Hydraulic Stroke Increaser

Abstract

A stroke increaser for use in well pumping systems and the like has a fluid motor, with the cylinder of the fluid motor attached to an actuator, such as the bridle of a walking beam assembly, and the piston of the fluid motor connected to a longitudinally extending hollow polish rod. A fluid pump has a cylinder arranged in the pump assembly and has a piston connected to the other end of the hollow polish rod. A transverse bore is arranged in each end portion of the hollow polish rod. A hydraulic fluid is provided in the cylinders in the hollow polish rod. When the actuator begins an upward stroke, both pistons are in the bottom portion of their respective cylinders. The piston of the fluid pump will be forced upwardly with respect to its associated cylinder by the upward movement of the actuator. The hydraulic fluid will be forced from the cylinder of the fluid pump through the hollow polish rod and into a cylinder of the fluid motor. The piston of the fluid motor will thus be forced upwardly relative to the cylinder of the fluid motor and increase the stroke of sucker rods attached to the piston of the fluid pump. The above process is reversed for a downward stroke of the actuator.

Description

BACKGROUND OF THE INVENTION

1. FIeld of the Invention

This invention relates in general to new and useful improvements in pumping mechanisms, and more specifically to a stroke increasing attachment for walking beams, windmills, and the like.

2. Description of the Prior Art

When pumping fluids from great depths beneath the surface of the earth with equipment using reciprocating well rod, it is frequently desirable to increase the stroke of the rod. This is in particular a desirable alternative to increasing the speed of reciprocation of the well rod, which is usually not practical as it increases wear of the equipment with resulting increased maintenance costs.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a stroke increaser for walking beams, windmills, and the like which may be mounted on existing pump actuators to increase the stroke of the pump without requiring a modification of the pump actuator.

This and other objects are accomplished according to the present invention by providing a stroke increaser for walking beams, windmills, and the like which has slave means for attachment to an actuator. The slave means has a movably mounted first slave member connected to the actuator for movement therewith and a movably mounted second slave member arranged for movement relative to the first slave member. A master means is provided for moving the second slave member relative to the first slave member, and has a first master member and a second master member connected to the second slave member for movement therewith and arranged for movement with respect to the first master member.

In a preferred embodiment of the present invention, the first slave member is a slave cylinder, and the second slave member is a slave piston arranged in the cylinder to form a fluid motor. The first master member is a master cylinder, and the second master member is a master piston arranged in the master cylinder and adapted to be connected to a sucker rod. The master cylinder and master piston form a fluid pump.

A longitudinally extending hollow polish rod forming a passageway is connected to the slave piston and the master piston. This hollow polish rod has spaced end portions adjacent a respective piston. Each end portion is provided with a transverse bore in communication with the passageway for passing a hydraulic fluid between the passageway and an associated one of the cylinders. The hydraulic fluid is arranged in the slave cylinder and master cylinder, and is transferrable from one cylinder to the other through the bores and passageway of the polish rod. In this manner, a movement of the master piston with respect to the master cylinder will cause a movement of the slave piston with respect to the slave cylinder.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof, werein like numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational, schematic view showing a stroke increaser according to the present invention in combination with a walking beam assembly.

FIG. 2 is a fragmentary, partly sectional view showing a stroke increaser according to the present invention with a portion thereof arranged in a pump assembly.

FIG. 3 is a sectional view taken generally along the line 3--3 of FIG. 2.

FIG. 4 is a sectional view taken generally along the line 4--4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1 of the drawings, a well pumping system 10 has an actuator 12, sucker rod 14 (FIG. 2), and a stroke increaser 16 which is constructed according to the present invention.

Actuator 12 has a walking beam assembly 18 with a Sampson post assembly 20 provided with a pivot pin 22 to which a walking beam 24 is pivotally attached in the conventional manner. A conventional beam drive 26 is connected to one end of walking beam 24, and a conventional horse head 28 is connected to the other end thereof. Although only one plate of horse head 28 is shown in FIG. 1, it is understood that there are a pair of such plates as is conventional.

Referring now to FIGS. 2 to 4 of the drawings, a plurality of reins 30 are connected to horse head 28 in a conventional manner not shown, and a bridle 32 is connected to reins 30. A slave means 34 for attachment to actuator 12 is connected thereto indirectly by means of a movably mounted first slave member 36 pivotally connected to bridle 32. Slave means 34 also has a movably mounted second slave member 38 arranged for movement relative to first slave member 36. Stroke increaser 16 further has a master means 40 for moving second slave member 38 relative to first slave member 36. Master means 40 has a fixed first master member 42, and a second master member 44 connected to second slave member 38 for movement therewith and arranged for movement with respect to first master member 42.

