Abstract:
A debris evacuation apparatus and method evacuates debris in a pumping system that forms between the plunger exterior and barrel interior. The apparatus has at least one seal and one groove located south of the seal, with the seal blocking northward travel of debris and directing it to the groove. Ports within the groove permit debris to enter the debris evacuation apparatus. Interior to the debris evacuation apparatus, the entering debris will become mixed with pumped fluid, and will be drawn out of the pumping system with the pumped fluid. The pumped fluid passing through the debris evacuation apparatus will be caused to rotate by an interior section located at a south portion of the debris evacuation apparatus, utilizing a plurality of angled veins surrounding a closed center section located at a north end of the interior section.

Description:
RELATED APPLICATION 
   This is a continuation-in-part of Ser. No. 10/632,201, filed Jul. 30, 2003 now U.S. Pat. No. 7,008,197 in the name of the same inventor hereof, and to which priority is claimed. 

   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   This invention relates generally to oil pumps and, more specifically, to a debris evacuation apparatus and method that is intended to extend plunger and barrel life. 
   2. Background of the Invention 
   In general terms, an oil well pumping system begins with an above-ground pumping unit, which creates the up and down pumping action that moves the oil (or other substance being pumped) out of the ground and into a flow line, from which the oil is taken to a storage tank or other such structure. 
   Below ground, a shaft is lined with piping known as “tubing.” Into the tubing is inserted a sucker rod, which is ultimately, indirectly, coupled at its north end to the pumping unit. Below the sucker rod are located a number of pumping system components, including the cage and, below the cage, the plunger. The plunger operates within a barrel, which barrel is positioned within the tubing. 
   The amount of space between the exterior surface of the plunger and the interior surface of the barrel can be as great as 0.01″. This space allows a constant passage of fluid, including debris, between the plunger exterior and the barrel interior. The debris that is contained within the fluid and that passes through the space between plunger and barrel scores the plunger and the barrel, reducing the operating life of both. 
   A need therefore existed for an apparatus and method that will evacuate debris from the space that is between the plunger and the barrel, so as to extend the operating life of each of these two pumping system components. The present invention addresses this need and provides other, related, advantages. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an apparatus and method that will evacuate debris from the space that is between the plunger and the barrel, so as to extend the operating life of each of these two pumping system components. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective of a debris evacuation apparatus consistent with an embodiment of the present invention. 
       FIG. 2  is a side, cross-sectional view of the apparatus of  FIG. 1 , taken along line  2 - 2 . 
       FIG. 3  is a top view of the apparatus of  FIG. 1 . 
       FIG. 4  is a bottom view of the apparatus of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring first to  FIGS. 1-2 , an embodiment of the debris evacuation apparatus  10  of the present invention is shown. In describing the structure of the apparatus  10  and its operation, the terms “north” and “south” are utilized. The term “north” is intended to refer to that end of the pumping system that is more proximate the pumping unit, while the term “south” refers to that end of the system that is more distal the pumping unit, or “downhole.” 
   Beginning from the north end (the top in the drawing figures), the main exterior topography of this embodiment of the apparatus  10 , which has a substantially cylindrical external configuration, includes the following: (a) an external threaded section  12 ; (b) a collar area  14 ; (c) an upper seal  16 ; (d) an upper groove  18 ; (e) ports  20 ; (f) a lower seal  22 ; (g) a lower groove  24 ; and (h) a main shaft  26 . The length of the apparatus  10  can range from approximately six inches to six feet or more. 
   Referring to  FIGS. 2-4 , looking now interiorly, it can be seen that preferably there is an interior section  28  located within the main shaft  26 . (It should be noted that the interior section  28  may be threadably engaged within the main shaft  26  or, alternatively, may be formed through a machining process or the like as an integral, one-piece portion of the apparatus  10 .) In one embodiment, the interior section  28  is threadably engaged by internal threaded section  30 . The interior section  28  preferably is closed about an upper, center section  32 , which section  32  is surrounded by one or more and preferably four directional veins  34  (see  FIG. 4 ). (It would be possible, it should be noted, to provide an open center section  32 .) The veins  34  are angled, so as to impart rotation to fluid passing therethrough, as discussed below. The interior section  28  is positioned below an expansion chamber  36 , which is an area of increased diameter within the main shaft  26 . Above the expansion chamber  36  is a passage  38 , having a diameter that is less than that of the expansion chamber  36 . It can be seen that the ports  20  extend through to the passage  38 . 
   The seals  16  and  22  are preferably formed of a pressure actuated or elastic wiper seal type of material, although other suitable sealing materials could be utilized. The seals  16  and  22  should be positioned, and dimensioned, so as to contact the interior of the barrel, forming a seal. (It should be noted that it would be possible to entirely eliminate seals  16  and  22 , while still preserving much of the functionality of the apparatus  10  as described herein.) 
