of the geared turbine engine of  FIG. 1 , which includes a gear train. 
         FIG. 3  is a cross-sectional illustration of the gear train of  FIG. 2 . 
         FIG. 4  is a schematic illustration of an embodiment of a system for the geared turbine engine which includes fluidly discrete lubrication circuits. 
         FIG. 5  is a schematic illustration of another embodiment of a system for the geared turbine engine which includes fluidly isolated lubrication circuits. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a side cutaway illustration of a geared turbine engine  20 . This turbine engine  20  extends along an axial centerline  22  between an upstream airflow inlet  24  and a downstream airflow exhaust  26 . The turbine engine  20  includes a fan section  28 , a compressor section  29 , a combustor section  30  and a turbine section  31 . The compressor section  29  includes a low pressure compressor (LPC) section  29 A and a high pressure compressor (HPC) section  29 B. The turbine section  31  includes a high pressure turbine (HPT) section  31 A and a low pressure turbine (LPT) section  31 B. 
     The engine sections  28 - 31  are arranged sequentially along the centerline  22  within an engine housing  32 . This housing  32  includes an inner case  34  (e.g., a core case) and an outer case  36  (e.g., a fan case). The inner case  34  may house one or more of the engine sections  29 - 31 ; e.g., an engine core. The outer case  36  may house at least the fan section  28 . 
     Each of the engine sections  28 ,  29 A,  29 B,  31 A and  31 B includes a respective rotor  38 - 42 . Each of these rotors  38 - 42  includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s). 
     The fan rotor  38  is connected to a gear train  44 , for example, through a fan shaft  46 . The gear train  44  and the LPC rotor  39  are connected to and driven by the LPT rotor  42  through a low speed shaft  47 . The HPC rotor  40  is connected to and driven by the HPT rotor  41  through a high speed shaft  48 . In this manner, the components  38 ,  39 ,  42 ,  46  and  47  are configured into a first (e.g., low speed) rotating assembly and the components  40 ,  41  and  48  are configured into a second (e.g., high speed) rotating assembly. The shafts  46 - 48  and/or other components of the rotating assemblies are rotatably supported by a plurality of bearings  50 - 52 ; e.g., rolling element and/or thrust bearings. Each of these bearings  50 - 52  is connected to the engine housing  32  by at least one stationary structure such as, for example, an annular support strut. 
     During operation, air enters the turbine engine  20  through the airflow inlet  24 . This air is directed through the fan section  28  and into a core gas path  54  and a bypass gas path  56 . The core gas path  54  extends sequentially through the engine sections  29 A,  29 B,  30 ,  31 A and  31 B. The bypass gas path  56  extends away from the fan section  28  through a bypass duct, which circumscribes and bypasses the engine core. The air within the core gas path  54  may be referred to as “core air”. The air within the bypass gas path  56  may be referred to as “bypass air”. 
     The core air is compressed by the compressor rotors  39  and  40  and directed into a combustion chamber  58  of a combustor in the combustor section  30 . Fuel is injected into the combustion chamber  58  and mixed with the compressed core air to provide a fuel-air mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors  41  and  42  to rotate. The rotation of the turbine rotors  41  and  42  respectively drive rotation of the compressor rotors  40  and  39  and, thus, compression of the air received from a core airflow inlet. The rotation of the turbine rotor  42  also drives rotation of the fan rotor  38  through the gear train  44 , which propels bypass air through and out of the bypass gas path  56 . The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine  20 , e.g., more than seventy-five percent (75%) of engine thrust. The turbine engine  20  of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio. 
     The gear train  44  is configured to interconnect and provide a rotational speed reduction between the LPT rotor  42  and the fan rotor  38 . For example, referring to  FIGS. 2  and  3 , the gear train  44  may include a plurality of gears  60 - 62  arranged in a star gear train configuration. Alternatively, the gears  60 - 62  may be arranged in a planetary gear train configuration, or any other type of gear train configuration. 
     The gears of  FIGS. 2 and 3  include a sun gear  60 , one or more intermediate gears  61  (e.g., either star gears as shown or planetary gears) and a ring gear  62 . The sun gear  60  is rotatable about the centerline  22 . The sun gear  60  is connected to the low speed shaft  47  through a joint such as, but not limited to, a spline joint. The star gears  61  are arranged circumferentially around the sun gear  60  and the centerline  22 . The star gears  61  are radially meshed between the sun gear  60  and the ring gear  62 . Each of the star gears  61  is rotatably connected to a gear carrier  64  and rotatably supported by a respective bearing  66 . This bearing  66  may be a journal bearing as shown in  FIGS. 2 and 3 , or alternatively any other type of bearing such as a rolling element bearing. The gear carrier  64  is connected to the engine housing  32  (e.g., the inner case  34 ; see  FIG. 1 ) through a stationary support structure. The ring gear  62  is connected to the fan shaft  46  through a joint such as, but not limited to, a bolted flange joint. 
