Abstract:
Pump apparatus, systems and methods of making and using same are disclosed. One inventive system includes a coupling member, a first shaft and a second shaft, the coupling member connecting the first shaft with the second shaft, the coupling member defining a first axial chamber accepting the first shaft, and a second axial chamber accepting the second shaft, the chambers separated by a coupling plate, the chambers including torsional motion transmitting elements and axial motion securing elements in the first and second axial chambers for axially securing the shafts in the coupling member. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72( b ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates generally to the field of fluid transfer, and more specifically to submersible and surface pump apparatus and systems and methods of making and using same. 
   2. Related Art 
   Vertical and horizontal centrifugal pump systems are designed to operate in downthrust mode, where pressure inside the pump case by action of the pump impellers tends to exert an axial force on the pump shaft toward the suction inlet. Most pump and motor manufacturers instruct users not to operate these pumps in upthrust mode, where pressure exerted by pumped fluid against the impellers at the suction inlet may result in damaged impellers, a damaged pump shaft, and damaged pumps seals and bearings. Upthrust conditions may exist at startup, when operating at high flow rates, and/or when the specific gravity of the fluid being pumped changes. In the upthrust condition, bearings may not be cooled sufficiently due to lack of recirculation and may fail. Some pump manufacturers use a disk-type upthrust pad at the discharge/exit area of the pump to limit the upthrust movement of the shaft. Other pump manufactures have used combinations of a grooved upthrust pad in the diffuser and grooved radial bore in the diffuser to prevent the loss of lubrication to the bearing in the upthrust condition. These approaches are not always successful. 
   It is evident that there is a need in the art for pump apparatus and methods which more adequately address the upthrust condition problem. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, coupling members, systems including same, and methods of making and using same are described that reduce or overcome problems in previously known apparatus and methods. Apparatus of the invention comprise a securing mechanism to limit upthrust, or limit the tendency of a pump shaft going into the upthrust condition, and therefore reduce or prevent failure. In systems of the invention one shaft, such as a pump shaft, is secured axially and rotationally to the coupling, and the coupling is in turn secured axially and rotationally to a second shaft, such as a thrust chamber shaft. 
   A first aspect of the invention is coupling members adapted to connect a first shaft, such as a pump shaft, with a second shaft, such as a thrust chamber shaft. The coupling members of the invention are adapted to connect a first shaft with a second shaft, the coupling member comprising means for transmitting rotational movement between the shafts and means for securing the shafts from substantial axial movement during rotation of the shafts and coupling member, the coupling member including at least one torque-limiting element. The first shaft may be a pump shaft while the second shaft may be a thrust chamber shaft, although the invention is not so limited. Any means for securing the first and second shafts to the coupling member may be used, including any combination of male/female connections, as long as the transmission of rotational motion and axial securing functions are achieved. For example, coupling member may have dual female receptacles for accepting ends of the shafts; one side of the coupling member may have a female receptacle while the other has a male portion connecting to a female portion of the other shaft, and so on. In certain embodiments, the coupling member defines a first axial chamber adapted to accept a first end of the first shaft, and a second axial chamber adapted to accept a first end of the second shaft, the axial chambers separated by a coupling plate, which in some embodiments has a through hole adapted to accept a male portion of an axial motion securing member, and in other embodiments is a solid plate. The means for transmitting rotational movement may be selected from splines, pins, bolts, rivets, clamps, rings, threads, grooves, gears, bearings, collets, or other equivalent functional elements. The coupling members may also include axial motion securing elements in the first and second axial chambers for axially securing the shafts in the coupling member. 
   For convenience only, the first shaft is hereinafter referred to as the pump shaft, and the second shaft is referred to as a thrust chamber shaft, however, those of skill in the art will recognize that the inventive coupling members, systems, and methods may be used when coupling any two rotating shafts. 
   The inventive coupling members may be used in systems of the invention, which comprise a second aspect of the invention. Systems of the invention comprise a coupling member connecting a first shaft with a second shaft, the coupling member comprising means for transmitting rotational movement between the shafts and means for securing the shafts from substantial axial movement during rotation of the shafts and coupling member, the coupling member including at least one torque-limiting element. In certain embodiments, the first end of the pump shaft, or a sub-shaft or component intermediate of the pump shaft first end is axially secured in the inventive coupling member. One way of accomplishing this is by virtue of a female aperture or receptacle extending inwardly from the pump shaft first end a certain distance and accepting a male portion of a pump shaft axial securing member, the female receptacle and the male portion of the pump shaft axial securing member being threaded in matching relationship. The pump shaft axial securing member may have a head, forming with the male portion a bolt. In these embodiments the male portion protrudes through a central through hole in a coupling plate and threadingly engages the threads in the female receptacle, while the head engages the coupling plate, thus axially securing the pump shaft to the coupling member upon tension forces, in other words, forces tending to move the pump shaft axially away from the coupling plate, such as during upthrust conditions. 
