Abstract:
A connecting rod including shaft with a major flange projecting outwardly from one of its ends and a minor flange projecting outwardly from the other of its ends. The major flange and the minor flange each have a number of holes for the passage of threaded fasteners. Abutting the minor flange is a ring with a transverse aperture. A number of threaded fasteners releasably join the shaft and the link together.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to machine elements and, more particularly, to pitmans and connecting rods.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is difficult to produce oil and gas in an economic manner from low permeability reservoir rocks. Production rates are often boosted by resorting to hydraulic fracturing, a technique that increases rock permeability by opening channels through which reservoir fluids can flow to recovery wells. During hydraulic fracturing, a fluid is pumped into the earth under high pressure where it enters a reservoir rock and fractures it. Proppants are carried in suspension by the fluid into the fractures. When the pressure is released, the fractures partially close on the proppants leaving channels for oil and gas to flow.  
           [0003]    Specialized pumps are used to develop the pressures necessary to complete a hydraulic fracturing procedure or “frac job.” These pumps are usually provided with connecting rods that join a crosshead to a plunger that pressurizes a fluid. A conventional connecting rod is cast as a single unit and machined to desired tolerances. When portions of such a connecting rod wear out, the rod must be replaced in its entirety—a time-consuming, wasteful and costly undertaking. Multi-piece connecting rods have been developed as a substitute for one-piece rods with the purpose of permitting just the worn portions of a rod to be removed. Unfortunately, multi-piece rods have not gained widespread acceptance since wear has tended to occur not only in the usual locations, but, also, at the junctions between the joined pieces. Thus, the known multi-piece connecting rods, like the one-piece rods they were meant to supplant, often require a full replacement when partially worn.  
         SUMMARY OF THE INVENTION  
         [0004]    In light of the problems associated with the known connecting rods, it is a principal object of the invention to provide a new connecting rod with two portions that can be easily disconnected from one another for replacement when worn. Once disconnected from one another, a worn portion can be removed and replaced while the other portion remains in place in a pump, thus saving time and money. Disconnection can be accomplished with ordinary tools and with minimal training.  
           [0005]    It is another object of the present invention to provide a connecting rod of the type described that has a solid, self-aligning connection between its two principal portions. Such a connection impedes wear where the two portions contact one another and ensures that set-up will be proper prior to use.  
           [0006]    It is another object of the invention to provide a connecting rod of the type described whose principal portions are integrally formed. Lacking welds and other mechanical connectors, each rod portion is designed for maximum strength.  
           [0007]    It is an object of the invention to provide improved elements and arrangements thereof in a connecting rod for the purposes described which is lightweight in construction, inexpensive to manufacture, and dependable in use. Although the connecting rod is described as being of particular utility in oilfield pumps, it is anticipated that it will provide like benefits in other reciprocating engines and machines.  
           [0008]    Briefly, the connecting rod in accordance with this invention achieves the intended objects by featuring a tubular shaft with a cylindrical section and a gusset section whose wall thickness varies with length. A major flange projects from the outer end of the gusset section whereas a minor flange projects from the outer end of the cylindrical section. The major and minor flanges have holes for the passage of threaded fasteners. A link has an alignment plug for insertion into a socket in the outer end of the cylindrical section of the shaft. A ring is secured to the alignment plug. A number of threaded fasteners releasably join the shaft and the link.  
           [0009]    The foregoing and other objects, features and advantages of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention may be more readily described with reference to the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is a side elevational view of a connecting rod in accordance with the present invention with portions broken away to reveal details thereof.  
         [0012]    [0012]FIG. 2 is a top view of the connecting rod of FIG. 1 with portions broken away.  
         [0013]    [0013]FIG. 3 is a bottom view of the connecting rod.  