First slave member 36 has a flanged end member 45 provided with a hole, and a slave cylinder 46 connected to end member 45. End member 45 is connected to bridle 32 as by a pin 47 passing through the hole provided in member 45 and a matching hole provided in bridle 32. Second slave member 38 is a slave piston 48 arranged in slave cylinder 46 to form a fluid motor 50 therewith. Piston 48 is maintained in sealing relationship with respect to cylindrical wall 51 of cylinder 46 by means of suitable, known seals 52. A conventional air filter 54 is mounted on cylinder 46 and is arranged in communication with chamber 55 of fluid motor 50 for permitting air to pass out of chamber 55 when piston 48 moves upwardly in cylinder 46.

As shown in the drawings, first master member 42 is a master cylinder 56, and second master member 44 is a master piston 58 arranged in master cylinder 56 and adapted to be connected to a sucker rod 14. Master cylinder 56 and master pin 58 form a fluid pump 60. Piston 58 is maintained in sealing engagement with cylindrical wall 61 of cylinder 56 as by conventional, known seals 62.

A longitudinally extending, hollow polish rod 64 forming a passageway 66 is connected at one end portion 68 to slave piston 48, and at the other end portion 70 to master piston 58. Each end portion 68, 70 is provided with a transverse bore 72, 74, respectively which are in communication with passageway 66 for passing a fluid 76 therethrough between passageway 66 and an associated one of cylinders 46, 56. Fluid 76 is preferably a known hydraulic fluid.

End portion 68 of hollow polish rod 64 is provided with a threaded portion (not shown) which passes through opening 78 in piston 48 and threadedly receives a nut 79. A fluid cushion valve 80 is arranged about hollow polish rod 64 and is biased against piston 48 by means of a conventional coiled spring 82. This arrangement provides a shock-cushioned attachment of piston 48 to polish rod 64. A conventional seal 84 is arranged in an annular groove 85 provided in an annular member 86 of an end cap assembly 87 which is connected to cylinder 46 in a conventional manner, as by a cap 88 attached by screw threads (not shown). An annular member 89 is arranged within cylinder 46 and abutting end cap assembly 86, and is provided with a chamfered portion 90 for receiving fluid cushion valve 80 when piston 48 is in its downward position (not shown).

A pump assembly generally designated by the reference numeral 92 has a stuffing box 94, a pumping tee 96, casing head 98, provided with screw threads 100 for threadingly engaging with screw threads 101 provided on a well casing 102, and well tubing 104 arranged within casing 102 and connected to pumping tee 96 in a conventional manner, as by screw threads.

Cylindrical wall 61 and polish rod 64 form an annular passage 106 for fluid 76. In addition, master cylinder 56 and well tubing 104 form a passage 108 (FIG. 4) for passing, for example, crude oil. A discharge pipe 110 is connected to pumping tee 96 in a conventional manner, and is in communication with passage 108 for discharging the pumped fluid therefrom. As shown in FIG. 2, pipe 110 is connected to pumping tee 96 by means of a threaded flange 112 which engages with screw threads on pipe 110.

Stuffing box 94 has an end cap assembly 114 threadedly engaged thereto. Assembly 114 retains a flanged, annular member 115 in place. An annular groove 116 is provided in wall 117 of member 115. Wall 117 defines on opening 118. Polish rod 64 passes through opening 118, and a conventional seal 119 provides a fluid-tight seal between rod 64 and wall 117.

A reservoir 120 may be provided for holding a reserve supply of fluid 76. This reservoir 120 is provided with a restricted opening 122 in the bottom thereof, and is connected to passage 108 by means of a line 124. A check valve 126 is preferably provided in line 124 to prevent fluid 76 from returning to reservoir 120 during an upward stroke of piston 56. Reservoir 120 enables small amounts of fluid 76 which are lost during the operation of stroke increaser 16 to be immediately supplied.

As can be appreciated from the above description, stroke increaser 16 may be readily attached to a suitable actuator 12 without extensive modification of the actuator 12. Once attached thereto, actuator 12 acts to reciprocate master piston 58 with respect to master cylinder 56. When master piston 58 moves upwardly from the bottom position of its stroke (not shown) it will force fluid 76 through bore 74, passageway 66, and out bore 72, into chamber 109. This movement of fluid 76 will cause slave piston 48, which is arranged to be in its bottom position (not shown) when master piston 58 is likewise, to be forced upwardly with respect to slave cylinder 46. It is this relative movement of piston 48 with respect to cylinder 46 that increases the stroke of sucker rod 14 and a downhole pump (not shown). That is, the stroke of master piston 48 is equal to the stroke of actuator 12, plus the stroke of slave piston 48.

For example, if master cylinder 56 permits a stroke with respect to slave cylinder 46 that has the ratio of 4:1, a 48 inch actuator stroke will give master piston 58 a stroke of 64 inches and slave piston 48 a stroke of 16 inches. A downhole pump will have a stroke of 64 inches, the same as master piston 58. This is an increase of 16 inches.

