Abstract:
A retainer for non-rotatably retaining a conduit member that extends through an opening in a casing wall. The retainer has an annular top wall that includes an inner periphery having inwardly extending projections to engage the outer surface of the conduit member. Additionally, the retainer includes a depending skirt that extends from the outer periphery of the top wall. A pair of outwardly extending straps extend from the skirt and include bolt holes for enabling the retainer to be bolted relative to the casing wall. The retainer limits axial outward movement of the conduit member and also diffuses and deflects any leakage air that passes around the conduit member to avoid impingement of the leakage air against the structural components and accessories that are positioned outside the engine casing.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to a retainer for non-rotatably retaining a conduit that extends through a casing or wall. More particularly, the present invention relates to a conduit retainer for use in a high temperature environment, such as adjacent a combustor of a gas turbine engine, that retains a conduit against rotation. 
     In gas turbine engines, several tubular conduits are provided that extend through an outer annular casing that surrounds the engine. Such conduits are provided for conveying fluids such as pressurized air, for cooling engine components subjected to very high temperatures, and oil, for lubricating bearings supporting rotating components of the engine. Because of vibrations that are encountered during engine operation, it is desirable to restrain such conduits from rotational motion about their own axes to retain them in the desired positions. Additionally, there is a possibility of leakage of high pressure air or gas from within the engine at the conduit-casing junction. Such leakage gas can impinge upon the adjacent structure that surrounds the engine, such as airframe and engine nacelle structural elements. And because some of the conduits extend through the engine casing at points where the air or gas within the interior of the casing is at a relatively high temperature, such as the combustor portion of the casing or the compressor discharge portion of the casing, where internal temperatures can be of the order of about 1,000° F. or so, it is desirable to deflect such leakage flow laterally, away from the structure that surrounds the engine casing. 
     One form of retainer that has been utilized in the past is an annular disk having serrations around its inner periphery and including a pair of outwardly extending tabs to secure the retainer to the engine casing. The serrations engage the periphery of the conduit to prevent rotation of the conduit about its own axis. However, because of the varying forces that are imposed on such conduits during engine operation and during aircraft maneuvers, including vibratory forces, the stresses to which the conduit retainers are subjected include cyclic stresses induced by vibrations, and they sometimes result in fatigue-induced cracking of the annular disk portion of the retainer. 
     It is therefore desirable to provide a conduit retainer that non-rotatably supports the conduit, that serves to diffuse or deflect the leakage air that exits at the conduit-casing junction, and also to withstand the cyclic stresses that are encountered during engine operation. 
     SUMMARY OF THE INVENTION 
     Briefly stated, in accordance with one aspect of the present invention, a retainer is provided for retaining a conduit member that extends through a wall. The retainer includes an annular top wall having an outer edge and having an opening that includes a plurality of contact surfaces for cooperative engagement with a conduit member to be retained. A depending skirt extends from the outer edge at one face of the top wall for a predetermined length and terminates at a free end. At least two circumferentially-spaced legs extend from the free end of the depending skirt, and each leg carries a radially-outwardly-extending tab. Each tab includes a bolt opening for receiving a connecting bolt for attaching the retainer to the wall through which the conduit member extends. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a longitudinal, cross-sectional view of an aircraft gas turbine engine. 
     FIG. 2 is a fragmentary, cross-sectional view taken through the downstream portion of an axial-flow compressor and the downstream combustor section of a gas turbine engine of the type shown in FIG.  1 . 
     FIG. 3 is a fragmentary, exploded view showing the several components that are provided at a point where a conduit extends through the combustor casing shown in FIG.  2 . 
     FIG. 4 is an enlarged, fragmentary, cross-sectional view of the conduit and casing showing the several conduit connection components shown in FIG. 3 in their assembled condition. 
     FIG. 5 is a fragmentary top view of the conduit and casing connection arrangement shown in FIGS. 3 and 4. 
     FIG. 6 is a top view of one embodiment of an improved conduit retainer. 
     FIG. 7 is a side elevational view of the retainer shown in FIG. 6, taken along the line  7 — 7  thereof. 
