Abstract:
An electrical submersible pump assembly has a number modules including a pump, a motor and a pressure equalizer. Each module has a rotatable shaft with a splined end that joins a splined end of another module, and those splined ends may differ in dimensions. A coupling that joins the shafts has a first shell has a splined bore that mates with the splined end of the first shaft. A second shell has a splined bore that mates with the splined end of the second shaft. An adopter has a first splined end in mating engagement with the splined bore of the first shell and a second splined end in mating engagement with the splined bore of the second shell. Fasteners secure the adapter to the shells. An annular seal isolates fluid communication between the first shell bore and the second shell bore.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The invention relates to devices for coupling different dimensioned shafts of submersible pump assembly modules. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    Electrical submersible pump assemblies (ESP) are commonly used to pump well fluid from oil wells. Conventionally, ESPs have been made up of a series of interconnectable modular sections including one or more pump sections with an associated fluid intake, a motor section and a seal or pressure equalizer section. Each of these sections includes an outer housing and a central rotatable drive shaft. The drive shaft has at least ones splined ends that will join a drive shaft of an adjacent module for rotation in unison. 
         [0003]    A coupling sleeve with internal splines rotationally connects the two drive shafts. The coupling sleeve is a cylindrical member with internal splines located at each end. The housings of the modules are joined usually by bolting flanges together, alternately, an internally threaded rotatable collar may be employed to secure the housings. 
         [0004]    An assembled ESP can be quite lengthy, up to and more than 100 feet. Normally, the separate modules are brought to a well site, then connected together. When two modules are joined to each other, a technician inserts a coupling sleeve over one of the shaft splined ends and axially aligns the two modules. The modules are brought toward each other, causing the splined end of the other module to stab into the coupling sleeve. The technician then secures the housings to each other. 
         [0005]    The modules of an ESP are often interchangeable with modules of different capacities. For example, a particular pump module may be operable with a variety of different motor modules, and vice-versa. The shafts and their splined ends may differ from each other, requiring a variety of couplings. One coupling used in the past for mating different configured shaft splined ends employs a sleeve insert that is pressed into one part of the bore of the coupling. The sleeve has a splined configuration in its inner diameter that differs from the integrally formed spline configuration in the oilier part of the bore. Axially extending pins between outer diameter of the sleeve and the bore fix the sleeve to the coupling for rotation. 
       SUMMARY OF THE INVENTION 
       [0006]    An electrical submersible pump assembly has a plurality of modules including a pump, a motor and a pressure equalizer. A first one of the modules has a rotatable first shaft with a splined end. A second one of the modules has a rotatable second shaft with a splined end. A first shell has a splined bore dimensioned such that it intermeshes with the splined end of the first shaft. A second shell has a splined bore dimensioned such that it intermeshes with the splined end of the second shaft. The splined bores of the first and second shells are coaxially aligned along an axis of the assembly. A torque transfer member secures the first and second shells together such that torque of the first shaft passes through the first shell to the second shell and from the second shell to the second shaft. 
         [0007]    The torque transfer member has a first splined end that intermeshes with the splined bore of the first shell. The torque transfer member has a second splined end that intermeshes with the splined bore of the second shell. The splined end of the first shaft intermeshes with an outer portion of the splined bore of the first shell. The splined end of the second shaft intermeshes with an outer portion of the splined bore of the second shell. The second splined end of the torque transfer member optionally may have different dimensions than the first splined end. 
         [0008]    In the embodiment shown, a first retaining ring inserts into mating grooves formed on a first end of the torque transfer member and in the splined bore of the first shell. A second retaining ring inserts into mating grooves formed on a second end of the torque transfer member and in the splined bore of the second shell. An annular seal seals between the first splined end of the torque transfer member and the splined bore of the first shell. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the features, advantages and objects of the disclosure, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the disclosure briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, mat the drawings illustrate only a preferred embodiment of the disclosure and is therefore not to be considered limiting of its scope as the disclosure may admit to other equally effective embodiments. 
           [0010]      FIG. 1  is a schematic side view of a pump assembly constructed in accordance with this invention. 
           [0011]      FIG. 2  is an enlarged sectional view of a coupling for coupling together shafts from two of the modules of the pump assembly of  FIG. 1  and taken along the line  2 - 2  of  FIG. 3 . 
           [0012]      FIG. 3  is a sectional view of the coupling of  FIG. 2 , taken along the line  3 - 3  of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The methods and systems of the present disclosure will now he described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The methods and systems of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
         [0014]    It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
         [0015]    Referring to  FIG. 1 , a well  11  has casing  13  that is perforated or has other openings to admit well fluid. A pump assembly  15  is suspended in well  11  to pump well fluid from well  11 . Although shown installed vertically, pump assembly  15  could be located within on inclined or horizontal section of well  11 , or it could be mourned exterior of well  11  for boosting the pressure of well fluid flowing from the well. 
