Abstract:
A reciprocating pump assembly includes piston rod that is movable and reciprocates in order to pump a fluid. The piston rod has a piston portion at an end that stokes within a piston chamber. The pump assembly also includes a piston rod sleeve that houses the piston rod. The piston rod sleeve does not reciprocate with the piston rod. Thus, the piston rod sleeve remains stationary. The piston rod sleeve defines and annulus between the piston rod and the piston rod sleeve. The pump assembly has a fluid line that leads into the annulus. The fluid line delivers coolant to the annulus. The pump assembly also includes a flow passage. The flow passage has an inlet in fluid communication with the annulus for receiving the coolant. The passage also has an outlet in fluid communication with the piston chamber for delivering the coolant.

Description:
RELATED APPLICATIONS 
   This nonprovisional patent application claims the benefit of co-pending, provisional patent application U.S. Ser. No. 60/476,746, filed on Jun. 6, 2003, which is hereby incorporated by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to reciprocating pumps, more specifically to a coolant system for the piston and liner of the reciprocating pumps. 
   2. Background of the Invention 
   In oil field operations, reciprocating pumps are often used for various purposes. Some reciprocating pumps, generally known as “mud pumps,” are typically used for well drilling operations. During operation, the pistons and liners of the pumps generate large amounts of heat due to friction. It is desirous to cool the liners and pistons in order to extend their operation lives, which in turn increases overall efficiency and reduces down-time for maintenance. 
   Prior systems for cooling pistons and liners includes various coolant injector systems. For example, in one system, a coolant line or hose is physically coupled to the piston rod with a the hose feeding into the piston. The coolant hose moves with the piston rod during operations. The hose in this system typically has a short life due to wear associated with moving with the piston rod. Another system includes a hose that connects to an outer surface of the piston rod that transmits the coolant through the piston rod to a sprayer located in the piston rod adjacent the piston. The hose in this assembly also has problems with wear because the hose connects to and reciprocates with the piston rod. 
   SUMMARY OF THE INVENTION 
   In this invention, a reciprocating pump assembly includes piston rod that is movable and reciprocates in order to pump a fluid. The piston rod has a piston portion at an end that stokes within a piston chamber. The pump assembly also includes a piston rod sleeve that houses the piston rod. The piston rod sleeve does not reciprocate with the piston rod, so the piston rod sleeve remains stationary. The piston rod sleeve also defines and annulus between the piston rod and the piston rod sleeve. The pump assembly has a fluid line that leads into the annulus. The fluid line delivers coolant to the annulus. The pump assembly also includes a flow passage. The flow passage has an inlet in fluid communication with the annulus for receiving the coolant. The passage also has an outlet in fluid communication with the piston chamber for delivering the coolant. 
   The flow passage of the pump assembly may be located within the piston rod. As such, the coolant flows through an interior of the piston rod between the inlet and outlet of the flow passage. The pump assembly can also include a fluid sprayer. The sprayer is typically located at the outlet of the flow passage in order to deliver a spray of fluid into the piston chamber. 
   The piston rod can include an outer shell that has an inner circumference. The piston rod can also include a pony rod that is located within the outer shell and has an outer circumference that is less than inner circumference of the outer shell. The pony rod and the outer shell define a clearance between the inner surface of the outer shell and the outer surface of the pony rod. The clearance can be a portion of the flow passage for carrying the coolant from the annulus and the piston chamber. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic elevational view of a reciprocating pump assembly constructed in accordance with this invention. 
       FIG. 2  is a top plan schematic view of the reciprocating pump assembly shown in  FIG. 1 . 
       FIG. 3  is a sectional view of a portion of the pump assembly shown in  FIG. 1 . 
       FIG. 4  is an enlarged sectional view of a portion of the pump assembly shown in  FIG. 1 . 
       FIG. 5  is an enlarged portion of the portion of the pump assembly shown in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a reciprocating pump  11  includes a crankshaft housing  13  that comprises a majority of the outer surface of reciprocating pump  11  shown in  FIG. 1 . A piston rod housing  15  attaches to a side of crankshaft housing  13  and extends to a piston chamber or cylinder  17 . Cylinder  17  preferably includes a fluid inlet  19  and a fluid outlet  21  ( FIG. 2 ). 
   Referring to  FIG. 2 , piston rod housing  15  is segmented into three portions, each portion comprising a piston throw  23 . Reciprocating pump  11  as shown in  FIG. 2  has three piston throws  23 , which is commonly know as a triplex, but could also be segmented for five piston throws  23 , which is commonly known as a quintuplex pump. The description focuses on a triplex pump, but as will be readily apparent to those skilled in the art, the features and aspects described are easily applicable for pumps with various numbers of piston throws  23 . Each piston throw  23  houses a piston rod  33  ( FIG. 3 ) extending toward cylinder  17 . As shown in  FIG. 2 , each piston throw  23  extends in the same longitudinal direction from crankshaft housing  13 . 
