Abstract:
The invention relates to a pressure measuring arrangement comprising a pressure measuring cell which is fed by a pressure corresponding to the pressure which is to be measured by a pressure tube filled by a pressurised liquid; at least one pressure recording unit is arranged separately from said cell, said unit being impinged upon by a pressure which is to be measured during operation, producing a pressure corresponding to the pressure which is to be measured via a pressure line filled by a liquid; a connection between the pressure tube and the pressure line. A modular design and a large amount of flexibility is obtained in respect of the spatial arrangement of the pressure measuring cell and the pressure recording unit. The connection consists of a base body wherein at least one end section of the pressure line is arranged, in addition to a pressure screw through which the pressure tube passes and is secured by a fixing element arranged on a side which is oriented towards the base body of the pressure screw. Said pressure screw has a thread which enables it to be screwed onto base body in such a way that the pressure tube and the pressure line are connected, and the connection is effectively sealed between the pressure tube and the pressure line.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a pressure measuring arrangement with a pressure measuring cell and a pressure recording unit, in which in operation a pressure to be measured acts on the pressure recording unit and is converted into a pressure corresponding to the pressure to be measured, which converted pressure is delivered via a fluid-filled connection from the pressure recorder to the pressure measuring cell of the pressure measuring cell. 
   BACKGROUND OF THE INVENTION 
   Such pressure measuring arrangements are used if a pressure to be measured cannot be delivered directly to the pressure measuring cell. This is the case for instance whenever the pressure measuring cell is very vulnerable to chemical and/or mechanical stresses, as is the case for instance with piezoresistive pressure measuring cells that for instance have measuring membranes comprising or having vulnerable semiconductor components, or if a difference between two pressures that act at different locations is to be detected with a measuring cell embodied as a differential-pressure measuring cell. Such pressure measuring arrangements are also used if a ceramic pressure measuring cell is to be used and if, for instance for hygienic reasons, a flush closure off from the process at the front is desired. These pressure measuring arrangements must be filled, once their manufacture is concluded, with a fluid that transmits the pressure corresponding to the pressure to be measured. To that end, the measuring arrangement is evacuated, for instance, and placed in a bath with the fluid and flooded. The fill openings are then closed, and the measuring arrangement can be connected to a site where it will be used. 
   Since the filling is comparatively complicated and requires special operating media, a measuring arrangement once completed is as a rule no longer changed. 
   For the sake of great flexibility with a view to measuring arrangements that can be furnished quickly, examples being various possible combinations of different pressure measuring cells with different pressure measurement recorders, or different oil supplies or pressure lines of different lengths, without having to keep all possible variants of pressure measuring arrangements on hand in adequate numbers, it is therefore desirable for such a pressure measuring arrangement to be embodied in modular fashion and then put together and filled as needed. 
   U.S Pat. No. 4,833,922 describes a differential-pressure measuring cell of modular construction, having: a pressure measuring cell, to which a pressure corresponding to a pressure to be measured is delivered via a fluid-filled pressure tube; at least one pressure recording unit, on which in operation a pressure to be measured acts, and which makes a pressure corresponding to the pressure to be measured available via a fluid-filled pressure line; and a connection between the pressure tube and the pressure line. 
   The differential-pressure measuring cell is very compactly designed. To that end, the pressure measuring cell is disposed directly in the pressure recording unit, and the pressure tubes are introduced into bores of the pressure recorder that form pressure lines. Frustoconical sealing elements are provided, which annularly surround the pressure tubes and are introduced into recesses of the same shape in the pressure recorder. A fastening is provided that presses the sealing elements inward into the recesses of the same shape. The fastening surrounds the pressure tubes annularly and is screwed onto the pressure recorded, for instance by means of tension bolts. 
   Such a compact design is not always usable. For instance, space conditions at the usage site, high temperatures acting on the pressure recorder, or pressure measuring cells that require a special mode of installation, for instance in a manner that is as free from fastening as possible, necessitate a spatial separation of the pressure measuring cell and the pressure recorder. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a pressure measuring arrangement which is of modular construction and has a high degree of flexibility in terms of the three-dimensional disposition of the pressure measuring cell and the pressure recorder relative to one another. 