The increase in stroke for various relationships between the slave means 34 and master means 40 may be readily determined from the following evaluation:

S.sub.I A.sub.S = S.sub.I A.sub.M + S.sub.E A.sub.M

Therefore: S.sub.I = S.sub.E A.sub.M /A.sub.S - A.sub.M

Where:

S.sub.i = stroke increased length (inches)/or stroke made in slave cylinder 98.

S.sub.e = stroke lengh of existing pumping unit (inches).

A.sub.m = area of master piston, less area of hollow polish rod in sq. inches.

A.sub.s = area of slave piston, less area of hollow polish rod in sq. inches.

Thus, the new stroke length will be S.sub.I + S.sub.E.

As is well known, when beam 24 pivots so as to move horse head 28 downwardly, the conventional reins 30 prohibit power from being transferred from horse head 28 to stroke increaser 16. Thus, the latter, together with sucker rod 14, drops under its own weight due to the influence of gravity. Since only slave member 36 is connected directly to reins 30 by bridle 32, piston 48 is free to move downwardly at a faster rate than member 36, whose maximum downward movement is limited by the movement of reins 30 and bridle 32. The added weight of rods 14 assure that piston 48 will not only move downwardly faster than member 36, but also that it will move downwardly at the fastest rate permitted by the fluid in stroke increaser 16. In the case of a hydraulic fluid, this rate will be one that maintains a constant total volume in the portions of cylinders 46 and 56 between pistons 48 and 50. In this manner, piston 48 will move downwardly in member 36 during a downward stroke of reins 30 and bridle 32 until piston 48 reaches its bottom position (not shown).

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

What is claimed as new is as follows:

1. A stroke increaser, comprising, in combination:

a. slave means for attachment to an actuator, and including a movably mounted first slave member connected to the actuator for movement therewith and a movably mounted second slave member arranged for movement relative to said first slave member; and

b. master means for moving said second slave member relative to said first slave member, and having a fixed first master member, and a second master member arranged for movement with respect to the first master member and connected to said second slave member for movement therewith.

2. A structure as defined in claim 1, wherein said first slave member is a slave cylinder, and said second slave member is a slave piston arranged in said slave cylinder to form a fluid motor therewith.

3. A stroke increaser, comprising, in combination:

a. slave means for attachment to an actuator, and including a first slave member connected to the actuator for movement therewith and a second slave member arranged for movement relative to said first slave member, said first slave member being a slave cylinder, and said second slave member being a slave piston arranged in said slave cylinder to form a fluid motor therewith; and

b. master means for moving said second slave member relative to said first slave member, and having a fixed first master member, and a second master member connected to said second slave member for movement therewith and arranged for movement with respect to said first master member, said first master member being a master cylinder, and said second master member being a master piston arranged in said master cylinder and adapted to be connected to a sucker rod, said master cylinder and master piston forming a fluid pump.

4. A structure as defined in claim 3, further including a longitudinally extending, hollow polish rod forming a passageway and connected to said slave piston and said master piston, and including spaced end portions adjacent a respective piston, each end portion provided with a transverse bore in communication with said passageway for passing a fluid therethrough between said passageway and an associated one of said cylinders.

5. A structure as defined in claim 4, further including a fluid arranged in said slave cylinder and master cylinder and transferrable from one cylinder to the other through the bores and passageway of said polish rod.

6. A stroke increaser, comprising, in combination:

a. slave means for attachment to an actuator, and including a first slave member connected to the actuator for movement therewith and a second slave member arranged for movement relative to said first slave member; and

b. master means for moving said second slave member relative to said first slave member, and having a fixed first master member, and a second master member connected to said second slave member for movement therewith and arranged for movement with respect to said first master member, said first master member being a master cylinder, and said second master member being a master piston arranged in said master cylinder and adapted to be connected to a sucker rod, said master cylinder and master piston forming a fluid pump.

7. A structure as defined in claim 6, further including a longitudinally extending hollow polish rod forming a passageway and connected to said second slave member and said master piston, and including spaced end portions adjacent the member and piston, each end portion provided with a transverse bore in communication with said passageway for passing a fluid therethrough between said passageway and an associated one of the first slave member and said master cylinder.

8. A structure as defined in claim 7, further including a fluid arranged in said first slave member and master cylinder and transferrable from one member and cylinder to the other through the bores and passageway of said polish rod.

9. A structure as defined in claim 1, further including a longitudinally extending hollow polish rod forming a passageway and connected to said second slave member and said second master member, and including spaced end portions adjacent a respective member, each end portion provided with a transverse bore in communication with said passageway for passing a fluid therethrough between said passageway and an associated one of the first slave and master members.

10. A structure as defined in claim 9, further including a fluid arranged in said first slave member and first master member and transferrable from one member to the other through the bores and passageway of said polish rod.