Patent Application
20080011487
The linear drive motor assembly 102 controls the pump actuator 104 for use in fluid pumping. Example actuators include a reciprocating air-driven cylinder, a hydraulically-driven cylinder, a mechanically-driven actuator, and an electrically-driven cylinder. The linear drive motor assembly 102 may have a fixed travel distance with a fixed or adjustable cycle rate, for example. In yet other examples, the drive assembly 102 may have a variably-traveling cylinder and/or a fixed cycle rate or a windmill.
A hollow cylindrical casing or riser pipe 112 for channeling liquid extends into the well casing 110 at the geological site, and includes an upper end 114 and a lower end 115. Although not shown, a hollow casing liner or sleeve may be used to line the casing 110 and improve piston rod movement. The ends of both the well casing 110 and the liner would permit liquid to pass through them during operation of the device. A discharge opening 116 of a discharge tee 117 is disposed near an upper end of the well casing 110 and sealably coupled to the well head 111 for removal of the liquid being pumped. The discharge opening 116 may be connected to a discharge conduit, for example, through which the liquid elevated from the well may be removed for subsequent collection, analysis, consumption, disposal, or the like.
An actuating rod 118, also known as the drive rod, piston rod, or sucker rod, is shown axially disposed within the casing 110. The actuating rod 118 has an upper end 120 and a lower end 122. The actuating rod 118 may be formed of materials such as those used for the casing 110, for example and not by way of limitation. The rod 118 may be a chrome-plated stainless steel or other hardened material, including aluminum, TORLON (a polyamideimide) available from Solvay Advanced Polymers of Alpharetta, Ga., ULTEM available from General Electric Company of Fairfield, Conn., and TEFLON available from E.I. du Pont. A drive piston valve 124 is coupled to the rod 118 at the lower end 122, so that together the two form an assembly for elevating liquid toward the discharge opening 116.
A foot valve unit 126 is disposed within riser pipe 112 and below the drive piston valve 124 and may remain in a substantially fixed position relative to the riser pipe 112 during movement of the piston assembly. The foot valve 126 may be disposed within a liner of the riser pipe 112, for example. Alternatively to the embodiments shown, more than one drive piston valve 124 and/or more than one foot valve 126 may be incorporated in the device. Further in some examples, the foot valve 126 may be disposed outside the riser pipe 112, sealably attached to the lower end 115 of the riser piper 112.
Further still, while the drive piston valve 124 and the foot valve 126 are illustrated as ball valves, other valve structures may be used to allow liquid to flow through a valve aperture toward the discharge opening 116 and to prevent substantial back flow back into the underground reservoir.
By way of example, not limitation, the drive piston valve 124 and foot valve 126 may be formed of various materials such as the materials for the casing 110. Preferably, the materials are chemically inert with respect to the fluid being pumped, resistant to corrosion, durable over long life cycles and can form a liquid tight seal with whatever materials are chosen for seals, such as those described herein. By way of example, not limitation, example materials include polytetrafluoroethylene (PTFE) and stainless steel. Other materials include industrial ceramics, chemically resistant organic polymers, and metallic alloys, a list provided by way of example, not limitation. In an example, the outer casings for the drive piston valve 124 and foot valve 126 are formed of DELRIN or PEEK (polyetheretherketone) (available from Victrex USA of Greenville, S.C., etc.).
In the form of a DELRIN, PEEK, or other resilient material of the drive piston unit 124, it may be desired to use a sealing member compressibly extending between an inner wall of the riser pipe 112 and an outer surface of the unit 124. In the illustrated examples of
To connect the drive piston 124 to the piston rod 118, a rod coupler 226 is screw mounted to a vented opening end 228 of the drive piston 124 and to the piston rod 118 through connector bolt 230.
The sealing plate 312 has an inner wall 316 for engaging the check ball 310 and an outer wall 318 to be disposed adjacent the inner wall 313. The outer wall 318 may seal directly against the inner wall 313, in which case, it will generally be desired to size the dimensions of the wall 318 to match that of the inner wall 313 to allow both assembly prior to operation and engagement maintenance of the plate 312 at the sealing end 314 during operation.
The outer wall 318 may be sealed against the inner wall 313 through a compression element such as an o-ring 320 partially recessed within receiving slot 322 machined into the plate 312. Having a resilient compression element allows the sealing plate to be tightly engaged inside the drive piston 124, but without damaging the inner housing wall. The o-ring 320 sealing element may engage the inner surface 313 or it may extend into a groove formed therein. That groove may be formed to receive only the o-ring 320 or the entire outer edge 318, such as when the diameter of the sealing, plate 312 is larger than the inner diameter for wall 313.
Other compressible seals may be used for the sealing plate 312. The outer wall 318 as a portion of the metal plate 312 may be replaced by a compressible cap forming the entire outer wall 313. The cap may be glue mounted, screw mounted, molded, slidably engaged, or otherwise affixed to the metal portions of the seal plate 312.
Further still, while the o-ring 320 may extend around the entire circumference of the plate 312, alternatively the compressible sealing member may be formed over only a portion of that circumference and still form a tight seal.
Preferably, the inner wall 316 is spaced from the outer wall 318 to be flush with an inlet wall 319, although alternatively the inner wall 316 may be spaced a shorter or longer distance from outer wall 318.
With a metal sealing plate, it is possible that a metal sealing plate may gall against, and under constant valve actuation force from, the metallic check ball. The metal-on-metal contact has been found to be beneficial for quick actuation of the check ball, but using a sharp edge as the sealing ring is generally undesirable as the edge may damage the check ball or vice versa especially under chemical encrustation which may occur over time as certain liquid particulate is being pumped. Furthermore, it has been found that sharp corner seals may present an unstable contact from which a check ball may move laterally when in the closed, i.e., sealed, position.
To address these possibilities, the sealing plate 312 includes a truncated inner seal corner 323 for engaging with a check ball. The truncated corner 323 may be a flat-beveled edge, for example, formed from a conical cut to a right angle corner, as shown in
Returning to
Although not illustrated, it is noted that the sealing plate 312 may take on different shapes to marry against different inner housing geometries. Further still, the plate 312 may be further held in position by a lip ring protruding from the inner wall 312 a sufficient distance to provide support along a vertical access, but sufficiently small to allow plate insertion into the housing 300.
An example of the foot valve seat 126 is further shown in
The sealing plate 410 includes a truncated sealing corner 421 which may be like the truncated corner 323 described above.
An o-ring 422 is provided in mating slots for further allowing for a tightened seal in the riser pipe 112. Chamfered lead edges 424 and 426 are also provided in the illustrated example.
For retaining the check ball 408 within the cavity 402, a nylon rod may be extended across the diameter of the cavity 402 through opposing bore holes 428 (one shown). This allows a nearly continuous vent for liquid fluid around outlet end 430 of the foot valve 126.
Although certain apparatus constructed in accordance with the teachings of the invention have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all embodiments of the teachings of the invention fairly falling within the scope of the appended claims either literally or under the doctrine of equivalence.
