Abstract:
A measuring device housing for a sensor component, which detects a physical parameter without contact is provided, having: a coupling apparatus for supplying at least one flushing medium and at least one signal transmission line in the housing interior, a guide pipe arranged on the coupling apparatus having a longitudinal axis and a probe head fastened on the end section of the guide pipe. The guide pipe is designed to conduct or accommodate the at least one cooling medium and the at least one signal transmission line up to the probe head. The probe head and the end section, relative to the longitudinal axis of the guide pipe or the probe head, each have radially extending passages for conducting the cooling media from the end section into the probe head and the reverse, as applicable.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2013/067030 filed Aug. 14, 2013, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102012216267.4 filed Sep. 13, 2012. All of the applications are incorporated by reference herein in their entirety. 
     FIELD OF INVENTION 
     The invention relates to a measuring device housing for a sensor component which detects a physical quantity contactlessly, or for such a sensor, comprising a coupling apparatus for feeding at least one coolant and/or flushing medium and at least one signal transmission line into the housing interior or into a housing wall, a guide tube arranged on the coupling apparatus and having a longitudinal axis, and a probe head fastened to an end section of the guide tube lying opposite the coupling apparatus, wherein the guide tube is configured in order to guide or accommodate at least one medium and the at least one signal transmission line as far as the probe head. 
     BACKGROUND OF INVENTION 
     A measuring device having such a housing is known, for example, from DE 10 2005 060 961 A1. The measuring device, also referred to as a measuring lance, principally comprises a tube in which the sensor lines and cooling air can be guided. The sensor lines and the coolant are introduced, or fed in, at one end of the tube. When the measuring lance is used in a gas turbine for radial gap detection, this end of the tube is arranged outside the housing of the gas turbine. The sensor is fastened on the other end of the tube. In order to protect the sensor from overheating, it is flanked by coaxial cooling air bores through which the cooling air flowing in the tube can emerge. 
     It is found disadvantageous that the sensor and its housing are relatively large and therefore have an increased cooling air requirement so that they can be used reliably. Another disadvantage is that the known measuring device is furthermore configured only for a single sensor. 
     SUMMARY OF INVENTION 
     An object of the invention is therefore to provide a measuring device housing for a sensor component which detects a physical quantity contactlessly, or for such a sensor, which on the one hand is relatively compact and in which the probe head can be replaced relatively easily. 
     This object of the invention is achieved with a measuring device housing according to the features of the independent claim. Advantageous configurations are specified in the dependent claims, which may be combined with one another in any desired way. 
     According to aspects of the invention, the probe head and the end section of the guide tube of the measuring device housing respectively comprise passages, extending radially relative to its longitudinal axis, for forwarding a coolant and/or flushing medium, or a plurality of coolants and/or flushing media, or the coolant from the end section into the probe head and optionally vice versa. 
     With the aid of the aforementioned configuration, it is possible to convey a coolant and/or flushing medium, or a plurality of such media, along the guide tube of a measuring device and to deliver it or them at the end section thereof into the probe head, and optionally convey it or them back therefrom. The delivery of the media takes place through passages, which are located both in the probe head and in the end section of the guide tube and which respectively extend radially. For each coolant, or for each delivery, the assigned passages must then be arranged in the same axial section. Since it is relatively difficult to align the passages in the probe head radially with the passages in the end section, an axially limited annular channel is left radially between the probe head and the guide tube, through which the coolant fed through the passages of the guide tube can subsequently be introduced through the radial passages of the probe head into the interior of the probe head. Of course, the same also applies for conveying back a medium which has already been used for its intended purpose. Advantageously, the passages are configured as radial bores in the guide tube and in the probe head, the outer openings of which have optionally been closed with plugs. 
     A particular advantage of the invention is that when the probe head is fastened releasably in the end section of the guide tube, which may be possible using a screw connection, different probe heads with differently arranged recesses can be releasably fastened on the guide tube, without the rest of the measuring device housing having to be replaced or provided in duplicate. This reduces the production costs of measuring devices, since for different viewing directions of optical probes it is then only necessary to provide different probe heads; the rest of the measuring device, or of the measuring device housing, can be used several times. 