   Referring to  FIG. 3 , a portion of reciprocating pump  11  housed within crankshaft housing  13  is shown. Crankshaft housing  13  houses a crankshaft  25 , which is typically connected to a motor (not shown). The motor (not shown) rotates crankshaft  25  in order to drive reciprocating pump  11 . In the preferred embodiment, crankshaft  25  is cammed so that fluid is pumped from each piston throw  23  at alternating times. As is readily appreciable by those skilled in the art, alternating the cycles of pumping fluid from each of cylinders  17  helps minimize the primary, secondary, and tertiary (et al.) forces associated with reciprocating pump  11 . In the preferred embodiment, a connector rod  27  includes an end that connects to crankshaft  25  and another end that engages a crosshead  29 . Connector rod  27  connects to crosshead  29  through a crosshead pin  31 , which holds connector rod  27  longitudinally relative to crosshead  29 . Connector rod  27  pivots about crosshead pin  31  as crankshaft  25  rotates with the other end of connector rod  27 . A piston rod  33  extends from crosshead  29  in a longitudinally opposite direction from crankshaft  25 . Connector rod  27  and crosshead  29  convert rotational movement of crankshaft  25  into longitudinal movement of piston rod  33 . A crosshead housing  32 , located in crankshaft housing  13 , extends longitudinally away from crankshaft  25 . In the preferred embodiment, crosshead housing  32  guides crosshead  29  as crosshead  29  reciprocates longitudinally relative to crankshaft  25 . 
   Referring to  FIG. 4 , a piston portion  35  connects to piston rod  33  for pumping the fluid passing through reciprocating pump  11 . As illustrated in  FIG. 4 , piston portion  35  is a piston. Cylinder  17  ( FIG. 1 ) connects to the end of piston rod housing  15  extending away from crankshaft housing  13  ( FIG. 1 ). Cylinder  17  typically includes a cylinder chamber, which is where the fluid being pumped by reciprocating pump  11  is pressurized by piston  35 . Piston rod  33  preferably includes an outer shell or outer casing  37  and a pony rod  39 , that are each connected to and extending away from crosshead  29 . Pony rod  39  is preferably a solid shaft having a threaded profile toward the end extending away from crosshead  29 . Outer casing  37  preferably encloses a substantial portion of pony rod  39 , thereby defining a rod annulus  40  in the area between pony rod  39  and outer casing  37 . 
   Piston rod  33  also preferably includes a tubular extension or extension rod  41  connected to the ends of pony rod  39  and outer casing  37 . Extension rod  41  extends longitudinally away from crankshaft  25  ( FIG. 3 ) to connect piston rod  33  with piston  35 . Piston rod  33  also preferably includes a rod clamp assembly  43  that connects extension rod  41  with the ends of outer casing  37  and pony rod  39 . In the preferred embodiment, rod clamp assembly  43  includes an intermediate casing  45  that abuts an end portion of outer casing  37  and receives a portion of pony rod  39 . A portion of intermediate casing  45  is flared so that the outer diameter of intermediate casing  45  located toward the end extending away from crankshaft  25  is greater than other portions of intermediate casing  45 . Extension rod  41  also has a flared portion located toward the end of extension rod  41  that is being connected to pony rod  39  and outer casing  37 . 
   The flared portions of intermediate casing  45  and extension rod  41  abut and are held relative to each other by an outer clamp  47 . Outer clamp  47  encloses the interface of intermediate casing  45  and extension rod  41 . Outer clamp  47  has a recess portion which surrounds the flared portions of extension rod  41  and intermediate casing  45 . Therefore, as outer casing  37  reciprocates longitudinally toward and away from crankshaft  25 , extension rod  41  must also reciprocate toward and away crankshaft  25 . 
   In the preferred embodiment, extension rod  41  is a tubular member which also receives and encloses a portion of pony rod  39 . Preferably an inner sleeve  49 , having a threaded profile that matingly engages with the threaded profile located toward the end of pony rod  39  extending away from crankshaft  25 , is positioned at the interface of intermediate casing  45  and extension rod  41 . Intermediate casing  45  preferably includes an inner bore which receives a portion of inner sleeve  49  and prevents inner sleeve  49  from moving relative to intermediate casing  45  closer to crankshaft  25 . Extension rod  41  also preferably has an inner bore which receives a portion of inner sleeve  49 , which prevents inner sleeve  49  from moving relative to extension rod  41 . In the preferred embodiment, an extension rod annulus  50  is defined between piston  35 , inner sleeve  49 , the end of pony rod  39  extending away from crankshaft  25 , and the interior of extension rod  41 . Piston  35  connects to the end of extension rod  41  extending away from rod clamp assembly  45 . In the preferred embodiment, a plurality of passages  51  extend longitudinally through inner sleeve  49 , between rod annulus  40  and extension rod annulus  50 , around the threaded portion of pony rod  39  so that rod annulus  40  and extension annulus  50  are in fluid communication through rod clamp assembly  43 . 
