Patent Publication Number: US-2018030856-A1

Title: Liner Element of a Turbomachine and Correspoding Connection Assembly

Description:
This claims the benefit of German Patent Application DE 102016213813.8, filed Aug. 1, 2016 and hereby incorporated by reference herein. 
     The present invention relates to a liner element, in particular a heat shield element or casing element, of a turbomachine, in particular a gas turbine, including: a fastening portion having at least one bore through which a connection unit having, in particular a pin-type or bolt-type form, is introducible along a bore axis; a liner portion that adjoins the fastening portion; the fastening portion and the liner portion being formed in one piece, and having an annular or ring segment shape. 
     BACKGROUND 
     When liner elements formed, in particular as thin-walled components, preferably of a sheet metal, are fastened by rivets or screws, the problem regularly arises that, on the one hand, substantial vibrational stresses and, on the other hand, significant temperature fluctuations and mechanical stresses can occur. Accordingly, the fastening used for these liner elements should have very low tolerances, be able to withstand high loads and compensate for large thermal expansions. Therefore, very high manufacturing accuracies are required. Disk springs are typically used to compensate for manufacturing tolerances. However, they take up installation space and greatly limit the material selection. 
     Thermal expansions of liner elements can often only be compensated by using what are commonly known as sliding fits. They must have a certain minimum clearance to allow for a shifting of components relative to each other in response to temperature fluctuations. However, this leads to a less precise fastening of components so that they can be excited to vibrate. Such vibration increases wear and can also lead to failure of such a component or liner element. 
     A liner element in the form of a heat shield is known from World Patent Application WO 2015/102702 A, specifically from  FIG. 2 . 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a liner element that will withstand substantial vibrational and mechanical stresses and, at the same time, compensate for thermal expansions. 
     In the case of a liner element, it is achieved, in particular by providing the bore in a depression formed in the fastening portion, the depression being essentially configured concentrically about the bore. 
     The annular or ring segment-shaped embodiment of the liner element is in relation to the machine axis of the turbomachine. The concentric embodiment of the depression refers to a bore axis that extends centrally through the bore. Relative to the turbomachine, the bore axis may extend parallel to the axial direction thereof or parallel to the radial direction or also obliquely relative to these two directions. 
     An integrally formed resilient element is created by providing a depression in the fastening portion. Accordingly, installing such a liner element reduces the need for component parts. In particular, fewer or no disk springs are needed. The resilient effect thereof makes it possible for the depression to absorb vibrations, without the vibrations inducing a significant movement of connected components relative to each other. This reduces the wear the liner element, respectively a part connected thereto, is subject to. 
     The depression may have a crimped form. However, such a crimp does not have a groove-like or distinctly elongated shape, but is configured to be circular, elliptical or oval. 
     The bore may have a circular or elongated hole shape. In the case of a circular bore, which may also be referred to as a round hole, the connection unit provides a close fit for the liner element on another component. When the bore has an elongated hole shape, the liner element is movable therealong relative to the connection unit, making it possible to compensate for thermal expansions, in particular. An elongated bore may provide a sliding fit. 
     In relation to the bore axis, the depression may have an axial depth that corresponds approximately to 0.9 to 1.5 times a thickness of the fastening portion. This makes it possible to provide a depression that takes up little installation space. Furthermore, depending on the depth, the potential spring deflection may be adjusted, in particular along the bore axis. 
     The depression may have a rim portion that surrounds the bore, the rim portion being essentially formed parallel to a surface of the fastening portion surrounding the depression. The purpose of the rim portion, in particular is to provide a bearing surface that extends around the bore and enables the fastening portion to be supported on another component. 
     The liner element may include at least two bores, each having a depression; in the area of the bores, the fastening portion having a height extending in a surface plane of the fastening portion that is greater than the height between two adjacent bores. In relation to an annular or ring segment-shaped embodiment, a plurality of circumferentially spaced bores may be provided in the fastening portion. In this context, adjacent bores may have the same shape or differ from one another. For example, a bore may be circularly shaped as a close fit, and one or a plurality of adjacent bore(s) may be elongated hole-shaped as sliding fit(s). 
     The liner element may be made of a sheet metal or of carbon fiber-reinforced plastic. The depression may thereby have two curvatures in different directions. Thus, extending from a surface of the fastening portion, the depression may be formed in a type of S-shaped sequence of two curvatures, so that the rim portion already mentioned above resides on a different level than the surface of the fastening portion. In the case of a sheet metal, the bore may be produced by deep drawing. 
     The present invention also relates to a connection assembly in a turbomachine, in particular in a gas turbine between a liner element described above and another component of the turbomachine, a connection unit joining the component and the liner element to one another in the area of the at least one bore of the fastening portion of the liner element. The fastening portion is thereby configured more closely to the further component in the area of the depression around the bore than outside of the depression, and at least one washer, which is in contact with the fastening portion, is configured around the connection unit. 
