Abstract:
A connector arrangement comprises a rigid inner conductor ( 107 ), a dielectric sleeve ( 111 ) arranged around the inner conductor and a rigid outer conductor ( 109 ) arranged around the sleeve. A surface of at least one of the inner conductor, the sleeve and the outer conductor is provided with a taper, such that the sleeve fixes the relative transverse positions of the inner and outer conductors at a first end of the arrangement and not at a second end of the arrangement. The inner conductor is longitudinally slidable relative to the outer conductor. Such an arrangement is suitable for use in hostile environments, such as in high temperature pipelines, in which there are large temperature variations and in which the positional variation of mating connectors is high.

Description:
CROSS-REFERENCE 
       [0001]    Applicant claims priority from Great Britain patent application GB 0722273.0 filed 13 Nov., 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a connector arrangement having an inner conductor and an outer conductor. In particular, this invention relates to a connector arrangement of this type which is suitable for use in hostile environments subject to large temperature variations and/or in applications in which there is significant variation in the relative positions of the components of mating connectors. 
         [0003]    Connectors having separate inner and outer conductors, such as coaxial connectors, may be used to provide a shielded connection between passive or active electrical and electronic elements. 
         [0004]    Frequently, such connectors are used in hostile environments which are subject to large temperature variations and in applications in which the positional variation of mating connectors is high. An example of such an environment is a high temperature pipeline monitoring arrangement, whereby an antenna embedded in the wall of a pipeline is connected to electronic monitoring equipment. Such an arrangement may operate at temperatures of up to 250° C. for prolonged periods of time. 
         [0005]    There is thus a need for connectors for use in such applications, which connectors are preferably capable of providing reliable electrical connections. 
       SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect of the invention, there is provided a-connector arrangement comprising a rigid inner conductor, a dielectric sleeve arranged around the inner conductor and a rigid outer conductor arranged around the sleeve, wherein a surface of at least one of the inner conductor, the sleeve and the outer conductor is provided with a taper, such that the sleeve fixes the relative transverse positions of the inner and outer conductors at a first end of the arrangement and not at a second end of the arrangement, and wherein the inner conductor is longitudinally slidable relative to the outer conductor. 
         [0007]    The invention thus provides a connector arrangement which can accommodate both longitudinal and transverse misalignment of mating connectors, and which can cope with the differential expansion of components as caused by temperature variations in materials having different temperature coefficients of expansion. 
         [0008]    In relation to the invention, the term “longitudinal” refers to a direction substantially parallel to the main axis of the inner conductor. The term “transverse” refers to any direction substantially perpendicular to the main axis of the inner conductor. 
         [0009]    The first end of the connector arrangement is typically for connection to a coaxial cable terminated in a conventional connector. In this case, the inner conductor may terminate in a compliant socket and the outer conductor may terminate in a threaded sleeve. 
         [0010]    The second end of the connector arrangement is for connection to one or more conductors of a mating connector which may be misaligned relative to each other or other components such as housings and casings. The misalignment may be longitudinal, transverse, or both longitudinal and transverse. 
         [0011]    The inner conductor is slidable within the outer conductor, and this allows for their relative longitudinal positions to be adjusted to suit the mating connector. 
         [0012]    The inner and outer conductors may be coaxially arranged at the first end of the arrangement, and held in this arrangement by the interposed dielectric sleeve. The inner conductor, and optionally also the dielectric sleeve, have a floating transverse arrangement relative to the outer conductor at the second end of the arrangement. It is this floating arrangement which allows for the transverse misalignment mentioned above. 
         [0013]    The inner and outer conductors are preferably reversibly separable, i.e. they may be separated and then reassembled. Thus, the inner conductor may initially be coupled to the mating connector in isolation, with the sleeve and outer conductor subsequently being assembled over the inner conductor. The dielectric sleeve may be permanently attached to the outer conductor for this purpose. The outer conductor may or may not be arranged for coupling to the mating connector. 
         [0014]    In preferred embodiments, the inner conductor is provided at the second end of the arrangement with a plurality of longitudinal connector elements having resilience in a transverse direction. These connector elements provide for electrical and mechanical coupling of the inner conductor with the mating connector, particularly a cylindrical bore of the mating connector. Specifically, in the coupled configuration, the connector elements resiliently bear in transverse directions against the wall of the cylindrical bore. 