   To this end, the present invention comprises a pressure measuring arrangement, having:
         a pressure measuring cell; to which a pressure corresponding to a pressure to be measured is delivered via a fluid-filled pressure tube;   at least one pressure recording unit disposed separately therefrom, on which in operation a pressure to be measured acts, and which makes a pressure corresponding to the pressure to be measured available via a fluid-filled pressure line; and   a connection between the pressure tube and the pressure line, which connection includes:   a base body, in which at least one end portion of the pressure line is disposed,   a pressure screw, through which screw the pressure tube is passed and is secured there by means of a mount disposed on a side of the pressure screw oriented toward the base body, and which screw has a thread by means of which it is screwed onto the base body, in such a way that the pressure tube and the pressure line communicate, and sealing of die connection between the pressure tube and the pressure line is effective.       

   The present invention also comprises a pressure measuring arrangement, having:
         a pressure measuring cell; to which a pressure corresponding to a pressure to be measured is delivered via a fluid-filled pressure tube;   at least one pressure recording unit disposed separately therefrom, on which in operation a pressure to be measured acts, and which makes a pressure corresponding to the pressure to be measured available via a fluid-filled pressure line; and   a connection between the pressure tube and the pressure line, which connection includes:   a base body, in which at least one end portion of the pressure line is disposed;   a pressure screw, through which screw the pressure line is passed and is secured there by means of a mount disposed on a side of the pressure screw oriented toward the base body, and which screw has a thread by means of which it is screwed onto the base body, in such a way that the pressure tube and the pressure line communicate, and sealing of the connection between the pressure tube and the pressure line is effective.       

   In a first embodiment, the thread is a male thread, which is screwed into a recess in the base body. The pressure line or the pressure tube leads to the recess, and the mount is a ring mechanically solidly connected to the pressure tube or to the pressure line, which in the mounted state rests sealingly, with an end face oriented toward the pressure screw, on an end face of the pressure screw oriented toward the base body. 
   In a further feature, the pressure tube tapers conically on the outward end, and rests sealingly on a conical inside face of the same shape in the region of the orifice of the pressure line. 
   In a second embodiment, the pressure screw is a union nut, which takes the form of a cylinder closed on one end by a radially inward-extending shoulder. The cylinder has a female thread, which is screwed onto a male thread of the base body; and the pressure tube is passed through the shoulder into the pressure screw. 
   In a first feature of the second embodiment, the pressure line discharges into the base body and is connected tightly and mechanically solidly to it; the pressure tube is connected tightly and mechanically solidly to an annular disk coaxially surrounding the pressure tube; an end face of the annular disk rests on an annular-disklike inside face of the shoulder; and the annular disk is pressed by the pressure screw in the direction toward the base body. 
   In a feature of this last embodiment, between the annular disk and the base body, a sealing element annularly surrounding the pressure tube is provided, by which a hollow chamber, defined by the annular disk, the sealing element, and the base body, and surrounding the pressure tube is sealed off. 
   In a second feature of the second embodiment, the pressure tube is widened by crimping in the interior of the is pressure screw; the pressure line is introduced into the pressure tube; the pressure line is passed through the base body and mechanically solidly connected to it; the pressure line tapers conically on the outward end; and a crimped-on end portion of the pressure tube is fastened sealingly between a conical jacket face, disposed in the interior of the pressure screw, and the conical portion of the pressure line, in that the jacket face is pressed against the pressure line by the pressure screw in the direction toward the base body. 
   In a third feature of the second embodiment, a clamping cone is disposed on the end in the pressure screw, which clamping cone has an outer jacket face that tapers conically in the direction toward the base body, which jacket face grips the pressure tube and in which the pressure tube is fastened, in that the clamping cone is pressed inward with its conical jacket face by the pressure screw into an inner jacket face of the base body that is oriented toward the clamping cone and tapers conically in the direction remote from the clamping cone. 
   In a further feature of this last embodiment, on an end of the base body opposite the pressure screw, a second pressure screw of identical form is provided, through the pressure line is introduced into a bore penetrating the base body, in which bore a second clamping cone is disposed on the end, which clamping cone has an outer jacket face tapering conically in the direction toward the base body, which jacket face grips the pressure line and in which the pressure line is fastened, in that the second clamping cone is pressed inward with its conical jacket face by the second pressure screw into an inner jacket face of the base body oriented toward the second clamping cone and tapering conically in the direction remote from the clamping cone. 