     If a plurality of coolants and/or flushing media are guided in separate axial channels inside a guide tube, it is advantageous for a ring seal to be provided between the radial passages, which are distributed along the longitudinal axis, for axial delimitation of the annular channels. In this way, mixing of the separately guided different coolants can be avoided when delivering the coolant from the guide tube into the probe head, and optionally vice versa. 
     Advantageously, the probe head comprises a freely ending probe tip, and the end section of the guide tube and the probe head overlap axially in such a way that the radial passages are arranged axially between the fastening—for example the screw connection of the probe head and the end section—and the probe tip. 
     Also, a plurality of radial passages are provided in the circumferential direction of the probe head and/or the end section, so that a sufficiently large cross-sectional area can already be provided for the coolant in question. This reduces pressure losses during the guiding of the coolant in the measuring device housing. 
     In order to ensure an accurate fit of the probe head in the end section of the guide tube, guide elements may be provided either on the probe head or in the end section. 
     In order to separately guide different coolants relatively simply along the guide tube, along the end section and along the probe head, axially extending channels which extend on a radius lying coaxially with the midaxis of the guide tube, of the end section and of the probe head, respectively, are provided in these components, the channels being in flow connection with the radial passages assigned to them. 
     If the physical quantity to be detected includes light waves, a means for delivering the quantity to be detected into the housing interior may be provided in the probe head. In the latter configuration, the means may be a thermally stable light-transmissive aperture, which is seated in a recess of the probe head, at least one cooling channel being provided between the aperture and the wall bounding the recess. In this way, the thermally stable light-transmissive aperture can be cooled particularly simply, which can contribute to its thermal stability. The configuration in which the guide tube and the end section are externally insulated is also advantageous. 
     The end section may be a monolithic part of the guide tube or be fastened thereon. 
     Advantageously, three different media are fed into the probe head, two of which can be conveyed back from the probe head into the guide tube. This requires that there be at least four sections distributed along the axial direction, in which passages distributed over the circumference and extending in the radial direction are accommodated in the guide tube and in the probe head, these being sealed from one another by ring seals arranged between them. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages and features of the invention will be explained in more detail with the aid of an exemplary embodiment. 
         FIG. 1  shows the longitudinal section through a measuring device housing, 
         FIGS. 2 ,  3  respectively show a longitudinal section through the end, receiving a probe head, of a guide tube of the measuring device housing, 
         FIG. 4  shows the cross section through an end section of the guide tube, 
         FIG. 5  shows a longitudinal section through a probe head, 
         FIGS. 6 ,  7 ,  8  show further longitudinal sections through the probe head, and 
         FIGS. 9 ,  10 ,  11  show different probe heads for different detection directions. 
     
    
    
     In all the figures, features which are the same are provided with the same references. 
     DETAILED DESCRIPTION OF INVENTION 
       FIG. 1  schematically shows a measuring device housing  10  in a longitudinal section. The measuring device housing  10 , referred to below merely as the housing  10  for brevity, essentially comprises three components: a coupling apparatus  12 , a guide tube  14  with an end section  16 , and a probe head screwed into the end section  16 . The probe head is not represented in  FIG. 1 . The guide tube  14  extends along a longitudinal axis  20 . Without showing further details in  FIG. 1 , the coupling apparatus  12  is configured in order to feed in total three media  22 ,  24  and  26  into the measuring device housing  10  and deliver them separately to the guide tube  14 . Of the three media, two can be conveyed out again as coolants. The media  22 ,  24 ,  26  are guided separately from one another inside the housing  10  as far as the end section  16  of the guide tube  14 , and are delivered there to the probe head. The design required for this will be explained in more detail in the following figures. 
       FIG. 2  shows the end section  16  of the guide tube  14  as an enlarged detail. The guide tube  14  is configured to be hollow internally, the cavity  28  being used on the one hand to convey back one of the media and on the other hand to accommodate signal transmission lines or sensor lines. An optical fiber or a light waveguide, for example, may be fitted in the cavity  28 . It is also possible to arrange electrical lines of a sensor therein, which sensor is then fitted in the probe head. Whenever the measuring device housing  10  accommodates a sensor or a signal transmission line for or from the sensor, this is also to be understood as a measuring device. 