         [0014]    Similar reference characters denote corresponding features consistently throughout the accompanying drawings. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring now to the FIGS., a connecting rod in accordance with the present invention is shown at  10 . Connecting rod  10  includes a shaft  12  having major and minor flanges  14  and  16  at its opposed ends. Major flange  14  is configured for attachment to a bearing housing  18  and minor flange  20  is configured for attachment to a crosshead link  20 . Link  20  has an alignment plug  22  for insertion into a socket  24  in the center of minor flange  16 . A ring  26  is integrally formed with plug  22  and has a transverse aperture  28  for receiving a crosshead pin (not shown). A number of bolts  30  penetrating minor flange  16  and ring  26  releasably fasten shaft  12  and link  20  together.  
         [0016]    Shaft  12  comprises an elongated, hollow tube whose outer and inner diameters vary along its length. As shown, shaft has a cylindrical section  32  with a constant outer diameter from which a gusset section  34  with a gradually increasing outer diameter extends to reinforce major flange  14 . A passageway  36  extends through shaft  12  and is enlarged in terms of diameter at both of its ends so as to form sockets  24  and  38  for receiving alignment plugs  22  and  40  of link  20  and bearing housing  18 . A peripheral wall  42  extends inwardly from cylindrical section  32  into passageway  36  and serves as an abutment for plug  22  and a reinforcement for shaft  12  adjacent flange  16 .  
         [0017]    Major flange  14  is an outwardly projecting rim for strengthening the connection between shaft  12  and bearing housing  18 . For compactness, major flange  14  is provided with clipped, linear sides  44  that limit its outward projection from shaft  12  to front and back projections  46  and  48 . Projections  46  and  48  are each provided with a plurality of holes  50  arrayed around gusset section  34 . The centers of four holes  50  are arrayed to define a square. Through holes  50 , bolts  52  are extended for threaded attachment to bearing housing  18 .  
         [0018]    Minor flange  16  is an outwardly projecting rim for strengthening the connection between shaft  12  and link  20 . Preferably, minor flange  16  is provided with an outline resembling a square whose sides  54  are parallel to sides  44  of major flange  14 . Each of the four corners of flange  16  is provided with a hole  56  through which a bolt  30  is extended for threaded attachment to link  20 . The centers of holes  56  define a square whose sides are parallel to that extending through the centers of four holes  50 .  
         [0019]    Alignment plug  22  is a solid cylinder that fits snugly and fully into socket  24  so as to assure proper centering of link  20  on shaft  12 . Plug  22  projects from a flat surface  58  in the base of ring  26 . Preferably, four, threaded bores  60  penetrate surface  58  adjacent plug  22  and are positioned for alignment with holes  56  for the passage of bolts  30 . When bolts  30  are firmly tightened in bores  60 , the longitudinal axis of transverse aperture  28  is oriented at right angles to sides  44  and  54  of flanges  14  and  16 . To supply a flow of lubricant to aperture  28  and a crosshead pin within it, an opening  62  is provided in ring  26  opposite surface  58 .  
         [0020]    From the foregoing, it will be appreciated that the use of connecting rod  10  is straightforward. Installation of connecting rod  10  in a pump is accomplished in a conventional a manner with shaft  12  and link  20  being joined by bolts  30 . After the pump has been run for substantial period, link  20  may show signs of wear about aperture  28  that serves as a bearing surface. (Shaft  12  is unlikely to show any wear since movement of bearing housing  18  and link  20  relative to flanges  14  and  16  during use is nil.) By untightening bolts  30  and manipulating the driving mechanism of the pump, a worn link  20  can be removed from shaft  12  and replaced by an unworn link  20 . Reinstalling bolts  30  in the new link  20 , permits the pump to be energized and operated. Since rod servicing does not require the removal of bearing housing  18  from the pump, it can be completed in substantially less time than is required with conventional connecting rods. Also, since only the worn link  20  is replaced, the waste of material that accompanies the removal of the shaft and bearing housing of a conventional connecting rod from a pump is eliminated.  
         [0021]    While the invention has been described with a high degree of particularity, it will be appreciated by those skilled in the art that modifications may be made thereto. Therefore, it is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims.