Abstract:
The present invention comprises an improved ultrasonic transducer mount including a transducer holder sleeve, a base attachment sleeve, and a removable mount cover attachment ring. The transducer holder sleeve has an outer surface that engages an extractor tool for removal of the transducer and transducer holder from the mount. The base attachment sleeve has an outer surface that engages a housing for attachment of the transducer mount.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    The present invention relates generally to meters that measure the flow of a fluid. More particularly, the present invention relates to ultrasonic meters measuring fluid flow through a pipe. Still more particularly, the present invention relates to a structure for mounting transducers to an ultrasonic flow meter.  
           [0005]    2. Description of the Related Art  
           [0006]    After a hydrocarbon, such as natural gas, has been removed from the ground, it is often transported from place to place via pipelines. Very often, an owner or operator of a pipeline desires to accurately know how much gas is flowing through the pipeline. For example, where a billion standard cubic feet of natural gas flows through a single pipeline, even small percentage errors can result in serious miscalculations regarding the amount of gas flowing through the pipeline. Further, particular accuracy for the measurement is demanded when gas is changing hands, or “custody”, because custody transfer applications often involve the exchange of money. Even so, an accurate meter is desirable for all phases of gas or fluid production, transportation, and distribution operations, and for off-shore platforms.  
           [0007]    In response to the need for accurate gas flow measurement, ultrasonic flowmeters were developed. Ultrasonic flowmeters, also named sonic or acoustic flowmeters, have the potential to greatly improve the accuracy of gas flow measurements. Unlike many other flowmeter technologies, ultrasonic flowmeters are accurate over a large range of flow rates. Because ultrasonic gas flowmeters are non-intrusive, gas flows through the gas pipeline without encountering an increased pressure region. Consequently, considerable savings are achieved because the gas flows more easily in the pipe. In addition, ultrasonic flowmeters also can measure gas flow accurately despite changing gas composition.  
           [0008]    [0008]FIG. 1 shows a prior art T-slot ultrasonic transducer mount  100 . The mount  100  includes a base  130  with a side surface  131  and a flat surface  132 . Arcuately located on the base flat surface  132  are cap screw holes  110 - 113  for receiving cap screws (not shown) respectively. Also located on base flat surface  132  are two jackscrew holes  120 ,  121  located 180° apart for receiving jackscrews (not shown). The jackscrews are used for removal of the mount from the meter housing. Also located on the base flat surface  132  are two mount cover holes  118 ,  119  located 180° apart for receiving the mount cover screws (not shown). Extending from the base  130  is a holder sleeve  140 . The inner diameter (ID) of the holder sleeve  140  engages a transducer holder that holds a transducer (not shown). On the outer diameter (OD) of holder sleeve  140  are union sleeve threads  151  for engagement with a union nut (not shown). The union nut is part of an extractor tool (not shown) for removal of the transducer holder and transducer.  
           [0009]    In operation, the cap screws (not shown) attach the mount  100  to a meter housing (not shown). The transducer and transducer holder are then inserted into the holder sleeve  140 . Once inserted, the transducer holder forms a fluid-tight seal at the joint with the holder sleeve. A mount cover (not shown) attaches to the mount base with screws that engage the mount cover holes  118 ,  119 . The mount cover locks the transducer holder in place and prevents inadvertent disassembly during use and electrical connection to the transducer.  
           [0010]    For removal of the transducer holder and transducer, first the mount cover is removed. An extractor tool (not shown) is then attached to the transducer mount  100 . The extractor tool consists of an extractor tool valve (not shown) and a removable unit for isolation of the transducer holder and transducer from the transducer mount and meter housing. The extractor tool attaches to the transducer mount  100  by the extractor tool valve union nut (not shown) engaging the union sleeve threads  151 . Once engaged, the extractor tool makes an fluid-tight seal with a union valve seal. This seal allows removal of the transducer holder and transducer without releasing pressure from the meter housing and pipeline. The transducer and transducer holder are then removed from the holder sleeve  140  through the extractor tool valve and placed in a chamber in the extractor tool removable unit. Once the transducer holder and transducer are removed, the chamber is sealed from the holder sleeve. Once sealed, the transducer and transducer holder can be removed from the extractor tool.  
           [0011]    For removal of the transducer mount  100 , pressure must be vented from the housing and the cap screws (not shown) must be removed. Jackscrews are then inserted into jackscrew holes  120 ,  121 . As the screws draw into the holes, they engage the meter housing surface. Further drawing the screws into the jackscrew holes forces the mount  100  out of engagement with the meter housing.  
           [0012]    The large size of the T-slot transducer mount provides certain drawbacks. Specifically, the current transducer mount of FIG. 1 causes problems with small meter housings. For example, the cast bosses for the very large OD transducer mounts greatly increase the casting weight of the housing casting because of the material needed at each transducer location boss to allow the mount to be attached. The housing transducer location bosses for the very large OD mounts also greatly increase the end to end length of the meter housing. The increased length is a major concern because the bore of the meter must be machined. The ability to machine a small ID over a very long length becomes harder as the length increases. This is true even if the bore is machined from each end. There are also cost issues concerned with the large size transducer mounts because of the large amount of material used.  
           [0013]    Another transducer mount is disclosed in the patent application U.S. Ser. No. 09/944,268 entitled “Ultrasonic Flowmeter Transducer Mount” filed Aug. 30, 2001. This transducer mount includes a removable union sleeve with an outer diameter (OD) that engages the inner diameter (ID) of the extractor tool union nut. The union sleeve fits over a holder sleeve on the mount. With a removable union sleeve, the mount base can be smaller in size because less clearance is required around the union sleeve threads for the cap screws that attach the mount base to the meter housing. The mount base, however, still must be attached to the meter housing with the cap screws as in the T-slot design. Also, the mount must have a reliable means for attaching the union sleeve to the holder sleeve.  
           [0014]    It would be advantageous to design a transducer mount that is smaller in size than conventional designs, and that can be manufactured more inexpensively. Ideally, the new transducer mount would be compatible with existing extractor tools, transducers, and holders to facilitate a smooth transition to the new mount design. The new transducer mount would also allow for a smaller size meter housing than conventional meter housings. The smaller size meter housing would have a decreased casting weight and a decreased end to end length. It would also be advantageous to locate the transducer ports in the housing in the same location for different pressure rating transducer mounts. It would also be advantageous for the transducer mount to attach easily to the meter housing. Despite the apparent advantages of such a transducer mount, to date no such mount has been commercially introduced.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention comprises an improved ultrasonic transducer mount. Unlike prior transducer mounts, the improved transducer mount includes a threaded base sleeve for attachment to the meter housing, a mount base, and a holder sleeve. With the threaded base sleeve, the mount base can be smaller in size. This is because the mount does not require cap screws to attach the mount base to the meter housing. With the mount base smaller, the mount cover is too big for direct attachment. To attach the mount cover, a mount cover ring connects to the holder sleeve. The mount cover ring has screw holes for attachment of the mount cover by the mount cover screws.  
           [0016]    The reduced mount size reduces cost by reducing the material needed. The reduced size also saves manufacturing costs with the ability to be investment cast. The smaller transducer mount decreases the casting weight of the housing with the use of smaller housing transducer location bosses. The smaller transducer mount decreases the end to end length of the small size meter housing. The smaller transducer mount allows the transducer ports to be situated in the same housing location, regardless of the pressure rating. The smaller transducer mount, however, it still compatible with existing transducers and transducer holders.  