     The guide tube  14  may furthermore be externally insulated, or heat lagged, although this is not represented. 
     The particular feature of the guide tube  14  is that it is configured to be relatively thick-walled, so that a number of channels  32  are arranged in its wall  30  while being distributed over the circumference, and therefore coaxially with the longitudinal axis  20 . In the longitudinal section (according to  FIG. 2 ), two of these channels  32  are represented, which may be arranged at a 12 o&#39;clock position and at a 6 o&#39;clock position, for example, in relation to the numbers on a clock. Axially extending channels  32  are also respectively provided at different circumferential positions (for example 1 o&#39;clock, 2 o&#39;clock, 3 o&#39;clock, 4 o&#39;clock, 5 o&#39;clock, 7 o&#39;clock, 8 o&#39;clock, 9 o&#39;clock, 10 o&#39;clock, 11 o&#39;clock), so that the different media  22 ,  24 ,  26  can be fed separately from one another through the individual channels  32 . The channels  32  arranged in the guide tube  14  extend from the coupling apparatus  12  into the end section  16  arranged on the guide tube  14 . Those sections of the channels  32  which extend axially in the end section  16  may, for example, be produced by boring, in which case the bore openings may be closed again on the end side by plugs  36 . At different circumferential positions of the corresponding channels  32 , a further bore extending from the outside into the interior of the end section  16  is provided for each channel  32 . Parts of these bores—namely the outer part—are then closed again from the outside by plugs  36 , so that the residual bores then form the radial passages  34  through which the medium flowing in the channels  32  is deviated radially inward. 
     The end section  16  may, for example, be fastened on the guide tube  14  with a material fit by soldering. The end section may, however, also be part of the guide bore  14 . 
     Provided in the end section  16  is an internal screw thread  38  into which a probe head (also not represented in  FIG. 2 ) can be screwed.  FIG. 3  shows the same longitudinal section as  FIG. 2 , but the end section  16  is monolithic, or part of the guide tube  14 . 
       FIG. 3  furthermore represents that the radial passage  34 , which has been produced by boring, is partially closed again from the outside by a plug  36 . It is therefore possible to connect the channel  32  fluidically to the radial passage  34 . 
       FIG. 4  shows the cross section through the end section  16  of the guide tube  14 . One of the channels  32  extending in the axial direction, of which there are twelve in total, is represented every 30°. The screw thread  38  for fastening the probe head  18  is provided inside the guide tube  14 . 
       FIG. 5  shows a first exemplary embodiment of a probe head  18 . The probe head  18  has a first end  40 , on which a screw thread  42  for screwing the probe head  18  into the guide tube  14  is provided. The other axial end of the probe head  18  is referred to as a probe tip  44 . The probe head  18  is configured overall in the form of a sleeve with a cavity  46  on the inside. The tubular wall  48  of the probe head  18  is equipped in a similar way to the guide tube  14  with channels  32  extending in the axial direction, which may likewise be produced by boring. After the boring, some of the bore openings are closed with the aid of plugs  36 . In analogy with the guide tube  14  represented in  FIG. 4 , the probe head  18  also has a corresponding number of cooling channels  32  distributed along the circumference and arranged coaxially with the longitudinal axis  20 . In order to deliver the coolants  22 ,  24 ,  26  provided by the guide tube  14  separately into the probe head  18 , radial passages  34  produced by blind-hole bores are arranged at corresponding axial positions in its wall  48 . With the aid of these passages  34 , different coolants  22 ,  24 ,  26  can be delivered into the probe head  18  in different channels  32 . In order to avoid mixing of the different coolants  22 ,  24 ,  26  during delivery, ring seals  50  are provided between axially neighboring radial passages  34 . In the exemplary embodiment shown, five ring seals  50  are provided. The two outermost ring seals  50  are in this case flanked by guide elements  52  in order to ensure an accurate fit of the probe head  18  in the end section  14 . At the probe tip  44 , the probe head  18  has a recess  54  into which an aperture  56  is fitted. A cooling channel  58  may furthermore be provided between the wall of the recess  54  and the aperture  56 , in order to cool the usually circular aperture  56  with coolant. 