     FIG. 8 is a side elevational view of the retainer shown in FIG. 6, taken along the line  8 — 8  thereof. 
     FIG. 9 is a cross-sectional view of the retainer shown in FIG. 6, taken along the line  9 — 9  thereof. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and particularly to FIG. 1 thereof, there is shown in diagrammatic form an aircraft turbofan engine  10  having a longitudinal axis  11 , and including a core gas turbine engine  12  and a fan section  14  positioned upstream of the core engine. Core engine  12  includes a generally tubular outer casing  16  that defines an annular core engine inlet  18  and that encloses and supports a low pressure booster  20  for raising the pressure of the air that enters core engine  12  to a first pressure level. A high pressure, multi-stage, axial-flow compressor  22  receives pressurized air from booster  20  and further increases the pressure of the air. The pressurized air flows to a combustor  24  in which fuel is injected into the pressurized air stream, and the fuel-air mixture is ignited to raise the temperature and energy level of the pressurized air. The high energy combustion products flow to a first turbine  26  for driving compressor  22  through a first drive shaft  28 , and then to a second turbine  30  for driving booster  20  through a second drive shaft  32  that is coaxial with first drive shaft  28 . After driving each of turbines  26  and  30 , the combustion products leave core engine  12  through an exhaust nozzle  34  to provide propulsive jet thrust. 
     Fan section  14  includes a rotatable, axial-flow fan rotor  36 . An annular fan casing  38  surrounds fan rotor  36  and is supported from core engine  12  by a plurality of substantially radially-extending, circumferentially-spaced support struts  44 . Fan rotor  36  carries a is plurality of radially-extending, circumferentially spaced fan blades  42 . Fan casing  38  extends rearwardly from fan rotor  36  over an outer portion of core engine  12  to define a secondary, or bypass airflow conduit. A casing element  39  that is downstream of and connected with fan casing  38  supports a plurality of fan stream outlet guide vanes  40 . The air that passes through fan section  14  is propelled in a downstream direction by fan blades  42  to provide additional propulsive thrust to supplement the thrust provided by core engine  12 . 
     FIG. 2 shows the downstream, high-pressure section of an axial flow compressor  50  and combustor  52  into which the compressed, high-pressure air is introduced. Immediately downstream of combustor  52  is a high-pressure turbine  54 . Compressor  50  includes an outer, annular casing  56  having a radially-outwardly-extending end flange  58 . Combustor  52  includes an annular, outer combustor casing  60  having an end flange  62  that has a shape that corresponds with that of compressor end flange  58 . Flanges  58  and  62  are bolted together with a plurality of circumferentially-distributed connecting bolts (not shown) to confine the high-pressure air and the high-pressure and high-temperature combustion gases within the engine outer casing. In that regard, the temperature of the high-pressure air that exits from the compressor and enters the combustor is of the order of about 1,000° F. or so, depending upon the temperature of the air at the compressor inlet and also depending upon the compressor pressure ratio and efficiency. 
     Several air and oil lines pass through the engine casing. One such line, oil line  64 , is shown in FIG. 2, and the ensuing description will be understood to be applicable to other air and oil lines that pass through the engine casing. Oil line  64  passes outwardly through the engine at the combustor casing and extends from a point within the casing to a point without the casing to convey lubricating oil to an engine drive shaft support bearing  66  that is positioned interiorly of combustor  52 . 
     FIGS. 3,  4 , and  5  show various views of a portion of combustor casing  60  and the components that surround and support oil line  64 . As shown in FIG. 3, combustor casing  60  includes an opening  68  through which oil line  64  passes, and a surrounding mounting boss  70  for receiving the several elements of the oil line supporting structure. An end of oil line  64  is connected to one end of a tubular coupling  72 , such as by welding, or the like. Coupling  72  includes a first, inner piston  74  that carries an inner piston ring  76  at its periphery. Inner piston  74  is slidably received within a tubular conduit member  78  for axial sliding movement along the inner surface  80  of conduit member  78 . At its outer periphery conduit member  78  carries an outer piston  82  that includes a peripherally-positioned outer piston ring  84 . 
