Abstract:
The invention includes an apparatus for pumping a fluid through a reciprocating pump. Several motors are responsible for operating the pump assembly. Each of the motors has a drive shaft. The motor drive shafts are connected to a series of drive gears. The drive gears are operably connected to a single driven gear for rotating the driven gear. The single driven gear connects with the pump assembly and drives the reciprocating pump in order to force fluid through the reciprocating pump.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims the benefit under Section 119(e) of U.S. Provisional Application Ser. No. 60/466,715, filed Apr. 30, 2003, titled “Direct Drive Reciprocating Pump.” 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to reciprocating pumps, and more specifically to the drive assembly of an oilfield mud or service pump.  
         BACKGROUND OF THE INVENTION  
         [0003]    Various kinds of pumps have been used in oilfield operations. Two examples of pumps are a well service pump and a mud pump. Well service pumps are used for pumping cement or chemicals into the well and are typically mounted on a skid or a truck. Well service pumps typically operate in short time intervals, and are repeated later after servicing. Mud pumps circulate drilling mud down the borehole during drilling. Mud pumps typically operate in a continuous manner without interruption. Mud pumps also typically have a longer stroke, for which reason mud pumps tend to have a larger size and weight.  
           [0004]    One prior version of a mud pump has two electric motors, a belt, or a chain, or a single drive shaft and gear, with each electric motor having a separate drive train. In this manner, prior mud pumps were typically fairly large in size. In other prior mud pumps, a gear unit is positioned inside the pump unit rather than on the outside of the pump unit. Because the gear unit was positioned inside the pump unit, such prior versions of mud pumps were not compact in size and were also of considerable weight. Mobile service pumps normally have only a single motor, which is located on one side of the pump. It has long been a desire to reduce the size and weight of oilfield service pumps and oilfield mud pumps, without sacrificing capacity. This is particularly desirable for mobile pumps mounted on trucks or skids.  
         SUMMARY  
         [0005]    The invention includes an apparatus for pumping a fluid through a reciprocating pump. Several motors are responsible for operating the pump assembly. Each of the motors has a drive shaft. The motor drive shafts are connected to a series of drive gears. The drive gears are operably connected to a single driven gear for rotating the driven gear. The single driven gear connects with the pump assembly and drives the reciprocating pump in order to force fluid through the reciprocating pump.  
           [0006]    In one embodiment of many possible embodiments, the motors are located on one side of a longitudinal center line of the pump, and the gears are located on the opposite side of the longitudinal centerline. The motor shafts extending from the motors are parallel to each other and are perpendicular to the longitudinal centerline of the pump.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a side elevational view of the reciprocating pump assembly constructed in accordance with the present invention.  
         [0008]    [0008]FIG. 2 is a front elevational view of the reciprocating pump assembly shown in FIG. 1.  
         [0009]    [0009]FIG. 3 is a top plan elevational view of the reciprocating pump assembly shown in FIG. 1.  
         [0010]    [0010]FIG. 4 is a schematic view of the gear assembly for the reciprocating pump assembly shown in FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0011]    Referring to FIG. 1, a reciprocating pump assembly  11  includes a pump housing  13 , which encloses a crankshaft (not shown) and a crosshead (not shown) of reciprocating pump assembly  11 . Pump housing  13  extends substantially horizontal to the ground or a support surface, and away from the crankshaft (not shown) toward a piston rod housing  15  that encloses a piston rod that is attached to the crosshead. A cylinder  17  is connected to the end of piston rod housing  15  extending away from pump housing  13 . A piston (not shown) reciprocates to pump fluids through cylinder  17 . In the preferred embodiment, the crankshaft (not shown) drives three pistons (not shown) for pumping fluid through three cylinders  17 . While depicted as a triplex with three cylinders  17 , as will be readily apparent to those skilled in the art, pump assembly  11  can alternatively also have different numbers of cylinders, such as five cylinders. In the preferred embodiment, a common intake manifold  19  supplies fluid to be pumped by pump assembly  11 . A common exhaust manifold  21  receives the fluid being discharged by pump assembly  11 . A skid having a plurality of rails  23 , which are connected to reciprocating pump assembly  11  through supports  25 , support reciprocating pump assembly  11 .  
         [0012]    In the preferred embodiment, a plurality of motors  27 ,  29  drive reciprocating pump assembly  11 . Motors  27 ,  29  preferably include a forward motor  27  located substantially above pump housing  13  and offset toward cylinder  17 , and a rearward motor  29  substantially located above pump housing  13  and offset rearward farther from cylinder  17  than motor  27 . As best shown in FIG. 1, motors  27 ,  29  preferably straddle the portion of piston pump housing  13  that houses the crankshaft (not shown), and are mounted to the top of housing  13 . As shown in the top view of FIG. 3, motors  27 ,  29  are both located on one side of a longitudinal center line  30  passing through pump assembly  11 .  