   Alternatively, systems of the invention include those wherein the female receptacle in the pump shaft first end may comprise one or more grooves, such as J grooves, while the male portion of the pump shaft adjusting member includes one or more radially extending pins or other protuberances, the pins sliding into matching respective grooves and engaging a portion of the groove to axially secure the pump shaft. Other shaped grooves may of course be used, as long as the securing function is achieved. In certain system embodiments the pump shaft may be axially secured to the coupling member by one or more pins inserted through matching transverse passages through walls of the coupling member which define the first chamber and through a corresponding transverse passage in the pump shaft. The pin or pins may be tapered, threaded their whole or a portion of their length, or held by cotter pins. The pins may comprise any shape and material sufficient to provide the axial securing function, that is, of retaining the axial position of the pump shaft and coupling member so that the pump and motor thrust bearings are not damaged by upthrust or other conditions. Alternatively, to avoid forming a passage through the pump shaft, the pump shaft may be modified on its outer surface proximate the first chamber inner wall to be threaded or accept a threaded collar which also has threads on its outer surface and mating with threads on the inner wall of the first chamber. A two-piece ring, a snap ring, or combination thereof, or other axial securing retainer, as described further herein, may be employed. Alternative embodiments include those wherein the pump shaft first end comprises a female receptacle, while the coupling member comprises a male member. Any of the mentioned securing means may be used in these embodiments. 
   In certain system embodiments the pump shaft axial securing member is adjustable, such as when the male portion is threaded and meshes with a threaded receptacle in the pump shaft or intermediate component, or when the pump shaft end is threaded or a threaded collar is used. This has certain advantages as will be discussed herein. In addition, one or more pump shaft shims may be positioned between the coupling plate and the first end of the pump shaft, the male portion of the pump shaft axial securing member passing through the shims and through the coupling plate. The pump shaft shims, if used, may comprise a material that is the same as or different from the coupling member material and the pump shaft. In certain embodiments the pump shaft, pump shaft shims, and coupling member are all of the same material. The pump shaft axial securing member head may include surfaces allowing the head to be turned by a tool, such as a wrench, screw driver or other tool. The pump shaft axial securing member head may or may not be the same material as the male portion. 
   Systems of the invention include those wherein the thrust chamber shaft is axially secured in the second chamber. In certain embodiments the thrust chamber shaft is axially secured to the coupling member by a two-piece ring and snap ring. Alternatively, one or more pins may be inserted through matching transverse passages through walls of the coupling member which define the second chamber and through a passage in the thrust chamber shaft. The pin or pins may be tapered, threaded, or held by cotter pins. The pins may be comprised of any shape and material sufficient to provide the axial securing function, that is, of axially securing the relative position of the thrust chamber shaft and coupling member so that the pump and motor thrust bearings are not damaged by upthrust or other conditions. Alternatively, to avoid forming a passage through the thrust chamber shaft, the thrust chamber shaft may be modified on its outer surface proximate the second chamber inner wall to be threaded or accept a threaded collar which also has threads on its outer surface and mating with threads on the inner wall of the second chamber. Alternative embodiments include those wherein the thrust chamber shaft first end comprises a female receptacle, while the coupling member comprises a male member. Any of the mentioned securing means may be used in these embodiments. 
   In embodiments employing a coupling plate, the coupling plate may be positioned anywhere internally of the coupling member as long as it separates the two chambers and serves the pump shaft axially securing function in conjunction with the pump shaft axial securing member. The coupling plate may be integral to the coupling member body or a separate piece inserted into the coupling member body. Further, the coupling plate is only required when using a bolt to secure the coupling member to one of the shafts. Apparatus and systems of the invention include those wherein the coupling member is cylindrical in shape, as are the first and second axial chambers. However, neither the axial chambers nor the portions of the shafts which fit therein are required to be cylindrical in shape. In fact, square shafts, hex shafts or any other of a number of configurations could be employed for engaging the chambers or shafts together. The coupling member and coupling plate (if present) may be all one and the same material, but this is not required. Combinations of different materials may be used as desired. The coupling plate may have two substantially parallel surfaces substantially perpendicular to the longitudinal axis of the pump shaft and thrust chamber shaft. In these embodiments the pump shaft axial securing member interacts with the coupling plate by way of a head that abuts against a surface of the coupling plate that faces the thrust chamber shaft. In other embodiments, the side of the coupling plate facing the thrust chamber shaft may have a recessed area that accepts the head of the pump shaft axial securing member so that it abuts the recessed area, allowing the first end of the thrust chamber shaft to be positioned substantially flush against the coupling plate. In certain embodiments the coupling plate is positioned approximately midway between the ends of the coupling member. Apparatus and systems of the invention include those wherein the first and second axial chambers of the coupling member have equal diameters, apparatus and systems wherein the chambers have different diameters, and apparatus and systems wherein one or both axial chambers have truncated conical shape. 
