Abstract:
An arrangement for supporting a brace transversely to the longitudinal extent thereof in the vicinity of the anchorage of a structure having a cavity pipe, an adapter ring, a tubular or annular supporting element which has a second axially loadable support surface, which is arranged concentrically in relation to the second axially loadable bearing surface of the adapter ring and of which the opening, which encircles a third longitudinal axis, forms a supporting surface for the brace by way of its inner circumference, wherein the opening has an amount of eccentricity E 2  in relation to the second axially loadable support surface of the supporting element, and having a fastenor which clamps the cavity pipe, the adapter ring and the supporting element together axially in position relative to one another.

Description:
[0001]    This nonprovisional application is a continuation of International Application No. PCT/EP2012/002612, which was filed on Jun. 21, 2012, and which claims priority to German Patent Application No. DE 10 2011 106 431.5, which was filed in Germany on Jul. 4, 2011, and which are both herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to an arrangement for supporting a tension member, in particular a stay cable or a prestressing member, transversely with respect to the longitudinal extent thereof in a vicinity of the anchorage of a. 
         [0004]    2. Description of the Background Art 
         [0005]    Tension members of this type are known primarily as stay cables or external prestressing members of bridge structures, where they have a key function in the accommodation and transfer of loads that are present. For this purpose the tension members, composed of steel rods, steel wires, or steel strands, are tensioned between two components of a structure, the ends of each tension member being guided through the components within a channel and anchored at their rear side. The tension members extend freely in the free area between the anchorings. 
         [0006]    Due to dynamic loads such as wind loads or traffic loads, for example, as well as temperature-related deformations of the structure, movements of the tension member in the operating state, in particular also in the transverse direction, are unavoidable. While such movements in the free area are acceptable within limits, they adversely affect the fatigue strength of the tension member in the anchoring area. This is counteracted by intercepting the movements in the transverse direction. 
         [0007]    To this end, a tension member which extends in the anchoring area within a pretensioning channel which is formed by a cavity pipe is known from DE 295 04 739 U1. For concentrically fixing the tension member in the pretensioning channel, the tension member is enclosed by a ring tensioning element which on the one hand bundles the individual strands of the tension member before they are spread toward the anchoring, and on the other hand with its outer periphery contacts the inner side of the cavity pipe. In this way, movements of the tension member transverse to its longitudinal extent are limited to the area outside the pretensioning channel, thus increasing the fatigue strength of the tension member. 
         [0008]    Due to manufacturing- and installation-related tolerances or the slack in stay cables, it is often the case that the actual longitudinal axis of the tension member differs from the target axis. To take these tolerances into account, it is necessary to fix the tension member eccentrically, not concentrically, in the pretensioning channel. This problem is addressed in the invention described in DE 34 34 620 A1, which corresponds to U.S. Pat. No. 4,648,147, in which a sufficiently large annular chamber which expands the pretensioning channel within the structure via a longitudinal section provides space for the eccentric accommodation of the tension member. After the annular chamber is sealed off, it is pressed with a setting or loose, free-flowing material, thus fixing the eccentric position of the tension member within the pretensioning channel. In many cases this approach has proven satisfactory in practice. 
         [0009]    A similar procedure is disclosed in DE 295 17 250 U1, according to which an annular closed pad is arranged around the tension member, forming a closed cavity, so that without further sealing operations, pressing may be carried out using a setting material while at the same time fixing the tension member. 
         [0010]    To avoid the expenditure of time and effort associated with the pressing process, it is already known from DE 200 14 322 U1 to situate two circular rings, each having an eccentric opening, inside one another in such a way that they may be rotated relative to one another in the shared circumferential joint. The inner circular ring encloses the tension member, while the outer periphery of the outer circular ring is supported on the cavity pipe. The opening in the inner ring may be adapted to the eccentricity of the tension member by mutually rotating the rings. 
       SUMMARY OF THE INVENTION 
       [0011]    It is therefore an object of the invention to provide a support of a tension member in the vicinity of the anchorage, transversely with respect to the longitudinal extent of the tension member. 
         [0012]    The basic concept of the invention lies in providing an eccentric support of the tension member by the interaction of multiple mechanical components arranged axially in succession, wherein by providing bearing and support surfaces which extend eccentrically with respect to one another, partial eccentricities E 1  and E 2  result at the components which provide the given eccentricity in a predetermined position relative to one another by suitable overlapping in the course of assembling the individual components. The force-fit connection between the individual components is established via the axially loadable bearing and support surfaces, which are clamped together by means of axial clamping elements. 