     As best seen in FIG. 4, conduit member  78  includes external threads  77  at its innermost end, and is threadedly received in a correspondingly internally threaded opening in diffuser  79 . Carried on the outer surface of conduit member  78  and spaced axially from outer piston  82  is a radially-outwardly-extending stop ring  86  that engages a radially-extending stop surface  88  carried by diffuser  79  and spaced interiorly of combustor casing  60 . 
     An annular seal housing  90  is positioned in surrounding relationship with conduit member  78 . Because of the effects of thermal expansion from a cold startup to operating temperature, there is relative movement in the axial direction of the engine between combustor casing  60  and diffuser  79 . To allow for such axial movement, which can be of the order of about 0.020 inches or so, seal housing  90  has an inner diameter that is slightly larger than the outer diameter of outer piston  82  of conduit member  78 . The position of the parts as shown in FIG. 4 is for a cold condition, before thermal expansion has occurred, and the forwardmost edge of conduit member is in contact with the forwardmost portion of inner surface  80 . When the parts reach their normal operating temperatures, conduit member  78  will have moved aft a slight distance, because of differential thermal expansion of combustor casing  60  and diffuser  79 , so that conduit member  78  is substantially concentric with seal housing  90 . During that movement, which is in axial direction relative to the longitudinal axis of the engine, piston ring  84  serves to provide a seal to minimize passage of air between conduit member  78  and seal housing  90 . Seal housing  90  also includes an inner annular recess  92  to receive an annular sealing ring  94  that provides a seal between seal housing  90  and the outer surface of mounting boss  70 . 
     Referring now to FIGS. 4 and 5, positioned adjacent the outermost end  96  of conduit member  78  is a conduit member retainer  98  in the form of an annular ring. Retainer  98  is adapted to engage the outer peripheral surface of conduit member  78  to prevent it from rotating relative to diffuser  79  and thereby preventing it from becoming unthreaded from the diffuser. As will be apparent from FIG. 4, conduit member  78  allows oil line  64  and its interconnected inner piston  74  to move axially within conduit member  78 , to allow for the effects of thermal expansion and for the effects of forces that are imposed on oil line  64  during engine operation and during aircraft maneuvers. 
     The structure of retainer  98  is shown in greater detail in FIGS. 6 through 9. As best seen in FIG. 6, retainer  98  includes an annular top wall  102  that includes an opening  104  having a periphery defined by a plurality of substantially equally-spaced, radially-inwardly-extending projections  106 . Projections  106  can be of any desired shape, including the triangular form shown in FIG.  6 . In that regard, projections  106  are intended to permit engagement of retainer  98  with the outer periphery of conduit member  78  to prevent rotation of conduit member  78  about its own axis. For a conduit member  78  such as that shown in FIG. 3, having a hexagonal external formation, opening  104  in retainer top wall  102  can be a hexagonal opening. However, when opening  104  in retainer  98  and the portion of the sidewall of conduit member  78  that retainer  98  is intended to engage are the same configuration, it is necessary that the parts be properly aligned with respect to each other during assembly. To avoid that necessity, the form of opening  104  of retainer  98  as shown in FIG. 6, having a plurality of small, circumferentially-distributed projections, is desirable in that it does not require precise alignment between opening  104  and conduit member  78  during assembly. 
     Because of the rearward axial movement of conduit member  78  relative to combustor casing  60  from engine startup to operating temperatures, opening  104  of retainer  98  can be eccentrically positioned relative to top wall  102  to accommodate the distribution of stresses thereby imposed on the retainer. And retainer  98  can plastically deform to a slight degree during such movement. In that regard, the width of top wall  102  in a radial direction relative to opening  104  can be larger on the aft side of the retainer, as it is connected with the combustor casing, than on the forward side. 