   Apparatus and systems of the invention include a torque-limiting feature functioning to physically break the coupling member upon exposure to excessive torque conditions. One such feature is a portion of the coupling member having a reduced thickness cross section, as described more fully herein. The reduced thickness cross section or sections may be positioned anywhere, but in certain embodiments it may be advantageous to place one reduced thickness portion approximately at the axial midpoint of the coupling member, or between the coupling plate (if present) and one of the ends of the coupling member, either on the thrust shaft side or the pump shaft side of the coupling member. Two or more reduced thickness portions may be envisioned in certain other embodiments. The reduce thickness cross sections may be annular grooves or depressions of any shape. Alternatively, or in conjunction with reduced thickness cross sections, apparatus and systems of the invention may include one or more radially and/or longitudinally extending shear pins. Another alternative is the use of spring-load mechanisms, such as spring-load ball and groove features. 
   Another aspect of the invention are methods of making a locked pair of shafts, one method of the invention comprising: 
   (a) measuring axial shaft movement of first and second shafts during operation using a standard coupling; 
   (b) selecting a coupling member to limit the axial shaft movement; and 
   (c) installing the coupling member to limit the axial shaft movement. 
   Methods of the invention include those wherein the selecting a coupling member to limit shaft movement includes calculating the width and/or number of shaft shims required to limit the axial shaft movement, and installing one or more shaft shims in the coupling by bolting or other means. In one embodiment, the first shaft is a pump shaft that is axially secured using a bolt and optional shaft shims, while the second shaft is a thrust chamber shaft that is secured axially to the coupling using one or more pins, bolts, or other means. In horizontal and other pumping systems, the pin (or bolt or screw) may be inserted through the intake of the pump. 
   Yet another aspect of the invention are methods of pumping fluids, one method comprising: 
   (a) determining a pumping requirement for transferring a fluid; 
   (b) selecting a pump having a pump shaft, and a driver having a driver shaft; 
   (c) coupling the pump shaft and driver shaft axially using a coupling member of the invention; and 
   (d) pumping the fluid using the pump to meet the pumping requirement. 
   Apparatus and systems of the invention may be used down-home pumping systems, in submersible pump systems, and in horizontal pumping systems, and may be used between any two shafts in such systems, such as shafts between a driver and a pump, between two pump sections, between a pump and an auxiliary device such as an auger or other fluid transmission device. In pumping systems including motors, especially downhole pumping systems, the systems may include a motor protector, which may or may not be integral with the motor, and may include integral instrumentation adapted to measure one or more downhole parameters. Pump systems employing apparatus and systems of the invention may be adapted to produce a dynamic head up to 7,500 feet or more. The driver shaft may be one and the same as the pump shaft in certain embodiments, and in certain other embodiments the pump shaft may be mechanically coupled to and driven by the driver shaft. In other embodiments, the driver shaft and the pump shaft may be distinct and not be coupled mechanically, such as in magnetic couplings wherein the driver shaft drives a magnetic coupling comprising magnets on the driver shaft which interact with magnets in a protector, in which case the protector shaft mechanically connects to and drives the pump shaft. 
   Apparatus and methods of the invention will become more apparent upon review of the brief description of the drawings, the detailed description of the invention, and the claims that follow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The manner in which the objectives of the invention and other desirable characteristics can be obtained is explained in the following description and attached drawings in which: 
       FIGS. 1-3  illustrate schematically in side-elevation, partial cross-sectional views of a prior art horizontal pumping system, and certain problems therewith; and 
       FIGS. 4-19  illustrate schematically in side elevation, partial cross-sectional views, of non-limiting embodiments of apparatus, systems, and methods of the invention. 
   

   It is to be noted, however, that the appended drawings are not to scale and illustrate only typical embodiments of this invention, and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
   DETAILED DESCRIPTION 
   In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
   All phrases, derivations, collocations and multiword expressions used herein, in particular in the claims that follow, are expressly not limited to nouns and verbs. It is apparent that meanings are not just expressed by nouns and verbs or single words. Languages use a variety of ways to express content. The existence of inventive concepts and the ways in which these are expressed varies in language-cultures. For example, many lexicalized compounds in Germanic languages are often expressed as adjective-noun combinations, noun-preposition-noun combinations or derivations in Romanic languages. The possibility to include phrases, derivations and collocations in the claims is essential for high-quality patents, making it possible to reduce expressions to their conceptual content, and all possible conceptual combinations of words that are compatible with such content (either within a language or across languages) are intended to be included in the used phrases. 
   The invention describes coupling members, systems incorporating same, and methods of making and using same for pumping fluids, for example, to and from wellbores, although the invention is applicable to pumps designed for any intended use, including, but not limited to, so-called surface fluid transfer operations. A “wellbore” may be any type of well, including, but not limited to, a producing well, a non-producing well, an experimental well, and exploratory well, and the like. Wellbores may be vertical, horizontal, some angle between vertical and horizontal, and combinations thereof, for example a vertical well with a non-vertical component. As discussed, vertical and horizontal centrifugal pump systems are designed to operate in downthrust mode, where pressure inside the pump case by action of the pump impellers tends to exert an axial force on the pump shaft toward the suction inlet. Most pump and motor manufacturers instruct users not to operate these pumps in upthrust mode, where pressure exerted by pumped fluid against the impellers at the suction inlet may result in damaged impellers, damage the pump shaft, and damaged pumps seals and bearings. Upthrust conditions may exist at startup, when operating at high flow rates, and/or when the specific gravity of the fluid being pumped changes. In the upthrust condition, bearings may not be cooled sufficiently due to lack of recirculation and may fail. Previous approaches to solving these problems are not always successful. 
   Given that there is considerable investment in existing equipment, it would be an advance in the art if upthrust conditions and their consequences could be avoided or reduced, and further if a torque-limiting feature could be included, so that more expensive components, such as shafts, do not fail before less expensive components, such as couplings. This invention offers methods and apparatus for these purposes. A torque-limiting element is placed in the coupling members of the invention for the purpose of having the coupling “fail” at a specified torque value generally less than the value needed to “fail” either of the shafts. “Failure”, as used herein, means limiting the ability of the coupling to transmit torque between the two shafts. This can be accomplished in any number of ways including appropriate choice of a coupling material(s), employing the use of one or more grooves on the OD or ID of the coupling having a variable length and depth so as to limit the cross sectional area and thus the strength of the coupling to a predetermined value. The depth of the grooves may be equal to zero depending on the design and/or choice of material. Use of one or more radial or longitudinal “shear” pins may provide the torque-limiting feature. Another means for torque limiting employs the use of a press fit member designed to slip under a given torsional load. Spring loaded mechanisms and cam loaded mechanisms may be used. Any combination of these means may be employed in a given situation. 
     FIGS. 1-3  illustrate schematic side-elevation, partial cross-sectional views of a prior art horizontal pumping system  100 , useful for illustrating certain problems therewith.  FIG. 1  illustrates a motor  2 , horizontal pump  4  having a pump inlet  6  and a pump outlet  8 , and a thrust chamber  10 . Motor  2  is supported on a surface  18  by a motor support  12 , and pump  4  is supported by pump supports  14  and  16 . Surface  18  may be earthen, concrete, metal, or virtually any structural support member. Thrust chamber  10  has thrust bearings (not illustrated) for carrying the downthrust, indicated by arrow DT in  FIGS. 1 and 2  produced by pump impellers  24 . As more clearly illustrated in  FIGS. 2 and 3 , thrust chamber  10  connects a thrust chamber shaft  20  to a pump shaft  22  through a coupling  26  to transmit torque and rotation speed using splines  28  and  30 . Shaft shims  32  are used for preventing the downward movement of the shaft so that all the down thrust produced by pumping action is transferred to the thrust bearings in the thrust chamber. Pump shaft  22  is free to move horizontally to the right in  FIGS. 1-3  (or in the axial direction) allowing the stages to go in the upthrust, indicated by large arrow UT and small arrows  34  ( FIG. 3 ). 
     FIGS. 4-19  illustrate schematic side-elevation, partial cross-sectional views, not necessarily to scale, of apparatus, systems, and methods of the invention only as examples, but the invention is not so limited, and are presented only for explaining some of the inventive concepts.  FIG. 4  illustrates system embodiment  200  of the invention. Coupling member  35  has a first axial chamber in which a first end of pump shaft  22  is fitted with spline connections  30 , and a second axial chamber into which thrust chamber shaft  20  is fitted with spline connections  28 , as in previously known coupling members. However, in addition coupling member  35  has a threaded female aperture  38  extending from the end of the pump shaft inwardly a certain distance, determined by the particular tension loads expected, the materials of construction, and the like. Coupling member  35  includes in embodiment  200  a coupling plate  37  having a central through hole  40 . Threaded male member  36  threadingly fits with mating threads of threaded female aperture  38 . Male member  36  includes a head  42  which engages a transverse surface of coupling plate  37  inside of a recessed portion  43  of thrust shaft  20 . Coupling member  35  also includes in embodiment  200  a pair of transverse through holes  45  and  47  in the wall forming the second axial chamber of coupling member  35  through which a pin  49  is tightly fitted. A similar size through hole  51  in thrust chamber shaft  20  at a matching location accepts pin  49 . The arrangement of through holes  45 ,  47 , and  51  with pin  49  serves the functions of transferring torque from thrust chamber  20  to coupling member  35  and axial tension forces. A torque-limiting feature  46  may be included, in this embodiment a groove or thin region of the wall of coupling member  35 . Torque-limit feature  46 , if present, functions as a failure mechanism, so that coupling member  35  may fail, rather than more expensive components, such as shafts  20 ,  22 . 
   In use, pump shaft  22  movement in upthrust and downthrust conditions may be measured. Shaft shims  44  having a central through hole through which shaft  36  threadedly fits may be employed as desired. Based on the measured or observed axial movement of pump shaft  22 , the length (or number) of shaft shims  44  required is calculated so that pump shaft  22  has limited movement. During installation, the required number of shaft shims  44  and pump shaft  22  are bolted to coupling member  35  with bolt  26 ,  42 . The pump is then installed, for example in a horizontal skid. Pump shaft  22  is rotated so that the radial hole  45  in coupling member  35  and though hole  51  in thrust chamber shaft  20  match. Pin  49 , which may also be a bolt, or screw, is used to secure coupling member  35  with thrust chamber shaft  20 . The securing device may be installed through pump intake  6 . 
   In certain embodiments of the invention, a variety of seals, filters, absorbent assemblies and other protection elements may be used to protect motors and other components, particularly if the apparatus and systems of the invention are to used in downhole applications. These components are not illustrated for clarity, but may include, for example, one or more thrust bearings disposed about shafts  20  and  22  to accommodate and support the thrust load from pump  4 . A plurality of shaft seals may also disposed about shaft  20  between pump  4  and motor  2  to isolate a motor fluid in motor  2  from external fluids, such as well fluids and particulates. Shaft seals also may include stationary and rotational components, which may be disposed about the shafts in a variety of configurations. Systems of the invention also may include a plurality of moisture absorbent assemblies disposed throughout housings between a pumps and a motor. These moisture absorbent assemblies absorb and isolate undesirable fluids (for example, water, H2S, and the like) that have entered or may enter housing through shaft seals or though other locations. For example, moisture absorbent assemblies may be disposed about shaft  20  at a location between pump  4  and motor  2 . In addition, the actual protector section above the motor may include a hard bearing head with shedder. 
     FIG. 5  illustrates another apparatus and system embodiment  300  of the invention. Coupling member  35  is similar to embodiment  200  depicted in  FIG. 4 , with slight differences. Pump shaft  22  is once again held in coupling member  35  via a bolt  36 ,  42 , however in embodiment  300  bolt head  42  is set in a recessed area  45  of coupling plate  37 . This allows thrust chamber shaft  20  to be flush at its end up against coupling plate  37 . Another difference is that thrust chamber shaft  20  is secured axially by use of a two piece ring  48  and a snap ring  50 . Two piece ring  48  is held by a groove  53  in thrust chamber shaft  20 . 
   Another apparatus and system embodiment  400  is illustrated schematically in  FIG. 6 . Comparing to embodiment  300  of  FIG. 5 , note that embodiment  400  does not include a threaded bolt to axially secure pump shaft  22  to coupling member  35 , but rather has a threaded collar  52 , having internal threads  54  mating with similar threads on pump shaft  22 , and external threads  56  matching corresponding threads on the inside wall of the first axial chamber of coupling member  35 . 