         [0013]    A first advantage of the invention results from the design which develops in the axial direction, i.e., in a direction in which tension members have sufficient free space in the normal case. The arrangement according to the invention may be kept narrow in the radial direction, which is advantageous not only with regard to appearance, but also with regard to the limited space in the vicinity of the anchorage. 
         [0014]    Due to an axial connection of the arrangement according to the invention to the cavity pipe, the site of installation, in contrast to the known approaches, is outside the cavity pipe, and is therefore easily accessible from the outside. This simplifies not only assembly and disassembly of an arrangement according to the invention, but also its maintenance and repairs, if necessary. 
         [0015]    In the event that the eccentricity E of the tension member changes over time due to deformation characteristics of the structure, the arrangement according to the invention, due to its capability for disassembly, easily allows subsequent adaptation to the altered geometry. 
         [0016]    Another advantage of the invention is that constructional measures on the structure, for example providing an annular chamber in the cavity pipe, are not necessary. This is advantageous first of all from an economic standpoint, since a corresponding level of effort is not required. At the same time, however, the arrangement according to the invention opens the possibility for retrofitting or modifying existing structures without a great additional level of design effort for the structure itself. 
         [0017]    Since an arrangement according to the invention is produced merely by assembling a few mechanical components, the necessary outlay of materials and time is very small, which further increases the cost-effectiveness of the invention. 
         [0018]    In an embodiment of the invention, the two partial eccentricities E 1  and E 2  are equal, which results in the possibility of also adjusting the arrangement according to the invention to a tension member which extends centrally in the cavity pipe. For an eccentricity E that is present, which is larger than the sum of the two equal partial eccentricities E 1  and E 2 , it is also conceivable that, by using a specialized adapter ring or supporting element, one of the two partial eccentricities E 1  or E 2  may be larger than the other. 
         [0019]    One embodiment of the invention has also proven advantageous in which, in addition to the axially loadable bearing or support surfaces, radially loadable bearing surfaces are provided. The radially loadable bearing surfaces primarily take over the function of guiding and centering surfaces which simplify the axial joining of the individual components as well as their rotation about the longitudinal axis. 
         [0020]    The axially loadable bearing or support surfaces may be composed of multiple partial surfaces which are stepped in the axial direction. The axial offset of the partial surfaces may advantageously be utilized for forming the radially loadable bearing surfaces. It is thus possible for the axial pressure forces in the contact joint to be transferred via a relatively large assembled bearing or support surface, which contributes to the overall stability of the connection. 
         [0021]    According to an embodiment of the invention, the axially and/or radially loadable bearing or support surfaces may be equipped with anti-slip protection. This may be achieved by a suitable surface roughness or by coating with slip-resistant materials such as zinc silicate or the like. As the result of equipping with anti-slip protection, the force-fit connection between the individual components, and thus positional stability thereof, is enhanced. 
         [0022]    The components of an arrangement according to the invention are advantageously clamped together by means of a clamping ring and clamping bolts. As the result of a relative position of the clamping bolts radially outside the axially loadable bearing or support surfaces, a stepless setting of the partial eccentricities E 1  and E 2 , and thus a highly precise adaptation to a given eccentricity E, is ensured. 
         [0023]    To avoid bending stresses in the clamping ring and/or the clamping bolts, another advantageous embodiment of the invention has a spacer ring between the ring flange of the cavity pipe and the adapter ring. To simplify assembly, the spacer ring may be welded to the ring flange or adapter ring. 
         [0024]    In particular for subsequent installation of the arrangement according to the invention on a tension member, it has proven advantageous for the adapter ring and/or the supporting element and/or the clamping ring to have a two-part design. The two halves may thus be arranged around the tension member and held together without the tension member having to be removed for the assembly or disassembly. 
