US2243117A - Counterbalanced pumping unit - Google Patents

Description

May 27, 1941. E. w. PATTERSON GOUNTERBALANCED PUMPING UNIT Original Filed Nov. 19, 1955 6 Edgar "(Patterson 2;.

Patented May 27, 1941 and one-half to Charles Angeles, Calif.

M. O'laeary, In, Los

3 Claims. (01. 74-589) The present invention relates generally to well pumping .units and more particularly to fluidbalanced units, especially air-balanced units and is in general a division of my copending application filed November 19, 1935, under Serial Number 50,540, now Patent No. 2,148,638.

According to the present invention for the operation of a deep well pump, it is essential that fluid be maintained at a substantially constant pressure in a receiving tank by a compressor arranged and operated so that its compression strokes coincide with the compression strokes of the air balance, and its stroke length rendered constant after the desired maximum pressure has been reached in the receiving tank, while at the same time provision is made for variation of its compression space during and after accumulation of said maximum pressure in the tank, to regulate the maximum pressure in the receiving tank and to accommodate the compressor to any adjustment or change in stroke length of the pump.

The present invention therefore has for its primary object the provision of means in combination which will bring about the foregoing and not only bring about full cooperation of the pump, air balance and compressor, so that the air balance and compressor fully coast to control the pump in operation, but so that ready effective adJustment is permitted to properly maintain desired pressure at the various stroke lengths it may be necessary to operate the pump.

The invention is illustrated by way of example in the accompanying drawing, in which:

Figure 1 is a view in side elevation showing the application of the present invention to a pump structure.

Figure 2 is an enlarged view in vertical section and elevation showing the pump unit as seen on the line 2-2 of Figure 1, and particularly disclosing the compression space adjusting means.

Figure 3 is a view through the pump unit as seen on the line 3-3 of Figure 2 and shows the connections provided between the opposite ends of the pump cylinder whereby the pump may be compounded.

Figure 4 is a view in transverse section as seen on the line 4-4 of Figure 2 and shows the relative arrangement of the inlet and outlet connec-' unit which includes a receiving tank. II and Gil structural frame members l2 rigidly connected therewith. Mounted upon the base unit is a power unit "which includes a driving means and gear reduction means through which a shaft l4 may be driven. Secured upon the shaft I4 is a throw of the crank and an adjustment of the pump stroke as we shall presently see.

Engaging the crank pin I8 is the lower end of a connecting rod l1, the upper end of which connects to a pivot it carried by a. crosshead of the rocking beam IS. The beam I9 is shown pivoted at one end, for vertical swinging movement, upon a fulcrum shaft 20 which is supported at the upper end of a vertical Samson post 2lupstanding from the base structure and connected at the lower end thereof with the sub-frame 10 by bolts 22. The outer free end of the rocking beam [9 is shown as provided with a horse #head 23 formed with a segment 24, over which the reins 25 of a pump polish rod are led.