         [0016]    Pump assembly  15  includes a motor  17 , normally a three-phase electrical motor. A seal section or pressure equalizer  19  connects to motor  17  if pump assembly  15  is submersed. Seal section  19  has components, such as a bladder or bellows, for reducing a pressure differential between dielectric lubricant contained in motor  17  and the hydrostatic pressure of the well fluid in well  11  surrounding motor  17 . Although shown above motor  17 , seal section  19  could be mounted to a lower end of motor  17 . 
         [0017]    A pump  21  connects to the opposite end of seal section  17 . Pump  21  may be a centrifugal pump with numerous stages, each stage having an impeller and a diffuser. Alternately, pump  21  may be a progressing cavity pump, having a helical rotor that rotates within an elastomeric stator. Pump  21  could also be a reciprocating type. Pump  21  has an intake  23  for drawing in well fluid. A gas separator (not shown) may be mounted between motor  17  and pump  21 , and if so, intake  23  would be located in the gas separator. A string of production tubing  25  suspends pump assembly  15  in casing  13  in most installations. 
         [0018]    Motor  17 , seal section  19 , and pump  21  are in separate modules brought to the well site, then secured together. Pump assembly  15  could have other modules, including a gas separator or additional pumps and motors connected in tandem. The various modules are connected either with bolted flanges or with rotatable threaded collars. 
         [0019]    Referring to  FIG. 2 , a first shaft  27  is rotatably mounted in a first one of the modules, such as motor  17 . First shaft  27  has a splined end  29  with an outer diameter  31 , measured at the crests of the splines. A second shaft  33  is rotatably mounted in a second one of the modules, such as seal section  19 . Second shaft  33  also has a spline end  35 . Since the modules of pump assembly  15  are interchangeable, for various reasons, sometimes the dimensions of splined end  29  will differ from splined end  25 . For example, the outer diameter  37  of splined end  35  of shaft  33  optionally may be smaller than outer diameter  31  of splined end  29  of first shaft  27  or vice-versa. The difference may not always be a large amount; for example, the difference in diameter may only be about 1/16 inch, thus is not visible in  FIG. 2 . Alternately, the outer diameters  31 ,  37  of shafts splined ends  29 ,  35  could be the same, but other differences exists. Much as the number of or the configurations of the splines within each splined end  29  and  35 . 
         [0020]    A coupling  39  for coupling splined ends  29  and  35  for rotation together accommodates the dimensional differences between splined ends  29  and  15 . Shafts  27  and  33  are illustrated as being spaced from coupling  39 , but once assembled, with be located within coupling  39 . Coupling  39  is formed in two parts that are secured together to accommodate a variety of different dimensions. Coupling  39  has a first shell  41  that is cylindrical member having a bore  43  with splines  45  extending partway along the length of bore  43 . Splines  45  and bore  43  are dimensioned to match the configuration of first shaft splined end  29  so as to receive and intermesh with first shall splined end  29 . 
         [0021]    Coupling  39  has a second shell  47  that is a cylindrical member having a bore  49  with splines  51  extending partway along the length of bore  49 . Splines  51  and bore  49  are dimensioned to match the configuration of second shaft splined end  35  so as to receive and intermesh with second shaft splined end  35 . 
         [0022]    The sectional view of  FIG. 2  cuts through portions of splines  45 , rather than the valleys between the splines as can be seen by the sectional line in  FIG. 3 . In the example shown, second shell splines  51  do not axially align with first shell splines  45 . That is, an axially extending line along the crest of one of the splines  51  does not pass along a crest of one of the splines  45 . 
         [0023]    First shell  41  has an outer end  53  into which first shaft  27  stabs. First shell  41  has an inner end  55 , and first shell bore  43  extends completely from outer end  53  to inner end  55 . Second shell  47  has an outer end  57  into which second shaft  33  stabs. Second shell  47  has an inner end  59 , and second shell bore  49  extends completely front outer end  57  to inner end  59 . When coupling  39  is assembled, first shell inner end  55  will preferably be in abutment with second shell inner end  59 , but a slight clearance could exist. First shell bore  43  will be coaxial with second shell bore  49  along an axis  61  of pump assembly  15  ( FIG. 1 ). 
         [0024]    First shell  41  has a counterbore  63  that begins at inner end  55  and extends a selected distance toward first shell outer end  53 . Counterbore  63  defines a shoulder  65  axially spaced from inner end  55  and facing inner end  55 . Splines  45  extend from first shell outer end  53  to shoulder  65 . The length of splines  45  is preferably greater than the axial length of counterbore  63 . 
         [0025]    Second shell  47  has a counterbore  67  that begins at inner end  59  and extends a selected distance toward second shell outer end  57 . Counterbore  67  defines a shoulder  69  axially spaced from inner end  59  and facing inner end  59 . Splines  51  extend from second shell outer end  57  to shoulder  69 . The length of splines  51  is preferably greater than the axial length of counterbore  67 . The length of second shell splines  51  may be the same as the length of first shell splines  45 . First and second shells  41 ,  47  are preferably symmetrical about axis  61 . 