         [0025]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
           [0027]      FIG. 1  shows a partial view of a stayed-cable bridge having an arrangement according to the invention, 
           [0028]      FIG. 2  shows a longitudinal section of the area denoted by reference numeral II in  FIG. 1 , 
           [0029]      FIG. 3 ,  4  each show an oblique view of the area, denoted by reference numeral III in  FIG. 2 , of an arrangement according to the invention in an exploded illustration, 
           [0030]      FIG. 5  shows a longitudinal section of the arrangement illustrated in  FIGS. 3 and 4 , 
           [0031]      FIGS. 6   a - e  show views A-A through E-E as provided in  FIG. 5 , 
           [0032]      FIG. 7  shows a partial longitudinal section of the connecting area of the supporting element and the adapter ring, in larger scale, 
           [0033]      FIG. 8  shows a partial longitudinal section of one refinement of the arrangement according to the invention, 
           [0034]      FIGS. 9   a - d  show sections, each in a longitudinal section, and 
           [0035]      FIGS. 10   a - c  show examples of centric and eccentric support of a stay cable. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]      FIG. 1  shows a portion of a stayed-cable bridge  1  having a pylon  2  made of reinforced concrete, on which a bridge girder  3  is suspended by means of stay cables  4 . The anchoring areas for the stay cables  4  on the pylon  2  and the bridge girder  3  are formed by a pretensioning channel which is composed essentially of a steel cavity pipe  5  which is guided through the pylon  2  and the bridge girder  3  and which has been embedded in concrete in the course of production of the pretensioning channel. The pretensioning channel, i.e., the cavity pipe  5 , is used for accommodating a stay cable  4  in each case. 
         [0037]      FIG. 2  depicts the lower anchoring area denoted by reference numeral II in  FIG. 1 , in enlarged scale. A cavity pipe  5  is shown which extends coaxially along a first longitudinal axis  6  and which passes through the bridge girder  3  and ends at the underside of the bridge girder, flush with an abutment pedestal  7  present there. The cavity pipe  5  forms a projection at the top side of the bridge girder  3 . The anchoring area in the region of the pylon  2  has an essentially corresponding design, taking into account necessary modifications for adapting to the conditions at that location. 
         [0038]    The tension member  4 , which in the present example is formed by a bundle of individual elements  8 , such as steel wire strands, situated within a protective pipe  9  extends within the cavity pipe  5 . The annular gap between the protective pipe  9  and the individual elements  8  may be filled with a setting corrosion protection compound. The longitudinal axis of the tension member is denoted by reference numeral  12 . 
         [0039]    In the free area of the tension member  4  the individual elements  8  extend axially parallel at a close radial distance from one another. To provide sufficient space for the anchoring of the individual elements  8 , the individual elements  8  in the anchoring area are spread within the cavity pipe  5  in the direction of the anchoring. For accommodating the ring tension forces which arise in the transition area due to the spreading, the individual elements  8  are enclosed in a cuff-like manner by a ring tensioning element  10 , which in turn has an elastomeric bearing  11  on its outer periphery. 
         [0040]    The individual elements  8  are secured in an anchor block  13  by means of wedges, the anchor block engaging with a ring nut  14  via a male thread. The ring nut  14  is supported on a support plate  15 , which in turn lies against the abutment pedestal  7  and introduces the tensile forces from the tension member  4  into the structure  1 . A cap  16  which is tightly connected to the ring nut  14  and is filled with a corrosion protection compound encloses the free ends of the individual elements  8 . 
         [0041]    In the free area the tension member  4  is enclosed by HDPE piping  17  which ends at an axial distance in front of the cavity pipe  5 . 
         [0042]    Due to manufacturing- and installation-related tolerances as well as load-related deformations of the structure, in the anchoring area the longitudinal axis  6  of the cavity pipe  5  and the longitudinal axis  12  of the tension member  4  frequently do not coincide. As a result, the tension member  4  does not adjoin the cavity pipe  5  centrally, and instead has an eccentricity E with respect to the longitudinal axis  6  at that location. 
         [0043]    To minimize the negative effects, described at the outset, of transverse movements of the tension member  4  in the immediate anchoring area to the greatest extent possible, in the area of the ring tensioning element  10  the tension member  4  is secured against movements transverse to its longitudinal axis  12  by means of a support. A tubular supporting element  18  which at one end adjoins a bushing-like enlargement  19  of the piping  17  and at its opposite end is rigidly connected to the cavity pipe  5  via the flange connection according to the invention is used for this purpose. It is thus possible for the tension member  4  together with the elastomeric bearings  11  to lie against the inner periphery of the supporting element  18  and thus be held in position. During its installation, the supporting element  18  is already adjusted to the existing eccentricity E of the longitudinal axis  12  with respect to the longitudinal axis  6 . The structural design necessary for this purpose is explained in greater detail below with reference to  FIGS. 3 through 7 . 
