Patent Publication Number: US-10787929-B2

Title: Lubricating fluid damped anti-rotational systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/903,371, filed Feb. 23, 2018 and entitled “LUBRICATING FLUID DAMPED ANTI-ROTATIONAL SYSTEMS,” which is a divisional of U.S. application Ser. No. 14/660,516, filed Mar. 17, 2015, now U.S. Pat. No. 9,932,859, which claims priority to and the benefit of U.S. Prov. Appl. No. 61/977,827, filed Apr. 10, 2014 and entitled “LUBRICATING FLUID DAMPED ANTI-ROTATIONAL SYSTEMS,” each of which is hereby incorporated by reference for all purposes. 
    
    
     FIELD 
     The present disclosure relates to lubricating fluid damped anti-rotational systems and methods, and more specifically, to lubricating fluid damped anti-rotational systems and methods applicable to turbine engines. 
     BACKGROUND 
     Turbine engines typically windmill when idle. A turbine engine will often windmill due to wind blowing through the engine. Many times, wind enters through the engine outlet, causing the engine to windmill in reverse. Many turbine engines do not have a feature to prevent the reverse wind milling of the engine or utilize a complex and/or heavy system to accomplish this feature. Moreover, forward wind milling is often desired, for example, to enable the engine to more readily restart in flight. Reverse wind milling is not desired, for example, to reduce wear on the engine when idle. A turbine engine typically has a system to facilitate lubrication of rotating components when idle, but often this system only lubricates the rotating components when the engine is forward wind milling. Thus, reverse wind milling is often not desired. 
     SUMMARY 
     A lubricating fluid damped anti-rotational system is provided comprising, a pawl carrier having an axis of rotation and a first radial aperture, a pawl pivotably mounted to the pawl carrier on a pivot joint, the pawl having a contact portion and a counterweight portion, a lubricating fluid jet configured to propel a lubricating fluid through the first radial aperture toward the counterweight portion. 
     A method comprising, rotating a pawl carrier having an axis of rotation and a radial aperture and a pawl pivotably mounted to the pawl carrier on a pivot joint, the pawl having a contact portion and a counterweight portion, propelling a lubricating fluid through the radial aperture toward the contact portion. 
     In various embodiments, a stop pin is axially disposed in the pawl carrier and configured to contact the contact portion of the pawl in response to radially inward movement of the pawl. In various embodiments, the radial aperture is radially inward of the stop pin. In various embodiments, the lubricating fluid comprises an oil. In various embodiments, the lubricating fluid jet is configured to propel the lubricating fluid in a pulsed manner. In various embodiments, the lubricating fluid jet is configured to propel the lubricating fluid in a continuous manner. In various embodiments, the lubricating fluid jet is configured to distribute the lubricating fluid to a pawl nut. In various embodiments, a torsion spring is coupled to the pivot joint. In various embodiments, the torsion spring is coupled to the pivot joint to cause the contact portion to rotate radially outward relative to the pawl carrier. In various embodiments, a stop pin is axially disposed in the pawl carrier and configured to contact the contact portion of the pawl in response to radially inward movement of the pawl. In various embodiments, the lubricating fluid damped anti-rotational system further comprises a second radial aperture. In various embodiments, the lubricating fluid comprises an oil. In various embodiments, the lubricating fluid jet is configured to propel the lubricating fluid in a pulsed manner. In various embodiments, the lubricating fluid jet is configured to propel the lubricating fluid in a continuous manner. In various embodiments, the lubricating fluid jet is configured to distribute the lubricating fluid to a pawl nut. In various embodiments, the lubricating fluid damped anti-rotational system further comprises a torsion spring coupled to the pivot joint. In various embodiments, the torsion spring is coupled to the pivot joint to cause the counterweight portion to rotate radially inward relative to the pawl carrier. In various embodiments, the propelling is continuous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements. 
         FIG. 1  illustrates a turbofan engine; 
         FIGS. 2A and 2B  illustrate a pawl carrier according to various embodiments; 
         FIGS. 3A and 3B  illustrate a pawl and pawl carrier according to various embodiments; 
         FIGS. 4A and 4B  illustrates a lubricating fluid damped pawl carrier in various embodiments; and 
         FIG. 5  illustrates a lubricating fluid damped pawl carrier in various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical, chemical and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. 
     Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. 
     As used herein, phrases such as “make contact with,” “coupled to,” “touch,” “interface with” and “engage” may be used interchangeably. 
     As used herein, “aft” refers to the direction associated with the tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of the gas turbine engine. As used herein, “forward” refers to the direction associated with the nose (e.g., the front end) of an aircraft, or generally, to the direction of flight or motion. 
