Patent Publication Number: US-2015068007-A1

Title: Pump Plunger Alignment Device

Description:
CROSS REFERENCE TO RELATED APPLICATION S 
     Not applicable. 
     BACKGROUND 
     Field of the Invention 
     This invention relates to apparatus and methods for removal and replacement of pump plungers, such as those used in connection with mud pumps used in oil and gas well drilling and other applications. 
     What is commonly known as a “plunger pump” is a reciprocating, positive displacement pump comprising a power end and a fluid end. The power end, generally, has as its final output a reciprocating “pony rod.” The pony rod is connected to a plunger, akin to a piston in an internal combustion engine, which reciprocates in the “fluid end.” Intake valves permit fluid, whether it be drilling mud, water, or any other suitable fluid, to flow into a fluid chamber, when the plunger strokes away from the fluid chamber. When the plunger is stroked back toward the fluid chamber, the intake valves close, and the discharge valves open, permitting the fluid to be pushed out of the chamber. This sequence creates the pumping action. 
     In many applications for use of plunger pumps, including but not limited to those involving the pumping of drilling mud in connection with oil and gas well drilling, the fluid being pumped is solids-laden. As a result of the reciprocating motion in such environment, plungers periodically wear out and must be replaced. 
     Generally, removal of a plunger involves disconnecting it from the pony rod and then pulling it out through an opening in the cylinder housing, by removing a suction cover plate and retaining nut on the cylinder housing. Removal of the plunger generally poses relatively few problems. Replacement of the plunger is more problematic. Plungers can be quite heavy, for example approximately 70 lbs. apiece. The plunger must be inserted into the cylinder housing a considerable distance to enter the cylinder, then through an opening in a seal element, which fits around the plunger and provides a fluid seal around the plunger as it reciprocates back and forth in the cylinder. In order to seal properly around the plunger, the seal element must be very tight, and it is not easy to force the plunger through the opening in the seal element. Adding to the difficulty in stabbing the plunger through the seal element is the fact that the plunger is inserted a relatively large distance into a relatively inaccessible area within the cylinder head, through the cylinder chamber, then into the cylinder and into and through the seal element opening. 
     The challenge lies in aligning the heavy plunger with the seal element opening. While the forward end of the plunger is usually beveled to assist in stabbing it through the opening, it is still difficult to align the plunger properly with the opening in the seal element and overcome the resistance which the very tight fit of the seal element poses. In addition, there is the ever present risk of damaging the highly polished outer surface of the plunger by striking the interior surfaces of the pump, etc. 
     There is a need for an apparatus which supports the plunger as it is inserted through the cylinder head and into the cylinder, and aligns the plunger with the opening in the seal element to ease stabbing of the plunger through the seal element. 
     SUMMARY OF THE INVENTION 
     Apparatus embodying the principles of the present invention comprises an elongated trough member having a valley with dimensions and outer contours which engage surfaces and openings in a plunger pump. For purposes of this application, the trough member is referred to as a “plunger shoe.” The plunger shoe is inserted through the opening in the cylinder head, spans the cylinder chamber, and has a first end which rests in the cylinder of the pump. The second end of the plunger shoe comprises one or more shoulder sections with larger dimensions which engage and rest in corresponding profiles in the opening in the cylinder head. 
     When the plunger shoe is fully inserted into the pump, the inner surface of the trough valley is substantially aligned with the lower edge of the seal element opening. A plunger can then be placed in the valley of the plunger shoe and pushed forward, fully supported by the plunger shoe and substantially aligned with the seal element opening, and easily pushed through the seal element opening. A hole in the second end of the plunger shoe forms a convenient handle for insertion and removal of the plunger shoe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are views of a representative prior art plunger pump, with which the plunger shoe of the present invention may be used. 
         FIG. 3  is a perspective view in cutout of a portion of a plunger pump with the plunger shoe and a plunger in exploded position. 
         FIG. 4  is the view of  FIG. 3  with the plunger shoe in place within the pump, and a plunger in place in the plunger shoe. 
         FIG. 5  is a simplified cross section view of the cylinder and cylinder chamber section of a pump, with a plunger shoe and plunger in position to be stabbed into the seal element opening. 
         FIG. 6  is a top view of an embodiment of the plunger shoe. 
         FIG. 7  is a perspective view of one embodiment of the plunger shoe. 
         FIG. 8  is another, rotated perspective view of the plunger shoe of  FIG. 7 . 
         FIG. 9  is a perspective view of another embodiment of the plunger shoe. 
         FIG. 10  is another, rotated perspective view of the plunger shoe of  FIG. 9 . 
     