         [0015]    The connector elements may define a split pin arrangement, such as a bifurcated split pin arrangement. In this case, the connector elements are arranged to bear in opposite directions against the wall of the cylindrical bore of the mating connector. 
         [0016]    The connector elements may have an outwardly curved, or barreled, outer surface for defining a single longitudinal point of contact with the wall of the cylindrical bore of the mating connector. In this way, the pressure applied by the connector elements is maximised to ensure a reliable electrical connection. Such an outer surface also allows for angular misalignment with the mating connector. 
         [0017]    The connector elements may be transversely spaced apart in their unbiased configuration, and are arranged such that they may be biased directly against each other, particularly so that their distal ends bear against each other. In this way, the force with which the outer surfaces bear on the wall of the cylindrical wall of the mating connector may be maximised. 
         [0018]    The inner conductor may be further provided, at or near the second end of the arrangement, with a transverse flange for longitudinally locating the inner and/or outer conductor. Similarly, the outer conductor may be provided, at the first end of the arrangement, with a transverse flange for mounting the arrangement to a housing or enclosure. 
         [0019]    The invention also provides an antenna connector and a pipeline antenna connector comprising the connector arrangement described above. 
         [0020]    Also disclosed is a pipeline antenna assembly comprising: an insert for mounting in a wall of a pipe; an antenna mounted in a surface of the insert; and the connector arrangement described above, wherein the inner conductor is connected at the second end of the arrangement to the antenna. 
         [0021]    The pipeline antenna assembly is for mounting in the wall of a pipeline, such as a high temperature pipeline, such that the antenna is able to transmit and/or receive signals travelling within the pipeline. 
         [0022]    According to a second aspect of the invention, there is provided a method of coupling a connector arrangement to a mating connector, the method comprising: coupling a rigid inner conductor to a conductor of the mating connector; and assembling a dielectric sleeve and a rigid outer conductor around the inner conductor such that the sleeve is interposed between the inner and outer conductors, wherein a surface of at least one of the inner conductor, the sleeve and the outer conductor is provided with a taper, such that the sleeve fixes the relative transverse positions of the inner and outer conductors at a first end of the arrangement and not at a second end of the arrangement. 
         [0023]    The connector arrangement in the second aspect may be the connector arrangement of the first aspect described above. 
         [0024]    The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0025]    A specific embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0026]      FIG. 1  is a cross sectional view of a pipeline antenna assembly which includes a connector arrangement according to the invention; 
           [0027]      FIG. 2  is a detailed cross sectional view of the connector arrangement shown in  FIG. 1 ; and 
           [0028]      FIGS. 3A to 3D  are cross sectional views for explaining the process by which the connector arrangement shown in  FIGS. 1 and 2  is coupled with a mating connector. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    The invention provides a connector arrangement comprising a rigid inner conductor, a dielectric sleeve arranged around the inner conductor and a rigid outer conductor arranged around the sleeve. A surface of the inner conductor, the sleeve and/or the outer conductor is provided with a taper, such that the sleeve fixes the relative transverse positions of the inner and outer conductors at a first end of the arrangement and not at a second end of the arrangement. In this way, the inner conductor can cope with transverse misalignment in corresponding conductors of mating connectors. The inner conductor is longitudinally slidable relative to the outer conductor, so as to allow for longitudinal misalignment between corresponding conductors of mating connectors. 
         [0030]    The invention also provides a method for coupling the connector arrangement with a mating connector. 
         [0031]      FIG. 1  is a cross sectional view of a pipeline antenna assembly  1  comprising a connector arrangement  101  according to the invention. The assembly  1  forms part of a pipeline monitoring system, which system may be provided for determining the content of the pipeline and its flow rate. 
         [0032]    The assembly  1  comprises a substantially cylindrical insert  3  for mounting in the wall of a pipeline. The insert  3  is arranged such that, once installed in the pipeline, its front F end  5  is substantially flush with an inner surface of the pipeline wall and its rear R end  7  is substantially flush with the outer surface of the pipeline. 