     As used herein, a “lubricating fluid” may refer to a fluid that is suitable for use in lubricating two or more surfaces. For example, a lubricating fluid may reduce friction between two or more contacting surfaces. In various embodiments, a lubricating fluid may comprise an oil, whether the oil is naturally occurring or synthetic. 
     In various embodiments and with reference to  FIG. 1 , a gas turbine engine  20  is provided. Gas turbine engine  20  may be 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 may include, for example, an augmentor section among other systems or features. In operation, fan section  22  can drive air along a bypass flow-path B while compressor section  24  can drive air along a core flow-path C for compression and communication into combustor section  26  then expansion through turbine section  28 . Although depicted as a turbofan gas turbine engine  20  herein, 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 architectures. 
     Gas turbine engine  20  may generally comprise a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A-A′ relative to an engine static structure  36  via several bearing systems  38 ,  38 - 1 , and  38 - 2 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided, including for example, bearing system  38 , bearing system  38 - 1 , and bearing system  38 - 2 . 
     Low speed spool  30  may generally comprise an inner shaft  40  that interconnects a fan  42 , a low pressure (or first) compressor section  44  and a low pressure (or first) turbine section  46 . Inner shaft  40  may be connected to fan  42  through a geared architecture  48  that can drive fan  42  at a lower speed than low speed spool  30 . Geared architecture  48  may comprise a gear assembly  60  enclosed within a gear housing  62 . Gear assembly  60  couples inner shaft  40  to a rotating fan structure. High speed spool  32  may comprise an outer shaft  50  that interconnects a high pressure (or second) compressor section  52  and high pressure (or second) turbine section  54 . A combustor  56  may be located between high pressure compressor  52  and high pressure turbine  54 . A mid-turbine frame  57  of engine static structure  36  may be located generally between high pressure turbine  54  and low pressure turbine  46 . Mid-turbine frame  57  may support one or more bearing systems  38  in turbine section  28 . Inner shaft  40  and outer shaft  50  may be concentric and rotate via bearing systems  38  about the engine central longitudinal axis A-A′, which is collinear with their longitudinal axes. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine. 
     The core airflow C may be compressed by low pressure compressor  44  then high pressure compressor  52 , mixed and burned with fuel in combustor  56 , then expanded over high pressure turbine  54  and low pressure turbine  46 . Mid-turbine frame  57  includes airfoils  59  which are in the core airflow path. Turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. 
     Gas turbine engine  20  may be, for example, a high-bypass geared aircraft engine. In various embodiments, geared architecture  48  may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. Gear architecture  48  may have a gear reduction ratio of greater than about 2.3 and low pressure turbine  46  may have a pressure ratio that is greater than about 5. In various embodiments, the bypass ratio of gas turbine engine  20  is greater than about ten (10:1). In various embodiments, the diameter of fan  42  may be significantly larger than that of the low pressure compressor  44 , and the low pressure turbine  46  may have a pressure ratio that is greater than about 5:1. Low pressure turbine  46  pressure ratio may be measured prior to inlet of low pressure turbine  46  as related to the pressure at the outlet of low pressure turbine  46  prior to an exhaust nozzle. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other gas turbine engines including direct drive turbofans. 
     With reference to  FIG. 1 , gas turbine engine  20  may generally include multiple of modules including for example, a fan case module  61 , an intermediate case module  63 , a Low Pressure Compressor (LPC) module  64 , a High Pressure Compressor (HPC) module  66 , a diffuser module  68 , a High Pressure Turbine (HPT) module  70 , a mid-turbine frame (MTF) module  72 , a Low Pressure Turbine (LPT) module  74 , and a Turbine Exhaust Case (TEC) module  76 . 
     As described above, an anti-rotational device may be used to prevent reverse wind-milling in a turbofan engine. In particular, an anti-rotational device may be disposed in the low pressure turbine to prevent rotation in an undesired direction. For example, an anti-rotational device may be configured to allow rotation in a first direction (e.g., clockwise) and to limit all or nearly all rotation in a second direction (e.g., counter clockwise). Moreover, an anti-rotational device may be configured to limit mechanical contact at or above certain angular velocities. In that regard, lower angular velocities may be associated with a level of mechanical contact between various components but, after a low pressure turbine achieves a given angular velocity, the contact may be reduced or eliminated. However, such anti-rotational device may exhibit undesired vibration, for example, when rotation proceeds at an angular velocity below a predetermined angular velocity. 
     With reference to  FIGS. 2A and 2B , pawl system  200  is shown. Pawl carrier  206  is shown coupled to pawl  202 . Stop pin  204  is shown disposed in pawl carrier  206 . Pawl carrier  206  may comprise any number of pawls, for example, from 1 pawl to 20 pawls. Pawl nut  218  coupled pawl carrier  206  to a low pressure turbine shaft, which drives rotation of pawl carrier  206 . In various embodiments, any number of pawls may be used, and thus the selection of the appropriate number of pawls and the spacing of the pawls may be tuned in response to design weight constraints, footprint, and other manufacturing concerns. In various embodiments, pawl carrier  206  comprises three pawls distributed uniformly about the circumference of pawl carrier  206 . 