         [0026]    A torque transfer member or adapter  71  connects first shell  41  to second shell  47  for rotation in unison, and also axially fixes shells  41  and  47  together. In this example, adapter  71  locates within first shell bore  43  and second shell bore  49 . Adapter  71  has a first end  73  with external splines  75  ( FIG. 3 ) that are dimensioned for intermeshing engagement with the splines of splined end  29  of first shaft  27 . Adapter first end splines  75  have a length selected to place them in engagement with part of the length of splines  45 . Preferably, the length of adapter first end splines  75  is less than one-half a length of splines  45 . 
         [0027]    Adapter  71  has a second end  77  with external splines  78  that are dimensioned for intermeshing engagement with the splines of splined end  35  of second shaft  33 . Adapter second end splines  77  have a length selected to place them in engagement with part of the length of splines  51 . Preferably, the length of adapter second end splines  78  is less than one-half a length of splines  51 . Adapter second end splines  78  will normally differ from adapter first end splines  75 . The difference could be in the outer diameters of second end splines  78  and first end splines  75 . The difference could also be in the configuration and number of second end splines  78  as compared to first end splines  73 . 
         [0028]    Adapter  71  has a central portion  79  between first end  73  and second end  77  that is free of splines. Central portion  79  extends through counterbores  63  and  67  approximately from the inner end of first end splines  75  to the inner end of second end splines  78 . Central portion  79  has a cylindrical outer surface that may base an outer diameter slightly different from or the same as the outer diameter of adapter first end  73  and adapter second cod  77 . Adapter  71  is preferably symmetrical about its longitudinal axis, which coincides with axis  61 . What appears to be asymmetrical differences in  FIG. 2  on the left and right sides of adapter  71 , as shown, are not differences; rather what appears to be different is actually due to the sectional plane of  FIG. 2 . 
         [0029]    Adapter  71  may be secured to first and second shells  41 ,  47  in different manners. In this example, adapter  71  is secured to first shell  41  by a first retaining ring  81  that extends around adapter central portion  79 . First retaining ring  81  has an inner diameter that locates within a groove on the outer surface of adapter central portion  79  and an outer diameter that locates within a groove in the inner diameter of counterbore  63 . First retaining ring  81  is a resilient, biased, metal split or snap ring in this embodiment. First retaining ring  81  axially fixes first shell  41  to adapter first end  73 . The engagement of adapter first end splines  75  with first shell spines  45  rotationally secures adapter  71  to first shell  41 . 
         [0030]    In this example, adapter  71  is secured to second shell  47  by a second retaining ring  83  that extends around adapter central portion  79 . Second retaining ring  83  has an inner diameter that locates within a groove on the outer surface of adapter central portion  79  and an outer diameter that locates within a groove in the inner diameter of counterbore  67 . Second retaining ring  83  is a resilient, metal, biased, split or snap ring in this embodiment. Second retaining ring  81  axially fixes second shell  47  to adapter second end  77 . The engagement of adapter second end splines  78  with second shell splines  51  rotationally secures adapter  71  to second shell  47 . 
         [0031]    Preferably when both retaining rings  81 ,  83  are installed, first shell inner end  55  is in abutment or close to contact with second shell inner end  59 . Alternates ways to secure adapter  71  to first and second shells  41 ,  47  include threads or pins. 
         [0032]    A seal ring  85  may be installed between adapter central portion  79  and one of the counter bores  63 ,  67 . In this example, seal ring  85  is located in a groove in first shell counterbore  63  and sealingly engages adapter central portion  79 . Seal ring  85  may be elastomeric. 
         [0033]    When assembling pump assembly  15 , a coupling will be needed for connecting the shaft of each module of pump assembly  15  to the shaft of an adjacent module. Some of the modules to be joined may have identical shaft splined ends; if so conventional couplings of a unitary integral design may be employed. If some do not match, a technician will assemble a coupling  39  with first and second shells  41  and  47  to join the shafts  27 ,  33  that are to be coupled together. Normally, the technician will have a supply of first and second shells  41 ,  47  kept unattached and having different dimensions for splines  45 ,  51 . The technician will also have a supply of adapters  71  with a variety of dimensions for first and second ends  73 ,  77 . Once the proper shells  41 ,  47  and adapter  71  have been located to match the particular shaft splined ends  29 ,  35 , the technician will assemble coupling  39  using retaining rings  81 ,  83 . 
         [0034]    At the well site, the technician will axially align a first shaft  27  of one of the modules with a second shaft  33  of another module. The technician will insert first shell bore  43  over first shaft  27 . First shaft spline end  29  will mate with first shell splines  45  and extend into bore  43  to a point axially spaced from adapter first end  73 . Normally, first shaft splined end  29  will engage a greater length of splines  45  than the length engaged by adapter first end  73 . The technician will then insert second shaft splined end  35  into second shell bore  49 . Second shaft splined end  35  will mate with second shell splines  51  and extend into bore  49  to a point axially spaced from adapter second end  77 . Normally, second shaft splined end  35  will engage a greater length of splines  51  than the length engaged by adapter second end  77 . The technician will secure the housings of the two modules together using bolted flanges or a threaded collar. 
         [0035]    While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes.