Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     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. 
     2. Description of the Related Art 
     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. 
     In response to the need for accurate gas flow measurement, ultrasonic flowmeters were developed. Ultrasonic flowmeters, also named sonic or acoustic flowmeters, revolutionized the gas industry because of their many advantages. For example, 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 can also measure gas flow accurately despite changing gas composition. 
     FIG. 1 shows a prior art 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  114 - 117  (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 outside of holder sleeve  140  is union sleeve  150 . Sleeve  150  is not removable from holder sleeve  140 . On the outer diameter (OD) of union sleeve  150  are 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. 
     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. 
     For removal of the transducer holder and transducer, first the mount cover is removed. The extractor tool (not shown) is then attached to the transducer mount. 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 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 the 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. 
     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. 
     The large size of the current T-slot transducer mount provides certain drawbacks. Specifically, the current transducer mount 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. 
     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. Despite the apparent advantages of such a transducer mount, to date no such mount has been commercially introduced. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an improved ultrasonic transducer mount. Unlike prior transducer mounts, the improved transducer mount includes a removable union sleeve with an outer diameter (OD) that engages the inner diameter (ID) of the extractor tool union nut. A retaining ring holds the union sleeve in place on the outside of a transducer holder sleeve. The union sleeve and the retaining ring need only be used with the extractor tool for removal of the transducer. 
     According to an exemplary embodiment, the union sleeve fits over a holder sleeve on the mount. The holder sleeve has at least one flat surface that engages a similar configuration on the ID of the union sleeve. The flat surface(s) prevent(s) relative rotation between the union sleeve and holder sleeve after installation on the mount and during engagement and disengagement of the extractor tool. 
     The end of the union sleeve contacting the retaining ring includes a counter bore on the contacting face. The counter bore fully circumscribes the retaining ring when the union nut pulls the union sleeve against the retaining ring during engagement. This counter bore prevents inadvertent disassembly of the retaining ring from the groove if the extractor tool valve rotates as the union nut engages. Inadvertent disassembly occurs because rotation of the extractor tool valve rotates the union seal of the valve assembly and this rotation may un-spiral the retaining ring from its groove. 
     The design of the union sleeve, the counter bore on the end of the union sleeve, retaining ring, retaining ring groove, and the placement of the retaining ring groove on the mount are designed so that when the union nut and union seal of the extractor tool valve engage the mount, the retaining ring is compressed by the surface on the bottom of the counter bore on the end of the union sleeve and the end of the union seal. The compression of the retaining ring prevents the retaining ring from becoming canted within the groove as the pressure and other forces pull on the extractor tool assembly. By keeping the retaining ring perpendicular to the OD in the groove, the strength of the retaining ring and groove are greatly increased and wear is minimized. 
     With a removable union sleeve, the mount base can be smaller in size. This is because less clearance is required around the union sleeve threads for the cap screws that 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, two mount cover retaining brackets connect to the mount base and are located 180° apart. The retaining brackets have screw holes for attachment of the mount cover by the mount cover screws. The retaining brackets also act as jackscrew holes eliminating the need for the holes on mount base. When the cover and mount base attachment means have been removed, the threaded holes in both of the retaining brackets receive the jackscrews. When the jackscrews tighten, the screws engage the meter housing and force the mount from the housing. The brackets thus also eliminate the need to provide additional holes solely for jackscrews. 
     Because the new design mount does not include a permanent OD surface for engagement with the extractor tool, the mount base can be made much smaller. 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 also decreases the casting weight of the housing casting with the use of smaller housing transducer location bosses. The smaller transducer mount also decreases the end to end length of the small size meter housing. The smaller transducer mount also allows location of the transducer ports in the housing in the same location for different pressure rating transducer mounts. The smaller transducer mount, however, it still compatible with existing transducers and transducer holders. 
    
    
     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 sell 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 
     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
     FIG. 1 is an illustration of a prior art transducer mount; 
     FIG. 2 is a perspective view of a transducer mount constructed in accordance with the preferred embodiment without a union sleeve attached; 
     FIG. 2A is atop view of the transducer mount of FIG. 2; 
     FIG. 2B is a cross-sectional view of the transducer mount of FIG. 2; 
     FIG. 3 is a perspective view of the transducer mount of FIG. 2 with a union sleeve attached; 
     FIG. 3A is a top view of the union sleeve of FIG. 3; 
     FIG. 3B is a cross-sectional view of the union sleeve of FIG. 3; 
     FIG. 4 is a perspective view of the transducer mount of FIG. 2 with the mount over shown; 
     FIG. 5 is a cross-sectional view of a transducer mount extractor tool valve attached to a transducer mount constructed in accordance with the preferred embodiment; 
     FIG. 5A is a perspective view of the transducer mount extractor tool valve of FIG. 5 attached to a transducer mount constructed in accordance with the preferred embodiment; 
     FIG. 6 is a perspective view of a first alternative embodiment transducer mount to the preferred embodiment shown in FIG. 2; 
     FIG. 6A is a top view of the first alternative embodiment transducer mount of FIG. 6; 
     FIG. 6B is a cross-sectional view of the first alternative embodiment transducer mount of FIG.  6 ; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIGS. 2,  2 A, and  2 B, transducer mount  200  constructed in accordance with the preferred embodiment will now be described. The mount  200  comprises a base  210  that includes a side surface  211  and a flat surface  212 . Arcuately located in the base  210  are cap screw holes  213 - 218  for receiving cap screws (not shown). According to the preferred embodiment, slits  225 - 230  are made in the side surface  211  of base  210 . Each slit has two opposing surfaces, one parallel to the flat surface  212  of the mount base  210  and the other angled to the first surface. The slits  225 - 230  preferably are sized to accommodate the flat blade of a screw driver or other pry bar tool to facilitate removal of the mount  200  from a housing (not shown). The slits  225 - 230  may not be suitable to completely remove the mount  200  from the housing, but preferably are sufficient to provide a gap between the mount  200  and the housing. The gap would then allow the use of a pry bar tool to pry the mount  200  completely free of the housing. The slits  225 - 230  thus eliminate the need for jackscrew holes in the mount  200 . 
     Located on the mount base  210  are two mount cover bracket channels  230 ,  231  located 180° apart. Mount cover brackets  233 ,  234  fit within the mount cover bracket channels  230 ,  231  respectively. Mount cover brackets  233 ,  234  preferably include bracket holes  235 ,  236  and bracket mount cover holes  237 ,  238  respectively. Mount cover brackets  233 ,  234  eliminate the need for mount cover holes in the mount base  210 . They also may be used as jackscrew holes, if necessary. Screws  239 ,  240  engage bracket holes  235 ,  236 , respectively, and attach the brackets  233 ,  234  to the mount cover bracket channels  230 ,  231 . 
     Holder sleeve  250  extends from mount base  210 . Holder sleeve  250  sealingly engages with the transducer holder and transducer during operation. Located on the OD of holder sleeve  250  are flat surfaces  251 - 256 . Also located on holder sleeve  250  is a groove  257  for engagement with a union sleeve retaining ring (not shown). In operation, cap screws (not shown) attach the mount  200  to a meter housing (not shown). The transducer and transducer holder are then inserted into the holder sleeve  250 . 
     Referring now to FIGS. 3,  3 A, and  3 B, transducer mount  300  and removable union sleeve  310  constructed in accordance with the preferred embodiment will now be described. The union sleeve  310  slidingly engages holder sleeve  330 . Union sleeve  310  is only placed on holder sleeve  330  when used with the extractor tool to remove the transducer and transducer holder. The ID of union sleeve  310  has flat surfaces  311 - 316  that engage the corresponding flat surfaces on the OD of the holder sleeve as shown in FIG.  2 . The engagement of the flat surfaces  311 - 316  prevents relative rotation between the union sleeve and holder sleeve after installation on the mount and during engagement and disengagement of the extractor tool. The number and configuration of the flat surfaces may be altered without departing from the spirit of the present invention. The union sleeve has a counter bore  317  on the flat side  318  facing out from the mount base. Counter bore  317  engages retaining ring  319  held in place by retaining ring groove (shown in FIG. 2) on holder sleeve  330 . The OD of union sleeve  310  has threads  320  that engage the ID threads of the union nut (not shown) of the extractor tool valve during removal of the transducer and transducer holder. 
     Referring now to FIG. 4, transducer mount  400  and transducer mount cover  410  constructed in accordance with the preferred embodiment will now be described. The transducer mount cover  410  holds the transducer holder in place on the meter housing (not shown) and prevents inadvertent disassembly during use. The transducer mount cover  410  includes two holes  411 ,  412  located 180° apart on the edge of the cover  410 . Screws  413 ,  414  attach the cover  410  to the mount  400  by engaging the mount cover holes  411 ,  412  and the bracket mount cover holes  401 ,  402 . 
     Referring now to FIGS. 5 and 5A, transducer mount  500  and extractor tool valve  520  attached to the union sleeve  510  constructed in accordance with the preferred embodiment will now be described. The extractor tool valve  520  has a union nut  530  disposed on one end. The union nut  530  has internal threads  531  and attaches to the union sleeve  510  by threading the union nut  530  onto the union sleeve  510 . Once threaded, the union nut  530  and union sleeve  510  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  500  through the extractor tool valve  520  and into a chamber in the extractor tool removable unit (not shown) that attaches to flange  521  on extractor tool valve  520 . Once the transducer holder and transducer are removed and placed in the removable unit, the chamber is sealed from the mount  500 . The transducer and transducer holder can then be removed from the extractor tool valve  520 . 
     Referring now to FIGS. 6,  6 A, and  6 B, an alternative embodiment to the present invention will now be discussed. Mount  600  has the same features and operates the same way as the main embodiment except for the means attaching the mount cover to the mount. Located 180° apart on the mount base  610  are two retaining bosses  620 ,  630  pressed into holes  613 ,  614  in the side surface  611  of the mount base  610 . The retaining bosses  620 ,  630  have a small end  621 ,  631  and a large end  622 ,  632 . The retaining bosses  620 ,  630  have flat faces  623 ,  633  on the surface of the large end  622 ,  632 . On this flat face  623 ,  633 , boss mount cover attachment holes  624 ,  634  are machined prior to installation. The retaining bosses  620 ,  630  have knurls on the surface of the small ends  621 ,  631 . The small ends  621 ,  631  are pressed into holes  613 ,  614  in the mount base side surface  611  with the boss mount cover attachment holes  624 ,  634  in the needed position. A fixture aligns the flat faces  623 ,  633  on the retaining bosses  620 ,  630  to the base of the mount  610 . Alternatively, when the mount  600  is investment cast, the retaining bosses  620 ,  630  can be cast as part of the mount  600  and the boss mount cover holes  624 ,  634  machined into the cast bosses  620 ,  630 . 
     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.

Technology Category: 3