         [0013]    Referring to FIGS. 2 and 3, a single gear assembly  31  is connected to motors  27 ,  29  for communicating rotational movement from motors  27 ,  29  to the crankshaft (not shown). Gear assembly  31  is located on the opposite side of centerline  30  from motors  27 ,  29 . A forward motor drive shaft  33  extends from a forward motor  27  toward gear assembly  31 , and a rearward motor drive shaft  35  extends from rearward motor  29  toward gear assembly  31 . Shafts  33 ,  35  are parallel to each other and perpendicular to centerline  30 . A forward gear shaft  37  extends toward forward motor drive shaft  33 , and a rearward gear shaft  39  extends toward rearward motor drive shaft  35 . A flexible coupling  41  connects forward motor drive shaft  33  to forward gear shaft  37 . Likewise, another flexible coupling  41  connects rearward motor drive shaft  35  with rearward gear shaft  39 . Gear assembly  31  receives rotational movement from motors  27 ,  29  and translates the rotational movement to a single gear shaft  51  (FIG. 4), which drives the crankshaft (not shown) of reciprocating pump assembly  11 . In the preferred embodiment, drive shafts  33 ,  35  connect to gear assembly  31  at an elevation above pump housing  13 , and gear assembly  31  translates rotational movement to the crankshaft (not shown) at an elevation substantially the same as pump housing  13 .  
         [0014]    Referring to FIG. 4, an inside portion of gear assembly  31  is shown schematically in more detail. In the preferred embodiment, an forward pinion  43  is located on the end of forward gear shaft  37  extending away from coupling  41  (FIG. 3). A rearward pinion  45  is located on the end of rearward gear shaft  39  extending away from the other flexible coupling  41  (FIG. 3). In the preferred embodiment, forward pinion  43  and rearward pinion  45  are at substantially the same elevation and positioned a pre-selected distance apart. In the preferred embodiment, an intermediate gear  47 , which is offset and located substantially below forward pinion  43 , engages forward pinion  43  so that intermediate gear  47  rotates as forward motor  27  rotates forward gear shaft  37  forward pinion  43 . In the preferred embodiment, another intermediate gear  47  is also located substantially below and offset from rearward pinion  45  so that rearward motor  29  rotates rearward pinion  45  and intermediate gear  47 . In the preferred embodiment, intermediate gears  47  are located a pre-selected distance apart from each other and are closer together than forward and rearward pinions  43 ,  45 . In the preferred embodiment, intermediate gears  47  are larger in diameter than pinions  43 ,  45  so that the rotational velocity of intermediate gears  47  is smaller than the rotational velocity of pinions  43 ,  45 .  
         [0015]    A main gear  49 , located substantially between and below intermediate gears  47 , is engaged by each of intermediate gears  47  so that intermediate gears  47  translate rotational movement to main gear  49  when pinions  43 ,  45  rotate. In the preferred embodiment, intermediate gear  47  and forward pinion  43  are offset so that the center points of forward pinion  43 , intermediate gear  47 , and main gear  49  are substantially linear. Rearward pinion  45  and intermediate gear  47  are also offset so that the center points of rearward pinion  45 , intermediate gear  47 , and main gear  49  align substantially linearly. In the preferred embodiment, the arrangement of pinions  43 ,  45 , intermediate gears  47 , and main gear  49  is substantially V-shaped. A gear shaft  51  extends from main gear  49  and connects to the crankshaft (not shown) extending through pump housing  13  for driving pump assembly  11 . In the preferred embodiment, main gear  49  is substantially larger than each intermediate gear  47 , thereby also reducing the rotational velocity of gear shaft  51  relative to pinions  43 ,  45 .  
         [0016]    In operation, motors  27 ,  29  receive an electrical current. Motors  27 ,  29  rotate motor drive shafts  33 ,  35  extending substantially parallel to each other from motors  27 ,  29 . Flexible couplings  41  connect motor drive shafts  33 ,  35  to gear shafts  37 ,  39  extending toward gear assembly  31 . Motor drive shafts  33 ,  35  translate rotational movement from motors  27 ,  29  to gear shafts  37 ,  39 . Gear shafts  37  and  39  rotate pinions  43 ,  45 , which in turn engage each of their respective intermediate gears  47 . As is evident from FIG. 4, the rotational velocity of each intermediate gear  47  is less than the rotational velocity of either pinions  43  or  45 . Each intermediate gear  47  engages main gear  49  to translate rotational movement to gear shaft  51 . Gear assembly  31 , through pinions  43 ,  45 , intermediate gear  47 , and main gear  49 , translates rotational movement from motors  27 ,  29 , while reducing the rotational speed of gear shaft  51  extending out of gear assembly  31 .  
         [0017]    The invention offers important advantages associated with the positioning of the gear unit on the outside of the pump unit rather than inside the pump unit itself. In this respect, the invention provides the pump with a more compact size and lighter weight. It provides easier mobility and transport for use in mobile oil rigs, resulting from the smaller size and lighter weight. The invention would provide for more convenient service to the pump, and thus less spare parts resulting from operation breakdowns. In summary, the invention provides a more efficient and reliable pump assembly that enhances overall performance.  
         [0018]    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, the different arrangement of gears inside of gear assembly  31  could be utilized to perform substantially the same functions of translating rotational movement to the crankshaft (not shown) of reciprocating pump assembly  11  with additional intermediate gears, or a different arrangement of pinions  43 ,  45  so that they are not substantially V-shaped while still providing enough space for the placement of more than one motor.  
         [0019]    Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.