   The tolerance between the exterior of the main shaft  26  and the interior of the barrel should be approximately 0.002″—i.e., substantially less than the approximately 0.01″ tolerance commonly seen between the plunger and barrel. This configuration permits the main shaft  26  to act as a guide for the seals  16  and  22 , thus taking from the seals  16  and  22  some of the side load. 
   The preferred placement of the apparatus  10  within a pumping system will now be described. It is preferred to couple the north end of the apparatus  10  to the south end of the open cage, by inserting external threaded section  12  into a mating threaded region within the south end of the open cage. It is preferred to couple the south end of the apparatus  10  to the north end of the plunger, by inserting the threaded north end of the plunger into the internal threaded section  30 . As can be seen in  FIG. 2 , sufficient space should be provided below the interior section  28  to permit insertion of the north end of the plunger. (It should be noted that it would be possible to provide the apparatus  10  as an integral portion of one-piece assembly that includes both the apparatus  10  and the plunger, as opposed to making the two components detachable one from the other. In such an embodiment, the combined apparatus  10  and plunger would have an extended length.) 
   It should be noted that, instead of positioning the interior section  28  interior to the main shaft  26 , it would be possible to position it below the main shaft  26 . In such a configuration, it would be desirable to provide a threaded exterior space at the north end of the interior section  28 , to be inserted into the south end of the apparatus  10 , and a threaded interior space at the south end of the interior section  28  of sufficient dimension to receive the north end of the plunger. Alternatively, in a configuration of the apparatus  10  in which the interior section  28  is positioned below the main shaft  26 , it would be possible to provide male threading on both ends of the interior section  28 , with coupling female threading provided on the south end of the main shaft  26  and north end of the plunger. 
   Further description and explanation of the features of the apparatus  10  and its use will be provided in connection with a description of the operation of the apparatus  10  during a typical pumping operation. 
   First, it should be noted that upward movement of the pumped fluid occurs during the downstroke. Referring now to  FIG. 2 , during the downstroke, fluid will enter through the south end of the apparatus  10 . The fluid will enter the interior of the interior section  28 . It will continue northward, until contacting the center section  32 . The upward movement of the fluid will be directed by the center section  32 , causing it to change direction and to enter the veins  34  so as to be able to continue the upward travel. 
   The angling of the veins  34  imparts rotational movement to the fluid as it passes therethrough. The fluid, which is now in rotation, enters the expansion chamber  36 . The increase in diameter causes an increase in the velocity of the rotating fluid. The fluid continues to rotate as it travels upward, through the passage  38 . The rotation of the fluid creates a vortex, with an area of lower pressure in the interior of the vortex. 
   Northward travel of debris located exterior to the apparatus  10  and below seal  22  will be blocked by seal  22 . The debris will enter the lower groove  24 , and will be drawn through the port  20 . The drawn-in debris then joins the fluid traveling upward through the apparatus  10 , and is pumped out. In the event that seal  22  becomes worn or otherwise in the event that debris enters the area above seal  22 , debris will be blocked by seal  16  and enter upper groove  18 , and be drawn in through ports  20  therein, as herein-described. 
   It can be seen that it would be possible to eliminate the upper groove  18  and seal  16  (including the ports  20  associated with the upper groove  18 ), while still providing a substantial improvement in debris removal. Alternatively, the lower grove  24  and seal  22  could be eliminated, with only the upper groove  18  and seal  16  provided. It may also be desired to provide more than two grooves and seals. 
   Attention is now directed to collar area  14 . The purpose of the inwardly angled collar area  14  is to trap larger debris located north of the apparatus  10 . On the upstroke, such debris will become trapped within the collar area  14 , while smaller debris is allowed to travel southward and become more evenly distributed over a larger areas of the exterior surface of the apparatus  10  and plunger—thereby limiting the risk of sticking caused when large amounts of debris become trapped between the plunger and barrel. On the downstroke, the debris will mix with pumped fluid coming out of the cage, and will be drawn up the barrel. While it is preferred to have a collar area  14  to further optimize debris removal, it would be possible to provide substantial improvement in debris removal without providing the collar area  14 . In one embodiment, the collared area has a diameter, when measured from the base of the inward angled portion thereof, that is approximately eight one-thousands of an inch less than the diameter of the main shaft  26 . 
   It may also be desired to provide a collar area on the south end of the apparatus  10  as well as on its north end, to further improve debris removal. In this embodiment, the south collar area would be formed in the south end of the main shaft  26 . 
   While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.