     Two washers, between which the fastening portion is accommodated, may be configured around the connection unit, one of the washers engaging on the further component. 
     The connection unit may be a riveted joint or a bolt connection, in particular a bolt-and-nut connection. 
     A spacer sleeve may be configured around the connection unit in the area of the depression, on the side of the fastening portion facing away from the further component. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be explained exemplarily in the following with reference to the enclosed figures and without being limited thereto. 
         FIG. 1  shows a specific embodiment of a liner element in a simplified and schematic perspective view, in particular from an oblique front view oriented towards an installation position in a gas turbine. 
         FIG. 2  shows the liner element of  FIG. 1  in another simplified and schematic perspective view, in particular from an oblique rear view oriented towards an installation position in the gas turbine. 
         FIGS. 3A and 3B  show a plan view and a sectional view through a depression of the liner element. 
         FIG. 4  shows a sectional view of a connection assembly having a liner element according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a liner element  10  essentially having an annular or ring segment shape. In the present example, liner element  10  is a protective heat shield of a gas turbine in the turbine section thereof. However, the liner element is not limited to a protective heat shield, but may also be a different component of a gas turbine, such as a covering or encasing liner element, for example, a casing part or the like. 
     Liner element  10  includes a fastening portion  12  in which a plurality of bores  14 - 1 ,  14 - 2  are provided. Adjoining fastening portion  12  is a liner portion  16 . Fastening portion  12  and liner portion  16  are joined together in one piece. In the present specific embodiment, fastening portion  12  extends along circumferential direction CD and in radial direction RD in relation to the installed position thereof in a gas turbine, these directional indications being in relation to a machine axis of the gas turbine. Liner portion  16  may have a radially inner portion  18  and a radially outer portion  20  that are joined to one another by an intermediate portion  22 . The liner portion extends along circumferential direction CD and axial direction AD, so that it is essentially oriented orthogonally to fastening portion  12 . In the area of bores  14 - 1 ,  14 - 2 , a rim  13  of fastening portion  12  extends radially further outwardly than between two adjacent bores. In other words, the height of fastening portion  12  is variable and is greater in the region of bores  14 - 1 ,  14 - 2  than in the region between two bores  14 - 1 ,  14 - 2 . 
     It should be appreciated, however, that the fastening portion does not necessarily need to be oriented as shown in  FIGS. 1 and 2 . Rather, the fastening portion may also extend obliquely to radial direction RD and to the axial direction. It is also conceivable that the fastening portion extends along axial direction AD and circumferential direction CD. Also, the orientation of liner portion  16  is not limited to the representation of  FIGS. 1 and 2 . A continuous liner portion that extends obliquely to axial direction AD, for example, and forms a type of cone is also conceivable, for example. 
     In the present example, bore  14 - 1  is formed as a circular round hole. Bores  14 - 2  are formed as elongated holes. Respective depressions  24 - 1  and  24 - 2  are formed in fastening portion  12  about bores  14 - 1  and  14 - 2 . Depressions  24 - 1 ,  24 - 2  thereby have a rim portion  26  surrounding respective bore  14 - 1 ,  14 - 2 . Bores  14 - 1 ,  14 - 2  are adapted for receiving a connection unit, such as a bolt, a screw, in particular also a bolt-and-nut connection or a rivet. 
     From the plan view in accordance with  FIG. 3A ) and the corresponding sectional view of  FIG. 3B ), a bore  14 - 2  is shown exemplarily in the form of an elongated hole. It may thereby be elongated hole  14 - 2  shown in  FIG. 1  to the left of bore  14 - 1 , for example. Bore  14 - 2  has a bore axis BA which essentially passes centrally through bore  14 - 2 . The bore axis essentially corresponds to an axis of a connection unit to be inserted into bore  14 - 2 . In  FIG. 3A , depression  24 - 2  is indicated in the form of concentric lines; these lines representing a type of contour lines. Extending from a front surface  28 , which essentially lies in a surface plane of fastening portion  12  (corresponds to the drawing plane in  FIG. 3A ), depression  24 - 2  has a first, in particular convex curvature  30 , and a second, in particular concave curvature  32 . Bore  14 - 2  is bounded by rim portion  26 , which, in relation to bore axis BO, radially inwardly adjoins second curvature  32 . 
     Rim portion  26  is configured to be essentially parallel to surface  28  of fastening portion  12 . In addition, by side  34  thereof which faces away from surface  28  and may also be referred to as rear surface of rim portion  26 , rim portion  26  is adapted to rest against a component to be connected, such as a washer, a casing component or the like. 
     In the stress-relieved state, i.e., a state in which fastening portion  10  is not yet fastened, depression  24 - 2  has a depth DD that preferably has a distance from surface  28  that corresponds approximately to 0.9 to 1.5 times material thickness MT, in particular the plate thickness of liner element  10 . In relation to bore axis BA, bore  14 - 2  extends in a first direction D 1 , which corresponds to circumferential direction CD in the specific embodiment when liner element  10  is properly installed. In addition, bore  14 - 2  extends in a second direction D 2  that is orthogonal to first direction D 1  and corresponds to radial direction RD in the specific embodiment when liner element  10  is properly installed. In first direction D 1 , bore  14 - 2  has a width B and, in second direction D 2 , a height H. In addition, in first direction D 1 , depression  24 - 2  has a width DW and, in second direction D 2 , a height DH. 
     In the case of an elongated hole, the ratio of width W to height H (W/H) of bore  14 - 2  is greater than one, and may preferably have a value of up to approximately two. 
     In the case of an elongated hole, the ratio of width W of depression  24 - 2  to width DW of bore  14 - 2  is greater than one, and may preferably have a value of up to approximately two. 
     The just aforementioned with reference to  FIGS. 3A ) and  3 B) for an elongated hole-type bore  14 - 2  also holds analogously for a circular bore  14 - 1  and for a corresponding depression  24 - 1  ( FIG. 1 ). In the case of a circular bore  14 - 1 , the ratio of width W to height H of bore  14 - 1  is one. It should also be appreciated that the ratios described for elongated hole  14 - 2  of width W to height H are exemplary for the orientation shown here of elongated hole  14 - 2 . Also conceivable is an elongated hole that is rotated by 90°, so that height H has a larger value than width W. In such a case, ratio W/H would assume a value of less than one. 
       FIG. 4  shows a sectional view of a connection assembly  40  having a liner element  10 . The connection assembly includes a connection unit  42 . In this example, connection unit  42  includes a threaded bolt  44  and a nut  46  bolted thereon. Threaded bolt  44  is also connected to a component  48 , in particular received in a bore  50  thereof. Threaded bolt  44  is also conceivably joined in a material-to-material bond to component  48 , for example welded thereto. 
     By bore  14 - 1  or  14 - 2  thereof, liner element  10  is placed over threaded bolt  44 . In other words, threaded bolt  44  is inserted into the bore along bore axis BA of bore  14 - 1 ,  14 - 2 . Depression  24 - 1 ,  24 - 2  of the bore is accommodated between two washers  52 ,  54 , the one washer  52  resting against nut  46 , and the other washer  54  against component  48 . Fastening portion  12  rests by side  34  of rim portion  26  against washer  54 . To ensure that the depression is not flattened by pressure when the connection is made between liner element  10  and component  48 , a spacer sleeve  56  is accommodated in bore  14 - 1 ,  14 - 2 . Spacer sleeve  56  thereby has an axial thickness AT which, in the assembled state, essentially corresponds to an axial distance from surface  28  of fastening portion  12  to side  34  of rim portion  26  ( FIG. 3B ). In this context, axial thickness AT of the spacer sleeve may preferably be smaller than depth DD of the depression plus material thickness MT ( FIG. 3B ). A fastening of liner element  10  in a prestressed state in the area of bores  14 - 1 ,  14 - 2  is hereby possible due to the resilient effect of depressions  24 - 1 ,  24 - 2 . Close fits or sliding fits may be provided, depending on the embodiment of bores  14 - 1 ,  14 - 2 , so that, in addition to the secure fastening by connection unit  42 , it is possible to determine whether a shifting of liner element  10  and component  48  relative to each other is to be made possible along an elongated bore  14 - 2 . 
     Configuring depression  24 - 1 ,  24 - 2  in the area of bores  14 - 1 ,  14 - 2  eliminates the need for small-size parts, such as disk springs. By integrating depression  24 - 1 ,  24 - 2  in liner element  10 , a resilient or compensating element is formed for connection assembly  40 . Connection assembly  40  presented here damps vibrations and compensates for thermal expansions. 
     Liner element  10  may be a protective heat shield, for example, or some other casing element. Further component  48  illustrated in  FIG. 4  may be a casing part, a type of frame or strut section or the like of the gas turbine. Besides the described bolt-and-nut connection, the connection unit may also be in the form of a rivet. 
     LIST OF REFERENCE NUMERALS 
       10  liner element 
       12  fastening portion 
       13  rim 
       14 - 1  circular bore 
       14 - 2  elongated bore 
       16  liner portion 
       18  radially inner portion 
       20  radially outer portion 
       22  intermediate portion 
       24 - 1  circular depression 
       24 - 2  elongated hole-type depression 
       26  rim portion 
       28  surface 
       30  first curvature 
       32  second curvature 
       34  side of the rim portion 
       40  connection assembly 
       42  connection unit 
       44  threaded bolt 
       46  nut 
       48  further component 
       50  bore 
       52  washer 
       54  washer 
       56  spacer sleeve