       FIG. 4  is a schematic illustration of a system  68  of the turbine engine  20  of  FIG. 1 . This turbine engine system  68  includes one or more components (e.g.,  44 ,  46  and  47 ) of the first rotating assembly. The turbine engine system  68  includes at least one component (e.g.,  48 ) of the second rotating assembly. The turbine engine system  68  also includes a lubrication system  74  configured to lubricate one or more of the bearings (e.g.,  50 ,  51 ,  52  and  66 ), where the bearings  50 ,  51  and  66  are in a first bearing compartment  76  and the bearings  52  are in one or more other bearing compartments  78  (see also  FIGS. 1 and 2 ). The lubrication system  74  is configured as a multi-circuit system and includes a lubricant reservoir  80  (e.g., a tank, a sump, a fluid container), a first lubrication circuit  82  and a second lubrication circuit  84 . 
     The first lubrication circuit  82  extends between a first inlet  86  and a first outlet  88 , which inlet  86  and outlet  88  are fluidly coupled with the reservoir  80 . The first lubrication circuit  82  includes a lubricant first pump  90  and one or more of the bearings (e.g.,  50 ,  51  and  66 ). These first lubrication circuit components  90  and  50 ,  51 ,  66  are arranged sequentially inline between the first inlet  86  and the first outlet  88 . More particularly, the first lubrication circuit components  90  and  50 ,  51 ,  66  are respectively serially fluidly coupled together by inter-circuit first flowpaths  92 . Each first flowpath  92  may be configured as or include a conduit, a pipe, a hose and/or any type of fluid passage (e.g., channel, cavity, etc.) formed by another structure. 
     The first pump  90  is configured as a mechanical pump. This first pump  90  is mechanically coupled to and, thereby, driven by a component of the first rotating assembly. For example, the first pump  90  may be mechanically coupled to the low speed shaft  47  through a first accessory gearbox  94  and a first drivetrain  96  (e.g., a tower shaft). 
     The second lubrication circuit  84  extends between a second inlet  98  and a second outlet  100 , which inlet  98  and outlet  100  are fluidly coupled with the reservoir  80 . The second lubrication circuit  84  includes a lubricant second pump  102  and one or more of the bearings (e.g.,  52 ). These second lubrication circuit components  102  and  52  are arranged sequentially inline between the second inlet  98  and the second outlet  100 . More particularly, the second lubrication circuit components  102  and  52  are respectively serially fluidly coupled together by inter-circuit second flowpaths  104 . Each second flowpath  104  may be configured as or include a conduit, a pipe, a hose and/or any type of fluid passage (e.g., channel, cavity, etc.) formed by another structure. 
     The second pump  102  is configured as a mechanical pump. This second pump  102  is mechanically coupled to and, thereby, driven by a component of the second rotating assembly. For example, the second pump  102  may be mechanically coupled to the high speed shaft  48  through a second accessory gearbox  106  and a second drivetrain  108  (e.g., a tower shaft). 
     The second lubrication circuit  84  is configured fluidly parallel with the first lubrication circuit  82 . The second lubrication circuit  84  is also thereby fluidly discrete from the first lubrication circuit  82 . For example, the lubrication system  74  embodiment of  FIG. 4  does not include any inter-circuit connections between the inlets  86 ,  98  and the outlets  88 ,  100 . Rather, the only connection between the circuits  82  and  84  shown in the  FIG. 4  embodiment is through the reservoir  80 , which is not within the circuits  82  and  84  between the inlets  86 ,  98  and the outlets  88 ,  100 . 
     With the above described lubrication system  74  configuration, the first lubrication circuit  82  is configured to service (e.g., exclusively lubricate relative to circuit  84 ) the bearings  50 ,  51  and  66  during nominal operation of the turbine engine  20 ; e.g., aircraft takeoff, aircraft landing, aircraft taxiing, aircraft flight at cruise, etc. The second lubrication circuit  84  is configured to service (e.g., exclusively lubricate relative to circuit  82 ) the bearings  52  during the nominal operation of the turbine engine  20 . A flow of lubricant through each lubrication circuit  82 ,  84  may therefore be proportional to the rotational speed of the components being supported by the bearings in that circuit  82 ,  84  and, thus, specified lubrication requirements for those bearings. This also enables use of smaller and more tailored pumps  90 ,  102 . In contrast, where the rotational speed is not proportional to the specified lubrication requirements, a lubricant pump may be oversized in order to pump enough lubricant at lower rotational speeds. 
     In addition to the foregoing, since the bearings  50 ,  51  and  66  receive lubricant from the first pump  90  which is driven by the first rotating assembly, the first lubrication circuit  82  may also service the bearings  50 ,  51  and  66  during non-nominal operation of the turbine engine  20 ; e.g., during fan rotor  38  wind milling conditions, etc. Thus, the first lubrication circuit  82  may replace sometimes complicated, expensive and/or heavy auxiliary lubrications systems which may otherwise be required to lubricate certain components during the non-nominal operation of the turbine engine  20 . 
     In some embodiments, referring to  FIG. 5 , the first lubrication circuit  82  may be fluidly isolated from the second lubrication circuit  84 . The lubrication system  74  of  FIG. 5 , for example, replaces the reservoir  80  of  FIG. 4  with a first reservoir  80 A and a second reservoir  80 B. The first and the second reservoirs  80 A and  80 B are separate and discrete; e.g., fluidly decoupled and distinct. The first reservoir  80 A is fluidly coupled between the first inlet  86  and the first outlet  88 . The second reservoir  80 B is fluidly coupled between the second inlet  98  and the second outlet  100 . In such an embodiment, the first reservoir  80 A may contain a first type of lubricant and the second reservoir  80 B may contain a second type of lubricant that is different than the first type. For example, the first reservoir  80 A may contain a relatively high viscosity lubricant (e.g., oil). The second reservoir  80 B may contain a high thermal stability (HTS) lubricant (e.g., oil). Such a HTS lubricant is operable to withstand relatively high temperatures associated with bearings  52  located in the turbine section  31 , but typically may have a lower viscosity. Of course, the present disclosure is not limited to the foregoing exemplary lubricants. Furthermore, in other embodiments, the lubricant within the reservoirs  80 A and  80 B may be the same. 
     In some embodiments, the second pump  102  may be configured as an electric pump. 
     In some embodiments, the first lubrication circuit  82  and the second lubrication circuit  84  may each include one or more additional components. Examples of such additional components include, but are not limited to, a filter, a sensor, a manifold, another lubricant reservoir, another lubricant pump, etc. 
     In some embodiments, the bearings  50 ,  51  and  66  may be fluidly configured in parallel with one another. In other embodiments, one or more of the bearings  50 ,  51  and/or  66  may be fluidly configured in series with one another. 
     In some embodiments, the bearings  52  may be fluidly configured in parallel with one another. In other embodiments, one or more of the bearings  52  may be fluidly configured in series with one another. 
     In some embodiments, the lubrication system  74  may also be configured as a heat exchange system. For example, the lubricant in the first lubrication circuit  82  and/or the second lubrication circuit  84  may be routed through another element to exchange thermal energy therewith. 
     In some embodiments, the first pump  90  may be located upstream of the bearings  50 ,  51  and  66  as illustrated in  FIG. 4 . Alternatively, the first pump  90  may be located downstream of the bearings  50 ,  51  and  66 , or between two serially fluidly adjacent bearings  50 ,  51 ,  66 . 
     In some embodiments, the second pump  102  may be located upstream of the bearings  52  as illustrated in  FIG. 4 . Alternatively, the second pump  102  may be located downstream of the bearings  52 , or between two serially fluidly adjacent bearings  52 . 
     In some embodiments, the first pump  90  may be configured with a rotor lock. This rotor lock may be configured to selectively engage so as to prevent rotation of the first rotating assembly, for example, when an aircraft is parked on a runway to prevent fan rotor  38  wind milling. 
     The turbine engine system  68  may be included in various turbine engines other than the one described above. The turbine engine system  68 , for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the turbine engine system  68  may be included in a turbine engine configured without a gear train. The turbine engine system  68  may be included in a geared or non-geared turbine engine configured with two spools (e.g., see  FIG. 1 ) or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present invention therefore is not limited to any particular types or configurations of turbine engines. 
     While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. For example, the present invention as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present invention that some or all of these features may be combined with any one of the aspects and remain within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.