     FIG. 7  illustrates apparatus and system embodiment  500  of the invention. The coupling of thrust chamber shaft  20  to coupling member  35  in embodiment  500  is exactly the same as in embodiments  300  and  400 , however the coupling of pump shaft  20  to coupling member  35  makes use of two pins, bolts, or screws  58  and  60 , which extend through the wall of coupling member  35  an pump shaft  20  in through holes. One pin or more than two pins may be employed as needed, depending on the particular torque requirements materials of construction, environmental conditions, and degree of safety margin desired or required by local laws, and the like. 
     FIG. 8  illustrates yet another apparatus and system embodiment  600 , wherein both the pump shaft  22  and thrust chamber shaft  20  are axially secured using two piece rings and snap rings. Thrust chamber shaft  20  is secured axially by use of two piece ring  48  and snap ring  50 . Two piece ring  48  is held by a groove  53  in thrust chamber shaft  20 . In like manner pump shaft  22  is secured axially by use of a two piece ring  48 ′ and a snap ring  50 ′. Two piece ring  48 ′ is held in a groove  53 ′ in thrust chamber shaft  20 . 
     FIGS. 9 and 10  illustrate apparatus and system embodiments  700  and  800 , respectively, wherein each embodiment uses the same axial securing features for pump shaft  22  as embodiment  300  of  FIG. 5 . In embodiment  700  of  FIG. 9 , thrust chamber shaft  20  is axially secured to coupling member  35  using a threaded collar  64  having internal threads  68  matching corresponding threads in thrust chamber shaft  20 , and external threads  66  matching corresponding threads in coupling member  35 . In embodiment  800  of  FIG. 10 , thrust chamber shaft  20  is axially secured in coupling member  35  using a tapered pin  70 , having a smaller diameter end  72 . Pin  70  is tightly fit inside through holes  71  and  73  in coupling member  35  wall, and through hole  75  in thrust chamber shaft  20 . More than one pin  70  may be employed, with corresponding through holes. 
     FIG. 11  illustrates another apparatus and system embodiment  900  of the invention, which may be explained as a mirror image of embodiment  300  of  FIG. 5 . Thrust chamber shaft  20  is axially secured in coupling member  35  via a bolt  36 ′,  42 ′, and bolt head  42 ′ is set in a recessed area  45 ′ of coupling plate  37 . This allows pump shaft  20  to be flush at its end up against coupling plate  37 . Pump shaft  22  is secured axially by use of a two piece ring  48 ′ and a snap ring  50 ′. Two piece ring  48 ′ is held in a groove  53 ′ in pump shaft  20 . 
     FIG. 12  illustrates another apparatus and system embodiment  1000  of the invention, identical in all aspects to embodiment  300  of  FIG. 5  except for the torque-limit feature. Rather than a groove or thinned wall region  46  as in embodiment  300  of  FIG. 5 , embodiment  1000  of  FIG. 12  includes a pair of longitudinal shear pins  74  and  76  (one pin or more than two pins may be used). Other torque-limit features, such as radially placed shear pins, radially or longitudinally placed spring-loaded mechanisms, and the like, may be used, and are considered viable options for use in apparatus, systems and methods of the invention. 
     FIGS. 13-19  illustrate yet other embodiments of the invention.  FIG. 13A  illustrates the assembled apparatus embodiment  1100 , and  FIG. 13B  illustrates a partially exploded view. Embodiment  1100  includes a thrust chamber shaft  20  and pump shaft  22  secured in a coupling member  35 . Splines  28  and  30  are used in spline connections in embodiment  1100  to provide torque transmission. Splines  28  in this embodiment are extended at  31  ( FIG. 13B ) so that they are longer than coupling member  35 . External snap rings  81  and  82  are employed for axially securing the shafts. Groove  77  is provided in shaft  20  ( FIG. 13D ) for external snap ring  81 , while a similar groove is provided in shaft  22  for external snap ring  82 .  FIG. 13B  also depicts shims  44 , which are optional. Shims  44  have a central through hole  29  ( FIG. 13C ) so that if used they will accept a threaded bolt  80 , which is installed in mating threads  79  in shaft  20 . An unthreaded lead-in  78  is provided to promote assembly of this embodiment. A torque-limit feature may be provided by any of the means discussed herein; in embodiment  1100 , this feature would be provided by the materials of construction of coupling member  35 . 
     FIGS. 14A-14D  illustrate another embodiment  1200  of the invention.  FIG. 14A  illustrates the assembled apparatus embodiment  1200 , and  FIG. 14D  illustrates a partially exploded view without the coupling member. In embodiment  1200 , spline connections  28 ,  28 ′, and  30  are once again employed for torque transmission. Securing shaft  20  axially is accomplished by way of a pin (not illustrated) fitting in a through hole  86  in coupling member  35  ( FIGS. 14B and 14C ), and a mating cut out  87  in shaft  20 . Note that cut out  87  is not a through hole in shaft  20 ; this may provide more strength for shaft  20 . Axially securing shaft  22  is accomplished by use of an internal snap ring  50 ′, an external snap ring  83 , and two piece ring  48 , the latter fitting in a channel in shaft  22  ( FIG. 14D ). Internal snap ring  50 ′ fits in a groove  85  in coupling member  35  ( FIG. 14B ). A torque-limit feature may be provided by any of the means discussed herein; in embodiment  1200 , this feature could be provided by the materials of construction of coupling member  35 , as well as the through hole  86 . 
     FIGS. 15A-15D  illustrate another embodiment  1300  of the invention. Spline connections  28 ,  30  are employed for torque transmission. Embodiment  35  does not include a separate coupling member  35 . Rather, coupling of shafts  20  and  22  is through a male/female connection.  FIG. 15A  is an exploded view of embodiment  1300 , illustrating an external chamfered end  89  of shaft  20  fitting into an internal chamfered end  90  of shaft  22 . A groove  77  in shaft  20  is adapted to hold a wire snap ring  88 , which may be a round wire snap ring. Snap ring  88  is designed to snap into an internal channel  91  in shaft  22  during installation, axially securing shaft  20  to shaft  22 . Spline couplings  28 ,  30 , snap ring  88  and groove  91 , and the female end of shaft  22  essentially make up a coupling member. IN this embodiment, shaft  22  is a hollow shaft, as indicated  23 , although the invention is not so limited. As depicted sequentially in  FIGS. 15B ,  15 C, and  15 D, as shaft  20  slides into the female opening in the end of shaft  22 , snap ring  88  is first compressed by chamfer  90  into groove  77 , then with further movement snaps out of groove  77  and into place in channel  91 . Further, as groove  91  provides a reduce wall cross section in the female end portion of shaft  22 , this feature may serve as a torque-limit measure. 
     FIGS. 16 and 17  illustrate schematically two similar embodiments  1400  and  1500 , respectively. Both embodiments are illustrated as they might appear prior to assembly. In embodiment  1400  of  FIG. 16 , shaft  20  includes a conical aperture  102  that mates with a solid conical terminal section  104  of shaft  22  when assembled. A threaded female section  106  inside of shaft  20  also mates with a threaded male portion  108  of shaft  22  when assembled. Undercuts  114  aid in threading and boring of threads  106  and conical aperture  102 . Another set of threads,  110  on an external portion of shaft  20 , mates with a set of internal threads  112  in coupling member  35 . Coupling member  35  may be a standard nut in this embodiment, fitted with a two piece ring  116 . A round wire snap ring  118  helps to axially secure shaft  22  to coupling member  35 . Threads  112  may serve as a torque-limiting feature, as well as materials of construction of coupling member  35 .  FIG. 17  illustrates a similar embodiment  1500 , having a straight aperture  120  in shaft  20  rather than a conical aperture  102  as in embodiment  1400  of  FIG. 16 . Straight aperture  120  accepts a pilot extension  122  of shaft  22  which bottoms out in aperture  120 . Other than these differences, embodiments  1400  and  1500  are identical. 
     FIGS. 18A-18C  illustrate yet another embodiment of the invention.  FIG. 18A  illustrates an exploded, partial cross-sectional view. In this embodiment, shaft  20  includes a threaded section  124  and a non-threaded terminal section  125 . Non-threaded terminal section  125  accepts a bolt-locking washer  126 , which in turn seats at the end  127  of a bore in the end of shaft  22 . A portion  128  of the bore is threaded to accept threaded section  124  of shaft  20 . Coupling member  35  in this embodiment may comprise a barbed nut having barbs  130  and undercuts  129  ( FIG. 18B ), allowing barbs  130  to deflect inwardly when assembled into chamfer  131  on shaft  22  and down onto threads  124  of shaft  20 . Coupling member or nut  35  has internal threads (not illustrated), and surfaces  132  allowing a wrench or other tool to turn and tighten the assembly.  FIG. 18C  illustrates the assembled apparatus, partially in cross-section. Both torque and axial forces are transferred by the threads, and additional axial force transmission is supplied by the lock washer  126  and the barbs  130  of coupling member  35 . Torque-limiting may be accomplished by materials of construction of coupling member  35 , or by any other means described herein or their functional equivalent. 
