Patent Publication Number: US-2023143483-A1

Title: Piston seal assembly guards and inserts for seal groove

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of, and claims priority to, and the benefit of, U.S. application Ser. No. 16/883,442, filed May 26, 2020, and entitled “PISTON SEAL ASSEMBLY GUARDS AND INSERTS FOR SEAL GROOVE,” which is incorporated by reference herein in its entirety for all purposes. 
    
    
     FIELD 
     The disclosure relates generally to vehicles and machinery and, more specifically, to bearing carries and systems for turbine engines. 
     BACKGROUND 
     Gas turbine engines are known to include piston seal assemblies between various components, for example, to inhibit pressure loss between compartments or provide fluid sealing between compartments. In operation, piston seal assemblies may tend to degrade over time. For example, operational conditions of the gas turbine engine may tend to induce fretting at the loaded face of a seal groove. In this regard, piston seal assembly performance may tend to be reduced over time in response to fretting and/or other wear of the piston seal assembly features. 
     SUMMARY 
     In various embodiments, a method of repairing a piston seal assembly is disclosed comprising removing worn material from a piston seal groove to generate a worked seal groove, applying a groove buildup member to the worked seal groove, and disposing a seal member proximate the groove buildup member. 
     In various embodiments, the method includes securing the groove buildup member to the worked seal groove. In various embodiments, the method includes disposing the seal member within the groove buildup member. In various embodiments, the groove buildup member is a guard type member. In various embodiments, the groove buildup member is an insert type member. In various embodiments, the groove buildup member is a sectioned insert type member. In various embodiments, the groove buildup member comprises circumferentially segmented sections. In various embodiments, the groove buildup member is circumferentially continuous. 
     In various embodiments, a gas turbine engine is disclosed comprising a compressor section configured to compress a gas, a combustor section aft of the compressor section and configured to combust the gas, and a piston seal assembly comprising, a worked seal groove, a groove buildup member secured to the worked seal groove, and a seal member disposed proximate the groove buildup member. 
     In various embodiments, the seal member is disposed within the groove buildup member. In various embodiments, the groove buildup member is a guard type member. In various embodiments, the groove buildup member is an insert type member. In various embodiments, the groove buildup member is a sectioned insert type member. In various embodiments, the groove buildup member comprises circumferentially segmented sections. In various embodiments, the groove buildup member is circumferentially continuous. 
     In various embodiments, and article of manufacture is disclosed comprising a groove buildup member configured to be secured to a worked seal groove of a piston seal assembly, wherein the groove buildup member comprises one of a guard type member, an insert type member, or a sectioned insert type member each respectively configured to engage with a surface of the worked seal groove. 
     In various embodiments, the guard type member is further configured to interface with a reduced wall of the piston seal assembly and comprises an inner guard and an outer guard each joined at a distal end by an orthogonal web, wherein the inner guard is relatively longer than the outer guard. In various embodiments, the insert type member is configured to be disposed within the worked seal groove and comprises a forward wall, an aft wall, and a base web joining the forward wall and the aft wall and mutually orthogonal thereto. In various embodiments, the sectioned insert type member is relatively L-shaped and defined by a leg member and an orthogonal foot member extending at a distal end of the leg member. In various embodiments, the groove buildup member comprises circumferentially segmented sections. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings. 
    
    
     
       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 disclosures, 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 an exemplary gas turbine engine, in accordance with various embodiments; 
         FIG.  2 A  illustrates a piston seal assembly in a gas turbine engine, in accordance with various embodiments; 
         FIG.  2 B  illustrates a worn seal groove of a piston seal assembly, in accordance with various embodiments; 
         FIG.  3 A  illustrates a machining step of a repair method for a piston seal assembly, in accordance with various embodiments; 
         FIG.  3 B  illustrates the outcome of a machining step of a repair method for a piston seal assembly; 
         FIG.  4 A  illustrates groove buildup members of a piston seal assembly, in accordance with various embodiments; 
         FIG.  4 B  illustrates a reworked piston seal assembly including a first groove buildup member, in accordance with various embodiments; 
         FIG.  4 C  illustrates a reworked piston seal assembly including a second groove buildup member, in accordance with various embodiments; 
         FIG.  4 D  illustrates a reworked piston seal assembly including a third groove buildup member, in accordance with various embodiments; 
         FIG.  4 E  illustrates a reworked piston seal assembly including a third groove buildup member, in accordance with various embodiments; 
         FIG.  4 F  a groove buildup member, in accordance with various embodiments; and 
         FIG.  4 G  a groove buildup member, in accordance with 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 disclosures, 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 disclosures. 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. 
     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 . In operation, fan section  22  can drive air along a bypass flow-path B while compressor section  24  can drive air 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 turbojet engines, a low-bypass turbofans, a high bypass turbofans, or any other gas turbine known to those skilled in the art. 
     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 one or more bearing systems  38  (shown as bearing system  38 - 1  and bearing system  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  (also referred to a low pressure compressor) 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 compressor (“HPC”)  52  (e.g., a second compressor section) and high pressure (or second) turbine section  54 . A combustor  56  may be located between HPC  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 HPC  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. Low pressure turbine  46 , and high pressure turbine  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, the bypass ratio of gas turbine engine  20  may be greater than about six (6). In various embodiments, the bypass ratio of gas turbine engine  20  may be greater than ten (10). 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. Geared 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. 
     In various embodiments, the next generation of turbofan engines may be designed for higher efficiency which is associated with higher pressure ratios and higher temperatures in the HPC  52 . These higher operating temperatures and pressure ratios may create operating environments that may cause thermal loads that are higher than the thermal loads encountered in conventional turbofan engines, which may shorten the operational life of current components. 
     In various embodiments, HPC  52  may comprise alternating rows of rotating rotors and stationary stators. Stators may have a cantilevered configuration or a shrouded configuration. More specifically, a stator may comprise a stator vane, a casing support and a hub support. In this regard, a stator vane may be supported along an outer diameter by a casing support and along an inner diameter by a hub support. In contrast, a cantilevered stator may comprise a stator vane that is only retained and/or supported at the casing (e.g., along an outer diameter). 
     In various embodiments, rotors may be configured to compress and spin a fluid flow. Stators may be configured to receive and straighten the fluid flow. In operation, the fluid flow discharged from the trailing edge of stators may be straightened (e.g., the flow may be directed in a substantially parallel path to the centerline of the engine and/or HPC) to increase and/or improve the efficiency of the engine and, more specifically, to achieve maximum and/or near maximum compression and efficiency when the straightened air is compressed and spun by rotor  64 . 
     In various embodiments and with additional reference to  FIGS.  2 A and  2 B , gas turbine engine  20  includes one or more piston seal assemblies  200 . Piston seal assembly  200  is illustrated in cross section through the X-Y plane and may comprise a portion of a case  202  such as, for example, a high pressure compressor case, a combustor case, a mid turbine frame, and/or the like. The case  202  may extend axially along the engine  20  axis A-A′. The assembly  200  comprises a forward seal wall  206  and an aft seal wall  208 . The seal walls  206  and  208  extend radially (along the Y-axis) from the case  202 . In various embodiments, each of the seal walls  206 ,  208  may be orthogonal to the case  202 . The seal walls  206 ,  208  define a seal groove  204  axially therebetween. The seal groove  204  comprises a forward face  212 , an aft face  216 , and a base  214 . A seal member  210  is seated toward the base  214  in the seal groove  204  and retained axially relatively between the forward face  212  and the aft face  216 . In various embodiments and in operation of the gas turbine engine  20 , the seal member  210  may be loaded relatively toward the forward face  212  as indicated by arrow F. In response, the seal groove may  204  may experience wear, fretting, and/or the like within the groove  204  at the forward face  212  and the base  214 . In various embodiments and in response to seal groove  204  experiencing wear in the forwarded loaded condition, the groove surface may be eroded to generate a forward worn face  212 ′ and a worn base  214 ′. Such wear and/or erosion of the seal groove  204  tends to degrade performance of the piston seal assembly  200 , for example, by allowing gasses to bypass the seal member  210  along the worn surfaces (forward face  212 ′, base  214 ′). 
     In various embodiments and with additional reference to  FIG.  3 A , a tool  300  is applied to the seal groove  204 . In various embodiments, the tool  300  may be a machining tool applied directly to the worn surfaces ( 212 ′,  214 ′). In various embodiments, the tool  300  may be an ablative tool such as, for example, a laser. Tool  300  operations continue until the entire worn surface of the seal groove  204  is removed (e.g., by machining, ablation, polishing, lapping, etc.) as shown in  FIG.  3 B . In various embodiments and with additional reference to  FIG.  3 B , the seal groove  204  has been enlarged by the tool  300  operation to generate a worked seal groove  204 ′. In like regard, the worked seal groove  204 ′ may be further defined by a reduced wall  206 ′ (as illustrated, a reduced forward wall) which is thinned by tool  300  operations. In various embodiments, the worked seal groove  204 ′ may not provide adequate retention for the seal member  210 . 
     In various embodiments and with additional reference to  FIG.  4 A , one or more groove buildup members  400  such as, for example, a first groove buildup member  402 , a second groove buildup member  404 , and/or a third groove buildup member  406  may be inserted (e.g., along arrows) into the worked seal groove  204 ′ and/or over the reduced wall  206 ′. In various embodiments, the buildup member  400  may be manufactured from the same parent material, a different material, a ceramic material, or a coated material. In various embodiments, a groove buildup member  400  may be formed for an appropriate metal or other material which is similar to the parent material (such as, for example, steel, stainless steel, aluminum alloy, titanium alloy, nickel alloy, and/or the like) and which provides wear characteristics equivalent or superior to the material of the case  202 . The groove buildup member  400  may be secured to the worked seal groove  204 ′ by any suitable process such as, for example, brazing, press fitting, welding, bonding, crimping, staking, a retention feature (e.g., undercutting) and/or the like. 
     In various embodiments, the first groove buildup member  402  may be a guard type member configured to interface with the reduced wall  206 ′. The guard type member comprises an inner guard  408  and an outer guard  410  joined at a distal end by an orthogonal web  412 . The inner guard  408  is configured to be disposed within the worked seal groove  204 ′ and may thereby be relatively radially (along the Y-axis) longer than the outer guard  410 . Stated another way, the outer guard  410  may be shorter than the inner guard  408 . As shown in  FIG.  4 B , the first groove buildup member  402  may be coupled to the reduced wall  206 ′ and the seal member  210  may be disposed in the worked seal groove  204 ′ to complete the rebuild of the piston seal assembly  200 . 
     In various embodiments, the second groove buildup member  404  may be an insert type member comprising a forward wall  414 , an aft wall  416 , and a mutually orthogonal base web  418  joining the forward wall  414  and the aft wall  416 . The insert type member is configured to be disposed within the worked seal groove  204 ′. As shown in  FIG.  4 C , the second groove buildup member  404  is inserted into the worked seal groove  204 ′. The forward wall  414  and the aft wall  416  are contacted, respectively, with the reduced wall  206 ′ and the aft seal wall  208 . In like regard, the base web  418  is contacted with the base of the worked seal groove  204 . The seal member  210  is disposed within the second groove buildup member  404  to complete the rebuild of the piston seal assembly  200 . 
     In various embodiments, the third groove buildup member  406  may comprise a sectioned insert type member including a forward section  420  and an aft section  422 . Each section may be relatively L-shaped and defined by a leg member  424  and an orthogonal foot member  426  which extends at a distal end of the leg member  424 . Each section ( 420 ,  422 ) is configured to be disposed within the worked seal groove  204 ′ and may be configured to retain the seal member  210  relatively therebetween as shown in  FIG.  4 D . In various embodiments as shown in  FIG.  4 E , a rework procedure may call for only one section of a sectioned insert type member to be inserted into the worked seal groove  204 ′. For example, where the reduced wall  206 ′ is generated from the forward seal wall  206 , the forward section  420  of the third groove buildup member  406  may be inserted into the worked seal groove  204 ′. In various embodiments, the forward section  420  may comprise an elongate foot  426 ′ configured to extend across the entirety of the base of the worked seal groove  204 ′. The seal member  210  is disposed within the respective section (as illustrated, the forward section  420 ) of third groove buildup member  406  to complete the rebuild of the piston seal assembly  200 . 
     In various embodiments and with additional reference to  FIGS.  4 F and  4 G  groove buildup member  400  is viewed along the Z-axis through the Y-Z plane. In various embodiments, a groove buildup member  400  may be continuous about a center axis C (e.g, axis A-A of engine  20 ) or may be formed of a plurality of circumferentially segmented sections  400 S (i.e., arcuate segments) all centered about the center axis C. 
     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 disclosures. 
     The scope of the disclosures 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. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “an example embodiment”, 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 embodiment 
     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 is intended to invoke 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.