   The present invention and further advantages will now be described in further detail in conjunction with the drawings, in which seven exemplary embodiments are shown. Identical elements are identified in the drawings by the same reference numerals. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a section through a pressure measuring arrangement of the invention, in which a pressure measuring cell is disposed in a housing disposed separately from a pressure recorder, and a pressure tube on the pressure recorder communicates with a pressure line of the pressure recorder; 
       FIG. 2  shows a section through a pressure measuring arrangement of the invention, in which a pressure measuring cell is disposed in a housing disposed separately from a pressure recorder, and a pressure line on the housing communicates with a pressure tube of the pressure measuring arrangement; 
       FIG. 3  shows a section through a connection according to the invention between a pressure tube and a pressure line, which is spaced apart from the pressure recorder and from the pressure measuring cell; 
       FIG. 4  shows a section through a further connection according to the invention between a pressure tube and a pressure line, which is spaced apart from the pressure recorder and from the pressure measuring cell; 
       FIG. 5  shows a section through a further exemplary embodiment of a connection according to the invention between a pressure tube and a pressure line, in which a portion of the pressure tube crimped on at the end is used to fix the pressure tube, and sealing is effected by means of conically embodied jacket faces of the pressure tube and pressure line; 
       FIG. 6  shows a section through a clamping cone connection between a pressure line and a pressure tube; and 
       FIG. 7  shows a section through a connection between a pressure line and a pressure tube, in which the pressure line and the pressure tube are each connected to a base body by means of a respective clamping cone connection. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a section through a pressure measuring arrangement of the invention. It has a capacitive ceramic pressure measuring cell, in this case a relative-pressure measuring cell, that is soldered onto a pressure tube  3  in a manner free from fastening in a housing  1 . 
   The pressure measuring cell  5  includes two ceramic base bodies  7 , between which a membrane  9  is disposed. The membrane  9  is connected by means of two annular joining points  11  to the base bodies  7 , forming a first and a second chamber  13 ,  15 . The first chamber  13  communicates with the pressure tube  3  via a bore in the base body  7 . In the exemplary embodiment shown, the pressure tube  3  is soldered into the bore in the base body  7 . By way of the pressure tube  3 , the pressure measuring cell  5  is supplied with a pressure corresponding to a pressure to be measured. 
   To that end, the first chamber  13  and the pressure tube  3  are filled with a substantially incompressible fluid, such as a silicone oil, that is acted upon by that pressure. 
   The second chamber  15  is opened relative to an interior of the housing  1  of the pressure measuring cell  5  via a bore  17  that passes continuously through the base body adjoining this second chamber. A deflection of the membrane  9  is thus dependent on the pressure corresponding to the pressure to be measured, which is referred to the ambient pressure operative in the interior of the housing. The deflection of the membrane is detected by a capacitor, which is disposed in the first chamber  13  and which has both a measuring electrode  19 , disposed on a bottom face of the base body  7  toward the membrane, and a counter-electrode  21  applied to the membrane  9  facing the measuring electrode. The measuring electrode  19 , for detecting the instantaneous capacitance, is connected via a through-connection through the base body  7  to an electronic circuit  23 , which converts the capacitance into an electrical output signal and makes it available for further processing and/or evaluation via connecting lines. 
   At least one pressure recording unit  25  is disposed separately from the housing  1  and from the pressure measuring cell  5 . In the exemplary embodiment shown, only one pressure recording unit  25  is provided. If instead of the relative-pressure measuring cell shown a differential-pressure measuring cell were provided, then it would be understood that there would be two pressure recording units, each connected to one pressure tube via a respective pressure line. A differential-pressure measuring cell of this kind could for instance be constructed similarly to the ceramic relative-pressure measuring cell described. From the relative-pressure measuring cell described, a differential-pressure measuring cell is obtained by introducing a second pressure tube into the open bore, shown in  FIG. 1 , of the second chamber  15 , which second pressure tube is connected to a second pressure line of a second pressure recorder. The pressure transmission from the second pressure recorder into the associated chamber is effected via a fluid, with which the pressure recorder, the second pressure line, the second pressure tube, and the chamber are filled. 
   The pressure recording unit  25  shown in  FIG. 1  has a base body  27  and a partitioning membrane  31 , secured on the front, enclosing a chamber  29 , to it by its outer edge. In operation, the pressure to be measured acts on the partitioning membrane  31  of the pressure recording unit  25 . The base body  27  and the partitioning membrane  31  comprise a metal, such as a special steel. 
   The base body  27  has a continuous bore, one end of which discharges into the chamber  29 . The bore forms a pressure line  33  and, just like the chamber  29 , is filled with a substantially incompressible fluid, such as a silicone oil. A pressure to be measured, which in operation is exerted on the outside of the partitioning membrane  31 , is converted in the chamber  29  into a pressure corresponding to it; the fluid is at this latter pressure and that pressure is available via the fluid-filled pressure line  33 . 