   A piston liner  55  adjoins to an interior surface of cylinder  17 . In the preferred embodiment, piston liner  55  is in fluid communication with an interior portion of cylinder  17  and thereby defining a pumping chamber of reciprocating pump assembly  11 . Piston  35  slidingly engages piston liner  55  as piston  35  reciprocates longitudinally toward and away from crankshaft  25 . Reciprocating piston  35  within piston liner  55  causes the volume of the pumping chamber to increase and decrease as piston  35  reciprocates longitudinally toward and away from crankshaft  25 , thereby positively displacing the fluid being pumped through reciprocating pump  11 . 
   Piston  35  typically experiences wear from the heat created by sliding engagement of piston liner  55  during normal pumping operations. Typically the fluid being pumped through the pumping chamber of reciprocating pump  11  helps to lubricate and cool the portion of piston liner  55  on the cylinder side of piston  35 . A coolant assembly  57  provides coolant to the crankshaft  25  side of piston  35  to prevent excessive heat and wear between piston  35  and piston liner  55 . In the preferred embodiment, coolant assembly  57  preferably includes a piston rod sleeve or coolant sleeve  59  extending between crosshead housing  32  and the portion of crankshaft housing  13  that engages piston rod housing  15 . Coolant sleeve  59  preferably encloses outing casing  37  of piston rod  33  and is stationary. Seals  61  preferably seal the end of coolant sleeve  59  adjacent crosshead housing  32  and the end of connector sleeve  59  adjacent rod clamp assembly  43 . The interior surface of coolant sleeve  59  and seals  61  thereby define a sleeve annulus  63  surrounding outer casing  37  of piston rod  33 . In the preferred embodiment, a fluid line or injector hose  65  injects a coolant into sleeve annulus  63  through a sleeve port  67  extending through a side of sleeve  59 . Injector hose  65  typically extends away from lubricator sleeve  59  to an outer surface of crankshaft housing  13  to receive the coolant from a coolant source (not shown). 
   In the preferred embodiment, seal  61  located adjacent crosshead housing  32  is placed a predetermined distance from seal  61  located adjacent the end of crankshaft housing  13  extending away from crankshaft  25 , such that the distance between seals  61  is greater than or substantially equal to the length of the stroke of piston  35 . In the preferred embodiment, an outer shell or casing port  69  extends through a side of outer casing  37  of piston rod  33 . Rod annulus  40  and sleeve annulus  63  are in full communication through outer casing port  69 . Rod annulus  40  and sleeve annulus  63  are in fluid communication throughout the entire stroke length of the piston rod. In the preferred embodiment, outer casing port  69  is formed on a portion of outer casing  37  such that outer casing port  69  is always substantially between seals  61  during operations of reciprocating pump  11 . Therefore, coolant from injector hose  65  that accumulates in sleeve annulus  63  can readily communicate through outer casing port  69  into rod annulus  40  while piston rod  33  reciprocates toward and away from crankshaft  25 . In the preferred embodiment, the coolant that communicates from sleeve annulus  63  through outer casing port  69  travels along pony rod  33  toward passages  51  and inner sleeve  49 . The coolant communicates through passages  51  from rod annulus  40  and into extension annulus  50  toward piston  35 . 
   Referring to  FIGS. 4 and 5 , a spray port  71  is formed in extension rod  41  at a position adjacent piston  35 . An injector sprayer  73  is preferable located within a spray port  71 . Spray port  71  and injector sprayer  73  are preferably angled so that coolant is sprayed along the crankshaft  25  ( FIG. 3 ) side of piston  35  and piston liner  55 . Therefore, in the preferred embodiment the coolant flows from sleeve annulus  63  through a continues passage that includes outer casing port  69 , rod annulus  40 , passages  51  within clamp assembly  43 , extension annulus  50  and spray port  71 . This flow passage is merely a preferred embodiment, and as will be readily appreciated by those skilled in the art, this passageway is subject change due to slight variations. 
   Coolant assembly  57  advantageously provides coolant to the crankshaft  25  side of piston  35  and piston liner  55 . This reduces excessive heat and wear between piston  35  and piston liner  55 . Coolant assembly  57  also advantageously provides and assembly in which fluid line or fluid hose  65  remains stationary during pump operations. Therefore, hose  65  is not subject to the reciprocating movements that cause wear and failure in previous cooling assemblies. Accordingly, pumping operations can continue for longer periods of time between replacement of the fluid hose  65 . 
   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 without departing from the scope of the invention. For example, injector hose  65  can extend from lubricator sleeve  59  toward a side portion of crankshaft housing  13  as shown in  FIG. 4  or toward a lower portion of crankshaft housing  13  as shown in  FIG. 3  to receive coolant fluid from a coolant source (not shown). A further example that can be readily appreciated by those still in the art, while the invention has only been shown with respect to mud pumps, the same lubrication system can also be easily adapted for service pumps using a piston attached to a pony rod.