Rocking beam cushion and counterbalance means are provided and shown as located in an upright position between the free end of the rocking beam and the crosshead for connecting rod I! by which power is applied to the beam. This 'cushioning and counterbalancing means comprises a bracket 26 pivoted on a shaft 21 carried by the rocking beam. A cylinder 28 is secured to the bracket 26 and depends therefrom. Mounted within the cylinder 28 is a piston 29, through which opens the upper end of a tubular piston rod 30, said rod extending upwardly through the bottom of the cylinder 28. The lower end of this tubular piston rod 30 is fitted with a cross shaft 3| carried in bearings 32. The cross shaft 3| is also tubular and is connected to a flexible conduit 33 which leads from the cross shaft to the air receiving tank II. A valve 34 controls the flow of fluid to and from the container Ii through the conduit 33. Thus during the downstroke of the rocking beam l9, brought about by rotation of the crank disk IS, the weight of the pump rods in the well will be resisted by the compressed fluid between the cylinder head 28' and the piston 29, assuming proper maximum pressure is present in the tank I l. During its upstroke or load stroke, the rocking beam will be actuated by the power connections including the crank -disk, its crank pin l6, and the connecting rods l1, augmented by the pressure oi the fluid within the receiving tank II, by reason of its being in unrestricted communication with the' compression space in cylinder 2| through the pisfor the reason that such a structure can act incidental to the operation of the oscillating rocking beam to maintain the pressure of the fluid within the receiver ll constant. This is accomplished by the compressor unit generally indicated at 88 in the drawing, and shown as mounted upon the base unit. The compressor unit ll comprises a cylinder 38 which is formed with a closed head 31 at its lower end, the cylinder beingsecured to the base unit by a footing member 38. The upper end of the cylinder is fitted with a packing gland I! through which a piston rod 40 reciprocates. Attention is directed to the fact that this gland is of considerable length and acts to prevent the piston rod from being laterally displaced as it reciprocates. piston rod ll within cylinder 38 is a piston ll. Mounted at the upper end 01' the piston rod 40 is a crosshead 42 fitted with trunnions 43, which are rotatably disposed within bearings at the lower ends of a pair 01' pitman rods 44. The upper ends of these rods are secured to the rocking beam It by pivots 45. The crosshead carries an adjustable sleeve 48, which is threaded through the crosshead and has a central bore to receive the piston rod 40. A nut 41 is mounted upon the sleeve and adjustably locks the sleeve in a desired position. Lock collars 48 are pinned on the upper end of the piston rod 40 by shear pins 49, which may be sheared in the case of excess strain acting upon the piston ll. It will also be seen that by the adjustment afforded by the sleeve 46 the piston rod 40 may be shifted so that the piston U will occupy a difierent stroke position within the cylinder. This piston and the cylinder forming the compressor act in accordance with the well-known isothermal compression formula, in which:

I Under this formula the piston when adjusted will act to change the compression ratio, as for example:

By this single adjustable arrangement it is not only possible to adjust the piston 40 within the cylinder II to feed any desired pressure of fluid into the tank H during accumulation of pressure therein and subsequent maintenance of such pressure, at any stroke length of the pump, but it is also possible to compensate for any change of pump stroke brought about by shifting the crank pin l6 into any opening l6 of the crank disk [5.

As shown in Figure 2 of the drawing, it is preferable that the compressor be provided with an air inlet pipe 50, having connected thereto a check valve l through which fluid may be drawn into the portion of the cylinder 3' below the piston ll. An air outlet 52 is flttedwith a check valve 53 and supplies air through a pipe 54 to the receiving tank I I. A valve 55 is interposed in this line as well as a pressure gauge 55', said valve 55 being located between the gauge I5 and tank ll,

so that, by closing valve II, the pressure of air developed by the adjusted air pump will at once appear on the gauge II. a cylinder 86 into an upper compression space H and a lower compression space II. The lower end of the lower space is defined by the end wall 31. The upper end of the upper space is defined by an end wall oi the packing head. II. A pipe I! extends through the wail of the cylinder a' adjacent to the end wall I. As here shown, a 1' connection I is attached to the pipe and on a laterally extending leg carries a stopcock ll.

A second T 82 is connected to the first T and in turn carries a check valve 08 through which air may be drawn into the pipe II, but may not flow in the opposite direction. Connected to the laterally extending leg of the 1 O2 is a pipe 84 which is fitted at its lower end with an elbow ll attached to a check valve II. The check valve 0! permits the fiow oi fiuid into the cylinder but not in an opposite direction. A pipe connection 01 is attached to the check valve ll and extends Mounted on the lower end 01' the through the wall or-thecylinder ll at a point where it will be covered on the lower portion or the downstroke of the piston and uncovered for a portion of the upstroke of the piston. It is to be understood that the valve 5| connecting with the lower cylinder compartment I1 is a check valve which will allow inflow of the fiuid tothe cylinder but will prevent an outfiow oi fiuid. The valve 53 is a check valve, which at all times allows regulated communication between the compartment 51 of the cylinder and the receiving tank II. This is of considerable importance in the present device, due to the fact that the pressure within the compartment ll of the cylinder and the receiving tank will be the same. and for the further reason that this arrangement does not cause all of the fluid within the cylinder 38 to be dis.- charged into the' receiving tank. Thus there is no tendency to build up heat in the compressor unit, as by this arrangement it will be noted that after the pressure in receiver II has reached the pressure at which the compressor is set, the same fluid is being compressed and expanded as the piston reciprocates. The valves and the piping which establishes communication from the pipes 59 to I! make it possible to supercharge the cylinder as the piston ll makes an upstroke. This, however, may beoptionally done by control of the stopcock II.