     Pawl  202  may be comprised of any suitable material. For example, pawl  202  may be comprised of stainless steel such as 300M stainless steel and/or a chromium-nickel-tungsten martensitic alloy (also known as Greek Ascoloy). In various embodiments, various components disclosed herein may comprise 300M stainless steel and/or chromium-nickel-tungsten martensitic alloy (also known as Greek Ascoloy) and/or austenitic nickel-chromium-based alloy such as Inconel® which is available from Special Metals Corporation of New Hartford, N.Y., USA, or any other metal, for example, titanium. However, in further embodiments, various components of anti-rotational devices may comprise other metals, such as tungsten, aluminum, steel, or alloys, though they may further comprise numerous other materials configured to provide mechanical resiliency and/or support of the system when subjected to wear in an operating environment or to satisfy other desired electromagnetic, chemical, physical, or biological properties such as strength, durability, ductility, heat tolerance, thermal dissipation, and footprint constraints, among others. In various embodiments, various portions of anti-rotational devices as disclosed herein are made of different materials or combinations of materials, and/or may comprise various coatings. 
     With brief reference to  FIG. 3A , pawl  202  is shown pivotably mounted to pawl carrier  206  on a pivot joint  302 . Pivot joint  302  allows pawl  202  to rotate freely about pivot joint  302 . Pivot joint  302  may comprise any suitable joint that is configured to allow pawl  202  to pivot. For example, a post and bushing mating may be used as pivot joint  302 . Pivot joint  302  may be suitably lubricated, for example, using a solid state lubricant and/or liquid lubricant. Pivot joint  302  may also comprise one or more materials that are coated with or comprised of a low friction material. For example, portions of pivot joint  302  may be coated with polytetrafluoroethylene (“PTFE”). In various embodiments, pivot joint  302  is disposed at or near the geometric center of pawl  202 . 
     With continued reference to  FIGS. 2A, 2B and 3A , pawl  202  comprises counterweight portion  208  and contact portion  210 . Pawl  202  may comprise a single integral piece comprising counterweight portion  208  and contact portion  210 . Counterweight portion  208  may be integral to pawl  202  and may be formed by any suitable means, for example, by forging, casting, stamping, negative manufacturing techniques, additive manufacturing techniques and/or other methods of manufacture. Counterweight portion  208  may be configured such that the center of mass of pawl  202  is more proximate a terminus of counterweight portion  208  than a terminus of contact portion  210 . Counterweight portion  208  may be configured to have a “scoop” or cut out and/or a portions of greater thickness and/or mass when compared with other portions of pawl  202 . 
     Torsion spring  304  may be disposed to exert a radial outward force upon pawl  202 . In that regard, torsion spring  304  exerts a rotational force on pawl  202  that tends to pivot pawl  202  about pivot joint  302  in a radially outward direction. Torsion spring  304  may be made from any suitable material, for example, stainless steel. 
     With reference to  FIG. 3B , upon rotation in clockwise direction  312 , contact portion  210  may be directed radially outward with respect to pawl carrier  206 . With reference to  FIG. 2B , as pawl carrier  206  rotates in counterclockwise direction  214  at an angular velocity below a predetermined angular velocity, each pawl may contact structures, such as a ratchet, disposed radially outward of pawl carrier  206 . In that regard, pawl  202  may periodically be deflected radially inward after contact with other contact structures. 
     In that regard, a stop pin may be disposed in an axial direction and provide a contact point for pawl  202  and contact portion  210  in particular, to prevent pawl  202  from contacting pawl carrier  206 . Thus, stop pin  204  is configured to interact with contact portion  210  in response to radially inward movement of pawl  202 . 
     The contact between pawl  202  and stop pin  204  may cause undesirable vibration. During rotation, it may be desirable to damp the oscillations of pawl  202  about pivot joint  302 . In that regard, with reference to  FIG. 2B , lubricating fluid stream  216  may be propelled radially outward of pawl carrier  206  and contact or otherwise interact with contact portion  210  of pawl  202 . Accordingly, after contact with other contact structures, pawl  202  may be sent radially inward toward stop pin  204 . Lubricating fluid stream  216 , traveling in a radially outward direction, may contact pawl  202  and oppose pawl  202 &#39;s radial inward motion. In such a manner and with momentary reference to  FIG. 3B , the oscillations of pawl  202  about pivot joint  302  tend to be damped. The flow rate of the lubricating oil, and the timing in which the oil is propelled radially outward, may be adjusted in accordance with a variety of factors. 
     With reference to  FIGS. 4A and 4B , cross sectional views  400  and  450  of pawl carrier  206  are shown along the line A-A′ shown in  FIG. 2B . Line A-A′ is disposed such that point A is forward of point A′. Pawl nut  218  is shown coupling low pressure turbine shaft (“LPT shaft”)  402  to pawl carrier  206 . LPT  402  drives rotation of pawl carrier  206 . Pawl  202  and contact portion  210  of pawl  202  is shown proximate pawl carrier  206 . Lubricating fluid system  406  is disposed radially inward of pawl carrier  206 . 
     Lubricating fluid system  406  may comprise any suitable system for the distribution and/or propulsion of a lubricating fluid. Lubricating fluid system  406  may comprise a pressurized system that allows a lubricating fluid to escape through one or more apertures (also referred to as orifices). In that regard, a pressurization system may impart pressurization to lubricating fluid system  406 . The increase in pressure in lubricating fluid system  406  may thus propel lubricating fluid from lubricating fluid system  406 , through an orifice, and away from the lubricating fluid system  406 . Pawl nut lubricating aperture  408 , for example, may also be part of lubricating fluid system  406 . Pawl nut lubricating aperture  408  may be configured to propel and/or distribute lubricating fluid to pawl nut  218 . 
     Lubricating fluid system radial aperture  404  is shown radially inward of pawl carrier  206 . Lubricating fluid system radial aperture  404  may comprise any suitable aperture or orifice to allow a lubricating fluid to be conducted away from lubricating fluid system  406 , for example, in a radially outward manner. As lubricating fluid stream  216  is propelled radially outward from lubricating fluid system  406 , lubricating fluid stream  216  passes through pawl nut radial aperture  410 . Pawl nut radial aperture  410  may be any aperture or orifice that may allow a lubricating fluid to travel radially outward. In like manner, lubricating fluid stream  216  passes through pawl carrier radial aperture  412 . Pawl carrier radial aperture  412  may be any aperture or orifice that may allow a lubricating fluid to travel radially outward. 
     Lubricating fluid stream  216  may then contact the contact portion  210  of pawl  202 . Lubricating fluid stream  216  travels in a radially outward direction. In that regard, lubricating fluid stream  216  may oppose the radially inward motion of pawl  202 , such as the radially inward motion caused by contact with a contact structure. 
     With reference to  FIG. 4B , stop pin  204  is shown in contact with contact portion  210  of pawl  202 . Pawl carrier radial aperture  412  is shown proximate to and radially inward of stop pin  204 . 
     In various embodiments, lubricating fluid damping may be of benefit with respect to counterweight portion  208  of pawl  202 . With reference to  FIG. 5 , cross sectional view  500  of pawl carrier  206  are shown along the line A-A′ shown in  FIG. 2B . Line A-A′ is disposed such that point A is forward of point A′. Lubricating fluid system  508  is disposed radially inward of pawl carrier  206 . 
     Lubricating fluid system  508  may comprise any suitable system for the distribution and/or propulsion of a lubricating fluid. Lubricating fluid system  508  may comprise a pressurized system that allows a lubricating fluid to escape through one or more apertures (also referred to as orifices). In that regard, a pressurization system may impart pressurization to lubricating fluid system  508 . The increase in pressure in lubricating fluid system  508  may thus propel lubricating fluid from lubricating fluid system  508 , through an orifice, and away from the lubricating fluid system  508 . 
     Lubricating fluid system radial aperture  506  is shown radially inward of pawl carrier  206 . Lubricating fluid system radial aperture  506  may comprise any suitable aperture or orifice to allow a lubricating fluid to be conducted away from lubricating fluid system  508 , for example, in a radially outward manner. As lubricating fluid stream  504  is propelled radially outward from lubricating fluid system  508 , lubricating fluid stream  504  passes through first pawl nut radial aperture  510  and second pawl nut radial aperture  512  in pawl nut  218 . First pawl nut radial aperture  510  and second pawl nut radial aperture  512  may be any aperture or orifice that may allow a lubricating fluid to travel radially outward. 
     Lubricating fluid stream  504  travels in a radially outward direction. Lubricating fluid stream  504  may branch into lubricating fluid stream  514  and lubricating fluid stream  516 . In that regard, lubricating fluid stream  514  may pass through second pawl nut radial aperture  512  and lubricating fluid stream  516  may pass through first pawl nut radial aperture  510 . 
     Lubricating fluid stream  514  and/or lubricating fluid stream  516  may then contact the counterweight portion  208  of pawl  202 . In that regard, lubricating fluid stream  514  and/or lubricating fluid stream  516  may oppose the radially inward motion of counterweight portion  208  of pawl  202 , such as the radially inward motion caused by the torsion spring  304 . 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.