    
    
     DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS(S)  
     While various forms of plunger shoes can embody the principles of the present invention, with reference to the drawings some of the presently preferred embodiments can be described. 
       FIGS. 1 and 2  are views of a representative prior art plunger pump  10 .  FIG. 1  is a side view.  FIG. 2  is a cross section view of a representative plunger pump, in connection with which the plunger shoe of the present invention may be beneficially used. The fluid end of pump  10 , noted generally as  11 , comprises a cylinder  22 , in which plunger  20  reciprocates. A suction cover  44  and retaining nut  26  can be removed to provide access to cylinder chamber  28 , cylinder  22  and plunger  20 , including for removal and replacement of plunger  20 . As can be seen in  FIG. 2 , seal element  24  is disposed within cylinder  22 , and has an opening within which plunger  20  reciprocates. with seal element  24  providing a fluid and pressure tight seal around plunger  20 . A cylinder chamber  28  is a generally enlarged cross section area in cylinder housing  14 . Opening  25  in cylinder housing  14 , into which suction cover  44  and retaining nut  22  fit, generally has at least two diameters, with a larger diameter at the outer end, as can be seen in  FIG. 2  and in more detail in later drawings. 
       FIG. 3  is a simplified perspective view in partial cross section of fluid end  11 , with plunger shoe  30  and plunger  20  in an exploded position.  FIG. 4  is another simplified perspective view in partial cross section of fluid end  11 , with plunger shoe  30  and plunger  20  in position within cylinder  22  in preparation for stabbing plunger  20  through the opening in seal element  24 . 
       FIG. 5  is another simplified side view of a section of a plunger pump  10 , namely the fluid end  11  and cylinder housing  14  thereof. Seal element  24  is disposed in cylinder  22 . As can be seen, with plunger shoe  30  in place in cylinder  22 , plunger  20  is held and supported in cylinder  22 , and is held at substantially the elevation of the lower edge of the opening in seal element  24 ; said another way, plunger  20  is substantially axially aligned with the opening in seal element  24 . First shoulder  36  of plunger shoe  30  fits within corresponding diameters in the opening of cylinder housing  14 . 
     Referring to  FIGS. 6-8 , plunger shoe  30  comprises an elongated trough  38  comprising first and second ends  32  and  34 . A valley  40  runs the length of trough  38 . First end has width W1. Second end  34  comprises an enlarged width section  50  (with width W2), forming a first shoulder  36 . As can be seen in previous drawings, especially  FIGS. 3-5 , enlarged width section  50  and first shoulder  36  fit within opening  25  to hold plunger shoe  30  stable while plunger  20  is inserted. 
     The width W1 of trough  38  approximately corresponds to the diameter of cylinder  22 . The width W3 of valley  40  approximately corresponds to the diameter of plunger  20 . This relationship permits plunger shoe  30  to rest firmly within cylinder  22 , while supporting plunger  20  so that it is substantially axially aligned with the opening in seal element  24 .  FIG. 5  shows this arrangement. With plunger  20  so supported, it can be easily forced into the opening in seal element  24   
     Certain makes/models of plunger pumps  10  have more than two diameters in opening  25 , opening of cylinder housing  14 , for example three diameters. For such pumps, plunger shoe  30  comprises an enlarged width section  50  having two larger diameters, forming first and second shoulders  36  and  46 , as can be seen in  FIGS. 9 and 10 . 
     Preferably, enlarged width section  50  comprises a hole  42  forming a handle, facilitating placement and removal of plunger shoe  30  within cylinder  22 , and making it easy to carry, etc. 
     Use of the Plunger Shoe 
     To use plunger shoe  30  in connection with installation of a plunger  20 , plunger shoe  30  is placed within cylinder  22  of a plunger pump  10 , into the position shown in  FIGS. 4 and 5 . Plunger  20  is placed in valley  40  of trough  38 , then pushed forward until it is at least partially through the opening in seal element  24 . A lubricant such as grease may be applied to the outside of plunger  20  and/or to the valley  40  of plunger shoe  30 , to ease sliding plunger  20  thereon. Plunger shoe  30  can then be removed and further steps taken to connect the plunger to the pony arm, etc., as is well known in the art. 
     Removal of a plunger  20  may be done by substantially reversing these steps, as may be readily understood. 
     Materials, Manufacture of the Plunger Shoe 
     A variety of materials could be used to make plunger shoe  30 , including metals and non-metals such as high strength plastics, composites, etc. One preferred material is an aluminum alloy. Plunger shoe  30  can be made by a combination of techniques known in the art, including boring, machining, etc. 
     CONCLUSION 
     While the preceding description contains many specificities, it is to be understood that same are presented only to describe some of the presently preferred embodiments of the invention, and not by way of limitation. Changes can be made to various aspects of the invention, without departing from the scope thereof. For example, the dimensions of the plunger shoe, including length, outer width and valley width, can be varied to suit particular applications. The number, size, and shape of the enlarged sections may be altered to suit particular pump models. Materials may be changed to optimize manufacturing costs, etc. 
     Therefore, the scope of the invention is to be determined not by the illustrative examples set forth above, but by the appended claims and their legal equivalents.