         [0044]      FIGS. 3 through 5  and  7  each show the arrangement according to the invention in an exploded illustration. The end of the cavity pipe  5  together with the individual components of the supporting element  18  according to the invention which is to be connected to the cavity pipe  5  are apparent. To this end, a ring flange  20  which encircles the outer periphery of the cavity pipe  5  forms the termination of the cavity pipe  5 . The ring flange  20  at its side facing the supporting element  18  and perpendicular to the longitudinal axis  6  forms a first axially loadable bearing surface  21  which is encircled by a number of axial through holes  22  which are situated on the same circumference and at equal circumferential distances.  FIG. 6 , view A-A shows an axial view of the ring flange  20 . 
         [0045]    An adapter ring  23  which adjoins in the axial direction and which encloses a central opening  30  cooperates with the ring flange  20 . The first side of the adapter ring  23 , facing the ring flange  20 , is illustrated in  FIG. 6 , view B-B, and the opposite second side is illustrated in view C-C.  FIGS. 3 through 6  and in particular  FIG. 7  clearly show that along the outer periphery, the first side of the adapter ring  23  has an edge recess  24  which concentrically encircles the longitudinal axis  6  and results in a shoulder. A first stepped axially loadable support surface  25 ′ and a radially loadable support surface  25 ″ ( FIG. 7 ) are formed in this way. During assembly of the arrangement according to the invention, the adapter ring  23  at the support surface  25 ″ may be inserted in a positive-fit manner into the end of the cavity pipe  5  until the support surface  25 ′ lies against the ring flange  20  of the cavity pipe  5 . At this point in the assembly, the adapter ring  23  may still be arbitrarily rotated about the longitudinal axis  6  for setting a predefined first partial eccentricity E 1 . 
         [0046]    The specific configuration of the second side of the adapter ring  23  is apparent from  FIGS. 3 through 6  and in particular  FIG. 7 . At this location a step-shaped edge recess  29  which encircles concentrically with respect to a second axis  28  is present along the inner periphery of the opening  30 , the axis  28  of the edge recess extending axially parallel to the axis  6  with a first partial eccentricity E 1 . As a result of the edge recess  29 , a second stepped axially loadable bearing surface  27 ′ and a second radially loadable support surface  27 ″ are formed ( FIG. 7 ). The two edge recesses  24  and  29  each have a rectangular cross section, the radial cross-sectional dimensions of the edge recess  29  constantly changing due to the partial eccentricity E 1 . The radially loadable bearing surface  25 ″ and support surface  27 ″ may also have a slightly conical shape in order to simplify the axial connection of the adapter ring  23  to the cavity pipe  5 , and of the supporting element  18  to the adapter ring  23 . 
         [0047]    The edge recess  29  in the adapter ring  23  is used for the axial connection of a tubular supporting element  18  which is composed of a tubular section  31  whose inner periphery is intended for supporting the tension member  4 , and an eccentric flange  32  which is fixedly connected to the end of the tubular section  31  facing the adapter ring  23 . In the process, the longitudinal axis of the tubular section  31  coincides with the axis  12  of the tension member  4 . 
         [0048]    The eccentric flange  32  has a circumferential outer edge recess  26  along its outer periphery which, similarly as for the adapter ring  23 , forms a second axially loadable support surface  33 ′ and a radially loadable support surface  33 ″. The edge recess  26  extends concentrically with respect to the edge recess  29  in the adapter ring  23 , and eccentrically with respect to the opening in the tubular section  31  and with respect to the axis  12 , resulting in a second partial eccentricity E 2 . 
         [0049]    The second axially loadable support surface  33 ′ of the eccentric flange  32  has a design that is complementary to the second axially loadable bearing surface  27 ′ of the adapter ring  23 . The direction of the partial eccentricity E 2  may be set by rotating the supporting element  30  relative to the adapter ring  23  about the axis  28  during assembly of an arrangement according to the invention. 
         [0050]    A clamping ring  34  is used for fixing the adapter ring  23  and the supporting element  18  in a predetermined position relative to the cavity pipe  5 . The clamping ring  34  has an opening  35  whose diameter is smaller than the outer periphery of the eccentric flange  32 , thus ensuring axial contact of the clamping ring  34  on the eccentric flange  32  in any position. The opening  35  may extend centrically as well as eccentrically with respect to the outer periphery of the clamping ring  34 . 
         [0051]    Axial through holes  36  are situated in the clamping ring  34 , and have a hole pattern that corresponds to that of the ring flange  20 , so that the clamping ring  34  may be clamped against the ring flange  20  by means of the axial clamping bolts  37  and associated nuts  38 , with clamping of the adapter ring  23  and eccentric flange  32  ( FIGS. 5 and 8 ). 