     In the exemplary embodiment of the probe head  18  represented in  FIG. 5 , the viewing direction of the probe head coincides with the longitudinal axis  20 . For this reason, the aperture  56  is oriented perpendicularly to the longitudinal axis  20 . In  FIGS. 6 to 8 , a further exemplary embodiment of the probe head  18  is shown in longitudinal sections lying in different planes. 
     In the further exemplary embodiment, the viewing direction of the probe head is inclined by about 30° relative to the longitudinal axis  20 . The section planes represented in  FIGS. 6 to 8  are respectively offset with respect to one another by an angle of 30°, and therefore correspond to the longitudinal sections of three planes which are spanned by different diameters with the longitudinal axis. For example, the three diameters may in this case lie on different chords: between 1 o&#39;clock and 7 o&#39;clock, between 2 o&#39;clock and 8 o&#39;clock, and between 3 o&#39;clock and 9 o&#39;clock. 
     Likewise as in the first exemplary embodiment of the probe head  18  according to  FIG. 5 , four axially successive sections  60 ,  62 ,  64 ,  66 , which are separated from one another by ring seals  50 , are provided in the second exemplary embodiment of the probe head  18  according to  FIGS. 6 to 8 . In section  60 , cooling air  22  can be fed through the passages  34  ( FIG. 7 ) to the channels  32 . It is subsequently guided to the recess  54 , after which it can be fed out centrally from the probe head  18  through the cavity  46 . Both channels  32  and passages  34  represented in  FIG. 7  are therefore used as feed lines for cooling air  22 , while the cavity  46  is used to discharge the then heated cooling air  22 . 
     In the second axial section  62 , a second medium  24  in the form of so-called “flushing air” can be fed through the radial passage  34  represented in  FIG. 6 . This flushing air is fed through further sections to the aperture  56 , and prevents contamination of the surface of the aperture  56  on the hot gas side. In section  64 , a third coolant  26 , for example cooling water, can be introduced into the probe head  18  in the channel  32  represented in  FIG. 8  (arranged at 9 o&#39;clock). This cooling water  26  subsequently flows to the aperture  56 , flushes it and then flows out of the probe head  18  through the cooling channel  32  represented at the top in  FIG. 8  and the radial passage  34 , which is arranged in the fourth section  66 . The extracted coolant  26  then enters the guide tube  14  again and is guided to the end of the latter on the coupling side. 
       FIGS. 9 to 11  show probe heads  18  for different viewing directions in a perspective representation: a probe head with a viewing angle of 30° is represented in  FIG. 9 , a probe head with a viewing angle of 80° is represented in  FIG. 10 , and the probe head with a viewing angle of 90° is represented in  FIG. 11 . The following features are furthermore represented in  FIGS. 9 to 11 : the axial sections  60 ,  62 ,  64 ,  66 , the sealing rings  50 , the screw thread  42  for screwing the respective probe head  18  into the guide tube  14 , and the radial passages  34  arranged in the different axial sections  60  to  66 . 
     Overall, the present invention provides a measuring device housing  10  for a sensor component which detects a physical quantity contactlessly, or for such a sensor, which comprises: a coupling apparatus  12  for feeding at least one coolant and/or flushing medium  22 ,  24 ,  26  and at least one signal transmission line into the housing interior or into a housing wall, a guide tube  14  arranged on the coupling apparatus  12  and having a longitudinal axis  20 , and a probe head  18  fastened to an end section  16  of the guide tube  14  lying opposite the coupling apparatus  12 , wherein the guide tube  14  is configured in order to guide or accommodate the at least one coolant  22 ,  24 ,  26  and the at least one signal transmission line as far as the probe head  18 . In order to provide a relatively small and compact measuring device, and therefore also a measuring device housing  10  in which different coolants  22 ,  24 ,  26  conveyed in the guide tube  14  can be delivered reliably to different probe heads relatively easily, it is proposed that the probe head  18  and the end section  16  respectively comprise passages  34 , extending radially relative to the longitudinal axis  20  of the guide tube  14  or the probe head  18 , for forwarding the coolant or the coolants  22 ,  24 ,  26  from the end section  16  into the probe head  18  and optionally vice versa.