     As best seen in FIGS. 7 through 9, top wall  102  has an outer edge  108  from which an annular sidewall or skirt  110  depends. As shown, skirt  110  extends in a direction that is substantially perpendicular to the plane in which top wall  102  lies. Additionally, skirt  110  can extend around the entire outer periphery of top wall  102 , if desired. Skirt  110  is includes a pair of arc-shaped, circumferentially spaced, axial extensions or legs  112  that extend from skirt  110  and that have a predetermined length. Each of legs  112  terminates in and carries a radially-outwardly-extending connection tab  114 , as best seen in FIG. 6, and each connection tab  114  includes an elongated opening  116  to receive a connecting bolt (not shown) for connecting tabs  114  to seal housing  90 , as shown in FIGS. 4 and 5. Although only two tabs  114  are shown, if desired additional tabs, such as four, for example, to correspond with the four bolt holes in seal housing  90 , can also be provided. 
     Legs  112  extend substantially perpendicularly relative to top wall  102 , and they can have a length in the axial direction of retainer  98  that is greater than the axial length of skirt  110 . The ratio of the axial length of skirt  110  relative to the axial length of the skirt plus the axial length of legs  112  can be of the order of about 0.45, and the ratio of the axial length of skirt  110  to the radial width of annular top wall  102  can range from about 0.5 to about 2.0. Those size relationships for the retainer elements can provide the desired resistance to cracking of top wall  102  when subjected to cyclic stresses imposed during engine operation. 
     During engine operation retainer  98 , by virtue of its engagement with conduit member  78 , provides secondary rotation retention of conduit member  78  relative to mounting boss  70 . However, it is also desirable that retainer  98  have sufficient compliance in the axial direction to accommodate limited axial movement of conduit member  78  relative to the longitudinal axis of the engine. Such limited axial movement can be of the order of about 0.020 inches or so. And because the axial movement of tubular coupling  72  can be of a cyclic nature, it is also desirable that retainer  98  have a resonant frequency that is greater than about 590 Hz, and that it not have a resonant frequency within the range of from about 0 to about 590 Hz, which is a typical vibratory frequency range that can be encountered in gas turbine engines. 
     Because conduit member  78  is slidably carried within seal housing  90  and the seal therebetween is provided by a piston ring, it is possible for some leakage of heated air to occur between those elements. In that regard, the environment within combustor casing  60  and adjacent its inner surface is at a high pressure, by virtue of the work done by compressor  50  in compressing the incoming air, and it is also at a relatively high temperature, of the order of about 1,000° F. or so. And because the engine is carried within an airframe, or within an engine nacelle, and aircraft structural components, hydraulic lines, and the like can be positioned outside the engine, it is desirable to diffuse any such leakage air to reduce its velocity in the axial direction of conduit member  78  so it does not impinge on surrounding airframe structural and accessory elements with a large force. Additionally, it is desirable to attempt to deflect any such leakage air so it is not directed at the airframe-carried elements. In the retainer structure shown in FIGS. 6 through 9, at least a portion of the leakage air is turned 180° by retainer top wall  102  and by skirt  114 , to flow in a reverse axial direction and toward the combustor casing, to prevent the high temperature leakage air from impinging against adjacent air frame structural elements or accessories that should not be subjected to high temperatures. 
     The size of opening  104  of retainer  98  can be enlarged if it is desired to minimize the imposition on retainer  98  of loads in the axial direction of the engine resulting from movement of conduit member  78  relative to seal housing  90 . In that instance opening  104  can have a size that corresponds with the outer periphery of conduit member  98  with which the retainer is to engage, plus an amount that corresponds with the distance that conduit member  78  is expected to move relative to the retainer. Thus, the centerline of opening  104  will be eccentric to the centerline of conduit member  78 . Accordingly, retainer  98  will engage the forwardmost surface of conduit member  78  when the engine is in a cold condition and it will engage the aftmost surface of the conduit member when the engine has reached an equilibrium operating condition and conduit member  78  has shifted from its initial position relative to retainer  98  to its final position, by virtue of the differential thermal expansion of the several parts of the conduit connection assembly and related engine parts. 
     The retainer structure herein illustrated and described provides the desirable qualities discussed above. It prevents rotation of the conduit member and, by virtue of its close engagement with the periphery of the conduit member, it serves to diffuse the leakage of high pressure, high temperature air and to deflect and turn it away from the adjacent airframe structural components and accessories that are outside the engine casing. 
     Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. Accordingly, it is intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.