In operation of the present invention, the required pressure for the receiving tank II is determined by the loadunder which the pumping mechanism is working and by the pressure of fluid necessary within the cylinder 28 to cushion and counterbalance this load and to also aid in lifting the rocking beam IS. The valve 34 may be closed to stop the passage of fluid through conduit 33 and the piston 30 to the cylinder 28 if desired. It will be assumed, for example, that the fluid pressure required is one hundred pounds. It will then be evident that the compressor unit 35 must be adjusted to maintain the one hundred pounds pressure in the receiving tank ll, irrespective of the stroke length at which the pump is operating. Pressure may be determined by operating the compressor and closing the valve 55, and reading the pressure indicated on the gauge 55. The performance of the compressor may be varied by adjusting the piston rod 4. with relation to the crosshead 42, so that the compression space Il within the cylinder will be such as to produce one hundred pounds pressure as indicated on The piston 4| divides the gauge 55'. This'adjustment is made by regulating the sleaze 46 within the crosshead to vary the position of compressor piston 4| in the compressor cylinder 36 and in this way vary the compression space 51. It is evident therefore that at any set stroke length of the the piston 4| maintains a constant stroke and that, in providing for adjustment in the relative position of said piston in cylinder 36, simple and effective means are present to both compensate for any adjustment which may be necessary in the length of pump stroke and to quickly bring the pressure tank up to maximum and subse quently maintain such maximum, at any length of pump stroke within the range of adjustment previously described.

Under normal conditions, it will be assumed that the piston 4| is to create a compression stroke without a supercharging action, in which event the stopcock 6| is left open. Thus as the:

piston moves upwardly to the extreme upper position, the port of the pipe 61 will be uncovered by the piston 4| and no air will flow into the compression space 51 through the check valve 66 and the pipe 64 by reason of the fact that no compression of air can take place above piston 4| while valve 6| is open. Prior to the time that the port of pipe 61 is uncovered, air will be drawn into the compression chamber 51 through the check valve and the pipe 50. On the downstroke of the piston 4|, the check valve 5| will be closed and, as the piston 4| passes the port of pipe 61, the compression chamber 51 will be closed against the inflow of air, and pressure will be imposed upon the entrapped air as it is forced outwardly through the pipe 52 and the valve 53 and then through pipe 54 to the receiving tank I l. Upon the next stroke of the piston 4|, the procedure will be repeated and, in the event it is desirable to supercharge the fluid within compression space 51, the stopcock 6| is closed. Thus on a downstroke of the piston 4|, air will be drawn into the displacement space 56 above the piston 4| through check valve 63, pipe connections 60 and 62, and the pipe 59, since on a portion of the downstroke of the piston 4| the port of pipe 61 is closed, so that air may be drawn into the displacement space 56 by suction upon the downstroke of the piston 4|. On the upstroke of piston 4|, the check valve 63 will be closed and the fluid which has been entrapped within the displacement space 56 will be compressed and forced around through the pipe 64 and the check valve 66 to the pipe 61. If the piston 4| is positioned so that in its upward movement it uncovers the port of pipe 61, the compressed fluid from the displacement space 56 will be expelled into the compression space 51 so that the compression space 51 will not only contain a normal volume of air drawn into it through the valve 5|, but will also contain the air from the displacement space 56 which is under a predetermined pressure. Under the downstroke of the piston 4|, the air under pressure within the compression space 51 will be further compressed and forced into the receiving tank through the pipe 54. Thus by the arrangement here shown, a multi-stage compression may be obtained. It will-further be evident that the arrangement also insures that while the compressor is working continuously as an incident to the pumping operation, it will act to maintain the fluid pressure within the receiving tank at a constant pressure, irrespective of any leakage which might occur in the apparatus.

It is also obvious that, since air is compressed in the compressor chamber 51 during each downstroke of. beam l9 irrespective of one or two- 1 stage compressing action, and downstroke of beam l9 alsocauses compression of air in the balance cylinder 28, the compressor cooperates with the balance cylinder in balancing the movements of the beam IS in operation. This effect is, furthermore, increased when, as before stated, pressure in the receiver H has reached the pressure'at which the compressor is set, and in the latter the same fluid is being alternately compressed and expanded in chamber 51 as the piston 4| reciprocates.