         [0052]    The installation of an arrangement according to the invention is explained in greater detail below, with consideration of a possible deviation of the longitudinal axis  12  of a tension member  4  from the longitudinal axis  6  of the anchoring. 
         [0053]    After the tension member  4  is installed, the eccentricity E of the tension member  4  with respect to the longitudinal axis  6  of the cavity pipe  5  is measured. Based on the eccentricity E that is present, the relative target position of the adapter ring  23  with respect to the cavity pipe  5  and the relative target position of the supporting element  18  with respect to the adapter ring  23  may be determined. A single degree of freedom for achieving the target position is the individual rotation of the adapter ring  23  and of the supporting element  18  about their longitudinal axes, so that in each case the radial direction of the partial eccentricities E 1  and E 2  may be set. Vector addition of the partial eccentricities E 1  and E 2  results in the magnitude and the direction of the overall eccentricity E. With regard to the eccentricity E that is present, and taking into account the previously determined directions of the partial eccentricities E 1  and E 2  of the tension member  4  in the axial direction, the adapter ring  23  and the supporting element  18  are thus placed on the end of the cavity pipe  5 , and by means of the clamping ring  34 , the clamping bolt  37 , and nuts  38  are clamped against the ring flange  20  and thus fixed in the required position relative to one another. This state is shown in a sectional view in  FIG. 8 . 
         [0054]      FIGS. 10   a  through  10   c  show examples of three possible cases of the eccentricity E which may occur during installation of a tension member  4 .  FIG. 10   a  shows the central position of the tension member  4  within the cavity pipe  5 ,  FIG. 10   b  shows a relative position of the tension member  4  with respect to the cavity pipe  5  in which the maximum compensable eccentricity E is achieved, and  FIG. 10   c  shows the most frequently occurring normal case in which the eccentricity E of the tension member  4  is less than the maximum compensable eccentricity E. Point  39  denotes the longitudinal axis  6  of the cavity pipe  5 , point  39 ′ denotes the position of the axis  28  due to the partial eccentricity E 1  after setting the adapter ring  23 , and point  39 ″ denotes the position of the longitudinal axis  12  of the tension member  4  after setting the eccentricity E 2  by rotating the supporting element  18  and overlapping the two eccentricities E 1  and E 2 . 
         [0055]    In the case of the central course of the longitudinal axis  12  of the tension member within the cavity pipe  5  ( FIG. 10   a ), the adapter ring  23  and the supporting element  18  are joined together in such a way that the partial eccentricities E 1  and E 2  act in opposite directions. If the partial eccentricities E 1  and E 2  are equal, they cancel each other out, and the magnitude of the overall eccentricity E is zero. 
         [0056]    The maximum overall eccentricity E ( FIG. 10   b ) is achieved when the partial eccentricity E 1  of the adapter ring  23  and the partial eccentricity E 2  of the supporting element  18  point in the same direction, and are thus additive. 
         [0057]    The areas between a central position of the longitudinal axis  12  of the tension member in the cavity pipe  5  and a maximum compensable eccentric position of the longitudinal axis  12  of the tension member are denoted by the circular line  48 , and may be covered by a suitable overlapping of the two partial eccentricities E 1  and E 2 , as illustrated in  FIG. 10   c , for example. In  FIG. 10   c , the direction of the partial eccentricity E 1  is initially set by appropriately rotating the adapter ring  23  about its longitudinal axis, obliquely and downwardly to the right (135° from the vertical). In the course of attaching the supporting element  18 , whose partial eccentricity E 2  points to the left (270° from the vertical), the direction and the magnitude of the desired overall eccentricity E result. 
         [0058]      FIGS. 8 and 9  show modifications of the invention described with respect to  FIGS. 1 through 7 .  FIG. 8  shows a partial longitudinal section of the connecting area of the adapter ring  23  and the supporting element  30  on the cavity pipe  5 . This embodiment essentially corresponds to that described in  FIGS. 1 through 7 , so that the description for these figures applies and the same reference numerals are used. 
         [0059]    In addition, the embodiment illustrated in  FIG. 8  has a support ring  40  which bridges the axial distance between the ring flange  20  and the clamping ring  34 . The support ring  40  extends over the entire periphery, radially outside the through holes  22  and  36 , and is preferably welded to the ring flange  20  or to the clamping ring  34 . 
         [0060]    Further embodiments of the invention are explained with respect to  FIGS. 9   a  through  9   d;    FIG. 9   a  relates to a simplified embodiment. The cavity pipe  5  together with the ring flange  20  illustrated in  FIG. 9   a  corresponds to that described with reference to  FIGS. 1 through 8 . The adapter ring  23 ′ is formed by a planar annular disc whose outer periphery extends concentrically with respect to the inner periphery. A first hole circle having a series of threaded holes whose hole pattern corresponds to the hole pattern of the through holes  22  in the ring flange  20  is likewise provided concentrically with respect to the outer periphery. A second hole circle having a smaller diameter extends eccentrically with respect to the first hole circle and concentrically with respect to the inner periphery of the adapter ring  23 ′, and has a hole pattern that corresponds to the hole pattern of the through holes  36  in the clamping ring  34 . By means of the screws  42  associated with the first hole circle, the adapter ring  23 ′ is screwed to the ring flange  20  in such a way that the partial eccentricity E 1  points in the predetermined direction. The setting of the eccentricity E 1  by rotating the adapter ring  23 ′ is possible only in a stepped manner in the peripheral spacing of the through holes  22 . 
         [0061]    By means of the screws  44  associated with the second hole circle, the threaded holes of the second hole circle are used to connect the supporting element  18 , which with its eccentric flange  32 ′ is screwed to the adapter ring  23 ′ from the opposite side via the through holes  45 . Here as well, setting of the partial eccentricity E 2  by rotating about the longitudinal axis is possible only in a stepped manner in the grid of the peripheral spacing of the threaded holes of the second hole circle. 
         [0062]      FIG. 9   b  shows a first refinement of the embodiment illustrated in  FIG. 9   a , in which the supporting element  18  is adjustable to the partial eccentricity E 2  in a stepless manner. The cavity pipe  5  and the connection of the adapter ring  23 ″ to the cavity pipe  5  correspond to that described with reference to  FIG. 9   a.    
         [0063]    The embodiment according to  FIG. 9   b  differs from that described in  FIG. 9   a  in that the second hole circle in the adapter ring  23 ″ has a larger diameter than the outer periphery of the eccentric flange  32  which is to be axially connected. The screws  44  thus lie radially outside the eccentric flange  32 , and via the clamping ring  34  exert a clamping force only in the outermost edge area of the eccentric flange  32 . The screws  44  do not hinder the rotation of the supporting element  18  about its longitudinal axis, so that it is possible to rotate the supporting element relative to the adapter ring  23 ″ in a stepless manner. 
         [0064]    To optimally prevent bending stresses in the screws  44  and in the clamping ring  34 , a spacer ring  46  through which the screws  44  pass is situated between the adapter ring  23 ″ and the clamping ring  34 . The spacer ring  46  may be loosely inserted between the adapter ring  23 ″ and the clamping ring  34 , or may be integrally molded to the adapter ring  23 ″ or clamping ring  34  as a ring shoulder. 
         [0065]    The embodiment according to the invention according to  FIG. 9   c  allows the partial eccentricity E 1  to be set in a stepless manner. To this end, the outer periphery of the adapter ring  23 ″′ protrudes radially beyond the outer periphery of the ring flange  20 ′. A clamping flange  47  is clamped against the adapter ring  23 ″′ by means of the screws  42 , and engages behind the ring flange  20 ′. Here as well, a spacer ring  43  through which the screws  42  pass may be situated between the adapter ring  23 ″′ and the clamping flange  47 , the spacer ring being loosely inserted between the two parts, or integrally molded to the clamping flange  47  or the adapter ring  23 ″′ as a ring shoulder. The rest of the structural design of the connection of the supporting element  18  to the adapter ring  23 ″′ corresponds to that described with reference to  FIG. 9   a.    
         [0066]    The embodiment shown in  FIG. 9   d  corresponds to a combination of the embodiments illustrated in  FIGS. 9   b  and  9   c , which due to a clamping fastening of the adapter ring  23 ″ to the ring flange  20 ′ of the cavity pipe  5  and to the eccentric flange  32  of the supporting element  18  allows the partial eccentricity E 1  as well as the partial eccentricity E 2  to be set in a stepless manner. 
         [0067]    It is understood that the invention is not limited to the feature combinations of the individual exemplary embodiments, and also includes combinations of the features of different embodiments. 
         [0068]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.