         [0033]    The insert  3  is formed as a solid metal component through which a cylindrical bore  9  is provided. The cylindrical bore  9  extends the full length of the insert  3  from the front end  5  to the rear end  7  and is provided for accommodating certain components of the pipeline monitoring system. 
         [0034]    In particular, an antenna  11  is mounted within the cylindrical bore  9  at the front end  5  of the insert  3 . The antenna  11  is mounted in the bore  9  such that it projects from the front end  5  of the insert  3  to enable signals to be transmitted and/or received in the pipeline. The antenna  11  is hermetically sealed into the bore  9  with a glass bead. A rear end of the antenna  11  is itself provided with a cylindrical bore  13  to serve as a connector for the antenna  11 . 
         [0035]    By reason of its installation process, the longitudinal (parallel to axis  14 ) and transverse (radial to axis  14 ) positioning of the antenna  11  within the cylindrical bore  9  varies significantly between different assemblies  1 . For this reason, and by reason of the depth of the antenna  11  within the bore  9 , it is not generally possible to couple conventional electrical cables directly to the antenna connector in bore  13 . 
         [0036]    Accordingly, the insert  3  is additionally provided with the connector, arrangement  101  according to the invention. The connector arrangement  101  is mounted to the insert  3  and at one end provides an electrical connection to the antenna connector  13  and at its other end is terminated with a coaxial connector  103  for the antenna  11 , which connector  103  is externally mounted to the rear R end  7  of the insert  3 . 
         [0037]    The externally mounted coaxial connector  103  thus provides a convenient means for coupling conventional electrical cables (not shown) to the antenna  11  shown. 
         [0038]    The mounting position of the coaxial connector  103  is fixed relative to the cylindrical bore  9 , and does not vary between different assemblies  1 . Since the position of the antenna  11  within the cylindrical bore  9  varies significantly between different assemblies  1  (see above), one of the functions of the connector arrangement  101  is to accommodate variations in the relative positions of the antenna  11  and the coaxial connector  103 . 
         [0039]    The connector arrangement  101  is shown in more detail in  FIG. 2 , which is a cross sectional view. A first end of the arrangement  101  is provided with the coaxial connector  103  and a second end of the arrangement  101  is provided with a pair of connector elements  105  for connection to the antenna connector  13 . 
         [0040]    Referring to  FIG. 2 , the connector arrangement  101  comprises a cylindrical inner conductor  107  and a tubular outer conductor  109  (not fully shown) each formed of a metallic material. Interposed between the inner and outer conductors  107 ,  109  is a dielectric sleeve  111  which physically separates the conductors  107 ,  109 . The surfaces of the inner and outer conductors  107 ,  109  and the dielectric sleeve  111  each have a circular cross section. 
         [0041]    An inner surface or bore  112  of the dielectric sleeve  111  is provided with a straight taper, such that its diameter is greater at the front end of the arrangement  101  than at the rear end of the arrangement  101  and it is gradually tapered between its ends. Consequently, the dielectric sleeve  111  maintains the inner and outer conductors  107 ,  109  coaxially at the rear end of the arrangement  101 , while the axis of the inner conductor  107  is allowed to float somewhat relative to the axis of the outer conductor  109  at the front end of the arrangement  101 . 
         [0042]    The dielectric sleeve  111  and the outer conductor  109  are mechanically coupled such that they are not movable relative to each other. In particular, steps  113 ,  115  formed in their facing surfaces cooperate to prevent relative longitudinal movement. 
         [0043]    In contrast, the dielectric sleeve  111  and the inner conductor  107  are not mechanically coupled to fix their relative longitudinal positions. Thus, the inner conductor  107  is slidably arranged within the dielectric sleeve  111 . 
         [0044]    As mentioned above, the rear end of the arrangement  101  is provided with a coaxial connector  103 . The coaxial connector  103  comprises a compliant socket  117  formed out of an end of the inner conductor  107  and a threaded sleeve  119  formed out of the end of the outer conductor  109 . The threaded sleeve  119  protrudes beyond the dielectric sleeve  111 . 
         [0045]    The first end of the arrangement  101  is also provided with a circumferential flange  121  (shown only in  FIG. 1 ) for mounting the arrangement  101  to the insert  3 . The flange  121  is part of the outer conductor  109 . 