   A connection is provided between the pressure tube  3  and the pressure line  33 . The connection includes the base body  27 , in which at least an end portion of the pressure line  33  is disposed. In the exemplary embodiment shown, the entire pressure line  33  is disposed in the base body  27 . 
   The connection further includes a pressure screw  35 , through which the pressure tube  3  is passed. On a side of the pressure screw  35  toward the base body, a mount  39  is provided, by which the pressure tube  3  is secured. In the exemplary embodiment shown, the mount  39  is a ring, which is mechanically solidly connected to the pressure tube  3  and which in the mounted state rests, with an end face toward the pressure screw  35 , on an end face of the pressure screw  35  oriented toward the base body. In the exemplary embodiment shown, the mechanical fastening is realized by a male thread, formed onto the pressure tube  3 , onto which the mount  39  is screwed. The position of the male thread determines how far the pressure tube  3  protrudes out of the pressure screw  35  and out of the mount  39 . It is understood that still other mechanically solid connections that prevent a motion of the pressure tube  3  in the direction remote from the base body can also be used. For instance, the pressure tube  3  can be soldered into the mount  39  or welded there. 
   The pressure screw  35  has a thread  37 , by means of which it is screwed into the base body  27  in such a way that the pressure tube  3  and the pressure line  33  are in communication, and sealing between the pressure tube  3  and the pressure line  33  is effective. 
   In the exemplary embodiment shown in  FIG. 1 , the thread  37  is a male thread, which is screwed into a cylindrical recess  41  in the base body  27 . If the pressure screw  35  has a clockwise thread, then the mount  39  is preferable secured with a counterclockwise thread, to preclude loosening of the mount  39  when the pressure screw  35  is being screwed in. 
   The pressure tube  3  comprises a metal, such as a special steel. The mount  39  preferably likewise comprises a metal. The pressure line  33  leads to the recess  41  and discharges there. The pressure tube  3  tapers conically on the outward end and rests sealingly on a conical inside face  43 , of the same shape, of the base body  27  in the region of the orifice of the pressure line  33 . The mount  39  is thus located in the interior of the recess  41 , and the pressure tube  3  is pressed against the orifice of the pressure line  33  as a result of the screwing in of the pressure screw  35  and the resultant force exerted on the mount  39  in the direction toward the base body, so that the sealing of the connection between the pressure tube  3  and the pressure line  33  by the conical jacket faces pressed against one another is effective. 
     FIG. 2  shows an exemplary embodiment that substantially agrees with the exemplary embodiment shown in FIG.  1 . Unlike the exemplary embodiment shown in  FIG. 1 , however, the connection is not made directly at the pressure recorder  45  but instead near the pressure measuring cell  5 . For that purpose, the housing  1  in the region of the exit point of the pressure line  4  has a base body  28  formed onto it. The pressure tube  4  is soldered into a bore that penetrates the base body  28  and discharges there. Hence at least one end portion of the pressure tube  4  is disposed in the base body  28 . Analogously to the exemplary embodiment shown in  FIG. 1 , the base body  28  has a recess  41 , into which the pressure screw  35  is screwed. A pressure line  34  is provided, which leads from the pressure recorder  25  to the base body  28 , where it protrudes through the pressure screw  35  into the recess  41 . Just as in the exemplary embodiment shown in  FIG. 1 , an identically embodied mount  39  is provided here in the interior of the recess  41 , and this mount secures the pressure line  34 . 
   The sealing of the connection between the pressure line  34  and the pressure tube  4  is effected by providing the pressure line  34  with a conical outer jacket face on its end, which face is pressed into the recess  41  by the screwing in of the pressure screw  35  against an inner jacket face  44 , of the same shape, of the base body  28  in the region of the orifice of the bore. 
   The pressure recorder  45  has a base body  47  and a partitioning membrane  49  and is embodied similarly to the pressure recorder shown in FIG.  1 . The base body  47  has a continuous bore  51 , which discharges into a chamber  53  enclosed between the base body  47  and the partitioning membrane  49 . The pressure line  34  is welded or soldered into an end of the bore  51  remote from the chamber. 
     FIG. 3  shows a further exemplary embodiment, which is similar to both of the exemplary embodiments described above. A housing, not shown in  FIG. 3 , and a pressure measuring cell, also not shown, are, like the pressure line  3 , are embodied similarly to the corresponding components in  FIG. 1 , and the pressure recorder  45  corresponds to that shown in  FIG. 2. A  pressure line  55  is welded or soldered into the bore  51  of the pressure recorder  45 . 