It will-thus be seen that, with the counterbalance andcushioning apparatus here shown, it is possible to regulate the apparatus to operate at any desired pressure and to maintain the pressure as adjusted and set by'simple and effective means, with minimum loss of power and in a manner to uniformly apply such power.

While I have shown the preferred form of my invention as now known to me, it will be understood that various changes might be made in the combination, construction, and arrangement of parts, by those skilled in the art, without departing from the spirit of the invention as claimed.

What is claimed is:

1. A well pumping structure comprising a base, a Samson post extending upwardly therefrom, a rocking beam pivoted at one end thereof for vertical oscillation, power means mounted on the base and engaging the rocking beam at a point intermediate its ends for oscillating the beam, cushioning and counterbalance means interposed between the base and the rocking beam, said means including a cylinder and a piston connected to the beam'to reciprocate as the beam rocks, an air receiving tank in constant open communication with the compression space of said cylinder and otherwise closed during normal operation whereby the pressure of the fluid within the tank will actuniformly at all times in counterbalance to aid in lifting the beam on the upstroke and to resist the movement of the beam on its downstroke, an air compressor including a cylinder associated with the base and having a piston therein, a connection between the said piston and the rocking beam whereby the piston will reciprocate within said cylinder during operation of the beam, said compressor also including valved means for taking air into the compressor space of said air compressor cylinder and valved means for discharging air from said space into the receiving tank as it is compressed, to establish and maintain a set maximum pressure in the tank corresponding to the maximum output pressure of the compressor, whereby the pressure in the tank thereupon holds the compressor discharge valve closed and the compressor thus alternately compresses air and permits the same air to expand in the compressor cylinder as long as its set maximum output pressure is within the tank, the compres sion period of said compressor agreeing with the compression period or the cushioning and counterbalance means and cooperating therewith to balance movement of the rocking beam, means in connection with said power means for adjusting the stroke length of the beam, and means for adjusting the compressor piston in the cylinder to regulate the maximum output pressure thereof and thus the maximum pressure in the air receiver and the cushioning and counterbalance means at any given stroke length of the beam.

2. A well pumping structure comprising a base, a Samson post extending upwardly therefrom, a rocking beam pivoted on the post for vertical oscillation, power means connected to the beam for oscillating the same, cushioning and counterbalance means interposed between the base and the rocking beam and including a cylinder and piston relatively reciprocating as the beam oscillates, an air receiving tank closed at all times to the atmosphere and in constant open communication with the compression space of said cylinder whereby pressure of air within thetank will act through the counterbalance means to aid in lifting the beam on its upstroke and to resist the beam on its downstroke, an air compressor actuated by the rocking beam and compressing air therein to a predetermined pressure, said compressor discharging into said tank, and maintaining by its predetermined pressure output a set maximum pressure in the latter, and said compressor including a piston, piston chamber and air intake and outlet valves for said chamber, together constituting compressing means alternately compressing and expanding air therein when a set maximum pressure has been reached in the tank and the air outlet valve of the compressor cylinder is held closed by the tank pressure, and means for adjusting the piston in said piston chamber whereby a predetermined maxi mum compressor output pressure may be retained under difierent stroke lengths of the rocking beam, and whereby to regulate the maximum output pressure thereof and the maximum pressure in the receiving tank.

3. In a well pumping unit, a support, a Samson post, a beam pivoted on said post to swing vertibalancing the eirective movements 01' the beam,

a compressor includingga cylinder having valved air intake and discharge connections, and a piston therein connected to, and actuated by, the beam, an air reservoir into which the compressor discharge connection extends and the maximum working pressure of which corresponds to the maximum output pressure of the compressor and is controlled thereby, said reservoir having an open connection with the air balance and being otherwise closed during normal operation whereby maximum pressure therein will close the discharge valve of the compressor and cause alternate expansion and compression of air in the compressor, and means in the connection between the compressor piston and the beam for adjusting the compressor piston within its cylinder to compensate for changes in stroke length of the beam and also vary the effective operation of the compressor to increase or decrease pressure of the discharge from the compressor at any stroke length of the beam.

EDGAR W. PATTERSON.

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