         [0046]    The front end of the arrangement  101  is provided with a pair of connector elements  105  in the form of a bifurcated split pin for connection to the antenna connector  13 . The connector elements  105  are formed out of an end of the inner conductor  107  and protrude beyond the dielectric sleeve  111  and the outer conductor  109 . The protruding portion of the inner conductor  107  is also provided at the second end of the arrangement with a circumferential flange  123  for use in longitudinally locating the outer conductor  109 . 
         [0047]    The connector elements  105  of the connector arrangement  101  are shown in more detail in  FIGS. 3A to 3D , which are cross sectional views. As mentioned above, the connecting elements  105  are in the form of a bifurcated split pin. The elements  105  thus extend in the longitudinal direction and are transversely spaced apart. The outer surfaces  106  of the elements  105  define an outwardly curved or barreled surface, with diameters tapering to be of progressively smaller diameter both forward F and rearward R of a largest diameter location  110 . The inwardly facing surfaces  108  of the elements  105  define parallel flat surfaces. The barreled outer surface provides for a reliable electrical connection and accommodates angular misalignment between the connector elements  105  and the primarily cylindrical bore  112  of the antenna connector  13 . Rear ends  114 R of halves  114  of the elements are separated by a distance d. 
         [0048]    The front ends  114 F of the elements  105  are provided with chamfered outer edges for guiding the elements  105  into the antenna connector  13 , as shown in  FIGS. 3A and 3B . 
         [0049]    The connector elements  105  are shaped such that when they are inserted into the antenna connector  113 , they are resiliently urged towards each other by the wall of the mating connector, so that they apply an opposite transverse force on the wall of the antenna connector  113 , as shown in  FIGS. 3B and 3C . The elements  105  are also arranged such that they continue to be urged towards each other after their distal ends have touched, as shown in  FIG. 3D . In this way, the elements  105  may apply very high forces on the wall of the antenna connector  113 . There is a longitudinal distance D between the largest diameter locations  110  of the connector and their front ends  114 F where D is a plurality of times as great as d. 
         [0050]    In use, the inner conductor  107  ( FIG. 2 ) of the arrangement  101  is initially separated from the dielectric sleeve  111  and the outer conductor  109 . The inner conductor  107  is then inserted front end first, into the cylindrical bore  9  ( FIG. 1 ) of the insert  3 . The connector elements  105  enter the antenna connector  13 , as shown in  FIG. 3A and 3B , and engage with the wall of the antenna connector  13 , as shown in  FIGS. 3C and 3D . 
         [0051]    The inner conductor  107  is located longitudinally using the rear end  7  ( FIG. 1 ) of the insert  3  as a datum, and the resilience of the connector elements  105  ( FIG. 3D ) maintains the inner conductor  107  in this location. 
         [0052]    Subsequently, the dielectric sleeve  111  ( FIG. 2 ) and the outer conductor  109 , which are mechanically coupled to each other, are assembled around the inner conductor  107  by sliding them over the inner conductor  107 . The outer conductor  109  is located longitudinally using the circumferential flange  123  extended from the inner conductor  107  at the front end of the arrangement  101 , and using the circumferential flange  121  ( FIG. 1 ) extended from the outer conductor  109  at the first end of the arrangement  101  to limit insertion depth. 
         [0053]    The circumferential flange  121  extended from the outer conductor  109  at the first end of the arrangement  101  is then mechanically attached to the rear end  7  of the insert  3  using screw fasteners, so as to transversely and longitudinally locate the first, or rear end of the connector arrangement  101 . 
         [0054]    Any transverse misalignment between the first end of the connector arrangement  101  and the connector elements  105  at the second end of the arrangement  101  is accommodated by the taper in the dielectric sleeve  111 . The sleeve passage  112  has a taper angle that is continuous and that has an angle of no more than 3°. 
         [0055]    Specific embodiments of the invention have been described. However, those skilled in the are will appreciate that various changes may be made to the without departing from the scope of the invention, as defined by the claims. 
         [0056]    For example, in the connector arrangement described above, the first end is provided with a coaxial connector having a compliant socket and a threaded outer sleeve. However other connectors, such as non-threaded connectors, may alternatively be provided. 
         [0057]    Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.