   FIGS.  19  and  19 A- 19 D illustrate another embodiment of the invention. Spline connections  28  and  30  are used for torque transfer, while internal circular push on rings  48  and  48 ′, as well as internal snap rings  50  and  50 ′ secure shafts  20  and  22  axially to coupling member  35 . Snap ring  50  fits into a groove  133  in coupling member  35 , while snap ring  50 ′ fits into a groove  85 ′ in coupling member  35 . 
   Apparatus, systems, and methods of the invention may be employed in a variety of applications, such as in horizontal pumping systems (“HPS”), such as illustrated generally in  FIG. 1 . Any of a number of drivers, such as motors, turbines, generators, and the like, may be employed. However, the HPS may comprise other pumps, such as positive displacement pumps, in conjunction with the centrifugal pump, and other drivers for a given application. As is known, centrifugal pumps will include a set of impellers and diffusers designed move fluid through the pump, perhaps toward a second or more stage having a different set of impellers and diffusers, eventually forcing fluid out through a discharge. A single pump housing may house all pump stages. 
   As explained in assignee&#39;s U.S. Pat. No. 6,425,735, the motor may be fixedly coupled to horizontal skid at a motor mount surface of the horizontal skid. The pump may be coupled to the horizontal skid by a mount assembly, which may include a support (e.g., a fixed support) and clamp assemblies. The pump may be drivingly coupled to the motor through support. Alternatively, the support may be an external conduit assembly configured for attachment to a pump conduit, such as one of two pump conduits extending from the pump. Pumping systems of the invention may displace water, salt water, sewage, chemicals, oil, liquid propane, or other fluids in through one of the pump conduits and out of another pump conduit. In addition, the temperature of the fluids may vary. For example, some applications may involve pumping hot fluids, while others may involve pumping cold fluids. In addition, the temperature may change during the pumping operation, either from the source of the fluid itself, or possibly due to the heat generated by the operation of the pump and/or driver. In addition, temperature may change dramatically due to weather change. 
   Electrical submersible pumps (“ESP”), such as pumping systems known under the trade designation Axia™, available from Schlumberger Technology Corporation, may be modified in accordance with the teachings of the invention. Pumps of this type may feature a simplified two-component pump-motor configuration, with pump having one or more stages inside a housing, and a combined motor and protector. The pump may be built with integral intakes and discharge heads. Fewer mechanical connections may contribute to faster installation and higher reliability of this embodiment. The combined motor and protector assembly, known under the trade designation ProMotor™, may be prefilled in a controlled environment, and may include integral instrumentation that measures downhole temperatures and pressures. 
   An alternative electrical submersible pump configuration in which apparatus and systems of the invention may be employed include an ESP deployed on cable, an ESP deployed on coiled tubing with power cable strapped to the outside of the coiled tubing (the tubing acts as the producing medium), and more recently a system known under the trade designation REDACoil™ having a power cable deployed internally in coiled tubing. For example, three “on top” motors may drive three pump stages, all pump stages enclosed in a housing. The pump stages may be identical in number of pump stages and performance characteristics, while some pump stages may have different performance characteristics. A separate protector may be provided, as well as an optional pressure/temperature gauge, sub-surface safety valve (SSSV) and a chemical injection mandrel. The technology of bottom intake ESPs (with motor on the top) has been established over a period of years. It is important to securely install pump stages, motors, and protector within coiled tubing, enabling quicker installation and retrieval times plus cable protection and the opportunity to strip in and out of a live well. This may be accomplished using a deployment cable, which may be a cable known under the trade designation REDACoil™, including a power cable and flat pack with instrument wire and one or more, typically three hydraulic control lines, one each for operating the lower connector release, SSSV, and packer setting/chemical injection. 
   Apparatus and systems of the invention may include many optional items. One optional feature of apparatus and systems of the invention is one or more sensors located at the protector to detect the presence of hydrocarbons (or other chemicals of interest) in the internal lubricant fluid. The chemical indicator may communicate its signal to the surface over a fiber optic line, wire line, wireless transmission, and the like. When a certain chemical is detected that would present a safety hazard or possibly damage the motor if allowed to reach the motor, the pump may be shut down long before the chemical creates a problem. 
   Typical uses of apparatus and systems of the invention will be in downhole and surface fluid transfer applications. 
   Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, no clauses are intended to be in the means-plus-function format allowed by 35 U.S.C. §112, paragraph 6 unless “means for” is explicitly recited together with an associated function. “Means for” clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.