   The pressure line  55  communicates with the pressure tube  3  that leads to the pressure measuring cell  5 , not shown in  FIG. 3. A  connection spaced apart from the pressure recorder  45  and from the pressure measuring cell  5  exists between the pressure tube  3  and the pressure line  55 , and it has a base body  57  in which an end portion of the pressure line  55  is disposed. The pressure line  55  and the base body  57  comprise a metal, such as a special steel. The base body  57  has a continuous bore, into which the pressure line  55  is for instance welded. 
   The connection of the pressure line  55  and the pressure tube  3  is effected analogously to the exemplary embodiment shown in  FIG. 1 , by means of a pressure screw  35 , screwed into the recess  41  in the base body  57 , and by means of a mount  39  and a conical jacket face of the pressure tube  3 , which face is pressed by the pressure screw  35  against an identically shaped conical jacket face of the base body  57  in the region of the orifice of the pressure line  55 , and so this connection is therefore not described again here. 
   In  FIGS. 4 and 5 , two further embodiments of connections, spaced apart from the pressure recorder and from the pressure measuring cell, between the pressure tube  3  and the pressure line  55  are shown. The pressure measuring cell  5  connected to the pressure tube  3  and the pressure recorder  25  connected to the pressure line  55  are not shown in  FIGS. 4 and 5 . Examples of them can be taken identically from  FIGS. 1 and 2 . 
   In the embodiments shown in  FIGS. 4 and 5 , the connection in each case includes a respective essentially cylindrical base body  59 ,  62 , with a central axial bore into which the pressure line  55  is introduced and is connected tightly and mechanically solidly by means of a soldered connection  63 . 
   In each case, a pressure screw  65  is provided that coaxially surrounds the pressure tube  3 . The pressure screws  65  are union nuts, which take the form of a cylinder closed at one end by a radially inward-extending shoulder  67 . The cylinders have a female thread, which is screwed onto a male thread of the base body  59 ,  62 . The pressure tubes  3  are passed through the shoulder  67  on into the union nut and secured by means of a mount disposed on a side, toward the base body, of the pressure screw  65 . 
   The union nuts are screwed onto the base bodies  59 ,  62  in such a way that the pressure tube  3  and the pressure line  55  are in communication, and sealing of the connection between the pressure tube  3  and the pressure line  55  is effective. In the exemplary embodiment shown in  FIG. 4 , the mount comprises an annular disk  69 , which coaxially surrounds the pressure tube  3  and is connected to it tightly and mechanically solidly, for instance by means of a soldered connection  71 . The annular disk  69  is disposed inside the pressure screw  65  and rests with one end face on an annular-disklike inside face of the shoulder  67 . The annular disk  69  is pressed against the base body  59  by the pressure screw  65 . 
   The pressure tube  3  is introduced through the mount into the base body  59 . The sealing of the connection is effected by a sealing element  73 , disposed between the annular disk  69  and the base body  59  and annularly surrounding the pressure tube  3 . By means of the sealing element  73 , a hollow chamber, which is defined by the annular disk  69 , sealing element  73  and base body  59 , and which encloses the connection between the pressure tube  3  and the pressure line  55 , is sealed off. The sealing element  73  in this exemplary embodiment is a ring of oval cross section, which rests on a conical end face of the base body  59 . Other seal geometries are equally usable. It comprises a metal, such as copper. The pressure screw  65  and the base body  59  likewise comprise a metal, such as a special steel. 
   In the exemplary embodiment shown in  FIG. 5 , the pressure tube  3  is widened by crimping in the interior of the pressure screw  65 . 
   The pressure line  55  is introduced through the base body  62  into the pressure tube  3  and is mechanically solidly connected to the base body by the soldered connection  63 . 
   The pressure line  55  tapers conically on its outer end. The mount, by which the pressure tube  3  is secured in the interior of the pressure screw  65 , essentially comprises the crimped-on portion  74  of the pressure tube  3  itself. This portion is fastened between a conical jacket face  75 ,  78 , disposed in the interior of the pressure screw  65 , and the conical portion of the pressure line  55 , in that the jacket face  75 ,  78  is pressed against the pressure line  55  in the direction toward the base body by the pressure screw  65 . By means of this fastening, the connection between the pressure tube  3  and the pressure line  55  is sealed off. 
   The jacket face  75 ,  78  is for instance, as shown on the right-hand side of  FIG. 5 , a conical jacket face  78  of the pressure screw  65  itself, or, as shown on the left-hand side of  FIG. 5 , a conical jacket face  75  of an annular cylinder  76  disposed in the pressure screw  65 . 
   In  FIGS. 6 and 7 , two further embodiments of the connection between the pressure tube  3  and the pressure line  55  are shown. The pressure measuring cell  5  connected to the pressure tube and the pressure recorder  25  connected to the pressure line  55  are not shown here, either. Examples of them can be taken identically from  FIGS. 1 and 2 , for instance. 
   In the embodiments shown in  FIGS. 6 and 7 , the connection in each case includes a substantially cylindrical base body  77 ,  79  with a central axial bore  81 ,  83  into which the pressure line  55  is introduced. 
   In each case a pressure screw  65  is provided, which coaxially surrounds the pressure tube  3  and is embodied identically the pressure screws  65  shown in  FIGS. 4 and 5 . The pressure screws  65  are union nuts, which take the form of a cylinder closed on one end by the radially inward-extending shoulder  67 . The cylinders have a female thread, which is screwed onto a male thread of the base body  77 ,  79 . The pressure tubes  3  are passed through the shoulder  67  into the pressure screw  65  and are secured by means of a mount disposed on a side, toward the base body, of the pressure screw  65 . 
   The pressure screws  65  are screwed onto the base bodies  77 ,  79  in such a way that the pressure tube  3  and the pressure line  55  communicate, and sealing of the connection between the pressure tube  3  and the pressure line  55  is effected. 
   In the exemplary embodiments shown in  FIGS. 6 and 7 , the sealing is effected by a clamping cone  85 , which is disposed on the end in the pressure screw  65  and at the same time forms the mount for the pressure tube  3  passed through the clamping cone  85 . 
   The clamping cone  85  grips the pressure tube  3  closely and rests with an annular-disklike end face on an inner face of the shoulder  67 . It has an outer jacket face  87  that tapers conically in the direction toward the base body. The base bodies  77 ,  79  each have a respective inner jacket face  89  tapering conically in the direction remote from the clamping cone. The pressure tube  3  is fastened in the clamping cone  85  in that the clamping cone  85  is pressed with its conical jacket face by the pressure screw  65  into the inner jacket face  89  of the respective base body  77 ,  79 , this latter jacket face tapering conically toward the clamping cone  85  in the direction remote from the clamping cone. 
   The conical outer jacket face  87  of the clamping cone  85  forms a more-acute angle with a longitudinal axis of the pressure tube  3  than does the inner jacket face  89  of the respective base body  77 ,  79 . As a result, some of the force exerted in the axial direction on the clamping cone  85  by the pressure screw  65  is converted into a force that acts inward in the radial direction. This latter force causes a decrease in the inside diameter of the clamping cone  85  and thus leads to the tight, mechanically solid fastening of the pressure tube  3  in the clamping cone  85 . 
   Once again, the base bodies  77 ,  79  and the pressure screws  65  comprise metal, such as a special steel. The clamping cone  85  preferably also comprises a metal. What is suitable is a material, such as copper, that is mechanically softer than the material comprising the base bodies  77 ,  79  and the pressure screws  65 . 
   In the exemplary embodiment shown in  FIG. 6 , the pressure line  55  is connected mechanically solidly and tightly to the base body  77 , for instance by being soldered into the bore  81 . 
   In the exemplary embodiment shown in  FIG. 7 , only one end of the pressure line  55  is introduced into the bore  83 , and the pressure line  55  is fastened in the same way as the pressure tube  3 . 
   To that end, an identically shaped second pressure screw  91  is provided, on an end of the base body  79  facing the pressure screw  67 , through which the pressure line  55  is introduced into the bore  83  that penetrates the base body  79 . The second pressure screw  91  is screwed onto the base body  79 . A second clamping cone  93  is disposed on the end in the second pressure screw  91  and has an outer jacket face  95  that tapers conically in the direction toward the base body. The second clamping cone  93  grips the pressure line  55 . This pressure line is fastened in the clamping cone  93 , in that the second pressure screw  91  presses the second clamping cone  93  with its conical jacket face  95  into an inner jacket face  97  of the base body  79  that tapers conically, toward the second clamping cone  93 , in the direction remote from the clamping cone. 
   It is understood that the exemplary embodiments shown in  FIGS. 3 ,  4 ,  5 ,  6  and  7  can also be embodied as a mirror image instead. The mirror-image form is obtained by simply converting the pressure tubes and pressure lines  55  and the pressure lines  55  into pressure tubes  3 .