           [0017]    Thus, the present invention comprises a combination of features and advantages which enable it to overcome various problems of prior devices. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein:  
         [0019]    [0019]FIG. 1 is an illustration of a prior art transducer mount;  
         [0020]    [0020]FIG. 2A is a cross-sectional side view of a transducer mount constructed in accordance with the preferred embodiment;  
         [0021]    [0021]FIG. 2B is a cross-sectional side view of a mount cover ring constructed in accordance with the preferred embodiment;  
         [0022]    [0022]FIG. 2C is a top view of the outer perimeter of the transducer mount base constructed in accordance with the preferred embodiment;  
         [0023]    [0023]FIG. 3 is a perspective view of the mount constructed in accordance with the preferred embodiment with the mount cover ring attached and the mount cover shown;  
         [0024]    [0024]FIG. 4 is a cross-sectional view of the mount constructed in accordance with the preferred embodiment with the extractor tool attached; and  
         [0025]    [0025]FIG. 4A is a perspective view of the mount constructed in accordance with the preferred embodiment with the extractor tool attached.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    Referring initially to FIGS. 2A, 2B, and  2 C, transducer mount  200  constructed in accordance with the preferred embodiment will now be described. The mount  200  comprises a substantially cylindrical base  202  that is received in a meter housing (not shown). The base  202  includes an inner bore  204  that extends from one end of the mount to the other. The inner bore  204  has a diameter that is substantially constant. The base inner bore  204  sealingly receives the transducer holder and transducer (not shown) during operation. The base  202  includes an outer surface  206 .  
         [0027]    The transducer and transducer holder are inserted into a mount holder sleeve  210  that extends from the mount base  202 . The holder sleeve  210  includes an outer surface  212 . The holder sleeve outer surface  212  has extractor tool threads  214  that engage the inner surface threads of the union nut (not shown) of the extractor tool valve during removal of the transducer and transducer holder. The holder sleeve seal surface  216  provides a seal surface for the extractor tool union valve seal (not shown).  
         [0028]    The mount  200  also includes a base sleeve  218  with an outer surface  220 . The base sleeve outer surface  220  includes threads  220  for attaching the base to the meter housing. During operation, the mount  200  forms a fluid-tight seal with the meter housing with an o-ring seal  222  positioned in a groove  224 . Referring specifically to FIG. 2C, the base outer surface  206  includes four flat surfaces  208  for engagement with a tool such as a wrench for threading the mount  200  into the meter housing.  
         [0029]    Referring now specifically to FIG. 2B, a mount cover attachment ring  226  constructed in accordance with the preferred embodiment will now be discussed. Mount cover attachment ring  226  has an outer surface  228  and an inner surface  230 . The attachment ring also has mount cover ring holes  232 ,  234  for receiving mount cover attachment screws (not shown). Previous-style mount covers require mount cover holes at a certain distance apart to receive the mount cover screws for attaching the mount cover to the mount. With the mount  200  being smaller in size compared to previous mounts, the mount cover attachment ring  226  provides the mount cover ring holes  232 , 234  at the same distance apart as the previous mounts. The inner surface  230  of the attachment ring  226  also has threads  236  that engage the extractor tool threads  214  on the holder sleeve outer surface  212 . For attachment, ring  226  is threaded onto the holder sleeve outer surface  212 .  
         [0030]    Referring now to FIG. 3, transducer mount  300  and transducer mount cover  310  constructed in accordance with the preferred embodiment will now be described. The transducer mount cover  310  holds the transducer holder in place on the meter housing (not shown) and prevents inadvertent disassembly during use. The transducer mount cover  310  includes two holes  311 ,  312  located 180° apart on the edge of the cover  310 . Screws attach the cover  310  to the mount  300  by engaging the mount cover holes  311 ,  312  and the mount cover ring holes  301 ,  302 .  
         [0031]    Referring now to FIGS. 4 and 4A, transducer mount  400  and extractor tool valve  420  constructed in accordance with the preferred embodiment will now be described. The extractor tool valve  420  has a union nut  430  disposed on one end. The union nut  430  has internal threads  431  and attaches to the holder sleeve  410  by threading the union nut  430  onto the holder sleeve  410 . Once threaded, the union nut  430  and holder sleeve  410  form a fluid-tight seal. This seal allows removal of the transducer holder and transducer without releasing pressure from the meter housing and pipeline. For removal, the transducer and transducer holder are extracted from the mount  400  through the extractor tool valve  420  and into a chamber in the extractor tool removable unit (not shown) that attaches to flange  421  on extractor tool valve  420 . Once the transducer holder and transducer are removed and placed in the removable unit, the chamber is sealed from the mount  400 . The transducer and transducer holder can then be removed from the extractor tool valve  420 .  
         [0032]    While preferred embodiments of this invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims which follow, the scope of which shall include all equivalents of the subject matter of the claims.